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Sample records for annual plant populations

  1. Causes and consequences of complex population dynamics in an annual plant, Cardamine pensylvanica

    SciTech Connect

    Crone, E.E.

    1995-11-08

    The relative importance of density-dependent and density-independent factors in determining the population dynamics of plants has been widely debated with little resolution. In this thesis, the author explores the effects of density-dependent population regulation on population dynamics in Cardamine pensylvanica, an annual plant. In the first chapter, she shows that experimental populations of C. pensylvanica cycled from high to low density in controlled constant-environment conditions. These cycles could not be explained by external environmental changes or simple models of direct density dependence (N{sub t+1} = f[N{sub t}]), but they could be explained by delayed density dependence (N{sub t+1} = f[N{sub t}, N{sub t+1}]). In the second chapter, she shows that the difference in the stability properties of population growth models with and without delayed density dependence is due to the presence of Hopf as well as slip bifurcations from stable to chaotic population dynamics. She also measures delayed density dependence due to effects of parental density on offspring quality in C. pensylvanica and shows that this is large enough to be the cause of the population dynamics observed in C. pensylvanica. In the third chapter, the author extends her analyses of density-dependent population growth models to include interactions between competing species. In the final chapter, she compares the effects of fixed spatial environmental variation and variation in population size on the evolutionary response of C. pensylvanica populations.

  2. Understanding past, contemporary, and future dynamics of plants, populations, and communities using Sonoran Desert winter annuals.

    PubMed

    Huxman, Travis E; Kimball, Sarah; Angert, Amy L; Gremer, Jennifer R; Barron-Gafford, Greg A; Venable, D Lawrence

    2013-07-01

    Global change requires plant ecologists to predict future states of biological diversity to aid the management of natural communities, thus introducing a number of significant challenges. One major challenge is considering how the many interacting features of biological systems, including ecophysiological processes, plant life histories, and species interactions, relate to performance in the face of a changing environment. We have employed a functional trait approach to understand the individual, population, and community dynamics of a model system of Sonoran Desert winter annual plants. We have used a comprehensive approach that connects physiological ecology and comparative biology to population and community dynamics, while emphasizing both ecological and evolutionary processes. This approach has led to a fairly robust understanding of past and contemporary dynamics in response to changes in climate. In this community, there is striking variation in physiological and demographic responses to both precipitation and temperature that is described by a trade-off between water-use efficiency (WUE) and relative growth rate (RGR). This community-wide trade-off predicts both the demographic and life history variation that contribute to species coexistence. Our framework has provided a mechanistic explanation to the recent warming, drying, and climate variability that has driven a surprising shift in these communities: cold-adapted species with more buffered population dynamics have increased in relative abundance. These types of comprehensive approaches that acknowledge the hierarchical nature of biology may be especially useful in aiding prediction. The emerging, novel and nonstationary climate constrains our use of simplistic statistical representations of past plant behavior in predicting the future, without understanding the mechanistic basis of change.

  3. Population cycles produced by delayed density dependence in an annual plant.

    PubMed

    Gonzalez-Andujar, J L; Fernandez-Quintanilla, C; Navarrete, L

    2006-09-01

    In contrast to insect and animal populations, little attention has been directed to the study of cycles in plant populations. It has been argued on theoretical grounds that plants present stable dynamics. Nevertheless, there are examples where plant populations appear to exhibit oscillatory dynamics, but the oscillatory signal is variable and comes from very short time series data. Using a combination of time series, models, and empirical results, we present evidence of population cycles for Descurania sophia in a 16-year field experiment. Endogenous and exogenous causal mechanisms were studied to identify processes underlying this temporal dynamic. Our results show a 4-year cycle produced by delayed density dependence. We suggest that high nutrient levels might be responsible for the observed dynamics of D. sophia. Our results suggest that although plant population dynamics may be stabilized by direct density dependence, delayed density dependence could destabilize dynamics.

  4. Effects of simulated daily precipitation patterns on annual plant populations depend on life stage and climatic region

    PubMed Central

    Köchy, Martin

    2008-01-01

    Background To improve the understanding of consequences of climate change for annual plant communities, I used a detailed, grid-based model that simulates the effect of daily rainfall variability on individual plants in five climatic regions on a gradient from 100 to 800 mm mean annual precipitation (MAP). The model explicitly considers moisture storage in the soil. I manipulated daily rainfall variability by changing the daily mean rain (DMR, rain volume on rainy days averaged across years for each day of the year) by ± 20%. At the same time I adjusted intervals appropriately between rainy days for keeping the mean annual volume constant. In factorial combination with changing DMR I also changed MAP by ± 20%. Results Increasing MAP generally increased water availability, establishment, and peak shoot biomass. Increasing DMR increased the time that water was continuously available to plants in the upper 15 to 30 cm of the soil (longest wet period, LWP). The effect of DMR diminished with increasing humidity of the climate. An interaction between water availability and density-dependent germination increased the establishment of seedlings in the arid region, but in the more humid regions the establishment of seedlings decreased with increasing DMR. As plants matured, competition among individuals and their productivity increased, but the size of these effects decreased with the humidity of the regions. Therefore, peak shoot biomass generally increased with increasing DMR but the effect size diminished from the semiarid to the mesic Mediterranean region. Increasing DMR reduced via LWP the annual variability of biomass in the semiarid and dry Mediterranean regions. Conclusion More rainstorms (greater DMR) increased the recharge of soil water reservoirs in more arid sites with consequences for germination, establishment, productivity, and population persistence. The order of magnitudes of DMR and MAP overlapped partially so that their combined effect is important for

  5. Quantifying how fine-grained environmental heterogeneity and genetic variation affect demography in an annual plant population.

    PubMed

    Latimer, Andrew M; Jacobs, Brooke S

    2012-11-01

    The ability of plant species to colonize new habitats and persist in changing environments depends on their ability to respond plastically to environmental variation and on the presence of genetic variation, thus allowing adaptation to new conditions. For invasive species in particular, the relationship between phenotypic trait expression, demography, and the quantitative genetic variation that is available to respond to selection are likely to be important determinants of the successful establishment and persistence of populations. However, the magnitude and sources of individual demographic variation in exotic plant populations remain poorly understood. How important is plasticity versus adaptability in populations of invasive species? Among environmental factors, is temperature, soil nutrients, or competition most influential, and at what scales and life stages do they affect the plants? To investigate these questions we planted seeds of the exotic annual plant Erodium brachycarpum into typical pasture habitat in a spatially nested design. Seeds were drawn from 30 inbred lines to enable quantification of genetic effects. Despite a positive population growth rate, a few plants (0.1 %) produced >50 % of the seeds, suggesting a low effective population size. Emergence and early growth varied by genotype, but as in previous studies on native plants, environmental effects greatly exceeded genetic effects, and survival was unrelated to genotype. Environmental influences shifted from microscale soil compaction and litter depth at emergence through to larger-scale soil nutrient gradients during growth and to competition during later survival and seed production. Temperature had no effect. Most demographic rates were positively correlated, but emergence was negatively correlated with other rates.

  6. Population dynamics of Agriophyllum squarrosum, a pioneer annual plant endemic to mobile sand dunes, in response to global climate change

    PubMed Central

    Qian, Chaoju; Yin, Hengxia; Shi, Yong; Zhao, Jiecai; Yin, Chengliang; Luo, Wanyin; Dong, Zhibao; Chen, Guoxiong; Yan, Xia; Wang, Xiao-Ru; Ma, Xiao-Fei

    2016-01-01

    Climate change plays an important role in the transition of ecosystems. Stratigraphic investigations have suggested that the Asian interior experienced frequent transitions between grassland and desert ecosystems as a consequence of global climate change. Using maternally and bi-parentally inherited markers, we investigated the population dynamics of Agriophyllum squarrosum (Chenopodiaceae), an annual pioneer plant endemic to mobile sand dunes. Phylogeographic analysis revealed that A. squarrosum could originate from Gurbantunggut desert since ~1.6 Ma, and subsequently underwent three waves of colonisation into other deserts and sandy lands corresponding to several glaciations. The rapid population expansion and distribution range shifts of A. squarrosum from monsoonal climate zones suggested that the development of the monsoonal climate significantly enhanced the population growth and gene flow of A. squarrosum. These data also suggested that desertification of the fragile grassland ecosystems in the Qinghai-Tibetan Plateau was more ancient than previously suggested and will be aggravated under global warming in the future. This study provides new molecular phylogeographic insights into how pioneer annual plant species in desert ecosystems respond to global climate change, and facilitates evaluation of the ecological potential and genetic resources of future crops for non-arable dry lands to mitigate climate change. PMID:27210568

  7. Population dynamics of Agriophyllum squarrosum, a pioneer annual plant endemic to mobile sand dunes, in response to global climate change.

    PubMed

    Qian, Chaoju; Yin, Hengxia; Shi, Yong; Zhao, Jiecai; Yin, Chengliang; Luo, Wanyin; Dong, Zhibao; Chen, Guoxiong; Yan, Xia; Wang, Xiao-Ru; Ma, Xiao-Fei

    2016-05-23

    Climate change plays an important role in the transition of ecosystems. Stratigraphic investigations have suggested that the Asian interior experienced frequent transitions between grassland and desert ecosystems as a consequence of global climate change. Using maternally and bi-parentally inherited markers, we investigated the population dynamics of Agriophyllum squarrosum (Chenopodiaceae), an annual pioneer plant endemic to mobile sand dunes. Phylogeographic analysis revealed that A. squarrosum could originate from Gurbantunggut desert since ~1.6 Ma, and subsequently underwent three waves of colonisation into other deserts and sandy lands corresponding to several glaciations. The rapid population expansion and distribution range shifts of A. squarrosum from monsoonal climate zones suggested that the development of the monsoonal climate significantly enhanced the population growth and gene flow of A. squarrosum. These data also suggested that desertification of the fragile grassland ecosystems in the Qinghai-Tibetan Plateau was more ancient than previously suggested and will be aggravated under global warming in the future. This study provides new molecular phylogeographic insights into how pioneer annual plant species in desert ecosystems respond to global climate change, and facilitates evaluation of the ecological potential and genetic resources of future crops for non-arable dry lands to mitigate climate change.

  8. Rainfall effects on rare annual plants

    USGS Publications Warehouse

    Levine, J.M.; McEachern, A.K.; Cowan, C.

    2008-01-01

    Variation in climate is predicted to increase over much of the planet this century. Forecasting species persistence with climate change thus requires understanding of how populations respond to climate variability, and the mechanisms underlying this response. Variable rainfall is well known to drive fluctuations in annual plant populations, yet the degree to which population response is driven by between-year variation in germination cueing, water limitation or competitive suppression is poorly understood.We used demographic monitoring and population models to examine how three seed banking, rare annual plants of the California Channel Islands respond to natural variation in precipitation and their competitive environments. Island plants are particularly threatened by climate change because their current ranges are unlikely to overlap regions that are climatically favourable in the future.Species showed 9 to 100-fold between-year variation in plant density over the 5–12 years of censusing, including a severe drought and a wet El Niño year. During the drought, population sizes were low for all species. However, even in non-drought years, population sizes and per capita growth rates showed considerable temporal variation, variation that was uncorrelated with total rainfall. These population fluctuations were instead correlated with the temperature after the first major storm event of the season, a germination cue for annual plants.Temporal variation in the density of the focal species was uncorrelated with the total vegetative cover in the surrounding community, suggesting that variation in competitive environments does not strongly determine population fluctuations. At the same time, the uncorrelated responses of the focal species and their competitors to environmental variation may favour persistence via the storage effect.Population growth rate analyses suggested differential endangerment of the focal annuals. Elasticity analyses and life table response

  9. Kin recognition in an annual plant.

    PubMed

    Dudley, Susan A; File, Amanda L

    2007-08-22

    Kin recognition is important in animal social systems. However, though plants often compete with kin, there has been as yet no direct evidence that plants recognize kin in competitive interactions. Here we show in the annual plant Cakile edentula, allocation to roots increased when groups of strangers shared a common pot, but not when groups of siblings shared a pot. Our results demonstrate that plants can discriminate kin in competitive interactions and indicate that the root interactions may provide the cue for kin recognition. Because greater root allocation is argued to increase below-ground competitive ability, the results are consistent with kin selection.

  10. Analysis of population genetic structure and gene flow in an annual plant before and after a rapid evolutionary response to drought

    PubMed Central

    Welt, Rachel S.; Litt, Amy; Franks, Steven J.

    2015-01-01

    The impact of environmental change on population structure is not well understood. This study aimed to examine the effect of a climate change event on gene flow over space and time in two populations of Brassica rapa that evolved more synchronous flowering times over 5 years of drought in southern California. Using plants grown from seeds collected before and after the drought, we estimated genetic parameters within and between populations and across generations. We expected that with greater temporal opportunity to cross-pollinate, due to reduced phenological isolation, these populations would exhibit an increase in gene flow following the drought. We found low but significant FST, but no change in FST or Nm across the drought, in contrast to predictions. Bayesian analysis of these data indicates minor differentiation between the two populations but no noticeable change in structure before and after the shift in flowering times. However, we found high and significant levels of FIS, indicating that inbreeding likely occurred in these populations despite self-incompatibility in B. rapa. In this system, we did not find an impact of climate change on gene flow or population structuring. The contribution of gene flow to adaptive evolution may vary by system, however, and is thus an important parameter to consider in further studies of natural responses to environmental change. PMID:25818074

  11. Matrix population models from 20 studies of perennial plant populations

    USGS Publications Warehouse

    Ellis, Martha M.; Williams, Jennifer L.; Lesica, Peter; Bell, Timothy J.; Bierzychudek, Paulette; Bowles, Marlin; Crone, Elizabeth E.; Doak, Daniel F.; Ehrlen, Johan; Ellis-Adam, Albertine; McEachern, Kathryn; Ganesan, Rengaian; Latham, Penelope; Luijten, Sheila; Kaye, Thomas N.; Knight, Tiffany M.; Menges, Eric S.; Morris, William F.; den Nijs, Hans; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F.; Shelly, J. Stephen; Stanley, Amanda; Thorpe, Andrea; Tamara, Ticktin; Valverde, Teresa; Weekley, Carl W.

    2012-01-01

    Demographic transition matrices are one of the most commonly applied population models for both basic and applied ecological research. The relatively simple framework of these models and simple, easily interpretable summary statistics they produce have prompted the wide use of these models across an exceptionally broad range of taxa. Here, we provide annual transition matrices and observed stage structures/population sizes for 20 perennial plant species which have been the focal species for long-term demographic monitoring. These data were assembled as part of the "Testing Matrix Models" working group through the National Center for Ecological Analysis and Synthesis (NCEAS). In sum, these data represent 82 populations with >460 total population-years of data. It is our hope that making these data available will help promote and improve our ability to monitor and understand plant population dynamics.

  12. Matrix population models from 20 studies of perennial plant populations

    USGS Publications Warehouse

    Ellis, Martha M.; Williams, Jennifer L.; Lesica, Peter; Bell, Timothy J.; Bierzychudek, Paulette; Bowles, Marlin; Crone, Elizabeth E.; Doak, Daniel F.; Ehrlen, Johan; Ellis-Adam, Albertine; McEachern, Kathryn; Ganesan, Rengaian; Latham, Penelope; Luijten, Sheila; Kaye, Thomas N.; Knight, Tiffany M.; Menges, Eric S.; Morris, William F.; den Nijs, Hans; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F.; Shelly, J. Stephen; Stanley, Amanda; Thorpe, Andrea; Tamara, Ticktin; Valverde, Teresa; Weekley, Carl W.

    2012-01-01

    Demographic transition matrices are one of the most commonly applied population models for both basic and applied ecological research. The relatively simple framework of these models and simple, easily interpretable summary statistics they produce have prompted the wide use of these models across an exceptionally broad range of taxa. Here, we provide annual transition matrices and observed stage structures/population sizes for 20 perennial plant species which have been the focal species for long-term demographic monitoring. These data were assembled as part of the 'Testing Matrix Models' working group through the National Center for Ecological Analysis and Synthesis (NCEAS). In sum, these data represent 82 populations with >460 total population-years of data. It is our hope that making these data available will help promote and improve our ability to monitor and understand plant population dynamics.

  13. Benefits to rare plants and highway safety from annual population reductions of a "native invader," white-tailed deer, in a Chicago-area woodland.

    PubMed

    Engeman, Richard M; Guerrant, Travis; Dunn, Glen; Beckerman, Scott F; Anchor, Chris

    2014-01-01

    Overabundant white-tailed deer are one of the most serious threats to woodland plant communities in the Chicago area. Moreover, the abundant deer in a highly populated area causes economic harm and poses hazards to human safety through collisions with vehicles. The artificial conditions causing the overabundance and resulting consequences qualify the white-tailed deer in the Chicago area to be considered as "native invaders". We examined the benefits of culling deer at a Chicago-area woodland preserve by comparing browse rates on four endangered plant species from years before culling began with years with culling. We also examined deer-vehicle collision and traffic flow rates on area roads from years before culling began and years with culling to assess whether population reductions may have benefited road safety in the area. All four endangered plant species (three orchid species and sweet fern) had lower browse rates in years with culls, although the decreased browsing rates were statistically distinguishable for only two of the species (grass pink orchid and sweet fern). After first verifying that traffic flow rates did not decrease from pre-cull years to years with culls, we analyzed the Illinois Department of Transportation data from area roads based on deer-vehicle collisions causing >US$500 in damage and showed a one-third reduction in deer-vehicle collisions. An economic analysis showed a cost savings during the cull years of US$0.6 million for reducing browsing to just these four monitored plant species and the reduction in deer-vehicle collisions.

  14. The Plant Population Explosion

    ERIC Educational Resources Information Center

    Swaminathan, M. S.

    1973-01-01

    Results achieved by researchers in the field of genetic plant engineering are described. However, it is believed that if their efforts were more decentralized, more farmers, especially in developing countries, could benefit and substantial advances made in production. (BL)

  15. The Plant Population Explosion

    ERIC Educational Resources Information Center

    Swaminathan, M. S.

    1973-01-01

    Results achieved by researchers in the field of genetic plant engineering are described. However, it is believed that if their efforts were more decentralized, more farmers, especially in developing countries, could benefit and substantial advances made in production. (BL)

  16. Annual production of a cottontail population

    USGS Publications Warehouse

    Conaway, C.N.; Wight, H.M.; Sadler, K.C.

    1963-01-01

    Adult females in a cottontail (Sylvilagus floridanus) population produced seven or eight litters during the 1961 breeding season. A synchrony of the conception dates was maintained throughout the breeding season. Data about ovulation rate, prenatal mortality, and litter size for each litter are presented. The first litter was smallest, averaging about three young, and the remaining litters ranged between five and six young. The last four litters may be slightly smaller than the second and third litters of the season. The total annual production of young by an adult female would be approximately 35.

  17. Consequences of limited seed dispersal within simulated annual populations.

    PubMed

    Bullock, Stephen H

    1976-09-01

    Theoretical analyses of the consequences of dispersal have been almost entirely limited to studies of colonization. A simulation model is constructed and analyzed to study the effects of dispersal within local plant populations. Rules for the growth and reproduction of individuals are deterministic and related only to competition with other plants. Rules for the dispersal of individual seeds are stochastic; the generalized seed shadow is negatively exponential. The analysis has several interesting results. 1) In small, dense populations of annuals, mortality and growth behavior are significantly affected by small-scale changes in dispersal. 2) Stable population size, at any life stage, is not environmentally fixed (e.g. by the number of safe sites) but is also a function of reproductive capacity and dispersal. 3) There is a minimum productive capability which must be exceeded for a population to be able to respond to increased dispersal. The responsive range of the parameters may be related to the grain of safe site distribution. 4) When the total number of seeds per generation is large, high dispersal decreases the number of germlings that are able to establish. 5) For plants that reach the growing stage, however, expected reproduction can exceed that of genotypes with greater reproductive capacity but less dispersal. 6) An uneven distribution of seeds is essential to a spatial patterning of mortality which can deter competitive extinction.

  18. Model of annual plants dynamics with facilitation and competition.

    PubMed

    Droz, Michel; Pękalski, Andrzej

    2013-10-21

    An individual-based model describing the dynamics of one type of annual plants is presented. We use Monte Carlo simulations where each plant has its own history and the interactions among plants are between nearest neighbours. The character of the interaction (positive or negative) depends on local conditions. The plants compete for two external resources-water and light. The amount of water and/or light a plant receives depends on the external factor but also on local arrangement. Survival, growth and seed production of plants are determined by how well their demands for the resources are met. The survival and seeds production tests have a probabilistic character, which makes the dynamics more realistic than by using a deterministic approach. There is a non-linear coupling between the external supplies. Water evaporates from the soil at a rate depending on constant evaporation rate, local conditions and the amount of light. We examine the dynamics of the plant population along two environmental gradients, allowing also for surplus of water and/or light. We show that the largest number of plants is when the demands for both resources are equal to the supplies. We estimate also the role of evaporation and we find that it depends on the situation. It could be negative, but sometimes it has a positive character. We show that the link between the type of interaction (positive or negative) and external conditions has a complex character. In general in favourable environment plants have a stronger tendency for competitive interactions, leading to mostly isolated plants. When the conditions are getting more difficult, cooperation becomes the dominant type of interactions and the plants grow in clusters. The type of plants-sun-loving or shade tolerating, plays also an important role.

  19. [Population genetics of plant pathogens].

    PubMed

    Zhu, Wen; Zhan, Jia-Sui

    2012-02-01

    Comparing to natural ecosystems, the evolution of plant pathogens in agricultural ecosystems is generally faster due to high-density monocultures, large-scale application of agrochemicals, and international trade in agricultural products. Knowledge of the population genetics and evolutionary biology of plant pathogens is necessary to understand disease epidemiology, effectively breed and use resistant cultivars, and control plant diseases. In this article, we outlined the aims of population genetic studies in plant pathogens, discuss contributions of five evolutionary forces (i.e., mutation, gene flow, recombination, random genetic drift, and natural selection) to origin, maintenance, and distribution of genetic variation in time and space, and gave an overview of current research status in this field.

  20. Competition between alien annual grasses and native annual plants in the Mojave Desert

    USGS Publications Warehouse

    Brooks, Matthew L.

    2000-01-01

    Alien annual grasses in the genera Bromus and Schismus are widespread and abundant in the Mojave Desert, and negative correlations between these aliens and native annual plants suggest that competition may occur between them. Effects of competition were evaluated by thinning alien annual grass seedlings and measuring the responses of native annual plants at three sites in the central, southcentral and southwestern Mojave Desert during 2 y of contrasting plant productivity. Effects ofBromus and Schismus were evaluated separately in the microhabitat where each was most abundant, beneath the north side of creosote bushes (Larrea tridentata) for Bromus and in the open interspace between shrubs for Schismus. Thinning of Bromus and Schismus significantly increased density and biomass of native annuals at all three sites, only during a year of high annual plant productivity and species richness. Effects of thinning were greatest for Amsinckia tesselata and for a group of relatively uncommon native annuals. Thinning also significantly increased the density and biomass of the alien forb, Erodium cicutarium. These results show that alien annual grasses can compete with native annual plants and an alien forb in the Mojave Desert and that effects can vary among years.

  1. Ornamental Annual Plants and Their Uses. Slide Script.

    ERIC Educational Resources Information Center

    Still, Steven

    This slide script, part of a series of slide scripts designed for use in vocational agriculture classes, deals with ornamental annual plants and their uses. Included in the script are narrations for use with a total of 254 slides illustrating 97 different plants. At least two slides are provided for each plant: one shows the growth habits of the…

  2. Population and community ecology of the rare plant amsinckia grandiflora

    SciTech Connect

    Carlsen, T.M.

    1996-11-01

    Research was conducted between the fall of 1992 and the spring on the population and community ecology of the rare annual plant, Amsinckia glandiflora (Gray) Kleeb. ex Greene (Boraginaceae). The research goal was to investigate the causes of the species rarity, data useful to restorative efforts. The work focused on the examination of competitive suppression by exotic annual grasses; comparisons with common, weedy congener; and the role of litter cover and seed germination and seedling establishment. Annual exotic grasses reduced A. grandiflora reproductive output to a greater extent than did the native perennial bunch grass.

  3. Impact of planting date on annual clover survival in oat

    USDA-ARS?s Scientific Manuscript database

    Interseeding annual clovers in cereal grains may help organic producers reduce the need for tillage in their cropping systems. In this study in eastern South Dakota, we evaluated seedling emergence and survival of two annual clovers in oat as affected by planting date. Berseem clover (Trifolium al...

  4. Pinellas Plant annual site environmental report for calendar year 1993

    SciTech Connect

    Not Available

    1994-06-10

    Martin Marietta Specialty Components, Inc., and the US Department of Energy are committed to successfully administering a high quality Environmental Management Program at the Pinellas Plant in Pinellas County, Florida. Part of this commitment includes accurately documenting and communicating to the Pinellas Plant stakeholder the results of their environmental compliance and monitoring activities. The Annual Site Environmental Report presents a comprehensive summary of the results of the environmental monitoring, waste management, and environmental restoration programs at the Pinellas Plant for 1993. This report also includes the plant`s performance in the areas of compliance with applicable regulatory requirements and standards and identifies major environmental management program initiatives and accomplishments for 1993.

  5. Between-Population Outbreeding Affects Plant Defence

    PubMed Central

    Leimu, Roosa; Fischer, Markus

    2010-01-01

    Between-population crosses may replenish genetic variation of populations, but may also result in outbreeding depression. Apart from direct effects on plant fitness, these outbreeding effects can also alter plant-herbivore interactions by influencing plant tolerance and resistance to herbivory. We investigated effects of experimental within- and between-population outbreeding on herbivore resistance, tolerance and plant fitness using plants from 13 to 19 Lychnis flos-cuculi populations. We found no evidence for outbreeding depression in resistance reflected by the amount of leaf area consumed. However, herbivore performance was greater when fed on plants from between-population compared to within-population crosses. This can reflect outbreeding depression in resistance and/or outbreeding effects on plant quality for the herbivores. The effects of type of cross on the relationship between herbivore damage and plant fitness varied among populations. This demonstrates how between-population outbreeding effects on tolerance range from outbreeding depression to outbreeding benefits among plant populations. Finally, herbivore damage strengthened the observed outbreeding effects on plant fitness in several populations. These results raise novel considerations on the impact of outbreeding on the joint evolution of resistance and tolerance, and on the evolution of multiple defence strategies. PMID:20838662

  6. Phenotypic selection favors missing trait combinations in coexisting annual plants.

    PubMed

    Kimball, Sarah; Gremer, Jennifer R; Huxman, Travis E; Lawrence Venable, D; Angert, Amy L

    2013-08-01

    Trade-offs among traits are important for maintaining biodiversity, but the role of natural selection in their construction is not often known. It is possible that trade-offs reflect fundamental constraints, negative correlational selection, or directional selection operating on costly, redundant traits. In a Sonoran Desert community of winter annual plants, we have identified a trade-off between relative growth rate and water-use efficiency among species, such that species with high relative growth rate have low water-use efficiency and vice versa. We measured selection on water-use efficiency, relative growth rate, and underlying traits within populations of four species at two study sites with different average climates. Phenotypic trait correlations within species did not match the among-species trade-off. In fact, for two species with high water-use efficiency, individuals with high relative growth rate also had high water-use efficiency. All populations experienced positive directional selection for water-use efficiency and relative growth rate. Selection tended to be stronger on water-use efficiency at the warmer and drier site, and selection on relative growth rate tended to be stronger at the cooler and wetter site. Our results indicate that directional natural selection favors a phenotype not observed among species in the community, suggesting that the among-species trade-off could be due to pervasive genetic constraints, perhaps acting in concert with processes of community assembly.

  7. Pinellas Plant annual site environmental report for calendar year 1995

    SciTech Connect

    1996-05-01

    Lockheed Martin Specialty Components, Inc., and the US Department of Energy are committed to successfully administering a high-quality Environmental, Safety and Health Program at the Pinellas Plant in Pinellas County, Florida. Part of this commitment includes accurately documenting and communicating to the Pinellas Plant stakeholders the results of the Pinellas Plant`s environmental compliance and monitoring activities. The Annual Site Environmental Report presents a comprehensive summary of the results of the Environmental Monitoring, Waste Management, and Environmental Restoration Programs at the Pinellas Plant for 1995. This report also includes the plant`s performance in the areas of compliance with applicable regulatory requirements and standards and identifies major Environmental, Safety and Health Program initiatives and accomplishments for 1995. As a result of the end of the Department of Energy`s Defense Programs mission (weapons production) on September 30, 1994, considerable changes at the Pinellas Plant are occurring. The Department of Energy`s Environmental Management is now the landlord of the Pinellas Plant to facilitate the plant`s new mission of transition to alternate use in support of economic development and safe shutdown. The Department of Energy sold the Pinellas Plant to the Pinellas County Industry Council in March 1995, and it is leasing back a portion of the plant through September 1997, to complete the safe shutdown and transition activities.

  8. Human population, grasshopper and plant species richness in European countries

    NASA Astrophysics Data System (ADS)

    Steck, Claude E.; Pautasso, Marco

    2008-11-01

    Surprisingly, several studies over large scales have reported a positive spatial correlation of people and biodiversity. This pattern has important implications for conservation and has been documented for well studied taxa such as plants, amphibians, reptiles, birds and mammals. However, it is unknown whether the pattern applies also to invertebrates other than butterflies and more work is needed to establish whether the species-people relationship is explained by both variables correlating with other environmental factors. We studied whether grasshopper species richness (Orthoptera, suborder Caelifera) is related to human population size in European countries. As expected, the number of Caelifera species increases significantly with increasing human population size. But this is not the case when controlling for country area, latitude and number of plant species. Variations in Caelifera species richness are primarily associated with variations in plant species richness. Caelifera species richness also increases with decreasing mean annual precipitation, Gross Domestic Product per capita (used as an indicator for economic development) and net fertility rate of the human population. Our analysis confirms the hypothesis that the broad-scale human population-biodiversity correlations can be explained by concurrent variations in factors other than human population size such as plant species richness, environmental productivity, or habitat heterogeneity. Nonetheless, more populated countries in Europe still have more Caelifera species than less populated countries and this poses a particular challenge for conservation.

  9. Living in the city: urban environments shape the evolution of a native annual plant.

    PubMed

    Yakub, Mohamed; Tiffin, Peter

    2016-10-08

    Urban environments are warmer, have higher levels of atmospheric CO2 and have altered patterns of disturbance and precipitation than nearby rural areas. These differences can be important for plant growth and are likely to create distinct selective environments. We planted a common garden experiment with seeds collected from natural populations of the native annual plant Lepidium virginicum, growing in five urban and nearby rural areas in the northern United States to determine whether and how urban populations differ from those from surrounding rural areas. When grown in a common environment, plants grown from seeds collected from urban areas bolted sooner, grew larger, had fewer leaves, had an extended time between bolting and flowering, and produced more seeds than plants grown from seeds collected from rural areas. Interestingly, the rural populations exhibited larger phenotypic differences from one another than urban populations. Surprisingly, genomic data revealed that the majority of individuals in each of the urban populations were more closely related to individuals from other urban populations than they were to geographically proximate rural areas - the one exception being urban and rural populations from New York which were nearly identical. Taken together, our results suggest that selection in urban environments favors different traits than selection in rural environments and that these differences can drive adaptation and shape population structure.

  10. Portsmouth Gaseous Diffusion Plant annual site environmental report for 1993

    SciTech Connect

    Horak, C.M.

    1994-11-01

    This calendar year (CY) 1993 annual report on environmental monitoring of the US Department of Energy`s (DOE`s) Portsmouth Gaseous Diffusion Plant (Portsmouth) and its environs consists of three separate documents: a summary pamphlet for the general public; a more detail discussion and of compliance status, data, and environmental impacts (this document); and a volume of detailed data that is available on request. The objectives of this report are to report compliance status during 1993; provide information about the plant site and plant operations; report 1993 monitoring data for the installation and its environs that may have been affected by operations on the plant site; document information on input and assumptions used in calculations; provide trend analyses (where appropriate) to indicate increases and decreases in environmental impact, and provide general information on quality assurance for the environmental monitoring program.

  11. Population Processes and Plant Virus Evolution

    USDA-ARS?s Scientific Manuscript database

    The number of studies detailing levels of sequence diversity within plant virus populations are growing at a rapid pace. At the same time, recent work has provided empirical estimates of parameters important in the life cycle of plant viruses, which in turn can help in understanding observed pattern...

  12. Pachyderms, primates, plants and population.

    PubMed

    Campbell, M M

    2001-01-01

    In the past, growth in human population has often been associated with species loss. Current rates of population growth, both globally (1 million more births than deaths every 103 hours) and regionally, pose a threat of additional ecological damage. There is a well-documented unmet demand for family planning in nearly all high-fertility countries. Improved family planning and safe abortion services will improve the health of women and their families, accelerate fertility decline, and help preserve the environment. Many ecologically vulnerable areas are especially poorly served by family planning services. Examples are given here of improving family planning services through private health providers near the Kakamega Forest in western Kenya, and of adding family planning choices to a reforestation project run by the Jane Goodall Institute near the Gombe National Park, Tanzania. Wildlife biologists can play a critical role in identifying local professionals and institutions with the potential to improve family planning.

  13. Inter-annual maintenance of the fine-scale genetic structure in a biennial plant

    PubMed Central

    Valverde, Javier; Gómez, José María; García, Cristina; Sharbel, Timothy F.; Jiménez, María Noelia; Perfectti, Francisco

    2016-01-01

    Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant. PMID:27883087

  14. Inter-annual maintenance of the fine-scale genetic structure in a biennial plant.

    PubMed

    Valverde, Javier; Gómez, José María; García, Cristina; Sharbel, Timothy F; Jiménez, María Noelia; Perfectti, Francisco

    2016-11-24

    Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant.

  15. Role of asymmetry in competition for light in a model of annual plants

    NASA Astrophysics Data System (ADS)

    Droz, Michel; Pȩkalski, Andrzej

    2012-02-01

    We propose and discuss a model describing dynamics of annual plants competing with their nearest neighbours for sunlight. The effect of the competition determines the size, or equivalently, the biomass of each plant and the number of seeds it produces. At the end of a period (year) plants distribute their seeds over the sites in the Moore neighbourhood and then die. They leave their biomass in the form of litter, which hinders germination of the seeds. We show that the dynamical behaviour depends crucially on two parameters-litter reduction rate and the plants' growth rate. Larger litter reduction rate and smaller growth rate lead to the population of few plants, producing more biomass than when more smaller plants are present and the litter reduction rate is low and growth rate is high. We show that asymmetry in the competition, which could favour bigger plants, have rather weak effect on the dynamical behaviour. The distribution of the biomass depends on the asymmetry. When larger plants receive much more sunlight than the smaller ones, the latter are quite often eliminated from the neighbourhood. For weaker asymmetry smaller plants could survive, producing however less biomass than the larger plants.

  16. Population identification of western hemisphere shorebirds throughout the annual cycle

    USGS Publications Warehouse

    Haig, Susan M.; Gratto-Trevor, C. L.; Mullins, Thomas D.; Colwell, M.A.

    1997-01-01

    Identification of relationships among geographically distinct populations of migratory species can provide an understanding of breeding and natal philopatry, migration pathways, and population mixing during winter. We used random amplified polymorphic DNA (RAPD) analyses to search for markers specific to difficult-to-differentiate shorebird species (e.g. long-billed dowitcher Limnodromus scolopaceus and short-billed dowitcher L. griseus) as well as geographically distinct breeding populations of Hudsonian godwits Limosa haemastica, red-necked phalaropes Phalaropus lobatus, semipalmated plovers Charadrius semipalmatus, dunlin Calidris alpina, pectoral sandpipers C. melanotos, semipalmated sandpipers C. pusilla and western sandpipers C. mauri. Markers clearly differentiated all shorebird species. Estimates of population differentiation varied greatly among species (FST= 0.095a??0.685) and correlated with interspecific variation in philopatry and geographical separation of breeding populations. We assigned individuals to putative breeding locales with greater certainty in well-differentiated species than in poorly differentiated species. Our findings indicate specific phylogeographical structure varies among species, which has strong implications for conservation of habitats within migratory corridors. We suggest that RAPDs are useful in identifying geographical populations of migratory species and that molecular markers should be considered for tracking migratory birds throughout the annual cycle.

  17. Waste Isolation Pilot Plant Annual Site Environmental Report for 2012

    SciTech Connect

    2013-09-01

    The purpose of the Waste Isolation Pilot Plant (WIPP) Annual Site Environmental Report for 2012 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1B, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data to: Characterize site environmental management performance; Summarize environmental occurrences and responses reported during the calendar year; Confirm compliance with environmental standards and requirements; Highlight significant environmental accomplishments, including progress toward the DOE Environmental Sustainability Goals made through implementation of the WIPP Environmental Management System (EMS).

  18. [Recent progress in plant molecular population genetics].

    PubMed

    Wang, Yun-Sheng; Huang, Hong-Wen; Wang, Ying

    2007-10-01

    Molecular population genetics is not only one of the most important subjects of evolutionary biology, but also the basics subject of breeding, association mapping, and linkage analysis. Molecular population genetics has been developed from the classical population genetics aiming at studying population genetic structure and the factors that affect the population genetic structure by investigating the variation of DNA sequences. Therefore, population evolving history can be deduced accurately and quantitatively for evaluating the former conclusions about long-term evolution and the stability of genetic systems. Thus, molecular population genetics can avoid the shortcomings of classical population genetics, i.e. limiting to deduce the short evolving history of a population. Moreover, understanding of molecular variation patterns leads to further evaluation of the evolution theory, which is based on "Natural Selection" and introduced by Darwin. Molecular population genetics has made great progress and revealed many important scientific issues, such as the pattern of DNA polymorphism, the level of linkage disequilibrium, demographical history, and the genetic forces affecting gene evolvement. Furthermore, new research areas have been developed from molecular population genetics and become the hot fields, such as molecular phylogeography. In this review, we summarized studies and progresses of plant molecular population genetics.

  19. Comparison studies of unsaturated flow below annual and perennial plants.

    PubMed

    Scott, Bill; Lantzke, Ross; Nicholson, Dave; Findlater, Paul

    2012-01-01

    Values of unsaturated water content determined with neutron moisture measurements (NMM) reveal different water profiles below different plantings. In the extremes, calibration requires a linear and logarithmic response (using the Lambert-W function) along with the normal submersion in a drum of water. Nevertheless a post-calibration with a hydraulic push sampler was used for confirmation. Data were collected at six pastures near the Western Australia coast near Geraldton, with four replicates through the profile. The sites have mostly sandy soils and receive 300-500 mm of rainfall annually. Findings generally showed that, if there was sufficient water, as in 2006, the perennials were able to use the water evenly throughout the vertical profile. Otherwise, with low rainfall, as in 2009, perennials struggle to survive and use less water than the annuals. Modelling of the soil water movement, plant growth and calibration/recalibration is and will be used to get a maximum likehood fit. Clearly, in desert conditions and little or no vegetation, rainfall tends to build up deep in the profile, increase salinity in groundwater, and create waterlogging. Any vegetation is helpful; perennials more so; provided they have sufficient water and are not significantly harvested.

  20. Host Plant Adaptation in Drosophila mettleri Populations

    PubMed Central

    Castrezana, Sergio; Bono, Jeremy M.

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts. PMID:22493678

  1. Host plant adaptation in Drosophila mettleri populations.

    PubMed

    Castrezana, Sergio; Bono, Jeremy M

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts.

  2. Model of yield response of corn to plant population and absorption of solar energy.

    PubMed

    Overman, Allen R; Scholtz, Richard V

    2011-01-31

    Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha(-1) and g plant(-1)) on plant population (plants m(-2)). Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L.) grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Y(m) (Mg ha(-1)) for maximum yield at high plant population and c (m(2) plant(-1)) for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, x(c) = 1/c (plants m(-2)). The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of x(c) were very similar for the three field studies with the same crop species.

  3. Genetic regulation of flowering time in annual and perennial plants.

    PubMed

    Khan, Muhammad Rehman Gul; Ai, Xiao-Yan; Zhang, Jin-Zhi

    2014-01-01

    Flowering time plays a significant role in the reproductive success of plants. So far, five major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod, vernalization, and gibberellins and autonomous floral iation, and aging by sequentially operating miRNAs (typically miR156 and miR172) responding to endogenous cues. The balance of signals from these pathways is integrated by a common set of genes (FLOWERING LOCUS C, FLOWERING LOCUS T, LEAFY, and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1) that determine the flowering time. Recent studies have indicated that epigenetic modification, alternative splicing, antisense RNA and chromatin silencing regulatory mechanisms play an important role in this process by regulating related flowering gene expression. In this review, we discuss the current understanding in genetic regulation of the phase transition from vegetative to reproductive growth by using Arabidopsis as a model. We also describe how this knowledge has been successfully applied for identifying homologous genes from perennial crops. Furthermore, detailed analysis of the similarities and differences between annual and perennial plants flowering will help elucidate the mechanisms of perennial plant maturation and regulation of floral initiation.

  4. Annual Cycle of Planktothrix agardhii (Gom.) Anagn. &Kom. Nature Population

    NASA Astrophysics Data System (ADS)

    Poulíková, Aloisie; Haler, Petr; Kitner, Miloslav

    2004-07-01

    Changes in abundance, biovolume and morphology of Planktothrix agardhii in a natural population were followed over one year period in shallow fishpond Bílá Lhota (Central Moravia, Czech Republic). The selected environmental parameters (pH, oxygen, temperature, conductivity, nutrients, light) were measured at the surface and at the bottom of the fishpond, together with the Planktothrix abundances and filament morphology - filament length, width, shape, aerotopes (gas vacuoles) formation. The annual cycle of P. agardhii in this hypertrophic fishpond starts in March with the germination of hormogonia and the growth of overwintered filaments. The filament length quickly increases to a maximum length in April. The following summer period can be characterized by filament shortening and by changes in the aerotopes shape. On the other hand the abundance and biomass of P. agardhii is increasing until the maximum in August. Further shortening of filaments, loss of aerotopes and hormogoniae formation is typical for the autumn (October) with the average temperature of 9.4 °C. The population overwinters near the pond bottom in the form of hormogonia (60%) and filaments (40%). (

  5. An empirical model for estimating annual consumption by freshwater fish populations

    USGS Publications Warehouse

    Liao, H.; Pierce, C.L.; Larscheid, J.G.

    2005-01-01

    Population consumption is an important process linking predator populations to their prey resources. Simple tools are needed to enable fisheries managers to estimate population consumption. We assembled 74 individual estimates of annual consumption by freshwater fish populations and their mean annual population size, 41 of which also included estimates of mean annual biomass. The data set included 14 freshwater fish species from 10 different bodies of water. From this data set we developed two simple linear regression models predicting annual population consumption. Log-transformed population size explained 94% of the variation in log-transformed annual population consumption. Log-transformed biomass explained 98% of the variation in log-transformed annual population consumption. We quantified the accuracy of our regressions and three alternative consumption models as the mean percent difference from observed (bioenergetics-derived) estimates in a test data set. Predictions from our population-size regression matched observed consumption estimates poorly (mean percent difference = 222%). Predictions from our biomass regression matched observed consumption reasonably well (mean percent difference = 24%). The biomass regression was superior to an alternative model, similar in complexity, and comparable to two alternative models that were more complex and difficult to apply. Our biomass regression model, log10(consumption) = 0.5442 + 0.9962??log10(biomass), will be a useful tool for fishery managers, enabling them to make reasonably accurate annual population consumption predictions from mean annual biomass estimates. ?? Copyright by the American Fisheries Society 2005.

  6. Effects of three species of Chihuahuan Desert ants on annual plants and soil properties

    USDA-ARS?s Scientific Manuscript database

    We tested the hypothesis that ant species, which occupy the same nest for a decade or longer, would modify nest soils by increasing soil nutrients and microorganisms resulting in increased biomass, density, cover and species richness of annual plants. We measured soil properties and annual plants on...

  7. Model of Yield Response of Corn to Plant Population and Absorption of Solar Energy

    PubMed Central

    Overman, Allen R.; Scholtz, Richard V.

    2011-01-01

    Biomass yield of agronomic crops is influenced by a number of factors, including crop species, soil type, applied nutrients, water availability, and plant population. This article is focused on dependence of biomass yield (Mg ha−1 and g plant−1) on plant population (plants m−2). Analysis includes data from the literature for three independent studies with the warm-season annual corn (Zea mays L.) grown in the United States. Data are analyzed with a simple exponential mathematical model which contains two parameters, viz. Ym (Mg ha−1) for maximum yield at high plant population and c (m2 plant−1) for the population response coefficient. This analysis leads to a new parameter called characteristic plant population, xc = 1/c (plants m−2). The model is shown to describe the data rather well for the three field studies. In one study measurements were made of solar radiation at different positions in the plant canopy. The coefficient of absorption of solar energy was assumed to be the same as c and provided a physical basis for the exponential model. The three studies showed no definitive peak in yield with plant population, but generally exhibited asymptotic approach to maximum yield with increased plant population. Values of xc were very similar for the three field studies with the same crop species. PMID:21297960

  8. Plant diversity, herbivory and resistance of a plant community to invasion in Mediterranean annual communities.

    PubMed

    Prieur-Richard, Anne-Hélène; Lavorel, Sandra; Linhart, Yan B; Dos Santos, Anabelle

    2002-01-01

    Several components of the diversity of plant communities, such as species richness, species composition, number of functional groups and functional composition, have been shown to directly affect the performance of exotic species. Exotics can also be affected by herbivores of the native plant community. However, these two possible mechanisms limiting invasion have never been investigated together. The aim of this study was to investigate the relationships between plant diversity, herbivory and performance of two annual exotics, Conyza bonariensis and C. canadensis, in Mediterranean annual communities. We wanted to test whether herbivory of these exotics was influenced either by species richness, functional-group richness or functional-group composition. We also studied the relationship between herbivory on the exotic species and their performance. Herbivory increased with increasing species and functional-group richness for both Conyza species. These patterns are interpreted as reflecting a greater number of available herbivore niches in a richer, more complex, plant community. The identities of functional groups also affected Conyza herbivory, which decreased in the presence of Asteraceae or Fabaceae and increased in the presence of Poaceae. Increasing herbivory had consequences for vegetative and demographic parameters of both invasive species: survival, final biomass and net fecundity decreased with increasing herbivory, leading to a loss of reproductive capacity. We conclude that communities characterised by a high number of grass species instead of Asteraceae or Fabaceae may be more resistant to invasion by the two Conyza species, in part due to predation by native herbivores.

  9. Waste Isolation Pilot Plant Annual Site Environmental Report for 2010

    SciTech Connect

    2011-09-01

    The purpose of the Waste Isolation Pilot Plant (WIPP) Annual Site Environmental Report for 2010 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1A, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data to: (1) Characterize site environmental management performance. (2) Summarize environmental occurrences and responses reported during the calendar year. (3) Confirm compliance with environmental standards and requirements. (4) Highlight significant environmental accomplishments, including progress toward the DOE Environmental Sustainability Goals made through implementation of the WIPP Environmental Management System (EMS). The DOE Carlsbad Field Office (CBFO) and the management and operating contractor (MOC), Washington TRU Solutions LLC (WTS), maintain and preserve the environmental resources at the WIPP. DOE Order 231.1A; DOE Order 450.1A, Environmental Protection Program; and DOE Order 5400.5, Radiation Protection of the Public and the Environment, require that the affected environment at and near DOE facilities be monitored to ensure the safety and health of the public and workers, and preservation of the environment. This report was prepared in accordance with DOE Order 231.1A, which requires that DOE facilities submit an ASER to the DOE Headquarters Chief Health, Safety, and Security Officer. The WIPP Hazardous Waste Facility Permit Number NM4890139088-TSDF (Permit) further requires that the ASER be provided to the New Mexico Environment Department (NMED).

  10. Waset Isolation Pilot Plant Annual Site Environmental Report for 2006

    SciTech Connect

    Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

    2007-09-26

    The purpose of the Waste Isolation Pilot Plant Annual Site Environmental Report for 2006 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1A, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data that: (a) Characterize site environmental management performance; (b) Summarize environmental occurrences and responses reported during the calendar year; (c) Confirm compliance with environmental standards and requirements; and (d) Highlight significant facility programs and efforts. The DOE Carlsbad Field Office (CBFO) and Washington TRU Solutions LLC (WTS) maintain and preserve the environmental resources at the WIPP site. DOE Order 231.1A; DOE Order 450.1, Environmental Protection Program; and DOE Order 5400.5, Radiation Protection of the Public and Environment, require that the affected environment at and near DOE facilities be monitored to ensure the safety and health of the public and the environment. This report was prepared in accordance with DOE Order 231.1A. This order requires that DOE facilities submit an ASER to the DOE Headquarters Office of the Assistant Secretary for Environment, Safety, and Health. The WIPP Hazardous Waste Facility Permit (HWFP) (No. NM4890139088-TSDF [treatment, storage, and disposal facility]) further requires that the ASER be provided to the New Mexico Environment Department (NMED).

  11. Seasonal changes in spatial patterns of two annual plants in the Chihuahuan Desert, USA

    USGS Publications Warehouse

    Yin, Z.-Y.; Guo, Q.; Ren, H.; Peng, S.-L.

    2005-01-01

    Spatial pattern of a biotic population may change over time as its component individuals grow or die out, but whether this is the case for desert annual plants is largely unknown. Here we examined seasonal changes in spatial patterns of two annuals, Eriogonum abertianum and Haplopappus gracilis, in initial (winter) and final (summer) densities. The density was measured as the number of individuals from 384 permanent quadrats (each 0.5 m × 0.5 m) in the Chihuahuan Desert near Portal, Arizona, USA. We used three probability distributions (binomial, Poisson, and negative binomial or NB) that represent three basic spatial patterns (regular, random, and clumped) to fit the observed frequency distributions of densities of the two annuals. Both species showed clear clumped patterns as characterized by the NB and had similar inverse J-shaped frequency distribution curves in two density categories. Also, both species displayed a reduced degree of aggregation from winter to summer after the spring drought (massive die-off), as indicated by the increased k-parameter of the NB and decreased values of another NB parameter p, variance/mean ratio, Lloyd’s Index of Patchiness, and David and Moore’s Index of Clumping. Further, we hypothesized that while the NB (i.e., Poisson-logarithmic) well fits the distribution of individuals per quadrat, its components, the Poisson and logarithmic, may describe the distributions of clumps per quadrat and of individuals per clump, respectively. We thus obtained the means and variances for (1) individuals per quadrat, (2) clumps per quadrat, and (3) individuals per clump. The results showed that the decrease of the density from winter to summer for each plant resulted from the decrease of individuals per clump, rather than from the decrease of clumps per quadrat. The great similarities between the two annuals indicate that our observed temporal changes in spatial patterns may be common among desert annual plants.

  12. Is plasticity across seasons adaptive in the annual cleistogamous plant Lamium amplexicaule?

    PubMed Central

    Stojanova, B.; Maurice, S.; Cheptou, P.-O.

    2016-01-01

    Background and aims Many angiosperms exhibit cleistogamy, the production of both cleistogamous flowers (CL), which remain closed and obligately self-pollinated, and chasmogamous flowers (CH), which are potentially open-pollinated. The CH proportion can be plastic. Plasticity is adaptive if environmental changes can be reliably assessed and responded to with an appropriate phenotype and if plastic genotypes have higher fitness in variable environments than non-plastic ones. Methods We studied the plastic response of four natural populations from northern and southern France of an annual cleistogamous plant, Lamium amplexicaule, to predictable seasonal variation. Plants were grown in a semi-controlled environment in spring and in autumn. We assessed the variation in flower number, phenology and cleistogamy-related traits, which were all plastic with respect to season. The CH proportion was higher in spring than in autumn in all four populations. Key Results We showed significant stabilizing selection for cleistogamy traits, with higher optimal CH proportions and more pronounced stabilizing selection in spring than in autumn. Observed CH proportions were close to the predicted optimal CH proportions in each season except in autumn for southern populations, which do not experience the autumnal growing season in nature. Conclusions These results are consistent with adaptive plasticity across seasons of cleistogamy in L. amplexicaule. We propose that adaptive plasticity of cleistogamy could be driven by pollination environment variation, with CL flowers providing reproductive assurance when pollinators are scarce and CH flowers reducing the inbreeding depression in offspring when pollinators are abundant. PMID:26995537

  13. Waste Isolation Pilot Plant Annual Site Enviromental Report for 2008

    SciTech Connect

    Washington Regulatory and Enviromnetal Services

    2009-09-21

    The purpose of the Waste Isolation Pilot Plant Annual Site Environmental Report for 2008 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1A, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data to characterize site environmental management performance; summarize environmental occurrences and responses reported during the calendar year; confirm compliance with environmental standards and requirements; highlight significant facility programs and efforts; and describe how compliance and environmental improvement is accomplished through the WIPP Environmental Management System (EMS). The DOE Carlsbad Field Office (CBFO) and the management and operating contractor (MOC), Washington TRU Solutions LLC (WTS), maintain and preserve the environmental resources at the Waste Isolation Pilot Plant (WIPP). DOE Order 231.1A; DOE Order 450.1A, Environmental Protection Program; and DOE Order 5400.5, Radiation Protection of the Public and the Environment, require that the affected environment at and near DOE facilities be monitored to ensure the safety and health of the public and workers, and preservation of the environment. This report was prepared in accordance with DOE Order 231.1A, which requires that DOE facilities submit an ASER to the DOE Headquarters Chief Health, Safety, and Security Officer. The WIPP Hazardous Waste Facility Permit (HWFP) Number NM4890139088-TSDF (treatment, storage, and disposal facility) further requires that the ASER be provided to the New Mexico Environment Department (NMED). The WIPP mission is to safely dispose of transuranic (TRU) radioactive waste generated by the production of nuclear weapons and other activities related to the national defense of the United States. In 2008, 5,265 cubic meters (m3) of TRU waste were disposed of at the WIPP facility, including 5,216 m3 of contact-handled (CH) TRU waste and 49 m3 of remote-handled (RH) TRU waste. From the first

  14. Ecological and population genetics of locally rare plants: A review

    Treesearch

    Simon A. Lei

    2001-01-01

    Plant species with limited dispersal ability, narrow geographical and physiological tolerance ranges, as well as with specific habitat and ecological requirements are likely to be rare. Small and isolated populations and species contain low levels of within-population genetic variation in many plant species. The gene pool of plants is a product of phenotype-environment...

  15. Assemblage of a semi-arid annual plant community: abiotic and biotic filters act hierarchically.

    PubMed

    Luzuriaga, Arantzazu L; Sánchez, Ana M; Maestre, Fernando T; Escudero, Adrián

    2012-01-01

    The study of species coexistence and community assembly has been a hot topic in ecology for decades. Disentangling the hierarchical role of abiotic and biotic filters is crucial to understand community assembly processes. The most critical environmental factor in semi-arid environments is known to be water availability, and perennials are usually described as nurses that create milder local conditions and expand the niche range of several species. We aimed to broaden this view by jointly evaluating how biological soil crusts (BSCs), water availability, perennial species (presence/absence of Stipa tenacissima) and plant-plant interactions shape a semi-arid annual plant community. The presence and cover of annual species was monitored during three years of contrasting climate. Water stress acted as the primary filter determining the species pool available for plant community assembly. Stipa and BSCs acted as secondary filters by modulating the effects of water availability. At extremely harsh environmental conditions, Stipa exerted a negative effect on the annual plant community, while at more benign conditions it increased annual community richness. Biological soil crusts exerted a contradictory effect depending on climate and on the presence of Stipa, favoring annuals in the most adverse conditions but showing repulsion at higher water availability conditions. Finally, interactions among co-occurring annuals shaped species richness and diversity of the final annual plant assembly. This study sheds light on the processes determining the assembly of annual communities and highlights the importance of Biological Soil Crusts and of interactions among annual plants on the final outcome of the species assembly.

  16. Bet hedging in desert winter annual plants: optimal germination strategies in a variable environment.

    PubMed

    Gremer, Jennifer R; Venable, D Lawrence

    2014-03-01

    In bet hedging, organisms sacrifice short-term success to reduce the long-term variance in success. Delayed germination is the classic example of bet hedging, in which a fraction of seeds remain dormant as a hedge against the risk of complete reproductive failure. Here, we investigate the adaptive nature of delayed germination as a bet hedging strategy using long-term demographic data on Sonoran Desert winter annual plants. Using stochastic population models, we estimate fitness as a function of delayed germination and identify evolutionarily stable strategies for 12 abundant species in the community. Results indicate that delayed germination meets the criteria as a bet hedging strategy for all species. Density-dependent models, but not density-independent ones, predicted optimal germination strategies that correspond remarkably well with observed patterns. By incorporating naturally occurring variation in seed and seedling dynamics, our results present a rigorous test of bet hedging theory within the relevant environmental context.

  17. Inter-annual variation in the foraging ecology of a brown bear population in southwest Alaska

    NASA Astrophysics Data System (ADS)

    Stricker, C. A.; Kovach, S. D.; Collins, G. H.; Farley, S. D.; Rye, R. O.; Hinkes, M. T.

    2010-12-01

    Brown bear (Ursus arctos) population size correlates with density of high-quality food resources. We report on a ten-year study (1993 - 2003) of brown bear nutritional ecology in southwestern Alaska during which changes in resource availability and density occurred. The diets of 21 female bears captured multiple years were characterized by stable isotope analysis (δ13C, δ15N, and δ34S) of guard hairs and putative diet items, followed by application of a Bayesian mixing model to derive assimilated diet estimates. Diet estimates were subsequently used to characterize individual-level resource specialization. Over the entire study period, salmon accounted for the highest proportion of bear diets (42.1%), followed by berries (24.5%), mammals (13.5%), freshwater fish (11.2%), and other plant matter (8.7%). The average salmon contribution to bear diets declined significantly from 48% to 34% following a precipitous reduction in salmon escapement mid-way through the study, after which the bear population shifted toward a more generalist diet. However, evaluation of individual animals recaptured multiple times during the study revealed variation in inter-annual dietary habits unrelated to the salmon crash. Individual variation presumably reflects local density changes in a variety of resources, with concomitant annual shifts in the degree of individual specialization. We also relate these patterns to other individual traits, such as reproductive status, home range, and habitat use to better constrain foraging habits. This study provides unique insights into the nutritional ecology of Alaskan brown bears and complements traditional wildlife studies by offering important covariates to better understand changes in population vital rates.

  18. Coexistence of annual plants: generalist seed predation weakens the storage effect.

    PubMed

    Kuang, Jessica J; Chesson, Peter

    2009-01-01

    We investigate the effect of seed predation on the coexistence of competing annual plants. We demonstrate a role for predation that is opposite to the conventional wisdom that predation promotes coexistence by reducing the intensity of competition. In the common situation where competitive coexistence involves intraspecific competition exceeding interspecific competition, predation can undermine coexistence by reducing the overall magnitude of competition, replacing competition with "apparent competition" in a way that does not lead to differential intraspecific and interspecific effects. We demonstrate this outcome in the case where coexistence occurs by "the storage effect" in a variable environment. The storage effect arises when the environment interacts with competition to create opportunities for species to increase from low density. Critical to the storage effect is positive covariance between the response of population growth to the environment and its response to competition, when a species is at high density. This outcome prevents species at high density from taking advantage of favorable environmental conditions. A species at low density has lower covariance and can take advantage of favorable environmental conditions, giving it an advantage over a high-density species, fostering its recovery from low density. Hence, species coexistence is promoted. Here we find that density-dependent predation lowers population densities, and so weakens competition, replacing competition with apparent competition, which does not covary with the environment. As a consequence, covariance between environment and competition is weakened, reducing the advantage to a species at low density. The species still strongly interact through the combination of competition and apparent competition, but the reduced low-density advantage reduces their ability to coexist. Although this result is demonstrated specifically for the storage effect with a focus on annual plant communities

  19. 78 FR 54622 - Proposed Information Collection; Comment Request; Current Population Survey, Annual Social and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-05

    ... Census Bureau Proposed Information Collection; Comment Request; Current Population Survey, Annual Social..., March, and April Current Population Survey (CPS). The Census Bureau has conducted this supplement... country as a whole, and selected population groups of interest. Government planners and researchers use...

  20. Peak fire temperatures and effects on annual plants in the Mojave Desert

    USGS Publications Warehouse

    Brooks, Matthew L.

    2002-01-01

    Very little is known about the behavior and effects of fire in the Mojave Desert, because fire was historically uncommon. However, fire has become more frequent since the 1970s with increased dominance of the invasive annual grasses Bromus rubens and Schismus spp., and land managers are concerned about its ecological effect. In this paper, I describe patterns of peak fire temperature and their effect on annual plants in creosote bush scrub vegetation of the Mojave Desert. Temperatures were monitored among microhabitats and distances from the soil surface, and between spring and summer. Microhabitats ranged from high amounts of fuel beneath creosote bush (Larrea tridentata) canopies, to intermediate amounts at the canopy drip line, to low amounts in the interspaces between them. Distances from the soil surface were within the vertical range where most annual plant seeds occur (−2, 0, 5, and 10 cm). I also compare temperature patterns with postfire changes in soil properties and annual plant biomass and species richness to infer potential mechanisms by which fires affect annual plants.Peak fire temperatures were most affected by the microhabitat fuel gradient, and the effects of fire on annual plants varied among microhabitats. Beneath creosote bushes, lethal fire temperatures for annual plant seeds occurred above- and belowground, resulting in four postfire years of reduced annual plant biomass and species richness due most likely to seed mortality, especially of Bromus rubens and native forbs. At the canopy drip line, lethal fire temperatures occurred only aboveground, reducing annual plant biomass for 1 yr and species richness for 2 yr, and increasing biomass of Schismus sp., the alien forb Erodium cicutarium, and native annuals after 3 yr. Negligible changes were caused by fire in interspaces or between spring and summer.Fire effects models for creosote bush scrub vegetation must account for patterns of peak fire temperature along the shrub

  1. Managing Natural and Reintroduced Rare Plant Populations within a Large Government Reservation

    SciTech Connect

    Carlsen, T M; Paterson, L E; Alfaro, T M

    2009-07-15

    California is home to many large government reservations that have been in existence for decades. Many of these reservations were formed to support various Department of Defense and Department of Energy national defense activities. Often, only a very small percentage of the reservation is actively used for programmatic activities, resulting in large areas of intact habitat. In some cases, this has benefited rare plant populations, as surrounding lands have been developed for residential or industrial use. However, land management activities such as the suppression or active use of fire and other disturbance (such as fire trail grading) can also work to either the detriment or benefit of rare plant populations at these sites. A management regime that is beneficial to the rare plant populations of interest and is at best consistent with existing site programmatic activities, and at a minimum does not impact such activities, has the best potential for a positive outcome. As a result, some species may be 'difficult' while others may be 'easy' to manage in this context, depending on how closely the species biological requirements match the programmatic activities on the reservation. To illustrate, we compare and contrast two rare annual plant species found at Lawrence Livermore National Laboratory's Site 300. Although several populations of Amsinckia grandiflora have been restored on the site, and all populations are intensively managed, this species continues to decline. In contrast, Blepharizonia plumosa appears to take advantage of the annual controlled burns conducted on the site, and is thriving.

  2. Gene Flow and the Measurement of Dispersal in Plant Populations.

    ERIC Educational Resources Information Center

    Nicholls, Marc S.

    1986-01-01

    Reviews methods of estimating pollen and seed dispersals and discusses the extent and frequency of gene exchange within and between populations. Offers suggestions for designing exercises suitable for estimating dispersal distances in natural plant populations. (ML)

  3. Gene Flow and the Measurement of Dispersal in Plant Populations.

    ERIC Educational Resources Information Center

    Nicholls, Marc S.

    1986-01-01

    Reviews methods of estimating pollen and seed dispersals and discusses the extent and frequency of gene exchange within and between populations. Offers suggestions for designing exercises suitable for estimating dispersal distances in natural plant populations. (ML)

  4. An annual plant growth proxy in the Mojave Desert using MODIS-EVI data

    USGS Publications Warehouse

    Wallace, C.S.A.; Thomas, K.A.

    2008-01-01

    In the arid Mojave Desert, the phenological response of vegetation is largely dependent upon the timing and amount of rainfall, and maps of annual plant cover at any one point in time can vary widely. Our study developed relative annual plant growth models as proxies for annual plant cover using metrics that captured phenological variability in Moderate-Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) satellite images. We used landscape phenologies revealed in MODIS data together with ecological knowledge of annual plant seasonality to develop a suite of metrics to describe annual growth on a yearly basis. Each of these metrics was applied to temporally-composited MODIS-EVI images to develop a relative model of annual growth. Each model was evaluated by testing how well it predicted field estimates of annual cover collected during 2003 and 2005 at the Mojave National Preserve. The best performing metric was the spring difference metric, which compared the average of three spring MODIS-EVI composites of a given year to that of 2002, a year of record drought. The spring difference metric showed correlations with annual plant cover of R2 = 0.61 for 2005 and R 2 = 0.47 for 2003. Although the correlation is moderate, we consider it supportive given the characteristics of the field data, which were collected for a different study in a localized area and are not ideal for calibration to MODIS pixels. A proxy for annual growth potential was developed from the spring difference metric of 2005 for use as an environmental data layer in desert tortoise habitat modeling. The application of the spring difference metric to other imagery years presents potential for other applications such as fuels, invasive species, and dust-emission monitoring in the Mojave Desert.

  5. An Annual Plant Growth Proxy in the Mojave Desert Using MODIS-EVI Data

    PubMed Central

    Wallace, Cynthia S.A.; Thomas, Kathryn A.

    2008-01-01

    In the arid Mojave Desert, the phenological response of vegetation is largely dependent upon the timing and amount of rainfall, and maps of annual plant cover at any one point in time can vary widely. Our study developed relative annual plant growth models as proxies for annual plant cover using metrics that captured phenological variability in Moderate-Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) satellite images. We used landscape phenologies revealed in MODIS data together with ecological knowledge of annual plant seasonality to develop a suite of metrics to describe annual growth on a yearly basis. Each of these metrics was applied to temporally-composited MODIS-EVI images to develop a relative model of annual growth. Each model was evaluated by testing how well it predicted field estimates of annual cover collected during 2003 and 2005 at the Mojave National Preserve. The best performing metric was the spring difference metric, which compared the average of three spring MODIS-EVI composites of a given year to that of 2002, a year of record drought. The spring difference metric showed correlations with annual plant cover of R2 = 0.61 for 2005 and R2 = 0.47 for 2003. Although the correlation is moderate, we consider it supportive given the characteristics of the field data, which were collected for a different study in a localized area and are not ideal for calibration to MODIS pixels. A proxy for annual growth potential was developed from the spring difference metric of 2005 for use as an environmental data layer in desert tortoise habitat modeling. The application of the spring difference metric to other imagery years presents potential for other applications such as fuels, invasive species, and dust-emission monitoring in the Mojave Desert. PMID:27873958

  6. Inherited variability in multiple traits determines fitness in populations of an annual legume from contrasting latitudinal origins.

    PubMed

    Milla, Rubén; Escudero, Adrián; Iriondo, Jose María

    2009-06-01

    Variation in fitness depends on corresponding variation in multiple traits which have both genetically controlled and plastic components. These traits are subjected to varying degrees of local adaptation in specific populations and, consequently, are genetically controlled to different extents. In this study it is hypothesized that modulation of different traits would have contrasting relevance for the fitness of populations of diverse origins. Specifically, assuming that environmental pressures vary across a latitudinal gradient, it is suggested that inherited variation in traits differentially determines fitness in annual Lupinus angustifolius populations from contrasting latitudinal origins in western Spain. Seeds of L. angustifolius from three contrasting origins were grown in a common garden. Traits related to more plastic vegetative growth and more genetically conserved phenology were measured, together with estimates of reproductive success. Fitness was estimated by the number of viable seeds per plant. Structural Equation Models were used to infer causal relationships among multiple traits and fitness, separating the direct and indirect effects of morphological, phenological and reproductive traits. Phenological, vegetative and reproductive traits accounted for most of the fitness variation. Fitness was highest in plants of southernmost origin, mainly due to earlier flowering. Fitness within each seed origin was controlled by variation in different traits. Southern origin plants that grew to a larger size achieved higher fitness. However, plant size in plants of northernmost origin was irrelevant, but early flowering promoted higher fitness. Variation in fruit and seed set had a greater effect on the fitness of plants of central origin than phenological and size variation. It is concluded that modulation of a functional trait can be relevant to fitness in a given population (i.e. affecting intensity and direction), but irrelevant in other populations. This

  7. Inherited variability in multiple traits determines fitness in populations of an annual legume from contrasting latitudinal origins

    PubMed Central

    Milla, Rubén; Escudero, Adrián; Iriondo, Jose María

    2009-01-01

    Background and Aims Variation in fitness depends on corresponding variation in multiple traits which have both genetically controlled and plastic components. These traits are subjected to varying degrees of local adaptation in specific populations and, consequently, are genetically controlled to different extents. In this study it is hypothesized that modulation of different traits would have contrasting relevance for the fitness of populations of diverse origins. Specifically, assuming that environmental pressures vary across a latitudinal gradient, it is suggested that inherited variation in traits differentially determines fitness in annual Lupinus angustifolius populations from contrasting latitudinal origins in western Spain. Methods Seeds of L. angustifolius from three contrasting origins were grown in a common garden. Traits related to more plastic vegetative growth and more genetically conserved phenology were measured, together with estimates of reproductive success. Fitness was estimated by the number of viable seeds per plant. Structural Equation Models were used to infer causal relationships among multiple traits and fitness, separating the direct and indirect effects of morphological, phenological and reproductive traits. Key Results Phenological, vegetative and reproductive traits accounted for most of the fitness variation. Fitness was highest in plants of southernmost origin, mainly due to earlier flowering. Fitness within each seed origin was controlled by variation in different traits. Southern origin plants that grew to a larger size achieved higher fitness. However, plant size in plants of northernmost origin was irrelevant, but early flowering promoted higher fitness. Variation in fruit and seed set had a greater effect on the fitness of plants of central origin than phenological and size variation. Conclusions It is concluded that modulation of a functional trait can be relevant to fitness in a given population (i.e. affecting intensity and

  8. A comparative study of AMF diversity in annual and perennial plant species from semiarid gypsum soils.

    NASA Astrophysics Data System (ADS)

    Alguacil, M. M.; Torrecillas, E.; Roldán, A.; Díaz, G.; Torres, P.

    2012-04-01

    The arbuscular mycorrhizal fungi (AMF) communities composition regulate plant interactions and determine the structure of plant communities. In this study we analysed the diversity of AMF in the roots of two perennial gypsophyte plant species, Herniaria fruticosa and Senecio auricula, and an annual herbaceous species, Bromus rubens, growing in a gypsum soil from a semiarid area. The objective was to determine whether perennial and annual host plants support different AMF communities in their roots and whether there are AMF species that might be indicators of specific functional plant roles in these ecosystems. The roots were analysed by nested PCR, cloning, sequencing of the ribosomal DNA small subunit region and phylogenetic analysis. Twenty AMF sequence types, belonging to the Glomus group A, Glomus group B, Diversisporaceae, Acaulosporaceae, Archaeosporaceae and Paraglomeraceae, were identified. Both gypsophyte perennial species had differing compositions of the AMF community and higher diversity when compared with the annual species, showing preferential selection by specific AMF sequences types. B. rubens did not show host specificity, sharing the full composition of its AMF community with both perennial plant species. Seasonal variations in the competitiveness of AM fungi could explain the observed differences in AMF community composition, but this is still a working hypothesis that requires the analysis of further data obtained from a higher number of both annual and perennial plant species in order to be fully tested.

  9. Small Variance in Growth Rate in Annual Plants has Large Effects on Genetic Drift

    USDA-ARS?s Scientific Manuscript database

    When plant size is strongly correlated with plant reproduction, variance in growth rates results in a lognormal distribution of seed production within a population. Fecundity variance affects effective population size (Ne), which reflects the ability of a population to maintain beneficial mutations ...

  10. Pinellas Plant Annual Site Environmental Report for calendar year 1994

    SciTech Connect

    1995-06-01

    This report presents a comprehensive summary of the results of the Environmental Monitoring, Waste Management, and Environmental Restoration Programs at the Pinellas Plant, in Pinellas County, Florida for 1994. This report also includes the plant`s performance in the areas of compliance with applicable regulatory requirements and standards and identifies major Environmental, Safety and Health Program initiatives and accomplishments for 1994. As a result of the end of Department of Energy Defense Programs mission production on September 30, 1994, considerable changes at the Pinellas Plant occurred. These changes, which included transitioning the plant toward alternate use in support of economic development and safe shutdown, both increased and heightened Environmental, Safety and Health responsibilities. In December 1994, the Department of Energy announced it had reached an agreement to sell the Pinellas Plant to the Pinellas County Industry Council in March 1995. The plant is being leased back by the Department of Energy through September 1997 to complete safe shutdown, reconfiguration, transfer of equipment to other Department of Energy production facilities, and transition to commercial ventures. Permit modifications and transfers will be completed during 1995 to reflect the new ownership by the Pinellas County Industry Council and to include new tenants as needed.

  11. Optimal phenology of annual plants under grazing pressure.

    PubMed

    Yamamura, Norio; Fujita, Noboru; Hayashi, Motoyuki; Nakamura, Yusuke; Yamauchi, Atsushi

    2007-06-07

    Plants show phenological responses to herbivory. Some enclosure experiments have demonstrated that the onset of the peak flowering season is dependent on grazing pressure. We constructed a mathematical model using Pontryargin's maximum principle to investigate changes in flowering time by examining shifts in resource allocation from vegetative to reproductive plant components. We represented a primary production of a plant individual by two types of function of vegetative part size, a linear function and a convex non-linear function. The results of a linear production model indicate that optimal phenology follows a schedule that switches from the production of vegetative parts to that of reproductive parts at a given time ('bang-bang' control). However, in a non-linear model, a singular control, wherein the plant invests in both productive and reproductive parts, may be included between obligate production and reproduction periods. We assumed that the peak of the flowering season occurs immediately following the exclusive investment in reproduction. In a linear production model, differential herbivory rates on the vegetative and reproductive parts of a plant resulted in shifts in the peak flowering time. A higher herbivory rate on the vegetative components advanced the peak, whereas it was delayed when grazing pressure focused on reproductive components of the plant. In the non-linear production model, increased grazing pressure tended to postpone the flowering peak. These results corresponded well with results of enclosure experiments, thus suggesting adaptive control of flowering time in plants.

  12. Radioactive materials released from nuclear power plants: Annual report, 1984

    SciTech Connect

    Tichler, J.; Norden, K.; Congemi, J.

    1987-08-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1984 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1984 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  13. Radioactive materials released from nuclear power plants: Annual report, 1985

    SciTech Connect

    Tichler, J.; Norden, K.; Congemi, J.

    1988-01-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1985 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1985 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  14. Radioactive materials released from nuclear power plants. Annual report 1978

    SciTech Connect

    Tichler, J.; Benkovitz, C.

    1981-03-01

    Releases of radioactive materials in airborne and liquid effluents from commerical light water reactors during 1978 have been compiled and reported. Data on soild waste shipments as well as selected operating information have been included. This report supplements earlier annual reports by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1978 release data are compared with previous years releases in tabular form. Data covering specific radionuclides are summarized.

  15. Unravelling the annual cycle in a migratory animal: breeding-season habitat loss drives population declines of monarch butterflies.

    PubMed

    Flockhart, D T Tyler; Pichancourt, Jean-Baptiste; Norris, D Ryan; Martin, Tara G

    2015-01-01

    Threats to migratory animals can occur at multiple periods of the annual cycle that are separated by thousands of kilometres and span international borders. Populations of the iconic monarch butterfly (Danaus plexippus) of eastern North America have declined over the last 21 years. Three hypotheses have been posed to explain the decline: habitat loss on the overwintering grounds in Mexico, habitat loss on the breeding grounds in the United States and Canada, and extreme weather events. Our objectives were to assess population viability, determine which life stage, season and geographical region are contributing the most to population dynamics and test the three hypotheses that explain the observed population decline. We developed a spatially structured, stochastic and density-dependent periodic projection matrix model that integrates patterns of migratory connectivity and demographic vital rates across the annual cycle. We used perturbation analysis to determine the sensitivity of population abundance to changes in vital rate among life stages, seasons and geographical regions. Next, we compared the singular effects of each threat to the full model where all factors operate concurrently. Finally, we generated predictions to assess the risk of host plant loss as a result of genetically modified crops on current and future monarch butterfly population size and extinction probability. Our year-round population model predicted population declines of 14% and a quasi-extinction probability (<1000 individuals) >5% within a century. Monarch abundance was more than four times more sensitive to perturbations of vital rates on the breeding grounds than on the wintering grounds. Simulations that considered only forest loss or climate change in Mexico predicted higher population sizes compared to milkweed declines on the breeding grounds. Our model predictions also suggest that mitigating the negative effects of genetically modified crops results in higher population size and

  16. Genetic comparisons between seed bank and Stipa krylovii plant populations.

    PubMed

    Han, B; Zhao, M

    2011-09-01

    The soil seed bank represents the potential plant population since it is the source for population replacement. The genetic structure of a Stipa krylovii (Roshev.) plant population and its soil seed bank was investigated in the Xilinguole Steppe of Inner Mongolia using random amplified polymorphic DNA (RAPD) analyses. The population was sampled at two sites that were in close proximity to each other (0.5 km apart). Thirty plants and 18 seed bank samples were taken from each site to determine the genetic diversity between sites and between sources (plant or seed). The material was analyzed using 13 primers to produce 92 loci. Eighty-six were multi-loci, of which 23 loci (26.74%) of allele frequencies showed significant differences (P < or = 0.05). The genetic similarity between two seed bank sites was 0.9843 while the genetic similarity between two plant sites was 0.9619. Their similarities were all greater than that between the seed bank and plant populations. An analysis of their genetic structure showed that 87.86% of total variation was derived by two-loci. Genetic structures between plant and soil seed bank populations in S. krylovii were different due to the variance of mean gametic disequilibria and mean gene diversity. AMOVA results showed that the majority of variance (88.62%) occurred within sites, 12.75% was from between-groups. Further research is needed to investigate the selective function in maintaining the genetic diversity of Stipa krylovii plant populations.

  17. Cotton Planting Date and Plant Population Effects on Yield and Quality in the Mississippi Delta

    USDA-ARS?s Scientific Manuscript database

    Cotton producers in the Mississippi Delta plant in early spring, but wet, cold weather often develops then and may reduce plant population directly or indirectly. Producers must occasionally decide if replanting is necessary. The objective of these studies was to determine planting date and plant ...

  18. [Rare plant species: floristic, phytocoenotic and population approach].

    PubMed

    Zlobin, Iu A

    2011-01-01

    The system of concepts used when estimating the rarity of plants is analyzed and the basic categories of rarity are defined, namely: true, diffuse, peripheral and temporal. The insufficiency of scientific information on ecological and coenotic relationships of rare plants is demonstrated and the necessity of a complex assessment of population system of a rare plant species is substantiated. The importance and limitations of the information on rare plants contained in the Red Books and the Red Lists for phytosozological practice is discussed.

  19. Heavy metal pumps in plants. 1997 annual progress report

    SciTech Connect

    Harper, J.F.

    1997-01-01

    'Plants have been proposed as a bioremediation tool to help remove toxic heavy metals from contaminated land and water. However, little is known about how plants take up heavy metals from the soil and transport them to different parts of the plant. An important long term goal is to understand how heavy metals, such as copper and cadmium, are transported across the plasma membrane of plant cells. The proposed research is focused on a putative heavy metal uptake pump, AXA2p [Arabidopsis X (unknown heavy metal) ATPase, isoform 2 protein], identified in a model plant, Arabidopsis. AXA belongs to a super-family of ion-translocating P-type ATPases and is the first heavy metal pump cloned from plants. AXA2 is most similar to a subfamily of pumps recently identified in bacteria, yeast and humans which appear to pump heavy metals such as copper and cadmium. Three specific aims are proposed: (1) Determine the ion specificity of the AXA2 pump, (2) Determine how pumping activity is regulated, and (3) Determine if an increased uptake of specific heavy metals can be achieved by engineering a transgenic plant with a hyper-active pump. The hypothesis being tested is that AXA2 encodes a high affinity uptake pump for copper, with lower affinity for metals such as cadmium, zinc and nickel. Fundamental research on heavy metal transporters may eventually permit transgenic plants to be engineered with specific heavy metal uptake systems useful for bioremediation. The long term goal of the proposed research is to understand how heavy metals, such as copper and cadmium, are taken up from the soil and translocated throughout the plant. The focus is on a putative heavy metal pump, AXA2p [Arabidopsis X (unknown heavy metal) ATPase, isoform 2 protein], identified in a model plant, Arabidopsis. AXA2 belongs to a large family of ion-translocating P-type ATPases. AXA2p is the first heavy metal pump cloned from plants and is most similar to a subfamily of heavy metal pumps recently identified in

  20. Understanding and Combating the Fire-Enhancing Impact of Non-Native Annuals in Desert Scrub through the Tools of Population and Landscape Ecology

    DTIC Science & Technology

    2015-05-01

    FINAL REPORT Understanding and Combating the Fire -Enhancing Impact of Non-Native Annuals in Desert Scrub through the Tools of Population and...2015 2. REPORT TYPE Final Report 3. DATES COVERED (From - To) 2/2010 - 5/2015 4. TITLE AND SUBTITLE Understanding and Combating the Fire ...gain an understanding of the landscape-scale population dynamics of fire promoting and fire retarding plant species; (2) test the hypothesis that once

  1. Projecting the success of plant restoration with population viability analysis

    USGS Publications Warehouse

    Bell, T.J.; Bowles, M.L.; McEachern, A.K.; Brigham, C.A.; Schwartz, M.W.

    2003-01-01

    Conserving viable populations of plant species requires that they have high probabilities of long-term persistence within natural habitats, such as a chance of extinction in 100 years of less than 5% (Menges 1991, 1998; Brown 1994; Pavlik 1994; Chap. 1, this Vol.). For endangered and threatened species that have been severely reduces in range and whose habitats have been fragmented, important species conservation strategies may include augmenting existing populations or restoring new viable populations (Bowles and Whelan 1994; Chap. 2, this Vol.). Restoration objectives may include increasing population numbers to reduce extinction probability, deterministic manipulations to develop a staged cohort structure, or more complex restoration of a desired genetic structure to allow outcrossing or increase effective population size (DeMauro 1993, 1994; Bowles et al. 1993, 1998; Pavlik 1994; Knapp and Dyer 1998; Chap. 2, this Vol.). These efforts may require translocation of propagules from existing (in situ) populations, or from ex situ botanic gardens or seed storage facilities (Falk et al. 1996; Guerrant and Pavlik 1998; Chap. 2, this Vol.). Population viability analysis (PVA) can provide a critical foundation for plant restoration, as it models demographic projections used to evaluate the probability of population persistence and links plant life history with restoration strategies. It is unknown how well artificially created populations will meet demographic modeling requirements (e.g., due to artificial cohort transitions) and few, if any, PVAs have been applied to restorations. To guide application of PVA to restored populations and to illustrate potential difficulties, we examine effects of planting different life stages, model initial population sizes needed to achieve population viability, and compare demographic characteristics between natural and restored populations. We develop and compare plant population restoration viability analysis (PRVA) case studies of

  2. Plant genotypic diversity increases population size of a herbivorous insect

    PubMed Central

    Utsumi, Shunsuke; Ando, Yoshino; Craig, Timothy P.; Ohgushi, Takayuki

    2011-01-01

    It is critical to incorporate the process of population dynamics into community genetics studies to identify the mechanisms of the linkage between host plant genetics and associated communities. We studied the effects of plant genotypic diversity of tall goldenrod Solidago altissima on the population dynamics of the aphid Uroleucon nigrotuberculatum. We found genotypic variation in plant resistance to the aphid in our experiments. To determine the impact of plant genotypic diversity on aphid population dynamics, we compared aphid densities under conditions of three treatments: single-genotype plots, mixed-genotype plots and mixed-genotype-with-cages plots. In the latter treatment plants were individually caged to prevent natural enemy attack and aphid movement among plants. The synergistic effects of genotypes on population size were demonstrated by the greater aphid population size in the mixed-genotype treatment than expected from additive effects alone. Two non-exclusive hypotheses are proposed to explain this pattern. First, there is a source–sink relationship among plant genotypes: aphids move from plant genotypes where their reproduction is high to genotypes where their reproduction is low. Second, natural enemy mortality is reduced in mixed plots in a matrix of diverse plant genotypes. PMID:21378084

  3. Effects of precipitation change and neighboring plants on population dynamics of Bromus tectorum.

    PubMed

    Prevéy, Janet S; Seastedt, Timothy R

    2015-11-01

    Shifting precipitation patterns resulting from global climate change will influence the success of invasive plant species. In the Front Range of Colorado, Bromus tectorum (cheatgrass) and other non-native winter annuals have invaded grassland communities and are becoming more abundant. As the global climate warms, more precipitation may fall as rain rather than snow in winter, and an increase in winter rain could benefit early-growing winter annuals, such as B. tectorum, to the detriment of native species. In this study we measured the effects of simulated changes in seasonal precipitation and presence of other plant species on population growth of B. tectorum in a grassland ecosystem near Boulder, Colorado, USA. We also performed elasticity analyses to identify life transitions that were most sensitive to precipitation differences. In both study years, population growth rates were highest for B. tectorum growing in treatments receiving supplemental winter precipitation and lowest for those receiving the summer drought treatment. Survival of seedlings to flowering and seed production contributed most to population growth in all treatments. Biomass of neighboring native plants was positively correlated with reduced population growth rates of B. tectorum. However, exotic plant biomass had no effect on population growth rates. This study demonstrates how interacting effects of climate change and presence of native plants can influence the population growth of an invasive species. Overall, our results suggest that B. tectorum will become more invasive in grasslands if the seasonality of precipitation shifts towards wetter winters and allows B. tectorum to grow when competition from native species is low.

  4. (Carbon isotope fractionation in plants): Annual technical progress report

    SciTech Connect

    O'Leary, M.H.

    1988-01-01

    Plants fractionate carbon isotopes during photosynthesis in ways which reflect photosynthetic pathway and environment. The fractionation is product of contributions from diffusion, carboxylation and other factors which can be understood using models which have been developed in our work. The object of our work is to use this fractionation to learn about the factors which control the efficiency of photosynthesis. Unlike previous studies, we do not rely principally on combustion methods, but instead develop more specific methods with substantially higher resolving power. We have recently developed a new short-term method for studying carbon isotope fractionation which promises to provide a level of detail about temperature, species, and light intensity effects on photosynthesis which has not been available until now. We are studying the isotopic compositions of metabolites (particularly aspartic acid) in C/sub 3/ plants in order to determine the role of phosphoenolpyruvate carboxylase in C/sub 3/ photosynthesis. We are studying the relative roles of diffusion and carboxylation in nocturnal CO/sub 2/ fixation in CAM plants. We are studying the use of isotopic content as an index of water-use efficiency in C/sub 3/ plants. We are developing new methods for studying carbon metabolism in plants. 3 refs

  5. Heavy metal pumps in plants. 1998 annual progress report

    SciTech Connect

    Harper, J.F.

    1998-06-01

    'The purpose of the proposed DOE research is to determine the function of AMA1, a novel heavy metal pump identified in a model plant system, Arabidopsis. Heavy metal pumps belong to a superfamily of P-type ATPases which include the plasma membrane Na/K-ATPase in animals and the plasma membrane H + ATPase in plants and fungi. Heavy metal pumps have been implicated in heavy metal resistance (e.g., cadmium) and regulation of essential micronutrients (e.g., copper). Although several heavy metal pumps have now been identified in plants, their isoform specific functions have not been investigated. The results suggest that AMA1 is a molydenum uptake pump. The authors are exploring the possibility to engineer the ion specificity of these pumps to take up other heavy metals from the soil. This report summarizes work after 2 years of a 3 year project.'

  6. Radioactive Effluents from Nuclear Power Plants Annual Report 2008

    SciTech Connect

    U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation

    2010-12-10

    This report describes radioactive effluents from commercial nuclear power plants (NPPs) in the United States. This information was reported by the licensees for radioactive discharges that occurred in 2008. The report provides information relevant to the potential impact of NPPs on the environment and on public health.

  7. Radioactive Effluents from Nuclear Power Plants Annual Report 2007

    SciTech Connect

    U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation

    2010-12-10

    This report describes radioactive effluents from commercial nuclear power plants (NPPs) in the United States. This information was reported by the licensees for radioactive discharges that occurred in 2007. The report provides information relevant to the potential impact of NPPs on the environment and on public health.

  8. Dominance and environmental correlates of alien annual plants in the Mojave Desert, USA

    USGS Publications Warehouse

    Brooks, M.L.; Berry, K.H.

    2006-01-01

    Land managers are concerned about the negative effects of alien annual plants on native plants, threatened and endangered species such as the desert tortoise (Gopherus agassizii), and ecosystem integrity in the Mojave Desert. Management of alien plants is hampered by a lack of information regarding the dominance and environmental correlates of these species. The results of this study indicate that alien plant species comprised a small fraction of the total annual plant flora, but most of the annual plant community biomass. When rainfall was high in 1995, aliens comprised 6% of the flora and 66% of the biomass. When rainfall was low in 1999, aliens comprised 27% of the flora and 91% of the biomass. Bromus rubens, Schismus spp. (S. arabicus and S. barbatus), and Erodium cicutarium were the predominant alien species during both years, comprising 99% of the alien biomass. B. rubens was more abundant in relatively mesic microhabitats beneath shrub canopies and at higher elevations above 800-1000 m, whereas Schismus spp. and E. cicutarium were more abundant in the relatively arid interspaces between shrubs, and, for Schismus spp., at lower elevations as well. Disturbance variables were more reliable indicators of alien dominance than were productivity or native plant diversity variables, although relationships often varied between years of contrasting rainfall. The strongest environmental correlates occurred between dirt road density and alien species richness and biomass of E. cicutarium, and between frequency and size of fires and biomass of B. rubens.

  9. Plant growth-promoting Burkholderia species isolated from annual ryegrass in Portuguese soils.

    PubMed

    Castanheira, N; Dourado, A C; Kruz, S; Alves, P I L; Delgado-Rodríguez, A I; Pais, I; Semedo, J; Scotti-Campos, P; Sánchez, C; Borges, N; Carvalho, G; Barreto Crespo, M T; Fareleira, P

    2016-03-01

    To search for culturable Burkholderia species associated with annual ryegrass in soils from natural pastures in Portugal, with plant growth-promoting effects. Annual ryegrass seedlings were used to trap Burkholderia from two different soils in laboratory conditions. A combined approach using genomic fingerprinting and sequencing of 16S rRNA and recA genes resulted in the identification of Burkholderia strains belonging to the species Burkholderia graminis, Burkholderia fungorum and the Burkholderia cepacia complex. Most strains were able to solubilize mineral phosphate and to synthesize indole acetic acid; some of them could produce siderophores and antagonize the phytopathogenic oomycete, Phytophthora cinnamomi. A strain (G2Bd5) of B. graminis was selected for gnotobiotic plant inoculation experiments. The main effects were the stimulation of root growth and enhancement of leaf lipid synthesis and turnover. Fluorescence in situ hybridization and confocal laser microscopy evidenced that strain G2Bd5 is a rhizospheric and endophytic colonizer of annual ryegrass. This work revealed that annual ryegrass can naturally associate with members of the genus Burkholderia. A novel plant growth promoting strain of B. graminis was obtained. The novel strain belongs to the plant-associated Burkholderia cluster and is a promising candidate for exploitation as plant inoculant in field conditions. © 2015 The Society for Applied Microbiology.

  10. Models of plant populations and communities

    SciTech Connect

    Huston, M.

    1990-01-01

    This document is the overview of the plant section in the book, {und Individual-Based Models and Approaches in Ecology}. A brief description of each of the chapters is provided, as well as a comparison of the models presented in each chapter. Four of the six chapters deal with single species interactions, one dealt with a two species system (plants and pollinators) and one deals with multispecies interactions. Both i-state distribution models and i-state configuration models are discussed. (MHB)

  11. Annual survival rate estimate of satellite transmitter–marked eastern population greater sandhill cranes

    USGS Publications Warehouse

    Fronczak, David L.; Andersen, David E.; Hanna, Everett E.; Cooper, Thomas R.

    2015-01-01

    Several surveys have documented the increasing population size and geographic distribution of Eastern Population greater sandhill cranes Grus canadensis tabida since the 1960s. Sport hunting of this population of sandhill cranes started in 2012 following the provisions of the Eastern Population Sandhill Crane Management Plan. However, there are currently no published estimates of Eastern Population sandhill crane survival rate that can be used to inform harvest management. As part of two studies of Eastern Population sandhill crane migration, we deployed solar-powered global positioning system platform transmitting terminals on Eastern Population sandhill cranes (n  =  42) at key concentration areas from 2009 to 2012. We estimated an annual survival rate for Eastern Population sandhill cranes from data resulting from monitoring these cranes by using the known-fates model in the MARK program. Estimated annual survival rate for adult Eastern Population sandhill cranes was 0.950 (95% confidence interval  =  0.885–0.979) during December 2009–August 2014. All fatalities (n  =  5) occurred after spring migration in late spring and early summer. We were unable to determine cause of death for crane fatalities in our study. Our survival rate estimate will be useful when combined with other population parameters such as the population index derived from the U.S. Fish and Wildlife Service fall survey, harvest, and recruitment rates to assess the effects of harvest on population size and trend and evaluate the effectiveness of management strategies.

  12. A computer program for estimating fish population sizes and annual production rates

    SciTech Connect

    Railsback, S.F.; Holcomb, B.D.; Ryon, M.G.

    1989-10-01

    This report documents a program that estimates fish population sizes and annual production rates in small streams from multiple-pass sampling data. A maximum weighted likelihood method is used to estimate population sizes (Carle and Strub, 1978), and a size-frequency method is used to estimate production (Garman and Waters, 1983). The program performs the following steps: (1) reads in the data and performs error checking; (2) where required, uses length-weight regression to fill in missing weights; (3) assigns length classes to the fish; (4) for each date, species, and length class, estimates the population size and its variance; (5) for each date and species, estimates the total population size and its variance; and (6) for each species, estimates the annual production rate and its variance between sampling dates selected by the user. If data from only date are used, only populations are estimated. 9 refs.

  13. Using flowering and heat-loss models for improving greenhouse energy-use efficiency in annual bedding plant production

    USDA-ARS?s Scientific Manuscript database

    In temperate climates, annual bedding plants are typically produced in heated greenhouses from late winter through early summer. Temperature, photoperiod, light intensity, and transplant date are commonly manipulated during commercial production so that plants are in flower for predetermined market ...

  14. Regulation of polyamine synthesis in plants. Annual progress report

    SciTech Connect

    Malmberg, R.L.

    1993-02-09

    Polyamines are small positively charged compounds that have been hypothesized to be involved in a wide variety of plant physiological and development functions. The regulation of the polyamine synthesis pathway is uniquely interesting because of the existence of two pathways to putrescine synthesis, and the consequent questions of how these two pathways are compartmentalized and how they interact with each other. The specific directions our research is taking are: (1) A characterization of arginine decarboxylase regulation; we have discovered two post-translational mechanisms for regulating arginine decarboxylase activity. One of these is a novel protease that clips the arginine decarboxylase pre-protein to activate it. We would like to understand this activating protease better, determine its mechanism of action, and determine its importance in the overall scheme of arginine decarboxylase regulation. (2) We have begun a similar characterization of ornithine decarboxylase by purifying it from plants. (3) We are characterizing the polyamine mutant collection we have developed. (4) Finally, we have begun to characterize the evolution of arginine decarboxylase, as an additional approach that could shed light on its functions in plants. Our intent is to understand arginine decarboxylase structure and regulation in detail, and then to further explore regulatory differences between ornithine and arginine decarboxylases.

  15. Seed zones for maintaining adapted plant populations

    Treesearch

    J. Bradley St. Clair; G. Randy Johnson; Vicky J. Erickson; Richard C. Johnson; Nancy L. Shaw

    2007-01-01

    Seed zones delineate areas within which plant materials can be transferred with little risk that they will be poorly adapted to their new location. They ensure successful restoration and revegetation, and help maintain the integrity of natural genetic structure. The value of seed zones is recognized in numerous policy statements from federal and state agencies. Results...

  16. Optimizing Valencia Planting Patterns and Population Densities

    USDA-ARS?s Scientific Manuscript database

    Currently, most Valencia peanuts are grown in single rows on 36 to 40 inch beds. Because of their bunch-type and erect growth habit, Valencia peanuts do not spread over the whole bed and have the opportunity to benefit from multiple row planting design. This study was conducted near Clovis, NM to ...

  17. Population of North American elk: effects on plant diversity

    Treesearch

    Kelley M. Stewart; R. Terry Bowyer; John G. Kier; Brian L. Dick; Roger W. Ruess

    2009-01-01

    We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported. We documented a positive, linear relationship between plant-species diversity and richness with NAPP. Structural...

  18. Herbivory: effects on plant abundance, distribution and population growth

    PubMed Central

    Maron, John L; Crone, Elizabeth

    2006-01-01

    Plants are attacked by many different consumers. A critical question is how often, and under what conditions, common reductions in growth, fecundity or even survival that occur due to herbivory translate to meaningful impacts on abundance, distribution or dynamics of plant populations. Here, we review population-level studies of the effects of consumers on plant dynamics and evaluate: (i) whether particular consumers have predictably more or less influence on plant abundance, (ii) whether particular plant life-history types are predictably more vulnerable to herbivory at the population level, (iii) whether the strength of plant–consumer interactions shifts predictably across environmental gradients and (iv) the role of consumers in influencing plant distributional limits. Existing studies demonstrate numerous examples of consumers limiting local plant abundance and distribution. We found larger effects of consumers on grassland than woodland forbs, stronger effects of herbivory in areas with high versus low disturbance, but no systematic or unambiguous differences in the impact of consumers based on plant life-history or herbivore feeding mode. However, our ability to evaluate these and other patterns is limited by the small (but growing) number of studies in this area. As an impetus for further study, we review strengths and challenges of population-level studies, such as interpreting net impacts of consumers in the presence of density dependence and seed bank dynamics. PMID:17002942

  19. Do plant population and planting date make a difference in corn production?

    USDA-ARS?s Scientific Manuscript database

    One management practice that can positively or negatively impact corn yield is plant population. Yield potential can also be influenced by the date of planting, which is strongly linked to the at-planting and in-season weather and climatic conditions. Even when considering management changes, we nee...

  20. 1995 Annual epidemiologic surveillance report for Pantex Plant

    SciTech Connect

    1998-06-01

    This report provides a summary of epidemiologic surveillance data collected from the Pantex Plant from January 1, 1995 through December 31,1995. The data were collected by a coordinator at Pantex and submitted to the Epidemiologic Surveillance Data Center,located at Oak Ridge Institute for Science and Education, where quality control procedures and data analyses were carried out. The data presented apply only to Pantex. The main sections of the report are the same as in previous years; the 1995 report provides additional information describing the work force by age and occupational groups.

  1. Dworshak Reservoir Kokanee Population Monitoring, Annual Report 2001.

    SciTech Connect

    Maiolie, Melo; Stark, Eric

    2003-03-01

    Onsite testing of strobe lights was conducted to determine if they repelled kokanee Oncorhynchus nerka away from the turbine intakes at Dworshak Dam. We tested a set of nine strobe lights flashing at a rate of 360 flashes/min placed near the intake of a 90 mW turbine. A split-beam echo sounder was used to determine the effect of strobe light operation on fish density (thought to be mostly kokanee) in front of the turbine intakes. On five nights between December 2001 and January 2002, fish density averaged 110 fish/ha when no lights were flashing. Mean density dropped to 13 fish/ha when the strobe lights were turned on during five additional nights of sampling. This 88% decline in density was significant at the P = 0.009 level of significance based on a paired Student's t test. There appeared to be no tendency for fish to habituate to the lights during the night. Test results indicate that a single set of nine lights may be sufficient to repel kokanee from a turbine intake during the night. We also used split-beam hydroacoustics to monitor the kokanee population in Dworshak Reservoir during 2001. Estimated abundance of kokanee has continued to increase since the spring of 1996 when high entrainment losses occurred. Based on hydroacoustic surveys, we estimated 3,276,000 kokanee in Dworshak Reservoir in early July 2001. This included 2,069,000 age-0 kokanee (90% CI {+-} 16.4%), 801,000 age-1 kokanee (90% CI {+-} 17.8%), and 406,000 age-2 kokanee (90% CI {+-} 20.5%). Entrainment sampling was also conducted with split-beam hydroacoustics a minimum of one continuous 24 h period per month. The highest entrainment rates occurred at night with lower discharges and shallower intake depths. Fish movement patterns suggested that they swam 'at will' in front of the intakes and may have chosen to move into the turbine intakes. Based on monthly hydroacoustic sampling in the forebay, we found that kokanee density was low in July and August during a period of high discharge

  2. LIVESTOCK ACTIVITY AND CHIHUAHUAN DESERT ANNUAL-PLANT COMMUNITIES: BOUNDARY ANALYSIS OF DISTURBANCE GRADIENTS

    EPA Science Inventory

    The impact of domestic livestock on soil properties and perennial vegetation is greatest close to water points and generally decreases exponentially with distance from water. We hypothesized that the impact of livestock on annual-plant communities would be similar to that on per...

  3. Are early summer wildfires an opportunity to revegetate exotic annual grass-invaded plant communities?

    USDA-ARS?s Scientific Manuscript database

    Medusahead (Taeniatherum caput-medusae (L.) Nevski) is an exotic annual grass reducing biodiversity and altering ecosystem function and processes in rangelands. Revegetation of medusahead-invaded plant communities is needed to improve ecosystem function, increase livestock forage production, and im...

  4. Use of Words and Visuals in Modelling Context of Annual Plant

    ERIC Educational Resources Information Center

    Park, Jungeun; DiNapoli, Joseph; Mixell, Robert A.; Flores, Alfinio

    2017-01-01

    This study looks at the various verbal and non-verbal representations used in a process of modelling the number of annual plants over time. Analysis focuses on how various representations such as words, diagrams, letters and mathematical equations evolve in the mathematization process of the modelling context. Our results show that (1) visual…

  5. LIVESTOCK ACTIVITY AND CHIHUAHUAN DESERT ANNUAL-PLANT COMMUNITIES: BOUNDARY ANALYSIS OF DISTURBANCE GRADIENTS

    EPA Science Inventory

    The impact of domestic livestock on soil properties and perennial vegetation is greatest close to water points and generally decreases exponentially with distance from water. We hypothesized that the impact of livestock on annual-plant communities would be similar to that on per...

  6. Do transgenic plants affect rhizobacteria populations?

    PubMed Central

    Filion, Martin

    2008-01-01

    Summary Plant genetic manipulation has led to the development of genetically modified plants (GMPs) expressing various traits. Since their first commercial use in 1996, GMPs have been increasingly used, reaching a global cultivating production area of 114.3 million hectares in 2007. The rapid development of agricultural biotechnology and release of GMPs have provided many agronomic and economic benefits, but has also raised concerns over the potential impact these plants might have on the environment. Among these environmental concerns, the unintentional impact that GMPs might have on soil‐associated microbes, especially rhizosphere‐inhabiting bacteria or rhizobacteria, represents one of the least studied and understood areas. As rhizobacteria are responsible for numerous key functions including nutrient cycling and decomposition, they have been defined as good indicator organisms to assess the general impact that GMPs might have on the soil environment. This minireview summarizes the results of various experiments that have been conducted to date on the impact of GMPs on rhizobacteria. Both biological and technical parameters are discussed and an attempt is made to determine if specific rhizobacterial responses exist for the different categories of GMPs developed to date. PMID:21261867

  7. Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert

    USGS Publications Warehouse

    Brooks, Matthew L.

    2003-01-01

    1. Deserts are one of the least invaded ecosystems by plants, possibly due to naturally low levels of soil nitrogen. Increased levels of soil nitrogen caused by atmospheric nitrogen deposition may increase the dominance of invasive alien plants and decrease the diversity of plant communities in desert regions, as it has in other ecosystems. Deserts should be particularly susceptible to even small increases in soil nitrogen levels because the ratio of increased nitrogen to plant biomass is higher compared with most other ecosystems.2. The hypothesis that increased soil nitrogen will lead to increased dominance by alien plants and decreased plant species diversity was tested in field experiments using nitrogen additions at three sites in the in the Mojave Desert of western North America.3. Responses of alien and native annual plants to soil nitrogen additions were measured in terms of density, biomass and species richness. Effects of nitrogen additions were evaluated during 2 years of contrasting rainfall and annual plant productivity. The rate of nitrogen addition was similar to published rates of atmospheric nitrogen deposition in urban areas adjacent to the Mojave Desert (3·2 g N m−2 year−1). The dominant alien species included the grasses Bromus madritensis ssp. rubens and Schismus spp. (S. arabicus and S. barbatus) and the forb Erodium cicutarium.4. Soil nitrogen addition increased the density and biomass of alien annual plants during both years, but decreased density, biomass and species richness of native species only during the year of highest annual plant productivity. The negative response of natives may have been due to increased competitive stress for soil water and other nutrients caused by the increased productivity of aliens.5. The effects of nitrogen additions were significant at both ends of a natural nutrient gradient, beneath creosote bush Larrea tridentata canopies and in the interspaces between them, although responses varied among

  8. Annual harvests of Corbicula populations prevent clogging of nuclear reactor heat exchangers

    SciTech Connect

    Harvey, R.S.

    1983-01-01

    An annual program for removal of millions of Corbicula from upstream cooling water basins has prevented reclogging of nuclear reactor heat exchanger distributor plates at the Savannah River Plant during the past seven years. There are nine 32-megaliter basins in the three operating reactor areas where some settling of particulates occurs before cooling water is passed through screens in route to heat exchangers. Annual cleanings keep silt/clam substrate levels low and clam sizes small. Data are presented on the size/age distribution for clams recolonizing basins between cleanings.

  9. Non-Native Plant Litter Enhances Soil Carbon Dioxide Emissions in an Invaded Annual Grassland

    PubMed Central

    Zhang, Ling; Wang, Hong; Zou, Jianwen; Rogers, William E.; Siemann, Evan

    2014-01-01

    Litter decomposition is a fundamental ecosystem process in which breakdown and decay of plant detritus releases carbon and nutrients. Invasive exotic plants may produce litter that differs from native plant litter in quality and quantity. Such differences may impact litter decomposition and soil respiration in ways that depend on whether exotic and native plant litters decompose in mixtures. However, few field experiments have examined how exotic plants affect soil respiration via litter decomposition. Here, we conducted an in situ study of litter decomposition of an annual native grass (Eragrostis pilosa), a perennial exotic forb (Alternanthera philoxeroides), and their mixtures in an annual grassland in China to examine potential invasion effects on soil respiration. Alternanthera litter decomposed faster than Eragrostis litter when each was incubated separately. Mass loss in litter mixes was more rapid than predicted from rates in single species bags (only 35% of predicted mass remained at 8 months) showing synergistic effects. Notably, exotic plant litter decomposition rate was unchanged but native plant litter decomposition rate was accelerated in mixtures (decay constant k = 0.20 month−1) compared to in isolation (k = 0.10 month−1). On average, every litter type increased soil respiration compared to bare soil from which litter was removed. However, the increases were larger for mixed litter (1.82 times) than for Alternanthera litter (1.58 times) or Eragrostis litter (1.30 times). Carbon released as CO2 relative to litter carbon input was also higher for mixed litter (3.34) than for Alternathera litter (2.29) or Eragrostis litter (1.19). Our results indicated that exotic Alternanthera produces rapidly decomposing litter which also accelerates the decomposition of native plant litter in litter mixtures and enhances soil respiration rates. Thus, this exotic invasive plant species will likely accelerate carbon cycling and increase soil respiration

  10. Non-native plant litter enhances soil carbon dioxide emissions in an invaded annual grassland.

    PubMed

    Zhang, Ling; Wang, Hong; Zou, Jianwen; Rogers, William E; Siemann, Evan

    2014-01-01

    Litter decomposition is a fundamental ecosystem process in which breakdown and decay of plant detritus releases carbon and nutrients. Invasive exotic plants may produce litter that differs from native plant litter in quality and quantity. Such differences may impact litter decomposition and soil respiration in ways that depend on whether exotic and native plant litters decompose in mixtures. However, few field experiments have examined how exotic plants affect soil respiration via litter decomposition. Here, we conducted an in situ study of litter decomposition of an annual native grass (Eragrostis pilosa), a perennial exotic forb (Alternanthera philoxeroides), and their mixtures in an annual grassland in China to examine potential invasion effects on soil respiration. Alternanthera litter decomposed faster than Eragrostis litter when each was incubated separately. Mass loss in litter mixes was more rapid than predicted from rates in single species bags (only 35% of predicted mass remained at 8 months) showing synergistic effects. Notably, exotic plant litter decomposition rate was unchanged but native plant litter decomposition rate was accelerated in mixtures (decay constant k = 0.20 month(-1)) compared to in isolation (k = 0.10 month(-1)). On average, every litter type increased soil respiration compared to bare soil from which litter was removed. However, the increases were larger for mixed litter (1.82 times) than for Alternanthera litter (1.58 times) or Eragrostis litter (1.30 times). Carbon released as CO2 relative to litter carbon input was also higher for mixed litter (3.34) than for Alternathera litter (2.29) or Eragrostis litter (1.19). Our results indicated that exotic Alternanthera produces rapidly decomposing litter which also accelerates the decomposition of native plant litter in litter mixtures and enhances soil respiration rates. Thus, this exotic invasive plant species will likely accelerate carbon cycling and increase soil respiration

  11. Paducah Gaseous Diffusion Plant Annual Site Environmental Report for 1993

    SciTech Connect

    Not Available

    1994-10-01

    The purpose of this document is to summarize effluent monitoring and environmental surveillance results and compliance with environmental laws, regulations, and orders at the Paducah Gaseous Diffusion Plant (PGDP). Environmental monitoring at PGDP consists of two major activities: effluent monitoring and environmental surveillance. Effluent monitoring is direct measurement or the collection and analysis of samples of liquid and gaseous discharges to the environment. Environmental surveillance is direct measurement or the collection and analysis of samples of air, water, soil, foodstuff, biota, and other media. Environmental monitoring is performed to characterize and quantify contaminants, assess radiation exposures of members of the public, demonstrate compliance with applicable standards and permit requirements, and detect and assess the effects (if any) on the local environment. Multiple samples are collected throughout the year and are analyzed for radioactivity, chemical content, and various physical attributes.

  12. Soil moisture and fungi affect seed survival in California grassland annual plants.

    PubMed

    Mordecai, Erin A

    2012-01-01

    Survival of seeds in the seed bank is important for the population dynamics of many plant species, yet the environmental factors that control seed survival at a landscape level remain poorly understood. These factors may include soil moisture, vegetation cover, soil type, and soil pathogens. Because many soil fungi respond to moisture and host species, fungi may mediate environmental drivers of seed survival. Here, I measure patterns of seed survival in California annual grassland plants across 15 species in three experiments. First, I surveyed seed survival for eight species at 18 grasslands and coastal sage scrub sites ranging across coastal and inland Santa Barbara County, California. Species differed in seed survival, and soil moisture and geographic location had the strongest influence on survival. Grasslands had higher survival than coastal sage scrub sites for some species. Second, I used a fungicide addition and exotic grass thatch removal experiment in the field to tease apart the relative impact of fungi, thatch, and their interaction in an invaded grassland. Seed survival was lower in the winter (wet season) than in the summer (dry season), but fungicide improved winter survival. Seed survival varied between species but did not depend on thatch. Third, I manipulated water and fungicide in the laboratory to directly examine the relationship between water, fungi, and survival. Seed survival declined from dry to single watered to continuously watered treatments. Fungicide slightly improved seed survival when seeds were watered once but not continually. Together, these experiments demonstrate an important role of soil moisture, potentially mediated by fungal pathogens, in driving seed survival.

  13. Soil Moisture and Fungi Affect Seed Survival in California Grassland Annual Plants

    PubMed Central

    Mordecai, Erin A.

    2012-01-01

    Survival of seeds in the seed bank is important for the population dynamics of many plant species, yet the environmental factors that control seed survival at a landscape level remain poorly understood. These factors may include soil moisture, vegetation cover, soil type, and soil pathogens. Because many soil fungi respond to moisture and host species, fungi may mediate environmental drivers of seed survival. Here, I measure patterns of seed survival in California annual grassland plants across 15 species in three experiments. First, I surveyed seed survival for eight species at 18 grasslands and coastal sage scrub sites ranging across coastal and inland Santa Barbara County, California. Species differed in seed survival, and soil moisture and geographic location had the strongest influence on survival. Grasslands had higher survival than coastal sage scrub sites for some species. Second, I used a fungicide addition and exotic grass thatch removal experiment in the field to tease apart the relative impact of fungi, thatch, and their interaction in an invaded grassland. Seed survival was lower in the winter (wet season) than in the summer (dry season), but fungicide improved winter survival. Seed survival varied between species but did not depend on thatch. Third, I manipulated water and fungicide in the laboratory to directly examine the relationship between water, fungi, and survival. Seed survival declined from dry to single watered to continuously watered treatments. Fungicide slightly improved seed survival when seeds were watered once but not continually. Together, these experiments demonstrate an important role of soil moisture, potentially mediated by fungal pathogens, in driving seed survival. PMID:22720037

  14. A Mechanistic Study of Plant and Microbial Controls over R* for Nitrogen in an Annual Grassland

    PubMed Central

    Levine, Jonathan M.; HilleRisLambers, Janneke

    2014-01-01

    Differences in species' abilities to capture resources can drive competitive hierarchies, successional dynamics, community diversity, and invasions. To investigate mechanisms of resource competition within a nitrogen (N) limited California grassland community, we established a manipulative experiment using an R* framework. R* theory holds that better competitors within a N limited community should better depress available N in monoculture plots and obtain higher abundance in mixture plots. We asked whether (1) plant uptake or (2) plant species influences on microbial dynamics were the primary drivers of available soil N levels in this system where N structures plant communities. To disentangle the relative roles of plant uptake and microbially-mediated processes in resource competition, we quantified soil N dynamics as well as N pools in plant and microbial biomass in monoculture plots of 11 native or exotic annual grassland plants over one growing season. We found a negative correlation between plant N content and soil dissolved inorganic nitrogen (DIN, our measure of R*), suggesting that plant uptake drives R*. In contrast, we found no relationship between microbial biomass N or potential net N mineralization and DIN. We conclude that while plant-microbial interactions may have altered the overall quantity of N that plants take up, the relationship between species' abundance and available N in monoculture was largely driven by plant N uptake in this first year of growth. PMID:25170943

  15. A mechanistic study of plant and microbial controls over R* for nitrogen in an annual grassland.

    PubMed

    Yelenik, Stephanie G; Colman, Benjamin P; Levine, Jonathan M; HilleRisLambers, Janneke

    2014-01-01

    Differences in species' abilities to capture resources can drive competitive hierarchies, successional dynamics, community diversity, and invasions. To investigate mechanisms of resource competition within a nitrogen (N) limited California grassland community, we established a manipulative experiment using an R* framework. R* theory holds that better competitors within a N limited community should better depress available N in monoculture plots and obtain higher abundance in mixture plots. We asked whether (1) plant uptake or (2) plant species influences on microbial dynamics were the primary drivers of available soil N levels in this system where N structures plant communities. To disentangle the relative roles of plant uptake and microbially-mediated processes in resource competition, we quantified soil N dynamics as well as N pools in plant and microbial biomass in monoculture plots of 11 native or exotic annual grassland plants over one growing season. We found a negative correlation between plant N content and soil dissolved inorganic nitrogen (DIN, our measure of R*), suggesting that plant uptake drives R*. In contrast, we found no relationship between microbial biomass N or potential net N mineralization and DIN. We conclude that while plant-microbial interactions may have altered the overall quantity of N that plants take up, the relationship between species' abundance and available N in monoculture was largely driven by plant N uptake in this first year of growth.

  16. (Restriction of virus infection by plants: Annual report, 1986)

    SciTech Connect

    Bruening, G.

    1986-12-05

    This research concerns the strong resistance, or even immunity, against a specific virus that is exhibited by one or a few lines of a plant species, in contrast to the general susceptibility of most lines of that species. The contrast between the reactions to virus inoculation of different lines of one species implies that a single gene or a very few genes may mediate the resistance or immunity. The prospects for isolating, studying and transferring such a gene should be good for a system with these characteristics. Seedlings of a line Arlington of the cowpea (Vigna unguiculata) fail to support the replication of cowpea mosaic virus strain SB (CPMV-SB). Genetic crosses of Arlington cowpea to the systemic host Blackeye 5 cowpea show that the immunity is inherited as a simple dominant gene. In contrast to the seedlings, the protoplasts of the Arlington cowpea support CPMV-SB replication, but only to a very low level compared to protoplasts of Blackeye 5 cowpeas. From evidence reported earlier we concluded that Arlington cowpea protoplasts restrict the production of CPMV-SB proteins. We postulated, and obtained evidence for, a proteinase inhibitor that is specific for a CPMV-SB proteinase. This proteinase inhibitor is our prime candidate for the mediator of the resistance of Arlington protoplasts to CPMV-SB. Progress to date is described.

  17. [Restriction of virus infection by plants: Annual report, 1986

    SciTech Connect

    Bruening, G.

    1986-12-05

    This research concerns the strong resistance, or even immunity, against a specific virus that is exhibited by one or a few lines of a plant species, in contrast to the general susceptibility of most lines of that species. The contrast between the reactions to virus inoculation of different lines of one species implies that a single gene or a very few genes may mediate the resistance or immunity. The prospects for isolating, studying and transferring such a gene should be good for a system with these characteristics. Seedlings of a line Arlington of the cowpea (Vigna unguiculata) fail to support the replication of cowpea mosaic virus strain SB (CPMV-SB). Genetic crosses of Arlington cowpea to the systemic host Blackeye 5 cowpea show that the immunity is inherited as a simple dominant gene. In contrast to the seedlings, the protoplasts of the Arlington cowpea support CPMV-SB replication, but only to a very low level compared to protoplasts of Blackeye 5 cowpeas. From evidence reported earlier we concluded that Arlington cowpea protoplasts restrict the production of CPMV-SB proteins. We postulated, and obtained evidence for, a proteinase inhibitor that is specific for a CPMV-SB proteinase. This proteinase inhibitor is our prime candidate for the mediator of the resistance of Arlington protoplasts to CPMV-SB. Progress to date is described.

  18. Annual Energy Production (AEP) optimization for tidal power plants based on Evolutionary Algorithms - Swansea Bay Tidal Power Plant AEP optimization

    NASA Astrophysics Data System (ADS)

    Kontoleontos, E.; Weissenberger, S.

    2016-11-01

    In order to be able to predict the maximum Annual Energy Production (AEP) for tidal power plants, an advanced AEP optimization procedure is required for solving the optimization problem which consists of a high number of design variables and constraints. This efficient AEP optimization procedure requires an advanced optimization tool (EASY software) and an AEP calculation tool that can simulate all different operating modes of the units (bidirectional turbine, pump and sluicing mode). The EASY optimization software is a metamodel-assisted Evolutionary Algorithm (MAEA) that can be used in both single- and multi-objective optimization problems. The AEP calculation tool, developed by ANDRITZ HYDRO, in combination with EASY is used to maximize the tidal annual energy produced by optimizing the plant operation throughout the year. For the Swansea Bay Tidal Power Plant project, the AEP optimization along with the hydraulic design optimization and the model testing was used to evaluate all different hydraulic and operating concepts and define the optimal concept that led to a significant increase of the AEP value. This new concept of a triple regulated “bi-directional bulb pump turbine” for Swansea Bay Tidal Power Plant (16 units, nominal power above 320 MW) along with its AEP optimization scheme will be presented in detail in the paper. Furthermore, the use of an online AEP optimization during operation of the power plant, that will provide the optimal operating points to the control system, will be also presented.

  19. Annual ryegrass-associated bacteria with potential for plant growth promotion.

    PubMed

    Castanheira, Nádia; Dourado, Ana Catarina; Alves, Paula Isabel; Cortés-Pallero, Alícia Maria; Delgado-Rodríguez, Ana Isabel; Prazeres, Ângela; Borges, Nuno; Sánchez, Claudia; Barreto Crespo, Maria Teresa; Fareleira, Paula

    2014-01-01

    Annual ryegrass is a fast-growing cool-season grass broadly present in the Portuguese "montado", a typically Mediterranean agro-forestry-pastoral ecosystem. A culture-dependent approach was used to investigate natural associations of this crop with potentially beneficial bacteria, aiming to identify strains suitable for biofertilization purposes. Annual ryegrass seedlings were used to trap bacteria from three different soils in laboratory conditions. Using a nitrogen-free microaerophilic medium, 147 isolates were recovered from the rhizosphere, rhizoplane, and surface-sterilized plant tissues, which were assigned to 12 genera in classes Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacilli and Actinobacteria. All isolates were able to grow in the absence of nitrogen and several of them were able to perform in vitro activities related to plant growth promotion. Isolates of the genera Sphingomonas and Achromobacter were found to be the most effective stimulators of annual ryegrass growth under nitrogen limitation (47-92% biomass increases). Major enhancements were obtained with isolates G3Dc4 (Achromobacter sp.) and G2Ac10 (Sphingomonas sp.). The latest isolate was also able to increment plant growth in nitrogen-supplemented medium, as well as the phosphate solubilizer and siderophore producer, G1Dc10 (Pseudomonas sp.), and the cellulose/pectin hydrolyser, G3Ac9 (Paenibacillus sp.). This study represents the first survey of annual ryegrass-associated bacteria in the "montado" ecosystem and unveiled a set of strains with potential for use as inoculants.

  20. Genome-wide investigation reveals high evolutionary rates in annual model plants

    PubMed Central

    2010-01-01

    Background Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials. Results According to the cross-comparisons among the four species, 74-82% of the nuclear genes and 71-97% of the chloroplast genes suggested higher rates of molecular evolution in the two annuals than those in the two perennials. The significant heterogeneity in evolutionary rate between annuals and perennials was consistently found both in nonsynonymous sites and synonymous sites. While a linear correlation of evolutionary rates in orthologous genes between species was observed in nonsynonymous sites, the correlation was weak or invisible in synonymous sites. This tendency was clearer in nuclear genes than in chloroplast genes, in which the overall evolutionary rate was small. The slope of the regression line was consistently lower than unity, further confirming the higher evolutionary rate in annuals at the genomic level. Conclusions The higher evolutionary rate in annuals than in perennials appears to be a universal phenomenon both in nuclear and chloroplast genomes in the four dicot model plants we investigated. Therefore, such heterogeneity in evolutionary rate should result from factors that have genome

  1. Age-specific survival and annual variation in survival of female chamois differ between populations.

    PubMed

    Bleu, Josefa; Herfindal, Ivar; Loison, Anne; Kwak, Anne M G; Garel, Mathieu; Toïgo, Carole; Rempfler, Thomas; Filli, Flurin; Sæther, Bernt-Erik

    2015-12-01

    In many species, population dynamics are shaped by age-structured demographic parameters, such as survival, which can cause age-specific sensitivity to environmental conditions. Accordingly, we can expect populations with different age-specific survival to be differently affected by environmental variation. However, this hypothesis is rarely tested at the intra-specific level. Using capture-mark-recapture models, we quantified age-specific survival and the extent of annual variations in survival of females of alpine chamois in two sites. In one population, survival was very high (>0.94; Bauges, France) until the onset of senescence at approximately 7 years old, whereas the two other populations (Swiss National Park, SNP) had a later onset (12 years old) and a lower rate of senescence. Senescence patterns are therefore not fixed within species. Annual variation in survival was higher in the Bauges (SD = 0.26) compared to the SNP populations (SD = 0.20). Also, in each population, the age classes with the lowest survival also experienced the largest temporal variation, in accordance with inter-specific comparisons showing a greater impact of environmental variation on these age classes. The large difference between the populations in age-specific survival and variation suggests that environmental variation and climate change will affect these populations differently.

  2. European annual cosmic-ray dose map and estimation of population exposure

    NASA Astrophysics Data System (ADS)

    Cinelli, Giorgia; Gruber, Valeria; De Felice, Luca; Bossew, Peter; Hernández-Ceballos, Miguel Angel; Tollefsen, Tore; Mundigl, Stefan; De Cort, Marc

    2017-04-01

    The Earth is continually bombarded by high energy cosmic-ray particles and the worldwide average exposure to cosmic rays represents about 13% of the total annual effective dose received by the population. Therefore assessment of cosmic-ray exposure at ground level is of great interest to better understand population exposure to ionizing radiation. In the present work the annual effective dose resulting from cosmic radiation (photons, direct ionizing and neutron components) at ground level has been calculated following a simple methodology based only on elevation data. The European annual cosmic-ray dose map, at 1 km resolution, is presented and described. It reports the annual effective dose that a person may receive from cosmic rays at ground level, and it ranges from about 300 to 4000 microSv. The spatial distribution of the cosmic-ray dose rate over Europe obviously reflects the elevation map. The map shows that for half of the considered territory the annual cosmic-ray dose is below 360 microSv and for less than 1% above 1000 μmicroSv. The highest values are obtained at the highest places of Europe, such as the Alps, the Pyrenees and in eastern Turkey (with mountains above 3000 masl), in the latter reaching the maximum value of 4000 microSv. On the contrary, the minimum value of 300 microSv at sea level coincides mainly with coastal locations. The map is part of the European Atlas of Natural Radiation, and it will be useful to estimate the annual dose that the public may receive from natural radioactivity. Moreover, thanks to the availability of population data, the annual cosmic-ray collective dose has been evaluated and population-weighted average annual effective dose (per capita) due to cosmic ray has been estimated for each European country considered. The values range from about 300 microSv (Iceland) to 400 microSv (Turkey) per capita. The average value for all the countries considered is 330 microSv per capita. This work represents a starting point in

  3. Effects of an invasive plant on population dynamics in toads.

    PubMed

    Greenberg, Daniel A; Green, David M

    2013-10-01

    When populations decline in response to unfavorable environmental change, the dynamics of their population growth shift. In populations that normally exhibit high levels of variation in recruitment and abundance, as do many amphibians, declines may be difficult to identify from natural fluctuations in abundance. However, the onset of declines may be evident from changes in population growth rate in sufficiently long time series of population data. With data from 23 years of study of a population of Fowler's toad (Anaxyrus [ = Bufo] fowleri) at Long Point, Ontario (1989-2011), we sought to identify such a shift in dynamics. We tested for trends in abundance to detect a change point in population dynamics and then tested among competing population models to identify associated intrinsic and extrinsic factors. The most informative models of population growth included terms for toad abundance and the extent of an invasive marsh plant, the common reed (Phragmites australis), throughout the toads' marshland breeding areas. Our results showed density-dependent growth in the toad population from 1989 through 2002. After 2002, however, we found progressive population decline in the toads associated with the spread of common reeds and consequent loss of toad breeding habitat. This resulted in reduced recruitment and population growth despite the lack of significant loss of adult habitat. Our results underscore the value of using long-term time series to identify shifts in population dynamics coincident with the advent of population decline. © 2013 Society for Conservation Biology.

  4. Plant community diversity and native plant abundance decline with increasing abundance of an exotic annual grass

    USDA-ARS?s Scientific Manuscript database

    Exotic plants are generally considered a serious problem in wildlands around the globe. However, some argue that the impacts of exotic plants have been exaggerated and that biodiversity and other important plant community characteristics are commonly improved with invasion. Thus, disagreement exis...

  5. Annual Glyphosate Treatments Alter Growth of Unaffected Bentgrass (Agrostis) Weeds and Plant Community Composition

    PubMed Central

    Ahrens, Collin W.; Auer, Carol A.

    2012-01-01

    Herbicide resistance is becoming more common in weed ecotypes and crop species including turfgrasses, but current gaps in knowledge limit predictive ecological risk assessments and risk management plans. This project examined the effect of annual glyphosate applications on the vegetative growth and reproductive potential of two weedy bentgrasses, creeping bentgrass (CB) and redtop (RT), where the glyphosate resistance (GR) trait was mimicked by covering the bentgrass plants during glyphosate application. Five field plots were studied in habitats commonly inhabited by weedy bentgrasses including an agricultural hayfield, natural meadow, and wasteland. Results showed that annual glyphosate treatment improved bentgrass survivorship, vegetative growth, and reproductive potential compared with bentgrass in unsprayed subplots. In the second year of growth, RT plants had an 86-fold increase in flower number in glyphosate-treated subplots versus controls, while CB plants had a 20-fold increase. At the end of the three year study, plant community composition had changed in glyphosate-treated subplots in hayfield and meadow plots compared to controls. Soils in subplots receiving glyphosate had higher nitrate concentrations than controls. This is the first study to mimic the GR trait in bentgrass plants with the goal of quantifying bentgrass response to glyphosate selection pressure and understanding the impacts on surrounding plant communities. PMID:23226530

  6. Colonization and beneficial effects on annual ryegrass by mixed inoculation with plant growth promoting bacteria.

    PubMed

    Castanheira, Nádia L; Dourado, Ana Catarina; Pais, Isabel; Semedo, José; Scotti-Campos, Paula; Borges, Nuno; Carvalho, Gilda; Barreto Crespo, Maria Teresa; Fareleira, Paula

    2017-05-01

    Multi-strain inoculants have increased potential to accomplish a diversity of plant needs, mainly attributed to its multi-functionality. This work evaluated the ability of a mixture of three bacteria to colonize and induce a beneficial response on the pasture crop annual ryegrass. Pseudomonas G1Dc10 and Paenibacillus G3Ac9 were previously isolated from annual ryegrass and were selected for their ability to perform multiple functions related to plant growth promotion. Sphingomonas azotifigens DSMZ 18530(T) was included due to nitrogen fixing ability. The effects of the bacterial mixture were assessed in gnotobiotic plant inoculation assays and compared with single and dual inoculation treatments. Triple inoculation with 3×10(8) bacteria significantly increased plant dry weight and leaf pigments, indicating improved photosynthetic performance. Plant lipid biosynthesis was enhanced by 65%, mainly due to the rise of linolenic acid, an omega-3 fatty acid with high dietary value. Electrolyte leakage, an indicator of plant membrane stability under stress, was decreased pointing to a beneficial effect by inoculation. Plants physiological condition was more favoured by triple inoculation than by single, although benefits on biomass were only evident relative to non-inoculated plants. The colonization behaviour and coexistence in plant tissues were assessed using FISH and GFP-labelling, combined with confocal microscopy and a cultivation-based approach for quantification. The three strains occupied the same sites, localizing preferentially along root hairs and in stem epidermis. Endophytic colonization was observed as bacteria entered root and stem inner tissues. This study reveals the potential of this mixture of strains for biofertilization, contributing to improve crop productivity and nutritional value.

  7. Optimal allocation in annual plants and its implications for drought response

    NASA Astrophysics Data System (ADS)

    Caldararu, Silvia; Smith, Matthew; Purves, Drew

    2015-04-01

    The concept of plant optimality refers to the plastic behaviour of plants that results in lifetime and offspring fitness. Optimality concepts have been used in vegetation models for a variety of processes, including stomatal conductance, leaf phenology and biomass allocation. Including optimality in vegetation models has the advantages of creating process based models with a relatively low complexity in terms of parameter numbers but which are capable of reproducing complex plant behaviour. We present a general model of plant growth for annual plants based on the hypothesis that plants allocate biomass to aboveground and belowground vegetative organs in order to maintain an optimal C:N ratio. The model also represents reproductive growth through a second optimality criteria, which states that plants flower when they reach peak nitrogen uptake. We apply this model to wheat and maize crops at 15 locations corresponding to FLUXNET cropland sites. The model parameters are data constrained using a Bayesian fitting algorithm to eddy covariance data, satellite derived vegetation indices, specifically the MODIS fAPAR product and field level crop yield data. We use the model to simulate the plant drought response under the assumption of plant optimality and show that the plants maintain unstressed total biomass levels under drought for a reduction in precipitation of up to 40%. Beyond that level plant response stops being plastic and growth decreases sharply. This behaviour results simply from the optimal allocation criteria as the model includes no explicit drought sensitivity component. Models that use plant optimality concepts are a useful tool for simulation plant response to stress without the addition of artificial thresholds and parameters.

  8. Complex Consequences of Herbivory and Interplant Cues in Three Annual Plants

    PubMed Central

    Pearse, Ian S.; Porensky, Lauren M.; Yang, Louie H.; Stanton, Maureen L.; Karban, Richard; Bhattacharyya, Lisa; Cox, Rosa; Dove, Karin; Higgins, August; Kamoroff, Corrina; Kirk, Travis; Knight, Christopher; Koch, Rebecca; Parker, Corwin; Rollins, Hilary; Tanner, Kelsey

    2012-01-01

    Information exchange (or signaling) between plants following herbivore damage has recently been shown to affect plant responses to herbivory in relatively simple natural systems. In a large, manipulative field study using three annual plant species (Achyrachaena mollis, Lupinus nanus, and Sinapis arvensis), we tested whether experimental damage to a neighboring conspecific affected a plant's lifetime fitness and interactions with herbivores. By manipulating relatedness between plants, we assessed whether genetic relatedness of neighboring individuals influenced the outcome of having a damaged neighbor. Additionally, in laboratory feeding assays, we assessed whether damage to a neighboring plant specifically affected palatability to a generalist herbivore and, for S. arvensis, a specialist herbivore. Our study suggested a high level of contingency in the outcomes of plant signaling. For example, in the field, damaging a neighbor resulted in greater herbivory to A. mollis, but only when the damaged neighbor was a close relative. Similarly, in laboratory trials, the palatability of S. arvensis to a generalist herbivore increased after the plant was exposed to a damaged neighbor, while palatability to a specialist herbivore decreased. Across all species, damage to a neighbor resulted in decreased lifetime fitness, but only if neighbors were closely related. These results suggest that the outcomes of plant signaling within multi-species neighborhoods may be far more context-specific than has been previously shown. In particular, our study shows that herbivore interactions and signaling between plants are contingent on the genetic relationship between neighboring plants. Many factors affect the outcomes of plant signaling, and studies that clarify these factors will be necessary in order to assess the role of plant information exchange about herbivory in natural systems. PMID:22675439

  9. Population density of North American elk: effects on plant diversity.

    PubMed

    Stewart, Kelley M; Bowyer, R Terry; Kie, John G; Dick, Brian L; Ruess, Roger W

    2009-08-01

    Large, herbivorous mammals have profound effects on ecosystem structure and function and often act as keystone species in ecosystems they inhabit. Density-dependent processes associated with population structure of large mammals may interact with ecosystem functioning to increase or decrease biodiversity, depending on the relationship of herbivore populations relative to the carrying capacity (K) of the ecosystem. We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported. We documented a positive, linear relationship between plant-species diversity and richness with NAPP. Structural equation modeling revealed significant indirect relationships between population density of herbivores, NAPP, and species diversity. We observed an indirect effect of density-dependent processes in large, herbivorous mammals and species diversity of plants through changes in NAPP in this montane ecosystem. Changes in species diversity of plants in response to herbivory may be more indirect in ecosystems with long histories of herbivory. Those subtle or indirect effects of herbivory may have strong effects on ecosystem functioning, but may be overlooked in plant communities that are relatively resilient to herbivory.

  10. Urban plants as genetic reservoirs or threats to the integrity of bushland plant populations.

    PubMed

    Roberts, David G; Ayre, David J; Whelan, Robert J

    2007-06-01

    Remnant plants in urban fringes and native plants in gardens have the potential to contribute to the conservation of threatened plants by increasing genetic diversity, effective size of populations, and levels of genetic connectedness. But they also pose a threat through the disruption of locally adapted gene pools. At Hyams Beach, New South Wales, Australia, four bushland stands of the rare shrub, Grevillea macleayana McGillivray, surround an urban area containing remnant and cultivated specimens of this species. Numbers of inflorescences per plant, fruits per plant, and visits by pollinators were similar for plants in urban gardens and bushland. Urban plants represented a substantial but complex genetic resource, displaying more genetic diversity than bushland plants judged byH(e), numbers of alleles per locus, and number of private alleles. Of 27 private alleles in urban plants, 17 occurred in a set of 19 exotic plants. Excluding the exotic plants, all five stands displayed a moderate differentiation (F(ST)= 0.14 +/- 0.02), although the urban remnants clustered with two of the bushland stands. These patterns may be explained by high levels of selfing and inbreeding in this species and by long-distance dispersal (several seeds in the urban stand were fathered by plants in other stands). Genetic leakage (gene flow) from exotic plants to 321 seeds on surrounding remnant or bushland plants has not occurred. Our results demonstrate the conservation value of this group of urban plants, which are viable, productive, genetically diverse, and interconnected with bushland plants. Gene flow has apparently not yet led to genetic contamination of bushland populations, but high levels of inbreeding would make this a rare event and difficult to detect.

  11. Effect of pre-planting irrigation, maize planting pattern and nitrogen on weed seed bank population.

    PubMed

    Hemmati, E; Vazan, S; Oveisi, M

    2011-01-01

    Pre-planting irrigation and planting patterns are important factors in weed management that effect on seed bank. Additionally, the nitrogen is the most important factor in plant growth that affects weed-crop competition and ultimately, seed rain into the soil. A field experiment was conducted to study the effect of nitrogen application rates, pre-planting irrigation and maize planting patterns on weed seed bank population. Experimental factors were nitrogen rates at 4 levels (200, 300, 400 and 500 kg per hectare) as main plot; and pre-planting irrigation at 2 levels (irrigation before planting plus weeding emerged seedlings and, irrigation after sowing), and maize planting patterns (one-row and two-row planting of maize with same density per square of row length) that were assigned in a factorial arrangement to the sub plots. Soil samples were taken at the beginning of the season (before planting of maize) and at the end of the season (after harvest) at depth of 0-5 cm in the fixed quadrates (60 cm x 60 cm). The weed seeds were extracted from the soil samples and were identified using standard methods. The majority of weed seed bank populations included 6 weed species: Portulaca oleracea, Chenopodium album, Amaranthus retroflexus, Sorghum halepense, Daturea stramonium, Xanthium strumarium. Results showed that population of weed seed bank increased significantly with increasing nitrogen rate. The increasing rate was different between one-row and two-row planting patterns. The parameters indicated that seed bank population was much higher in a one row planting pattern of maize. With two-row planting, seed bank was decreased by 34, 26, 20 and 5% at 200, 300, 400 and 500 kg N/ha, respectively. Pre-planting irrigation was also found an effective implement to reduce the weed seed bank. When pre-planting irrigation was applied, seed bank was decreased by 57, 43, 34 and 9% at 200, 300, 400 and 500 kg N/ha. Increasing nitrogen because of weed's better growth and higher seed

  12. Signaling among neighboring plants and the development of size inequalities in plant populations

    SciTech Connect

    Ballare, C.L. |; Scopel, A.L. |; Jordan, E.T.; Vierstra, R.D.

    1994-10-11

    Transgenic tobacco plants that express an oat phytochrome gene (phyA) under control of the cauliflower mosaic virus (CaMV) 35S promoter and display altered photophysiology were used to test the role of light as a vehicle of information in dominance relationships between neighboring plants. Compared with the isogenic wild type, phyA-overexpressing plants showed dramatically reduced morphological responsivity to changes in the red/far red ratio of the incident light and to the proximity of neighboring plants in spacing experiments. In transgenic canopies an increase in stand density caused the small plants of the population to be rapidly suppressed by their neighbors. In wild-type canopies, plants responded to increased density with large morphological changes, and there appeared to be an inverse relationship between the magnitude of this morphological response and the ranking of the individual plant in the population size hierarchy. In these wild-type populations, size inequality increased only moderately with density within the time frame of the experiments. The results suggest that, in crowded stands, the ability of individual plants to acquire information about their light environment via phytochrome plays a central role in driving architectural changes that, at the population level, delay the development of size differences between neighbors.

  13. 2003 Pantex Plant Annual Illness and Injury Surveillance Report, Revised September 2007

    SciTech Connect

    U.S. Department of Energy, Office of Health, Safety and Security, Office of Illness and Injury Prevention Programs

    2007-10-05

    Annual Illness and Injury Surveillance Program report for 2003 for the Pantex Plant. DOE is commited to assuring the health and safety of its workers. This includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. The IISP monitors illnesses and health conditions that result in an absence of workdays, occupational injuries and illnesses, and disabilities and deaths among current workers.

  14. 2003 Kansas City Plant Annual Illness and Injury Surveillance Report, Revised September 2007

    SciTech Connect

    U.S. Department of Energy, Office of Health, Safety and Security, Office of Illness and Injury Prevention Programs

    2007-10-04

    Annual Illness and Injury Surveillance Program report for 2003 for the Kansas City Plant. The U.S. Department of Energy’s (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. The IISP monitors illnesses and health conditions that result in an absence of workdays, occupational injuries and illnesses, and disabilities and deaths among current workers.

  15. Habitat invasibility and dominance by alien annual plants in the western Mojave Desert

    USGS Publications Warehouse

    Brooks, M.L.

    1999-01-01

    Patterns of habitat invasibility and alien dominance, respectively measured as species richness and biomass of alien annual plants, were evaluated in association with four habitat factors at the Desert Tortoise Research Natural Area (DTNA) in the western Mojave Desert, USA. Habitat factors varied in levels of disturbance outside (high) and inside (low) the DTNA, and in levels of soil nutrients in washlet (high) and hummock (low) topographic positions, in Larrea-north (high), Larrea-south (medium), and interspace (low) microhabitats near creosote bushes (Larrea tridentata), and during 1995 when rainfall was 207% (high) and 1994 when rainfall was 52% (low) of the long-term average. Dominant alien plants included the annual grasses Bromus rubens, Bromus trinii, and Schismus spp., and the forb Erodium cicutarium. Species richness and dominance of alien annual plants were slightly higher where disturbance was high, and much higher where soil nutrients were high. B. rubens and B. trinii were most dominant in washlets and in the Larrea-north microhabitats during both years. These two species evolved in mesic ecosystems, and appeared to be particularly limited by soil nutrients at this site. Schismus spp. and E. cicutarium were also most dominant in washlets, but their dominance varied between interspaces in 1994 and the Larrea-south microhabitat in 1995. Monitoring to detect the invasion of new annual plants should focus on regions of high rainfall and nitrogen deposition and on washes and beneath-canopy microhabitats. The ecological range of each alien species should be evaluated separately, because their evolutionary origins may greatly affect their patterns of invasion and dominance in the Mojave Desert.

  16. Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

    NASA Technical Reports Server (NTRS)

    Carneggie, D. M.; Degloria, S. D.; Colwell, R. N.

    1977-01-01

    A network of sampling sites throughout the annual grassland region was established to correlate plant growth in stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. Data were analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site, and changing growth conditions.

  17. Properties of maximum likelihood male fertility estimation in plant populations.

    PubMed Central

    Morgan, M T

    1998-01-01

    Computer simulations are used to evaluate maximum likelihood methods for inferring male fertility in plant populations. The maximum likelihood method can provide substantial power to characterize male fertilities at the population level. Results emphasize, however, the importance of adequate experimental design and evaluation of fertility estimates, as well as limitations to inference (e.g., about the variance in male fertility or the correlation between fertility and phenotypic trait value) that can be reasonably drawn. PMID:9611217

  18. Cotyledon damage affects seed number through final plant size in the annual grassland species Medicago lupulina.

    PubMed

    Zhang, Shiting; Zhao, Chuan; Lamb, Eric G

    2011-03-01

    The effects of cotyledon damage on seedling growth and survival are relatively well established, but little is known about the effects on aspects of plant fitness such as seed number and size. Here the direct and indirect mechanisms linking cotyledon damage and plant fitness in the annual species Medicago lupulina are examined. Growth and reproductive traits, including mature plant size, time to first flowering, flower number, seed number and individual seed mass were monitored in M. lupulina plants when zero, one or two cotyledons were removed at 7 d old. Structural equation modelling (SEM) was used to examine the mechanisms linking cotyledon damage to seed number and seed mass. Cotyledon damage reduced seed number but not individual seed mass. The primary mechanism was a reduction in plant biomass with cotyledon damage that in turn reduced seed number primarily through a reduction in flower numbers. Although cotyledon damage delayed flower initiation, it had little effect on seed number. Individual seed mass was not affected by cotyledon removal, but there was a trade-off between seed number and seed mass. It is shown how a network of indirect mechanisms link damage to cotyledons and fitness in M. lupulina. Cotyledon damage had strong direct effects on both plant size and flowering phenology, but an analysis of the causal relationships among plant traits and fitness components showed that a reduction in plant size associated with cotyledon damage was an important mechanism influencing fitness.

  19. Decreasing annual nest counts in a globally important loggerhead sea turtle population.

    PubMed

    Witherington, Blair; Kubilis, Paul; Brost, Beth; Meylan, Anne

    2009-01-01

    nests over the survey region. We argue that the decline in annual loggerhead nest counts in peninsular Florida can best be explained by a decline in the number of adult female loggerheads in the population. Causes of this decline are explored.

  20. Dynamics of three types of annual plants competing for water and light

    NASA Astrophysics Data System (ADS)

    Pȩkalski, Andrzej; Szwabiński, Janusz

    2013-02-01

    We present and discuss a Monte Carlo model describing the dynamics of three types of annual plants which have different tolerances to shade and drought. External conditions (water and light) fluctuate around some values which are our control parameters and which decide how many resources the system receives. The plants compete with their nearest neighbours for the resources, however not in the same way. We show that for certain ranges of the control parameters a coexistence of the three species is observed. We discuss how the characteristics of the the plants - their number, germination, biomass or the number of nearest neighbours, depend on the two control parameters characterising external conditions. We show that elimination is done at the level of adult plants, not seedlings. We find also cooperative behaviour of plants in difficult conditions, as observed in field studies and we propose an explanation for this fact. Apart from plants tolerating shade but requiring more water and those tolerating drought but needing more light, which are common in nature, we introduce a third species with intermediary demands. We investigate under what conditions this new species could dominate and whether the total number of plants, regardless of their type, is larger with or without the intermediate plant. We show that in our model, like in nature, systems with two kinds of plants with opposite characteristics are, in general, as effective as a system with an additional third type of plants. We show that two contradictory hypotheses made by biologists, concerning the demands of plants in drought and shade, could be both true, however in different regimes.

  1. Livestock grazing supports native plants and songbirds in a California annual grassland.

    PubMed

    Gennet, Sasha; Spotswood, Erica; Hammond, Michele; Bartolome, James W

    2017-01-01

    Over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species-Western Meadowlark (Sturnella neglecta), Horned Lark (Eremophila alpestris), and Grasshopper Sparrow (Ammodramus savannarum)-at sites in central California during breeding season. In California's Mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of native bunchgrass and forbs. Livestock grazing, primarily with beef cattle, is the most widely used management tool. Compared with ungrazed plots, grazed plots had higher bare ground, native plant cover, and vertically heterogeneous vegetation. Grazed plots also had less plant litter and shorter vegetation. Higher native plant cover, which is predominantly composed of bunchgrasses in our study area, was associated with livestock grazing and north-facing aspects. Using an information theoretic approach, we found that all three bird species had positive associations with native plant abundance and neutral (Western Meadowlark, Grasshopper Sparrow) or positive (Horned Lark) association with livestock grazing. All species favored flatter areas. Horned Larks and Western Meadowlark occurred more often where there were patches of bare ground. Western Meadowlarks and Grasshopper Sparrows were most common on north-facing slopes, suggesting that these species may be at risk from projected climate change. These findings demonstrate that livestock grazing is compatible with or supports grassland bird conservation in Mediterranean-type grasslands, including areas with high levels of exotic annual grass invasion, in part because grazing supports the persistence of native plants and heterogeneity in vegetation structure. However, conservation of low-lying grasslands with high native species presence, and active management to increase the abundance of native plant species are also likely to

  2. Livestock grazing supports native plants and songbirds in a California annual grassland

    PubMed Central

    Hammond, Michele; Bartolome, James W.

    2017-01-01

    Over eight years we measured the effects of plant community composition, vegetation structure, and livestock grazing on occurrence of three grassland bird species—Western Meadowlark (Sturnella neglecta), Horned Lark (Eremophila alpestris), and Grasshopper Sparrow (Ammodramus savannarum)—at sites in central California during breeding season. In California’s Mediterranean-type climatic region, coastal and inland grassland vegetation is dominated by exotic annual grasses with occasional patches of native bunchgrass and forbs. Livestock grazing, primarily with beef cattle, is the most widely used management tool. Compared with ungrazed plots, grazed plots had higher bare ground, native plant cover, and vertically heterogeneous vegetation. Grazed plots also had less plant litter and shorter vegetation. Higher native plant cover, which is predominantly composed of bunchgrasses in our study area, was associated with livestock grazing and north-facing aspects. Using an information theoretic approach, we found that all three bird species had positive associations with native plant abundance and neutral (Western Meadowlark, Grasshopper Sparrow) or positive (Horned Lark) association with livestock grazing. All species favored flatter areas. Horned Larks and Western Meadowlark occurred more often where there were patches of bare ground. Western Meadowlarks and Grasshopper Sparrows were most common on north-facing slopes, suggesting that these species may be at risk from projected climate change. These findings demonstrate that livestock grazing is compatible with or supports grassland bird conservation in Mediterranean-type grasslands, including areas with high levels of exotic annual grass invasion, in part because grazing supports the persistence of native plants and heterogeneity in vegetation structure. However, conservation of low-lying grasslands with high native species presence, and active management to increase the abundance of native plant species are also

  3. Effects of elevated CO2 concentration on seed production in C3 annual plants.

    PubMed

    Hikosaka, Kouki; Kinugasa, Toshihiko; Oikawa, Shimpei; Onoda, Yusuke; Hirose, Tadaki

    2011-02-01

    The response of seed production to CO(2) concentration ([CO(2)]) is known to vary considerably among C(3) annual species. Here we analyse the interspecific variation in CO(2) responses of seed production per plant with particular attention to nitrogen use. Provided that seed production is limited by nitrogen availability, an increase in seed mass per plant results from increase in seed nitrogen per plant and/or from decrease in seed nitrogen concentration ([N]). Meta-analysis reveals that the increase in seed mass per plant under elevated [CO(2)] is mainly due to increase in seed nitrogen per plant rather than seed [N] dilution. Nitrogen-fixing legumes enhanced nitrogen acquisition more than non-nitrogen-fixers, resulting in a large increase in seed mass per plant. In Poaceae, an increase in seed mass per plant was also caused by a decrease in seed [N]. Greater carbon allocation to albumen (endosperm and/or perisperm) than the embryo may account for [N] reduction in grass seeds. These differences in CO(2) response of seed production among functional groups may affect their fitness, leading to changes in species composition in the future high-[CO(2)] ecosystem.

  4. Widespread seed limitation affects plant density but not population trajectory in the invasive plant Centaurea solstitialis.

    PubMed

    Swope, Sarah M; Parker, Ingrid M

    2010-09-01

    In some plant populations, the availability of seeds strongly regulates recruitment. However, a scarcity of germination microsites, granivory or density-dependent mortality can reduce the number of plants that germinate or survive to flower. The relative strengths of these controls are unknown for most plant populations and for exotic invaders in particular. We conducted a seed addition experiment with a granivore exclusion treatment in a field setting to explore how these factors interact to regulate populations of the widespread invader Centaurea solstitialis (yellow starthistle) at three study sites across the plant's range in California. We coupled the experimental approach with observational studies within established C. solstitialis populations to estimate seed rain, recruitment and mortality at natural densities. Seed limitation occurred in both experimental and observational plots in all populations. Although vertebrate granivores were active at each site, they had no effect on C. solstitialis recruitment. Density increased mortality, but the effect was variable and weak relative to its effect on fecundity. The seed limitation that was evident at the seedling stage persisted to flowering. Seed-limited populations such as these ought to be highly sensitive to losses to seed predators, and many biological control agents, including those established for C. solstitialis, are seed predators. However, flowering plant density was decoupled from seed production by a strong compensatory response in the surviving plants; seed production was nearly constant in plots across all seed addition levels. Thus, flowering plant density is reduced by the established biocontrol agents, but seed production compensates to replace the population every generation, and no long-term decline is predicted.

  5. Is 'peak N' key to understanding the timing of flowering in annual plants?

    PubMed

    Guilbaud, Camille S E; Dalchau, Neil; Purves, Drew W; Turnbull, Lindsay A

    2015-01-01

    Flowering time in annual plants has large fitness consequences and has been the focus of theoretical and empirical study. Previous theory has concluded that flowering time has evolved over evolutionary time to maximize fitness over a particular season length. We introduce a new model where flowering is cued by a growth-rate rule (peak nitrogen (N)). Flowering is therefore sensitive to physiological parameters and to current environmental conditions, including N availability and the presence of competitors. The model predicts that, when overall conditions are suitable for flowering, plants should never flower after 'peak N', the point during development when the whole-plant N uptake rate reaches its maximum. Our model further predicts correlations between flowering time and vegetative growth rates, and that the response to increased N depends heavily on how this extra N is made available. We compare our predictions to observations in the literature. We suggest that annual plants may have evolved to use growth-rate rules as part of the cue for flowering, allowing them to smoothly and optimally adjust their flowering time to a wide range of local conditions. If so, there are widespread implications for the study of the molecular biology behind flowering pathways.

  6. PMI: Plant-Microbe Interfaces (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Schadt, Christopher

    2013-03-01

    Christopher Schadt of Oak Ridge National Laboratory on "Plant-Microbe Interactions" in the context of poplar trees at the 8th Annual Genomics of Energy & Environment Meeting on March 27, 2013 held in Walnut Creek, Calif.

  7. Inter-annual plasticity of squid life history and population structure: ecological and management implications.

    PubMed

    Pecl, G T; Moltschaniwskyj, N A; Tracey, S R; Jordan, A R

    2004-05-01

    Population size and structure, as well as individual growth rates, condition, and reproductive output, respond to environmental factors, particularly in short-lived and fast-growing squid species. We need to understand the mechanisms through which populations respond to environmental conditions, to predict when or if established relationships, used as management tools to forecast recruitment strength, might break down completely. Identifying characteristics of successful recruits who have grown under different environmental scenarios may improve our understanding of the mechanistic connections between environmental conditions and the temporal variation in life history characteristics that ultimately affect recruitment. This 5-year study sought to determine the association between key life history characteristics of southern calamary Sepioteuthis australis (growth rate, body size, and patterns of repro-somatic energy allocation) and the environmental conditions experienced by individuals on the east coast of Tasmania, Australia. Among years, all population and individual parameters examined were highly variable, despite the environmental regime during the study not encompassing the extremes that may occur in this dynamic region. Temperature was not clearly associated with any of the individual or population differences observed. Populations of apparently similar abundance were composed of individuals with strikingly different biological characteristics, therefore seeking relationships between abundance and environmental parameters at gross levels did not shed light on the mechanisms responsible for population size. Importantly, inter-annual differences in squid size, condition, reproductive investment, and possibly growth rate, were sex-specific, indicating that males and females responded differently to similar factors. Among years differences in body size were extreme, both among the male component of the population and between genders. The relative importance of

  8. Variation in plant defences among populations of a range-expanding plant: consequences for trophic interactions.

    PubMed

    Fortuna, Taiadjana M; Eckert, Silvia; Harvey, Jeffrey A; Vet, Louise E M; Müller, Caroline; Gols, Rieta

    2014-12-01

    Although plant-herbivore-enemy interactions have been studied extensively in cross-continental plant invasions, little is known about intra-continental range expanders, despite their rapid spread globally. Using an ecological and metabolomics approach, we compared the insect performance of a generalist and specialist herbivore and a parasitoid, as well as plant defence traits, among native, exotic invasive and exotic non-invasive populations of the Turkish rocket, Bunias orientalis, a range-expanding species across parts of Eurasia. In the glasshouse, the generalist herbivore, Mamestra brassicae, and its parasitoid, Microplitis mediator, performed better on non-native than on native plant populations. Insect performance did not differ between the two non-native origins. By contrast, the specialist herbivore, Pieris brassicae, developed poorly on all populations. Differences in trichome densities and in the metabolome, particularly in the family-specific secondary metabolites (i.e. glucosinolates), may explain population-related variation in the performance of the generalist herbivore and its parasitoid. Total glucosinolate concentrations were significantly induced by herbivory, particularly in native populations. Native populations of B. orientalis are generally better defended than non-native populations. The role of insect herbivores and dietary specialization as a selection force on defence traits in the range-expanding B. orientalis is discussed. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  9. Kelp biomass production: yield, genetics, and planting technology. Annual report, January 1983-August 1984. Technical report

    SciTech Connect

    Neushul, M.; Harger, B.W.W.

    1985-01-01

    Progress was made toward the long-term goal of growing macroalgae in the sea as a future source of substitute natural gas. The annual report discusses progress made to: (1) measure macroalgal yield, (2) enhance yield by row planting and selective harvesting, (3) genetically breed high-producing plants, (4) devise methods for planting kelps and (5) maintain and extend collaborative research efforts and communication with scientists working on macroalgal biomass production in Japan, China and elsewhere. The report discusses kelp biology and macroalgal mariculture in general terms, the theories that have been proposed and the existing data base in the scientific literature. Particular attention is given to new techniques used to make in-the-sea hydrodynamic and light-climate measurements and microspectrophotometric measurements of DNA levels in kelp sporophytes and gametophytes.

  10. INTRAPOPULATION DIFFERENTIATION IN ANNUAL PLANTS. III. THE CONTRASTING EFFECTS OF INTRA- AND INTERSPECIFIC COMPETITION.

    PubMed

    Linhart, Yan B

    1988-09-01

    The roles of intraspecific and interspecific competition in producing differentiation within populations of Veronica peregrina were studied in two populations under controlled, greenhouse conditions. In nature, each population spans an environmental gradient across the center and sides of a temporary, vernal pool in California. Individuals at the center are subjected to intense intraspecific competition produced by high densities (to 30 seedlings/cm(2) ) generated by quasi-simultaneous germination (90% of seeds germinate in one week). Individuals at the periphery are subjected to interspecific competition with grasses, which shade out the Veronica 4-6 weeks after the onset of winter growth. I predicted that 1) when grown under immediate intraspecific competition in the greenhouse, offspring of plants from the central subpopulation (C) would perform better (i.e., grow larger and produce more seeds) than those from the periphery (P) and that 2) when grown under delayed interspecific competition provided by Agrostis tenuis and Lollium multiflorum, offspring of plants from the periphery would perform better than those from the center. Both predictions were confirmed. The center-periphery differences were pronounced and statistically significant in an undisturbed population (V-2), while in a population disturbed by yearly plowing (V-3), the differences tended to be consistent with those in V-2 but seldom significant. Distribution of variability tended to be positively skewed and/or leptokurtic in subpopulations grown under "foreign" competition (i.e., intraspecific for P plants and interspecific for C plants) but was normally distributed following exposure to "familiar" competition. Timing of competition affected many results. There were four additional significant differences between the central and peripheral subpopulations. 1) Germination rate: the faster rate in central plants can be advantageous under immediate intraspecific competition. The slower rate in

  11. Aerial and soil seed banks enable populations of an annual species to cope with an unpredictable dune ecosystem

    PubMed Central

    Gao, Ruiru; Yang, Xuejun; Yang, Fan; Wei, Lingling; Huang, Zhenying; Walck, Jeffrey L.

    2014-01-01

    Background and Aims Simultaneous formation of aerial and soil seed banks by a species provides a mechanism for population maintenance in unpredictable environments. Eolian activity greatly affects growth and regeneration of plants in a sand dune system, but we know little about the difference in the contributions of these two seed banks to population dynamics in sand dunes. Methods Seed release, germination, seedling emergence and survival of a desert annual, Agriophyllum squarrosum (Chenopodiaceae), inhabiting the Ordos Sandland in China, were determined in order to explore the different functions of the aerial and soil seed banks. Key Results The size of the aerial seed bank was higher than that of the soil seed bank throughout the growing season. Seed release was positively related to wind velocity. Compared with the soil seed bank, seed germination from the aerial seed bank was lower at low temperature (5/15 °C night/day) but higher in the light. Seedling emergence from the soil seed bank was earlier than that from the aerial seed bank. Early-emerged (15 April–15 May) seedlings died due to frost, but seedlings that emerged during the following months survived to reproduce successfully. Conclusions The timing of seed release and different germination behaviour resulted in a temporal heterogeneity of seedling emergence and establishment between the two seed banks. The study suggests that a bet-hedging strategy for the two seed banks enables A. squarrosum populations to cope successfully with the unpredictable desert environment. PMID:24918206

  12. Physiological variation among native and exotic winter annual plants associated with microbiotic crusts in the Mojave Desert

    USGS Publications Warehouse

    DeFalco, L.A.; Detling, J.K.; Tracy, C.R.; Warren, S.D.

    2001-01-01

    Microbiotic crusts are important components of many aridland soils. Research on crusts typically focuses on the increase in soil fertility due to N-fixing micro-organisms, the stabilization of soils against water and wind erosion and the impact of disturbance on N-cycling. The effect of microbiotic crusts on the associated plant community has received little attention. We quantified the influence of crusts on the production, species diversity, nutrient content and water relations of winter annual plant species associated with microbiotic soil crusts in the northeast Mojave Desert. Shoot biomass of winter annuals was 37% greater and plant density was 77% greater on crusts than were biomass and density on soils lacking crust cover (=bare soils). This greater production of annuals on crusts was likely due to enhanced soil conditions including an almost two-fold increase in soil organic matter and inorganic N compared to bare soils. Crusted soils also had 53% greater volumetric water content than bare soils during November and December, the time when winter annuals become established. As plant development progressed into spring, however, soil water availability decreased: More negative plant xylem water potentials were associated with greater plant biomass on crusted soils. Plants associated with microbiotic soil crusts had lower concentrations of N in shoots (mg N g-1 dry mass). However, total shoot N (mg N m-2) was the same in plants growing on the different soil types when biomass production peaked in April. Shoots had similar patterns in their concentration and content of P. Species diversity of annuals was not statistically different between the two soil types. Yet, while native annuals comprised the greatest proportion of shoot biomass on bare soils, exotic forbs and grasses produced more biomass on crusts. Total shoot nutrient content (biomass x concentration) of the two exotic annual species examined was dramatically greater on crusts than bare soils; only one

  13. F-box gene family is expanded in herbaceous annual plants Arabidopsis and rice relative to woody perennial plant Populus

    SciTech Connect

    Yang, Xiaohan; Kalluri, Udaya C; Jawdy, Sara; Gunter, Lee E; Yin, Tongming; Tschaplinski, Timothy J; Weston, David; Ranjan, Priya; Tuskan, Gerald A

    2008-01-01

    F-box proteins are generally responsible for substrate recognition in the Skp1-Cullin-F-box complexes that are involved in protein degradation via the ubiquitin-26S proteosome pathway. In plants, F-box genes influence a variety of biological processes such as leaf senescence, branching, self-incompatibility and responses to biotic and abiotic stresses. The number of F-box genes in Populus (~320) is less than half that found in Arabidopsis (~660) or rice (~680), even though the total number of genes in Populus is equivalent to that in rice and 1.5 times that in Arabidopsis. We performed comparative genomic analysis between the woody perennial plant Populus and the herbaceous annual plants Arabidopsis and rice in order to explicate the functional implications of this large gene family. Our analyses reveal interspecific differences in genomic distribution, orthologous relationship, intron evolution, protein domain structure and gene expression. The set of F-box genes shared by these three species appear to be involved in core biological processes essential for plant growth and development; lineage-specific differences primarily occurred because of an expansion of the F-box genes via tandem duplications in Arabidopsis and rice. The present study provides insights into the relationship between the structure and composition of the F-box gene family in herbaceous and woody species and their associated developmental and physiological features.

  14. Roosting, social organization and the annual cycle in a Kenya population of the bat Pipistrellus nanus

    USGS Publications Warehouse

    O'Shea, Thomas J.

    1980-01-01

    The tiny (3.1–3.8 g) vespcrtilionid bat Pipistrellus nanus was studied in Kenya palm-thatched roofs from May 1973 to July 1974. Roosting social organization and related activities and behavior are described. ♂♂ held diurnal roosting territories where ♀♀ gathered in small and compositionally labile groups, attracted to the most vocal ♂♂. Annual variation in population-wide aspects of social organization follows predictable seasonal changes in climate and predator abundance. Variability between individuals follows a common mammalian pattern: high male competition for ♀, variance in presumed male reproductive success, and a mating system resembling one based on resource defense polygyny. Social organization in this population contrasts with that known from studies of other P. nanus populations.

  15. Evaluate Habitat Use and Population Dynamics of Lampreys in Cedar Creek, 2001 Annual Report.

    SciTech Connect

    Stone, Jennifer; Pirtle, Jody; Barndt, Scott A.

    2002-03-31

    Pacific lamprey (Lampetra tridentata) in the Columbia River Basin have declined to a remnant of their pre-1940s populations and the status of the western brook lamprey (L. richardsoni) is unknown. Identifying the biological and ecological factors limiting lamprey populations is critical to their recovery, but little research has been conducted on these species within the Columbia River Basin. This ongoing, multi-year study examines lamprey populations in Cedar Creek, Washington, a third-order tributary to the Lewis River. This annual report describes the activities and results of the second year of this project. Adult (n = 24), metamorphosed (n = 247), transforming (n = 4), and ammocoete (n = 387) stages from both species were examined in 2001. Lamprey were captured using adult fish ladders, lamprey pots, rotary screw traps, and lamprey electrofishers. Twenty-nine spawning ground surveys were conducted. Nine strategic point-specific habitat surveys were performed to assess habitat requirements of juvenile lamprey.

  16. Rapid evolution accelerates plant population spread in fragmented experimental landscapes.

    PubMed

    Williams, Jennifer L; Kendall, Bruce E; Levine, Jonathan M

    2016-07-29

    Predicting the speed of biological invasions and native species migrations requires an understanding of the ecological and evolutionary dynamics of spreading populations. Theory predicts that evolution can accelerate species' spread velocity, but how landscape patchiness--an important control over traits under selection--influences this process is unknown. We manipulated the response to selection in populations of a model plant species spreading through replicated experimental landscapes of varying patchiness. After six generations of change, evolving populations spread 11% farther than nonevolving populations in continuously favorable landscapes and 200% farther in the most fragmented landscapes. The greater effect of evolution on spread in patchier landscapes was consistent with the evolution of dispersal and competitive ability. Accounting for evolutionary change may be critical when predicting the velocity of range expansions. Copyright © 2016, American Association for the Advancement of Science.

  17. Host preferences of arbuscular mycorrhizal fungi colonizing annual herbaceous plant species in semiarid Mediterranean prairies.

    PubMed

    Torrecillas, E; Alguacil, M M; Roldán, A

    2012-09-01

    In this study, we have analyzed and compared the diversities of the arbuscular mycorrhizal fungi (AMF) colonizing the roots of five annual herbaceous species (Hieracium vulgare, Stipa capensis, Anagallis arvensis, Carduus tenuiflorus, and Avena barbata) and a perennial herbaceous species (Brachypodium retusum). Our goal was to determine the differences in the communities of the AMF among these six plant species belonging to different families, using B. retusum as a reference. The AMF small-subunit rRNA genes (SSU) were subjected to nested PCR, cloning, sequencing, and phylogenetic analysis. Thirty-six AMF phylotypes, belonging to Glomus group A, Glomus group B, Diversispora, Paraglomus, and Ambispora, were identified. Five sequence groups identified in this study clustered to known glomalean species or isolates: group Glomus G27 to Glomus intraradices, group Glomus G19 to Glomus iranicum, group Glomus G10 to Glomus mosseae, group Glomus G1 to Glomus lamellosum/etunicatum/luteum, and group Ambispora 1 to Ambispora fennica. The six plant species studied hosted different AMF communities. A certain trend of AMF specificity was observed when grouping plant species by taxonomic families, highlighting the importance of protecting and even promoting the native annual vegetation in order to maintain the biodiversity and productivity of these extreme ecosystems.

  18. Host Preferences of Arbuscular Mycorrhizal Fungi Colonizing Annual Herbaceous Plant Species in Semiarid Mediterranean Prairies

    PubMed Central

    Torrecillas, E.; Roldán, A.

    2012-01-01

    In this study, we have analyzed and compared the diversities of the arbuscular mycorrhizal fungi (AMF) colonizing the roots of five annual herbaceous species (Hieracium vulgare, Stipa capensis, Anagallis arvensis, Carduus tenuiflorus, and Avena barbata) and a perennial herbaceous species (Brachypodium retusum). Our goal was to determine the differences in the communities of the AMF among these six plant species belonging to different families, using B. retusum as a reference. The AMF small-subunit rRNA genes (SSU) were subjected to nested PCR, cloning, sequencing, and phylogenetic analysis. Thirty-six AMF phylotypes, belonging to Glomus group A, Glomus group B, Diversispora, Paraglomus, and Ambispora, were identified. Five sequence groups identified in this study clustered to known glomalean species or isolates: group Glomus G27 to Glomus intraradices, group Glomus G19 to Glomus iranicum, group Glomus G10 to Glomus mosseae, group Glomus G1 to Glomus lamellosum/etunicatum/luteum, and group Ambispora 1 to Ambispora fennica. The six plant species studied hosted different AMF communities. A certain trend of AMF specificity was observed when grouping plant species by taxonomic families, highlighting the importance of protecting and even promoting the native annual vegetation in order to maintain the biodiversity and productivity of these extreme ecosystems. PMID:22752164

  19. Interacting coexistence mechanisms in annual plant communities: Frequency-dependent predation and the storage effect.

    PubMed

    Kuang, Jessica J; Chesson, Peter

    2010-02-01

    We study frequency-dependent seed predation (FDP) in a model of competing annual plant species in a variable environment. The combination of a variable environment and competition leads to the storage-effect coexistence mechanism (SE), which is a leading hypothesis for coexistence of desert annual plants. However, seed predation in such systems demands attention to coexistence mechanisms associated with predation. FDP is one such mechanism, which promotes coexistence by shifting predation to more abundant plant species, facilitating the recovery of species perturbed to low density. When present together, FDP and SE interact, undermining each other's effects. Predation weakens competition, and therefore weakens mechanisms associated with competition: here SE. However, the direct effect of FDP in promoting coexistence can compensate or more than compensate for this weakening of SE. On the other hand, the environmental variation necessary for SE weakens FDP. With high survival of dormant seeds, SE can be strong enough to compensate, or overcompensate, for the decline in FDP, provided predation is not too strong. Although FDP and SE may simultaneously contribute to coexistence, their combined effect is less than the sum of their separate effects, and is often less than the effect of the stronger mechanism when present alone. Copyright 2009 Elsevier Inc. All rights reserved.

  20. Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: II. Annual plants

    USGS Publications Warehouse

    Berry, Kristin H.; Mack, Jeremy S.; Weigand, James F.; Gowan, Timothy A.; LaBerteaux, Denise

    2015-01-01

    We studied recovery of winter annual plants in a 97-m wide disturbed aqueduct corridor in the Mojave Desert 36 years after construction. We established plots at 0, 20, and 40 m from the road verge at the corridor center and at 100 m in undisturbed vegetation. We recorded 47 annual species, of which 41 were native and six were exotic. Exotic species composed from 64 to 91% of total biomass. We describe a bilateral process of recovery: from the road verge to the outward edge of the corridor and from undisturbed habitat into the corridor. Native annual plants significantly increased in richness from road verge to undisturbed vegetation, but not in density, biomass, or cover. In contrast, exotic annual plants increased in density, biomass, cover and richness with increasing distance from the road verge. The species of colonizing shrubs and type of canopy cover affected density, biomass, and richness of annuals. Species composition of native annuals differed significantly by distance, suggesting secondary succession. In general, native annuals were closer to achieving recovery on the 40-m plots than at the road verge. Recovery estimates were in centuries and dependent on location, canopy type, and whether considering all annuals or natives only.

  1. Risk-informed assessment of regulatory and design requirements for future nuclear power plants. Annual report

    SciTech Connect

    2000-08-01

    OAK B188 Risk-informed assessment of regulatory and design requirements for future nuclear power plants. Annual report. The overall goal of this research project is to support innovation in new nuclear power plant designs. This project is examining the implications, for future reactors and future safety regulation, of utilizing a new risk-informed regulatory system as a replacement for the current system. This innovation will be made possible through development of a scientific, highly risk-formed approach for the design and regulation of nuclear power plants. This approach will include the development and/or confirmation of corresponding regulatory requirements and industry standards. The major impediment to long term competitiveness of new nuclear plants in the U.S. is the capital cost component--which may need to be reduced on the order of 35% to 40% for Advanced Light Water Reactors (ALWRS) such as System 80+ and Advanced Boiling Water Reactor (ABWR). The required cost reduction for an ALWR such as AP600 or AP1000 would be expected to be less. Such reductions in capital cost will require a fundamental reevaluation of the industry standards and regulatory bases under which nuclear plants are designed and licensed. Fortunately, there is now an increasing awareness that many of the existing regulatory requirements and industry standards are not significantly contributing to safety and reliability and, therefore, are unnecessarily adding to nuclear plant costs. Not only does this degrade the economic competitiveness of nuclear energy, it results in unnecessary costs to the American electricity consumer. While addressing these concerns, this research project will be coordinated with current efforts of industry and NRC to develop risk-informed, performance-based regulations that affect the operation of the existing nuclear plants; however, this project will go further by focusing on the design of new plants.

  2. Evolution in plant populations as a driver of ecological changes in arthropod communities

    PubMed Central

    Johnson, Marc T.J.; Vellend, Mark; Stinchcombe, John R.

    2009-01-01

    Heritable variation in traits can have wide-ranging impacts on species interactions, but the effects that ongoing evolution has on the temporal ecological dynamics of communities are not well understood. Here, we identify three conditions that, if experimentally satisfied, support the hypothesis that evolution by natural selection can drive ecological changes in communities. These conditions are: (i) a focal population exhibits genetic variation in a trait(s), (ii) there is measurable directional selection on the trait(s), and (iii) the trait(s) under selection affects variation in a community variable(s). When these conditions are met, we expect evolution by natural selection to cause ecological changes in the community. We tested these conditions in a field experiment examining the interactions between a native plant (Oenothera biennis) and its associated arthropod community (more than 90 spp.). Oenothera biennis exhibited genetic variation in several plant traits and there was directional selection on plant biomass, life-history strategy (annual versus biennial reproduction) and herbivore resistance. Genetically based variation in biomass and life-history strategy consistently affected the abundance of common arthropod species, total arthropod abundance and arthropod species richness. Using two modelling approaches, we show that evolution by natural selection in large O. biennis populations is predicted to cause changes in the abundance of individual arthropod species, increases in the total abundance of arthropods and a decline in the number of arthropod species. In small O. biennis populations, genetic drift is predicted to swamp out the effects of selection, making the evolution of plant populations unpredictable. In short, evolution by natural selection can play an important role in affecting the dynamics of communities, but these effects depend on several ecological factors. The framework presented here is general and can be applied to other systems to

  3. Evolution in plant populations as a driver of ecological changes in arthropod communities.

    PubMed

    Johnson, Marc T J; Vellend, Mark; Stinchcombe, John R

    2009-06-12

    Heritable variation in traits can have wide-ranging impacts on species interactions, but the effects that ongoing evolution has on the temporal ecological dynamics of communities are not well understood. Here, we identify three conditions that, if experimentally satisfied, support the hypothesis that evolution by natural selection can drive ecological changes in communities. These conditions are: (i) a focal population exhibits genetic variation in a trait(s), (ii) there is measurable directional selection on the trait(s), and (iii) the trait(s) under selection affects variation in a community variable(s). When these conditions are met, we expect evolution by natural selection to cause ecological changes in the community. We tested these conditions in a field experiment examining the interactions between a native plant (Oenothera biennis) and its associated arthropod community (more than 90 spp.). Oenothera biennis exhibited genetic variation in several plant traits and there was directional selection on plant biomass, life-history strategy (annual versus biennial reproduction) and herbivore resistance. Genetically based variation in biomass and life-history strategy consistently affected the abundance of common arthropod species, total arthropod abundance and arthropod species richness. Using two modelling approaches, we show that evolution by natural selection in large O. biennis populations is predicted to cause changes in the abundance of individual arthropod species, increases in the total abundance of arthropods and a decline in the number of arthropod species. In small O. biennis populations, genetic drift is predicted to swamp out the effects of selection, making the evolution of plant populations unpredictable. In short, evolution by natural selection can play an important role in affecting the dynamics of communities, but these effects depend on several ecological factors. The framework presented here is general and can be applied to other systems to

  4. Waste Isolation Pilot Plant Annual Site Environmental Report for 2014. Emended

    SciTech Connect

    none,

    2015-09-01

    The purpose of the Waste Isolation Pilot Plant (WIPP) Annual Site Environmental Report for 2014 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1B, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data to: Characterize site environmental management performance; Summarize environmental occurrences and responses reported during the calendar year (CY); Confirm compliance with environmental standards and requirements; Highlight significant environmental accomplishments, including progress toward the DOE environmental sustainability goals made through implementation of the WIPP Environmental Management System (EMS).

  5. Population, Behavioural and Physiological Responses of an Urban Population of Black Swans to an Intense Annual Noise Event

    PubMed Central

    Payne, Catherine J.; Jessop, Tim S.; Guay, Patrick-Jean; Johnstone, Michele; Feore, Megan; Mulder, Raoul A.

    2012-01-01

    Wild animals in urban environments are exposed to a broad range of human activities that have the potential to disturb their life history and behaviour. Wildlife responses to disturbance can range from emigration to modified behaviour, or elevated stress, but these responses are rarely evaluated in concert. We simultaneously examined population, behavioural and hormonal responses of an urban population of black swans Cygnus atratus before, during and after an annual disturbance event involving large crowds and intense noise, the Australian Formula One Grand Prix. Black swan population numbers were lowest one week before the event and rose gradually over the course of the study, peaking after the event, suggesting that the disturbance does not trigger mass emigration. We also found no difference in the proportion of time spent on key behaviours such as locomotion, foraging, resting or self-maintenance over the course of the study. However, basal and capture stress-induced corticosterone levels showed significant variation, consistent with a modest physiological response. Basal plasma corticosterone levels were highest before the event and decreased over the course of the study. Capture-induced stress levels peaked during the Grand Prix and then also declined over the remainder of the study. Our results suggest that even intensely noisy and apparently disruptive events may have relatively low measurable short-term impact on population numbers, behaviour or physiology in urban populations with apparently high tolerance to anthropogenic disturbance. Nevertheless, the potential long-term impact of such disturbance on reproductive success, individual fitness and population health will need to be carefully evaluated. PMID:23024783

  6. Population, behavioural and physiological responses of an urban population of black swans to an intense annual noise event.

    PubMed

    Payne, Catherine J; Jessop, Tim S; Guay, Patrick-Jean; Johnstone, Michele; Feore, Megan; Mulder, Raoul A

    2012-01-01

    Wild animals in urban environments are exposed to a broad range of human activities that have the potential to disturb their life history and behaviour. Wildlife responses to disturbance can range from emigration to modified behaviour, or elevated stress, but these responses are rarely evaluated in concert. We simultaneously examined population, behavioural and hormonal responses of an urban population of black swans Cygnus atratus before, during and after an annual disturbance event involving large crowds and intense noise, the Australian Formula One Grand Prix. Black swan population numbers were lowest one week before the event and rose gradually over the course of the study, peaking after the event, suggesting that the disturbance does not trigger mass emigration. We also found no difference in the proportion of time spent on key behaviours such as locomotion, foraging, resting or self-maintenance over the course of the study. However, basal and capture stress-induced corticosterone levels showed significant variation, consistent with a modest physiological response. Basal plasma corticosterone levels were highest before the event and decreased over the course of the study. Capture-induced stress levels peaked during the Grand Prix and then also declined over the remainder of the study. Our results suggest that even intensely noisy and apparently disruptive events may have relatively low measurable short-term impact on population numbers, behaviour or physiology in urban populations with apparently high tolerance to anthropogenic disturbance. Nevertheless, the potential long-term impact of such disturbance on reproductive success, individual fitness and population health will need to be carefully evaluated.

  7. Comparison of signaling interactions determining annual and perennial plant growth in response to low temperature

    PubMed Central

    Wingler, Astrid

    2015-01-01

    Low temperature inhibits plant growth despite the fact that considerable rates of photosynthetic activity can be maintained. Instead of lower rates of photosynthesis, active inhibition of cell division and expansion is primarily responsible for reduced growth. This results in sink limitation and enables plants to accumulate carbohydrates that act as compatible solutes or are stored throughout the winter to enable re-growth in spring. Regulation of growth in response to temperature therefore requires coordination with carbon metabolism, e.g., via the signaling metabolite trehalose-6-phosphate. The phytohormones gibberellin (GA) and jasmonate (JA) play an important role in regulating growth in response to temperature. Growth restriction at low temperature is mainly mediated by DELLA proteins, whose degradation is promoted by GA. For annual plants, it has been shown that the GA/DELLA pathway interacts with JA signaling and C-repeat binding factor dependent cold acclimation, but these interactions have not been explored in detail for perennials. Growth regulation in response to seasonal factors is, however, particularly important in perennials, especially at high latitudes. In autumn, growth cessation in trees is caused by shortening of the daylength in interaction with phytohormone signaling. In perennial grasses seasonal differences in the sensitivity to GA may enable enhanced growth in spring. This review provides an overview of the signaling interactions that determine plant growth at low temperature and highlights gaps in our knowledge, especially concerning the seasonality of signaling responses in perennial plants. PMID:25628637

  8. Pollinator identity and spatial isolation influence multiple paternity in an annual plant.

    PubMed

    Rhodes, Matthew K; Fant, Jeremie B; Skogen, Krissa A

    2017-03-23

    The occurrence and extent of multiple paternity is an important component of variation in plant mating dynamics. However, links between pollinator activity and multiple paternity are generally lacking, especially for plant species that attract functionally diverse floral visitors. In this study, we separated the influence of two functionally distinct floral visitors (hawkmoths and solitary bees) and characterized their impacts on multiple paternity in a self-incompatible, annual forb, Oenothera harringtonii (Onagraceae). We also situated pollinator-mediated effects in a spatial context by linking variation in multiple paternity to variation in plant spatial isolation. We documented pronounced differences in the number of paternal sires as function of pollinator identity: on average, the primary pollinator (hawkmoths) facilitated mating with nearly twice as many pollen donors relative to the secondary pollinator (solitary bees). This effect was consistent for both isolated and non-isolated individuals, but spatial isolation imposed pronounced reductions on multiple paternity regardless of pollinator identity. Considering that pollinator abundance and pollen dispersal distance did not vary significantly with pollinator identity, we attribute variation in realized mating dynamics primarily to differences in pollinator morphology and behavior as opposed to pollinator abundance or mating incompatibility arising from underlying spatial genetic structure. Our findings demonstrate that functionally distinct pollinators can have strongly divergent effects on polyandry in plants and further suggest that both pollinator identity and spatial heterogeneity have important roles in plant mating dynamics. This article is protected by copyright. All rights reserved.

  9. Effective population size is positively correlated with levels of adaptive divergence among annual sunflowers.

    PubMed

    Strasburg, Jared L; Kane, Nolan C; Raduski, Andrew R; Bonin, Aurélie; Michelmore, Richard; Rieseberg, Loren H

    2011-05-01

    The role of adaptation in the divergence of lineages has long been a central question in evolutionary biology, and as multilocus sequence data sets have become available for a wide range of taxa, empirical estimates of levels of adaptive molecular evolution are increasingly common. Estimates vary widely among taxa, with high levels of adaptive evolution in Drosophila, bacteria, and viruses but very little evidence of widespread adaptive evolution in hominids. Although estimates in plants are more limited, some recent work has suggested that rates of adaptive evolution in a range of plant taxa are surprisingly low and that there is little association between adaptive evolution and effective population size in contrast to patterns seen in other taxa. Here, we analyze data from 35 loci for six sunflower species that vary dramatically in effective population size. We find that rates of adaptive evolution are positively correlated with effective population size in these species, with a significant fraction of amino acid substitutions driven by positive selection in the species with the largest effective population sizes but little or no evidence of adaptive evolution in species with smaller effective population sizes. Although other factors likely contribute as well, in sunflowers effective population size appears to be an important determinant of rates of adaptive evolution.

  10. Effective Population Size Is Positively Correlated with Levels of Adaptive Divergence among Annual Sunflowers

    PubMed Central

    Strasburg, Jared L.; Kane, Nolan C.; Raduski, Andrew R.; Bonin, Aurélie; Michelmore, Richard; Rieseberg, Loren H.

    2011-01-01

    The role of adaptation in the divergence of lineages has long been a central question in evolutionary biology, and as multilocus sequence data sets have become available for a wide range of taxa, empirical estimates of levels of adaptive molecular evolution are increasingly common. Estimates vary widely among taxa, with high levels of adaptive evolution in Drosophila, bacteria, and viruses but very little evidence of widespread adaptive evolution in hominids. Although estimates in plants are more limited, some recent work has suggested that rates of adaptive evolution in a range of plant taxa are surprisingly low and that there is little association between adaptive evolution and effective population size in contrast to patterns seen in other taxa. Here, we analyze data from 35 loci for six sunflower species that vary dramatically in effective population size. We find that rates of adaptive evolution are positively correlated with effective population size in these species, with a significant fraction of amino acid substitutions driven by positive selection in the species with the largest effective population sizes but little or no evidence of adaptive evolution in species with smaller effective population sizes. Although other factors likely contribute as well, in sunflowers effective population size appears to be an important determinant of rates of adaptive evolution. PMID:20952500

  11. 78 FR 24603 - Endangered and Threatened Wildlife and Plants; Annual Notice of Findings on Resubmitted Petitions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ...In this Annual Notice of Review (ANOR) of foreign species, we present an updated list of plant and animal species foreign to the United States that we regard as candidates for addition to the Lists of Endangered and Threatened Wildlife and Plants under the Endangered Species Act of 1973, as amended. This review ensures that we focus conservation efforts on those species at greatest risk first. Overall, this ANOR recognizes one new candidate and removes one species from candidate status. The current number of foreign species that are candidates for listing is 20. Based on our current review, we find that 20 species continue to warrant listing, but their listing remains precluded by higher priority proposals to determine whether any species is an endangered species or a threatened species.

  12. Usefulness of LANDSAT data for monitoring plant development and range conditions in California's annual grassland

    NASA Technical Reports Server (NTRS)

    Carneggie, D. M.; Degloria, S. D.; Colwell, R. N.

    1975-01-01

    A network of sampling sites throughout the annual grassland region of California was established to correlate plant growth stages and forage production to climatic and other environmental factors. Plant growth and range conditions were further related to geographic location and seasonal variations. A sequence of LANDSAT data was obtained covering critical periods in the growth cycle. This was analyzed by both photointerpretation and computer aided techniques. Image characteristics and spectral reflectance data were then related to forage production, range condition, range site and changing growth conditions. It was determined that repeat sequences with LANDSAT color composite images do provide a means for monitoring changes in range condition. Spectral radiance data obtained from magnetic tape can be used to determine quantitatively the critical stages in the forage growth cycle. A computer ratioing technique provided a sensitive indicator of changes in growth stages and an indication of the relative differences in forage production between range sites.

  13. Modelling the impact of climate change on woody plant population dynamics in South African savanna.

    PubMed

    Tews, Jörg; Jeltsch, Florian

    2004-12-17

    In Southern Africa savannas climate change has been proposed to alter rainfall, the most important environmental driver for woody plants. Woody plants are a major component of savanna vegetation determining rangeland condition and biodiversity. In this study we use a spatially explicit, stochastic computer model to assess the impact of climate change on the population dynamics of Grewia flava, a common, fleshy-fruited shrub species in the southern Kalahari. Understanding the population dynamics of Grewia flava is a crucial task, because it is widely involved in the shrub/bush encroachment process, a major concern for rangeland management due to its adverse effect on livestock carrying capacity and biodiversity. For our study we consider four climate change scenarios that have been proposed for the southern Kalahari for the coming decades: (1) an increase in annual precipitation by 30-40%, (2) a decrease by 5-15%, (3) an increase in variation of extreme rainfall years by 10-20%, (4) and increase in temporal auto-correlation, i.e. increasing length and variation of periodic rainfall oscillations related to El Nino/La Nina phenomena. We evaluate the slope z of the time-shrub density relationship to quantify the population trend. For each climate change scenario we then compared the departure of z from typical stable population dynamics under current climatic conditions. Based on the simulation experiments we observed a positive population trend for scenario (1) and a negative trend for scenario (2). In terms of the projected rates of precipitation change for scenario (3) and (4) population dynamics were found to be relatively stable. However, for a larger increase in inter-annual variation or in temporal auto-correlation of rainfall population trends were negative, because favorable rainfall years had a limited positive impact due to the limited shrub carrying capacity. We conclude that a possible increase in precipitation will strongly facilitate shrub encroachment

  14. Source population characteristics affect heterosis following genetic rescue of fragmented plant populations

    PubMed Central

    Pickup, M.; Field, D. L.; Rowell, D. M.; Young, A. G.

    2013-01-01

    Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F1, F2, F3) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic diversity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically diverse populations. PMID:23173202

  15. Correlations between U.S. county annual cancer incidence and population density

    PubMed Central

    Vares, David AE; St-Pierre, Linda S; Persinger, Michael A

    2015-01-01

    Population density implicitly involves specific distances between living individuals who exhibit biophysical forces and energies. Objective was to investigate major data bases of cancer incidence and population data to help understand the emergent properties of diseases that become apparent only when large populations and areas are considered. Correlation analyses of the annual incidence (years 2007 to 2011) of cancer in counties (2,885) of the U.S. and population densities were convergent with these quantitative predictions and suggested an inflection threshold around 50 people per square mile. The potential role of subtle or even “non-local” factors coupled to averaged population density in the viability and mortality of the human species may serve as alternative explanations to the attribution of malignancy to “chance” factors. Calculations indicated average distances between the electric force dipole of the brains or bodies of human beings generate forces known to affect DNA extension and when distributed over the Compton wavelength of the electron could produce energies sufficient to affect the binding of base nucleotides. An inclusive science of human ecology might benefit from considering subtle forces and energies associated with the individual members within the habitat that could determine the probability of cellular anomalies. PMID:26807326

  16. Correlations between U.S. county annual cancer incidence and population density.

    PubMed

    Vares, David Ae; St-Pierre, Linda S; Persinger, Michael A

    2015-01-01

    Population density implicitly involves specific distances between living individuals who exhibit biophysical forces and energies. Objective was to investigate major data bases of cancer incidence and population data to help understand the emergent properties of diseases that become apparent only when large populations and areas are considered. Correlation analyses of the annual incidence (years 2007 to 2011) of cancer in counties (2,885) of the U.S. and population densities were convergent with these quantitative predictions and suggested an inflection threshold around 50 people per square mile. The potential role of subtle or even "non-local" factors coupled to averaged population density in the viability and mortality of the human species may serve as alternative explanations to the attribution of malignancy to "chance" factors. Calculations indicated average distances between the electric force dipole of the brains or bodies of human beings generate forces known to affect DNA extension and when distributed over the Compton wavelength of the electron could produce energies sufficient to affect the binding of base nucleotides. An inclusive science of human ecology might benefit from considering subtle forces and energies associated with the individual members within the habitat that could determine the probability of cellular anomalies.

  17. Planting geometry and plant population affect dryland maize grain yield and harvest index

    USDA-ARS?s Scientific Manuscript database

    Water for dryland grain production in the Texas panhandle is limited. Agronomic practices such as reduction in plant population or change in sowing time may help increase maize (Zea mays L.) yield potential. Tiller formation under dryland conditions leads to more vegetative growth and reduced yield....

  18. Model calculating annual mean atmospheric dispersion factor for coastal site of nuclear power plant.

    PubMed

    Hu, E B; Chen, J Y; Yao, R T; Zhang, M S; Gao, Z R; Wang, S X; Jia, P R; Liao, Q L

    2001-07-01

    This paper describes an atmospheric dispersion field experiment performed on the coastal site of nuclear power plant in the east part of China during 1995 to 1996. The three-dimension joint frequency are obtained by hourly observation of wind and temperature on a 100 m high tower; the frequency of the "event day of land and sea breezes" are given by observation of surface wind and land and sea breezes; the diffusion parameters are got from measurements of turbulent and wind tunnel simulation test. A new model calculating the annual mean atmospheric dispersion factor for coastal site of nuclear power plant is developed and established. This model considers not only the effect from mixing release and mixed layer but also the effect from the internal boundary layer and variation of diffusion parameters due to the distance from coast. The comparison between results obtained by the new model and current model shows that the ratio of annual mean atmospheric dispersion factor gained by the new model and the current one is about 2.0.

  19. Woody plant encroachment reduces annual runoff and shifts runoff mechanisms in the tallgrass prairie, USA

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Zou, Chris B.; Stebler, Elaine; Will, Rodney E.

    2017-06-01

    Woody plant encroachment into semiarid and subhumid rangelands is a global phenomenon with important hydrological implications. Observational and experimental results reported both increases and decreases in annual runoff for encroached watersheds and little is known regarding the underlying runoff generation mechanisms. To systematically study the effect of woody plant encroachment on runoff generation processes, seven experimental watersheds were instrumented in 2010, three on grassland sites and four on adjacent sites that were heavily encroached by eastern redcedar (Juniperus virginiana) in the southern Great Plains, USA. Results showed that the runoff coefficient was 1.4 ± 0.6% in eastern redcedar encroached watersheds, significantly lower than 4.4 ± 0.7% in grassland watersheds for the four water years from 2011 to 2014. Eastern redcedar encroachment resulted in reduction of both surface and subsurface flows and the magnitude of reduction depended on annual precipitation. While there were nearly equal contributions between overland flow and subsurface flow, 87% of the total runoff from grassland watersheds occurred under saturated or nearly saturated soil condition, while 86% of runoff under encroached watersheds was generated under unsaturated soil condition, suggesting a shift from saturation excess overland flow to infiltration excess overland flow. These results permitted reconciliation of observed difference of streamflow responses associated with Juniperus spp. encroachment in the region and provided insights to better predict change in water resources under vegetation changes in subhumid regions of the south-central USA.

  20. A stochastic model of chromatin modification: cell population coding of winter memory in plants.

    PubMed

    Satake, Akiko; Iwasa, Yoh

    2012-06-07

    Biological memory, a sustained cellular response to a transient stimulus, has been found in many natural systems. The best example in plants is the winter memory by which plants can flower in favorable conditions in spring. For this winter memory, epigenetic regulation of FLOWERING LOCUS C (FLC), which acts as a floral repressor, plays a key role. Exposure to prolonged periods of cold results in the gradual suppression of FLC, which allows plants to measure the length of cold and to flower only after a sufficiently long winter. Although many genes involved in histone modifications have been isolated, molecular mechanisms of winter memory are not well understood. Here, we develop a model for chromatin modification, in which the dynamics of a single nucleosome are aggregated to on/off behavior of FLC expression at the cellular level and further integrated to a change of FLC expression at the whole-plant level. We propose cell-population coding of winter memory: each cell is described as a bistable system that shows heterogeneous timing of the transition from on to off in FLC expression under cold and measures the length of cold as the proportion of cells in the off state. This mechanism well explains robust FLC regulation and stable inheritance of winter memory after cell division in response to noisy signals. Winter memory lasts longer if deposition of the repressive histone mark occurs faster. A difference in deposition speed would discriminate between stable maintenance of FLC repression in annuals and transient expression in perennials.

  1. Naturalization of plant populations: the role of cultivation and population size and density.

    PubMed

    Minton, Mark S; Mack, Richard N

    2010-10-01

    Field experimentation is required to assess the effects of environmental stochasticity on small immigrant plant populations-a widely understood but largely unexplored aspect of predicting any species' likelihood of naturalization and potential invasion. Cultivation can mitigate this stochasticity, although the outcome for a population under cultivation nevertheless varies enormously from extinction to persistence. Using factorial experiments, we investigated the effects of population size, density, and cultivation (irrigation) on the fate of founder populations for four alien species with different life history characteristics (Echinochloa frumentacea, Fagopyrum esculentum, Helianthus annuus, and Trifolium incarnatum) in eastern Washington, USA. The fate of founder populations was highly variable within and among the 3 years of experimentation and illustrates the often precarious environment encountered by plant immigrants. Larger founder populations produced more seeds (P < 0.001); the role of founder population size, however, differed among years. Irrigation resulted in higher percent survival (P < 0.001) and correspondingly larger net reproductive rate (R(0); P < 0.001). But the minimum level of irrigation for establishment, R(0) > 1, differed among years and species. Sowing density did not affect the likelihood of establishment for any species. Our results underscore the importance of environmental stochasticity in determining the fate of founder populations and the potential of cultivation and large population size in countering the long odds against naturalization. Any implementation of often proposed post-immigration field trials to assess the risk of an alien species becoming naturalized, a requisite step toward invasion, will need to assess different sizes of founder populations and the extent and character of cultivation (intentional or unintentional) that the immigrants might receive.

  2. Portfolio effects, climate change, and the persistence of small populations: analyses on the rare plant Saussurea weberi.

    PubMed

    Abbott, Ronald E; Doak, Daniel F; Peterson, Megan L

    2017-01-23

    The mechanisms that stabilize small populations in the face of environmental variation are crucial to their long-term persistence. Building from diversity-stability concepts in community ecology, within-population diversity is gaining attention as an important component of population stability. Genetic and microhabitat variation within populations can generate diverse responses to common environmental fluctuations, dampening temporal variability across the population as a whole through portfolio effects. Yet, the potential for portfolio effects to operate at small scales within populations or to change with systematic environmental shifts, such as climate change, remain largely unexplored. We tracked the abundance of a rare alpine perennial plant, Saussurea weberi, in 49 1 m(2) plots within a single population over 20 years. We estimated among-plot correlations in log annual growth rate to test for population-level synchrony and quantify portfolio effects across the 20-year study period and also in 5-year subsets based on June temperature quartiles. Asynchrony among plots, due to different plot-level responses to June temperature, reduced overall fluctuations in abundance and the probability of decline in population models, even when accounting for the effects of density dependence on dynamics. However, plots became more synchronous and portfolio effects decreased during the warmest years of the study, suggesting that future climate warming may erode stabilizing mechanisms in populations of this rare plant. This article is protected by copyright. All rights reserved.

  3. 8th Annual Glycoscience Symposium: Integrating Models of Plant Cell Wall Structure, Biosynthesis and Assembly

    SciTech Connect

    Azadi, Paratoo

    2015-09-24

    The Complex Carbohydrate Research Center (CCRC) of the University of Georgia holds a symposium yearly that highlights a broad range of carbohydrate research topics. The 8th Annual Georgia Glycoscience Symposium entitled “Integrating Models of Plant Cell Wall Structure, Biosynthesis and Assembly” was held on April 7, 2014 at the CCRC. The focus of symposium was on the role of glycans in plant cell wall structure and synthesis. The goal was to have world leaders in conjunction with graduate students, postdoctoral fellows and research scientists to propose the newest plant cell wall models. The symposium program closely followed the DOE’s mission and was specifically designed to highlight chemical and biochemical structures and processes important for the formation and modification of renewable plant cell walls which serve as the basis for biomaterial and biofuels. The symposium was attended by both senior investigators in the field as well as students including a total attendance of 103, which included 80 faculty/research scientists, 11 graduate students and 12 Postdoctoral students.

  4. A feasibility study of perennial/annual plant species to restore soils contaminated with heavy metals

    NASA Astrophysics Data System (ADS)

    Zacarías, Montserrat; Beltrán, Margarita; Gilberto Torres, Luis; González, Abelardo

    A feasibility study was carried out to evaluate the application of perennial/annual plant species in a phytoextraction process of a previously washed industrial urban soil contaminated by nickel, arsenic and cupper. The plant species selected for this study were Ipomea (Ipomea variada); grass (Poa pratensis); grass mixture (Festuca rubra, Cynodon dactylon, Lolium multiforum, Pennisetum sp.); Monks Cress (Tropaeolum majus); ficus (Ficus benajamina) and fern (Pteris cretica). Soil was characterized and it presented the following heavy metals concentrations (dry weight): 80 mg of Ni/kg, 456-656 mg of As/kg and 1684-3166 mg of Cu/kg. Germination and survival in contaminated soil tests were conducted, from these, P. pratensis was discarded and the rest of plant species tested were used for the phytoextraction selection test. After 4 months of growth, biomass production was determined, and content of Ni, As and Cu was analyzed in plant’s tissue. Metal biological absorption coefficient (BAC), bio-concentration factor (BCF) and translocation factor (TF), were calculated. Regarding to biomass generation it was observed, in every case, an inhibition of the plant growth compared with blanks sown in a non contaminated soil; inhibition ranged from 22.5% for the Monk cress to 98% for Ipomea. Even though the later presented high BAC, BCF and TF, its growth was severely inhibited, and therefore, due its low biomass generation, it is not recommended for phytoextraction under conditions for this study. Heavy metals concentrations in plant’s tissue (dry weight) were as high as 866 mg Cu/kg and 602 mg As/kg for grass mixture; and 825 mg As/kg was observed for Monks cress. Grass mixture and monks cress had high BAC, BCF and TF, also they had high metal concentrations in its plants tissues and the lowest growth inhibition rates; hence the application in phytoextraction processes of these plants is advisable.

  5. The Annual Burden of Seasonal Influenza in the US Veterans Affairs Population

    PubMed Central

    Young-Xu, Yinong; Russo, Ellyn; Lee, Jason K. H.; Chit, Ayman

    2017-01-01

    Seasonal influenza epidemics have a substantial public health and economic burden in the United States (US). On average, over 200,000 people are hospitalized and an estimated 23,000 people die from respiratory and circulatory complications associated with seasonal influenza virus infections each year. Annual direct medical costs and indirect productivity costs across the US have been found to average respectively at $10.4 billion and $16.3 billion. The objective of this study was to estimate the economic impact of severe influenza-induced illness on the US Veterans Affairs population. The five-year study period included 2010 through 2014. Influenza-attributed outcomes were estimated with a statistical regression model using observed emergency department (ED) visits, hospitalizations, and deaths from the Veterans Health Administration of the Department of Veterans Affairs (VA) electronic medical records and respiratory viral surveillance data from the Centers for Disease Control and Prevention (CDC). Data from VA’s Managerial Cost Accounting system were used to estimate the costs of the emergency department and hospital visits. Data from the Bureau of Labor Statistics were used to estimate the costs of lost productivity; data on age at death, life expectancy and economic valuations for a statistical life year were used to estimate the costs of a premature death. An estimated 10,674 (95% CI 8,661–12,687) VA ED visits, 2,538 (95% CI 2,112–2,964) VA hospitalizations, 5,522 (95% CI 4,834–6,210) all-cause deaths, and 3,793 (95% CI 3,375–4,211) underlying respiratory or circulatory deaths (inside and outside VA) among adult Veterans were attributable to influenza each year from 2010 through 2014. The annual value of lost productivity amounted to $27 (95% CI $24–31) million and the annual costs for ED visits were $6.2 (95% CI $5.1–7.4) million. Ninety-six percent of VA hospitalizations resulted in either death or a discharge to home, with annual costs

  6. Plant-associated bacterial populations on native and invasive plant species: comparisons between 2 freshwater environments.

    PubMed

    Olapade, Ola A; Pung, Kayleigh

    2012-06-01

    Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus.

  7. ISSR and AFLP analysis of the temporal and spatial population structure of the post-fire annual, Nicotiana attenuata, in SW Utah

    PubMed Central

    Bahulikar, Rahul A; Stanculescu, Dominic; Preston, Catherine A; Baldwin, Ian T

    2004-01-01

    Background The native annual tobacco, Nicotiana attenuata, is found primarily in large ephemeral populations (typically for less than 3 growing seasons) after fires in sagebrush and pinyon-juniper ecosystems and in small persistent populations (for many growing seasons) in isolated washes typically along roadsides throughout the Great Basin Desert of the SW USA. This distribution pattern is due to its unusual germination behavior. Ephemeral populations are produced by the germination of dormant seeds from long-lived seed banks which are stimulated to germinate by a combination of unidentified positive cues found in wood smoke and the removal of inhibitors leached from the unburned litter of the dominant vegetation. Persistent populations may result where these inhibitors do not exist, as in washes or along disturbed roadsides. To determine if this germination behavior has influenced population structure, we conducted an AFLP (244 individuals), ISSR (175 individuals) and ISSR+ AFLP (175 individuals) analysis on plants originating from seed collected from populations growing in 11 wash and burns over 11 years from the SW USA. Results Genetic variance as measured by both ISSR and AFLP markers was low among sites and comparatively higher within populations. Cluster analysis of the Utah samples with samples collected from Arizona, California, and Oregon as out-groups also did not reveal patterns. AMOVA analysis of the combined AFLP and ISSR data sets yielded significantly low genetic differentiation among sites (Φct), moderate among populations within sites (Φsc) and higher genetic differentiation within populations (Φst). Conclusions We conclude that the seed dormancy of this post-fire annual and its resulting age structure in conjunction with natural selection processes are responsible for significantly low among sites and comparatively high within-population genetic variation observed in this species. PMID:15350209

  8. Soil microbes and plant invasions—how soil-borne pathogens regulate plant populations and affect plant invasions

    USDA-ARS?s Scientific Manuscript database

    Exotic plant invaders are a major global threat to biodiversity and ecosystem function. Here I present multiple lines of evidence suggesting that soil microbial communities affect the population growth rates of Prunus serotina in its native range and affect its invasiveness abroad. Research often ...

  9. Grazing maintains native plant diversity and promotes community stability in an annual grassland.

    PubMed

    Beck, Jared J; Hernández, Daniel L; Pasari, Jae R; Zavaleta, Erika S

    2015-07-01

    Maintaining native biodiversity in grasslands requires management and mitigation of anthropogenic changes that have altered resource availability, grazing regimes, and community composition. In California (USA), high levels of atmospheric nitrogen (N) deposition have facilitated the invasion of exotic grasses, posing a threat to the diverse plant and insect communities endemic to serpentine grasslands. Cattle grazing has been employed to mitigate the consequences of exotic grass invasion, but the ecological effects of grazing in this system are not fully understood. To characterize the effects of realistic N deposition on serpentine plant communities and to evaluate the efficacy of grazing as a management tool, we performed a factorial experiment adding N and excluding large herbivores in California's largest serpentine grassland. Although we observed significant interannual variation in community composition related to climate in our six-year study, exotic cover was consistently and negatively correlated with native plant richness. Sustained low-level N addition did not influence plant community composition, but grazing reduced grass abundance while maintaining greater native forb cover, native plant diversity, and species richness in comparison to plots excluding large herbivores. Furthermore, grazing increased the temporal stability of plant communities by decreasing year-to-year variation in native forb cover, native plant diversity, and native species richness. Taken together, our findings demonstrate that moderate-intensity cattle grazing can be used to restrict the invasive potential of exotic grasses and maintain native plant communities in serpentine grasslands. We hypothesize that the reduced temporal variability in serpentine plant communities managed by grazing may directly benefit populations of the threatened Edith's Bay checkerspot butterfly (Euphydryas editha bayensis).

  10. SEASONALITY OF ANNUAL PLANT ESTABLISHMENT INFLUENCES THE INTERACTIONBETWEEN THE NON-NATIVE ANNUAL GRASS BROMUS MADRITENSIS SSP. RUBENS AND MOJAVE DESERT PERENNIALS

    SciTech Connect

    L A. DEFALCO; G. C. FERNANDEZ; R. S. NOWAK

    2004-01-01

    Competition between native and non-native species can change the composition and structure of plant communities, but in deserts the timing of non-native plant establishment can modulate their impacts to native species. In a field experiment, we varied densities of the non-native annual grass Bromus madritensis ssp. rubens around individuals of three native perennials--Larrea iridentata, Achnatherum hymenoides, and Pleuraphis rigida--in either winter or spring. Additional plots were prepared for the Same perennial species and seasons, but with a mixture of native annual species. Relative growth rates of perennial shoots (RGRs) declined with increasing Bromus biomass when Bromus that was established in winter had 2-3 mo of growth and high water use before perennial growth began. However, this high water use did not significantly reduce water potentials for the perennials, suggesting Bromus that established earlier depleted other soil resources, such as N, otherwise used by perennial plants. Spring-established Bromus had low biomass even at higher densities and did not effectively reduce RGRs, resulting in an overall lower impact to perennials than when Bromus was established in winter. Similarly, growth and reproduction of perennials with mixed annuals as neighbors did not differ from those with Bromus neighbors of equivalent biomass, but densities of these annuals did not support the high biomass necessary to reduce perennial growth. Thus, impacts of native Mojave Desert annuals to perennials are expected to be lower than those of Bromus because seed dormancy and narrow requirements for seedling survivorship produce densities and biomass lower than those achieved by Bromus. In comparing the effects of Bromus among perennial species, the impact of increased Bromus biomass on RGR was lower for Larrea than for the two perennial grasses, probably because Lurrea maintains low growth rates throughout the year, even after Bromus has completed its life cycle. This contrasts

  11. Effect of ultraviolet radiation on chlorophyll, carotenoid, protein and proline contents of some annual desert plants.

    PubMed

    Salama, Hediat M H; Al Watban, Ahlam A; Al-Fughom, Anoud T

    2011-01-01

    Investigation was carried out to find whether enhanced ultraviolet radiation influences the Malva parviflora L., Plantago major L., Rumex vesicarius L. and Sismbrium erysimoids Desf. of some annual desert plants. The seeds were grown in plastic pots equally filled with a pre-sieved normal sandy soil for 1 month. The planted pots from each species were randomly divided into equal groups (three groups). Plants of the first group exposed to white-light tubes (400-700 nm) 60 w and UV (365 nm) 8 w tubes. The second group was exposed to white-light tubes (400-700 nm) 60 w and UV (302 nm) 8 w tubes. The third group was exposed to white-light tubes (400-700 nm) 60 w and UV (254 nm) 8 w tubes, respectively, for six days. The results indicated that the chlorophyll contents were affected by enhanced UV radiation. The chlorophyll a, b, and total contents were decreased compared with the control values and reduced with the enhanced UV radiation, but the carotenoid was increased compared with the control and also reduced with the enhanced UV radiation. So, the contents of chlorophylls varied considerably. M. parviflora showed the highest constitutive levels of accumulated chlorophyll a, b, and total chlorophyll (0.463, 0.307 and 0.774 mg g(-1) f w) among the investigated plant species. P. major showed the lowest constitutive levels of the chloroplast pigments, 0.0036, 0.0038 and 0.0075 mg g(-1) f w for chlorophyll a, b, and total chlorophyll at UV-365 nm, respectively. The protein content was decreased significantly in both root and shoot systems compared with the control values but, it was increased with increasing wave lengths of UV-radiation of all tested plants. R. vesicarius showed the highest protein contents among the investigated plants; its content was 3.8 mg g(-1) f w at UV-365 nm in shoot system. On the other hand, decreasing ultraviolet wave length induced a highly significant increase in the level of proline in both root and shoot of all

  12. Constrained growth flips the direction of optimal phenological responses among annual plants.

    PubMed

    Lindh, Magnus; Johansson, Jacob; Bolmgren, Kjell; Lundström, Niklas L P; Brännström, Åke; Jonzén, Niclas

    2016-03-01

    Phenological changes among plants due to climate change are well documented, but often hard to interpret. In order to assess the adaptive value of observed changes, we study how annual plants with and without growth constraints should optimize their flowering time when productivity and season length changes. We consider growth constraints that depend on the plant's vegetative mass: self-shading, costs for nonphotosynthetic structural tissue and sibling competition. We derive the optimal flowering time from a dynamic energy allocation model using optimal control theory. We prove that an immediate switch (bang-bang control) from vegetative to reproductive growth is optimal with constrained growth and constant mortality. Increasing mean productivity, while keeping season length constant and growth unconstrained, delayed the optimal flowering time. When growth was constrained and productivity was relatively high, the optimal flowering time advanced instead. When the growth season was extended equally at both ends, the optimal flowering time was advanced under constrained growth and delayed under unconstrained growth. Our results suggests that growth constraints are key factors to consider when interpreting phenological flowering responses. It can help to explain phenological patterns along productivity gradients, and links empirical observations made on calendar scales with life-history theory.

  13. Aerial and soil seed banks enable populations of an annual species to cope with an unpredictable dune ecosystem.

    PubMed

    Gao, Ruiru; Yang, Xuejun; Yang, Fan; Wei, Lingling; Huang, Zhenying; Walck, Jeffrey L

    2014-08-01

    Simultaneous formation of aerial and soil seed banks by a species provides a mechanism for population maintenance in unpredictable environments. Eolian activity greatly affects growth and regeneration of plants in a sand dune system, but we know little about the difference in the contributions of these two seed banks to population dynamics in sand dunes. Seed release, germination, seedling emergence and survival of a desert annual, Agriophyllum squarrosum (Chenopodiaceae), inhabiting the Ordos Sandland in China, were determined in order to explore the different functions of the aerial and soil seed banks. The size of the aerial seed bank was higher than that of the soil seed bank throughout the growing season. Seed release was positively related to wind velocity. Compared with the soil seed bank, seed germination from the aerial seed bank was lower at low temperature (5/15 °C night/day) but higher in the light. Seedling emergence from the soil seed bank was earlier than that from the aerial seed bank. Early-emerged (15 April-15 May) seedlings died due to frost, but seedlings that emerged during the following months survived to reproduce successfully. The timing of seed release and different germination behaviour resulted in a temporal heterogeneity of seedling emergence and establishment between the two seed banks. The study suggests that a bet-hedging strategy for the two seed banks enables A. squarrosum populations to cope successfully with the unpredictable desert environment. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Density-dependent regulation of the sex ratio in an annual plant.

    PubMed

    Dorken, Marcel E; Pannell, John R

    2008-06-01

    Sex ratios are subject to strong frequency-dependent selection regulated by the mating system and the relative male versus female investment. In androdioecious plant populations, where males co-occur with hermaphrodites, the sex ratio depends on the rate of self-fertilization by hermaphrodites and on the relative pollen production of males versus hermaphrodites. Here, we report evolutionary changes in the sex ratio from experimental mating arrays of the androdioecious plant Mercurialis annua. We found that the progeny sex ratio depended strongly on density, with fewer males in the progeny of plants grown under low density. This occurred in part because of a plastic adjustment in pollen production by hermaphrodites, which produced more pollen when grown at low density than at high density. Our results provide support for the prediction that environmental conditions govern sex ratios through their effects on the relative fertility of unisexual versus hermaphrodite individuals.

  15. The Influence of Precipitation-Driven Annual Plant Growth on Dust Emission in the Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Urban, F. E.; Reynolds, R. L.; Fulton, R. E.

    2009-12-01

    Sparsely vegetated drylands are an important source for dust emission. However, little detail is known about dust generation in response to timing of precipitation and the consequent effects on soil and vegetation dynamics in these settings. This deficiency is especially acute at intermediate landscape scales, tens of meters to several hundred meters. It is essential to consider dust emission at this scale, because it links dust generation at scales of grains and wind tunnels with regional-scale dust examined using remotely sensed data from satellites. Three sites of slightly different geomorphic settings in the vicinity of Soda (dry) Lake were instrumented (in 1999) with meteorological and sediment transport sensors to measure wind erosion through saltating particle detection during high winds. Changes in vegetation in close proximity to the instrumented sites were bi-annually documented through measurements of plant type, cover, and repeat photographic imagery. Whereas high wind events are the dominant driver of saltation and dust emission, emissive conditions prevail only when annual plants are sparse or absent. Results show that wind erosion and dust emission at two study sites are highly variable and that such variability is dominantly related to vegetation type and cover as influenced by the amount and timing of antecedent precipitation. Secondary controls on dust emission are availability of new sediment related to flood deposits at the sites and seasonally differential wind strength. At sites where annual plants respond quickly and advantageously to precipitation, emissive conditions typically shut down because of vegetation growth within two to three months. This cover of annual plants, even when dead, persists in the desert landscape as a stabilizing agent for varying amounts of time, ten months to three years depending on the amount and vegetation type and subsequent input of precipitation and further annual plant growth. The lasting stabilization effect

  16. Population dynamics in central and edge populations of a narrowly endemic plant.

    PubMed

    Aikens, Melissa L; Roach, Deborah A

    2014-07-01

    Species' range limits can be caused by environmental gradients, and in such cases, abundance is thought to be highest in the center of a species range and decline towards the edge (the abundant-center model). Although in theory decreased abundance is caused by a decline in performance at the edge, it has been shown that performance and abundance are not necessarily related. Few studies have compared abundance and performance in center and edge populations of endemic species, whose ranges may be restricted by the availability of specialized habitat rather than environmental gradients across their range. Additionally, range-wide studies that examine both northern and southern edge populations are rare. We used Roan Mountain rattlesnake-root (Prenanthes roanensis), a perennial plant endemic to the Southern Appalachians (USA), to compare abundance and performance between central populations and populations at the northern and southern edges of the range. To account for multiple fitness components across the life cycle, we measured performance of edge populations as vital-rate contributions to population growth rate compared to the center. Abundance did not decline at the range edge, but some vital-rate contributions were lower in edge populations compared to central populations. However, each edge population differed in which vital-rate contributions were lower compared to the center. Our results do not support the abundant-center model, and it appears that local factors are important in structuring the range of this endemic species. It is important to recognize that when implementing conservation or management plans, populations in close proximity may have substantial variation in demographic rates due to differences in the local environment.

  17. Evaluate Habitat Use and Population Dynamics of Lampreys in Cedar Creek, Annual Report 2002.

    SciTech Connect

    Pirtle, Jodi; Stone, Jennifer; Barndt, Scott

    2003-03-01

    Pacific lamprey (Lampetra tridentata) in the Columbia River basin have declined to a remnant of their pre-1940s populations and the status of the western brook lamprey (L. richardsoni) and river lamprey (L. ayresi) is unknown. Identifying the biological and ecological factors limiting lamprey populations is critical to their recovery, but little research has been conducted on these species within the Columbia River basin. This ongoing, multi-year study examines lamprey populations in Cedar Creek, Washington, a third-order tributary to the Lewis River. This annual report describes the activities and results of the third year of this project. Adult (n = 62), metamorphosed (n = 76), transforming (n = 4), and ammocoete (n = 315) stages of Pacific and western brook lamprey were examined in 2002. Lampreys were captured using adult fish ladders, lamprey pots, rotary screw traps, and lamprey electrofishers. In addition, fifty-four spawning ground surveys were conducted during which 124 Pacific lamprey and 13 western brook lamprey nests were identified. Stream gradient of spawning grounds were surveyed to better understand spawning habitat requirements.

  18. Microevolutionary responses in experimental populations of plants to CO2-enriched environments: parallel results from two model systems.

    PubMed Central

    Bazzaz, F A; Jasieński, M; Thomas, S C; Wayne, P

    1995-01-01

    Despite the critical role that terrestrial vegetation plays in the Earth's carbon cycle, very little is known about the potential evolutionary responses of plants to anthropogenically induced increases in concentrations of atmospheric CO2. We present experimental evidence that rising CO2 concentration may have a direct impact on the genetic composition and diversity of plant populations but is unlikely to result in selection favoring genotypes that exhibit increased productivity in a CO2-enriched atmosphere. Experimental populations of an annual plant (Abutilon theophrasti, velvetleaf) and a temperate forest tree (Betula alleghaniensis, yellow birch) displayed responses to increased CO2 that were both strongly density-dependent and genotype-specific. In competitive stands, a higher concentration of CO2 resulted in pronounced shifts in genetic composition, even though overall CO2-induced productivity enhancements were small. For the annual species, quantitative estimates of response to selection under competition were 3 times higher at the elevated CO2 level. However, genotypes that displayed the highest growth responses to CO2 when grown in the absence of competition did not have the highest fitness in competitive stands. We suggest that increased CO2 intensified interplant competition and that selection favored genotypes with a greater ability to compete for resources other than CO2. Thus, while increased CO2 may enhance rates of selection in populations of competing plants, it is unlikely to result in the evolution of increased CO2 responsiveness or to operate as an important feedback in the global carbon cycle. However, the increased intensity of selection and drift driven by rising CO2 levels may have an impact on the genetic diversity in plant populations. Images Fig. 2 PMID:11607574

  19. Microevolutionary responses in experimental populations of plants to CO2-enriched environments: parallel results from two model systems.

    PubMed

    Bazzaz, F A; Jasieński, M; Thomas, S C; Wayne, P

    1995-08-29

    Despite the critical role that terrestrial vegetation plays in the Earth's carbon cycle, very little is known about the potential evolutionary responses of plants to anthropogenically induced increases in concentrations of atmospheric CO2. We present experimental evidence that rising CO2 concentration may have a direct impact on the genetic composition and diversity of plant populations but is unlikely to result in selection favoring genotypes that exhibit increased productivity in a CO2-enriched atmosphere. Experimental populations of an annual plant (Abutilon theophrasti, velvetleaf) and a temperate forest tree (Betula alleghaniensis, yellow birch) displayed responses to increased CO2 that were both strongly density-dependent and genotype-specific. In competitive stands, a higher concentration of CO2 resulted in pronounced shifts in genetic composition, even though overall CO2-induced productivity enhancements were small. For the annual species, quantitative estimates of response to selection under competition were 3 times higher at the elevated CO2 level. However, genotypes that displayed the highest growth responses to CO2 when grown in the absence of competition did not have the highest fitness in competitive stands. We suggest that increased CO2 intensified interplant competition and that selection favored genotypes with a greater ability to compete for resources other than CO2. Thus, while increased CO2 may enhance rates of selection in populations of competing plants, it is unlikely to result in the evolution of increased CO2 responsiveness or to operate as an important feedback in the global carbon cycle. However, the increased intensity of selection and drift driven by rising CO2 levels may have an impact on the genetic diversity in plant populations.

  20. Reduced pollinator service and elevated pollen limitation at the geographic range limit of an annual plant.

    PubMed

    Moeller, David A; Geber, Monica A; Eckhart, Vincent M; Tiffin, Peter

    2012-05-01

    Mutualisms are well known to influence individual fitness and the population dynamics of partner species, but little is known about whether they influence species distributions and the location of geographic range limits. Here, we examine the contribution of plant-pollinator interactions to the geographic range limit of the California endemic plant Clarkia xantiana ssp. xantiana. We show that pollinator availability declined from the center to the margin of the geographic range consistently across four years of study. This decline in pollinator availability was caused to a greater extent by variation in the abundance of generalist rather than specialist bee pollinators. Climate data suggest that patterns of precipitation in the current and previous year drove variation in bee abundance because of its effects on cues for bee emergence in the current year and the abundance of floral resources in the previous year. Experimental floral manipulations showed that marginal populations had greater outcross pollen limitation of reproduction, in parallel with the decline in pollinator abundance. Although plants are self-compatible, we found no evidence that autonomous selfing contributes to reproduction, and thus no evidence that it alleviates outcross pollen limitation in marginal populations. Furthermore, we found no association between the distance to the range edge and selfing rate, as estimated from sequence and microsatellite variation, indicating that the mating system has not evolved in response to the pollination environment at the range periphery. Overall, our results suggest that dependence on pollinators for reproduction may be an important constraint limiting range expansion in this system.

  1. Population viability analysis of plant and animal populations with stochastic integral projection models.

    PubMed

    Jaffré, Malo; Le Galliard, Jean-François

    2016-12-01

    Integral projection models (IPM) make it possible to study populations structured by continuous traits. Recently, Vindenes et al. (Ecology 92:1146-1156, 2011) proposed an extended IPM to analyse the dynamics of small populations in stochastic environments, but this model has not yet been used to conduct population viability analyses. Here, we used the extended IPM to analyse the stochastic dynamics of IPM of small size-structured populations in one plant and one animal species (evening primrose and common lizard) including demographic stochasticity in both cases and environmental stochasticity in the lizard model. We also tested the accuracy of a diffusion approximation of the IPM for the two empirical systems. In both species, the elasticity for λ was higher with respect to parameters linked to body growth and size-dependent reproduction rather than survival. An analytical approach made it possible to quantify demographic and environmental variance to calculate the average stochastic growth rate. Demographic variance was further decomposed to gain insights into the most important size classes and demographic components. A diffusion approximation provided a remarkable fit to the stochastic dynamics and cumulative extinction risk, except for very small populations where stochastic growth rate was biased upward or downward depending on the model. These results confirm that the extended IPM provides a powerful tool to assess the conservation status and compare the stochastic demography of size-structured species, but should be complemented with individual based models to obtain unbiased estimates for very small populations of conservation concern.

  2. Climate change alters reproductive isolation and potential gene flow in an annual plant

    PubMed Central

    Franks, Steven J; Weis, Arthur E

    2009-01-01

    Climate change will likely cause evolution due not only to selection but also to changes in reproductive isolation within and among populations. We examined the effects of a natural drought on the timing of flowering in two populations of Brassica rapa and the consequences for predicted reproductive isolation and potential gene flow. Seeds were collected before and after a 5-year drought in southern California from two populations varying in soil moisture. Lines derived from these seeds were raised in the greenhouse under wet and drought conditions. We found that the natural drought caused changes in reproductive timing and that the changes were greater for plants from the wet than from the dry site. This differential shift caused the populations to become more phenological similar, which should lead to less reproductive isolation and increased gene flow. We estimated a high level of assortative mating by flowering time, which potentially contributed to the rapid evolution of phenological traits following the drought. Estimates of assortative mating were higher for the wet site population, and assortative mating was reduced following the drought. This study shows that climate change can potentially alter gene flow and reproductive isolation within and among populations, strongly influencing evolution. PMID:25567893

  3. Energy consumption and expenditure projections by population group on the basis of the annual energy outlook 1999 forecast

    SciTech Connect

    Poyer, D.A.; Balsley, J.H.

    2000-01-07

    This report presents an analysis of the relative impact of the base-case scenario used in Annual Energy Outlook 1999 on different population groups. Projections of energy consumption and expenditures, as well as energy expenditure as a share of income, from 1996 to 2020 are given. The projected consumption of electricty, natural gas, distillate fuel, and liquefied petroleum gas during this period is also reported for each population group. In addition, this report compares the findings of the Annual Energy Outlook 1999 report with the 1998 report. Changes in certain indicators and information affect energy use forecasts, and these effects are analyzed and discussed.

  4. Aquatic Plant Control Research Program. Proceedings, Annual Meeting, Aquatic Plant Control Research Program (23rd) Held in West Palm Beach, Florida on 14-17 November 1988

    DTIC Science & Technology

    1989-06-01

    plants in the treatment area. One potential alternative to current aquatic weed control strategies is to alter natural plant hormonal processes and...the process of selecting a treatment technique for application. Some example questions are (a) When will this particular aquatic plant population reach...toward the water surface. This process continues until *University of Southern Mississippi, Department of Biological Sciences, Hattiesburg

  5. Aquatic environmental conditions in Chickamauga Reservoir during operation of Sequoyah Nuclear Plant: Fifth annual report (1985)

    SciTech Connect

    Beard, L.M.; Bruggink, D.J.; Buchanan, J.P.; Buckingham, R.A.; Dycus, D.L.; Mulkey, C.E.; Smith, A.O.; Swor, C.T.; Tomljanovich, D.A.; Wade, D.C.

    1986-08-01

    TVA is required by its National Pollutant Discharge Elimination System (NPDES) Permit for Sequoyah Nuclear Plant (SQN) to conduct and report annually on operational nonradiological monitoring to evaluate potential effects of SQN on Chickamauga Reservoir. Because few changes were identified through 1984, the following changes were recommended in June 1985: (1) terminate studies on benthic macroinvertebrates, mollusk bioaccumulation, fish impingement, fish gill netting, fish creel surveys, and water quality at the plant intake and discharge; (2) continue studies on plankton and larval fish with specific changes; and (3) continue cove rotenone studies without change. These recommendations were instituted in July 1985 following approval from the Environmental Protection Agency (EPA). This report evaluates 1985 results for the continued portions and, briefly, for the discontinued portions conducted prior to EPA's approval. Evaluation of water quality data showed that during low flows SQN altered the distribution of DO in the water column at and downstream of the diffusers. Studies to define the extent and duration of the DO alteration will be conducted during spring and summer when SQN resumes operation.

  6. Projecting pest population dynamics under global warming: the combined effect of inter- and intra-annual variations.

    PubMed

    Zidon, Royi; Tsueda, Hirotsugu; Morin, Efrat; Morin, Shai

    2016-06-01

    The typical short generation length of insects makes their population dynamics highly sensitive not only to mean annual temperatures but also to their intra-annual variations. To consider the combined effect of both thermal factors under global warming, we propose a modeling framework that links general circulation models (GCMs) with a stochastic weather generator and population dynamics models to predict species population responses to inter- and intra-annual temperature changes. This framework was utilized to explore future changes in populations of Bemisia tabaci, an invasive insect pest-species that affects multiple agricultural systems in the Mediterranean region. We considered three locations representing different pest status and climatic conditions: Montpellier (France), Seville (Spain), and Beit-Jamal (Israel). We produced ensembles of local daily temperature realizations representing current and future (mid-21st century) climatic conditions under two emission scenarios for the three locations. Our simulations predicted a significant increase in the average number of annual generations and in population size, and a significant lengthening of the growing season in all three locations. A negative effect was found only in Seville for the summer season, where future temperatures lead to a reduction in population size. High variability in population size was observed between years with similar annual mean temperatures, suggesting a strong effect of intra-annual temperature variation. Critical periods were from late spring to late summer in Montpellier and from late winter to early summer in Seville and Beit-Jamal. Although our analysis suggested that earlier seasonal activity does not necessarily lead to increased populations load unless an additional generation is produced, it is highly likely that the insect will become a significant pest of open-fields at Mediterranean latitudes above 40° during the next 50 years. Our simulations also implied that current

  7. Aquatic Plant Control Research Program: Proceedings Annual Meeting (28th) Held in Baltimore, Maryland on November 15-18, 1993

    DTIC Science & Technology

    1994-06-01

    Proceedngs, 28th Annual Meeting, APCRP Bennett 175 Obilogic Caotr" Tecnology Quarantine Research by R. Buckinghamt Introduction Our quarantine program...waterproof hedge cutters. The resulting tanae (Table 1), releases have been more than plant material was placed into plastic garbage adequate in many

  8. Annual cycle of energy and time expenditure in a golden-mantled ground squirrel population.

    PubMed

    Kenagy, G J; Sharbaugh, S M; Nagy, K A

    1989-02-01

    We have analyzed seasonal shifts of energy and time allocation in a population of golden-mantled ground squirrels (Spermophilus saturatus) by directly measuring total daily energy expenditure (DEE) with an isotopic technique ("doubly labeled water"=dlw), and by estimating components of total DEE through an integration of field behavioral observations with laboratory-measured rates of energy expenditure (oxygen consumption) associated with major behavioral and physiological states. Hibernation laster about 7 1/2 months, and the 4 1/2-month activity season consisted of mating, a 28-d gestation of 3-5 young, 5 1/2 weeks of postnatal growth building to a peak in lactation just before the young emerged above ground, an additional 2-3-week period of maternal care before dispersal, and finally restoration of body mass preceding hibernation. Although the hibernation season comprised nearly two-thirds of the year, it involved only 13-17% of annual energy expenditure, leaving about 85% of energy expenditure for the active season. Ground squirrels were actually present on the surface for only about 11% of the year's time, and the foraging time required to obtain the total annual energy supply amounted to only about 2% of the year's time. The squirrels fed mainly on herbs in the early season and hypogeous fungi later; both were used extensively during peak lactation when female energy expenditure and demand were maximal. Average daily foraging time increased steadily throughout the season to a maximum of 28% of aboveground time as availability of greens diminished and fungus predominated in the diet; time availability did not limit foraging since the animals sat on average for 65% of the daily surface time of about 7 h. Timing of reproduction is apparently optimized such that peak reproductive energy demands are matched with maximal food availability and moderate thermal conditions that minimize energy demand. Despite the greater body mass of males, the greatest total DEE

  9. Molecular insights into seed dispersal mutualisms driving plant population recruitment

    NASA Astrophysics Data System (ADS)

    García, Cristina; Grivet, Delphine

    2011-11-01

    Most plant species require mutualistic interactions with animals to fulfil their demographic cycle. In this regard frugivory (i.e., the intake of fruits by animals) enhances natural regeneration by mobilizing a large amount of seeds from source trees to deposition sites across the landscape. By doing so, frugivores move propagules, and the genotypes they harbour creating the spatial, ecological, and genetic environment under which subsequent recruitment proceeds. Recruitment patterns can be envisioned as the result of two density- and distance-dependent processes: seed dispersal and seed/seedling survival (the Janzen-Connell model). Population genetic studies add another layer of complexity for understanding the fate of dispersed propagules: the genetic relatedness among neighbouring seeds within a seed clump, a major outcome of frugivore activity, modifies their chances of germinating and surviving. Yet, we virtually ignore how the spatial distribution of maternal progenies and recruitment patterns relate with each other in frugivore-generated seed rains. Here we focus on the critical role of frugivore-mediated seed dispersal in shaping the spatial distribution of maternal progenies in the seed rain. We first examine which genetic mechanisms underlying recruitment are influenced by the spatial distribution of maternal progenies. Next, we examine those studies depicting the spatial distribution of maternal progenies in a frugivore-generated seed rain. In doing so, we briefly review the most suitable analytical approaches applied to track the contribution of fruiting trees to the seed rain based on molecular data. Then we look more specifically at the role of distinct frugivore guilds in determining maternal genetic correlations and their expected consequences for recruitment patterns. Finally we posit some general conclusions and suggest future research directions that would provide a more comprehensive understanding of the ecological and evolutionary consequences

  10. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  11. 40 CFR 230.75 - Actions affecting plant and animal populations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Actions affecting plant and animal... Actions To Minimize Adverse Effects § 230.75 Actions affecting plant and animal populations. Minimization of adverse effects on populations of plants and animals can be achieved by: (a) Avoiding changes...

  12. Genecological approaches to predicting the effects of climate change on plant populations

    Treesearch

    Francis F. Kilkenny

    2015-01-01

    Climate change threatens native plant populations and plant communities globally. It is critical that land managers have a clear understanding of climate change impacts on plant species and populations so that restoration efforts can be adjusted accordingly. This paper reviews the develop.ment and use of seed transfer guidelines for restoration in the face of global...

  13. Population structure of a vector-borne plant parasite.

    PubMed

    Yule, Kelsey M; Koop, Jennifer A H; Alexandre, Nicolas M; Johnston, Lauren R; Whiteman, Noah K

    2016-07-01

    Parasites are among the most diverse groups of life on Earth, yet complex natural histories often preclude studies of their speciation processes. The biology of parasitic plants facilitates in situ collection of data on both genetic structure and the mechanisms responsible for that structure. Here, we studied the role of mating, dispersal and establishment in host race formation of a parasitic plant. We investigated the population genetics of a vector-borne desert mistletoe (Phoradendron californicum) across two legume host tree species (Senegalia greggii and Prosopis velutina) in the Sonoran desert using microsatellites. Consistent with host race formation, we found strong host-associated genetic structure in sympatry, little genetic variation due to geographic site and weak isolation by distance. We hypothesize that genetic differentiation results from differences in the timing of mistletoe flowering by host species, as we found initial flowering date of individual mistletoes correlated with genetic ancestry. Hybrids with intermediate ancestry were detected genetically. Individuals likely resulting from recent, successful establishment events following dispersal between the host species were detected at frequencies similar to hybrids between host races. Therefore, barriers to gene flow between the host races may have been stronger at mating than at dispersal. We also found higher inbreeding and within-host individual relatedness values for mistletoes on the more rare and isolated host species (S. greggii). Our study spanned spatial scales to address how interactions with both vectors and hosts influence parasitic plant structure with implications for parasite virulence evolution and speciation. © 2016 John Wiley & Sons Ltd.

  14. Effect of crop development on biogenic emissions from plant populations grown in closed plant growth chambers

    NASA Technical Reports Server (NTRS)

    Batten, J. H.; Stutte, G. W.; Wheeler, R. M.

    1995-01-01

    The Biomass Production Chamber at John F. Kennedy Space Center is a closed plant growth chamber facility that can be used to monitor the level of biogenic emissions from large populations of plants throughout their entire growth cycle. The head space atmosphere of a 26-day-old lettuce (Lactuca sativa cv. Waldmann's Green) stand was repeatedly sampled and emissions identified and quantified using GC-mass spectrometry. Concentrations of dimethyl sulphide, carbon disulphide, alpha-pinene, furan and 2-methylfuran were not significantly different throughout the day; whereas, isoprene showed significant differences in concentration between samples collected in light and dark periods. Volatile organic compounds from the atmosphere of wheat (Triticum aestivum cv. Yecora Rojo) were analysed and quantified from planting to maturity. Volatile plant-derived compounds included 1-butanol, 2-ethyl-1-hexanol, nonanal, benzaldehyde, tetramethylurea, tetramethylthiourea, 2-methylfuran and 3-methylfuran. Concentrations of volatiles were determined during seedling establishment, vegetative growth, anthesis, grain fill and senescence and found to vary depending on the developmental stage. Atmospheric concentrations of benzaldehyde and nonanal were highest during anthesis, 2-methylfuran and 3-methylfuran concentrations were greatest during grain fill, and the concentration of the tetramethylurea peaked during senescence.

  15. Genetic consequences of habitat fragmentation in plant populations: susceptible signals in plant traits and methodological approaches.

    PubMed

    Aguilar, Ramiro; Quesada, Mauricio; Ashworth, Lorena; Herrerias-Diego, Yvonne; Lobo, Jorge

    2008-12-01

    Conservation of genetic diversity, one of the three main forms of biodiversity, is a fundamental concern in conservation biology as it provides the raw material for evolutionary change and thus the potential to adapt to changing environments. By means of meta-analyses, we tested the generality of the hypotheses that habitat fragmentation affects genetic diversity of plant populations and that certain life history and ecological traits of plants can determine differential susceptibility to genetic erosion in fragmented habitats. Additionally, we assessed whether certain methodological approaches used by authors influence the ability to detect fragmentation effects on plant genetic diversity. We found overall large and negative effects of fragmentation on genetic diversity and outcrossing rates but no effects on inbreeding coefficients. Significant increases in inbreeding coefficient in fragmented habitats were only observed in studies analyzing progenies. The mating system and the rarity status of plants explained the highest proportion of variation in the effect sizes among species. The age of the fragment was also decisive in explaining variability among effect sizes: the larger the number of generations elapsed in fragmentation conditions, the larger the negative magnitude of effect sizes on heterozygosity. Our results also suggest that fragmentation is shifting mating patterns towards increased selfing. We conclude that current conservation efforts in fragmented habitats should be focused on common or recently rare species and mainly outcrossing species and outline important issues that need to be addressed in future research on this area.

  16. Effect of crop development on biogenic emissions from plant populations grown in closed plant growth chambers

    NASA Technical Reports Server (NTRS)

    Batten, J. H.; Stutte, G. W.; Wheeler, R. M.

    1995-01-01

    The Biomass Production Chamber at John F. Kennedy Space Center is a closed plant growth chamber facility that can be used to monitor the level of biogenic emissions from large populations of plants throughout their entire growth cycle. The head space atmosphere of a 26-day-old lettuce (Lactuca sativa cv. Waldmann's Green) stand was repeatedly sampled and emissions identified and quantified using GC-mass spectrometry. Concentrations of dimethyl sulphide, carbon disulphide, alpha-pinene, furan and 2-methylfuran were not significantly different throughout the day; whereas, isoprene showed significant differences in concentration between samples collected in light and dark periods. Volatile organic compounds from the atmosphere of wheat (Triticum aestivum cv. Yecora Rojo) were analysed and quantified from planting to maturity. Volatile plant-derived compounds included 1-butanol, 2-ethyl-1-hexanol, nonanal, benzaldehyde, tetramethylurea, tetramethylthiourea, 2-methylfuran and 3-methylfuran. Concentrations of volatiles were determined during seedling establishment, vegetative growth, anthesis, grain fill and senescence and found to vary depending on the developmental stage. Atmospheric concentrations of benzaldehyde and nonanal were highest during anthesis, 2-methylfuran and 3-methylfuran concentrations were greatest during grain fill, and the concentration of the tetramethylurea peaked during senescence.

  17. The contribution of germination functional traits to population dynamics of a desert plant community.

    PubMed

    Huang, Zhenying; Liu, Shuangshuang; Bradford, Kent J; Huxman, Travis E; Venable, D Lawrence

    2016-01-01

    Early life-cycle events play critical roles in determining the population and community dynamics of plants. The ecology of seeds and their germination patterns can determine range limits, adaptation to environmental variation, species diversity, and community responses to climate change. Understanding the adaptive consequences and environmental filtering of such functional traits will allow us to explain and predict ecological dynamics. Here we quantify key functional aspects of germination physiology and relate them to an existing functional ecology framework to explain long-term population dynamics for 13 species of desert annuals near Tucson, Arizona, USA. Our goal was to assess the extent to which germination functional biology contributes to long-term population processes in nature. Some of the species differences in base, optimum, and maximum temperatures for germination, thermal times to germination, and base water potentials for germination were strongly related to 20-yr mean germination fractions, 25-yr average germination dates, seed size, and long-term demographic variation. Comparisons of germination fraction, survival, and fecundity vs. yearly changes in population size found significant roles for all three factors, although in varying proportions for different species. Relationships between species' germination physiologies and relative germination fractions varied across years, with fast-germinating species being favored in years with warm temperatures during rainfall events in the germination season. Species with low germination fractions and high demographic variance have low integrated water-use efficiency, higher vegetative growth rates, and smaller, slower-germinating seeds. We have identified and quantified a number of functional traits associated with germination biology that play critical roles in ecological population dynamics.

  18. Inter-annual changes in detritus-based food chains can enhance plant growth response to elevated atmospheric CO2.

    PubMed

    Hines, Jes; Eisenhauer, Nico; Drake, Bert G

    2015-12-01

    Elevated atmospheric CO2 generally enhances plant growth, but the magnitude of the effects depend, in part, on nutrient availability and plant photosynthetic pathway. Due to their pivotal role in nutrient cycling, changes in abundance of detritivores could influence the effects of elevated atmospheric CO2 on essential ecosystem processes, such as decomposition and primary production. We conducted a field survey and a microcosm experiment to test the influence of changes in detritus-based food chains on litter mass loss and plant growth response to elevated atmospheric CO2 using two wetland plants: a C3 sedge (Scirpus olneyi) and a C4 grass (Spartina patens). Our field study revealed that organism's sensitivity to climate increased with trophic level resulting in strong inter-annual variation in detritus-based food chain length. Our microcosm experiment demonstrated that increased detritivore abundance could not only enhance decomposition rates, but also enhance plant growth of S. olneyi in elevated atmospheric CO2 conditions. In contrast, we found no evidence that changes in the detritus-based food chains influenced the growth of S. patens. Considered together, these results emphasize the importance of approaches that unite traditionally subdivided food web compartments and plant physiological processes to understand inter-annual variation in plant production response to elevated atmospheric CO2. © 2015 John Wiley & Sons Ltd.

  19. The presence of Bt-transgenic oilseed rape in wild mustard populations affects plant growth.

    PubMed

    Liu, Yongbo; Stewart, C Neal; Li, Junsheng; Huang, Hai; Zhang, Xitao

    2015-12-01

    The adventitious presence of transgenic plants in wild plant populations is of ecological and regulatory concern, but the consequences of adventitious presence are not well understood. Here, we introduced Bacillus thuringiensis Cry1Ac (Bt)-transgenic oilseed rape (Bt OSR, Brassica napus) with various frequencies into wild mustard (Brassica juncea) populations. We sought to better understand the adventitious presence of this transgenic insecticidal crop in a wild-relative plant population. We assessed the factors of competition, resource availability and diamondback moth (Plutella xylostella) infestation on plant population dynamics. As expected, Bt OSR performed better than wild mustard in mixed populations under herbivore attack in habitats with enough resources, whereas wild mustard had higher fitness when Bt OSR was rarer in habitats with limited resources. Results suggest that the presence of insect-resistant transgenic plants could decrease the growth of wild mustard and Bt OSR plants and their populations, especially under high herbivore pressure.

  20. Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years

    USGS Publications Warehouse

    Wann, Greg; Aldridge, Cameron L.; Braun, Clait E.

    2014-01-01

    Long-term datasets for high-elevation species are rare, and considerable uncertainty exists in understanding how high-elevation populations have responded to recent climate warming. We present estimates of demographic vital rates from a 43-year population study of white-tailed ptarmigan (Lagopus leucura), a species endemic to alpine habitats in western North America. We used capture-recapture models to estimate annual rates of apparent survival, population growth, and recruitment for breeding-age ptarmigan, and we fit winter weather covariates to models in an attempt to explain annual variation. There were no trends in survival over the study period but there was strong support for age and sex effects. The average rate of annual growth suggests a relatively stable breeding-age population ( λ ¯ = 1.036), but there was considerable variation between years for both population growth and recruitment rates. Winter weather covariates only explained a small amount of variation in female survival and were not an important predictor of male survival. Cumulative winter precipitation was found to have a quadratic effect on female survival, with survival being highest during years of average precipitation. Cumulative winter precipitation was positively correlated with population growth and recruitment rates, although this covariate only explained a small amount of annual variation in these rates and there was considerable uncertainty among the models tested. Our results provide evidence for an alpine-endemic population that has not experienced extirpation or drastic declines. However, more information is needed to understand risks and vulnerabilities of warming effects on juveniles as our analysis was confined to determination of vital rates for breeding-age birds.

  1. Population genetic structure of annual and perennial populations of Zostera marina L. along the Pacific coast of Baja California and the Gulf of California

    USGS Publications Warehouse

    Munoz-Salazar, R.; Talbot, S.L.; Sage, G.K.; Ward, D.H.; Cabello-Pasini, Alejandro

    2005-01-01

    The Baja California peninsula represents a biogeographical boundary contributing to regional differentiation among populations of marine animals. We investigated the genetic characteristics of perennial and annual populations of the marine angiosperm, Zostera marina, along the Pacific coast of Baja California and in the Gulf of California, respectively. Populations of Z. marina from five coastal lagoons along the Pacific coast and four sites in the Gulf of California were studied using nine microsatellite loci. Analyses of variance revealed significant interregional differentiation, but no subregional differentiation. Significant spatial differentiation, assessed using θ values, was observed among all populations within the two regions. Z. marina populations along the Pacific coast are separated by more than 220 km and had the greatest θ (0.13-0.28) values, suggesting restricted gene flow. In contrast, lower but still significant genetic differentiation was observed among populations within the Gulf of California (θ = 0.04-0.18), even though populations are separated by more than 250 km. This suggests higher levels of gene flow among Gulf of California populations relative to Pacific coast populations. Direction of gene flow was predominantly southward among Pacific coast populations, whereas no dominant polarity in the Gulf of California populations was observed. The test for isolation by distance (IBD) showed a significant correlation between genetic and geographical distances in Gulf of California populations, but not in Pacific coast populations, perhaps because of shifts in currents during El Nino Southern Oscillation (ENSO) events along the Pacific coast.

  2. Population genetic structure of annual and perennial populations of Zostera marina L. along the Pacific coast of Baja California and the Gulf of California.

    PubMed

    Muñiz-Salazar, Raquel; Talbot, Sandra L; Sage, George K; Ward, David H; Cabello-Pasini, Alejandro

    2005-03-01

    The Baja California peninsula represents a biogeographical boundary contributing to regional differentiation among populations of marine animals. We investigated the genetic characteristics of perennial and annual populations of the marine angiosperm, Zostera marina, along the Pacific coast of Baja California and in the Gulf of California, respectively. Populations of Z. marina from five coastal lagoons along the Pacific coast and four sites in the Gulf of California were studied using nine microsatellite loci. Analyses of variance revealed significant interregional differentiation, but no subregional differentiation. Significant spatial differentiation, assessed using theta(ST) values, was observed among all populations within the two regions. Z. marina populations along the Pacific coast are separated by more than 220 km and had the greatest theta(ST) (0.13-0.28) values, suggesting restricted gene flow. In contrast, lower but still significant genetic differentiation was observed among populations within the Gulf of California (theta(ST) = 0.04-0.18), even though populations are separated by more than 250 km. This suggests higher levels of gene flow among Gulf of California populations relative to Pacific coast populations. Direction of gene flow was predominantly southward among Pacific coast populations, whereas no dominant polarity in the Gulf of California populations was observed. The test for isolation by distance (IBD) showed a significant correlation between genetic and geographical distances in Gulf of California populations, but not in Pacific coast populations, perhaps because of shifts in currents during El Niño Southern Oscillation (ENSO) events along the Pacific coast.

  3. Annual survival rates of adult and immature eastern population tundra swans

    USGS Publications Warehouse

    Nichols, J.D.; Bart, J.; Limpert, R.J.; Sladen, William J. L.; Hines, J.E.

    1992-01-01

    Tundra swans (Cygnus columbianus ) of the eastern population were neckbanded in Maryland, North Carolina, and Alaska from 1966 through 1990. These swans were resighted and recaptured during autumn, winter, and spring, 1966-1990. Although the original motivation for this study involved swan movements, we wanted to use the resulting data to test hypotheses about sources of variation in swan survival rates. Recaptures of legbanded and neckbanded swans permitted us to estimate neckband loss rates, which were found to vary with age and sex of swans, and number of years since initial application. Estimates of annual neckband retention rate ranged from about 0.50 for adult male swans greater than or equal to 2 years after initial neckbanding to > 0.96 for immature swans and adult females the first year following neckbanding. This variation in neckband loss rates prevented the simple correction of survival estimates to account for such loss. Consequently, we developed a series of multinomial models parameterized with survival, sighting, and neckband retention probabilities for use with the recapture and resighting data.

  4. Ecotypic variation in growth responses to simulated herbivory: trade-off between maximum relative growth rate and tolerance to defoliation in an annual plant

    PubMed Central

    Camargo, Iván D.; Tapia-López, Rosalinda; Núñez-Farfán, Juan

    2015-01-01

    It has been hypothesized that slow-growing plants are more likely to maximize above-ground biomass and fitness when defoliated by herbivores than those with an already high relative growth rate (RGR). Some populations of the annual herb Datura stramonium L. can tolerate foliar damage better than others. The physiological basis of this difference is examined here in a comparative study of two ecotypes that differ in tolerance and maximum growth rate, using a growth analytical approach. One hundred and fifty-four plants of each ecotype grown under controlled conditions were suddenly defoliated (35 % of total leaf area removed) and a similar sample size of plants remained undefoliated (control). Ontogenetic plastic changes in RGR and its growth components [net assimilation rate (NAR), specific leaf area and leaf weight ratio (LWR)] after defoliation were measured to determine whether these plastic changes maximize plant growth and fitness. Different ontogenetic phases of the response were discerned and increased RGR of defoliated plants was detected at the end of the experimental period, but brought about by a different growth component (NAR or LWR) in each ecotype. These changes in RGR are putatively related to increases in fitness in defoliated environments. At the intra-specific scale, data showed a trade-off between the ability to grow under benign environmental conditions and the ability to tolerate resource limitation due to defoliation. PMID:25725085

  5. Seasonal timing of first rain storms affects rare plant population dynamics.

    PubMed

    Levine, Jonathan M; McEachern, A Kathryn; Cowan, Clark

    2011-12-01

    A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables.

  6. Seasonal timing of first rain storms affects rare plant population dynamics

    USGS Publications Warehouse

    Levine, J.M.; McEachern, A.K.; Cowan, C.

    2011-01-01

    A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables.

  7. Within and between population variation in plant traits predicts ecosystem functions associated with a dominant plant species

    PubMed Central

    Breza, Lauren C; Souza, Lara; Sanders, Nathan J; Classen, Aimée T

    2012-01-01

    Linking intraspecific variation in plant traits to ecosystem carbon uptake may allow us to better predict how shift in populations shape ecosystem function. We investigated whether plant populations of a dominant old-field plant species (Solidago altissima) differed in carbon dynamics and if variation in plant traits among genotypes and between populations predicted carbon dynamics. We established a common garden experiment with 35 genotypes from three populations of S. altissima from either Tennessee (southern populations) or Connecticut (northern populations) to ask whether: (1) southern and northern Solidago populations will differ in aboveground productivity, leaf area, flowering time and duration, and whole ecosystem carbon uptake, (2) intraspecific trait variation (growth and reproduction) will be related to intraspecific variation in gross ecosystem CO2 exchange (GEE) and net ecosystem CO2 exchange (NEE) within and between northern and southern populations. GEE and NEE were 4.8× and 2× greater in southern relative to northern populations. Moreover, southern populations produced 13× more aboveground biomass and 1.4× more inflorescence mass than did northern populations. Flowering dynamics (first- and last-day flowering and flowering duration) varied significantly among genotypes in both the southern and northern populations, but plant performance and ecosystem function did not. Both productivity and inflorescence mass predicted NEE and GEE between S. altissima southern and northern populations. Taken together, our data demonstrate that variation between S. altissima populations in performance and flowering traits are strong predictors of ecosystem function in a dominant old-field species and suggest that populations of the same species might differ substantially in their response to environmental perturbations. PMID:22833791

  8. Plant defences limit herbivore population growth by changing predator-prey interactions.

    PubMed

    Kersch-Becker, Mônica F; Kessler, André; Thaler, Jennifer S

    2017-09-13

    Plant quality and predators are important factors affecting herbivore population growth, but how they interact to regulate herbivore populations is not well understood. We manipulated jasmonate-induced plant resistance, exposure to the natural predator community and herbivore density to test how these factors jointly and independently affect herbivore population growth. On low-resistance plants, the predator community was diverse and abundant, promoting high predator consumption rates. On high-resistance plants, the predator community was less diverse and abundant, resulting in low predator consumption rate. Plant resistance only directly regulated aphid population growth on predator-excluded plants. When predators were present, plant resistance indirectly regulated herbivore population growth by changing the impact of predators on the herbivorous prey. A possible mechanism for the interaction between plant resistance and predation is that methyl salicylate, a herbivore-induced plant volatile attractive to predators, was more strongly induced in low-resistance plants. Increased plant resistance reduced predator attractant lures, preventing predators from locating their prey. Low-resistance plants may regulate herbivore populations via predators by providing reliable information on prey availability and increasing the effectiveness of predators. © 2017 The Author(s).

  9. Climate change and the optimal flowering time of annual plants in seasonal environments.

    PubMed

    Johansson, Jacob; Bolmgren, Kjell; Jonzén, Niclas

    2013-01-01

    Long-term phenology monitoring has documented numerous examples of changing flowering dates during the last century. A pivotal question is whether these phenological responses are adaptive or not under directionally changing climatic conditions. We use a classic dynamic growth model for annual plants, based on optimal control theory, to find the fitness-maximizing flowering time, defined as the switching time from vegetative to reproductive growth. In a typical scenario of global warming, with advanced growing season and increased productivity, optimal flowering time advances less than the start of the growing season. Interestingly, increased temporal spread in production over the season may either advance or delay the optimal flowering time depending on overall productivity or season length. We identify situations where large phenological changes are necessary for flowering time to remain optimal. Such changes also indicate changed selection pressures. In other situations, the model predicts advanced phenology on a calendar scale, but no selection for early flowering in relation to the start of the season. We also show that the optimum is more sensitive to increased productivity when productivity is low than when productivity is high. All our results are derived using a general, graphical method to calculate the optimal flowering time applicable for a large range of shapes of the seasonal production curve. The model can thus explain apparent maladaptation in phenological responses in a multitude of scenarios of climate change. We conclude that taking energy allocation trade-offs and appropriate time scales into account is critical when interpreting phenological patterns.

  10. Intransitivity is infrequent and fails to promote annual plant coexistence without pairwise niche differences.

    PubMed

    Godoy, Oscar; Stouffer, Daniel B; Kraft, Nathan J B; Levine, Jonathan M

    2017-02-27

    Intransitive competition is often projected to be a widespread mechanism of species coexistence in ecological communities. However, it is unknown how much of the coexistence we observe in nature results from this mechanism when species interactions are also stabilized by pairwise niche differences. We combined field-parameterized models of competition among 18 annual plant species with tools from network theory to quantify the prevalence of intransitive competitive relationships. We then analyzed the predicted outcome of competitive interactions with and without pairwise niche differences. Intransitive competition was found for just 15 to 19% of the 816 possible triplets, and this mechanism was never sufficient to stabilize the coexistence of the triplet when the pair-wise niche differences between competitors were removed. Of the transitive and intransitive triplets, only four were predicted to coexist and these were more similar in multidimensional trait space defined by 11 functional traits than non-coexisting triplets. Our results argue that intransitive competition may be less frequent than recently posed, and that even when it does operate, pairwise niche differences may be key to possible coexistence. This article is protected by copyright. All rights reserved.

  11. Effect of temperature-transfer on growth of laboratory populations of a South American annual fish Cynolebias bellottii.

    PubMed

    Liu, R K; Leung, B E; Walford, R L

    1975-09-01

    Previous observation had shown that annual fish living at 15 degrees C grow faster and live longer than those at 20 degrees C. We now demonstrate that when populations of these fish undergo reciprocal transfer between these two temperatures, their growth rates change to that of animals living at the temperature into which they have been transferred. These growth rates do not entirely correlate with the longevity patterns observed in annual fish subjected to temperature-transfer, nor to certain other observations of the relationships among growth, temperature and longevity as reported in the literature.

  12. Egg clumping, host plant selection and population regulation in Cactoblastis cactorum (Lepidoptera).

    PubMed

    Myers, Judith H; Monro, John; Murray, Neil

    1981-10-01

    Since the successful control of prickly pear cactus by Cactoblastis cactorum in Australia, populations of plants and moths have persisted at low densities in open woodland sites. A contagious egg distribution causes overcrowding of larvae on some plants but insures low levels or no attack of other plants. This prevents extinction of plants and insects. Cactoblastis moths choose plants with characteristics which may increase the success of their larvae. Field observations and cage experiments indicate that large, green cactuses near previously attacked cactuses receive more eggs. Plants which are actively photosynthesizing are also more attractive as oviposition sites. These oviposition preferences contribute to the observed contagious egg distribution.While open woodland Opuntia and Cactoblastis populations fluctuate around an equilibrium, pasture populations may better be described by the "hide and seek" model, with the woodland populations serving as refuges. Average plant quality and variation in quality are suggested as important components in the dynamics of this system.

  13. Climate-associated population declines reverse recovery and threaten future of an iconic high-elevation plant

    USGS Publications Warehouse

    Krushelnycky, Paul D.; Loope, Lloyd L.; Giambelluca, Thomas W.; Starr, Forest; Starr, Kim; Drake, Donald R.; Taylor, Andrew D.; Robichaux, Robert H.

    2013-01-01

    Although climate change is predicted to place mountain-top and other narrowly endemic species at severe risk of extinction, the ecological processes involved in such extinctions are still poorly resolved. In addition, much of this biodiversity loss will likely go unobserved, and therefore largely unappreciated. The Haleakalā silversword is restricted to a single volcano summit in Hawai‘i, but is a highly charismatic giant rosette plant that is viewed by 1–2 million visitors annually. We link detailed local climate data to a lengthy demographic record, and combine both with a population-wide assessment of recent plant mortality and recruitment, to show that after decades of strong recovery following successful management, this iconic species has entered a period of substantial climate-associated decline. Mortality has been highest at the lower end of the distributional range, where most silverswords occur, and the strong association of annual population growth rates with patterns of precipitation suggests an increasing frequency of lethal water stress. Local climate data confirm trends toward warmer and drier conditions on the mountain, and signify a bleak outlook for silverswords if these trends continue. The silversword example foreshadows trouble for diversity in other biological hotspots, and illustrates how even well-protected and relatively abundant species may succumb to climate-induced stresses.

  14. Climate-associated population declines reverse recovery and threaten future of an iconic high-elevation plant.

    PubMed

    Krushelnycky, Paul D; Loope, Lloyd L; Giambelluca, Thomas W; Starr, Forest; Starr, Kim; Drake, Donald R; Taylor, Andrew D; Robichaux, Robert H

    2013-03-01

    Although climate change is predicted to place mountain-top and other narrowly endemic species at severe risk of extinction, the ecological processes involved in such extinctions are still poorly resolved. In addition, much of this biodiversity loss will likely go unobserved, and therefore largely unappreciated. The Haleakalā silversword is restricted to a single volcano summit in Hawai'i, but is a highly charismatic giant rosette plant that is viewed by 1-2 million visitors annually. We link detailed local climate data to a lengthy demographic record, and combine both with a population-wide assessment of recent plant mortality and recruitment, to show that after decades of strong recovery following successful management, this iconic species has entered a period of substantial climate-associated decline. Mortality has been highest at the lower end of the distributional range, where most silverswords occur, and the strong association of annual population growth rates with patterns of precipitation suggests an increasing frequency of lethal water stress. Local climate data confirm trends toward warmer and drier conditions on the mountain, and signify a bleak outlook for silverswords if these trends continue. The silversword example foreshadows trouble for diversity in other biological hotspots, and illustrates how even well-protected and relatively abundant species may succumb to climate-induced stresses.

  15. Inter-annual variability in spring abundance of adult Calanus finmarchicus from the overwintering population in the southeastern Norwegian Sea

    NASA Astrophysics Data System (ADS)

    Dupont, Nicolas; Bagøien, Espen; Melle, Webjørn

    2017-03-01

    Calanus finmarchicus is the dominant copepod species in the Norwegian Sea, where it plays a key role in the ecosystem by transferring energy from primary producers to higher trophic levels. This paper analyses a 17-year time series, 1996-2012, on C. finmarchicus collected within the Atlantic Water mass along the Svinøy transect in the southeastern Norwegian Sea. We use the spring abundance of adult as a proxy for the size of C. finmarchicus' overwintered population. The inter-annual trend in spring abundance of adult C. finmarchicus in the 200-0 m depth-stratum is assessed while accounting for spring population development to the adult stage represented by day of year for sampling, inter-annual changes in timing of population development, and spatial differences. For the most oceanic stations, a significant inter-annual trend in spring abundance of adult C. finmarchicus was revealed using generalized additive models (GAM). This trend primarily consists in an increase prior to year 2000 and a decrease between years 2000 and ca. 2011. For the stations closer to the coast, the identified inter-annual trend is a decrease during a longer period from the late 90s until ca. 2011. From 2000 to 2011, our estimates suggest a 50% decrease for the most oceanic stations, and as much as an 81% decrease for the stations closer to the coast. In addition the results suggest a consistent change in phenology over the years and the stations. The predicted spring peak of overwintered adult population abundance is suggested to become shorter by 3 days, and the predicted maximum of abundance to take place 4 days earlier over the 17 years of the time-series. The results highlight significant changes in intensity and timing of the overwintered population of a key zooplankton species in the Norwegian Sea that may have important implications on the scale of an entire ecosystem.

  16. Annual performance analysis and comparison of pellet production integrated with an existing combined heat and power plant.

    PubMed

    Song, Han; Dotzauer, Erik; Thorin, Eva; Yan, Jinyue

    2011-05-01

    Three optional pellet production processes integrated with an existing biomass-based CHP plant using different raw materials (wood chips and solid hydrolysis residues) are studied. The year is divided into 12 periods, and the integrated biorefinery systems are modeled and simulated for each period. The annual economic performance of three integrated biorefinery systems is analyzed based on the simulation results. The option of pellet production integrated with the existing CHP plant with the exhaust flue gas and superheated steam as drying mediums has the lowest specific pellet production cost of 105 €/t(pellet), the shortest payback time of less than 2 years and the greatest CO(2) reduction of the three options. An advantage in common among the three options is a dramatic increase of the total annual power production and significant CO(2) reduction in spite of a small decrease of power efficiency.

  17. Isolation and characterisation of 11 polymorphic microsatellite markers in Papaver rhoeas L. (Corn Poppy), a major annual plant species from cultivated areas.

    PubMed

    Kati, Vaya; Corre, Valérie Le; Michel, Séverine; Jaffrelo, Lydia; Poncet, Charles; Délye, Christophe

    2012-12-24

    Papaver rhoeas, an annual plant species in the Papaveraceae family, is part of the biodiversity of agricultural ecosystems and also a noxious agronomic weed. We developed microsatellite markers to study the genetic diversity of P. rhoeas, using an enriched microsatellite library coupled with 454 next-generation sequencing. A total of 13,825 sequences were obtained that yielded 1795 microsatellite loci. After discarding loci with less than six repeats of the microsatellite motif, automated primer design was successful for 598 loci. We tested 74 of these loci for amplification with a total of 97 primer pairs. Thirty loci passed our tests and were subsequently tested for polymorphism using 384 P. rhoeas plants originating from 12 populations from France. Of the 30 loci, 11 showed reliable polymorphism not affected by the presence of null alleles. The number of alleles and the expected heterozygosity ranged from 3 to 7.4 and from 0.27 to 0.73, respectively. A low but significant genetic differentiation among populations was observed (F(ST) = 0.04; p < 0.001). The 11 validated polymorphic microsatellite markers developed in this work will be useful in studies of genetic diversity and population structure of P. rhoeas, assisting in designing management strategies for the control or the conservation of this species.

  18. Isolation and Characterisation of 11 Polymorphic Microsatellite Markers in Papaver rhoeas L. (Corn Poppy), a Major Annual Plant Species from Cultivated Areas

    PubMed Central

    Kati, Vaya; Le Corre, Valérie; Michel, Séverine; Jaffrelo, Lydia; Poncet, Charles; Délye, Christophe

    2013-01-01

    Papaver rhoeas, an annual plant species in the Papaveraceae family, is part of the biodiversity of agricultural ecosystems and also a noxious agronomic weed. We developed microsatellite markers to study the genetic diversity of P. rhoeas, using an enriched microsatellite library coupled with 454 next-generation sequencing. A total of 13,825 sequences were obtained that yielded 1795 microsatellite loci. After discarding loci with less than six repeats of the microsatellite motif, automated primer design was successful for 598 loci. We tested 74 of these loci for amplification with a total of 97 primer pairs. Thirty loci passed our tests and were subsequently tested for polymorphism using 384 P. rhoeas plants originating from 12 populations from France. Of the 30 loci, 11 showed reliable polymorphism not affected by the presence of null alleles. The number of alleles and the expected heterozygosity ranged from 3 to 7.4 and from 0.27 to 0.73, respectively. A low but significant genetic differentiation among populations was observed (FST = 0.04; p < 0.001). The 11 validated polymorphic microsatellite markers developed in this work will be useful in studies of genetic diversity and population structure of P. rhoeas, assisting in designing management strategies for the control or the conservation of this species. PMID:23263674

  19. [Genetic effects in populations of plants growing in the zone of Kyshtym and Chernobyl accidents].

    PubMed

    Shevchenko, V A; Kal'chenko, V A; Abramov, V I; Rubanovich, A V; Shevchenko, V V; Grinikh, L I

    1999-01-01

    Studies to analyze the genetic processes in natural populations of plants were started on the territory of the East-Ural Radioactive Trace (EURT) in 1962 and in the zone of the Chernobyl accident in May 1986. The main directions of the genetic studies in both radioactive areas were similar: 1) study of the mutation process intensity depending on the dose and dose rate and analysis of dose-effect relationships for different genetic changes (point mutations, chromosome aberrations in mitosis and meiosis) in irradiated plant populations; 2) study of the mutation process dynamics in generations of chronically (prolongly) irradiated populations of plants; 3) analysis of microevolutionary processes in irradiated plant populations. The report presents an analysis of observed dose-effect relationships under the action of radiation on populations of Arabidopsis thaliana, Pinus sylvestris and a number of other plant species. Analysis of the mutation processes dynamics in 8 Arabidopsis populations growing in the zone of the Chernobyl catastrophe has demonstrated that the level of the embryo lethal mutations 10 years after the accident in the irradiated populations significantly exceeds the control level. The following phenomena observed in chronically irradiated populations have also been considered: increased radioresistance of irradiated populations (radioadaptation), the appearance of abnormal karyotypes and selective markers upon chronic irradiation. The authors call attention to the high importance of monitoring of genetic processes in irradiated plant populations for understanding of the action of radiation on human populations.

  20. Occurrence of the non-native annual bluegrass on the Antarctic mainland and its negative effects on native plants.

    PubMed

    Molina-Montenegro, Marco A; Carrasco-Urra, Fernando; Rodrigo, Cristian; Convey, Peter; Valladares, Fernando; Gianoli, Ernesto

    2012-08-01

    Few non-native species have colonized Antarctica, although increased human activity and accelerated climate change may increase their number, distributional range, and effects on native species on the continent. We searched 13 sites on the maritime Antarctic islands and 12 sites on the Antarctic Peninsula for annual bluegrass (Poa annua), a non-native flowering plant. We also evaluated the possible effects of competition between P. annua and 2 vascular plants native to Antarctica, Antarctic pearlwort (Colobanthus quitensis) and Antarctic hairgrass (Deschampsia antarctica). We grew the native species in experimental plots with and without annual bluegrass under conditions that mimicked the Antarctic environment. After 5 months, we measured photosynthetic performance on the basis of chlorophyll fluorescence and determined total biomass of both native species. We found individual specimens of annual bluegrass at 3 different sites on the Antarctic Peninsula during the 2007-2008 and 2009-2010 austral summers. The presence of bluegrass was associated with a statistically significant reduction in biomass of pearlwort and hairgrass, whereas the decrease in biomass of bluegrass was not statistically significant. Similarly, the presence of bluegrass significantly reduced the photosynthetic performance of the 2 native species. Sites where bluegrass occurred were close to major maritime routes of scientific expeditions and of tourist cruises to Antarctica. We believe that if current levels of human activity and regional warming persist, more non-native plant species are likely to colonize the Antarctic and may affect native species.

  1. Population rules can apply to individual plants and affect their architecture: an evaluation on the cushion plant Mulinum spinosum (Apiaceae)

    PubMed Central

    Puntieri, Javier G.; Damascos, María A.; Llancaqueo, Yanina; Svriz, Maya

    2010-01-01

    Background and aims Plants are regarded as populations of modules such as axes and growth units (GUs, i.e. seasonally produced axis segments). Due to their dense arrays of GUs, cushion plants may resemble crowded plant populations in the way the number of components (GUs in plants, individuals in populations) relates to their individual sizes. Methodology The morphological differentiation of GUs and its relationship with biomass accumulation and plant size were studied for the cushion subshrub Mulinum spinosum (Apiaceae), a widespread species in dry areas of Patagonia. In 2009, GUs were sampled from one-quarter of each of 24 adult plants. Within- and between-plant variations in GU length, diameter, number of nodes and biomass were analysed and related to whole-plant size. Principal results Each year, an M. spinosum cushion develops flowering GUs and vegetative GUs. Flowering GUs are larger, twice as numerous and contain two to four times more dry mass (excluding reproductive structures) than vegetative GUs. The hemispherical area of the cushions was positively correlated with the biomass of last-year GUs. The biomass of flowering GUs was negatively correlated with the density of GUs. Mulinum spinosum plants exhibited a notable differentiation between flowering and vegetative GUs, but their axes, i.e. the sequences of GUs, were not differentiated throughout the plants. Flowering GUs comprised a major proportion of each plant's photosynthetic tissues. Conclusions A decrease in the size of flowering GUs and in their number relative to the total number of GUs per plant, parallel to an increase in GU density, is predicted as M. spinosum plants age over years. The assimilative role of vegetative GUs is expected to increase in summer because of their less exposed position in the cushion. These GUs would therefore gain more from warm and dry conditions than flowering GUs. PMID:22476077

  2. Population rules can apply to individual plants and affect their architecture: an evaluation on the cushion plant Mulinum spinosum (Apiaceae).

    PubMed

    Puntieri, Javier G; Damascos, María A; Llancaqueo, Yanina; Svriz, Maya

    2010-01-01

    Plants are regarded as populations of modules such as axes and growth units (GUs, i.e. seasonally produced axis segments). Due to their dense arrays of GUs, cushion plants may resemble crowded plant populations in the way the number of components (GUs in plants, individuals in populations) relates to their individual sizes. The morphological differentiation of GUs and its relationship with biomass accumulation and plant size were studied for the cushion subshrub Mulinum spinosum (Apiaceae), a widespread species in dry areas of Patagonia. In 2009, GUs were sampled from one-quarter of each of 24 adult plants. Within- and between-plant variations in GU length, diameter, number of nodes and biomass were analysed and related to whole-plant size. Each year, an M. spinosum cushion develops flowering GUs and vegetative GUs. Flowering GUs are larger, twice as numerous and contain two to four times more dry mass (excluding reproductive structures) than vegetative GUs. The hemispherical area of the cushions was positively correlated with the biomass of last-year GUs. The biomass of flowering GUs was negatively correlated with the density of GUs. Mulinum spinosum plants exhibited a notable differentiation between flowering and vegetative GUs, but their axes, i.e. the sequences of GUs, were not differentiated throughout the plants. Flowering GUs comprised a major proportion of each plant's photosynthetic tissues. A decrease in the size of flowering GUs and in their number relative to the total number of GUs per plant, parallel to an increase in GU density, is predicted as M. spinosum plants age over years. The assimilative role of vegetative GUs is expected to increase in summer because of their less exposed position in the cushion. These GUs would therefore gain more from warm and dry conditions than flowering GUs.

  3. Quantitative Relationship of Soil Texture with the Observed Population Density Reduction of Heterodera glycines after Annual Corn Rotation in Nebraska

    PubMed Central

    Pérez-Hernández, Oscar; Giesler, Loren J.

    2014-01-01

    Soil texture has been commonly associated with the population density of Heterodera glycines (soybean cyst nematode: SCN), but such an association has been mainly described in terms of textural classes. In this study, multivariate analysis and a generalized linear modeling approach were used to elucidate the quantitative relationship of soil texture with the observed SCN population density reduction after annual corn rotation in Nebraska. Forty-five commercial production fields were sampled in 2009, 2010, and 2011 and SCN population density (eggs/100 cm3 of soil) for each field was determined before (Pi) and after (Pf) annual corn rotation from ten 3 × 3-m sampling grids. Principal components analysis revealed that, compared with silt and clay, sand had a stronger association with SCN Pi and Pf. Cluster analysis using the average linkage method and confirmed through 1,000 bootstrap simulations identified two groups: one corresponding to predominant silt-and-clay fields and other to sand-predominant fields. This grouping suggested that SCN relative percent population decline was higher in the sandy than in the silt-and-clay predominant group. However, when groups were compared for their SCN population density reduction using Pf as the response, Pi as a covariate, and incorporating the year and field variability, a negative binomial generalized linear model indicated that the SCN population density reduction was not statistically different between the sand-predominant field group and the silt-and-clay predominant group. PMID:24987160

  4. Population dynamics of a monocarpic thistle: simulated effects of reproductive timing and grazing of flowering plants

    NASA Astrophysics Data System (ADS)

    Ramula, Satu

    2008-03-01

    In monocarpic plants, which die after flowering once, the timing of reproduction plays an important role. The optimal time for reproduction is when reproductive output and survival are maximized. This optimum may be altered by herbivores that consume reproductive plants of different sizes disproportionally. I examined plant survival, flowering probability, reproductive output and the probability of becoming grazed in relation to plant size in two populations of the short-lived monocarpic herb Cirsium palustre. Moreover, I simulated the consequences of changes in reproductive timing and grazing preference for population dynamics. Plant survival, flowering probability and reproductive output tended to increase with plant size, whereas the probability of becoming grazed was unaffected by plant size. According to the stochastic simulations, intense grazing would have been required to significantly reduce the stochastic population growth rate (log λs) and therefore, the observed levels of grazing had no impact on log λs in the study populations. Stochastic simulations conducted with selective grazing focusing on either early or late flowering plants and with different reproductive timings revealed that the grazing of early flowering plants had a constant effect on log λs despite the proportions of early and late flowering plants in the population, suggesting that there is no optimal time for reproduction. The grazing of late flowering plants reduced log λs with delayed reproduction, favouring reproduction early in the life cycle.

  5. Annual water quality data report for the Waste Isolation Pilot Plant

    SciTech Connect

    Lyon, M.L. )

    1989-04-01

    This is the fourth Annual Water Quality Data Report for the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. The WIPP project is operated by the United States Department of Energy (DOE) for the purpose of providing a research and development facility to demonstrate the safe disposal of transuranic radioactive wastes generated by the defense activities of the United States Government. This report presents water quality data collected from January 1988 through December 1988 from 16 designated pre-operational (WIPP facility) monitoring wells, two additional wells, and 10 privately-owned wells in the vicinity of the WIPP. Additionally, water samples were collected from the Air Intake Shaft during shaft construction activities at the WIPP. This report lists pertinent information regarding the monitoring wells sampled, sampling zone, dates pumped, and types of samples collected during 1988. Comparative data from previous samplings of all wells can be found in Uhland and Randall (1986), Uhland et al. (1987), Randall et al. (1988), as well as in this report. The data reported by the Water Quality Sampling Program in this and previous reports indicate that serial sampling is a very useful tool in determining sample representativeness from wells in the WIPP vicinity. Serial sample field chemistry data are demonstrated to be highly accurate and precise as indicated by the excellent overall average percent spike recovery values and low RPD values reported for the sampling events. Serial sample field chemistry data and laboratory water quality parameter analyses gathered by the WQSP since January 1985 are the foundation for a pre-operational water quality baseline at the WIPP. 32 refs., 66 figs., 96 tabs.

  6. 1997 annual ground control operating plan for the Waste Isolation Pilot Plant

    SciTech Connect

    1997-02-01

    This plan presents background information and a working guide to assist Mine Operations and Engineering in developing strategies for addressing ground control issues at the Waste Isolation Pilot Plant (WIPP). With the anticipated receipt of waste in late 1997, this document provides additional detail to Panel 1 activities and options. The plan also serves as a foundation document for development and revision of the annual long-term ground control plan. Section 2.0 documents the current status of all underground excavations with respect to location, geology, geometry, age, ground support, operational use, projected life, and physical conditions. Section 3.0 presents the methods used to evaluate ground conditions, including visual observations of the roof, ribs, and floor, inspection of observation holes, and review of instrumentation data. Section 4.0 lists several ground support options and specific applications of each. Section 5.0 discusses remedial ground control measures that have been implemented to date. Section 6.0 presents projections and recommendations for ground control actions based on the information in Sections 2.0 through 5.0 of this plan and on a rating of the critical nature of each specific area. Section 7.0 presents a summary statement, and Section 8.0 includes references. Appendix A provides an overview and critique of ground control systems that have been, or may be, used at the site. Because of the dynamic nature of the underground openings and associated geotechnical activities, this plan will be revised as additional data are incorporated.

  7. Highly diverse endophytic and soil Fusarium oxysporum populations associated with field-grown tomato plants.

    PubMed

    Demers, Jill E; Gugino, Beth K; Jiménez-Gasco, María Del Mar

    2015-01-01

    The diversity and genetic differentiation of populations of Fusarium oxysporum associated with tomato fields, both endophytes obtained from tomato plants and isolates obtained from soil surrounding the sampled plants, were investigated. A total of 609 isolates of F. oxysporum were obtained, 295 isolates from a total of 32 asymptomatic tomato plants in two fields and 314 isolates from eight soil cores sampled from the area surrounding the plants. Included in this total were 112 isolates from the stems of all 32 plants, a niche that has not been previously included in F. oxysporum population genetics studies. Isolates were characterized using the DNA sequence of the translation elongation factor 1α gene. A diverse population of 26 sequence types was found, although two sequence types represented nearly two-thirds of the isolates studied. The sequence types were placed in different phylogenetic clades within F. oxysporum, and endophytic isolates were not monophyletic. Multiple sequence types were found in all plants, with an average of 4.2 per plant. The population compositions differed between the two fields but not between soil samples within each field. A certain degree of differentiation was observed between populations associated with different tomato cultivars, suggesting that the host genotype may affect the composition of plant-associated F. oxysporum populations. No clear patterns of genetic differentiation were observed between endophyte populations and soil populations, suggesting a lack of specialization of endophytic isolates. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Highly Diverse Endophytic and Soil Fusarium oxysporum Populations Associated with Field-Grown Tomato Plants

    PubMed Central

    Demers, Jill E.; Gugino, Beth K.

    2014-01-01

    The diversity and genetic differentiation of populations of Fusarium oxysporum associated with tomato fields, both endophytes obtained from tomato plants and isolates obtained from soil surrounding the sampled plants, were investigated. A total of 609 isolates of F. oxysporum were obtained, 295 isolates from a total of 32 asymptomatic tomato plants in two fields and 314 isolates from eight soil cores sampled from the area surrounding the plants. Included in this total were 112 isolates from the stems of all 32 plants, a niche that has not been previously included in F. oxysporum population genetics studies. Isolates were characterized using the DNA sequence of the translation elongation factor 1α gene. A diverse population of 26 sequence types was found, although two sequence types represented nearly two-thirds of the isolates studied. The sequence types were placed in different phylogenetic clades within F. oxysporum, and endophytic isolates were not monophyletic. Multiple sequence types were found in all plants, with an average of 4.2 per plant. The population compositions differed between the two fields but not between soil samples within each field. A certain degree of differentiation was observed between populations associated with different tomato cultivars, suggesting that the host genotype may affect the composition of plant-associated F. oxysporum populations. No clear patterns of genetic differentiation were observed between endophyte populations and soil populations, suggesting a lack of specialization of endophytic isolates. PMID:25304514

  9. The balance of planting and mortality in a street tree population

    Treesearch

    Lara A. Roman; John J. Battles; Joe R. McBride

    2013-01-01

    Street trees have aesthetic, environmental, human health, and economic benefits in urban ecosystems. Street tree populations are constructed by cycles of planting, growth, death, removal and replacement. The goals of this study were to understand how tree mortality and planting rates affect net population growth, evaluate the shape of the mortality curve, and assess...

  10. Wild Plant Species with Extremely Small Populations Require Conservation and Reintroduction in China

    Treesearch

    Hai Ren; Qianmei Zhang; Hongfang Lu; Hongxiao Liu; Qinfeng Guo; Jun Wang; Shuguang Jian; Hai’ou Bao

    2012-01-01

    China is exceptionally rich in biodiversity, with more than 30000 vascular plant species that include many endemic genera, species of ancient origin, and cultivated plants (Yang et al. 2005). Because of rapid economic development, population growth, pollution, and continuing resource exploitation, China’s plant diversity faces severe threats. According to the Chinese...

  11. Tillage Requirments for integrating winter-annual grazing in peanut production: Plant water status and productivity

    USDA-ARS?s Scientific Manuscript database

    The use of crop rotation systems involving winter-annual grazing can help peanut (Arachis hypogaea L.) producers increase profitability, although winter-annual grazing could result in excessive soil compaction, which can severely limit yields. We conducted a 3-yr field study on a Dothan loamy sand i...

  12. Systems Modeling at Multiple Levels of Regulation: Linking Systems and Genetic Networks to Spatially Explicit Plant Populations

    PubMed Central

    Kitchen, James L.; Allaby, Robin G.

    2013-01-01

    Selection and adaptation of individuals to their underlying environments are highly dynamical processes, encompassing interactions between the individual and its seasonally changing environment, synergistic or antagonistic interactions between individuals and interactions amongst the regulatory genes within the individual. Plants are useful organisms to study within systems modeling because their sedentary nature simplifies interactions between individuals and the environment, and many important plant processes such as germination or flowering are dependent on annual cycles which can be disrupted by climate behavior. Sedentism makes plants relevant candidates for spatially explicit modeling that is tied in with dynamical environments. We propose that in order to fully understand the complexities behind plant adaptation, a system that couples aspects from systems biology with population and landscape genetics is required. A suitable system could be represented by spatially explicit individual-based models where the virtual individuals are located within time-variable heterogeneous environments and contain mutable regulatory gene networks. These networks could directly interact with the environment, and should provide a useful approach to studying plant adaptation. PMID:27137364

  13. Genetic structure of colline and montane populations of an endangered plant species

    PubMed Central

    Maurice, Tiphaine; Matthies, Diethart; Muller, Serge; Colling, Guy

    2016-01-01

    Due to land-use intensification, lowland and colline populations of many plants of nutrient-poor grasslands have been strongly fragmented in the last decades, with potentially negative consequences for their genetic diversity and persistence. Populations in mountains might represent a genetic reservoir for grassland plants, because they have been less affected by land-use changes. We studied the genetic structure and diversity of colline and montane Vosges populations of the threatened perennial plant Arnica montana in western central Europe using AFLP markers. Our results indicate that in contrast to our expectation even strongly fragmented colline populations of A. montana have conserved a considerable amount of genetic diversity. However, mean seed mass increased with the proportion of polymorphic loci, suggesting inbreeding effects in low diversity populations. At a similar small geographical scale, there was a clear IBD pattern for the montane Vosges but not for the colline populations. However, there was a strong IBD-pattern for the colline populations at a large geographical scale suggesting that this pattern is a legacy of historical gene flow, as most of the colline populations are today strongly isolated from each other. Genetic differentiation between colline and montane Vosges populations was strong. Moreover, results of a genome scan study indicated differences in loci under selection, suggesting that plants from montane Vosges populations might be maladapted to conditions at colline sites. Our results suggest caution in using material from montane populations of rare plants for the reinforcement of small genetically depauperate lowland populations. PMID:27519913

  14. Genetic structure of colline and montane populations of an endangered plant species.

    PubMed

    Maurice, Tiphaine; Matthies, Diethart; Muller, Serge; Colling, Guy

    2016-08-12

    Due to land-use intensification, lowland and colline populations of many plants of nutrient-poor grasslands have been strongly fragmented in the last decades, with potentially negative consequences for their genetic diversity and persistence. Populations in mountains might represent a genetic reservoir for grassland plants, because they have been less affected by land-use changes. We studied the genetic structure and diversity of colline and montane Vosges populations of the threatened perennial plant Arnica montana in western central Europe using AFLP markers. Our results indicate that in contrast to our expectation even strongly fragmented colline populations of A. montana have conserved a considerable amount of genetic diversity. However, mean seed mass increased with the proportion of polymorphic loci, suggesting inbreeding effects in low diversity populations. At a similar small geographical scale there was a clear IBD pattern for the montane Vosges but not for the colline populations. However, there was a strong IBD-pattern for the colline populations at a large geographical scale suggesting that this pattern is a legacy of historical gene flow, as most of the colline populations are today strongly isolated from each other. Genetic differentiation between colline and montane Vosges populations was strong. Moreover, results of a genome scan study indicated differences in loci under selection, suggesting that plants from montane Vosges populations might be maladapted to conditions at colline sites. Our results suggest caution in using material from montane populations of rare plants for the reinforcement of small genetically depauperate lowland populations.

  15. Germination traits explain soil seed persistence across species: the case of Mediterranean annual plants in cereal fields

    PubMed Central

    Saatkamp, Arne; Affre, Laurence; Dutoit, Thierry; Poschlod, Peter

    2011-01-01

    Background and Aims Seed persistence in the soil under field conditions is an important issue for the maintenance of local plant populations and the restoration of plant communities, increasingly so in the light of rapidly changing land use and climate change. Whereas processes important for dispersal in space are well known, knowledge of processes governing dispersal in time is still limited. Data for morphological seed traits such as size have given contradictory results for prediction of soil seed persistence or cover only a few species. There have been few experimental studies on the role of germination traits in determining soil seed persistence, while none has studied their predictive value consistently across species. Delayed germination, as well as light requirements for germination, have been suggested to contribute to the formation of persistent seed banks. Moreover, diurnally fluctuating temperatures can influence the timing of germination and are therefore linked to seed bank persistence. Methods The role of germination speed measured by T50 (days to germination of 50 % of all germinated seeds), light requirement and reaction to diurnally fluctuating temperatures in determining seed persistence in the soil was evaluated using an experimental comparative data set of 25 annual cereal weed species. Key Results It is shown that light requirements and slow germination are important features to maintain seeds ungerminated just after entering the soil, and hence influence survival of seeds in the soil. However, the detection of low diurnally fluctuating temperatures enhances soil seed bank persistence by limiting germination. Our data further suggest that the effect of diurnally fluctuating temperatures, as measured on seeds after dispersal and dry storage, is increasingly important to prevent fatal germination after longer burial periods. Conclusions These results underline the functional role of delayed germination and light for survival of seeds in the soil

  16. Over-expression of an FT-homologous gene of apple induces early flowering in annual and perennial plants.

    PubMed

    Tränkner, Conny; Lehmann, Sandra; Hoenicka, Hans; Hanke, Magda-Viola; Fladung, Matthias; Lenhardt, Denise; Dunemann, Frank; Gau, Achim; Schlangen, Karin; Malnoy, Mickael; Flachowsky, Henryk

    2010-11-01

    The protein encoded by the FLOWERING LOCUS T (FT) gene from Arabidopsis thaliana seems to be the long-searched florigen, and over-expression of FT orthologues resulted in accelerated flower development in annual and perennial plants. In the present study, we isolated two allelic mRNA sequences of an FT-homologous gene from apple, which was designated as MdFT1. Using a SSR motif this gene was mapped on LG 12 of apple. Over-expression of MdFT1 in Arabidopsis and the commercially important tree species poplar and apple itself using the CaMV 35S or the Arabidopsis Suc2 promoter resulted in significant accelerated flowering compared with wild-type plants. Transgenic T(0) plants of Arabidopsis flowered 4-6 days on average earlier than wild-type Arabidopsis under LD conditions. Under short-day conditions Suc2::MdFT1 plants of the T(1)-generation flowered after 66 ± 18 days, while wild-type plants flowered about 22 days later. All transgenic Arabidopsis plants showed a normal habit except for the early flowering phenotype. Early flowering was detected 6-10 months after transformation in transgenic polar clones containing MdFT1 driven by the CaMV 35S, whereas plants of the transgenic apple clone T780 set up its first flowers during in vitro cultivation. Based on our results we conclude that MdFT1 is responsible for inducing flowering and that the function of the apple FT1 gene is conserved in annual herbaceous species as well as perennial woody species. Furthermore, we discuss the role of MdFT1 in flower development with regard to the findings of genetic studies on apple.

  17. Comprehensive cooling water study annual report. Volume VIII: semi-aquatic vertebrates, Savannah River Plant

    SciTech Connect

    Gladden, J.B.; Lower, M.W.; Mackey, H.E.; Specht, W.L.; Wilde, E.W.

    1985-07-01

    Several semi-aquatic vertebrate species are regularly observed in ''natural'' and ''post-thermal'' environments at SRP. Fewer species are regularly observed in thermally-altered areas. Yellow-bellied slider turtles, however, seem to thrive in areas of mildly elevated temperatures where they exhibit larger female body size than specimens from some ambient temperature areas of the SRP. Yellow-bellied slider turtles are the predominant species of semi-aquatic turtle on the SRP. Research conducted during 1984 was aimed toward examination of the activity levels of these animals, and their movement patterns within and among thermally- and nonthermally-altered wetlands on the SRP. Additional studies conducted on movement patterns of turtles in relation to reproduction examined emigration rates in five species of turtles during years of normal rainfall compared with a year of drought at a Carolina Bay. Studies of body size of slider turtles showed that animals inhabiting thermally-altered areas attain larger sizes than do individuals from ambient areas, presumably because the elevated temperatures allow for longer annual activity and feeding periods. Slider turtles from coastal, and from thermally- and nonthermally-altered inland populations, were examined for relationships between growth and clutch parameters. Slider turtles from an area of radioactive contamination were also studied for a determination of strontium-90 and cesium-137 bio-elimination. Studies of the brown water snake in the vicinity of Steel Creek and in the vicinity of Upper Three Runs Creek showed that these animals are primarily diurnal and prefer cool water temperatures. Preliminary sampling was initiated in 1984 to determine the structure of the Steel Creek snake community. 65 refs., 5 figs., 26 tabs.

  18. Succession of Phylogeny and Function During Plant Litter Decomposition (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Brodie, Eoin

    2013-03-01

    Eoin Brodie of Berkeley Lab on "Succession of phylogeny and function during plant litter decomposition" at the 8th Annual Genomics of Energy & Environment Meeting on March 27, 2013 in Walnut Creek, Calif.

  19. The Challenges and Opportunities for Extending Plant Genomics to Climate (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Weston, David

    2013-03-01

    David Weston of Oak Ridge National Laboratory on "The challenges and opportunities for extending plant genomics to climate" at the 8th Annual Genomics of Energy & Environment Meeting on March 27, 2013 in Walnut Creek, Calif.

  20. Delineating Molecular Interaction Mechanisms in an In Vitro Microbial-Plant Community (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Larsen, Peter

    2013-03-01

    Peter Larsen of Argonne National Lab on "Delineating molecular interaction mechanisms in an in vitro microbial-plant community" at the 8th Annual Genomics of Energy & Environment Meeting in Walnut Creek, Calif.

  1. Modulation of Root Microbiome Community Assembly by the Plant Immune Response (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Lebeis, Sarah

    2013-03-01

    Sarah Lebeis of University of North Carolina on "Modulation of root microbiome community assembly by the plant immune response" at the 8th Annual Genomics of Energy & Environment Meeting on March 28, 2013 in Walnut Creek, Calif.

  2. New Approaches and Technologies to Sequence de novo Plant reference Genomes (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Schmutz, Jeremy

    2013-03-01

    Jeremy Schmutz of the HudsonAlpha Institute for Biotechnology on "New approaches and technologies to sequence de novo plant reference genomes" at the 8th Annual Genomics of Energy & Environment Meeting on March 27, 2013 in Walnut Creek, Calif.

  3. The Genome of Selaginella: A Remnant of an Ancient Vascular Plant Lineage (JGI Seventh Annual User Meeting, 2012: Genomics of Energy and Environment)

    ScienceCinema

    Banks, Jody [Purdue University

    2016-07-12

    Jody Banks from Purdue University on "The Genome of Selaginella, a Remnant of an Ancient Vascular Plant Lineage" at the 7th Annual Genomics of Energy & Environment Meeting on March 21, 2012 in Walnut Creek, Calif.

  4. The Genome of Selaginella: A Remnant of an Ancient Vascular Plant Lineage (JGI Seventh Annual User Meeting, 2012: Genomics of Energy and Environment)

    SciTech Connect

    Banks, Jody

    2012-03-21

    Jody Banks from Purdue University on "The Genome of Selaginella, a Remnant of an Ancient Vascular Plant Lineage" at the 7th Annual Genomics of Energy & Environment Meeting on March 21, 2012 in Walnut Creek, Calif.

  5. Reduced fecundity in small populations of the rare plant Gentianopsis ciliate (Gentianaceae)

    USGS Publications Warehouse

    Robbins, C.S.

    1983-01-01

    Habitat destruction is the main cause for the biodiversity crisis. Surviving populations are often fragmented, i.e., small and isolated from each other. Reproduction of plants in small populations is often reduced, and this has been attributed to inbreeding depression, reduced attractiveness for pollinators, and reduced habitat quality in small populations. Here we present data on the effects of fragmentation on the rare, self-compatible perennial herb Gentianopsis ciliata (Gentianaceae), a species with very small and presumably well-dispersed seeds. We studied the relationship between population size, plant size, and the number of flowers produced in 63 populations from 1996-1998. In one of the years, leaf and flower size and the number of seeds produced per fruit was studied in a subset of 25 populations. Plant size, flower size, and the number of seeds per fruit and per plant increased with population size, whereas leaf length and the number of flowers per plant did not. The effects of population size on reproduction and on flower size remained significant if the effects were adjusted for differences in plant size, indicating that they could not be explained by differences in habitat quality. The strongly reduced reproduction in small populations may be due to pollination limitation, while the reduced flower size could indicate genetic effects.

  6. Reduced fecundity in small populations of the rare plant Gentianopsis ciliate (Gentianaceae)

    USGS Publications Warehouse

    Kery, M.; Matthies, D.

    2004-01-01

    Habitat destruction is the main cause for the biodiversity crisis. Surviving populations are often fragmented, i.e., small and isolated from each other. Reproduction of plants in small populations is often reduced, and this has been attributed to inbreeding depression, reduced attractiveness for pollinators, and reduced habitat quality in small populations. Here we present data on the effects of fragmentation on the rare, self-compatible perennial herb Gentianopsis ciliata (Gentianaceae), a species with very small and presumably well-dispersed seeds. We studied the relationship between population size, plant size, and the number of flowers produced in 63 populations from 1996-1998. In one of the years, leaf and flower size and the number of seeds produced per fruit was studied in a subset of 25 populations. Plant size, flower size, and the number of seeds per fruit and per plant increased with population size, whereas leaf length and the number of flowers per plant did not. The effects of population size on reproduction and on flower size remained significant if the effects were adjusted for differences in plant size, indicating that they could not be explained by differences in habitat quality. The strongly reduced reproduction in small populations may be due to pollination limitation, while the reduced flower size could indicate genetic effects.

  7. Host Plant Determines the Population Size of an Obligate Symbiont (Buchnera aphidicola) in Aphids.

    PubMed

    Zhang, Yuan-Chen; Cao, Wen-Jie; Zhong, Le-Rong; Godfray, H Charles J; Liu, Xiang-Dong

    2016-04-01

    Buchnera aphidicolais an obligate endosymbiont that provides aphids with several essential nutrients. Though much is known about aphid-Buchnera interactions, the effect of the host plant on Buchnera population size remains unclear. Here we used quantitative PCR (qPCR) techniques to explore the effects of the host plant on Buchnera densities in the cotton-melon aphid, Aphis gossypii Buchneratiters were significantly higher in populations that had been reared on cucumber for over 10 years than in populations maintained on cotton for a similar length of time. Aphids collected in the wild from hibiscus and zucchini harbored more Buchnera symbionts than those collected from cucumber and cotton. The effect of aphid genotype on the population size of Buchnera depended on the host plant upon which they fed. When aphids from populations maintained on cucumber or cotton were transferred to novel host plants, host survival and Buchnera population size fluctuated markedly for the first two generations before becoming relatively stable in the third and later generations. Host plant extracts from cucumber, pumpkin, zucchini, and cowpea added to artificial diets led to a significant increase in Buchnera titers in the aphids from the population reared on cotton, while plant extracts from cotton and zucchini led to a decrease in Buchnera titers in the aphids reared on cucumber. Gossypol, a secondary metabolite from cotton, suppressed Buchnera populations in populations from both cotton and cucumber, while cucurbitacin from cucurbit plants led to higher densities. Together, the results suggest that host plants influence Buchnera population processes and that this may provide phenotypic plasticity in host plant use for clonal aphids.

  8. Host Plant Determines the Population Size of an Obligate Symbiont (Buchnera aphidicola) in Aphids

    PubMed Central

    Zhang, Yuan-Chen; Cao, Wen-Jie; Zhong, Le-Rong; Godfray, H. Charles J.

    2016-01-01

    Buchnera aphidicola is an obligate endosymbiont that provides aphids with several essential nutrients. Though much is known about aphid-Buchnera interactions, the effect of the host plant on Buchnera population size remains unclear. Here we used quantitative PCR (qPCR) techniques to explore the effects of the host plant on Buchnera densities in the cotton-melon aphid, Aphis gossypii. Buchnera titers were significantly higher in populations that had been reared on cucumber for over 10 years than in populations maintained on cotton for a similar length of time. Aphids collected in the wild from hibiscus and zucchini harbored more Buchnera symbionts than those collected from cucumber and cotton. The effect of aphid genotype on the population size of Buchnera depended on the host plant upon which they fed. When aphids from populations maintained on cucumber or cotton were transferred to novel host plants, host survival and Buchnera population size fluctuated markedly for the first two generations before becoming relatively stable in the third and later generations. Host plant extracts from cucumber, pumpkin, zucchini, and cowpea added to artificial diets led to a significant increase in Buchnera titers in the aphids from the population reared on cotton, while plant extracts from cotton and zucchini led to a decrease in Buchnera titers in the aphids reared on cucumber. Gossypol, a secondary metabolite from cotton, suppressed Buchnera populations in populations from both cotton and cucumber, while cucurbitacin from cucurbit plants led to higher densities. Together, the results suggest that host plants influence Buchnera population processes and that this may provide phenotypic plasticity in host plant use for clonal aphids. PMID:26850304

  9. Divergent host-plant use promotes reproductive isolation among cynipid gall wasp populations.

    PubMed

    Egan, Scott P; Hood, Glen R; Feder, Jeff L; Ott, James R

    2012-08-23

    Ecological speciation occurs when reproductive isolation evolves as a consequence of divergent natural selection among environments. A direct prediction of this process is that ecologically divergent pairs of populations will exhibit greater reproductive isolation than ecologically similar pairs of populations. By comparing allopatric populations of the cynipid gall wasp Belonocnema treatae infesting Quercus virginiana and Quercus geminata, we tested the role that divergent host use plays in generating ecological divergence and sexual isolation. We found differences in body size and gall structure associated with divergent host use, but no difference in neutral genetic divergence between populations on the same or different host plant. We observed significant assortative mating between populations from alternative host plants but not between allopatric populations on the same host plant. Thus, we provide evidence that divergent host use promotes speciation among gall wasp populations.

  10. Comprehensive cooling water study annual report. Volume X: endangered species, Savannah River Plant

    SciTech Connect

    Gladden, J.B.; Lower, M.W.; Mackey, H.E.; Specht, W.L.; Wilde, E.W.

    1985-07-01

    Federally endangered species which occur on the Savannah River Plant (SRP) include the American alligator, red-cockaded woodpecker, the shortnose sturgeon, and the wood stork. Of these species, only the alligator, sturgeon, and wood stork are likely to be affected by the intake or release of cooling water at the SRP. The nearest colony of wood storks to the SRP is the Birdsville Colony, about 40-45 km southwest of potential foraging areas in the SRP Savannah River swamp. In 1983, it contained about six percent of the nesting pairs in the United States and produced about 250 fledglings. Its reproductive success was about the same in 1984. Based on the results of surveys made of foraging areas, both on SRP and offsite in 1983 and 1984, forage fish availability could be reduced by increased water depths in the Steel Creek delta area following L-Reactor restart with once-through cooling. Effluent discharge from SRP facilities probably limits the potential use of the SRP Savannah River swamp by foraging wood storks. The SRP supports a low-to-moderate alligator population. The current information available on the alligators of the SRP suggests that populations in suitable habitats (e.g., Beaver Dam Creek, Steel Creek, and Par Pond) should continue to benefit from the protection provided by the SRP and should remain stable or continue to increase. Based upon information from the literature and fisheries data for the Savannah River, the operations of the SRP do not appear to have adverse effects on the shortnose sturgeon. Based on known life history characteristics, there is no indication that spawning, rearing, or foraging habitats are affected by SRP operations. 64 refs., 20 figs., 12 tabs.

  11. Managing soil nitrogen to restore annual grass infested plant communities: an effective strategy or incomplete framework?

    USDA-ARS?s Scientific Manuscript database

    Theoretical and empirical work has established a positive relationship between resource availability and habitat invasibility. For invasive annual grasses, similar to other invasive species, invader success has been most often tied to increases in nitrogen (N) availability. These observations have...

  12. Long-term persistence of a neotropical ant-plant population in the absence of obligate plant-ants.

    PubMed

    Moraes, Sinara C; Vasconcelos, Heraldo L

    2009-09-01

    Interactions between ants and ant-plants are considered classic examples of obligate mutualisms. Previous studies have indicated that for many ant-plants the loss of ant colonies results in severe defoliation or mortality. Although individual plants can persist for some period of time without their mutualistic partners, to date populations of ant-free plants have only been recorded at high altitudes or on remote islands where herbivores are also scarce. We studied the interaction between ants, herbivores, and the ant-plant Tococa guianensis in the Cerrado region of central Brazil. Using a survey conducted across a large geographic region, we show that there is interpopulation variation in ant occupancy across sites and habitats. At most sites surveyed, plants were inhabited by Allomerus octoarticulatus, an obligate plant-ant. Plants with obligate ants had significantly lower standing levels of herbivore damage than plants with opportunistic ants and plants with no ant occupants. Furthermore, experimental removal of A. octoarticulatus resulted in increased levels of damage in both young and mature leaves. Despite the protection provided by obligate ants, populations of T. guianensis were found to persist without these ants in some areas. Plants without A. octoarticulatus had significantly greater leaf toughness and trichome density than those with A. octoarticulatus. Furthermore, trichome density in plants with A. octoarticulatus increased after ants were removed, probably as a response induced by increased levels of herbivore damage. To our knowledge, this is the first record of the occurrence of native myrmecophyte populations without their mutualistic ants in mainland low-elevation sites. Several factors may help to explain the long-term persistence of T. guianensis populations without plant-ants in some areas of the Brazilian Cerrado, including its potential for induced morphological defenses against insect herbivores and selection for increased levels of

  13. Projecting changes in annual hydropower generation using regional runoff data: An assessment of the United States federal hydropower plants

    DOE PAGES

    Kao, Shih -Chieh; Sale, Michael J.; Ashfaq, Moetasim; ...

    2014-12-18

    Federal hydropower plants account for approximately half of installed US conventional hydropower capacity, and are an important part of the national renewable energy portfolio. Utilizing the strong linear relationship between the US Geological Survey WaterWatch runoff and annual hydropower generation, a runoff-based assessment approach is introduced in this study to project changes in annual and regional hydropower generation in multiple power marketing areas. Future climate scenarios are developed with a series of global and regional climate models, and the model output is bias-corrected to be consistent with observed data for the recent past. Using this approach, the median decrease inmore » annual generation at federal projects is projected to be less than –2 TWh, with an estimated ensemble uncertainty of ±9 TWh. Although these estimates are similar to the recently observed variability in annual hydropower generation, and may therefore appear to be manageable, significantly seasonal runoff changes are projected and it may pose significant challenges in water systems with higher limits on reservoir storage and operational flexibility. Lastly, future assessments will be improved by incorporating next-generation climate models, by closer examination of extreme events and longer-term change, and by addressing the interactions among hydropower and other water uses.« less

  14. Projecting changes in annual hydropower generation using regional runoff data: An assessment of the United States federal hydropower plants

    SciTech Connect

    Kao, Shih -Chieh; Sale, Michael J.; Ashfaq, Moetasim; Uria Martinez, Rocio; Kaiser, Dale Patrick; Wei, Yaxing; Diffenbaugh, Noah S.

    2014-12-18

    Federal hydropower plants account for approximately half of installed US conventional hydropower capacity, and are an important part of the national renewable energy portfolio. Utilizing the strong linear relationship between the US Geological Survey WaterWatch runoff and annual hydropower generation, a runoff-based assessment approach is introduced in this study to project changes in annual and regional hydropower generation in multiple power marketing areas. Future climate scenarios are developed with a series of global and regional climate models, and the model output is bias-corrected to be consistent with observed data for the recent past. Using this approach, the median decrease in annual generation at federal projects is projected to be less than –2 TWh, with an estimated ensemble uncertainty of ±9 TWh. Although these estimates are similar to the recently observed variability in annual hydropower generation, and may therefore appear to be manageable, significantly seasonal runoff changes are projected and it may pose significant challenges in water systems with higher limits on reservoir storage and operational flexibility. Lastly, future assessments will be improved by incorporating next-generation climate models, by closer examination of extreme events and longer-term change, and by addressing the interactions among hydropower and other water uses.

  15. Large capacity, multi-fuel, and high temperature working fluid heaters to optimize CSP plant cost, complexity and annual generation

    NASA Astrophysics Data System (ADS)

    Peterseim, J. H.; Viscuso, L.; Hellwig, U.; McIntyre, P.

    2016-05-01

    This paper analyses the potential to optimize high temperature fluid back-up systems for concentrating solar power (CSP) plants by investigating the cost impact of component capacity and the impact of using multiple fuels on annual generation. Until now back-up heaters have been limited to 20MWth capacity but larger units have been realised in other industries. Installing larger units yields economy-of-scale benefits through improved manufacturing, optimised transport, and minimized on-site installation work. Halving the number of back-up boilers can yield cost reduction of 23% while minimizing plant complexity and on-site construction risk. However, to achieve these benefits it is important to adapt the back-up heaters to the plant's requirements (load change, capacity, minimum load, etc.) and design for manufacture, transport and assembly. Despite the fact that biomass availability is decreasing with increasing direct normal irradiance (DNI), some biomass is available in areas suitable for CSP plants. The use of these biomass resources is beneficial to maximise annual renewable energy generation, substitute natural gas, and use locally/seasonally available biomass resources that may not be used otherwise. Even small biomass quantities of only 50,000 t/a can increase the capacity factor of a 50MWe parabolic trough plant with 7h thermal energy storage from 40 to 49%. This is a valuable increase and such a concept is suitable for new plants and retrofit applications. However, similar to the capacity optimisation of back-up heaters, various design criteria have to be considered to ensure a successful project.

  16. Genetic differentiation among Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) populations living on different host plants.

    PubMed

    Rosas-García, Ninfa M; Sarmiento-Benavides, Sandra L; Villegas-Mendoza, Jesús M; Hernández-Delgado, Sanjuana; Mayek-Pérez, Netzahualcoyotl

    2010-06-01

    The pink hibiscus mealybug Maconellicoccus hirsutus (Green) is a dangerous pest that damages a wide variety of agricultural, horticultural, and forestry crops. Amplified fragment length polymorphism (AFLP) fingerprints were used to characterize the genetic variation of 11 M. hirsutus populations infesting three plant species in Nayarit, Mexico. Analysis was carried out using four primers combinations, producing 590 polymorphic bands. Cluster analysis, as well as bootstrap dendrogram and nonmetric multidimensional scaling analysis, grouped M. hirsutus populations according to their host plant. The estimated F(ST) values indicated a high differentiation in M. hirsutus populations among the three host plant species. These results were also supported by a Bayesian analysis, which indicated a population clustering robustness according to their host plant. Genetic variation among populations is not caused by geographic distances, as shown by a Mantel test.

  17. Annual survival and recruitment in a Ruby-throated Hummingbird population, excluding the effect of transient individuals

    USGS Publications Warehouse

    Hilton, B.; Miller, M.W.

    2003-01-01

    We estimated annual apparent survival, recruitment, and rate of population growth of breeding Ruby-throated Hummingbirds (Archilochus colubris), while controlling for transients, by using 18 years of capture-mark-recapture data collected during 1984-2001 at Hilton Pond Center for Piedmont Natural History near York, South Carolina. Resident males had lower apparent survival (0.30 +/- 0.05 SE) than females (0.43 +/- 0.04). Estimates of apparent survival did not differ by age. Point estimates suggested that newly banded males were less likely than females to be residents, but standard errors of these estimates overlapped (males: 0.60 +/- 0.14 SE; females: 0.67 +/- 0.09). Estimated female recruitment was 0.60 +/- 0.06 SE, meaning that 60% of adult females present in any given year had entered the population during the previous year. Our estimate for rate of change indicated the population of female hummingbirds was stable during the study period (1.04 +/- 0.04 SE). We suggest an annual goal of greater than or equal to 64 adult females and greater than or equal to 64 immature females released per banding area to enable rigorous future tests for effects of covariates on population dynamics. Development of a broader cooperating network of hummingbird banders in eastern North America could allow tests for regional or metapopulation dynamics in this species.

  18. The causes of selection on flowering time through male fitness in a hermaphroditic annual plant.

    PubMed

    Austen, Emily J; Weis, Arthur E

    2016-01-01

    Flowering is a key life-history event whose timing almost certainly affects both male and female fitness, but tests of selection on flowering time through male fitness are few. Such selection may arise from direct effects of flowering time, and indirect effects through covariance between flowering time and the environment experienced during reproduction. To isolate these intrinsically correlated associations, we staggered planting dates of Brassica rapa families with known flowering times, creating populations in which age at flowering (i.e., flowering time genotype) and Julian date of flowering (i.e., flowering time environment) were positively, negatively, or uncorrelated. Genetic paternity analysis revealed that male fitness was not strongly influenced by seasonal environmental changes. Instead, when age and date were uncorrelated, selection through male fitness strongly favored young age at flowering. Strategic sampling offspring for paternity analysis rejected covariance between sire age at flowering and dam quality as the cause of this selection. Results instead suggest a negative association between age at flowering and pollen competitive ability. The manipulation also revealed that, at least in B. rapa, the often-observed correlation between flowering time and flowering duration is environmental, not genetic, in origin. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  19. The demographic consequences of mutualism: ants increase host-plant fruit production but not population growth.

    PubMed

    Ford, Kevin R; Ness, Joshua H; Bronstein, Judith L; Morris, William F

    2015-10-01

    The impact of mutualists on a partner's demography depends on how they affect the partner's multiple vital rates and how those vital rates, in turn, affect population growth. However, mutualism studies rarely measure effects on multiple vital rates or integrate them to assess the ultimate impact on population growth. We used vital rate data, population models and simulations of long-term population dynamics to quantify the demographic impact of a guild of ant species on the plant Ferocactus wislizeni. The ants feed at the plant's extrafloral nectaries and attack herbivores attempting to consume reproductive organs. Ant-guarded plants produced significantly more fruit, but ants had no significant effect on individual growth or survival. After integrating ant effects across these vital rates, we found that projected population growth was not significantly different between unguarded and ant-guarded plants because population growth was only weakly influenced by differences in fruit production (though strongly influenced by differences in individual growth and survival). However, simulations showed that ants could positively affect long-term plant population dynamics through services provided during rare but important events (herbivore outbreaks that reduce survival or years of high seedling recruitment associated with abundant precipitation). Thus, in this seemingly clear example of mutualism, the interaction may actually yield no clear benefit to plant population growth, or if it does, may only do so through the actions of the ants during rare events. These insights demonstrate the value of taking a demographic approach to studying the consequences of mutualism.

  20. Molecular taxonomic analysis of the plant associations of adult pollen beetles (Nitidulidae: Meligethinae), and the population structure of Brassicogethes aeneus.

    PubMed

    Ouvrard, Pierre; Hicks, Damien M; Mouland, Molly; Nicholls, James A; Baldock, Katherine C R; Goddard, Mark A; Kunin, William E; Potts, Simon G; Thieme, Thomas; Veromann, Eve; Stone, Graham N

    2016-12-01

    Pollen beetles (Nitidulidae: Meligethinae) are among the most abundant flower-visiting insects in Europe. While some species damage millions of hectares of crops annually, the biology of many species is little known. We assessed the utility of a 797 base pair fragment of the cytochrome oxidase 1 gene to resolve molecular operational taxonomic units (MOTUs) in 750 adult pollen beetles sampled from flowers of 63 plant species sampled across the UK and continental Europe. We used the same locus to analyse region-scale patterns in population structure and demography in an economically important pest, Brassicogethes aeneus. We identified 44 Meligethinae at ∼2% divergence, 35 of which contained published sequences. A few specimens could not be identified because the MOTUs containing them included published sequences for multiple Linnaean species, suggesting either retention of ancestral haplotype polymorphism or identification errors in published sequences. Over 90% of UK specimens were identifiable as B. aeneus. Plant associations of adult B. aeneus were found to be far wider taxonomically than for their larvae. UK B. aeneus populations showed contrasting affiliations between the north (most similar to Scandinavia and the Baltic) and south (most similar to western continental Europe), with strong signatures of population growth in the south.

  1. Ability of matrix models to explain the past and predict the future of plant populations.

    PubMed

    Crone, Elizabeth E; Ellis, Martha M; Morris, William F; Stanley, Amanda; Bell, Timothy; Bierzychudek, Paulette; Ehrlén, Johan; Kaye, Thomas N; Knight, Tiffany M; Lesica, Peter; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F; Ticktin, Tamara; Valverde, Teresa; Williams, Jennifer L; Doak, Daniel F; Ganesan, Rengaian; McEachern, Kathyrn; Thorpe, Andrea S; Menges, Eric S

    2013-10-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts' 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data-collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk-averse decisions than to expect precise forecasts from models. © 2013 Society for Conservation Biology.

  2. Ability of matrix models to explain the past and predict the future of plant populations.

    USGS Publications Warehouse

    McEachern, Kathryn; Crone, Elizabeth E.; Ellis, Martha M.; Morris, William F.; Stanley, Amanda; Bell, Timothy; Bierzychudek, Paulette; Ehrlen, Johan; Kaye, Thomas N.; Knight, Tiffany M.; Lesica, Peter; Oostermeijer, Gerard; Quintana-Ascencio, Pedro F.; Ticktin, Tamara; Valverde, Teresa; Williams, Jennifer I.; Doak, Daniel F.; Ganesan, Rengaian; Thorpe, Andrea S.; Menges, Eric S.

    2013-01-01

    Uncertainty associated with ecological forecasts has long been recognized, but forecast accuracy is rarely quantified. We evaluated how well data on 82 populations of 20 species of plants spanning 3 continents explained and predicted plant population dynamics. We parameterized stage-based matrix models with demographic data from individually marked plants and determined how well these models forecast population sizes observed at least 5 years into the future. Simple demographic models forecasted population dynamics poorly; only 40% of observed population sizes fell within our forecasts' 95% confidence limits. However, these models explained population dynamics during the years in which data were collected; observed changes in population size during the data-collection period were strongly positively correlated with population growth rate. Thus, these models are at least a sound way to quantify population status. Poor forecasts were not associated with the number of individual plants or years of data. We tested whether vital rates were density dependent and found both positive and negative density dependence. However, density dependence was not associated with forecast error. Forecast error was significantly associated with environmental differences between the data collection and forecast periods. To forecast population fates, more detailed models, such as those that project how environments are likely to change and how these changes will affect population dynamics, may be needed. Such detailed models are not always feasible. Thus, it may be wiser to make risk-averse decisions than to expect precise forecasts from models.

  3. The effects of invertebrate herbivores on plant population growth: a meta-regression analysis.

    PubMed

    Katz, Daniel S W

    2016-09-01

    Over the last two decades, an increasing number of studies have quantified the effects of herbivory on plant populations using stage-structured population models and integral projection models, allowing for the calculation of plant population growth rates (λ) with and without herbivory. In this paper, I assembled 29 studies and conducted a meta-regression to determine the importance of invertebrate herbivores to population growth rates (λ) while accounting for missing data. I found that invertebrate herbivory often induced important reductions in plant population growth rates (with herbivory, λ was 1.08 ± 0.36; without herbivory, λ was 1.28 ± 0.58). This relationship tended to be weaker for seed predation than for other types of herbivory, except when seed predation rates were very high. Even so, the amount by which studies reduced herbivory was a poor predictor of differences in population growth rates-which strongly cautions against using measured herbivory rates as a proxy for the impact of herbivores. Herbivory reduced plant population growth rates significantly more when potential growth rates were high, which helps to explain why there was less variation in actual population growth rates than in potential population growth rates. The synthesis of these studies also shows the need for future studies to report variance in estimates of λ and to quantify how λ varies as a function of plant density.

  4. Mixed populations and annual flood frequency estimates in the western United States: The role of atmospheric rivers

    NASA Astrophysics Data System (ADS)

    Barth, Nancy A.; Villarini, Gabriele; Nayak, Munir A.; White, Kathleen

    2017-01-01

    The Bulletin 17B framework assumes that the annual peak flow data included in a flood frequency analysis are from a homogeneous population. However, flood frequency analysis over the western United States is complicated by annual peak flow records that frequently contain annual flows generated from distinctly different flood generating mechanisms. These flood series contain multiple zero flows and/or potentially influential low floods (PILFs) that substantially deviate from the overall pattern in the data. Moreover, they often also contain extreme flood events representing different hydrometeorologic agents. Among the different flood generating mechanisms, atmospheric rivers (ARs) are responsible for large, regional-scale floods. The spatial and fractional contribution of ARs in annual peak flow data is examined based on 1375 long-term U.S. Geological Survey (USGS) streamgage sites with at least 30 years of data. Six main areas in which flooding is impacted by ARs at varying degrees were found throughout the western United States. The Pacific Northwest and the northern California coast have the highest fraction of AR-generated peaks (˜80-100%), while eastern Montana, Wyoming, Utah, Colorado, and New Mexico have nearly no impacts from ARs. The individual regions of the central Columbia River Basin in the Pacific Northwest, the Sierra Nevada, the central and southern California coast, and central Arizona all show a mixture of 30-70% AR-generated flood peaks. Analyses related to the largest flood peaks on record and to the estimated annual exceedance probabilities highlight the strong impact of ARs on flood hydrology in this region, together with marked regional differences.

  5. Changes in Plant-Parasitic Nematode Populations in Pineapple Fields Following Inter-Cycle Cover Crops

    PubMed Central

    Ko, M. P.; Schmitt, D. P.

    1996-01-01

    The use of plant-covers oat (Arena sativa L.), rhodesgrass (Chloris gayana Kunth), soybean (Glycine max [L.] Merr.), and marigold (Tagetes patula L.) during pineapple inter-cycle planting periods was investigated at two sites (Kunia and Whitmore, Oahu, HI) as a potential means to reduce population densities of Rotylenchulus reniformis, Helicotylenchus dihystera, and Paratylenchus spp. Clean fallow and fallow covered with pineapple-plant residues (mulch) were the controls without plant-cover. Regardless of treatments, population densities of R. reniformis declined with time at both sites to low residue levels by the end of the 6-month period. Treatment means of R. reniformis population densities in the plant-cover treatments were lower than the controls' (P = 0.05). The plant-cover treatments also effected higher rates of R. reniformis population decline at both sites during the period, being 2.0 to 2.2 times that of the mulch control and 1.2 to 1.4 times that of the fallow control. Plant-covers' effect on H. dihystera during the same period at both sites was variable, resulting in decreased, unchanged, or increased population densities. The change was especially obvious in the oat-cover treatment, where H. dihystera population densities increased 9 to 15-fold at both sites. Population of Paratylenchus spp. was absent or present at low levels at the sites throughout the period. Biological activities antagonistic to R. reniformis at Kunia were estimated at the end of 6 months by comparing the extent of nematode's reproduction (on cowpea seedlings) in the treatment soils that had been subjected to autoclaving or freezing temperature. Although higher indices of antagonistic activities were observed in soils with prior plant-cover treatments than in soils from the controls, none of the treatments resulted in conferring soils the increased ability to suppress re-introduced R. reniformis populations or enhance subsequent pineapple-plant growth. PMID:19277173

  6. Microbial Population and Community Dynamics on Plant Roots and Their Feedbacks on Plant Communities

    PubMed Central

    Bever, James D.; Platt, Thomas G.; Morton, Elise R.

    2012-01-01

    The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology. PMID:22726216

  7. Microbial population and community dynamics on plant roots and their feedbacks on plant communities.

    PubMed

    Bever, James D; Platt, Thomas G; Morton, Elise R

    2012-01-01

    The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology.

  8. Chemical defenses (glucosinolates) of native and invasive populations of the range expanding invasive plant Rorippa austriaca.

    PubMed

    Huberty, Martine; Tielbörger, Katja; Harvey, Jeffrey A; Müller, Caroline; Macel, Mirka

    2014-04-01

    Due to global warming, species are expanding their range to higher latitudes. Some range expanding plants have become invasive in their new range. The Evolution of Increased Competitive Ability (EICA) hypothesis and the Shifting Defense Hypothesis (SDH) predict altered selection on plant defenses in the introduced range of invasive plants due to changes in herbivore pressures and communities. Here, we investigated chemical defenses (glucosinolates) of five native and seven invasive populations of the Eurasian invasive range expanding plant, Rorippa austriaca. Further, we studied feeding preferences of a generalist and a specialist herbivore among the populations. We detected eight glucosinolates in the leaves of R. austriaca. 8-Methylsulfinyloctyl glucosinolate was the most abundant glucosinolate in all plants. There were no overall differences between native and invasive plants in concentrations of glucosinolates. However, concentrations among populations within each range differed significantly. Feeding preference between the populations by a generalist herbivore was negatively correlated with glucosinolate concentrations. Feeding by a specialist did not differ between the populations and was not correlated with glucosinolates. Possibly, local differences in herbivore communities within each range may explain the differences in concentrations of glucosinolates among populations. Little support for the predictions of the EICA hypothesis or the SDH was found for the glucosinolate defenses of the studied native and invasive R. austriaca populations.

  9. Annual radiological environmental operating report: Browns Ferry Nuclear Plant, 1992. Operations Services/Technical Programs

    SciTech Connect

    Not Available

    1993-04-01

    This report describes the environmental radiological monitoring program conducted by TVA in the vicinity of Browns Ferry Nuclear Plant (BFN) in 1992. The program includes the collection of samples from the environment and the determination of the concentrations of radioactive materials in the samples. Samples are taken from stations in the general area of the plant and from areas not influenced by plant operations. Station locations are selected after careful consideration of the weather patterns and projected radiation doses to the various areas around the plant. Material sampled includes air, water, milk, foods, vegetation, soil, fish, sediment, and direct radiation levels. Results from stations near the plant are compared with concentrations from control stations and with preoperational measurements to determine potential impacts of plant operations. Small amounts of Co-60 and Cs-134 were found in sediment samples downstream from the plant. This activity in stream sediment would result in no measurable increase over background in the dose to the general public.

  10. 77 FR 58510 - Proposed Information Collection; Comment Request; Current Population Survey (CPS), Annual Social...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ...; ] DEPARTMENT OF COMMERCE Census Bureau Proposed Information Collection; Comment Request; Current Population... whole and selected population groups of interest. Government planners and researchers use these data to..., recovery, and so on, and their differential effects on various population groups. A prime statistic of...

  11. Alcoa World Alumina: Plant-Wide Assessment at Arkansas Operations Reveals More than$900,000 in Potential Annual Savings

    SciTech Connect

    Not Available

    2003-07-01

    The plant-wide energy-efficiency assessment performed in 2001 at the Alcoa World Alumina Arkansas Operations in Bauxite, Arkansas, identified seven opportunities to save energy and reduce costs. By implementing five of these improvements, the facility can save 15,100 million British thermal units per year in natural gas and 8.76 million kilowatt-hours per year in electricity. This translates into approximate annual savings of$925,300 in direct energy costs and non-fuel operating and maintenance costs. The required capital investment is estimated at$271,200. The average payback period for all five projects would be approximately 8 months.

  12. Alcoa World Alumina: Plant Wide Assessment at Arkansas Operation Reveals More than $900,000 in Potential Annual Savings

    SciTech Connect

    2003-07-01

    The plant-wide energy-efficiency assessment performed in 2001 at the Alcoa World Alumina Arkansas Operations in Bauxite, Arkansas, identified seven opportunities to save energy and reduce costs. By implementing five of these improvements, the facility can save 15,100 million British thermal units per year in natural gas and 8.76 million kilowatt-hours per year in electricity. This translates into approximate annual savings of $925,300 in direct energy costs and non-fuel operating and maintenance costs. The required capital investment is estimated at $271,200. The average payback period for all five projects would be approximately 8 months.

  13. Influence of Nonhost Plants on Population Decline of Rotylenchulus reniformis

    PubMed Central

    Caswell, E. P.; DeFrank, J.; Apt, W. J.; Tang, C. S.

    1991-01-01

    The influence of Chloris gayana, Crotalaria juncea, Digitaria decumbens, Tagetes patula, and a chitin-based soil amendment on Hawaiian populations of Rotylenchulus reniformis was examined. Chloris gayana was a nonhost for R. reniformis. The nematode did not penetrate the roots, and in greenhouse and field experiments, C. gayana reduced reniform nematode numbers at least as well as fallow. Tagetes patula was a poor host for reniform nematode and reduced reniform nematode numbers in soil better than did fallow. Crotalaria juncea was a poor host for R. reniformis, and only a small fraction of the nematode population penetrated the roots. Crotalaria juncea and D. decumbens reduced reniform nematode populations at least as well as fallow. A chitin-based soil amendment, applied at 2.24 t/ha to fallow soil, did not affect the population decline of reniform nematode. PMID:19283098

  14. The influence of the annual invasive plant, Impatiens glandulifera, on the sediment dynamics of inland watercourses in temperate regions

    NASA Astrophysics Data System (ADS)

    Dalvi, Shrutika; Greenwood, Philip

    2016-04-01

    Impatiens glandulifera (Common English Name - Himalayan Balsam) is a non native annual and highly invasive plant that was introduced into parts of Europe from the Himalaya during the nineteenth century as a colourful adornment to parks and gardens. This Plant colonises areas along the river banks, preferably wet, depositional sites, and displaces natural vegetation. The plant is killed by cold weather. The leaves area of riverbank previously occupied by the plant extremely vulnerable to soil erosion until new plant germinates in the following spring. Research work undertaken in the northwest Switzerland and the soutwestern United Kingdom established s link between accelerated soil erosion caused by Impatiens glandulifera and its detrimental impact on native biodiversity of riparian zone of river catchment area. This study focueses on the potential impact of such erosion on sediment quality. A priory reasoning suggests that the preference of Impatiens glandulifera on young depsotional sites near watercourses affects sediment quality. In this study, the results of a soil quality analysis along Impatiens glandulifera-contaminated river banks is presented. Soil physical and chemical properties are compared to non-affected sites to assess the potential impact of preferential erosion on water quality. In addtiion, soil surface profile (SSP) measuring based on by erosion pins, a micro profile bridge and a digital calliper at different selected locations along the riparian zone of river catchment area is used to determine erosion rates and determine sediment transfer from the riparian zone into the rivers.

  15. Research progress of plant population genomics based on high-throughput sequencing.

    PubMed

    Yunsheng, Wang

    2016-08-01

    Population genomics, a new paradigm for population genetics, combine the concepts and techniques of genomics with the theoretical system of population genetics and improve our understanding of microevolution through identification of site-specific effect and genome-wide effects using genome-wide polymorphic sites genotypeing. With the appearance and improvement of the next generation high-throughput sequencing technology, the numbers of plant species with complete genome sequences increased rapidly and large scale resequencing has also been carried out in recent years. Parallel sequencing has also been done in some plant species without complete genome sequences. These studies have greatly promoted the development of population genomics and deepened our understanding of the genetic diversity, level of linking disequilibium, selection effect, demographical history and molecular mechanism of complex traits of relevant plant population at a genomic level. In this review, I briely introduced the concept and research methods of population genomics and summarized the research progress of plant population genomics based on high-throughput sequencing. I also discussed the prospect as well as existing problems of plant population genomics in order to provide references for related studies.

  16. Plant litter effects on soil nutrient availability and vegetation dynamics: changes that occur when annual grasses invade shrub-steppe communities

    Treesearch

    Sheel Bansal; Roger L. Sheley; Bob Blank; Edward A. Vasquez

    2014-01-01

    Changes in the quantity and quality of plant litter occur in many ecosystems as they are invaded by exotic species, which impact soil nutrient cycling and plant community composition. Such changes in sagebrush-steppe communities are occurring with invasion of annual grasses (AG) into a perennial grass (PG) dominated system. We conducted a 5-year litter manipulation...

  17. Characterization of annual disease progression of multiple sclerosis patients: A population-based study.

    PubMed

    Freilich, Jonatan; Manouchehrinia, Ali; Trusheim, Mark; Baird, Lynn G; Desbiens, Sophie; Berndt, Ernst; Hillert, Jan

    2017-05-01

    Previous research characterizing factors influencing multiple sclerosis (MS) disease progression has typically been based on time to disease milestones (Kaplan-Meier, Cox hazard regression, etc.). A limitation of these methods is the handling of the often large groups of patients not reaching the milestone. To characterize clinical factors influencing MS disease progression as annual transitions from each Expanded Disability Status Scale (EDSS). The annual progression of 11,964 patients from the Swedish MS Registry was analysed with 10 multinomial logistic regressions, that is, one for transition from each full EDSS with explanatory variables age, sex, age at onset, time in current EDSS, highest prior EDSS, MS course and treatment. All factors (except sex) investigated had statistically significant impacts on transitions from at least one EDSS. However, significance and size of the effect are dependent on the EDSS state of the patient. Greater age, longer time in a state, highest prior EDSS, having progressive MS and treatment had significant impacts, whereas age at onset had minor impact. Our study confirms that established factors associated with MS disease worsening in time to disease milestones also have impacts on annual progression. This approach adds granularity to what EDSS these factors have an influence.

  18. Regulation of polyamine synthesis in plants. Annual progress report, July 1, 1992--June 30, 1993

    SciTech Connect

    Malmberg, R.L.

    1995-07-01

    After isolation of a cDNA clone for the plant ARGdc, this research focused on unusual post-translational modifications occuring in a arginine decarboxylase cDNA clone in oats. A novel regulatory mechanism for polyamines was explored and an attempt was made to characterize it. A plant ornithine decarboxylase cDNA was identified in Arabidopsis. Further work remains on the mechanisms of polyamine regulation and function in plants.

  19. Population dynamics of filamentous bacteria in Danish wastewater treatment plants with nutrient removal.

    PubMed

    Mielczarek, Artur Tomasz; Kragelund, Caroline; Eriksen, Poul Svante; Nielsen, Per Halkjær

    2012-08-01

    Bulking and foaming are two frequently occurring operational problems in activated sludge wastewater treatment plants, and these problems are mainly associated with excessive growth of filamentous bacteria. In this study, a comprehensive investigation of the identity and population dynamics of filamentous bacteria in 28 Danish municipal treatment plants with nutrient removal has been carried out over three years. Fluorescence in situ hybridization was applied to quantify more than twenty probe-defined populations of filamentous bacteria that in total constituted a large fraction of the entire microbial community, on average 24%. Despite the majority being present within the flocs, they occasionally caused settling problems in most of the plants. A low diversity of probe-defined filamentous bacteria was found in the plants with Microthrix and various species belonging to phylum Chloroflexi (e.g., type 0803 and type 0092) as the most abundant. Few other filamentous probe-defined species were found revealing a large similarity between the filamentous populations in the plants investigated. The composition of filamentous populations was stable in each plant with only minor changes in relative abundances observed during the three-year study period. The relative composition of the different species was unique to each plant giving a characteristic "fingerprint". Comprehensive statistical analyses of the presence and abundance of the filamentous organisms did not reveal many correlations with a particular plant design or process parameter.

  20. Occupational hazard evaluation of working population in a select automotive industrial plant.

    PubMed

    Wójcik, Alicja; Borzecki, Zdzisław; Kowalska, Edyta; Borzecki, Andrzej

    2004-01-01

    The research was conducted in the selected vehicle industry plant. Work conditions were assessed on the assembly line by measuring chemical and physical factors. Exposure to noise in the investigated plant exceeded the values of permissible standards. The pollution on the posts did not exceed the standards except singular concentrations. While assessing the values of chemical factors concentration, no toxicological danger was revealed in the investigated population. The work conditions of the investigated plant did not create the danger of professional diseases.

  1. Weirton Steel: Mill Identifies $1.4 Million in Annual Savings Following Plant-Wide Energy-Efficiency Assessment

    SciTech Connect

    2004-01-01

    The Weirton Steel Corporation performed a plant-wide energy assessment of its steel mill plant in Weirton, West Virginia. Based on the assessment results, the company found strong economic justification for six projects that would reduce the use of fossil fuel, electrical energy, and water. All of the projects would save fossil fuel either for heating steam or firing the furnace. This savings totals 108,300 million British thermal units (MMBtu) annually or $1.27 million. Other yearly savings include 119 million gallons of water ($87,110) and 84,000 kilowatt-hours (kWh) or $3,357 of electrical energy. All of the projects could be applied to other steel mills and possibly other industries using steam processes and furnaces.

  2. Perennial grass dominance: creating a resilient plant community in an exotic annual grass invaded rangeland

    USDA-ARS?s Scientific Manuscript database

    Millions of hectares of western rangelands have been invaded by the exotic and invasive annual grass, cheatgrass (Bromus tectorum). Cheatgrass provides a fine-textured, early maturing fuel that has increased the chance, rate, spread and season of wildfire to public and private lands throughout the ...

  3. Managing soil nitrogen to restore annual grass-infested plant communities: Effective strategy or incomplete framework?

    Treesearch

    J. J. James; R. E. Drenovsky; T. A. Monaco; M. J. Rinella

    2011-01-01

    Theoretical and empirical work has established a positive relationship between resource availability and habitat invasibility. For nonnative invasive annual grasses, similar to other invasive species, invader success has been tied most often to increased nitrogen (N) availability. These observations have led to the logical assumption that managing soils for low N...

  4. Mixed populations and annual flood frequency estimates in the western United States: The role of atmospheric rivers

    NASA Astrophysics Data System (ADS)

    Barth, N. A.; Villarini, G.; Nayak, M. A.

    2015-12-01

    More than 30 years have passed since the authors of Bulletin 17B recommended additional studies be performed: (i) to test whether the proper distribution and fitting procedures are different depending on watersheds and hydrometeorological conditions and (ii) to identify mixed distributions. The Bulletin 17B framework assumes that the annual peak flow data included in a flood frequency analysis are from a homogeneous population. However, flood frequency analysis over the western United States is complicated by annual peak flow records that frequently contain annual flows generated from distinctly different flood generating mechanisms. In particular, these flood series contain multiple zero flows and/or potentially influential low floods that substantially deviate from the overall pattern, as well as extreme flood events representing different hydrometeorologic events. Among the different flood generating mechanisms, atmospheric rivers are responsible for large, regional scale floods. This study examines the role played by atmospheric rivers in flood frequency analyses across the western United States. Results are based on U.S. Geological Survey streamflow-gaging stations with a record of at least 30 years, and highlight the areas of the western United States that are most affected by these events.

  5. Population differentiation for germination and early seedling root growth traits under saline conditions in the annual legume Medicago truncatula (Fabaceae).

    PubMed

    Cordeiro, Matilde A; Moriuchi, Ken S; Fotinos, Tonya D; Miller, Kelsey E; Nuzhdin, Sergey V; von Wettberg, Eric J; Cook, Douglas R

    2014-03-01

    Seedling establishment and survival are highly sensitive to soil salinity and plants that evolved in saline environments are likely to express traits that increase fitness in those environments. Such traits are of ecological interest and they may have practical value for improving salt tolerance in cultivated species. We examined responses to soil salinity and tested potential mechanisms of salt tolerance in Medicago truncatula, using genotypes that originated from natural populations occurring on saline and nonsaline soils. Germination and seedling responses were quantified and compared between saline and nonsaline origin genotypes. Germination treatments included a range of sodium chloride (NaCl) concentrations in both offspring and parental environments. Seedling treatments included NaCl, abscisic acid (ABA), and potassium chloride (KCl). Saline origin genotypes displayed greater salinity tolerance for germination and seedling traits relative to nonsaline origin genotypes. We observed population specific differences for the effects of salinity on time to germination and for the impact of parental environment on germination rates. ABA and NaCl treatments had similar negative effects on root growth, although relative sensitivities differed, with saline population less sensitive to NaCl and more sensitive to ABA compared to their nonsaline counterparts. We report population differentiation for germination and seedling growth traits under saline conditions among populations derived from saline and nonsaline environments. These observations are consistent with a syndrome of adaptations for salinity tolerance during early plant development, including traits that are common among saline environments and those that are idiosyncratic to local populations.

  6. Population density and feeding duration of cabbage looper larvae on tomato plants alter the levels of plant volatile emissions.

    PubMed

    Miresmailli, Saber; Gries, Regine; Gries, Gerhard; Zamar, Ruben H; Isman, Murray B

    2012-01-01

    As part of their indirect defense, plants under herbivore attack release volatile chemicals that attract natural enemies of the herbivore. This is a very well-documented phenomenon. However, relatively few studies have investigated the response of plants to different population levels of herbivores and their feeding duration. Working with larvae of the cabbage looper, Trichoplusia ni (Hübner), and tomato plants, Lycopersicon esculentum Mill cv. clarence, and using an ultrafast gas chromatograph (the zNose™) for volatile analyses, the authors studied the effect of larval density and feeding duration on levels of plant volatile emissions. Intense herbivory caused higher emission levels of the herbivore-induced plant volatiles (HIPVs) (Z)-3-hexenyl acetate, (E)-β-ocimene and β-caryophyllene than those caused by moderate herbivory. When herbivory had ceased following 12-24 h of larval feeding, plants kept releasing HIPVs at a high level for a longer period of time than they did following only 6 h of larval feeding. The plants' slow adjustment in their volatile emissions following prolonged larval feeding might be strategic, as such feeding is more likely to have ceased just temporarily. This information may help in the development of a pest monitoring system that is based on herbivore-induced plant volatiles. Copyright © 2011 Society of Chemical Industry.

  7. Composition of the phyllospheric microbial populations on vegetable plants with different glucosinolate and carotenoid compositions.

    PubMed

    Ruppel, Silke; Krumbein, Angelika; Schreiner, Monika

    2008-08-01

    The plant phyllosphere is intensely colonized by a complex and highly diverse microbial population and shows pronounced plant-species-specific differences. The mechanisms and influencing factors determining whether and in which density microorganisms colonize plant phyllosphere tissues are not yet fully understood. One of the key influencing factors is thought to be phytochemical concentration and composition. Therefore, correlations between various concentrations of individual glucosinolates and carotenoids in four different plant species-Brassica juncea, Brassica campestris, Cichorium endivia, and Spinacea oleracea-and the phyllospheric bacterial population size associated with the aerial parts of the same plants were analyzed. The concentration of various individual glucosinolates and carotenoids were measured using high-performance liquid chromatography. The phyllospheric bacterial population size including both nonculturable and culturable organisms was assessed using quantitative real-time polymerase chain reaction, and the physiological profile of the culturable microbial community was analyzed using the Biolog system. Results show significant differences between plant species in both concentration and composition of secondary metabolites, bacterial population size, and microbial community composition in three consecutively performed experiments. An interesting and underlying trend was that bacterial density was positively correlated to concentrations of beta-carotene in the plant phyllosphere of the four plant species examined. Likewise, the alkenyl glucosinolates, 2-propenyl, 3-butenyl, and 4-pentenyl, concentrations were positively correlated to the bacterial population density, whereas the aromatic glucosinolate 2-phenylethyl showed a negative correlation to the phyllospheric bacterial population size. Thus, we report for the first time the relationship between individual glucosinolate and carotenoid concentrations and the phyllospheric bacterial

  8. Scrophularia arguta, a widespread annual plant in the Canary Islands: a single recent colonization event or a more complex phylogeographic pattern?

    PubMed

    Valtueña, Francisco Javier; López, Josefa; Álvarez, Juan; Rodríguez-Riaño, Tomás; Ortega-Olivencia, Ana

    2016-07-01

    Many studies have addressed evolution and phylogeography of plant taxa in oceanic islands, but have primarily focused on endemics because of the assumption that in widespread taxa the absence of morphological differentiation between island and mainland populations is due to recent colonization. In this paper, we studied the phylogeography of Scrophularia arguta, a widespread annual species, in an attempt to determine the number and spatiotemporal origins of dispersal events to Canary Islands. Four different regions, ITS and ETS from nDNA and psbA-trnH and psbJ-petA from cpDNA, were used to date divergence events within S. arguta lineages and determine the phylogenetic relationships among populations. A haplotype network was obtained to elucidate the phylogenetic relationships among haplotypes. Our results support an ancient origin of S. arguta (Miocene) with expansion and genetic differentiation in the Pliocene coinciding with the aridification of northern Africa and the formation of the Mediterranean climate. Indeed, results indicate for Canary Islands three different events of colonization, including two ancient events that probably happened in the Pliocene and have originated the genetically most divergent populations into this species and, interestingly, a recent third event of colonization of Gran Canaria from mainland instead from the closest islands (Tenerife or Fuerteventura). In spite of the great genetic divergence among populations, it has not implied any morphological variation. Our work highlights the importance of nonendemic species to the genetic richness and conservation of island flora and the significance of the island populations of widespread taxa in the global biodiversity.

  9. RADIATION EXPOSURE OF THE POPULATION FROM 222Rn AND OTHER NATURAL RADIONUCLIDES AROUND MOCHOVCE NUCLEAR POWER PLANT, SLOVAKIA.

    PubMed

    Bulko, Martin; Holý, Karol; Pohronská, Žofia; Mullerová, Monika; Böhm, Radoslav; Holá, Ol'ga

    2017-09-18

    In this article, the effective dose to the population from natural sources of ionizing radiation in the vicinity of Mochovce nuclear power plant in Slovakia is presented. All major contributions to the effective dose were taken into account, including the contributions from gamma radiation of soil and rocks, cosmic radiation, and indoor and outdoor radon and thoron. On the basis of recent indoor radon measurements in Slovak cities and publicly available data about radon concentration in the soil air, a roughly linear relationship was found between these variables. Consequently, the annual effective dose from indoor radon and thoron was conservatively estimated. For the area of interest, a map of conservatively estimated potential effective doses was created. For the villages in the vicinity of Mochovce, the conservatively estimated effective dose to the population from natural sources ranged from 5.4 to 14.6 mSv, which is four orders of magnitude higher than the contribution of radioactive discharges from Mochovce nuclear power plant. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Enhancement of nitrogen and phosphorus removal from eutrophic water by economic plant annual ryegrass (Lolium multiflorum) with ion implantation.

    PubMed

    Li, Miao; Sheng, Guo-ping; Wu, Yue-jin; Yu, Zeng-liang; Bañuelos, Gary S; Yu, Han-qing

    2014-01-01

    Severe eutrophication of surface water has been a major problem of increasing environmental concern worldwide. In the present study, economic plant annual ryegrass (Lolium multiflorum) was grown in floating mats as an economic plant-based treatment system to evaluate its potential after ion implantation for removing nutrients in simulated eutrophic water. The specific weight growth rate of L. multiflorum with ion implantation was significantly greater than that of the control, and the peroxidase, nitrate reductase, and acid phosphatase activities of the irradiated L. multiflorum were found to be greater than those plants without ion implantation. Higher total nitrogen (TN) and total phosphorus (TP) removal efficiencies were obtained for the L. multiflorum irradiated with 25 keV 5.2 × 10(16) N(+) ions/cm(2) and 30 keV 4.16 × 10(16) N(+) ions/cm(2), respectively (p < 0.05). Furthermore, the nitrogen and phosphorus contents in the plant biomass with ion implantation were also greater than those in the control and were positively correlated with TN and TP supplied. L. multiflorum itself was directly responsible for 39-49 and 47-58 % of the overall N and P removal in the experiment, respectively. The research results suggested that ion implantation could become a promising approach for increasing phytoremediation efficiency of nutrients from eutrophic water by L. multiflorum.

  11. Row Spacing and Plant Population Effects on Cotton Produced With or Without Irrigation

    USDA-ARS?s Scientific Manuscript database

    Field studies were conducted from 2006 through 2008 to evaluate the effects of twin-row spacings, populations, and irrigation on cotton (Gossypium hirsutum L.) lint yields. Twin row systems, consisting of twin 18-, 25- and 38-cm rows on a 1-m bed at populations of 111,000 and 148,000 plants/acre, w...

  12. Baselines to detect population stability of the threatened alpine plant Packera franciscana (Asteraceae)

    Treesearch

    James F. Fowler; Carolyn Hull Sieg; Shaula Hedwall

    2015-01-01

    Population size and density estimates have traditionally been acceptable ways to track species’ response to changing environments; however, species' population centroid elevation has recently been an equally important metric. Packera franciscana (Greene) W.A. Weber and A. Love (Asteraceae; San Francisco Peaks ragwort) is a single mountain endemic plant found only...

  13. Penicillium populations in dry-cured ham manufacturing plants.

    PubMed

    Battilani, Paola; Pietri, V Amedeo; Giorni, Paola; Formenti, Silvia; Bertuzzi, Terenzio; Toscani, Tania; Virgili, Roberta; Kozakiewicz, Zofia

    2007-04-01

    Seven ham manufacturing plants were sampled for 1 year to assess the mycoflora present in the air and on hams, with special attention given to potential mycotoxin producers. Temperature and relative humidity were recorded in the ripening rooms. Maturing rooms held hams from 2 to 3 through 6 to 7 ripening months, and aging rooms held hams for the following 6 to 7 months, until the 14-month ripening point, when they were ready for the market. Mean temperatures and relative humidities registered during the study were 14.9 degrees C and 62.4%, respectively, in maturing rooms and 16.3 degrees C and 57.6% in aging rooms. Aspergilli and penicillia, potential mycotoxin producers, were isolated in all the plants from the air and the ham. Aspergilli represented 5% of the isolates, while penicillia were largely dominant, with Penicillium nalgiovense being the most represented species (around 60% of the penicillia), followed by Penicillium nordicum, with 10 and 26% of the penicillia isolated, respectively, from the air or the ham. Ochratoxin A production ability, checked in vitro at 250C, was observed in 50% of the P. nordicum isolates obtained both from the air and the ham. Air and ham surface contamination by penicillia was greater in the ripening rooms, where higher temperatures were registered. A certain correlation was also observed between air and ham surface contamination. On the basis of this study, P. nordicum, the ochratoxin A producer that is notable on proteinaceous substrates, is normally present in ham manufacturing plants in Italy, even though not a dominant species. Further studies are necessary to clarify and ensure if dry-curing conditions minimize the potential risk of ochratoxin A formation in the product.

  14. Acephate resistance in populations of the tarnished plant bug (Heteroptera: Miridae) from the Mississippi River Delta.

    PubMed

    Snodgrass, G L; Gore, J; Abel, C A; Jackson, R

    2009-04-01

    A monitoring program that used a glass-vial bioassay to detect acephate resistance in populations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae), was carried out with weed-collected populations from 20 sites in the delta of Arkansas, Louisiana, and Mississippi. Additional results from field tests using recommended rates of formulated acephate in cotton showed that plant bug populations with resistance ratio (RR50) values > 3.0 for acephate (from the glass-vial bioassay) would be difficult to control in the field. Over a 4-yr-period from 2001 through 2004, only one population tested with the glass-vial bioassay was found with an RR50 value > 3.0 for acephate, but six populations having RR50 values > 3.0 were found in the delta in 2005. In fall 2005, an additional 10 populations from the hill region (the cotton growing areas outside the delta) were tested and four of these populations had RR50 values > 3.0. The number of populations with RR50 values > 3.0 increased to five of 10 and 18 of 20 in the hills and delta, respectively, in fall 2006. Laboratory tests using resistant populations found that resistance to acephate was not sex-linked and the alleles controlling the resistance were semidominant in nature. Because of the large increase in resistant populations and the nature of the resistance found in this study, along with control problems experienced by growers in 2006, entomologists in the mid-South strongly recommended that alternation of insecticide classes in field treatments for plant bug control be used by growers in 2007. This control strategy probably helped control plant bugs in the hills of MS where plant bug pressure was low in 2007, and only one population was found in the fall with an RR50 value > 3.0. Plant bug pressure was very high in many parts of the delta in 2007, and 15 of the 20 populations tested in the fall had RR50 values > 3.0. In one field test in cotton, a population with multiple resistance

  15. Evolution of Wheat streak mosaic virus: dynamics of population growth within plants may explain limited variation.

    PubMed

    French, Roy; Stenger, Drake C

    2003-01-01

    Like many other plant RNA viruses, Wheat streak mosaic virus (WSMV) sequence diversity within and among infected plants is low given the large number of virions produced. This may be explained by considering aspects of plant virus life history. Intracellular replication of RNA viruses is predominately linear, not exponential, which means that the rate at which mutations accumulate also is linear. Bottlenecks during systemic movement further limit diversity. Analysis of mixed infections with two WSMV isolates suggests that about four viral genomes participate in systemic invasion of each tiller. Low effective population size increases the role of stochastic processes on dynamics of plant virus population genetics and evolution. Despite low pair-wise diversity among isolates, the number of polymorphic sites within the U.S. population is about the same as between divergent strains or a sister species. Characteristics of polymorphism in the WSMV coat protein gene suggest that most variation appears neutral.

  16. Intra-annual growth and mortality of four Populus clones in pure and mixed plantings

    Treesearch

    Warren D. Devine; Constance A. Harrington; Dean S. DeBell

    2010-01-01

    Intra-annual growth rates were assessed during 3 years for four Populus clones grown in pure and mixed clonal stands at square spacings of 0.5, 1.0, and 1.5 m in western Washington, USA. Height growth rate peaked in August, except at the 0.5-m spacing where it peaked in July and June in years 2 and 3, respectively. Diameter growth rate generally...

  17. Radioactive materials released from nuclear power plants. Annual report 1989: Volume 10

    SciTech Connect

    Tichler, J.; Norden, K.; Congemi, J.

    1992-09-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1989 have been compiled and reported. The summary data for the years 1970 through 1988 are included for comparison. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1989 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  18. Radioactive materials released from nuclear power plants. Annual report 1991, Volume 12

    SciTech Connect

    Tichler, J.; Doty, K.; Congemi, J.

    1994-05-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1991 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1991 release data are summarized in tabular form. Data Covering specific radionuclides are summarized.

  19. Radioactive materials released from nuclear power plants. Volume 13, Annual report 1992

    SciTech Connect

    Tichler, J.; Doty, K.; Lucadamo, K.

    1995-08-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1992 have been compiled and reported. The summary data for the years 1973 through 1991 are included for comparison. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1992 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  20. Radioactive materials released from nuclear power plants. Volume 11: Annual report, 1990

    SciTech Connect

    Tichler, J.; Doty, K.; Congemi, J.

    1993-10-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1990 have been compiled and reported. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1990 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  1. Radioactive materials released from nuclear power plants: Annual report, 1993. Volume 14

    SciTech Connect

    Tichler, J.; Doty, K.; Lucadamo, K.

    1995-12-01

    Releases of radioactive materials in airborne and liquid effluents from commercial light water reactors during 1993 have been compiled and reported. The summary data for the years 1974 through 1992 are included for comparison. Data on solid waste shipments as well as selected operating information have been included. This report supplements earlier annual reports issued by the former Atomic Energy Commission and the Nuclear Regulatory Commission. The 1993 release data are summarized in tabular form. Data covering specific radionuclides are summarized.

  2. HyPEP-FY 07 Annual Report: A Hydrogen Production Plant Efficiency Calculation Program

    SciTech Connect

    Chang Oh

    2007-09-01

    The Very High Temperature Gas-Cooled Reactor (VHTR) coupled to the High Temperature Steam Electrolysis (HTSE) process is one of two reference integrated systems being investigated by the U.S. Department of Energy and Idaho National Laboratory for the production of hydrogen. In this concept the VHTR outlet temperature of 900 °C provides thermal energy and high efficiency electricity for the electrolysis of steam in the HTSE process. In the second reference system the Sulfur Iodine (SI) process is coupled to the VHTR to produce hydrogen thermochemically. In the HyPEP project we are investigating and characterizing these two reference systems with respect to production, operability, and safety performance criteria. Under production, plant configuration and working fluids are being studied for their effect on efficiency. Under operability, control strategies are being developed with the goal of maintaining equipment within operating limits while meeting changes in demand. Safety studies are to investigate plant response for equipment failures. Specific objectives in FY07 were (1) to develop HyPEP Beta and verification and validation (V&V) plan, (2) to perform steady state system integration, (3) to perform parametric studies with various working fluids and power conversion unit (PCU) configurations, (4) the study of design options such as pressure, temperature, etc. (5) to develop a control strategy and (6) to perform transient analyses for plant upsets, control strategy, etc for hydrogen plant with PCU. This report describes the progress made in FY07 in each of the above areas. (1) The HyPEP code numeric scheme and Graphic User Interface have been tested and refined since the release of the alpha version a year ago. (2) The optimal size and design condition for the intermediate heat exchanger, one of the most important components for integration of the VHTR and HTSE plants, was estimated. (3) Efficiency calculations were performed for a variety of working fluids for

  3. The Effects of Rainfall on the Population Dynamics of an Endangered Aquatic Plant, Schoenoplectus gemmifer (Cyperaceae).

    PubMed

    Kitamura, Koshi; Kakishima, Satoshi; Uehara, Takashi; Morita, Satoru; Tainaka, Kei-Ichi; Yoshimura, Jin

    2016-01-01

    The conservation of aquatic plants in river ecosystems should consider the wash-out (away) problem resulting from severe rainfall. The aquatic plant Schoenoplectus gemmifer is an endangered species endemic to Japan. Our previous study reported that the population size of S. gemmifer in Hamamatsu city, Japan, had decreased by one-tenth because many individuals had been washed out by a series of heavy rains in 2004. However, there is insufficient information on the ecological nature of this endangered aquatic plant for adequate conservation. In this paper, we report the population dynamics of one population in Hamamatsu city from 2004 to 2012 in relation to rainfall. We surveyed the number and growing location of all living individuals in the population 300 times during the study period. To examine the temporal changes of individual plants, we also counted the number of culms for 38 individuals in four observations among 300 records. Decreases and increases in the population size of this plant were associated with washing out and the settlement of gemmae (vegetative propagation), respectively. The major cause of the reduction in the population size was an increase in the number of washed-out individuals and not the decreased settlement of gemmae. The wash-out rates for small and large individuals were not significantly different. Small individuals having a stream form with linear leaves resisted flooding, and large individuals were often partially torn off by flooding events. Modification of river basins to reduce the flow velocity may be effective for the conservation of S. gemmifer.

  4. How does altered precipitation and annual grass invasion affect plant N uptake in a native semi-arid shrub community?

    NASA Astrophysics Data System (ADS)

    Mauritz, M.; Lipson, D.; Cleland, E. E.

    2012-12-01

    Climate change is expected to alter precipitation patterns, which will change the timing and amount of plant resources. Precipitation patterns determine water and nitrogen (N) availability, because water stimulates microbial N turnover and N transport. In order for plants to utilize water and N, they must coincide with the phenology and meet physiological requirements of the plant. As resource supply shifts, differences in species' ability to acquire resources will affect plant community composition. Semiarid ecosystems, such as shrublands in Southern California, are particularly sensitive to shifts in precipitation because they are severely water limited. This study takes advantage of the altered phenology and resource demands presented by invasive annual grasses in a native semiarid shrubland. The goal is to understand how altered precipitation patterns affect plant N uptake. Rainfall levels were manipulated to 50% and 150% of ambient levels. It is expected that higher rainfall levels promote annual grass invasion because grasses have higher water and N requirements and begin to grow earlier in the season than shrubs. A 15N tracer was added with the first rain event and plant samples were collected regularly to track the movement of N into the plants. Net soil N accumulation was determined using resin bags. Invasive grasses altered the timing and amount of N uptake but amount of rainfall had less effect on N distribution. 15N was detected sooner and at higher level in grasses than shrubs. 24hours after the first rain event 15N was detectable in grasses, 15N accumulated rapidly and peaked 2 months earlier than shrubs. Shrub 15N levels remained at pre-rain event levels for the first 2 months and began to increase at the beginning of spring, peak mid-spring and decline as the shrubs entered summer dormancy. One year later 15N levels in annual grass litter remained high, while 15N levels in shrubs returned to initial background levels as a result of resorption. 15N

  5. Molecular dissection of the cellular mechanisms involved in nickel hyperaccumulation in plants. 1998 annual progress report

    SciTech Connect

    Salt, D.

    1998-06-01

    'Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1--2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determine metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. The long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, the strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information the authors propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumulation in Thlaspi goesingense, a Ni hyperaccumulator species.'

  6. Managing breaches of containment and eradication of invasive plant populations

    PubMed Central

    Fletcher, Cameron S; Westcott, David A; Murphy, Helen T; Grice, Anthony C; Clarkson, John R

    2015-01-01

    Containment can be a viable strategy for managing invasive plants, but it is not always cheaper than eradication. In many cases, converting a failed eradication programme to a containment programme is not economically justified. Despite this, many contemporary invasive plant management strategies invoke containment as a fallback for failed eradication, often without detailing how containment would be implemented. We demonstrate a generalized analysis of the costs of eradication and containment, applicable to any plant invasion for which infestation size, dispersal distance, seed bank lifetime and the economic discount rate are specified. We estimate the costs of adapting eradication and containment in response to six types of breach and calculate under what conditions containment may provide a valid fallback to a breached eradication programme. We provide simple, general formulae and plots that can be applied to any invasion and show that containment will be cheaper than eradication only when the size of the occupied zone exceeds a multiple of the dispersal distance determined by seed bank longevity and the discount rate. Containment becomes proportionally cheaper than eradication for invaders with smaller dispersal distances, longer lived seed banks, or for larger discount rates. Both containment and eradication programmes are at risk of breach. Containment is less exposed to risk from reproduction in the ‘occupied zone’ and three types of breach that lead to a larger ‘occupied zone’, but more exposed to one type of breach that leads to a larger ‘buffer zone’. For a well-specified eradication programme, only the three types of breach leading to reproduction in or just outside the buffer zone can justify falling back to containment, and only if the expected costs of eradication and containment were comparable before the breach. Synthesis and applications. Weed management plans must apply a consistent definition of containment and provide sufficient

  7. Managing breaches of containment and eradication of invasive plant populations.

    PubMed

    Fletcher, Cameron S; Westcott, David A; Murphy, Helen T; Grice, Anthony C; Clarkson, John R

    2015-02-01

    Containment can be a viable strategy for managing invasive plants, but it is not always cheaper than eradication. In many cases, converting a failed eradication programme to a containment programme is not economically justified. Despite this, many contemporary invasive plant management strategies invoke containment as a fallback for failed eradication, often without detailing how containment would be implemented.We demonstrate a generalized analysis of the costs of eradication and containment, applicable to any plant invasion for which infestation size, dispersal distance, seed bank lifetime and the economic discount rate are specified. We estimate the costs of adapting eradication and containment in response to six types of breach and calculate under what conditions containment may provide a valid fallback to a breached eradication programme.We provide simple, general formulae and plots that can be applied to any invasion and show that containment will be cheaper than eradication only when the size of the occupied zone exceeds a multiple of the dispersal distance determined by seed bank longevity and the discount rate. Containment becomes proportionally cheaper than eradication for invaders with smaller dispersal distances, longer lived seed banks, or for larger discount rates.Both containment and eradication programmes are at risk of breach. Containment is less exposed to risk from reproduction in the 'occupied zone' and three types of breach that lead to a larger 'occupied zone', but more exposed to one type of breach that leads to a larger 'buffer zone'.For a well-specified eradication programme, only the three types of breach leading to reproduction in or just outside the buffer zone can justify falling back to containment, and only if the expected costs of eradication and containment were comparable before the breach.Synthesis and applications. Weed management plans must apply a consistent definition of containment and provide sufficient implementation detail

  8. H-coal pilot plant. Phase II. Construction. Phase III. Operation. Annual report No. 3

    SciTech Connect

    Not Available

    1981-02-04

    At the request of DOE Oak Ridge, ASFI agreed to assume responsibility for completion of Plant construction in December, 1979, at which time Badger Plants' on-site work was ended. This construction effort consisted of electric heat tracing and insulation of piping and instrumentation. At the close of the reporting period the work was completed, or was projected to be completed, within the ASFI budgeted amounts and by dates that will not impact Plant operations. Engineering design solutions were completed for problems encountered with such equipment as the High Pressure Letdown Valves; Slurry Block Valves; Slurry Pumps; the Bowl Mill System; the Dowtherm System; and the Ebullating Pump. A Corrosion Monitoring Program was established. With the exception of Area 500, the Antisolvent Deashing Unit, all operating units were commissioned and operated during the reporting period. Coal was first introduced into the Plant on May 29, 1980, with coal operations continuing periodically through September 30, 1980. The longest continuous coal run was 119 hours. A total of 677 tons of Kentucky No. 11 Coal were processed during the reporting period. The problems encountered were mechanical, not process, in nature. Various Environmental and Health programs were implemented to assure worker safety and protection and to obtain data from Plant operations for scientific analysis. These comprehensive programs will contribute greatly in determining the acceptability of long term H-Coal Plant operations.

  9. Annual radiological environmental monitoring report: Watts Bar Nuclear Plant, 1992. Operations Services/Technical Programs

    SciTech Connect

    Not Available

    1993-04-01

    This report describes the preoperational environmental radiological monitoring program conducted by TVA in the vicinity of the Watts Bar Nuclear Plant (WBN) in 1992. The program includes the collection of samples from the environment and the determination of the concentrations of radioactive materials in the samples. Samples are taken from stations in the general area of the plant and from areas that will not be influenced by plant operations. Material sampled includes air, water, milk, foods, vegetation, soil, fish, sediment, and direct radiation levels. During plant operations, results from stations near the plant will be compared with concentrations from control stations and with preoperational measurements to determine potential impacts to the public. Exposures calculated from environmental samples were contributed by naturally occurring radioactive materials, from materials commonly found in the environment as a result of atmospheric fallout, or from the operation of other nuclear facilities in the area. Since WBN has not operated, there has been no contribution of radioactivity from the plant to the environment.

  10. Response of Some Common Annual Bedding Plants to Three Species of Meloidogyne

    PubMed Central

    McSorley, R.; Frederick, J. J.

    1994-01-01

    Twelve ornamental bedding plant cultivars were grown in soil infested with isolates of Meloidogyne incognita race 1, M. javanica, or M. arenaria race 1 in a series of tests in containers in a growth room. Root galling (0-5 scale) and eggs/plant were evaluated 8-10 weeks after soil infestation and seedling transplantation. Snapdragon, Antirrhinum majus cv. First Ladies, was extensively galled and highly susceptible (mean gall rating ≥4.2 and ≥14,500 eggs/plant), and Celosia argentea cv. Century Mix and Coleus blumei cv. Rainbow were susceptible (>1,500 eggs/plant) to all three Meloidogyne isolates. Response of Petunia x hybrida varied with cultivar and nematode isolate. Little or no galling or egg production from any Meloidogyne isolate was observed on Ageratum houstonianum cv. Blue Mink, Lobularia maritima cv. Rosie O'Day, or Tagetes patula cv. Dwarf Primrose. Galling was slight (mean rating ≤2.0) but varied with nematode species on Dianthus chinensis cv. Baby Doll Mix, Salvia splendens cv. Bonfire, and Vinca rosea cv. Little Bright Eye. Verbena × hybrida cv. Florist was heavily infected (gall rating >4.0 and ≥7,900 eggs/plant) by M. javanica and M. arenaria but was nearly free of galling from M. incognita. Zinna elegans cv. Scarlet was nearly free of galling from M. incognita and M. arenaria but was susceptible (mean gall rating = 2.9; 3,400 eggs/plant) to M. javanica. PMID:19279963

  11. Response of some common annual bedding plants to three species of meloidogyne.

    PubMed

    McSorley, R; Frederick, J J

    1994-12-01

    Twelve ornamental bedding plant cultivars were grown in soil infested with isolates of Meloidogyne incognita race 1, M. javanica, or M. arenaria race 1 in a series of tests in containers in a growth room. Root galling (0-5 scale) and eggs/plant were evaluated 8-10 weeks after soil infestation and seedling transplantation. Snapdragon, Antirrhinum majus cv. First Ladies, was extensively galled and highly susceptible (mean gall rating >/=4.2 and >/=14,500 eggs/plant), and Celosia argentea cv. Century Mix and Coleus blumei cv. Rainbow were susceptible (>1,500 eggs/plant) to all three Meloidogyne isolates. Response of Petunia x hybrida varied with cultivar and nematode isolate. Little or no galling or egg production from any Meloidogyne isolate was observed on Ageratum houstonianum cv. Blue Mink, Lobularia maritima cv. Rosie O'Day, or Tagetes patula cv. Dwarf Primrose. Galling was slight (mean rating 4.0 and >/=7,900 eggs/plant) by M. javanica and M. arenaria but was nearly free of galling from M. incognita. Zinna elegans cv. Scarlet was nearly free of galling from M. incognita and M. arenaria but was susceptible (mean gall rating = 2.9; 3,400 eggs/plant) to M. javanica.

  12. Risk of exotic annual grass-fire cycle in Goose Creek milkvetch habitat

    USDA-ARS?s Scientific Manuscript database

    There is a concern that habitats surrounding Goose Creek milkvetch populations are at risk of exotic annual grass invasion leading to an exotic annual grass-fire cycle. We sampled plant community and site characteristics to evaluate the risk of these habitats developing an exotic annual grass-fire ...

  13. Influence of Habitat Modifications on Habitat Composition and Anadromous Salmonid Populations in Fish Creek, Oregon, 1983-1988 Annual Report.

    SciTech Connect

    Reeves, Gordon H.; Everest, Fred H.; Hohler, David B.

    1990-05-01

    Modification of degraded habitats to increase populations of anadromous salmonids is a major focus of management agencies throughout the Pacific Northwest. Millions of dollars are spent annually on such efforts. Inherent in implementing habitat improvements is the need for quantitative evaluation of the biological and physical effects of such work. Reeves et al. (in press), however, noted that such evaluations are rare, making it difficult to assess the true results of habitat work. While it is not economically possible to thoroughly evaluate every habitat project, it is essential that intensive evaluations be done on selected representative projects. One such evaluation program has been underway since 1982 on Fish Creek, a tributary of the Clackamas River near Estacada, OR. Habitat modification has been done by the USDA Forest Service, Estacada Ranger District, Mt. Hood National Forest with funding provided in part by the Bonneville Power Administration (BPA). The USDA Forest Service, Anadromous Fish Habitat Research Unit, Pacific Northwest Research Station (PNW), Corvallis, OR is charged with: (1) evaluating the biological and physical responses to habitat modifications on a basin scale; and (2) developing a cost-benefit analysis of the program. Preliminary results have been reported in a series of annual publications, Everest and Sedell 1983, 1984 and Everest et al. 1985, 1986, 1987, 1988. The objectives of this paper are to: (1) report 1988 observations of biological and physical changes in habitat, salmonid populations, and smolt production in Fish Creek, and (2) examine preliminary trends in fish habitat and populations related to habitat improvement over the period 1983-1988. We have prefaced the trends in the latter objective as preliminary because we believe it could take a minimum of 10 years before the full biological and physical responses to habitat work are realized. We therefore urge caution in interpreting these preliminary results.

  14. Evaluate Habitat Use and Population Dynamics of Lampreys in Cedar Creek, 2000 Annual Report.

    SciTech Connect

    Stone, Jennifer

    2001-03-31

    Pacific lamprey (Lampetra tridentata) in the Columbia River Basin have declined to a remnant of their pre-1940s populations and the status of the western brook lamprey (L. richardsoni) is unknown. Identifying the biological and ecological factors limiting lamprey populations is critical to their recovery, but little research has been conducted on these species within the Columbia River Basin. This ongoing, multi-year study examines lamprey populations in Cedar Creek, Washington, a third-order tributary to the Lewis River. Adult (n = 40), metamorphosed (n = 116), transforming (n = 10), and ammocoete (n = 870) stages from both species were examined in 2000. Lamprey were captured using adult fish ladders, rotary screw traps, and lamprey electrofishers, and spawning ground surveys were conducted. US Forest Service level II and strategic point-specific habitat surveys were conducted to assess habitat requirements of both adult and larval lamprey. Multivariate statistics will be applied to determine relationships between abundance and habitat.

  15. Plasticity and evolution in drought avoidance and escape in the annual plant Brassica rapa.

    PubMed

    Franks, Steven J

    2011-04-01

    A key question in ecological genetics is to what extent do plants adapt to changes in climatic conditions, such as drought, through plasticity or evolution. To address this question, seeds of 140 maternal families of Brassica rapa were generated from collections made before (1997) and after (2004) a natural drought. These seeds were planted in the glasshouse and grown under low-water and high-water conditions. Post-drought lines flowered earlier than pre-drought lines, showing an evolutionary shift to earlier flowering. There was significant genetic variation and genotype by environment (G × E) interactions in flowering time, indicating genetic variation in plasticity in this trait. Plants that flowered earlier had fewer leaf nodes and lower instantaneous (A/g) and integrated (δ(13)C) water use efficiency than late-flowering plants. These results suggest that B. rapa plants escape drought through early flowering rather than avoid drought through increased water use efficiency. The mechanism of this response appears to be high transpiration and inefficient water use, leading to rapid development. These findings demonstrate a trade-off between drought avoidance and escape, and indicate that, in this system, where drought acts to shorten the growing season, selection for drought escape through earlier flowering is more important than phenotypic plasticity. © 2011 The Author. New Phytologist © 2011 New Phytologist Trust.

  16. Habitat patch shape, not corridors, determines herbivory and fruit production of an annual plant.

    PubMed

    Evans, Daniel M; Turley, Nash E; Levey, Douglas J; Tewksbury, Joshua J

    2012-05-01

    Habitat corridors confer many conservation benefits by increasing movement of organisms between habitat patches, but the benefits for some species may exact costs for others. For example, corridors may increase the abundance of consumers in a habitat to the detriment of the species they consume. In this study we assessed the impact of corridors on insect herbivory of a native plant, Solanum americanum, in large-scale, experimentally fragmented landscapes. We quantified leaf herbivory and assessed fruit production as a proxy for plant fitness. We also conducted field surveys of grasshoppers (Orthoptera), a group of abundant, generalist herbivores that feed on S. americanum, and we used exclosure cages to explicitly link grasshopper herbivory to fruit production of individual S. americanum. The presence of corridors did not increase herbivory or decrease plant fruit production. Likewise, corridors did not increase grasshopper abundance. Instead, patches in our landscapes with the least amount of edge habitat and the greatest amount of warmer "core" area had the highest levels of herbivory, the largest cost to plant fruit production as a result of herbivory, and the most grasshoppers. Thus habitat quality, governed by patch shape, can be more important than connectivity for determining levels of herbivory and the impact of herbivory on plant fitness in fragmented landscapes.

  17. The influence of annual species composition and density on perennial seedling density in four plant communities in the Northern Mojave Desert

    SciTech Connect

    Hall, P.F.; Angerer, J.P.; Ostler, W.K.; Schultz, B.W.

    1993-12-31

    According to the Nuclear Waste Policy Act of 1982 (as amended in 1987), the US Department of Energy (DOE) must study and characterize Yucca Mountain as a potential site for long-term underground storage of high-level nuclear waste. Part of the overall site characterization program is to monitor potential impacts on the biological resources at Yucca Mountain. A part of the biological monitoring program, assessed vegetation parameters included density of annual and perennial seedlings. This data was used to evaluate: (1) seed germination and seed survival; and (2) if annual plant species density and cover influence perennial seedling survival. Twelve permanent 200 {times} 200-m ,study plots were established in each of four vegetation associations present in the Yucca Mountain Project area. During the spring of 1992, 20 to 60, 1-m{sup 2} randomly-located quadrats per study plot were measured for perennial seedling density, annual species density, and annual species composition. Perennial seedlings found in 1992 were relocated in the spring of 1993, and survival determined. Cover was measure in the spring of 1992. Annual plant density and cover was greatest in the Larrea-Lycium-Grayia vegetation association, and lowest in the Larrea-Ambrosia vegetation association. Annual seedling density had a negative exponential relationship with perennial seedling density in 1992. However, non-linear regression analysis indicated that 1992 annual seedling density had a greater impact on survival of pernnial seedlings from 1992 to 1993.

  18. Transcriptional variation associated with cactus host plant adaptation in Drosophila mettleri populations.

    PubMed

    Hoang, Kim; Matzkin, Luciano M; Bono, Jeremy M

    2015-10-01

    Although the importance of host plant chemistry in plant-insect interactions is widely accepted, the genetic basis of adaptation to host plants is not well understood. Here, we investigate transcriptional changes associated with a host plant shift in Drosophila mettleri. While D. mettleri is distributed mainly throughout the Sonoran Desert where it specializes on columnar cacti (Carnegiea gigantea and Pachycereus pringleii), a population on Santa Catalina Island has shifted to chemically divergent coastal prickly pear cactus (Opuntia littoralis). We compared gene expression of larvae from the Sonoran Desert and Santa Catalina Island when reared on saguaro (C. gigantea), coastal prickly pear and laboratory food. Consistent with expectations based on the complexity and toxicity of cactus relative to laboratory food, within-population comparisons between larvae reared on these food sources revealed transcriptional differences in detoxification and other metabolic pathways. The majority of transcriptional differences between populations on the cactus hosts were independent of the rearing environment and included a disproportionate number of genes involved in processes relevant to host plant adaptation (e.g. detoxification, central metabolism and chemosensory pathways). Comparisons of transcriptional reaction norms between the two populations revealed extensive shared plasticity that likely allowed colonization of coastal prickly pear on Santa Catalina Island. We also found that while plasticity may have facilitated subsequent adaptive divergence in gene expression between populations, the majority of genes that differed in expression on the novel host were not transcriptionally plastic in the presumed ancestral state. © 2015 John Wiley & Sons Ltd.

  19. Untargeted Metabotyping Lolium perenne Reveals Population-Level Variation in Plant Flavonoids and Alkaloids

    PubMed Central

    Cao, Mingshu; Fraser, Karl; Jones, Chris; Stewart, Alan; Lyons, Thomas; Faville, Marty; Barrett, Brent

    2017-01-01

    Metabolomics provides a powerful platform to characterize plants at the biochemical level, allowing a search for underlying genes and associations with higher level complex traits such as yield and nutritional value. Efficient and reliable methods to characterize metabolic variation in economically important species are considered of high value to the evaluation and prioritization of germplasm and breeding lines. In this investigation, a large-scale metabolomic survey was performed on a collection of diverse perennial ryegrass (Lolium perenne L.) plants. A total of 2,708 data files, derived from liquid chromatography coupled to high resolution mass spectrometry (LCMS), were selected to assess the effectiveness and efficiency of applying high throughput metabolomics to survey chemical diversity in plant populations. The data set was generated from 23 ryegrass populations, with 3–25 genotypes per population, and five clonal replicates per genotype. We demonstrate an integrated approach to rapidly mine and analyze metabolic variation from this large, multi-batch LCMS data set. After performing quality control, statistical data mining and peak annotation, a wide range of variation for flavonoid glycosides and plant alkaloids was discovered among the populations. Structural variation of flavonoids occurs both in aglycone structures and acetylated/malonylated/feruloylated sugar moieties. The discovery of comprehensive metabolic variation among the plant populations offers opportunities to probe into the genetic basis of the variation, and provides a valuable resource to gain insight into biochemical functions and to relate metabolic variation with higher level traits in the species. PMID:28223996

  20. Plant population growth and competition in a light gradient: a mathematical model of canopy partitioning.

    PubMed

    Vance, Richard R; Nevai, Andrew L

    2007-03-21

    Can a difference in the heights at which plants place their leaves, a pattern we call canopy partitioning, make it possible for two competing plant species to coexist? To find out, we examine a model of clonal plants living in a nonseasonal environment that relates the dynamical behavior and competitive abilities of plant populations to the structural and functional features of the plants that form them. This examination emphasizes whole plant performance in the vertical light gradient caused by self-shading. This first of three related papers formulates a prototype single species Canopy Structure Model from biological first principles and shows how all plant properties work together to determine population persistence and equilibrium abundance. Population persistence is favored, and equilibrium abundance is increased, by high irradiance, high maximum photosynthesis rate, rapid saturation of the photosynthetic response to increased irradiance, low tissue respiration rate, small amounts of stem and root tissue necessary to support the needs of leaves, and low density of leaf, stem, and root tissues. In particular, equilibrium abundance decreases as mean leaf height increases because of the increased cost of manufacturing and maintaining stem tissue. All conclusions arise from this formulation by straightforward analysis. The argument concludes by stating this formulation's straightforward extension, called a Canopy Partitioning Model, to two competing species.

  1. Estimation of potential population level effects of contaminants on wildlife. 1998 annual progress report

    SciTech Connect

    Sample, B.E.; Suter, G.W. II; Rose, K.A.

    1998-06-01

    'The objective of this project is to provide DOE with improved methods to assess risks from contaminants to wildlife populations. The current approach for wildlife risk assessment consists of comparison of contaminant exposure estimates for individual animals to literature-derived toxicity test endpoints. These test endpoints are assumed to estimate thresholds for population-level effects. For several reasons, uncertainties associated with this approach are considerable. First, because toxicity data are not available for most potential wildlife endpoint species, extrapolation of toxicity data from test species to the species of interest is required. There is no consensus on the most appropriate extrapolation method. Second, toxicity data are represented as statistical measures (e.g., NOAELs or LOAELs) that provide no information on the nature or magnitude of effects. The level of effect is an artifact of the replication and dosing regime employed, and does not indicate how effects might increase with increasing exposure. Consequently, slight exceedance of a LOAEL is not distinguished from greatly exceeding it. Third, the relationship of toxic effects on individuals to effects on populations is poorly estimated by existing methods. It is assumed that if the exposure of individuals exceeds levels associated with impaired reproduction, then population level effects are likely. Uncertainty associated with this assumption is large because depending on the reproductive strategy of a given species, comparable levels of reproductive impairment may result in dramatically different population-level responses. The authors are working on several tasks to address these problems: (1) investigation of the validity of the current allometric scaling approach for interspecies extrapolation and development of new scaling models; (2) development of dose-response models for toxicity data presented in the literature; and (3) development of matrix-based population models that, coupled

  2. Genotypic and phenotypic diversity in populations of plant-probiotic Pseudomonas spp. colonizing roots.

    PubMed

    Picard, Christine; Bosco, Marco

    2008-01-01

    Several soil microorganisms colonizing roots are known to naturally promote the health of plants by controlling a range of plant pathogens, including bacteria, fungi, and nematodes. The use of theses antagonistic microorganisms, recently named plant-probiotics, to control plant-pathogenic fungi is receiving increasing attention, as they may represent a sustainable alternative to chemical pesticides. Many years of research on plant-probiotic microorganisms (PPM) have indicated that fluorescent pseudomonads producing antimicrobial compounds are largely involved in the suppression of the most widespread soilborne pathogens. Phenotype and genotype analysis of plant-probiotic fluorescent pseudomonads (PFP) have shown considerable genetic variation among these types of strains. Such variability plays an important role in the rhizosphere competence and the biocontrol ability of PFP strains. Understanding the mechanisms by which genotypic and phenotypic diversity occurs in natural populations of PFP could be exploited to choose those agricultural practices which best exploit the indigenous PFP populations, or to isolate new plant-probiotic strains for using them as inoculants. A number of different methods have been used to study diversity within PFP populations. Because different resolutions of the existing microbial diversity can be revealed depending on the approach used, this review first describes the most important methods used for the assessment of fluorescent Pseudomonas diversity. Then, we focus on recent data relating how differences in genotypic and phenotypic diversity within PFP communities can be attributed to geographic location, climate, soil type, soil management regime, and interactions with other soil microorganisms and host plants. It becomes evident that plant-related parameters exert the strongest influence on the genotypic and phenotypic variations in PFP populations.

  3. Genotypic and phenotypic diversity in populations of plant-probiotic Pseudomonas spp. colonizing roots

    NASA Astrophysics Data System (ADS)

    Picard, Christine; Bosco, Marco

    2008-01-01

    Several soil microorganisms colonizing roots are known to naturally promote the health of plants by controlling a range of plant pathogens, including bacteria, fungi, and nematodes. The use of theses antagonistic microorganisms, recently named plant-probiotics, to control plant-pathogenic fungi is receiving increasing attention, as they may represent a sustainable alternative to chemical pesticides. Many years of research on plant-probiotic microorganisms (PPM) have indicated that fluorescent pseudomonads producing antimicrobial compounds are largely involved in the suppression of the most widespread soilborne pathogens. Phenotype and genotype analysis of plant-probiotic fluorescent pseudomonads (PFP) have shown considerable genetic variation among these types of strains. Such variability plays an important role in the rhizosphere competence and the biocontrol ability of PFP strains. Understanding the mechanisms by which genotypic and phenotypic diversity occurs in natural populations of PFP could be exploited to choose those agricultural practices which best exploit the indigenous PFP populations, or to isolate new plant-probiotic strains for using them as inoculants. A number of different methods have been used to study diversity within PFP populations. Because different resolutions of the existing microbial diversity can be revealed depending on the approach used, this review first describes the most important methods used for the assessment of fluorescent Pseudomonas diversity. Then, we focus on recent data relating how differences in genotypic and phenotypic diversity within PFP communities can be attributed to geographic location, climate, soil type, soil management regime, and interactions with other soil microorganisms and host plants. It becomes evident that plant-related parameters exert the strongest influence on the genotypic and phenotypic variations in PFP populations.

  4. Population status of the American alligator on the Savannah River Plant, South Carolina

    SciTech Connect

    Murphy, T.M.

    1981-04-01

    Estimates are presented of alligator numbers, size distribution, sex ratios, reproductive effort, and population trends for all major components of the entire Savannah River Plant (SRP) alligator population. Savannah River Plant operations have impacted the alligator population in many different ways. The formation of man-made reservoirs has dramatically increased the amount of aquatic habitat available to alligators and has therefore increased the carrying capacity of the SRP site for this species. The thermal alteration of aquatic habitats on the SRP has also impacted the resident alligator population. Temperature elevations of aquatic habitat to greater than 38/sup 0/C result in the loss of this habitat to alligators. Moderate thermal increases on the other hand are responded to by alligator movement. The current information available on the alligators of the SRP suggests the following future trends: low density populations distant from thermally altered areas will continue at a low density with the exception of localized increases.

  5. Plant rhizosphere effects on metal mobilization and transport. 1998 annual progress report

    SciTech Connect

    Fan, T.W.M.

    1998-06-01

    'Information on the mechanism of how plants mobilize, uptake, and metabolize metal ions is very limited. Especially deficient is the understanding of these processes involving pollutant metal ions and interactions among these ions. Based on the current knowledge regarding nutrient ions, it is clear that elucidation of rhizospheric processes such as exudation of organic ligands by plant roots and plant metabolism/adaptation involving these biogenic chelators is critically important. A mechanistic insight into these processes will advance knowledge in microbe-plant host interactions and how metal ions are mobilized, immobilized, and sequestered by these interactions. This, in turn, is essential to applications such as phytobioremediation and microbioremediation of metal ion pollution. Root exudation also serves many other important rhizosphere functions including energy supply for microbial degradation of organic pollutants, structuring of microbial community, and the formation of soil humic materials which are considered to be a major sink for both organic and inorganic pollutants. How root exudates function is critically dependent on the chemical nature of exudate components. Therefore, a comprehensive characterization of all major exudate components, regardless of their chemical class, should facilitate the development and implementation of bioremediation for both organic and inorganic pollutants. Therefore, the objectives of this project are: (1) To obtain a comprehensive composition of major organic components in plant root exudates as a function of different metal ions; (2) To examine plant metabolic response(s) to these metal ion treatments, with emphasis on biosynthetic pathways of organic ligands; and (3) To investigate the effect(s) of soil microbial (e.g. mycorrhizae) association on (1) and (2).'

  6. Cost and quality of fuels for electric utility plants: Energy data report. 1980 annual

    SciTech Connect

    Not Available

    1981-06-25

    In 1980 US electric utilities reported purchasng 594 million tons of coal, 408.5 million barrels of oil and 3568.7 billion ft/sup 3/ of gas. As compared with 1979 purchases, coal rose 6.7%, oil decreased 20.9%, and gas increased for the fourth year in a row. This volume presents tabulated and graphic data on the cost and quality of fossil fuel receipts to US electric utilities plants with a combined capacity of 25 MW or greater. Information is included on fuel origin and destination, fuel types, and sulfur content, plant types, capacity, and flue gas desulfurization method used, and fuel costs. (LCL)

  7. Comprehensive cooling water study annual report. Volume II: introduction and site description, Savannah River Plant

    SciTech Connect

    Gladden, J.B.; Lower, M.W.; Mackey, H.E.; Specht, W.L.; Wilde, E.W.

    1985-07-01

    The Comprehensive Cooling Water Study was initiated in 1983 to evaluate the environmental effecs of the intake and release of cooling water on the structure and function of aquatic ecosystems at the Savannah River Plant. This report presents the results from the first year of the two year study and also summarizes results from previous studies on aquatic ecosystems of the Savannah River Plant. Five major program elements are addressed: water quality, radionuclide and heavy metal transport, wetlands ecology, aquatic ecology, and endangered species. 63 refs., 13 figs., 7 tabs.

  8. Monitoring trends in bird populations: addressing background levels of annual variability in counts

    Treesearch

    Jared Verner; Kathryn L. Purcell; Jennifer G. Turner

    1996-01-01

    Point counting has been widely accepted as a method for monitoring trends in bird populations. Using a rigorously standardized protocol at 210 counting stations at the San Joaquin Experimental Range, Madera Co., California, we have been studying sources of variability in point counts of birds. Vegetation types in the study area have not changed during the 11 years of...

  9. Starting new populations of longleaf pine ground-layer plants in the outer Coastal Plain of South Carolina, USA.

    Treesearch

    Jeff S. Glitzenstein; Donna R. Streng; Dale D. Wade; John Brubaker

    2001-01-01

    Southeastern United States habitats dominated by longleaf pine (Pinus palustris Miller) and associated plant species have declined dangerously. Conservation of rare and common plants of longleaf pine habitats may be aided by starting new populations in the field. We review methods for initiating plant populations and integrate information from our...

  10. Population abundance of Frankliniella occidentalis (Thysanoptera: Thripidae) and natural enemies on plant hosts in central Chile.

    PubMed

    Ripa, Renato; Funderburk, Joe; Rodriguez, Fernando; Espinoza, Fernanda; Mound, Laurence

    2009-04-01

    Populations of the invasive Frankliniella occidentalis (Pergande) are serious pests of agricultural crops in the Aconcagua Valley of central Chile. An extensive survey was conducted of 55 plant species in 24 families to identify plant hosts of F. occidentalis and to determine its relative abundance on each host during each season. A more intensive study was conducted on selected plant species serving as reproductive hosts to determine the population dynamics of F. occidentalis and to evaluate the potential importance of Orius species and other natural enemies for controlling F. occidentalis. Adults of F. occidentalis were active during each season of the year inhabiting the flowers of 91% of the sampled plant species in 22 families, and 86% of these plant species in 19 families served as reproductive hosts. The number of host plant species used was greatest in the spring and least in the winter. All of the hosts except Medicago sativa L. were used only when flowering. Populations of F. occidentalis were significantly aggregated in M. sativa in the terminal buds over the leaves when the host was not flowering, and in the flowers, followed by the terminal buds, followed by the leaves when the host was flowering. Larvae were 1.3-2.3 times more abundant on dates when M. sativa was flowering. There were no identifiable patterns in plant hosts based on endemicity or plant family. Most of the plant species used by F. occidentalis were inferior quality hosts where populations either declined or were stable. Populations of F. occidentalis on low-quality hosts generally escaped predation by Orius species and competition by other species of thrips. Only 25% of the food hosts and 28% of the reproductive hosts for F. occidentalis in the extensive survey, respectively, were host plants for Orius. Parasitoids and other predators were not found to be important in suppressing thrips on any of the plant hosts. Populations of F. occidentalis increased on only a few hosts, including M

  11. Demographic stochasticity in small remnant populations of the declining distylous plant Primula veris

    USGS Publications Warehouse

    Kery, M.; Matthies, D.; Schmid, B.

    2003-01-01

    We studied ecological consequences of distyly for the declining perennial plant Primula veris in the Swiss Jura. Distyly favours cross-fertilization and avoids inbreeding, but may lead to pollen limitation and reduced reproduction if morph frequencies deviate from 50 %. Disassortative mating is promoted by the reciprocal position of stigmas and anthers in the two morphs (pin and thrum) and by intramorph incompatibility and should result in equal frequencies of morphs at equilibrium. However, deviations could arise because of demographic stochasticity, the lower intra-morph incompatibility of the pin morph, and niche differentiation between morphs. Demographic stochasticity should result in symmetric deviations from an even morph frequency among populations and in increased deviations with decreasing population size. If crosses between pins occurred, these would only generate pins, and this could result in a pin-bias of morph frequencies in general and in small populations in particular. If the morphs have different niches, morph frequencies should be related to environmental factors, morphs might be spatially segregated, and morphological differences between morphs would be expected. We tested these hypotheses in the declining distylous P. veris. We studied morph frequencies in relation to environmental conditions and population size, spatial segregation in field populations, morphological differences between morphs, and growth responses to nutrient addition. Morph frequencies in 76 populations with 1 - 80000 flowering plants fluctuated symmetrically about 50 %. Deviations from 50 % were much larger in small populations, and sixof the smallest populations had lost one morph altogether. In contrast, morph frequencies were neither related to population size nor to 17 measures of environmental conditions. We found no spatial segregation or morphological differences in the field or in the common garden. The results suggest that demographic stochasticity caused

  12. Impact of plant development on the rhizobacterial population of Arachis hypogaea: a multifactorial analysis.

    PubMed

    Haldar, Shyamalina; Sengupta, Sanghamitra

    2015-07-01

    Present study investigates the impact of plant development on the structure and composition of root-associated bacterial community of groundnut (Arachis hypogaea) plant, an economically important oilseed legume. Relative abundance of total and active bacteria were studied in bulk soil and rhizosphere samples collected from different growth stages of groundnut plant by sequencing PCR-amplified 16S rRNA gene fragments from soil genomic DNA and reverse-transcribed soil community RNA. Plant growth promoting potential of cultivable rhizobacteria was evaluated using assays for inorganic phosphate solubilization and production of indole acetic acid, siderophores, biofilm, 1-amino-cyclopropane-1-carboxylate deaminase, laccase, and anti-fungal chemicals. Our study demonstrates that groundnut plant rhizosphere harbors a core microbiome populated by Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Acidobacteria. A distinct bacterial assemblage at nodulation stage due to predominance of Flavobacteria and Actinobacteria in DNA and RNA derived libraries respectively was also observed. Majority of cultivable isolates exhibiting plant growth promoting activities belonged to Proteobacteria and Firmicutes. Of them, Pseudomonas indica and Bacillus megaterium were detected in the rhizosphere samples from all the developmental stages of groundnut plant. This polyphasic study establishes the impact of plant development on rhizobacterial population of groundnut and underscores the applicability of soil isolates as a reliable component in sustainable agriculture.

  13. Trade-off between plant growth and defense? A comparison of sagebrush populations.

    PubMed

    Messina, Frank J; Durham, Susan L; Richards, James H; McArthur, Durant E

    2002-03-01

    We used ecotypic variation in big sagebrush (Artemisia tridentata) to examine potential trade-offs between inherent growth rate and tolerance or resistance to herbivory. Seeds were obtained from seven geographic populations, and 1,120 seedlings were established in a common garden. In one set of plots, plants were subjected to five treatments: control, regular insecticide spray, moderate browsing, severe browsing, or moderate browsing plus insecticide. Plants in a second set of plots were all untreated, and were used to estimate ambient growth, flower production, and susceptibility to herbivorous insects. In the first growing season, population differences in relative growth rate produced approximately seven-fold variation in mean biomass. Two populations of basin big sagebrush (A. tridentata tridentata) and one population of mountain big sagebrush (A. tridentata vaseyana) grew fastest; those of Wyoming big sagebrush (A. tridentata wyomingensis) showed the slowest growth. Bi-weekly application of insecticide for two growing seasons had no effect on the growth of either browsed or unbrowsed plants. All populations showed compensatory growth (but not overcompensation) in response to browsing, but the degree of compensation was unrelated to inherent growth rate. Similarly, there was no consistent relationship between plant growth rate and flower production in the second growing season. Some insects colonized fast-growing populations more frequently than slow-growing ones, but patterns of insect colonization were species-specific. At the level of geographic populations and subspecies, we found little evidence of a built-in trade-off between inherent growth rate and the ability to tolerate or resist herbivory. Because population ranks for growth rate changed substantially between seasons, attempts to correlate growth and defense characters need to account for differences in the growth trajectories of perennial plants.

  14. Consequences of vegetative herbivory for maintenance of intermediate outcrossing in an annual plant.

    PubMed

    Steets, Janette A; Hamrick, James L; Ashman, Tia-Lynn

    2006-11-01

    Given the occurrence of mixed mating systems among plants, a general mechanism explaining the evolution and maintenance of this condition is needed. Although numerous theoretical models predict mixed mating to be evolutionarily stable, conditions favoring intermediate selfing are often stringent and have limited applicability. Here we investigated the role of vegetative herbivory, a ubiquitous biotic factor limiting plant reproduction, in the mating system expression of Impatiens capensis (Balsaminaceae), a species with an obligate mixed-mating system (individuals produce both selfing, cleistogamous, and facultatively outcrossing, chasmogamous flowers). Herbivory reduced proportional chasmogamous reproduction partially, but not entirely, through a reduction in plant size and the strength of this effect varied among replicates. Herbivory decreased geitonogamous selfing in chasmogamous flowers via several mechanisms including reduced chasmogamous flower display size and pollinator visitation rate and altered pollinator composition. Overall, herbivory caused a decrease in whole-plant outcrossing, indicating that the effects of herbivory on proportional chasmogamous reproduction, which favor selfing, outweigh the effects on chasmogamous outcrossing rate, which favor outcrossing. Not only do our findings unravel the mechanisms underlying herbivore-mediated changes in the mating system, but they also point to the role of natural enemies in contributing to the maintenance of a mixed mating system.

  15. Structure, function, and biosynthesis of plant cell walls: proceedings of the seventh annual symposium in botany

    SciTech Connect

    Dugger, W.M.; Bartnicki-Garcia, S.

    1984-01-01

    Papers in the following areas were included in these symposium proceedings: (1) cell wall chemistry and biosynthesis; (2) cell wall hydrolysis and associated physiology; (3) cellular events associated with cell wall biosynthesis; and (4) interactions of plant cell walls with pathogens and related responses. Papers have been individually abstracted for the data base. (ACR)

  16. Forage radish winter cover crop suppresses winter annual weeds in fall and before corn planting

    USDA-ARS?s Scientific Manuscript database

    Forage radish (Raphanus sativus L. var. longipinnatus) is a new winter cover crop in the Mid-Atlantic region. The objective of this project was to characterize the repeatability, amount, and duration of weed suppression during and after a fall-planted forage radish cover crop and to quantify the sub...

  17. Nuclear waste-form risk assessment for US Defense waste at Savannah River Plant. Annual report FY 1981

    SciTech Connect

    Cheung, H.; Edwards, L.L.; Harvey, T.F.; Jackson, D.D.; Revelli, M.A.

    1981-12-01

    Savannah River Plant has been supporting the Lawrence Livermore National Laboratory in its present effort to perform risk assessments of alternative waste forms for defense waste. This effort relates to choosing a suitable combination of solid form and geologic medium on the basis of risk of exposure to future generations; therefore, the focus is on post-closure considerations of deep geologic repositories. The waste forms being investigated include borosilicate glass, SYNROC, and others. Geologic media under consideration are bedded salt, basalt, and tuff. The results of our work during FY 1981 are presented in this, our second annual report. The two complementary tasks that comprise our program, analysis of waste-form dissolution and risk assessment, are described.

  18. Evaluation of annual efficiencies of high temperature central receiver concentrated solar power plants with thermal energy storage.

    SciTech Connect

    Ehrhart, Brian David; Gill, David Dennis

    2013-07-01

    The current study has examined four cases of a central receiver concentrated solar power plant with thermal energy storage using the DELSOL and SOLERGY computer codes. The current state-of-the-art base case was compared with a theoretical high temperature case which was based on the scaling of some input parameters and the estimation of other parameters based on performance targets from the Department of Energy SunShot Initiative. This comparison was done for both current and high temperature cases in two configurations: a surround field with an external cylindrical receiver and a north field with a single cavity receiver. There is a fairly dramatic difference between the design point and annual average performance, especially in the solar field and receiver subsystems, and also in energy losses due to the thermal energy storage being full to capacity. Additionally, there are relatively small differences (<2%) in annual average efficiencies between the Base and High Temperature cases, despite an increase in thermal to electric conversion efficiency of over 8%. This is due the increased thermal losses at higher temperature and operational losses due to subsystem start-up and shut-down. Thermal energy storage can mitigate some of these losses by utilizing larger thermal energy storage to ensure that the electric power production system does not need to stop and re-start as often, but solar energy is inherently transient. Economic and cost considerations were not considered here, but will have a significant impact on solar thermal electric power production strategy and sizing.

  19. Effect of Planting Site Preparation, Hydrated Lime, and DBCP (1, 2-dibromo-3-chloropropane) on Populations of Macroposthonia xenoplax and Peach Tree Short Life in Georgia.

    PubMed

    Wehunt, E J; Weaver, D J

    1982-10-01

    Annual postplanting applications of 40.7 kg/ha DBCP (1,2-dibromo-3-chloropropane) controlled Macroposthonia xenoplax (Raski, 1952) deGrisse and Loof, 1965 in peach tree short life sites, reduced bacterial canker incidence from 74% to 6%, and inreased the average life of the trees from 3.9 to 6.8 yr for a 7-yr test period. Hydrated lime at 5.5 kg per planting site reduced bacterial canker incidence from 81% 57 % and increased the tree longevity from 2.6 to 6.0 yr. Populations M. xenoplax were inversely correlated with tree longevity.

  20. Neutron dosimetry at commercial nuclear plants. Annual report of Subtask D: TEPC feasibility

    SciTech Connect

    Cummings, F.M.; Endres, G.W.R.; McDonald, J.C.; Brackenbush, L.W.

    1984-06-01

    This study was designed to observe the feasibility of the use by NRC licensees of the tissue equivalent proportional counter (TEPC) system as a neutron monitoring instrument. Laboratory tissue equivalent proportional counters were irradiated using /sup 252/Cf sources at NBS and PNL and were irradiated inside containment of four operating nuclear power plants (two boiling water reactors and two pressurized water reactors). On the average, neutron dose-equivalent rates determined using the TEPC were 1.05 times the calculated dose-equivalent rates for the bare and moderated /sup 252/Cf sources and 0.86 times the dose-equivalent rates determined using the multispheres inside containment of nuclear power plants. Further, neutron dose equivalent rates determined using portable remmeters were an average of 1.71 times the dose equivalent determined using the multispheres inside the containment of nuclear power plants. It was observed that while electronic noise from temperature and vibrational effects inside containment prohibited an adequate measure of absorbed dose from gammas, the measurement of neutron absorbed dose was unaffected by these environmental parameters. It is recommended that for use inside containment at nuclear power plants: (1) the laboratory scale TEPC is the superior technique for accurate determination of neutron dose equivalent, (2) for remmeters similar to the one evaluated in this study, neutron dose equivalent response should be corrected to account for dependence of response on neutron energy or the remmeters should be calibrated using a moderated neutron source, and (3) at present, the TEPC should not be used to measure absorbed dose from gammas. Upon the advent of a proven miniaturized TEPC, this instrument may prove to be a desirable replacement for current portable neutron monitoring devices for the determination of dose equivalent inside containment of commercial nuclear power plants.

  1. Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

    PubMed Central

    Xue, Kai; Yuan, Mengting M.; Xie, Jianping; Li, Dejun; Qin, Yujia; Wu, Liyou; Deng, Ye; He, Zhili; Van Nostrand, Joy D.; Luo, Yiqi; Tiedje, James M.

    2016-01-01

    ABSTRACT Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened. PMID:27677789

  2. Abiotic and biotic resistance to grass invasion in serpentine annual plant communities.

    PubMed

    Going, Barbara Marie; Hillerislambers, Janneke; Levine, Jonathan M

    2009-04-01

    Biological invasions severely impact native plant communities, causing dramatic shifts in species composition and the restriction of native species to spatially isolated refuges. Competition from resident species and the interaction between resource limitation and competition have been overlooked as mechanisms of community resistance in refugia habitats. We examined the importance of these factors in determining the resistance of California serpentine plant communities to invasion by three common European grasses, Avena barbata, Bromus diandrus, and Hordeum murinum. We added seeds of each of these grasses to plots subjected to six levels of resource addition (N, P, Ca, H2O, all resources together, and a no-addition control) and two levels of competition (with resident community present or removed). Resource limitation and competition had strong effects on the biomass and reproduction of the three invaders. The addition of all resources together combined with the removal of the resident community yielded individual plants that were fourfold to 20-fold larger and sixfold to 20-fold more fecund than plants from control plots. Competitor removal alone yielded invaders that were twofold to sevenfold larger and twofold to ninefold more fecund. N addition alone or in combination with other resources led to a twofold to ninefold increase in the biomass and fecundity of the invaders. No other resource alone significantly affected native or invader performance, suggesting that N was the key limiting resource during our experiment. We found a significant interaction between abiotic and biotic resistance for Bromus, which experienced increased competitive suppression in fertilized plots. The threefold increase in resident biomass with N addition was likely responsible for this result. Our results confirm that serpentine plant communities are severely N limited, which, in combination with competition from resident species, promotes the resistance of these systems to invasions

  3. Population dynamics of bacteria involved in enhanced biological phosphorus removal in Danish wastewater treatment plants.

    PubMed

    Mielczarek, Artur Tomasz; Nguyen, Hien Thi Thu; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2013-03-15

    The enhanced biological phosphorus removal (EBPR) process is increasingly popular as a sustainable method for removal of phosphorus (P) from wastewater. This study consisted of a comprehensive three-year investigation of the identity and population dynamics of polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating organisms (GAOs) in 28 Danish municipal wastewater treatment plants with nutrient removal. Fluorescence in situ hybridization was applied to quantify ten probe-defined populations of PAO and GAO that in total constituted a large fraction (30% on average) of the entire microbial community targeted by the EUBmix probes. Two PAO genera, Accumulibacter and Tetrasphaera, were very abundant in all EBPR plants (average of 3.7% and 27% of all bacteria, respectively), and their abundance was relatively stable in the Danish full-scale plants without clear temporal variations. GAOs were occasionally present in some plants (Competibacter in 11 plants, Defluviicoccus in 6 plants) and were consistent in only a few plants. This shows that these were not core species in the EBPR communities. The total GAO abundance was always lower than that of Accumulibacter. In plants without EBPR design, the abundance of PAO and GAO was significantly lower. Competibacter correlated in general with high fraction of industrial wastewater. In specific plants Accumulibacter correlated with high C/P ratio of the wastewater and Tetrasphaera with high organic loading. Interestingly, the relative microbial composition of the PAO/GAO species was unique to each plant over time, which gives a characteristic plant-specific "fingerprint". Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Evaluate Factors Limiting Columbia River Gorge Chum Salmon Populations : FY2001 Annual Report.

    SciTech Connect

    Hoffman, Thomas A.

    2001-12-01

    Juvenile and adult chum salmon were monitored in fiscal year 2001 to continue evaluating factors limiting production. Total adult salmon caught (in weirs or by carcass surveys) in Hardy Creek and Hamilton Springs in 2000 was 25 and 130 fish, respectively. Fifty-two fish captured in the main stem Columbia River, Hamilton Springs, Hardy Creek, or Bonneville Dam were implanted with radio tags and tracked with an array of fixed aerials and underwater antennae. Males tended to move greater distances than females. Population estimates in Hardy Creek and Hamilton Springs were 37{+-}2 and 157{+-}5, respectively. Chum smolt emigration began in Hamilton Springs 25 February 2001 and 2 March 2001 in Hardy Creek. Total catches in Hardy Creek and Hamilton Springs were 2,955 and 14,967, respectively. Population abundance estimates were 11,586{+-}1,836 in Hardy Creek and 84,520{+-}9,283 in Hamilton Springs.

  5. Wood mouse and box turtle populations in an area treated annually with DDT for five years

    USGS Publications Warehouse

    Stickel, L.F.

    1951-01-01

    A 117-acre area of dense woodland on the Patuxent Research Refuge received an aerial application of DDT in oil at the rate of 2 pounds per acre gnnually for five years. DDT reached ground level in a much smaller amount (thousandths to hundredths of a pound per acre). Treatment was made during the first week of June of each year from 1945 through 1949. Field studies of the wood mouse population in DDT and check areas showed no significant differences in the two areas before and after the 1949 DDT treatment. There was no significant difference between trapping samples taken in DDT and check areas in 1945 and those taken in 1949. Field studies of the box turtles in DDT and check areas in 1945 and 1949 showed no significant difference in population size. Growth of the four young turtles taken in the DDT area in both 1945 and 1949 appeared to be normal in comparison with growth of check area turtles.

  6. Annual Changes of Paddy Rice Planting Areas in Northeastern Asia from MODIS images in 2000-2014

    NASA Astrophysics Data System (ADS)

    Xiao, X.; Zhang, G.; Dong, J.; Menarguez, M. A.; Kou, W.; Jin, C.; Qin, Y.; Zhou, Y.; Wang, J.; Moore, B., III

    2014-12-01

    Knowledge of the area and spatial distribution of paddy rice is important for assessment of food security, management of water resources, estimation of greenhouse gas (methane) emissions, and understanding avian influenza virus transmission. Over the past two decades, paddy rice cultivation has expanded northward in temperate and cold temperate zones, particularly in Northeastern China. There is a need to quantify and map changes in paddy rice planting areas in Northeastern Asia (Japan, North and South Korea, and northeast China) at annual interval. We developed a pixel- and phenology-based image analysis system, MODIS-RICE, to map the paddy rice in Northeastern Asia by using multi-temporal MODIS thermal and surface reflectance imagery. Paddy rice fields during the flooding and transplanting phases have unique physical and spectral characteristics, which make it possible for the development of an automated and robust algorithm to track flooding and transplanting phases of paddy rice fields over time. In this presentation, we will show the MODIS-based annual maps of paddy rice planting area in the Northeastern Asia from 2000-2014 (500-m spatial resolution). Accuracy assessments using high-resolution images show that the resultant paddy rice map of Northeastern Asia had a comparable accuracy to the existing products, including 2010 Landsat-based National Land Cover Dataset (NLCD) of China, the 2010 RapidEye-based paddy rice map in North Korea, and the 2010 AVNIR-2-based National Land Cover Dataset in Japan in terms of both area and spatial pattern of paddy rice. This study has demonstrated that our novel MODIS-Rice system, which use both thermal and optical MODIS data over a year, are simple and robust tools to identify and map paddy rice fields in temperate and cold temperate zones.

  7. Genetic diversity of high-elevation populations of an endangered medicinal plant

    PubMed Central

    Nag, Akshay; Ahuja, Paramvir Singh; Sharma, Ram Kumar

    2015-01-01

    Intraspecific genetic variation in natural populations governs their potential to overcome challenging ecological and environmental conditions. In addition, knowledge of this variation is critical for the conservation and management of endangered plant taxa. Found in the Himalayas, Podophyllum hexandrum is an endangered high-elevation plant species that has great medicinal importance. Here we report on the genetic diversity analysis of 24 P. hexandrum populations (209 individuals), representing the whole of the Indian Himalayas. In the present study, seven amplified fragment length polymorphism (AFLP) primer pairs generated 1677 fragments, of which 866 were found to be polymorphic. Neighbour joining clustering, principal coordinate analysis and STRUCTURE analysis clustered 209 individuals from 24 populations of the Indian Himalayan mountains into two major groups with a significant amount of gene flow (Nm = 2.13) and moderate genetic differentiation Fst(0.196), G′st(0.20). This suggests that, regardless of geographical location, all of the populations from the Indian Himalayas are intermixed and are composed broadly of two types of genetic populations. High variance partitioned within populations (80 %) suggests that most of the diversity is restricted to the within-population level. These results suggest two possibilities about the ancient population structure of P. hexandrum: either all of the populations in the geographical region of the Indian Himalayas are remnants of a once-widespread ancient population, or they originated from two types of genetic populations, which coexisted a long time ago, but subsequently separated as a result of long-distance dispersal and natural selection. High variance partitioned within the populations indicates that these populations have evolved in response to their respective environments over time, but low levels of heterozygosity suggest the presence of historical population bottlenecks. PMID:25416728

  8. Host-plant-associated genetic differentiation in Northern French populations of the European corn borer.

    PubMed

    Martel, C; Réjasse, A; Rousset, F; Bethenod, M-T; Bourguet, D

    2003-02-01

    The phytophagous insects that damage crops are often polyphagous, feeding on several types of crop and on weeds. The refuges constituted by noncrop host plants may be useful in managing the evolution in pest species of resistance to the Bacillus thuringiensis toxins produced by transgenic crops. However, the benefits of these refuges may be limited because host-plant diversity may drive genetic divergence and possibly even host-plant-mediated sympatric speciation. The European corn borer, Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), is the main pest of maize in Europe and North America, where it was introduced early in the 20th century. It has a wide host range but feeds principally on mugwort (Artemisia vulgaris L.) and maize (Zea mays L.). O. nubilalis is found on mugwort only in the northern part of France, whereas it is found on maize throughout France. The extent of genetic variation at allozyme markers was investigated in populations collected from the two host plants over the entire geographical distribution of the European corn borer on mugwort in France. Allelic differentiation between pairs of populations and hierarchical analyses of pools of samples from each host plant indicate that the group of populations feeding on maize differed from the group of populations feeding on mugwort. Our results suggest (1) host-plant-related divergent selection at the genomic region surrounding the Mpi locus and (2) limited gene flow between the populations feeding on mugwort and those infesting maize fields. These data indicate that adults emerging from mugwort would not be useful for managing the evolution of resistance to the B. thuringiensis toxins in European corn borer populations.

  9. Host-plant dependent population genetics of the invading weevil Hypera postica.

    PubMed

    Iwase, S-I; Nakahira, K; Tuda, M; Kagoshima, K; Takagi, M

    2015-02-01

    Population genetics of invading pests can be informative for understanding their ecology. In this study, we investigated population genetics of the invasive alfalfa weevil Hypera postica in Fukuoka Prefecture, Japan. We analyzed mitochondrial tRNALeu-COII, nuclear EF-1α gene fragments, and Wolbachia infection in relation to three leguminous host plants: Vicia angustifolia, Vicia villosa, and a new host Astragalus sinicus cultivated as a honey source and green manure crop. A parsimony network generated from mitochondrial gene sequences uncovered two major haplotypic groups, Western and Egyptian. In contrast to reported Wolbachia infection of the Western strain in the United States, none of our analyzed individuals were infected. The absence of Wolbachia may contribute to the stable coexistence of mitochondrial strains through inter-strain reproductive compatibility. Hypera postica genetic variants for the mitochondrial and nuclear genes were associated neither with host plant species nor with two geographic regions (Hisayama and Kama) within Fukuoka. Mitochondrial haplogroups were incongruent with nuclear genetic variants. Genetic diversity at the nuclear locus was the highest for the populations feeding on V. angustifolia. The nuclear data for A. sinicus-feeding populations indicated past sudden population growth and extended Bayesian skyline plot analysis based on the mitochondrial and nuclear data showed that the growth of A. sinicus-feeding population took place within the past 1000 years. These results suggest a shorter history of A. sinicus as a host plant compared with V. angustifolia and a recent rapid growth of H. postica population using the new host A. sinicus.

  10. Marine biomass program: plant breeding and genetics. Annual report, September 1984-December 1985

    SciTech Connect

    Neushul, M.; Harger, B.W.W.; Lewis, R.J.

    1986-03-01

    By building on past efforts and adding to the data base that has been assembled, and through collaborative research with others, progress has been made toward the long-term goal of growing macroalgae in the sea as a future source of substitute natural gas. It is encouraging that the authors program is being emulated in Japan and Sweden, and that there is growing interest in using the unique GRI kelp seedstock collection by workers in Germany, Japan, Alaska, Oregon, California, and elsewhere. This annual report discusses progress made in propagating kelps, and the floating gulf-weed, Sargassum. Work on kelp genetics has revealed high levels of compatability between species and genera, based on 166 hybridization tests.

  11. Genetic Diversity and Population Structure in Polygonum cespitosum: Insights to an Ongoing Plant Invasion

    PubMed Central

    Matesanz, Silvia; Theiss, Kathryn E.; Holsinger, Kent E.; Sultan, Sonia E.

    2014-01-01

    Molecular markers can help elucidate how neutral evolutionary forces and introduction history contribute to genetic variation in invaders. We examined genetic diversity, population structure and colonization patterns in the invasive Polygonum cespitosum, a highly selfing, tetraploid Asian annual introduced to North America. We used nine diploidized polymorphic microsatellite markers to study 16 populations in the introduced range (northeastern North America), via the analyses of 516 individuals, and asked the following questions: 1) Do populations have differing levels of within-population genetic diversity? 2) Do populations form distinct genetic clusters? 3) Does population structure reflect either geographic distances or habitat similarities? We found low heterozygosity in all populations, consistent with the selfing mating system of P. cespitosum. Despite the high selfing levels, we found substantial genetic variation within and among P. cespitosum populations, based on the percentage of polymorphic loci, allelic richness, and expected heterozygosity. Inferences from individual assignment tests (Bayesian clustering) and pairwise FST values indicated high among-population differentiation, which indicates that the effects of gene flow are limited relative to those of genetic drift, probably due to the high selfing rates and the limited seed dispersal ability of P. cespitosum. Population structure did not reflect a pattern of isolation by distance nor was it related to habitat similarities. Rather, population structure appears to be the result of the random movement of propagules across the introduced range, possibly associated with human dispersal. Furthermore, the high population differentiation, genetic diversity, and fine-scale genetic structure (populations founded by individuals from different genetic sources) in the introduced range suggest that multiple introductions to this region may have occurred. High genetic diversity may further contribute to the

  12. The Limits of Mean-Field Heterozygosity Estimates under Spatial Extension in Simulated Plant Populations

    PubMed Central

    Kitchen, James L.; Allaby, Robin G.

    2012-01-01

    Computational models of evolutionary processes are increasingly required to incorporate multiple and diverse sources of data. A popular feature to include in population genetics models is spatial extension, which reflects more accurately natural populations than does a mean field approach. However, such models necessarily violate the mean field assumptions of classical population genetics, as do natural populations in the real world. Recently, it has been questioned whether classical approaches are truly applicable to the real world. Individual based models (IBM) are a powerful and versatile approach to achieve integration in models. In this study an IBM was used to examine how populations of plants deviate from classical expectations under spatial extension. Populations of plants that used three different mating strategies were placed in a range of arena sizes giving crowded to sparse occupation densities. Using a measure of population density, the pollen communication distance (Pcd), the deviation exhibited by outbreeding populations differed from classical mean field expectations by less than 5% when Pcd was less than 1, and over this threshold value the deviation significantly increased. Populations with an intermediate mating strategy did not have such a threshold and deviated directly with increasing isolation between individuals. Populations with a selfing strategy were influenced more by the mating strategy than by increased isolation. In all cases pollen dispersal was more influential than seed dispersal. The IBM model showed that mean field calculations can be reasonably applied to natural outbreeding plant populations that occur at a density in which individuals are less than the average pollen dispersal distance from their neighbors. PMID:22952655

  13. No Genetic Diversity at Molecular Markers and Strong Phenotypic Plasticity in Populations of Ranunculus nodiflorus, an Endangered Plant Species in France

    PubMed Central

    Noel, Florence; Machon, Nathalie; Porcher, Emmanuelle

    2007-01-01

    Background and Aims Although conservation biology has long focused on population dynamics and genetics, phenotypic plasticity is likely to play a significant role in population viability. Here, an investigation is made into the relative contribution of genetic diversity and phenotypic plasticity to the phenotypic variation in natural populations of Ranunculus nodiflorus, a rare annual plant inhabiting temporary puddles in the Fontainebleau forest (Paris region, France) and exhibiting metapopulation dynamics. Methods The genetic diversity and phenotypic plasticity of quantitative traits (morphological and fitness components) were measured in five populations, using a combination of field measurements, common garden experiments and genotyping at microsatellite loci. Key Results It is shown that populations exhibit almost undetectable genetic diversity at molecular markers, and that the variation in quantitative traits observed among populations is due to a high level of phenotypic plasticity. Despite the lack of genetic diversity, the natural population of R. nodiflorus exhibits large population sizes and does not appear threatened by extinction; this may be attributable to large phenotypic plasticity, enabling the production of numerous seeds under a wide range of environmental conditions. Conclusions Efficient conservation of the populations can only be based on habitat management, to favour the maintenance of microenvironmental variation and the resulting strong phenotypic plasticity. In contrast, classical actions aiming to improve genetic diversity are useless in the present case. PMID:17468109

  14. No genetic diversity at molecular markers and strong phenotypic plasticity in populations of Ranunculus nodiflorus, an endangered plant species in France.

    PubMed

    Noel, Florence; Machon, Nathalie; Porcher, Emmanuelle

    2007-06-01

    Although conservation biology has long focused on population dynamics and genetics, phenotypic plasticity is likely to play a significant role in population viability. Here, an investigation is made into the relative contribution of genetic diversity and phenotypic plasticity to the phenotypic variation in natural populations of Ranunculus nodiflorus, a rare annual plant inhabiting temporary puddles in the Fontainebleau forest (Paris region, France) and exhibiting metapopulation dynamics. The genetic diversity and phenotypic plasticity of quantitative traits (morphological and fitness components) were measured in five populations, using a combination of field measurements, common garden experiments and genotyping at microsatellite loci. It is shown that populations exhibit almost undetectable genetic diversity at molecular markers, and that the variation in quantitative traits observed among populations is due to a high level of phenotypic plasticity. Despite the lack of genetic diversity, the natural population of R. nodiflorus exhibits large population sizes and does not appear threatened by extinction; this may be attributable to large phenotypic plasticity, enabling the production of numerous seeds under a wide range of environmental conditions. Efficient conservation of the populations can only be based on habitat management, to favour the maintenance of microenvironmental variation and the resulting strong phenotypic plasticity. In contrast, classical actions aiming to improve genetic diversity are useless in the present case.

  15. [Effects of host plants on the life table parameters of experimental populations of Aphis gossypii].

    PubMed

    Li, Yan-Yan; Zhou, Xiao-Rong; Pang, Bao-Ping; Chang, Jing

    2013-05-01

    A comparative study was conducted on the life table parameters of Aphis gossypii reared on five host plant species at (25 +/- 1) degrees C in laboratory. There existed significant differences in the durations of various developmental stages, adult longevity, mean offspring number per day, net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time, and population doubling time for the A. gossypii populations reared on the host plants. For the aphids on Lagenaria siceraria var. turbinate, they needed the longest time (5.84 days) to complete one generation, but for those on the other four plants, no significant differences were observed, with the time needed ranged from 5.24 to 5.45 days. The adult longevity was the longest (20.04 days) on Cucumis sativus, but had no significant differences on the other four host plants, being from 14.76 to 16.03 days. The populations' survival curves on all test host plants were of Deevey I, i. e., the death mainly occurred during late period. The survival rate on C. sativus was higher than those on the other four host plants. Based on the intrinsic rates of increase of A. gossypii, its host suitability was in the order of Cucumis melo var. saccharinus > Lagenaria siceraria var. turbinate > Cucurbita moschata var. melonaeformis > Cucumis sativus > Cucurbita pepo var. medullosa.

  16. Extinction rate estimates for plant populations in revisitation studies: Importance of detectability

    USGS Publications Warehouse

    Kery, M.

    2004-01-01

    Many researchers have obtained extinction-rate estimates for plant populations by comparing historical and current records of occurrence. A population that is no longer found is assumed to have gone extinct. Extinction can then be related to characteristics of these populations, such as habitat type, size, or species, to test ideas about what factors may affect extinction. Such studies neglect the fact that a population may be overlooked, however, which may bias estimates of extinction rates upward. In addition, if populations are unequally detectable across groups to be compared, such as habitat type or population size, comparisons become distorted to an unknown degree. To illustrate the problem, I simulated two data sets, assuming a constant extinction rate, in which populations occurred in different habitats or habitats of different size and these factors affected their detectability The conventional analysis implicitly assumed that detectability equalled 1 and used logistic regression to estimate extinction rates. It wrongly identified habitat and population size as factors affecting extinction risk. In contrast, with capture-recapture methods, unbiased estimates of extinction rates were recovered. I argue that capture-recapture methods should be considered more often in estimations of demographic parameters in plant populations and communities.

  17. After Mexico: NGOs and the Follow-Up to the International Conference on Population. Summary Report of the Annual NGO/UNFPA Consultation on Population in New York (4th, Church Centre, New York, March 6, 1985).

    ERIC Educational Resources Information Center

    Cassidy, Kevin, Ed.

    This document consists of three parts. Part I is a summary report of the Fourth Annual Non-Governmental Organizations/United Nations Fund for Population Activities (NGO/UNFPA) Consultation on Population. It includes: an opening statement by David Poindexter; presentations by Bradman Weerakoon ("Opportunities for Action") and Sheldon Segal ("Global…

  18. After Mexico: NGOs and the Follow-Up to the International Conference on Population. Summary Report of the Annual NGO/UNFPA Consultation on Population in New York (4th, Church Centre, New York, March 6, 1985).

    ERIC Educational Resources Information Center

    Cassidy, Kevin, Ed.

    This document consists of three parts. Part I is a summary report of the Fourth Annual Non-Governmental Organizations/United Nations Fund for Population Activities (NGO/UNFPA) Consultation on Population. It includes: an opening statement by David Poindexter; presentations by Bradman Weerakoon ("Opportunities for Action") and Sheldon Segal ("Global…

  19. Health impacts of large releases of radionuclides. Impacts on plant and animal populations.

    PubMed

    Whicker, F W

    1997-01-01

    Historical experiments and observations in radioactively contaminated environments have documented radiation impacts on natural plant communities and animal populations. General findings from these studies are reviewed. Despite much information on the response of individual organisms to radiation in the laboratory, the database is more limited and the interpretations more complex for natural populations and communities exposed to radionuclides. These complications are discussed as they pertain to plants and animals in natural environments. Paradigms concerning the recovery of radiation-damaged communities and ecosystems, and areas of needed research are discussed.

  20. Correlation between annual volume of cystectomy, professional staffing, and outcomes: a statewide, population-based study.

    PubMed

    Elting, Linda S; Pettaway, Curtis; Bekele, B Nebiyou; Grossman, H Barton; Cooksley, Catherine; Avritscher, Elenir B C; Saldin, Kamaldeen; Dinney, Colin P N

    2005-09-01

    The association between high procedure volume and lower perioperative mortality is well established among cancer patients who undergo cystectomy. However, to the authors' knowledge, the association between volume and perioperative complications has not been studied to date and hospital characteristics contributing to the volume-outcome correlation are unknown. In the current study, the authors studied these associations, emphasizing hospital factors that contribute to the volume-outcome correlation. Multiple-variable models of inpatient mortality and complications were developed among all 1302 bladder carcinoma patients who underwent cystectomy between January 1, 1999 and December 31, 2001 in all Texas hospitals. General estimating equations were used to adjust for clustering within the 133 hospitals. Data were obtained from hospital claims, the 2000 U.S. Census, and databases from the Center for Medicare and Medicaid Services and the American Hospital Association. Complications were reported to occur in 12% of patients, 2.2% of whom died. Mortality was higher in low-volume hospitals compared with high-volume hospitals (3.1% vs. 0.7%; P < 0.001); mortality in moderate-volume hospitals was reported to be intermediate (2.9%). After adjustment for advanced age and comorbid conditions, treatment in high-volume hospitals was associated with lower risks of mortality (odds ratio [OR] = 0.35; P = 0.02) and complications (OR = 0.53; P = 0.01). Hospitals with a high registered nurse-to-patient ratio also had a lower mortality risk (OR = 0.43; P = 0.04). Mortality after cystectomy was found to be significantly lower in high-volume hospitals, regardless of patient age. Referral to a hospital performing greater than 10 cystectomies annually is indicated for all patients. However, patients with poor access to a high-volume hospital may derive similar benefit from treatment at a hospital with a high-registered nurse-to-patient ratio. This finding requires further confirmation.

  1. Dynamics of a deep-water seagrass population on the Great Barrier Reef: annual occurrence and response to a major dredging program

    PubMed Central

    York, Paul H.; Carter, Alex B.; Chartrand, Kathryn; Sankey, Tonia; Wells, Linda; Rasheed, Michael A.

    2015-01-01

    Global seagrass research efforts have focused on shallow coastal and estuarine seagrass populations where alarming declines have been recorded. Comparatively little is known about the dynamics of deep-water seagrasses despite evidence that they form extensive meadows in some parts of the world. Deep-water seagrasses are subject to similar anthropogenic threats as shallow meadows, particularly along the Great Barrier Reef lagoon where they occur close to major population centres. We examine the dynamics of a deep-water seagrass population in the GBR over an 8 year period during which time a major capital dredging project occurred. Seasonal and inter-annual changes in seagrasses were assessed as well as the impact of dredging. The seagrass population was found to occur annually, generally present between July and December each year. Extensive and persistent turbid plumes from a large dredging program over an 8 month period resulted in a failure of the seagrasses to establish in 2006, however recruitment occurred the following year and the regular annual cycle was re-established. Results show that despite considerable inter annual variability, deep-water seagrasses had a regular annual pattern of occurrence, low resistance to reduced water quality but a capacity for rapid recolonisation on the cessation of impacts. PMID:26279474

  2. Lake Roosevelt Fisheries Evaluation Program, Part A; Fisheries Creel Survey and Population Status Analysis, 1998 Annual Report.

    SciTech Connect

    Spotts, Jim; Shields, John; Underwood, Keith

    2002-05-01

    The Lake Roosevelt Fisheries Evaluation Program is the result of a merger between two projects, the Lake Roosevelt Monitoring Program (BPA No. 8806300) and the Lake Roosevelt Data Collection Project (BPA No. 9404300). These projects were merged in 1996 to continue work historically completed under the separate projects, and is now referred to as the Lake Roosevelt Fisheries Evaluation Program. Creel and angler surveys estimated that anglers made 196,775 trips to Lake Roosevelt during 1998, with an economic value of $8.0 million dollars, based on the Consumer Price Index (CPI). In 1998 it was estimated that 9,980 kokanee salmon, 226,809 rainbow trout, 119,346 walleye, and over 14,000 smallmouth bass and other species were harvested. Creel data indicates that hatchery reared rainbow trout contribute substantially to the Lake Roosevelt fishery. The contribution of kokanee salmon to the creel has not met the expectations of fishery managers to date, and is limited by entrainment from the reservoir, predation, and possible fish culture obstacles. The 1998 Lake Roosevelt Fisheries Creel and Population Analysis Annual Report includes analyses of the relative abundance of fish species, and reservoir habitat relationships (1990-1998). Fisheries surveys (1990-1998) indicate that walleye and burbot populations appear to be increasing, while yellow perch, a preferred walleye prey species, and other prey species are decreasing in abundance. The long term decreasing abundance of yellow perch and other prey species are suspected to be the result of the lack of suitable multiple reservoir elevation spawning and rearing refugia for spring spawning reservoir prey species, resulting from seasonal spring-early summer reservoir elevation manipulations, and walleye predation. Reservoir water management is both directly, and indirectly influencing the success of mitigation hatchery production of kokanee salmon and rainbow trout. Tag return data suggested excessive entrainment occurred in

  3. Paducah Gaseous Diffusion Plant Annual Site Environmental Report summary for 1993

    SciTech Connect

    Not Available

    1994-11-01

    This report contains summaries of the environmental programs at Paducah Gaseous Diffusion Plant, environmental monitoring and the results, and the impact of operations on the environment and the public for 1993. The environmental monitoring program at Paducah includes effluent monitoring and environmental surveillance. Effluent monitoring is measurement of releases as they occur. Contaminants are released through either airborne emissions or liquids discharged from the plant. These releases occur as part of normal site operations, such as cooling water discharged from the uranium enrichment cascade operations or airborne releases from ventilation systems. In the event of system failure, this monitoring provides timely warning so that corrective action can be taken before releases reach an unsafe level. Environmental surveillance tracks the dispersion of materials into the environment after they have been released. This involves the collection of samples from various media, such as water, soil, vegetation, and food crops, and the analysis of these samples for certain radionuclides, chemicals, and metals.

  4. Portsmouth Gaseous Diffusion Plant Annual Site Environmental Report summary for 1993

    SciTech Connect

    Not Available

    1994-11-01

    This report contains summaries of the environmental programs at Paducah Gaseous Diffusion Plant, environmental monitoring and the results, and the impact of operations on the environment and the public for 1993. The environmental monitoring program at Paducah includes effluent monitoring and environmental surveillance. Effluent monitoring is measurement of releases as they occur. Contaminants are released through either airborne emissions or liquids discharged from the plant. These releases occur as part of normal site operations, such as cooling water discharged from the uranium enrichment cascade operations or airborne releases from ventilation systems. In the event of system failure, this monitoring provides timely warning so that corrective action can be taken before releases reach an unsafe level. Environmental surveillance tracks the dispersion of materials into the environment after they have been released. This involves the collection of samples from various media, such as water, soil, vegetation, and food crops, and the analysis of these samples for certain radionuclides, chemicals, and metals.

  5. Enhancing nuclear power plant performance through the use of artifical intelligence. First annual report

    SciTech Connect

    Johnson, M.; Maren, A.; Miller, L.; Uhrig, R.; Upadhyaya, B.

    1989-06-15

    In the summer of 1988, the Department of Nuclear Engineering (NE) at the University of Tennessee (UT) in Knoxville was selected to carry out a research program in ``Enhancing the Operation of Nuclear Power plants through the use of Artificial Intelligence, This program is sponsored by the Department of Energy`s Office of Energy Research under 10CFR605 for Nuclear Engineering Research. The objective of the research is to advance the state-of-the-art of nuclear power plant control, safety, management, and instrumentation systems through the use of artificial intelligence (AI) techniques, including both expert systems and neural networks. The emphasis will be placed on methods that can be implemented on a rapid or real-time basis. A second, but equally important, objective is to build a broadly based critical mass of expertise in the artificial intelligence, field that can be brought to bear on the technology of nuclear power plants. Both of these goals are being met. This overview and the attached technical reports describe the work that is being carried out. Although in some cases, the scope of the work differs somewhat from the specific tasks described in the original proposal, all activities are clearly within the overall scope of the contract.

  6. Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming.

    PubMed

    Xue, Kai; Yuan, Mengting M; Xie, Jianping; Li, Dejun; Qin, Yujia; Hale, Lauren E; Wu, Liyou; Deng, Ye; He, Zhili; Van Nostrand, Joy D; Luo, Yiqi; Tiedje, James M; Zhou, Jizhong

    2016-09-27

    Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened. Global change involves simultaneous alterations, including those caused by climate warming and land management practices (e.g., clipping). Data on the interactive effects of

  7. Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

    DOE PAGES

    Xue, Kai; Yuan, Mengting M.; Xie, Jianping; ...

    2016-09-27

    Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. Withmore » less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened. IMPORTANCE Global change involves simultaneous alterations, including those caused by climate warming and land management practices (e.g., clipping). Data on the

  8. Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

    SciTech Connect

    Xue, Kai; Yuan, Mengting M.; Xie, Jianping; Li, Dejun; Qin, Yujia; Hale, Lauren E.; Wu, Liyou; Deng, Ye; He, Zhili; Van Nostrand, Joy D.; Luo, Yiqi; Tiedje, James M.; Zhou, Jizhong

    2016-09-27

    Clipping (i.e., harvesting aboveground plant biomass) is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened. IMPORTANCE Global change involves simultaneous alterations, including those caused by climate warming and land management practices (e.g., clipping). Data on the interactive

  9. Dworshak Reservoir Kokanee Population Monitoring: Project Progress Report, 1999 Annual Report.

    SciTech Connect

    Maiolie, Melo; Vidergar, Dmitri T.; Harryman, Bill

    2001-08-01

    We used split-beam hydroacoustics and trawling to monitor the kokanee Oncorhynchus nerka population in Dworshak Reservoir during 1999. Estimated abundance of kokanee has continued to increase since the high entrainment losses in the spring of 1996. Based on hydroacoustic surveys, we estimated 1,545,000 kokanee and rainbow trout O. mykiss in Dworshak Reservoir during July 1999. This included 1,144,000 age-0 kokanee (90% CI {+-} 42%), 212,000 age-1 kokanee (90% CI {+-} 15%), and 189,000 age-2 kokanee and stocked rainbow trout (90% CI {+-} 39%). Rainbow trout could not be distinguished from the age-2 kokanee in the echograms since they were of similar size. Age-0 kokanee ranged in length from 40 mm to 90 mm, age-1 from 193 mm to 212 mm, and age-2 kokanee from 219 mm to 336 mm. These sizes indicated kokanee are still growing well. Discharge of water from Dworshak Dam during 1999 did not stop the expansion of the kokanee population based on these results. Counts of spawning kokanee in four tributary streams exceeded 11,000 fish. This index also showed a marked increase from last year's 660 spawning kokanee or the 1997 total of 144 spawning kokanee.

  10. Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique.

    PubMed

    Bartáková, Veronika; Reichard, Martin; Janko, Karel; Polačik, Matej; Blažek, Radim; Reichwald, Kathrin; Cellerino, Alessandro; Bryja, Josef

    2013-09-12

    Intraspecific genetic variation of African fauna has been significantly affected by pronounced climatic fluctuations in Plio-Pleistocene, but, with the exception of large mammals, very limited empirical data on diversity of natural populations are available for savanna-dwelling animals. Nothobranchius furzeri is an annual fish from south-eastern Africa, inhabiting discrete temporary savannah pools outside main river alluvia. Their dispersal is limited and population processes affecting its genetic structure are likely a combination of those affecting terrestrial and aquatic taxa. N. furzeri is a model taxon in ageing research and several populations of known geographical origin are used in laboratory studies. Here, we analysed the genetic structure, diversity, historical demography and temporal patterns of divergence in natural populations of N. furzeri across its entire distribution range. Genetic structure and historical demography of N. furzeri were analysed using a combination of mitochondrial (partial cytochrome b sequences, 687 bp) and nuclear (13 microsatellites) markers in 693 fish from 36 populations. Genetic markers consistently demonstrated strong population structuring and suggested two main genetic groups associated with river basins. The split was dated to the Pliocene (>2 Mya). The northern group inhabits savannah pools across the basin of the intermittent river Chefu in south-western Mozambique and eastern Zimbabwe. The southern group (from southernmost Mozambique) is subdivided, with the River Limpopo forming a barrier (maximum divergence time 1 Mya). A strong habitat fragmentation (isolated temporary pools) is reflected in significant genetic structuring even between adjacent pools, with a major influence of genetic drift and significant isolation-by-distance. Analysis of historical demography revealed that the expansion of both groups is ongoing, supported by frequent founder effects in marginal parts of the range and evidence of secondary

  11. Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique

    PubMed Central

    2013-01-01

    Background Intraspecific genetic variation of African fauna has been significantly affected by pronounced climatic fluctuations in Plio-Pleistocene, but, with the exception of large mammals, very limited empirical data on diversity of natural populations are available for savanna-dwelling animals. Nothobranchius furzeri is an annual fish from south-eastern Africa, inhabiting discrete temporary savannah pools outside main river alluvia. Their dispersal is limited and population processes affecting its genetic structure are likely a combination of those affecting terrestrial and aquatic taxa. N. furzeri is a model taxon in ageing research and several populations of known geographical origin are used in laboratory studies. Here, we analysed the genetic structure, diversity, historical demography and temporal patterns of divergence in natural populations of N. furzeri across its entire distribution range. Results Genetic structure and historical demography of N. furzeri were analysed using a combination of mitochondrial (partial cytochrome b sequences, 687 bp) and nuclear (13 microsatellites) markers in 693 fish from 36 populations. Genetic markers consistently demonstrated strong population structuring and suggested two main genetic groups associated with river basins. The split was dated to the Pliocene (>2 Mya). The northern group inhabits savannah pools across the basin of the intermittent river Chefu in south-western Mozambique and eastern Zimbabwe. The southern group (from southernmost Mozambique) is subdivided, with the River Limpopo forming a barrier (maximum divergence time 1 Mya). A strong habitat fragmentation (isolated temporary pools) is reflected in significant genetic structuring even between adjacent pools, with a major influence of genetic drift and significant isolation-by-distance. Analysis of historical demography revealed that the expansion of both groups is ongoing, supported by frequent founder effects in marginal parts of the range and evidence

  12. Genetic differences among populations in sexual dimorphism: evidence for selection on males in a dioecious plant

    PubMed Central

    YU, Q.; ELLEN, E. D.; WADE, M. J.; DELPH, L. F.

    2011-01-01

    Genetic variation among populations in the degree of sexual dimorphism may be a consequence of selection on one or both sexes. We analysed genetic parameters from crosses involving three populations of the dioecious plant Silene latifolia, which exhibits sexual dimorphism in flower size, to determine whether population differentiation was a result of selection on one or both sexes. We took the novel approach of comparing the ratio of population differentiation of a quantitative trait (QST) to that of neutral genetic markers (FST) for males vs. females. We attributed 72.6% of calyx width variation in males to differences among populations vs. only 6.9% in females. The QST/FST ratio was 4.2 for males vs. 0.4 for females, suggesting that selection on males is responsible for differentiation among populations in calyx width and its degree of sexual dimorphism. This selection may be indirect via genetic correlations with other morphological and physiological traits. PMID:21401772

  13. Range-expanding populations of a globally introduced weed experience negative plant-soil feedbacks.

    PubMed

    Andonian, Krikor; Hierro, José L; Khetsuriani, Liana; Becerra, Pablo; Janoyan, Grigor; Villarreal, Diego; Cavieres, Lohengrin; Fox, Laurel R; Callaway, Ragan M

    2011-01-01

    Biological invasions are fundamentally biogeographic processes that occur over large spatial scales. Interactions with soil microbes can have strong impacts on plant invasions, but how these interactions vary among areas where introduced species are highly invasive vs. naturalized is still unknown. In this study, we examined biogeographic variation in plant-soil microbe interactions of a globally invasive weed, Centaurea solstitialis (yellow starthistle). We addressed the following questions (1) Is Centaurea released from natural enemy pressure from soil microbes in introduced regions? and (2) Is variation in plant-soil feedbacks associated with variation in Centaurea's invasive success? We conducted greenhouse experiments using soils and seeds collected from native Eurasian populations and introduced populations spanning North and South America where Centaurea is highly invasive and noninvasive. Soil microbes had pervasive negative effects in all regions, although the magnitude of their effect varied among regions. These patterns were not unequivocally congruent with the enemy release hypothesis. Surprisingly, we also found that Centaurea generated strong negative feedbacks in regions where it is the most invasive, while it generated neutral plant-soil feedbacks where it is noninvasive. Recent studies have found reduced below-ground enemy attack and more positive plant-soil feedbacks in range-expanding plant populations, but we found increased negative effects of soil microbes in range-expanding Centaurea populations. While such negative feedbacks may limit the long-term persistence of invasive plants, such feedbacks may also contribute to the success of invasions, either by having disproportionately negative impacts on competing species, or by yielding relatively better growth in uncolonized areas that would encourage lateral spread. Enemy release from soil-borne pathogens is not sufficient to explain the success of this weed in such different regions. The

  14. Uncoupling the effects of seed predation and seed dispersal by granivorous ants on plant population dynamics.

    PubMed

    Arnan, Xavier; Molowny-Horas, Roberto; Rodrigo, Anselm; Retana, Javier

    2012-01-01

    Secondary seed dispersal is an important plant-animal interaction, which is central to understanding plant population and community dynamics. Very little information is still available on the effects of dispersal on plant demography and, particularly, for ant-seed dispersal interactions. As many other interactions, seed dispersal by animals involves costs (seed predation) and benefits (seed dispersal), the balance of which determines the outcome of the interaction. Separate quantification of each of them is essential in order to understand the effects of this interaction. To address this issue, we have successfully separated and analyzed the costs and benefits of seed dispersal by seed-harvesting ants on the plant population dynamics of three shrub species with different traits. To that aim a stochastic, spatially-explicit individually-based simulation model has been implemented based on actual data sets. The results from our simulation model agree with theoretical models of plant response dependent on seed dispersal, for one plant species, and ant-mediated seed predation, for another one. In these cases, model predictions were close to the observed values at field. Nonetheless, these ecological processes did not affect in anyway a third species, for which the model predictions were far from the observed values. This indicates that the balance between costs and benefits associated to secondary seed dispersal is clearly related to specific traits. This study is one of the first works that analyze tradeoffs of secondary seed dispersal on plant population dynamics, by disentangling the effects of related costs and benefits. We suggest analyzing the effects of interactions on population dynamics as opposed to merely analyzing the partners and their interaction strength.

  15. Uncoupling the Effects of Seed Predation and Seed Dispersal by Granivorous Ants on Plant Population Dynamics

    PubMed Central

    Arnan, Xavier; Molowny-Horas, Roberto; Rodrigo, Anselm; Retana, Javier

    2012-01-01

    Secondary seed dispersal is an important plant-animal interaction, which is central to understanding plant population and community dynamics. Very little information is still available on the effects of dispersal on plant demography and, particularly, for ant-seed dispersal interactions. As many other interactions, seed dispersal by animals involves costs (seed predation) and benefits (seed dispersal), the balance of which determines the outcome of the interaction. Separate quantification of each of them is essential in order to understand the effects of this interaction. To address this issue, we have successfully separated and analyzed the costs and benefits of seed dispersal by seed-harvesting ants on the plant population dynamics of three shrub species with different traits. To that aim a stochastic, spatially-explicit individually-based simulation model has been implemented based on actual data sets. The results from our simulation model agree with theoretical models of plant response dependent on seed dispersal, for one plant species, and ant-mediated seed predation, for another one. In these cases, model predictions were close to the observed values at field. Nonetheless, these ecological processes did not affect in anyway a third species, for which the model predictions were far from the observed values. This indicates that the balance between costs and benefits associated to secondary seed dispersal is clearly related to specific traits. This study is one of the first works that analyze tradeoffs of secondary seed dispersal on plant population dynamics, by disentangling the effects of related costs and benefits. We suggest analyzing the effects of interactions on population dynamics as opposed to merely analyzing the partners and their interaction strength. PMID:22880125

  16. Herbivory Differentially Affects Plant Fitness in Three Populations of the Perennial Herb Lythrum salicaria along a Latitudinal Gradient.

    PubMed

    Lehndal, Lina; Ågren, Jon

    2015-01-01

    Herbivory can negatively and selectively affect plant fitness by reducing growth, survival and reproductive output, thereby influencing plant population dynamics and evolution. Latitudinal variation in intensity of herbivory is common, but the extent to which it translates into corresponding variation in effects on plant performance is still poorly known. We tested the hypothesis that variation in the fitness-consequences of herbivory mirror differences in intensity of herbivory among three natural populations of the perennial herb Lythrum salicaria along a latitudinal gradient from southern to northernmost Sweden. We documented intensity of herbivory and examined its effect on survival, growth and reproductive output over two years by experimentally removing herbivores with insecticide. The intensity of herbivory and the effects of herbivory on plant fitness were strongest in the southern population, intermediate in the central population and weakest in the northern population. The mean proportion of the leaf area removed ranged from 11% in the southern to 3% in the northern population. Herbivore removal increased plant height 1.5-fold in the southern and 1.2-fold in the central population, the proportion plants flowering 4-fold in the southern and 2-fold in the central population, and seed production per flower 1.6-fold in the southern and 1.2-fold in the central population, but did not affect plant fitness in the northern population. Herbivore removal thus affected the relative fecundity of plants in the three populations: In the control, seed output per plant was 8.6 times higher in the northern population compared to the southern population, whereas after herbivore removal it was 2.5 times higher in the southern population. The results demonstrate that native herbivores may strongly affect the demographic structure of L. salicaria populations and thereby shape geographic patterns of seed production. They further suggest that the strength of herbivore

  17. Population structure and genetic diversity of a medicinal plant species Retama raetam in southern Tunisia.

    PubMed

    Abdellaoui, Raoudha; Yahyaoui, Faouzia; Neffati, Mohamed

    2014-01-15

    Retama raetam is a stem-assimilating, C3, evergreen, medicinal plant species, desert legume common to arid ecosystems around the Mediterranean basin. This study addresses the genetic diversity and relationship among and within three populations collected from different habitats in southern Tunisia by Random Amplified Polymorphic DNA (RAPD). Estimates of the percentage of polymorphic bands, Shannon's diversity information index and Nei's gene diversity index were determined. Results showed that population from the Island Djerba has the lowest Nei's gene diversity; this also was for Shannon diversity index. An analysis of molecular variance indicated that the majority of variation existed within populations (68%) and that there was significant differentiation among populations (phiPT = 0.316, p < 0.001). Genetic distance (phiPT based values) between pairwise populations ranged from 0.098 to 0.505 and the differentiation between pair-wise populations was significant when individual pairs of populations were compared. Based on the coefficient of gene differentiation (Gst), gene flow (Nm) was estimated and was found to vary from 0.490 to 4.609 between pair-wise populations and 1.42 among populations. The results of UPGMA cluster analysis and PCoA analysis indicated that most variation occurred within populations and that genetic differentiation had happened between populations. These findings are important for a better understanding of the adaptive strategy of R. raetam in southern Tunisia and will be useful for conservation managers to work out an effective strategy to protect this important species.

  18. Systems Biology Approaches to Dissecting Plant Cell Wall Biosynthesis Genes in Poplus (JGI Seventh Annual User Meeting 2012: Genomics of Energy and Environment)

    ScienceCinema

    Glass, N Louise [UC Berkeley

    2016-07-12

    N. Louise Glass from the University of California, Berkeley, presents a talk titled "Systems Biology Approaches to Dissecting Plant Cell Wall Biosynthesis Genes in Poplus" at the JGI 7th Annual Users Meeting: Genomics of Energy & Environment Meeting on March 22, 2012 in Walnut Creek, California.

  19. Systems Biology Approaches to Dissecting Plant Cell Wall Biosynthesis Genes in Poplus (JGI Seventh Annual User Meeting 2012: Genomics of Energy and Environment)

    SciTech Connect

    Glass, N Louise

    2012-03-22

    N. Louise Glass from the University of California, Berkeley, presents a talk titled "Systems Biology Approaches to Dissecting Plant Cell Wall Biosynthesis Genes in Poplus" at the JGI 7th Annual Users Meeting: Genomics of Energy & Environment Meeting on March 22, 2012 in Walnut Creek, California.

  20. Strategic Grassland Bird Conservation throughout the Annual Cycle: Linking Policy Alternatives, Landowner Decisions, and Biological Population Outcomes

    PubMed Central

    Drum, Ryan G.; Ribic, Christine A.; Koch, Katie; Lonsdorf, Eric; Grant, Evan; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, David C.; Rideout, Catherine; Sample, David

    2015-01-01

    Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds. PMID:26569108

  1. Strategic Grassland Bird Conservation throughout the annual cycle: Linking policy alternatives, landowner decisions, and biological population outcomes

    USGS Publications Warehouse

    Drum, Ryan G.; Ribic, Christine; Koch, Katie; Lonsdorf, Eric V.; Grant, Edward C.; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, D.C.; Rideout, Catherine; Sample, David W.

    2015-01-01

    Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds.

  2. Persistence of lymphatic filarial infection in the paediatric population of rural community, after six rounds of annual mass drug administrations.

    PubMed

    Sunish, I P; Munirathinam, A; Kalimuthu, M; Ashok Kumar, V; Tyagi, B K

    2014-06-01

    Under the Global Programme to Eliminate Lymphatic Filariasis (LF), mass drug administration (MDA) is being implemented in Tamil Nadu, south India, by the State health machinery. The impact of six annual rounds of MDA using diethylcarbamazine (DEC) with and without albendazole (ALB) on filarial infection (microfilaraemia prevalence-MFP; antigenaemia prevalence-AGP) in paediatric population of 2-9 years was determined in two revenue blocks, with a population of 321 000. After each MDA, 300-400 children were screened for filarial infection. After six MDAs, an overall MFP reduction of 84.67% and 57.95% was observed in DEC+ALB and DEC alone arms, respectively. Corresponding AGP reductions were 72.88% (p < 0.001) and 41.51% (p = 0.023). Observation of microfilaraemic children after six MDAs (0.32% in DEC+ALB; 0.75% in DEC alone), necessitates the need for supplementary control strategies (viz., vector control), in order to achieve the goal of LF elimination. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Strategic Grassland Bird Conservation throughout the Annual Cycle: Linking Policy Alternatives, Landowner Decisions, and Biological Population Outcomes.

    PubMed

    Drum, Ryan G; Ribic, Christine A; Koch, Katie; Lonsdorf, Eric; Grant, Evan; Ahlering, Marissa; Barnhill, Laurel; Dailey, Thomas; Lor, Socheata; Mueller, Connie; Pavlacky, David C; Rideout, Catherine; Sample, David

    2015-01-01

    Grassland bird habitat has declined substantially in the United States. Remaining grasslands are increasingly fragmented, mostly privately owned, and vary greatly in terms of habitat quality and protection status. A coordinated strategic response for grassland bird conservation is difficult, largely due to the scope and complexity of the problem, further compounded by biological, sociological, and economic uncertainties. We describe the results from a collaborative Structured Decision Making (SDM) workshop focused on linking social and economic drivers of landscape change to grassland bird population outcomes. We identified and evaluated alternative strategies for grassland bird conservation using a series of rapid prototype models. We modeled change in grassland and agriculture cover in hypothetical landscapes resulting from different landowner decisions in response to alternative socio-economic conservation policy decisions. Resulting changes in land cover at all three stages of the annual cycle (breeding, wintering, and migration) were used to estimate changes in grassland bird populations. Our results suggest that successful grassland bird conservation may depend upon linkages with ecosystem services on working agricultural lands and grassland-based marketing campaigns to engage the public. With further development, spatial models that link landowner decisions with biological outcomes can be essential tools for making conservation policy decisions. A coordinated non-traditional partnership will likely be necessary to clearly understand and systematically respond to the many conservation challenges facing grassland birds.

  4. Isolating Fungal Pathogens from a Dynamic Disease Outbreak in a Native Plant Population to Establish Plant-Pathogen Bioassays for the Ecological Model Plant Nicotiana attenuata

    PubMed Central

    Schuck, Stefan; Baldwin, Ian T.

    2014-01-01

    The wild tobacco species Nicotiana attenuata has been intensively used as a model plant to study its interaction with insect herbivores and pollinators in nature, however very little is known about its native pathogen community. We describe a fungal disease outbreak in a native N. attenuata population comprising 873 plants growing in an area of about 1500 m2. The population was divided into 14 subpopulations and disease symptom development in the subpopulations was monitored for 16 days, revealing a waxing and waning of visible disease symptoms with some diseased plants recovering fully. Native fungal N. attenuata pathogens were isolated from diseased plants, characterized genetically, chemotaxonomically and morphologically, revealing several isolates of the ascomycete genera Fusarium and Alternaria, that differed in the type and strength of the disease symptoms they caused in bioassays on either detached leaves or intact soil-grown plants. These isolates and the bioassays will empower the study of N. attenuata-pathogen interactions in a realistic ecological context. PMID:25036191

  5. Habitat-specific impacts of multiple consumers on plant population dynamics.

    PubMed

    Maron, John L; Kauffman, Matthew J

    2006-01-01

    Multiple consumers often attack seeds, seedlings, and adult plants, but their population-level consequences remain uncertain. We examined how insect and small mammal consumers influenced the demography and abundance of the perennial shrub, bush lupine (Lupinus arboreus). In grassland and dune habitats we established replicate experimental lupine populations in 81-m2 plots that were either protected from, or exposed to, herbivorous voles and granivorous mice (via fencing) and/or root feeding insects (via insecticide treatment). Populations were initiated with transplanted seedlings in 1999 and 2000. We followed the demography of these cohorts, subsequent generations, and the seed bank for 5.5 years. Voles and insects killed many seedlings in dune (1999 only) and grassland (1999 and 2000) habitats. After 2000, insects and voles had minimal effects on seedling or adult survival. Seed predation by granivorous mice, however, greatly depressed seedling recruitment, resulting in lower adult lupine abundance in control plots vs. those protected from rodents. In grasslands, initial effects of voles and insects on seedling survival produced large differences among treatments in adult plant density and the cumulative number of seeds produced throughout the experiment. Differences among grassland populations in seed rain, however, had little influence on the magnitude of seedling recruitment into this habitat. Instead, recruitment out of a preexisting seed bank compensated for the lack of seed production in populations exposed to consumers. Shading by dense adults in plots protected from consumers limited seedling establishment within these populations. Although differences among populations in cumulative seed rain did not influence adult establishment, populations protected from consumers accumulated substantially larger seed banks than controls. These results illustrate how density dependence, habitat-specific seed dynamics, and particular demographic impacts of consumers

  6. Ploidy frequencies in plants with ploidy heterogeneity: fitting a general gametic model to empirical population data

    PubMed Central

    Suda, Jan; Herben, Tomáš

    2013-01-01

    Genome duplication (polyploidy) is a recurrent evolutionary process in plants, often conferring instant reproductive isolation and thus potentially leading to speciation. Outcome of the process is often seen in the field as different cytotypes co-occur in many plant populations. Failure of meiotic reduction during gametogenesis is widely acknowledged to be the main mode of polyploid formation. To get insight into its role in the dynamics of polyploidy generation under natural conditions, and coexistence of several ploidy levels, we developed a general gametic model for diploid–polyploid systems. This model predicts equilibrium ploidy frequencies as functions of several parameters, namely the unreduced gamete proportions and fertilities of higher ploidy plants. We used data on field ploidy frequencies for 39 presumably autopolyploid plant species/populations to infer numerical values of the model parameters (either analytically or using an optimization procedure). With the exception of a few species, the model fit was very high. The estimated proportions of unreduced gametes (median of 0.0089) matched published estimates well. Our results imply that conditions for cytotype coexistence in natural populations are likely to be less restrictive than previously assumed. In addition, rather simple models show sufficiently rich behaviour to explain the prevalence of polyploids among flowering plants. PMID:23193129

  7. Ultradeep sequencing analysis of population dynamics of virus escape mutants in RNAi-mediated resistant plants.

    PubMed

    Martínez, Fernando; Lafforgue, Guillaume; Morelli, Marco J; González-Candelas, Fernando; Chua, Nam-Hai; Daròs, José-Antonio; Elena, Santiago F

    2012-11-01

    Plant artificial micro-RNAs (amiRs) have been engineered to target viral genomes and induce their degradation. However, the exceptional evolutionary plasticity of RNA viruses threatens the durability of the resistance conferred by these amiRs. It has recently been shown that viral populations not experiencing strong selective pressure from an antiviral amiR may already contain enough genetic variability in the target sequence to escape plant resistance in an almost deterministic manner. Furthermore, it has also been shown that viral populations exposed to subinhibitory concentrations of the antiviral amiR speed up this process. In this article, we have characterized the molecular evolutionary dynamics of an amiR target sequence in a viral genome under both conditions. The use of Illumina ultradeep sequencing has allowed us to identify virus sequence variants at frequencies as low as 2 × 10(-6) and to track their variation in time before and after the viral population was able of successfully infecting plants fully resistant to the ancestral virus. We found that every site in the amiR-target sequence of the viral genome presented variation and that the variant that eventually broke resistance was sampled among the many coexisting ones. In this system, viral evolution in fully susceptible plants results from an equilibrium between mutation and genetic drift, whereas evolution in partially resistant plants originates from more complex dynamics involving mutation, selection, and drift.

  8. Assessment of annual exposure of private farmers to whole body mechanical vibration on selected family farms of plant production profile.

    PubMed

    Solecki, Leszek

    2010-01-01

    The objective of the study was evaluation of an annual exposure of private farmers to whole body mechanical vibration on selected family farms of plant production profile. The study covered 15 family farms, using arable land of the size of 10-50 ha (22.3 ha on average), engaged mainly in plant production, and equipped with tractors, tractor-mounted agricultural machinery, with a partial contribution of self-propelled machines. The scope of the study covered the carrying out of time schedules of agricultural activities, and measurements of effective values (RMS) for vibration acceleration (equivalent), frequency corrected, on the seats of farm vehicles in 3 spatial directions of vibration (X, Y, Z). The measurements were made while performing various basic field and transport work activities during the period of the whole year. The study showed (plant production) that the degree of whole body mechanical vibration load among farmers during the whole year depends on the vibration level and duration of exposure to this factor. The highest values of the total vibration dose (d) occur both during summer-autumn months (August, September, October and November), and in spring (April, May). The mean equivalent of daily vibration acceleration shows the highest values during 4 months of the year: April and May (0.52 m/s(2)), and in August and September (0.56-0.57 m/s(2)); the average value of this parameter, for the whole year, reaches the level of 0.45 m/s(2). Considering the fact of the occurrence of mechanical shocks in agricultural vehicles (high maximum accelerations values registered: 0.81-1.01 m/s(2); standard exceeding), and exceeding of the daily exposure action value, proper steps should be undertaken with respect to the protection of private farmers against risk resulting from exposure to mechanical vibration while performing work activities.

  9. Anthropogenic effects on population genetics of phytophagous insects associated with domesticated plants.

    PubMed

    Alvarez, Nadir; Hossaert-McKey, Martine; Restoux, Gwendal; Delgado-Salinas, Alfonso; Benrey, Betty

    2007-12-01

    The hypothesis of isolation by distance (IBD) predicts that genetic differentiation between populations increases with geographic distance. However, gene flow is governed by numerous factors and the correlation between genetic differentiation and geographic distance is never simply linear. In this study, we analyze the interaction between the effects of geographic distance and of wild or domesticated status of the host plant on genetic differentiation in the bean beetle Acanthoscelides obvelatus. Geographic distance explained most of the among-population genetic differentiation. However, IBD varied depending on the kind of population pairs for which the correlation between genetic differentiation and geographic distance was examined. Whereas pairs of beetle populations associated with wild beans showed significant IBD (P < 10(-4)), no IBD was found when pairs of beetle populations on domesticated beans were examined (P= 0.2992). This latter result can be explained by long-distance migrations of beetles on domesticated plants resulting from human exchanges of bean seeds. Beetle populations associated with wild beans were also significantly more likely than those on domesticated plants to contain rare alleles. However, at the population level, beetles on cultivated beans were similar in allelic richness to those on wild beans. This similarity in allelic richness combined with differences in other aspects of the genetic diversity (i.e., IBD, allelic diversity) is compatible with strongly contrasting effects of migration and drift. This novel indirect effect of human actions on gene flow of a serious pest of a domesticated plant has important implications for the spread of new adaptations such as resistance to pesticides.

  10. Modelling the structural response of cotton plants to mepiquat chloride and population density

    PubMed Central

    Gu, Shenghao; Evers, Jochem B.; Zhang, Lizhen; Mao, Lili; Zhang, Siping; Zhao, Xinhua; Liu, Shaodong; van der Werf, Wopke; Li, Zhaohu

    2014-01-01

    Background and Aims Cotton (Gossypium hirsutum) has indeterminate growth. The growth regulator mepiquat chloride (MC) is used worldwide to restrict vegetative growth and promote boll formation and yield. The effects of MC are modulated by complex interactions with growing conditions (nutrients, weather) and plant population density, and as a result the effects on plant form are not fully understood and are difficult to predict. The use of MC is thus hard to optimize. Methods To explore crop responses to plant density and MC, a functional–structural plant model (FSPM) for cotton (named CottonXL) was designed. The model was calibrated using 1 year's field data, and validated by using two additional years of detailed experimental data on the effects of MC and plant density in stands of pure cotton and in intercrops of cotton with wheat. CottonXL simulates development of leaf and fruits (square, flower and boll), plant height and branching. Crop development is driven by thermal time, population density, MC application, and topping of the main stem and branches. Key Results Validation of the model showed good correspondence between simulated and observed values for leaf area index with an overall root-mean-square error of 0·50 m2 m−2, and with an overall prediction error of less than 10 % for number of bolls, plant height, number of fruit branches and number of phytomers. Canopy structure became more compact with the decrease of leaf area index and internode length due to the application of MC. Moreover, MC did not have a substantial effect on boll density but increased lint yield at higher densities. Conclusions The model satisfactorily represents the effects of agronomic measures on cotton plant structure. It can be used to identify optimal agronomic management of cotton to achieve optimal plant structure for maximum yield under varying environmental conditions. PMID:24489020

  11. Computer aided data acquisition tool for high-throughput phenotyping of plant populations

    PubMed Central

    2009-01-01

    Background The data generated during a course of a biological experiment/study can be sometimes be massive and its management becomes quite critical for the success of the investigation undertaken. The accumulation and analysis of such large datasets often becomes tedious for biologists and lab technicians. Most of the current phenotype data acquisition management systems do not cater to the specialized needs of large-scale data analysis. The successful application of genomic tools/strategies to introduce desired traits in plants requires extensive and precise phenotyping of plant populations or gene bank material, thus necessitating an efficient data acquisition system. Results Here we describe newly developed software "PHENOME" for high-throughput phenotyping, which allows researchers to accumulate, categorize, and manage large volume of phenotypic data. In this study, a large number of individual tomato plants were phenotyped with the "PHENOME" application using a Personal Digital Assistant (PDA) with built-in barcode scanner in concert with customized database specific for handling large populations. Conclusion The phenotyping of large population of plants both in the laboratory and in the field is very efficiently managed using PDA. The data is transferred to a specialized database(s) where it can be further analyzed and catalogued. The "PHENOME" aids collection and analysis of data obtained in large-scale mutagenesis, assessing quantitative trait loci (QTLs), raising mapping population, sampling of several individuals in one or more ecological niches etc. PMID:20003250

  12. A Bioassay for Determining Resistance Levels in Tarnished Plant Bug Populations to Neonicotinoid Insecticides

    USDA-ARS?s Scientific Manuscript database

    A laboratory bioassay was developed and used to test field populations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), for resistance development to the neonicitinoid insecticides imidacloprid (Trimax®) and thiamethoxam (Centric®). The bioassay determined LC50 values by feeding...

  13. Linking native and invader traits explains native spider population responses to plant invasion

    Treesearch

    Jennifer N. Smith; Douglas J. Emlen; Dean E. Pearson

    2016-01-01

    Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to...

  14. Influence of maize and pigweed on tarnished plant bug (Hemiptera: Miridae) populations infesting cotton

    USDA-ARS?s Scientific Manuscript database

    The influence of maize, lea mays L., and pigweed, Amaranthus spp., on populations of tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), adults infesting cotton, Gossypium hirsucum L., in the Mississippi Delta was studied using stable isotope analyses. Cotton fields adjacent to maize and th...

  15. Seasonal and annual reoccurrence in betaproteobacterial ammonia-oxidizing bacterial population structure.

    PubMed

    Bouskill, Nicholas J; Eveillard, Damien; O'Mullan, Gregory; Jackson, George A; Ward, Bess B

    2011-04-01

    Microbes exhibit remarkably high genetic diversity compared with plant and animal species. Many phylogenetically diverse but apparently functionally redundant microbial taxa are detectable within a cubic centimetre of mud or a millilitre of water, and the significance of this diversity, in terms of ecosystem function, has been difficult to understand. Thus it is not known whether temporal and spatial differences in microbial community composition are linked to particular environmental factors or might modulate ecosystem response to environmental change. Fifty-three water and sediment samples from upper and lower Chesapeake Bay were analysed in triplicate arrays to determine temporal and spatial patterns and relationships between ammonia-oxidizing bacterial (AOB) communities and environmental variables. Thirty-three water samples (three depths) collected during April, August and October, 2001-2004, from the oligohaline upper region of the Bay were analysed to investigate temporal patterns in archetype distribution. Using a combination of a non-weighted discrimination analysis and principal components analysis of community composition data obtained from functional gene microarrays, it was found that co-varying AOB assemblages reoccurred seasonally in concert with specific environmental conditions, potentially revealing patterns of niche differentiation. Among the most notable patterns were correlations of AOB archetypes with temperature, DON and ammonium concentrations. Different AOB archetypes were more prevalent at certain times of the year, e.g. some were more abundant every autumn and others every spring. This data set documents the successional return to an indigenous community following massive perturbation (hurricane induced flooding) as well as the seasonal reoccurrence of specific lineages, identified by key functional genes, associated with the biogeochemically important process nitrification.

  16. Dworshak Kokanee Population and Engrainment Assessment : 2006 Annual Report, March 1, 2006 - February 28, 2007.

    SciTech Connect

    Stark, Eric J.

    2008-12-18

    During this contract, we continued testing underwater strobe lights to determine their effectiveness at repelling kokanee Oncorhynchus nerka away from Dworshak Dam. Strobe light tests were conducted on four nights from April 24-27, 2006, in front of the middle reservoir outlet (RO) 2. The density and distribution of fish, (thought to be mostly kokanee), were monitored with a split-beam echo sounder. We then compared fish counts and densities during nights when the lights were flashing to counts and densities during adjacent nights without the lights on. On two nights, April 25 and 27, 2006, when no lights were present, fish counts near RO 2 averaged 12.4 fish and densities averaged 31.0 fish/ha. When strobe lights were turned on during the nights of April 24 and 26, mean counts dropped to 4.7 fish and densities dropped to 0.5 fish/ha. The decline in counts (62%) and densities (99%) was statistically significant (p = 0.009 and 0.002, respectively). Test results indicated that strobe lights were able to reduce fish densities by at least 50% in front of a discharging reservoir outlet, which would be sufficient to improve sport fish harvest. We also used split-beam hydroacoustics to monitor the kokanee population in Dworshak Reservoir during 2006. Estimated abundance of kokanee increased from the 2005 population estimate. Based on hydroacoustic surveys, we estimated approximately 5,815,000 kokanee (90% CI {+-} 27.6%) in Dworshak Reservoir in August 2006. This included 2,183,000 age-0 (90% CI {+-} 24.2%), 1,509,000 age-1 (90% CI {+-} 29.0%), and 2,124,000 age-2 (90% CI {+-} 27.6%) kokanee. This resulted in a density of age-2 kokanee above the management goal of 30-50 adults/ha. Entrainment sampling was conducted with fixed-site, split-beam hydroacoustics from May through September for a continuous 24 h period when dam operations permitted. The highest fish detection rates from entrainment assessments were found during dawn periods, unlike previous year's results, which

  17. Plant regeneration methods for rapid generation of a large scale Ds transposant population in rice.

    PubMed

    Xuan, Yuan Hu; Huang, Jin; Yi, Gihwan; Park, Dong-Soo; Park, Soo Kwon; Eun, Moo Young; Yun, Doh Won; Lee, Gang-Seob; Kim, Tae Ho; Han, Chang-deok

    2013-01-01

    To mutagenize rice genomes, a two-element system is utilized. This system comprises an immobile Ac element driven by the CaMV 35S promoter, and a gene trap Ds carrying a partial intron with alternative splice acceptors fused to the GUS coding region. Rapid, large-scale generation of a Ds transposant population was achieved using a plant regeneration procedure involving the tissue culture of seed-derived calli carrying Ac and Ds elements. During tissue cultures, Ds mobility accompanies changes in methylation patterns of a terminal region of Ds, where over 70% of plants contained independent Ds insertions. In the transposon population, around 12% of plants expressed GUS at the early seedling stage. A flanking-sequence-tag (FST) database has been established by cloning over 19,968 Ds insertion sites and the Ds map shows relatively uniform distribution across the rice chromosomes.

  18. WHIPPET: a novel tool for prioritizing invasive plant populations for regional eradication.

    PubMed

    Skurka Darin, Gina M; Schoenig, Steve; Barney, Jacob N; Panetta, F Dane; DiTomaso, Joseph M

    2011-01-01

    Large geographic areas can have numerous incipient invasive plant populations that necessitate eradication. However, resources are often deficient to address every infestation. Within the United States, weed lists (either state-level or smaller unit) generally guide the prioritization of eradication of each listed species uniformly across the focus region. This strategy has several limitations that can compromise overall effectiveness, which include spending limited resources on 1) low impact populations, 2) difficult to access populations, or 3) missing high impact populations of low priority species. Therefore, we developed a novel science-based, transparent, analytical ranking tool to prioritize weed populations, instead of species, for eradication and tested it on a group of noxious weeds in California. For outreach purposes, we named the tool WHIPPET (Weed Heuristics: Invasive Population Prioritization for Eradication Tool). Using the Analytic Hierarchy Process that included expert opinion, we developed three major criteria, four sub-criteria, and four sub-sub-criteria, taking into account both species and population characteristics. Subject matter experts weighted and scored these criteria to assess the relative impact, potential spread, and feasibility of eradication (major criteria) for 100 total populations of 19 species. Species-wide population scores indicated that conspecific populations do not necessarily group together in the final ranked output. Thus, priority lists based solely on species-level characteristics are less effective compared to a blended prioritization based on both species attributes and individual population and site parameters. WHIPPET should facilitate a more efficacious decision-making process allocating limited resources to target invasive plant infestations with the greatest predicted impacts to the region under consideration. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Evaluate Factors Limiting Columbia River Gorge Chum Salmon Populations; FY 2002 Annual Report.

    SciTech Connect

    Uusitalo, Nancy M.

    2003-01-30

    Adult and juvenile chum salmon were monitored from October 2001 through September 2002 to evaluate factors limiting production. In 2001, 6 and 69 adult chum salmon were captured in the Hardy Creek and Hamilton Springs weirs, respectively. In 2001, 285 and 328 chum salmon carcasses were recovered during spawning ground surveys in Hardy Creek and Hamilton Springs, respectively. Twenty-eight fish captured in the mainstem Columbia River, Hamilton Springs, and Hardy Creek were implanted with radio tags and tracked via an array of fixed aerial, underwater antennas and a mobile tracking unit. Using the Area-Under-the-Curve program population estimates of adult chum salmon were 835 in Hardy Creek and 617 in Hamilton Springs. Juvenile chum salmon migration was monitored from March-June 2002. Total catches for Hardy Creek and Hamilton Springs were 103,315 and 140,220, respectively. Estimates of juvenile chum salmon emigration were 450,195 ({+-}21,793) in Hardy Creek and 561,462 ({+-}21,423) in Hamilton Springs.

  20. Driver's education may reduce annual incidence and severity of moped and scooter accidents. A population-based study.

    PubMed

    Kosola, Silja; Salminen, Päivi; Kallio, Pentti

    2016-01-01

    In our previous study, the annual number of adolescents treated at Helsinki Children's Hospital and Töölö Trauma Centre for injuries from moped and scooter accidents increased five-fold between 2002 and 2007. In June 2011, the requirements for a moped/scooter license changed to include driver's education and a vehicle handling evaluation. The aim of this retrospective study was to assess the influence of legislative changes on moped and scooter related serious injuries in adolescents. Data from 520 patients (age 15-16) treated for trauma from moped and scooter accidents at our institutions between January 2008 and December 2013 were included. Case numbers were compared with population data from national databases. Overall incidence, trauma mechanism, injury profile, and proportion of patients requiring hospital admission were calculated for time periods before and after the law amendment. After the law change in 2011, the annual incidence of moped/scooter injuries among 15-year-olds in our area decreased from 0.8% in 2011 to 0.3% in 2013 (p<0.001), and estimated incidence of injuries per new moped/scooter license declined from 1.8% in 2011 to 1.0% in 2013 (p=0.001). Simultaneously, proportions of patients injured in collisions, diagnosed with multiple trauma or requiring in-patient care reduced. A change in moped/scooter license requirements may have a causal relationship with both reduced number and severity of moped/scooter related injuries in adolescents. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Genetic structure and AFLP variation of remnant populations in the rare plant Pedicularis palustris (Scrophulariaceae) and its relation to population size and reproductive components.

    PubMed

    Schmidt, K; Jensen, K

    2000-05-01

    We investigated plant reproduction in relation to genetic structure, population size, and habitat quality in 13 populations of the rare biennial plant Pedicularis palustris with 3-28500 flowering individuals. We used AFLP (amplified fragment length polymorphism) profiles to analyze genetic similarities among 129 individuals (3-15 per population). In a cluster analysis of genetic similarities most individuals (67%) were arranged in population-specific clusters. Analysis of molecular variance indicated significant genetic differentiation among populations and among and within subpopulations (P < 0.001). Gene flow (N(e) m) was low (0.298). On average, plants produced 55 capsules, 17 seeds per fruit, and 42 seedlings in the following growing season. The number of seeds per capsule was independent of population size and of genetic variability. In contrast, the number of capsules per plant (P < 0.05) and the number of seedlings per plant (P < 0.05) were positively correlated with population size. The relation between population size and the number of seeds per plant was not significant (P = 0.075). The number of capsules and of seeds and seedlings per plant (P < 0.01) were positively correlated with genetic variability. Genetic variability was independent of actual population size, suggesting that historical population processes have to be taken into account, too. Stepwise multiple regressions revealed additional significant relationships of habitat parameters (soil pH, C:N ratio), vegetation composition, and standing crop on reproductive components. We conclude that populations of P. palustris are genetically isolated and that reproductive success most likely is influenced by population size, genetic variability, and habitat quality. Management strategies such as moderate grazing, mowing, and artificial gene flow should endeavor to increase population size as well as genetic variation.

  2. Genetic variation in fitness within a clonal population of a plant RNA virus.

    PubMed

    Cervera, Héctor; Elena, Santiago F

    2016-01-01

    A long-standing observation in evolutionary virology is that RNA virus populations are highly polymorphic, composed by a mixture of genotypes whose abundances in the population depend on complex interaction between fitness differences, mutational coupling and genetic drift. It was shown long ago, though in cell cultures, that most of these genotypes had lower fitness than the population they belong, an observation that explained why single-virion passages turned on Muller's ratchet while very large population passages resulted in fitness increases in novel environments. Here we report the results of an experiment specifically designed to evaluate in vivo the fitness differences among the subclonal components of a clonal population of the plant RNA virus tobacco etch potyvirus (TEV). Over 100 individual biological subclones from a TEV clonal population well adapted to the natural tobacco host were obtained by infectivity assays on a local lesion host. The replicative fitness of these subclones was then evaluated during infection of tobacco relative to the fitness of large random samples taken from the starting clonal population. Fitness was evaluated at increasing number of days post-inoculation. We found that at early days, the average fitness of subclones was significantly lower than the fitness of the clonal population, thus confirming previous observations that most subclones contained deleterious mutations. However, as the number of days of viral replication increases, population size expands exponentially, more beneficial and compensatory mutations are produced, and selection becomes more effective in optimizing fitness, the differences between subclones and the population disappeared.

  3. Rapid regulatory control of plant cell expansion and wall relaxation. Annual technical progress report

    SciTech Connect

    Cosgrove, D.J.

    1991-08-14

    The aim of this project is to elucidate the biophysical and cellular mechanisms that control plant cell expansion. At present we are attempting to characterize the kinetics of the system(s) responsible for regulatory and compensatory behavior of growing cells and tissues. This work is significantly because it indicates that biochemical loosening and biophysical stress relaxation of the wall are part of a feedback loop controlling growth. This report briefly summarizes the efforts and results of the past 12 months. In large part, we have been trying to analyze the nature of growth rate ``noise,`` i.e. spontaneous and often erratic variations in growth rate. We are obtaining evidence that such ``noise`` is not random, but rather reveals an underlying growth mechanism with complex dynamics.

  4. Wood Storks of the birdsville colony and swamps of the Savannah River Plant. Annual report, 1984

    SciTech Connect

    Coulter, M.C.

    1986-01-01

    Studies have been carried out to assess the potential impact of the operation of the Savannah River Plant (SRP) on Wood Storks foraging in the Savannah River Swamp System (SRSS). The objectives were: (1) to determine the locations of foraging sites of Wood Storks from the Birdsville colony and to examine the year-to-year variation in sites used, (2) to characterize in detail the habitat, vegetation, water quality and prey density/biomass at foraging sites, (3) to observe the breeding birds to determine the times when food demands at the colony are greatest, (4) to examine the movement of storks from the rookery to foraging sites and to relate seasonal trends to the breeding biology, (5) to examine the importance of the SRSS to foraging Wood Storks, and (6) to examine the movements of individual birds to determine the generality of the observed patterns. 27 refs., 54 figs., 23 tabs.

  5. Annual Variation in Flowering Phenology, Pollination, Mating System, and Pollen Yield in Two Natural Populations of Schima wallichii (DC.) Korth

    PubMed Central

    Khanduri, Vinod Prasad; Sharma, C. M.; Kumar, K. S.; Ghildiyal, S. K.

    2013-01-01

    Background. Schima wallichii is a highly valuable tree of tropical forest in north-east Himalaya region that grows naturally in a wide range of altitudes between 750 and 2400 m asl with varying environments. Flowering phenology of tropical tree species at population level is generally ignored and therefore a detailed knowledge of flowering and fruiting patterns of important multipurpose tree species is critical to the successful management of forest genetic resources. Materials and Methods. The study was conducted at two different altitudes (i.e., 750 m and 900 m asl) in the tropical semideciduous forest of north-east Himalaya. The floral phenology including flowering synchrony in the populations, anthesis, anther dehiscence, stigma receptivity, pollinators visitation frequency, and mating system including index of self-incompatibility were worked out in Schima wallichii according to the ear-marked standard methods given by various scientists for each parameter. Results. The flowering period in Schima wallichii varied from 33 to 42 days with mean synchrony of 0.54 to 0.68 between the populations. The stigma was receptive up to 2.5 days only and showed slightly protandrous type of dichogamy. Average pollen production ranged between 6.90 × 107 pollen per tree in 2007 and 15.49 × 108 pollen per tree in 2011. A three-year masting cycle was noticed in this species. The frequency of visitation of honey bees was fairly high (5.2 ± 1.12 visits/flower/hour) as compared to other pollinators. The hand pollination revealed maximum fruit (74.2 ± 5.72%) and seed (70.8 ± 7.46%) settings. Conclusions. The variation in flowering phenology and pollen yield individually and annually along with temporal separation in anther dehiscence and pollinator's visitation cause pollen limited reproduction, which ultimately influences the reproductive success in Schima wallichii. PMID:24501577

  6. Forecasting climate change impacts on plant populations over large spatial extents

    USGS Publications Warehouse

    Tredennick, Andrew T.; Hooten, Mevin B.; Aldridge, Cameron; Homer, Collin G.; Kleinhesselink, Andrew R.; Adler, Peter B.

    2016-01-01

    Plant population models are powerful tools for predicting climate change impacts in one location, but are difficult to apply at landscape scales. We overcome this limitation by taking advantage of two recent advances: remotely sensed, species-specific estimates of plant cover and statistical models developed for spatiotemporal dynamics of animal populations. Using computationally efficient model reparameterizations, we fit a spatiotemporal population model to a 28-year time series of sagebrush (Artemisia spp.) percent cover over a 2.5 × 5 km landscape in southwestern Wyoming while formally accounting for spatial autocorrelation. We include interannual variation in precipitation and temperature as covariates in the model to investigate how climate affects the cover of sagebrush. We then use the model to forecast the future abundance of sagebrush at the landscape scale under projected climate change, generating spatially explicit estimates of sagebrush population trajectories that have, until now, been impossible to produce at this scale. Our broadscale and long-term predictions are rooted in small-scale and short-term population dynamics and provide an alternative to predictions offered by species distribution models that do not include population dynamics. Our approach, which combines several existing techniques in a novel way, demonstrates the use of remote sensing data to model population responses to environmental change that play out at spatial scales far greater than the traditional field study plot.

  7. Beyond the Canon: Within-Plant and Population-Level Heterogeneity in Jasmonate Signaling Engaged by Plant-Insect Interactions

    PubMed Central

    Li, Dapeng; Baldwin, Ian T.; Gaquerel, Emmanuel

    2016-01-01

    Plants have evolved sophisticated communication and defense systems with which they interact with insects. Jasmonates are synthesized from the oxylipin pathway and act as pivotal cellular orchestrators of many of the metabolic and physiological processes that mediate these interactions. Many of these jasmonate-dependent responses are tissue-specific and translate from modulations of the canonical jasmonate signaling pathway. Here we provide a short overview of within-plant heterogeneities in jasmonate signaling and dependent responses in the context of plant-insect interactions as illuminated by examples from recent work with the ecological model, Nicotiana attenuata. We then discuss means of manipulating jasmonate signaling by creating tissue-specific jasmonate sinks, and the micrografting of different transgenic plants. The metabolic phenotyping of these manipulations provides an integrative understanding of the functional significance of deviations from the canonical model of this hormonal pathway. Additionally, natural variation in jasmonate biosynthesis and signaling both among and within species can explain polymorphisms in resistance to insects in nature. In this respect, insect-guided explorations of population-level variations in jasmonate metabolism have revealed more complexity than previously realized and we discuss how different “omic” techniques can be used to exploit the natural variation that occurs in this important signaling pathway. PMID:27135234

  8. [Plant growth with limited water]. [Annual report, December 15, 1992--December 14, 1993

    SciTech Connect

    Not Available

    1993-12-01

    We used a soybean seedling system to explore the mechanism of growth limitation by water deficiency (low {Psi}{sub W}). Our prior work had show that (low {Psi}{sub W} inhibited plant growth initially because of a physical limitation to water uptake that appeared to result from a decrease in the {Psi}{sub W} gradient feeding water to the enlarging cells. The gradient was shown to originate from cell wall yielding and was altered primarily at the vascular tissue. In the present grant, we reported the detailed shape of the gradient. We also found that growth could mobilize water from mature tissues in the complete absence of external water using the gradient in {Psi}{sub W}. Growth was maintained by this mobilization. After growth has been inhibited a few hours, metabolic changes occur and a 28kD protein accumulates in the wall fraction of the growth-affected cells. In the present grant, we showed that the mRNA for the protein accumulated in a tissue-specific manner similar to that of the protein, and the accumulation was correlated with the growth response. Other investigators working independently with an acid phosphatase found a deduced amino acid sequence similar to that for the 28kD protein we had published. Biochemical tests showed that the 28kD protein and a related 3lkD protein expressed acid phosphatase activity. We found that the acid phosphatase Of the 28kD protein was in the cell walls of intact plants (in addition to being in the cytoplasm). Current work focuses on the role of this protein. Efforts were made to reverse the growth inhibition at low {Phi}{sub W} by treating growing tissues with low pH buffer, but the protons apparently failed to penetrate the cuticle.

  9. Trade-Offs between the Metabolic Rate and Population Density of Plants

    PubMed Central

    Deng, Jian-Ming; Li, Tao; Wang, Gen-Xuan; Liu, Jing; Yu, Ze-Long; Zhao, Chang-Ming; Ji, Ming-Fei; Zhang, Qiang; Liu, Jian-quan

    2008-01-01

    The energetic equivalence rule, which is based on a combination of metabolic theory and the self-thinning rule, is one of the fundamental laws of nature. However, there is a progressively increasing body of evidence that scaling relationships of metabolic rate vs. body mass and population density vs. body mass are variable and deviate from their respective theoretical values of 3/4 and −3/4 or −2/3. These findings questioned the previous hypotheses of energetic equivalence rule in plants. Here we examined the allometric relationships between photosynthetic mass (Mp) or leaf mass (ML) vs. body mass (β); population density vs. body mass (δ); and leaf mass vs. population density, for desert shrubs, trees, and herbaceous plants, respectively. As expected, the allometric relationships for both photosynthetic mass (i.e. metabolic rate) and population density varied with the environmental conditions. However, the ratio between the two exponents was −1 (i.e. β/δ = −1) and followed the trade-off principle when local resources were limited. Our results demonstrate for the first time that the energetic equivalence rule of plants is based on trade-offs between the variable metabolic rate and population density rather than their constant allometric exponents. PMID:18350139

  10. Dworshak Kokanee Population and Entrainment Assessment 2005-2006 Annual Report.

    SciTech Connect

    Stark, Eric J.

    2008-11-06

    During this contract, we continued testing underwater strobe lights to determine their effectiveness at repelling kokanee Oncorhynchus nerka away from Dworshak Dam. We tested one set of nine strobe lights flashing at a rate of 360 flashes/min in front of turbine 3 while operating at higher discharges than previously tested. The density and distribution of fish, (thought to be mostly kokanee), were monitored with a split-beam echo sounder. We then compared fish counts and densities during nights when the lights were flashing to counts and densities during adjacent nights without the lights on. On five nights between January 31 and February 28, 2006, when no lights were present, fish counts near turbine 3 averaged eight fish and densities averaged 91 fish/ha. When strobe lights were turned on during five adjacent nights during the same period, mean counts dropped to four fish and densities dropped to 35 fish/ha. The decline in counts (49%) was not statistically significant (p = 0.182), but decline in densities (62%) was significant (p = 0.049). There appeared to be no tendency for fish to habituate to the lights during the night. Test results indicated that strobe lights were able to reduce fish densities by at least 50% in front of turbines operating at higher discharges, which would be sufficient to improve sportfish harvest. We also used split-beam hydroacoustics to monitor the kokanee population in Dworshak Reservoir during 2005. Estimated abundance of kokanee decreased from the 2004 population estimate. Based on hydroacoustic surveys, we estimated 3,011,626 kokanee (90% CI {+-} 15.2%) in Dworshak Reservoir, July 2005. This included 2,135,986 age-0 (90% CI {+-} 15.9%), 769,175 age-1 (90% CI {+-} 16.0%), and 107,465 age-2 (90% CI {+-} 15.2%). Poor survival of kokanee from age-1 to age-2 continued to keep age-2 densities below the management goal of 30-50 adults/ha. Entrainment sampling was conducted with fixed-site split-beam hydroacoustics a minimum of two days

  11. Extreme Population-Dependent Linkage Disequilibrium Detected in an Inbreeding Plant Species, Hordeum vulgare

    PubMed Central

    Caldwell, Katherine S.; Russell, Joanne; Langridge, Peter; Powell, Wayne

    2006-01-01

    In human genetics a detailed knowledge of linkage disequilibrium (LD) is considered a prerequisite for effective population-based, high-resolution gene mapping and cloning. Similar opportunities exist for plants; however, differences in breeding system and population history need to be considered. Here we report a detailed study of localized LD in different populations of an inbreeding crop species. We measured LD between and within four gene loci within the region surrounding the hardness locus in three different gene pools of barley (Hordeum vulgare). We demonstrate that LD extends to at least 212 kb in elite barley cultivars but is rapidly eroded in related inbreeding ancestral populations. Our results indicate that haplotype-based sequence analysis in multiple populations will provide new opportunities to adjust the resolution of association studies in inbreeding crop species. PMID:16219791

  12. Assessment of Genetic Heterogeneity in Structured Plant Populations Using Multivariate Whole-Genome Regression Models

    PubMed Central

    Lehermeier, Christina; Schön, Chris-Carolin; de los Campos, Gustavo

    2015-01-01

    Plant breeding populations exhibit varying levels of structure and admixture; these features are likely to induce heterogeneity of marker effects across subpopulations. Traditionally, structure has been dealt with as a potential confounder, and various methods exist to “correct” for population stratification. However, these methods induce a mean correction that does not account for heterogeneity of marker effects. The animal breeding literature offers a few recent studies that consider modeling genetic heterogeneity in multibreed data, using multivariate models. However, these methods have received little attention in plant breeding where population structure can have different forms. In this article we address the problem of analyzing data from heterogeneous plant breeding populations, using three approaches: (a) a model that ignores population structure [A-genome-based best linear unbiased prediction (A-GBLUP)], (b) a stratified (i.e., within-group) analysis (W-GBLUP), and (c) a multivariate approach that uses multigroup data and accounts for heterogeneity (MG-GBLUP). The performance of the three models was assessed on three different data sets: a diversity panel of rice (Oryza sativa), a maize (Zea mays L.) half-sib panel, and a wheat (Triticum aestivum L.) data set that originated from plant breeding programs. The estimated genomic correlations between subpopulations varied from null to moderate, depending on the genetic distance between subpopulations and traits. Our assessment of prediction accuracy features cases where ignoring population structure leads to a parsimonious more powerful model as well as others where the multivariate and stratified approaches have higher predictive power. In general, the multivariate approach appeared slightly more robust than either the A- or the W-GBLUP. PMID:26122758

  13. [Evaluation of non-host plant ethanol extracts against Plutella xylostella population].

    PubMed

    Wei, Hui; Hou, Youming; Yang, Guang; Fu, Jianwei; You, Minsheng

    2005-06-01

    Through establishing experimental and natural population life tables, and by using the index of population trend (1) and interference index of population control (IIPC), this paper evaluated 8 kinds of non-host plant ethanol extracts against experimental population of Plutella xylostella, and 3 kinds of these extracts and their mixture against Plutella xylostella natural population. The experimental population life table of DBM showed that the index of population trend (I) was 69. 8964 in control, and decreased dramatically to 5.3702, 4.4842, 8.0945, 11.1382, 6.8937, 6.1609, 5.5199 and 9.8052, respectively in treatments of Zanthoxylum bungeanum, Eucalyptus tereticornis, Nicotiana tabacum, Broussonetia papyrifera, Bauhinia variegata, Duranta repens, Euphorbia hirta and Camellia oleifera ethanol extracts, while the corresponding IIPC was 0.0768, 0.0642, 0.1158, 0.1594, 0.0986, 0.0881, 0.0790 and 0. 1403, respectively. The natural population life tables of DBM showed that the index of population trend (I) was 21.6232 in control, and decreased dramatically to 5.1997, 7.4160, 7. 3644 and 3.1399, respectively in treatments of the ethanol extracts of E. tereticornis, N. tabacum, C. oleifera and their mixture, while the corresponding IIPC was 0.2405, 0.3695, 0.3549 and 0.1608, respectively. All of these indicated that the test plant extracts could interfere the development of P. xylostella population significantly, and had the potential as an effective measure for controlling insect pest.

  14. Evaluation of Multiplexed 16S rRNA Microbial Population Surveys Using Illumina MiSeq Platform (Seventh Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting 2012)

    ScienceCinema

    Tremblay, Julien [DOE JGI

    2016-07-12

    Julien Tremblay from DOE JGI presents "Evaluation of Multiplexed 16S rRNA Microbial Population Surveys Using Illumina MiSeq Platorm" at the 7th Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting held in June, 2012 in Santa Fe, NM.

  15. Using a full annual cycle model to evaluate long-term population viability of the conservation-reliant Kirtland's warbler after successful recovery

    Treesearch

    Donald J. Brown; Christine A. Ribic; Deahn M. Donner; Mark D. Nelson; Carol I. Bocetti; Christie M. Deloria-Sheffield; Des Thompson

    2017-01-01

    Long-term management planning for conservation-reliant migratory songbirds is particularly challenging because habitat quality in different stages and geographic locations of the annual cycle can have direct and carry-over effects that influence the population dynamics. The Neotropical migratory songbird Kirtland's warbler Setophaga kirtlandii...

  16. Evaluation of Multiplexed 16S rRNA Microbial Population Surveys Using Illumina MiSeq Platform (Seventh Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting 2012)

    SciTech Connect

    Tremblay, Julien

    2012-06-01

    Julien Tremblay from DOE JGI presents "Evaluation of Multiplexed 16S rRNA Microbial Population Surveys Using Illumina MiSeq Platorm" at the 7th Annual Sequencing, Finishing, Analysis in the Future (SFAF) Meeting held in June, 2012 in Santa Fe, NM.

  17. Medicinal plants profile used by the 3rd District population of Maceió-AL.

    PubMed

    Griz, S A S; Matos-Rocha, T J; Santos, A F; Costa, J G; Mousinho, K C

    2017-11-01

    Herein the use of medicinal plants by the population of the 3rd Sanitary District of Maceió-AL city is reported. Transversal description was conducted from February 2013 to January 2014, with a sample of 116 individuals of both Gender Genders aged over 18 years. The ethnobotanical information interviews ethnobotanical information were obtained through semi - structured questionnaire featuring the use of medicinal plants and social and economical data. Descriptive statistics was applied for quantitative variables as mean and standard deviation and proportions for qualitative variables in the frequency table format. The results showed that 85.34% of the interviewees used plants for medicinal purposes. As the majority of these were (73.28%) females in the age group between 30-60 years of old. Among a total of 45 identified plant species, the highest use frequency were for Boldus Peumus (bilberry), Melissa officinalis (lemon balm), and Mentha piperita (mint). The most widely used plant foliage part was (53.53%) prepared as an infusion (55.5%). The use of medicinal plants in Maceió cityis widespread, highlighting the importance of ethnobotanical knowledge for the study of medicinal plants.

  18. Waste Isolation Pilot Plant annual site environmental report for calendar year 1992

    SciTech Connect

    Not Available

    1993-12-31

    The US Department of Energy (DOE) Waste Isolation Pilot Plant (WIPP) Operational Environmental Monitoring Plan (OEMP) defined a comprehensive set of parameters which are monitored to detect potential environmental impacts and establish baselines for future environmental evaluations. Surface water and groundwater, air, soil, and biotics are monitored for radioactivity levels. Nonradiological environmental monitoring activities include air, water quality, soil properties, meteorological measurements and determination of the status of the local biological community. Ecological studies focus on the immediate area surrounding the WIPP site with emphasis on the salt storage pile. The baseline radiological surveillance covers a broader geographic area including nearby ranches, villages, and cities. Since the WIPP is still in its preoperational phase (i.e., no waste has been received) certain operational requirements of DOE Orders 5400.1, 5400.5, and the Environmental Regulatory Guide for Radiological Effluent Monitoring and Environmental Surveillance (DOE/EH-0173T) are not relevant. Therefore, this report does not discuss items such as radionuclide emissions and effluents and subsequent doses to the public.

  19. Annual Medicago: From a Model Crop Challenged by a Spectrum of Necrotrophic Pathogens to a Model Plant to Explore the Nature of Disease Resistance

    PubMed Central

    TIVOLI, B.; BARANGER, A.; SIVASITHAMPARAM, K.; BARBETTI, M. J.

    2006-01-01

    • Background Annual Medicago spp., including M. truncatula, play an important agronomic role in dryland farming regions of the world where they are often an integral component of cropping systems, particularly in regions with a Mediterranean or Mediterranean-type climate where they grow as winter annuals that provide both nitrogen and disease breaks for rotational crops. Necrotrophic foliar and soil-borne pathogens dominate these regions and challenge the productivity of annual Medicago and crop legume species. • Scope This review outlines some of the major and/or widespread diseases these necrotrophic pathogens cause on Medicago spp. It then explores the potential for using the spectrum of necrotrophic pathogen–host interactions, with annual Medicago as the host plant, to better understand and model pathosystems within the diseases caused by nectrotrophic pathogens across forage and grain legume crops. • Conclusions Host resistance clearly offers the best strategy for cost-effective, long-term control of necrotrophic foliar and soil-borne pathogens, particularly as useful resistance to a number of these diseases has been identified. Recently and initially, the annual M. truncatula has emerged as a more appropriate and agronomically relevant substitute to Arabidopsis thaliana as a model plant for legumes, and is proving an excellent model to understand the mechanisms of resistance both to individual pathogens and more generally to most forage and grain legume necrotrophic pathogens. PMID:16803846

  20. Genetic rescue persists beyond first-generation outbreeding in small populations of a rare plant.

    PubMed

    Willi, Yvonne; van Kleunen, Mark; Dietrich, Stefan; Fischer, Markus

    2007-09-22

    Habitat fragmentation commonly causes genetic problems and reduced fitness when populations become small. Stocking small populations with individuals from other populations may enrich genetic variation and alleviate inbreeding, but such artificial gene flow is not commonly used in conservation owing to potential outbreeding depression. We addressed the role of long-term population size, genetic distance between populations and test environment for the performance of two generations of offspring from between-population crosses of the locally rare plant Ranunculus reptans L. Interpopulation outbreeding positively affected an aggregate measure of fitness, and the fitness superiority of interpopulation hybrids was maintained in the second offspring (F2) generation. Small populations benefited more strongly from interpopulation outbreeding. Genetic distance between crossed populations in neutral markers or quantitative characters was not important. These results were consistent under near-natural competition-free and competitive conditions. We conclude that the benefits of interpopulation outbreeding are likely to outweigh potential drawbacks, especially for populations that suffer from inbreeding.

  1. Stability of plant defensive traits among populations in two Eucalyptus species under elevated carbon dioxide.

    PubMed

    McKiernan, Adam B; O'Reilly-Wapstra, Julianne M; Price, Cassandra; Davies, Noel W; Potts, Brad M; Hovenden, Mark J

    2012-02-01

    Plant secondary metabolites (PSMs) mediate a wide range of ecological interactions. Investigating the effect of environment on PSM production is important for our understanding of how plants will adapt to large scale environmental change, and the extended effects on communities and ecosystems. We explored the production of PSMs under elevated atmospheric carbon dioxide ([CO(2)]) in the species rich, ecologically and commercially important genus Eucalyptus. Seedlings from multiple Eucalyptus globulus and E. pauciflora populations were grown in common glasshouse gardens under elevated or ambient [CO(2)]. Variation in primary and secondary chemistry was determined as a function of genotype and treatment. There were clear population differences in PSM expression in each species. Elevated [CO(2)] did not affect concentrations of individual PSMs, total phenolics, condensed tannins or the total oil yield, and there was no population by [CO(2)] treatment interaction for any traits. Multivariate analysis revealed similar results with significant variation in concentrations of E. pauciflora oil components between populations. A [CO(2)] treatment effect was detected within populations but no interactions were found between elevated [CO(2)] and population. These eucalypt seedlings appear to be largely unresponsive to elevated [CO(2)], indicating stronger genetic than environmental (elevated [CO(2)]) control of expression of PSMs.

  2. Impact of drought on plant populations of native and invasive origins.

    PubMed

    Kleine, Sandra; Weissinger, Lisa; Müller, Caroline

    2017-01-01

    Invasive populations often shift phenotypically during introduction. Moreover, they are postulated to show an increased phenotypic plasticity compared with their native counterparts, which could be advantageous. However, less is known about trait selection across populations along the invasion gradient in response to environmental factors, such as increasing drought caused by climate change. In this study, we investigated the impacts of drought on growth, regrowth, and various leaf traits in plants of different origin. Therefore, seeds of 18 populations of the perennial Tanacetum vulgare were collected along the invasion gradient (North America, invasive; West Europe, archaeophyte; East Europe, native) and grown in competition with the grass Poa pratensis under control or dry conditions in a common garden. Above-ground biomass was cut once and the regrowth was measured as an indicator for tolerance over a second growth period. Initially, drought had little effects on growth of T. vulgare, but after cutting, plants grew more vigorously. Against expectations, phenotypic plasticity was not higher in invasive populations, but even reduced in one trait, which may be attributable to ecological constraints imposed by multiple stress conditions. Trait responses reflected the range expansion and invasion gradient and were influenced by the latitudinal origin of populations. Populations of invaded ranges may be subject to faster and more extensive genetic mixing or had less time to undergo and reflect selective processes.

  3. Ecological context and metapopulation dynamics affect sex-ratio variation among dioecious plant populations

    PubMed Central

    Field, David L.; Pickup, Melinda; Barrett, Spencer C. H.

    2013-01-01

    Background and Aims Populations of dioecious flowering plants commonly exhibit heterogeneity in sex ratios and deviations from the equilibrium expectation of equal numbers of females and males. Yet the role of ecological and demographic factors in contributing towards biased sex ratios is currently not well understood. Methods Species-level studies from the literature were analysed to investigate ecological correlates of among-population sex-ratio variation and metapopulation models and empirical data were used to explore the influence of demography and non-equilibrium conditions on flowering sex ratios. Key Results The survey revealed significant among-population heterogeneity in sex ratios and this was related to the degree of sampling effort. For some species, sex-ratio bias was associated with the proportion of non-reproductive individuals, with greater male bias in populations with a lower proportion of individuals that were flowering. Male-biased ratios were also found at higher altitudes and latitudes, and in more xeric sites. Simulations and empirical data indicated that clonal species exhibited greater heterogeneity in sex ratios than non-clonal species as a result of their slower approach to equilibrium. The simulations also indicated the importance of interactions between reproductive mode and founder effects, with greater departures from equilibrium in clonal populations with fewer founding individuals. Conclusions The results indicate that sex-based differences in costs of reproduction and non-equilibrium conditions can each play important roles in affecting flowering sex ratios in populations of dioecious plants. PMID:23444124

  4. Plant rhizosphere effects on metal mobilization and transport. 1997 annual progress report

    SciTech Connect

    Fan, T.W.M.; Higashi, R.M.; Crowley, D.E.

    1997-10-01

    'During the funding period of 1996--1997, the authors explored the utility of multi-nuclear, two-dimensional nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) for a comprehensive analysis of barley root exudates collected under Fe sufficient and deficient conditions. As both structural and quantitative information was obtained directly from crude root exudates using this approach, no tedious sample fractionation was necessary, which will greatly facilitate future chemical characterization of root exudates in general. They found that the phytosiderophore mugineic acids (including 2{prime}-deoxymugineic acid, mugineic acid, and 3-epi-hydroxymugineic acid) were readily identified and quantified in crude exudate samples along with a number of amino and organic acids. The amount of mugineic acids excreted was correlated positively with the extent of Fe deficiency with 3-epi-hydroxymugineic acid being the most prominent component. The total Fe chelating capacity was also measured using the ferrozine assay and compared with the production of the mugineic acids. They were surprised to find that the mugineic acids may account for a part of the Fe chelating capacity, especially under mild and moderatley Fe deficient conditions. Lactate, alanine, y-aminobutyrate, malate, and glycinebetaine collectively may contribute to a significant fraction of the Fe chelating capacity. In light of the known stimulatory effect of alanine and citrate on metal availability to algae (Campell, 1995), the function of these low molecular weight metabolites as vehicles for Fe or metal uptake in general warrant further investigation. This work is now published in Analytical Biochemistry 251, 57-68 ( 1997). They then proceeded to apply the above approach to investigate the interaction of elevated cadmium (Cd) with Fe deficiency in gramineous plants. They have completed one each series of cadmium (Cd) treatments of barley and wheat seedlings under Fe

  5. Cytonuclear interactions affect adaptive traits of the annual plant Arabidopsis thaliana in the field

    PubMed Central

    Roux, Fabrice; Mary-Huard, Tristan; Barillot, Elise; Wenes, Estelle; Botran, Lucy; Durand, Stéphanie; Villoutreix, Romain; Martin-Magniette, Marie-Laure; Camilleri, Christine; Budar, Françoise

    2016-01-01

    Although the contribution of cytonuclear interactions to plant fitness variation is relatively well documented at the interspecific level, the prevalence of cytonuclear interactions at the intraspecific level remains poorly investigated. In this study, we set up a field experiment to explore the range of effects that cytonuclear interactions have on fitness-related traits in Arabidopsis thaliana. To do so, we created a unique series of 56 cytolines resulting from cytoplasmic substitutions among eight natural accessions reflecting within-species genetic diversity. An assessment of these cytolines and their parental lines scored for 28 adaptive whole-organism phenotypes showed that a large proportion of phenotypic traits (23 of 28) were affected by cytonuclear interactions. The effects of these interactions varied from slight but frequent across cytolines to strong in some specific parental pairs. Two parental pairs accounted for half of the significant pairwise interactions. In one parental pair, Ct-1/Sha, we observed symmetrical phenotypic responses between the two nuclear backgrounds when combined with specific cytoplasms, suggesting nuclear differentiation at loci involved in cytonuclear epistasis. In contrast, asymmetrical phenotypic responses were observed in another parental pair, Cvi-0/Sha. In the Cvi-0 nuclear background, fecundity and phenology-related traits were strongly affected by the Sha cytoplasm, leading to a modified reproductive strategy without penalizing total seed production. These results indicate that natural variation in cytoplasmic and nuclear genomes interact to shape integrative traits that contribute to adaptation, thereby suggesting that cytonuclear interactions can play a major role in the evolutionary dynamics of A. thaliana. PMID:26979961

  6. Rangeland plant response to elevated CO{sub 2}. Annual report, 1991

    SciTech Connect

    Owensby, C.E.; Coyne, P.I.; Ham, J.M.; Parton, W.; Rice, C.; Auen, L.M.; Adam, N.

    1991-12-31

    Effects of carbon dioxide enrichment on a tallgrass ecosystem were monitored during the 1990 growing season. The chambers, CO{sub 2} delivery system, and data acquisition and control system were in place and operational by 4 April 1990. CO{sub 2} fumigation and data acquisition began on that date. Nitrogen fertilizer as ammonium nitrate was applied at a rate of 45 kg ha {sup -1} on 1 April to the N-fertilized plots. The chambers were 4.5 m in diameter and 4 m in height to allow for destructive sampling for biomass accumulation, leaf area determination, and for grazing esophageally-fistulated sheep. The experimental site was located in pristine Tallgrass Prairie north of/and adjacent to the Kansas State University campus. Vegetation on the site was a mixture of C3 and C4 species and was dominated by big bluestem (Andropogon geradii vitman) and indiangrass (Sorghastrum nutans (L.) Nash). Subdominants included Kentucky bluegrass (Poa pratensis L.), sideoats grama (Bouteloua curtipendula (Michx.) Torr.), and tall dropseed (Sporobolus asper var. asper (Michx.) Kunth). Members of the sedge family made up 5-10% of the composition. Principal forbs included western ragweed (Ambrosia psilostachya DC.), Louisiana sagewort (Artemesia ludoviciana Nutt.), and mayflower scurfpea (Psoralea tenuiflora var. floribunda (Nutt.) Rydb.). Average peak biomass occurs in early August at 425 g m{sup -2} of which 35 g m{sup -2} is from forbs. The area was ideal for meeting the experimental objectives, in that the mixture of C3 and C4 plants would allow for assessment of competitive relationships among numerous species of both carbon fixation pathways.

  7. Comprehensive cooling water study annual report. Volume IX: waterfowl, Savannah River Plant

    SciTech Connect

    Gladden, J.B.; Lower, M.W.; Mackey, H.E.; Specht, W.L.; Wilde, E.W.

    1985-07-01

    The Savannah River Swamp System (SRSS) and Par Pond are used extensively by waterfowl, particularly during the fall and winter months when these areas provide habitat for migratory species. Twelve species of waterfowl are known to inhabit the SSRS, eleven are migratory species, and the wood duck is a year-round resident. Mallard ducks use the Four Mile Creek delta area of the SRSS during the winter if water levels are low, but use the Steel Creek delta if water levels are high during flooding from the Savannah River. Use of the thermal areas in Four Mile Creek and Pen Branch by waterfowl has been observed to decline in late February, while use of the Steel Creek swamp and Beaver Dam Creek area increases from March to May. Wood ducks appear to be dependent upon persistent and nonpersistent marsh and bottomland hardwood plant communities of the SRSS for foraging, but roost in scrub-shrub communities. The marsh and scrub-shrub communities are enhanced in the post-thermal Steel Creek delta relative to the river swamp areas, which explains the apparent importance of the Steel Creek delta area for these waterfowl. Portions of the Steel Creek delta which were previously excellent nesting habitat for wood ducks are providing poorer nesting habitat due to vegetational succession which has taken place since thermal discharges from L Reactor ended in 1968. Increased flow in the Steel Creek delta which would result from the restart of L Reactor may adversely affect waterfowl roosting and feed areas by increasing water depth and velocity and by altering vegetational patterns. 11 refs., 18 figs., 5 tabs.

  8. The Composition of Fluorescent Pseudomonad Populations Associated with Roots Is Influenced by Plant and Soil Type

    PubMed Central

    Latour, X.; Corberand, T.; Laguerre, G.; Allard, F.; Lemanceau, P.

    1996-01-01

    Populations of fluorescent pseudomonads isolated from an uncultivated soil and from the roots of two plant species were previously shown to differ (P. Lemanceau, T. Corberand, L. Gardan, X. Latour, G. Laguerre, J.-M. Boeufgras, and C. Alabouvette, Appl. Environ. Microbiol. 61:1004-1012, 1995). The diversities of fluorescent pseudomonads, from two uncultivated soils and from the roots of two plant species cultivated in these two soils, were compared. The phenotypic diversity of the bacterial isolates was characterized on the basis of biochemical and physiological tests and on the basis of their ability to utilize 147 different organic compounds. The genotypic diversity of the isolates was characterized on the basis of the types of 16S genes coding for rRNA (rDNA), their repetitive extragenic palindromic patterns by PCR, and plasmid profiles. Taxonomic identification of the isolates was achieved with both biochemical and physiological tests and by comparing their 16S rDNA types to those of reference and type strains of fluorescent Pseudomonas spp. Numerical analysis of phenotypic characteristics allowed the clustering of isolates that showed high levels of similarity. This analysis indicated that both soil type and host plant had an effect on the diversity of fluorescent pseudomonads. However, of the two factors studied, the soil was clearly the dominating one. Indeed, the populations associated with the roots of each plant species varied from one soil to the other. This variation could possibly be ascribed to the differences recorded between the phenotypically diverse populations of fluorescent pseudomonads from the two uncultivated soils. The plant selection was, at least partly, plant specific. It was not related to bacterial species and biovars or to the presence of plasmid DNA. The phenotypic clustering of isolates was well correlated with genotypic characterization by repetitive extragenic palindrome-PCR fingerprinting. PMID:16535355

  9. Evolutionary divergence and possible incipient speciation in post-glacial populations of a cosmopolitan aquatic plant.

    PubMed

    Nies, G; Reusch, T B H

    2005-01-01

    Habitat configuration is expected to have a major influence on genetic exchange and evolutionary divergence among populations. Aquatic organisms occur in two fundamentally different habitat types, the sea and freshwater lakes, making them excellent models to study the contrasting effects of continuity vs. isolation on genetic divergence. We compared the divergence in post-glacial populations of a cosmopolitan aquatic plant, the pondweed Potamogeton pectinatus that simultaneously occurs in freshwater lakes and coastal marine sites. Relative levels of gene flow were inferred in 12 lake and 14 Baltic Sea populations in northern Germany using nine highly polymorphic microsatellite markers developed for P. pectinatus. We found highly significant isolation-by-distance in both habitat types (P < 0.001). Genetic differentiation increased approximately 2.5-times faster among freshwater populations compared with those from the Baltic Sea. As different levels of genetic drift or population history cannot explain these differences, higher population connectivity in the sea relative to freshwater populations is the most likely source of contrasting evolutionary divergence. These findings are consistent with the notion that freshwater angiosperms are more conducive to allopatric speciation than their life-history counterparts in the sea, the relative species poor seagrasses. Surprisingly, population pairs from different habitat types revealed almost maximal genetic divergence expected for complete reproductive isolation, regardless of their respective geographical distance. Hence, the barrier to gene flow between lake and sea habitat types cannot be due to dispersal limitation. We may thus have identified a case of rapid incipient speciation in post-glacial populations of a widespread aquatic plant.

  10. A New Approach to the Quantification of Degree of Reciprocity in Distylous (sensu lato) Plant Populations

    PubMed Central

    Sanchez, Jose M.; Ferrero, Victoria; Navarro, Luis

    2008-01-01

    Background and Aims Although evolution of sexual polymorphism has been traditionally analysed using discrete characters, most of these polymorphisms are continuous. This is the case of heterostyly. Heterostyly is a floral polymorphism successfully used as a model to study the evolution of the sexual systems in plants. It involves the reciprocal positioning of anthers and stigmas in flowers of different plants within the same population. Studies of the functioning of heterostyly require the quantification of the degree of reciprocity between morphs of heterostylous species. Some reciprocity indices have been proposed previously, but they show significant limitations that need to be dealt with. This paper analyses these existing indices, and proposes a new index that aims to avoid their main problems (e.g. takes into account population variability and offers a single value per population). Methods The new index is based on the comparison of the position of every single sexual organ in the population with each and every organ of the opposite sex. To carry out all the calculations, a macro was programmed with MS®Visual Basic in MS® Excel. The behaviour of the index is tested using hypothetical data to simulate different situations of dimorphic populations; the index is also tested with some actual populations of different species of the genus Lithodora. Results and Conclusions The index of reciprocity proposed here is a sound alternative to previous indices: it compares stigma–stamen height gaps for all potential crosses in the population, it comprises stigma–stamen distance as well as dispersion, it is not skewed by the more frequent sex, and it can be meaningfully compared between populations and species. It has produced solid results for both hypothetical and natural populations. PMID:18621965

  11. Food preference and performance of the larvae of a specialist herbivore: variation among and within host-plant populations

    NASA Astrophysics Data System (ADS)

    Leimu, Roosa; Riipi, Marianna; Stærk, Dan

    2005-11-01

    Specialist herbivores are suggested to be unaffected by or attracted to the defense compounds of their host-plants, and can even prefer higher levels of certain chemicals. Abrostola asclepiadis is a specialist herbivore whose larvae feed on the leaves of Vincetoxicum hirundinaria, which contains toxic alkaloids and is unpalatable to most generalist herbivores. The food choice, leaf consumption and growth of A. asclepiadis larvae were studied to determine whether there is variation among and within host-plant populations in their suitability for this specialist herbivore. There was significant variation in food preference and leaf consumption among host-plant populations, but no differences were found in larval growth and feeding on different host-plant populations. A. asclepiadis larvae preferred host-plant populations with higher alkaloid concentrations, but did not consume more leaf material from plants originating from such populations in a no-choice experiment. There was also some variation in food preference of larvae among host-plant individuals belonging to the same population, suggesting that there was variability in leaf chemistry also within populations. Such variation in larval preference among host-plant genotypes and populations may create potential for coevolutionary dynamics in a spatial mosaic.

  12. Native and exotic plant species exhibit similar population dynamics during succession.

    PubMed

    Meiners, Scott J

    2007-05-01

    A growing body of literature has led to the debate in invasion biology whether exotic species perform within communities differently than native taxa due to inherent advantages. To address this issue, the population dynamics of native and exotic plant species were assessed from a 48-year record of permanent plot data from the Hutcheson Memorial Forest Center (New Jersey, USA) to determine rate of increase, lag time, maximum frequency, and the year of peak frequency. Overall, native and exotic species exhibited very similar population dynamics. Rates of increase and length of lag times were similar between native and exotic taxa but were strongly influenced by plant life form. Short-lived species were characterized by rapid population growth rates and short lag times. Growth rates decreased and lag times increased with species longevity. Overall, correlations between population metrics were the same in native and exotic taxa, suggesting similar trade-offs in life history patterns. The one difference observed was that, in native species, peak frequency was negatively associated with the year of peak frequency (i.e., early-successional species tended to become more abundant), while there was no relationship in exotic species. These analyses show that exotic species behave in essentially the same way as native taxa within dynamic communities. This suggests that abundant native and exotic plant species are exploiting the same range of ecological strategies resulting in similar roles within communities.

  13. Nitrogen soil emissions and belowground plant processes in Mediterranean annual pastures are altered by ozone exposure and N-inputs

    NASA Astrophysics Data System (ADS)

    Sánchez-Martín, L.; Bermejo-Bermejo, V.; García-Torres, L.; Alonso, R.; de la Cruz, A.; Calvete-Sogo, H.; Vallejo, A.

    2017-09-01

    Increasing tropospheric ozone (O3) and atmospheric nitrogen (N) deposition alter the structure and composition of pastures. These changes could affect N and C compounds in the soil that in turn can influence soil microbial activity and processes involved in the emission of N oxides, methane (CH4) and carbon dioxide (CO2), but these effects have been scarcely studied. Through an open top chamber (OTC) field experiment, the combined effects of both pollutants on soil gas emissions from an annual experimental Mediterranean community were assessed. Four O3 treatments and three different N input levels were considered. Fluxes of nitric (NO) and nitrous (N2O) oxide, CH4 and CO2 were analysed as well as soil mineral N and dissolved organic carbon. Belowground plant parameters like root biomass and root C and N content were also sampled. Ozone strongly increased soil N2O emissions, doubling the cumulative emission through the growing cycle in the highest O3 treatment, while N-inputs enhanced more slightly NO; CH4 and CO2 where not affected. Both N-gases had a clear seasonality, peaking at the start and at the end of the season when pasture physiological activity is minimal; thus, higher microorganism activity occurred when pasture had a low nutrient demand. The O3-induced peak of N2O under low N availability at the end of the growing season was counterbalanced by the high N inputs. These effects were related to the O3 x N significant interaction found for the root-N content in the grass and the enhanced senescence of the community. Results indicate the importance of the belowground processes, where competition between plants and microorganisms for the available soil N is a key factor, for understanding the ecosystem responses to O3 and N.

  14. 2005 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

    SciTech Connect

    Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P.; Allwardt, Craig H.

    2008-08-12

    Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2005 sampling year monitoring results from individual segments.

  15. 2006 Annual Synthesis Report, Pallid Sturgeon Population Assessment Program and Associated Fish Community Monitoring for the Missouri River

    SciTech Connect

    Oldenburg, Eric W.; Hanrahan, Timothy P.; Harnish, Ryan A.; Bellgraph, Brian J.; Duncan, Joanne P.; Allwardt, Craig H.

    2008-08-12

    Pallid sturgeon, Scaphirhynchus albus, have declined throughout the Missouri River since dam construction and inception of the Bank Stabilization and Navigation Project in 1912. Their decline likely is due to the loss and degradation of their natural habitat as a result of changes in the river’s structure and function, as well as the pallid sturgeon’s inability to adapt to these changes. The U. S. Army Corps of Engineers has been working with state and federal agencies to develop and conduct a Pallid Sturgeon Monitoring and Assessment Program (Program), with the goal of recovering pallid sturgeon populations. The Program has organized the monitoring and assessment efforts into distinct geographic segments, with state and federal resource management agencies possessing primary responsibility for one or more segment. To date, the results from annual monitoring have been reported for individual Program segments. However, monitoring results have not been summarized or evaluated for larger spatial scales, encompassing more than one Program segment. This report describes a summary conducted by the Pacific Northwest National Laboratory (PNNL) that synthesizes the 2006 sampling year monitoring results from individual segments.

  16. Starting new populations of longleaf pine ground-layer plants in the Outer Coastal Plain of South Carolina, USA.

    SciTech Connect

    Glitzenstein, J.S.; Streng, Donna R.; Wade, D.D.; Brubaker, J.

    2001-01-01

    Abstract: Southeastern United States habitats dominated by longleaf pine (Pinus palustris Miller) and associated plant species have declined dangerously. Conservation of rare and common plants of longleaf pine habitats may be aided by starting new populations in the field. We review methods for initiating plant populations and integrate information from our studies of rare and common longleaf pine ground-layer plants of the outer South Carolina Coastal Plain. In our experience it is possible to start new populations of most longleaf pine ground-layer plants, including rare species if (1) seeds are collected from frequently burned sites with reasonably large populations of desired species; (2) appropriate media are used for seedling propagation; (3) outplanting of nursery grown seedlings or direct seeding is done during periods of sufficient soil moisture; and (4) introduction sites properly match