Learned Vocal Variation Is Associated with Abrupt Cryptic Genetic Change in a Parrot Species Complex

PubMed Central

Ribot, Raoul F. H.; Buchanan, Katherine L.; Endler, John A.; Joseph, Leo; Bennett, Andrew T. D.; Berg, Mathew L.

2012-01-01

Contact zones between subspecies or closely related species offer valuable insights into speciation processes. A typical feature of such zones is the presence of clinal variation in multiple traits. The nature of these traits and the concordance among clines are expected to influence whether and how quickly speciation will proceed. Learned signals, such as vocalizations in species having vocal learning (e.g. humans, many birds, bats and cetaceans), can exhibit rapid change and may accelerate reproductive isolation between populations. Therefore, particularly strong concordance among clines in learned signals and population genetic structure may be expected, even among continuous populations in the early stages of speciation. However, empirical evidence for this pattern is often limited because differences in vocalisations between populations are driven by habitat differences or have evolved in allopatry. We tested for this pattern in a unique system where we may be able to separate effects of habitat and evolutionary history. We studied geographic variation in the vocalizations of the crimson rosella (Platycercus elegans) parrot species complex. Parrots are well known for their life-long vocal learning and cognitive abilities. We analysed contact calls across a ca 1300 km transect encompassing populations that differed in neutral genetic markers and plumage colour. We found steep clinal changes in two acoustic variables (fundamental frequency and peak frequency position). The positions of the two clines in vocal traits were concordant with a steep cline in microsatellite-based genetic variation, but were discordant with the steep clines in mtDNA, plumage and habitat. Our study provides new evidence that vocal variation, in a species with vocal learning, can coincide with areas of restricted gene flow across geographically continuous populations. Our results suggest that traits that evolve culturally can be strongly associated with reduced gene flow between populations, and therefore may promote speciation, even in the absence of other barriers. PMID:23227179

Phylogeography of Asian wild rice, Oryza rufipogon: a genome-wide view.

PubMed

Huang, Pu; Molina, Jeanmaire; Flowers, Jonathan M; Rubinstein, Samara; Jackson, Scott A; Purugganan, Michael D; Schaal, Barbara A

2012-09-01

Asian wild rice (Oryza rufipogon) that ranges widely across the eastern and southern part of Asia is recognized as the direct ancestor of cultivated Asian rice (O. sativa). Studies of the geographic structure of O. rufipogon, based on chloroplast and low-copy nuclear markers, reveal a possible phylogeographic signal of subdivision in O. rufipogon. However, this signal of geographic differentiation is not consistently observed among different markers and studies, with often conflicting results. To more precisely characterize the phylogeography of O. rufipogon populations, a genome-wide survey of unlinked markers, intensively sampled from across the entire range of O. rufipogon is critical. In this study, we surveyed sequence variation at 42 genome-wide sequence tagged sites (STS) in 108 O. rufipogon accessions from throughout the native range of the species. Using Bayesian clustering, principal component analysis and amova, we conclude that there are two genetically distinct O. rufipogon groups, Ruf-I and Ruf-II. The two groups exhibit a clinal variation pattern generally from north-east to south-west. Different from many earlier studies, Ruf-I, which is found mainly in China and the Indochinese Peninsula, shows genetic similarity with one major cultivated rice variety, O. satvia indica, whereas Ruf-II, mainly from South Asia and the Indochinese Peninsula, is not found to be closely related to cultivated rice varieties. The other major cultivated rice variety, O. sativa japonica, is not found to be similar to either O. rufipogon groups. Our results support the hypothesis of a single origin of the domesticated O. sativa in China. The possible role of palaeoclimate, introgression and migration-drift balance in creating this clinal variation pattern is also discussed. © 2012 Blackwell Publishing Ltd.

Rapid movement and instability of an invasive hybrid swarm

USGS Publications Warehouse

Glotzbecker, Gregory J.; Walters, David; Blum, Michael J.

2016-01-01

Unstable hybrid swarms that arise following the introduction of non-native species can overwhelm native congeners, yet the stability of invasive hybrid swarms has not been well documented over time. Here we examine genetic variation and clinal stability across a recently formed hybrid swarm involving native blacktail shiner (Cyprinella venusta) and non-native red shiner (C. lutrensis) in the Upper Coosa River basin, which is widely considered to be a global hotspot of aquatic biodiversity. Examination of phenotypic, multilocus genotypic, and mitochondrial haplotype variability between 2005 and 2011 revealed that the proportion of hybrids has increased over time, with more than a third of all sampled individuals exhibiting admixture in the final year of sampling. Comparisons of clines over time indicated that the hybrid swarm has been rapidly progressing upstream, but at a declining and slower pace than rates estimated from historical collection records. Clinal comparisons also showed that the hybrid swarm has been expanding and contracting over time. Additionally, we documented the presence of red shiner and hybrids farther downstream than prior studies have detected, which suggests that congeners in the Coosa River basin, including all remaining populations of the threatened blue shiner (Cyprinella caerulea), are at greater risk than previously thought.

Natural Genetic Variation and Candidate Genes for Morphological Traits in Drosophila melanogaster

PubMed Central

Carreira, Valeria Paula; Mensch, Julián; Hasson, Esteban; Fanara, Juan José

2016-01-01

Body size is a complex character associated to several fitness related traits that vary within and between species as a consequence of environmental and genetic factors. Latitudinal and altitudinal clines for different morphological traits have been described in several species of Drosophila and previous work identified genomic regions associated with such variation in D. melanogaster. However, the genetic factors that orchestrate morphological variation have been barely studied. Here, our main objective was to investigate genetic variation for different morphological traits associated to the second chromosome in natural populations of D. melanogaster along latitudinal and altitudinal gradients in Argentina. Our results revealed weak clinal signals and a strong population effect on morphological variation. Moreover, most pairwise comparisons between populations were significant. Our study also showed important within-population genetic variation, which must be associated to the second chromosome, as the lines are otherwise genetically identical. Next, we examined the contribution of different candidate genes to natural variation for these traits. We performed quantitative complementation tests using a battery of lines bearing mutated alleles at candidate genes located in the second chromosome and six second chromosome substitution lines derived from natural populations which exhibited divergent phenotypes. Results of complementation tests revealed that natural variation at all candidate genes studied, invected, Fasciclin 3, toucan, Reticulon-like1, jing and CG14478, affects the studied characters, suggesting that they are Quantitative Trait Genes for morphological traits. Finally, the phenotypic patterns observed suggest that different alleles of each gene might contribute to natural variation for morphological traits. However, non-additive effects cannot be ruled out, as wild-derived strains differ at myriads of second chromosome loci that may interact epistatically with mutant alleles. PMID:27459710

Clinal variation at microsatellite loci reveals historical secondary intergradation between glacial races of Coregonus artedi (Teleostei: Coregoninae).

PubMed

Turgeon, J; Bernatchez, L

2001-11-11

Classical models of the spatial structure of population genetics rely on the assumption of migration-drift equilibrium, which is seldom met in natural populations having only recently colonized their current range (e.g., postglacial). Population structure then depicts historical events, and counfounding effects due to recent secondary contact between recently differentiated lineages can further counfound analyses of association between geographic and genetic distances. Mitochondrial polymorphisms have revealed the existence of two closely related lineages of the lake cisco, Coregonus artedi, whose significantly different but overlaping geographical distributions provided a weak signal of past range fragmentation blurred by putative subsequent extensive secondary contacts. In this study, we analyzed geographical patterns of genetic variation at seven microsatellite loci among 22 populations of lake cisco located along the axis of an area covered by proglacial lakes 12,000-8,000 years ago in North America. The results clearly confirmed the existence of two genetically distinct races characterized by different sets of microsatellite alleles whose frequencies varied clinally across some 3000 km. Equilibrium and nonequilibrium analyses of isolation by distance revealed historical signal of gene flow resulting from the nearly complete admixture of these races following neutral secondary contacts in their historical habitat and indicated that the colonization process occurred by a stepwise expansion of an eastern (Atlantic) race into a previously established Mississippian race. This historical signal of equilibrium contrasted with the current migration-drift disequilibrium within major extant watersheds and was apparently maintained by high effective population sizes and low migration regimes.

Geographic variation in responses of European yellow dung flies to thermal stress.

PubMed

Bauerfeind, Stephanie S; Sørensen, Jesper G; Loeschcke, Volker; Berger, David; Broder, E Dale; Geiger, Madeleine; Ferrari, Manuela; Blanckenhorn, Wolf U

2018-04-01

Climatic conditions can be very heterogeneous even over small geographic scales, and are believed to be major determinants of the abundance and distribution of species and populations. Organisms are expected to evolve in response to the frequency and magnitude of local thermal extremes, resulting in local adaptation. Using replicate yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae) populations from cold (northern Europe) and warm climates (southern Europe), we compared 1) responses to short-term heat and cold shocks in both sexes, 2) heat shock protein (Hsp70) expression in adults and eggs, and 3) female reproductive traits when facing short-term heat stress during egg maturation. Contrary to expectations, thermal traits showed minor geographic differentiation, with weak evidence for greater heat resistance of southern flies but no differentiation in cold resistance. Hsp70 protein expression was little affected by heat stress, indicating systemic rather than induced regulation of the heat stress response, possibly related to this fly group's preference for cold climes. In contrast, sex differences were pronounced: males (which are larger) endured hot temperatures longer, while females featured higher Hsp70 expression. Heat stress negatively affected various female reproductive traits, reducing first clutch size, overall reproductive investment, egg lipid content, and subsequent larval hatching. These responses varied little across latitude but somewhat among populations in terms of egg size, protein content, and larval hatching success. Several reproductive parameters, but not Hsp70 expression, exhibited heritable variation among full-sib families. Rather than large-scale clinal geographic variation, our study suggests some local geographic population differentiation in the ability of yellow dung flies to buffer the impact of heat stress on reproductive performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mapping human genetic diversity in Asia.

PubMed

Abdulla, Mahmood Ameen; Ahmed, Ikhlak; Assawamakin, Anunchai; Bhak, Jong; Brahmachari, Samir K; Calacal, Gayvelline C; Chaurasia, Amit; Chen, Chien-Hsiun; Chen, Jieming; Chen, Yuan-Tsong; Chu, Jiayou; Cutiongco-de la Paz, Eva Maria C; De Ungria, Maria Corazon A; Delfin, Frederick C; Edo, Juli; Fuchareon, Suthat; Ghang, Ho; Gojobori, Takashi; Han, Junsong; Ho, Sheng-Feng; Hoh, Boon Peng; Huang, Wei; Inoko, Hidetoshi; Jha, Pankaj; Jinam, Timothy A; Jin, Li; Jung, Jongsun; Kangwanpong, Daoroong; Kampuansai, Jatupol; Kennedy, Giulia C; Khurana, Preeti; Kim, Hyung-Lae; Kim, Kwangjoong; Kim, Sangsoo; Kim, Woo-Yeon; Kimm, Kuchan; Kimura, Ryosuke; Koike, Tomohiro; Kulawonganunchai, Supasak; Kumar, Vikrant; Lai, Poh San; Lee, Jong-Young; Lee, Sunghoon; Liu, Edison T; Majumder, Partha P; Mandapati, Kiran Kumar; Marzuki, Sangkot; Mitchell, Wayne; Mukerji, Mitali; Naritomi, Kenji; Ngamphiw, Chumpol; Niikawa, Norio; Nishida, Nao; Oh, Bermseok; Oh, Sangho; Ohashi, Jun; Oka, Akira; Ong, Rick; Padilla, Carmencita D; Palittapongarnpim, Prasit; Perdigon, Henry B; Phipps, Maude Elvira; Png, Eileen; Sakaki, Yoshiyuki; Salvador, Jazelyn M; Sandraling, Yuliana; Scaria, Vinod; Seielstad, Mark; Sidek, Mohd Ros; Sinha, Amit; Srikummool, Metawee; Sudoyo, Herawati; Sugano, Sumio; Suryadi, Helena; Suzuki, Yoshiyuki; Tabbada, Kristina A; Tan, Adrian; Tokunaga, Katsushi; Tongsima, Sissades; Villamor, Lilian P; Wang, Eric; Wang, Ying; Wang, Haifeng; Wu, Jer-Yuarn; Xiao, Huasheng; Xu, Shuhua; Yang, Jin Ok; Shugart, Yin Yao; Yoo, Hyang-Sook; Yuan, Wentao; Zhao, Guoping; Zilfalil, Bin Alwi

2009-12-11

Asia harbors substantial cultural and linguistic diversity, but the geographic structure of genetic variation across the continent remains enigmatic. Here we report a large-scale survey of autosomal variation from a broad geographic sample of Asian human populations. Our results show that genetic ancestry is strongly correlated with linguistic affiliations as well as geography. Most populations show relatedness within ethnic/linguistic groups, despite prevalent gene flow among populations. More than 90% of East Asian (EA) haplotypes could be found in either Southeast Asian (SEA) or Central-South Asian (CSA) populations and show clinal structure with haplotype diversity decreasing from south to north. Furthermore, 50% of EA haplotypes were found in SEA only and 5% were found in CSA only, indicating that SEA was a major geographic source of EA populations.

A Preliminary Study of Genetic Variation in Populations of Monstera adansonii var. klotzschiana (Araceae) from North-East Brazil, Estimated with AFLP Molecular Markers

PubMed Central

Andrade, I. M.; Mayo, S. J.; van den Berg, C.; Fay, M. F.; Chester, M.; Lexer, C.; Kirkup, D.

2007-01-01

Background and Aims This study sought genetic evidence of long-term isolation in populations of Monstera adansonii var. klotzschiana (Araceae), a herbaceous, probably outbreeding, humid forest hemi-epiphyte, in the brejo forests of Ceará (north-east Brazil), and clarification of their relationships with populations in Amazonia and the Atlantic forest of Brazil. Methods Within-population genetic diversity and between-population dissimilarity were estimated using AFLP molecular markers in 75 individuals from eight populations located in Ceará, the Brazilian Atlantic Forest and Amazonia. Key Results The populations showed a clinal pattern of weak genetic differentiation over a large geographical region (FST = 0·1896). A strong correlation between genetic and geographical distance (Mantel test: r = 0·6903, P = 0·002) suggests a historical pattern of isolation by distance. Genetic structure analysis revealed at least two distinct gene pools in the data. The two isolated Ceará populations are significantly different from each other (pairwise ΦPT = 0·137, P = 0·003) and as diverse (Nei's gene diversity, average He = 0·1832, 0·1706) as those in the Atlantic and Amazon forest regions. The population in southern Brazil is less diverse (Nei's gene diversity, average He = 0·127) than the rest. The Ceará populations are related to those of the Atlantic forest rather than those from Amazonia (AMOVA, among-groups variation = 11·95 %, P = 0·037). Conclusions The gene pools detected within an overall pattern of clinal variation suggest distinct episodes of gene flow, possibly correlated with past humid forest expansions. The Ceará populations show no evidence of erosion of genetic diversity, although this was expected because of their isolation. Their genetic differentiation and relatively high diversity reinforce the importance of conserving the endangered brejo forests. PMID:17823112

Mitochondrial phylogeography, subspecific taxonomy, and conservation genetics of sandhill cranes (Grus canadensis; Aves: Gruidae)

USGS Publications Warehouse

Rhymer, J.M.; Fain, M.G.; Austin, J.E.; Johnson, D.H.; Krajewski, C.

2001-01-01

Six subspecies of sandhill cranes (Grus canadensis) have been denoted based on perceived morphological and/or breeding locality differences among them. Three subspecies are migratory, breeding from the high arctic in North America and Siberia (lesser sandhill, G. c. canadensis), south through central Canada (Canadian sandhill, G. c. rowani) and into the northern United States (greater sandhill, G. c. tabida). A review of sandhill crane taxonomy indicates that the size variation, on the basis of which these subspecies were named, may be clinal and not diagnostic. The other three subspecies, all listed as endangered or threatened, are non-migratory, resident in Florida (G. c. pratensis), Mississippi (G. c. pulla), and Cuba (G. c. nesiotes). We used analysis of mitochondrial DNA control region (CR) sequences to determine whether haplotypes representing current subspecies show any genetic cohesion or are more consistent with a pattern of clinal variation in morphology. CR sequences indicate that only two highly divergent (5.3%) lineages of sandhill cranes occur in North America: one lineage composed only of arctic-nesting G. c. canadensis, the other of the remaining North American subspecies (we lack data on the Cuban population). The deep split between lineages is consistent with an estimated isolation of approximately 1.5 Mya (mid-Pleistocene), while the distribution of mutational changes within lineages is consistent with an hypothesis of rapid, post-Pleistocene population expansions. No other phylogeographic structuring is concordant with subspecific boundaries, however, analysis of molecular variance indicates that there is significant population genetic differentiation among all subspecies except G. c. tabida and G. c. rowani, which are indistinguishable. We suggest that recognition of the recently named G. c. rowani be abandoned.

Variations in chemical sexual signals of Psammodromus algirus lizards along an elevation gradient may reflect altitudinal variation in microclimatic conditions

NASA Astrophysics Data System (ADS)

Martín, José; Javier Zamora-Camacho, Francisco; Reguera, Senda; López, Pilar; Moreno-Rueda, Gregorio

2017-04-01

Chemical signals used in intraspecific communication are expected to evolve or to show phenotipic plasticity to maximize efficacy in the climatic conditions of a given environment. Elevational environmental gradients in mountains provide a good opportunity to test this hypothesis by examining variation in characteristics of signals in species found across different elevations with different climatic conditions. We analyzed by gas chromatography-mass spectrometry (GC-MS) the lipophilic fraction of the femoral gland secretions of male lizards Psammodromus algirus (Fam. Lacertidae) from six localities located along a 2200 m elevational gradient at Sierra Nevada Mountains (SE Spain). There was elevational clinal variation in climatic variables, number of femoral pores and in the relative proportions of some classes of compounds (i.e., ethyl esters of fatty acids, waxy esters, and aldehydes) but not others. We discuss how this variation would result in different physicochemical properties of the entire femoral secretion, which might help optimize the efficacy of chemical signals under the particular microclimatic conditions at each elevation.

Variations in chemical sexual signals of Psammodromus algirus lizards along an elevation gradient may reflect altitudinal variation in microclimatic conditions.

PubMed

Martín, José; Javier Zamora-Camacho, Francisco; Reguera, Senda; López, Pilar; Moreno-Rueda, Gregorio

2017-04-01

Chemical signals used in intraspecific communication are expected to evolve or to show phenotipic plasticity to maximize efficacy in the climatic conditions of a given environment. Elevational environmental gradients in mountains provide a good opportunity to test this hypothesis by examining variation in characteristics of signals in species found across different elevations with different climatic conditions. We analyzed by gas chromatography-mass spectrometry (GC-MS) the lipophilic fraction of the femoral gland secretions of male lizards Psammodromus algirus (Fam. Lacertidae) from six localities located along a 2200 m elevational gradient at Sierra Nevada Mountains (SE Spain). There was elevational clinal variation in climatic variables, number of femoral pores and in the relative proportions of some classes of compounds (i.e., ethyl esters of fatty acids, waxy esters, and aldehydes) but not others. We discuss how this variation would result in different physicochemical properties of the entire femoral secretion, which might help optimize the efficacy of chemical signals under the particular microclimatic conditions at each elevation.

Taxonomy of the genus Lycalopex (Carnivora: Canidae) in Argentina

USGS Publications Warehouse

Zunino, G.E.; Vaccaro, O.B.; Canevari, M.; Gardner, A.L.

1995-01-01

Previously treated as species of Pseudalopex, Argentine members of the genus Lycalopex (L. griseus, L. gymnocercus, and L. culpaeus) are examined to clarify the taxonomic status of each named form. Principal components analyses of 26 cranial measurements of 151 adult specimens and 11 pelage characters of 111 specimens, clearly distinguish L. culpaeus from the other two taxa. Lycalopex griseus and L. gymnocercus show clinal variation in cranial measurements and pelage characters. Qualitative cranial characters, used as diagnostic for L. griseus and L. gymnocercus, revealed great nongeographic variation. We conclude that L. griseus and L. gymnocercus are conspecific, and should be known as L. gymnocercus. Therefore, we recognize only two species of the genus Lycalopex (L. culpaeus and L. gymnocercus) in Argentina. We also use this opportunity to review synonymies of the recognized species of Lycalopex.

Local Populations of Arabidopsis thaliana Show Clear Relationship between Photoperiodic Sensitivity of Flowering Time and Altitude

PubMed Central

Lewandowska-Sabat, Anna M.; Fjellheim, Siri; Olsen, Jorunn E.; Rognli, Odd A.

2017-01-01

Adaptation of plants to local conditions that vary substantially within their geographic range is essential for seasonal timing of flowering, a major determinant of plant reproductive success. This study investigates photoperiodic responses in natural populations of Arabidopsis thaliana from high northern latitudes and their significance for local adaptation. Thirty lineages from ten local A. thaliana populations, representing different locations across an altitudinal gradient (2–850 m a.s.l.) in Norway, were grown under uniform controlled conditions, and used to screen for responses to five different photoperiods. We studied relationships between variation in photoperiodic sensitivity of flowering time, altitude, and climatic factors associated with the sites of origin. We found that variation in response to photoperiod is significantly correlated with altitude and climatic variables associated with the sites of origin of the populations. Populations originating from lower altitudes showed stronger photoperiodic sensitivity than populations from higher altitudes. Our results indicate that the altitudinal climatic gradient generates clinal variation in adaptive traits in A. thaliana. PMID:28659966

Physiological constraints on organismal response to global warming: Mechanistic insights from clinally varying populations and implications for assessing endangerment.

PubMed

Bernardo, Joseph; Spotila, James R

2006-03-22

Recent syntheses indicate that global warming affects diverse biological processes, but also highlight the potential for some species to adapt behaviourally or evolutionarily to rapid climate change. Far less attention has addressed the alternative, that organisms lacking this ability may face extinction, a fate projected to befall one-quarter of global biodiversity. This conclusion is controversial, in part because there exist few mechanistic studies that show how climate change could precipitate extinction. We provide a concrete, mechanistic example of warming as a stressor of organisms that are closely adapted to cool climates from a comparative analysis of organismal tolerance among clinally varying populations along a natural thermal gradient. We found that two montane salamanders exhibit significant metabolic depression at temperatures within the natural thermal range experienced by low and middle elevation populations. Moreover, the magnitude of depression was inversely related to native elevation, suggesting that low elevation populations are already living near the limit of their physiological tolerances. If this finding generally applies to other montane specialists, the prognosis for biodiversity loss in typically diverse montane systems is sobering. We propose that indices of warming-induced stress tolerance may provide a critical new tool for quantitative assessments of endangerment due to anthropogenic climate change across diverse species.

Geographical variation of St. Lucia Parrot flight vocalizations

USGS Publications Warehouse

Kleeman, Patrick M.; Gilardi, James D.

2005-01-01

Parrots are vocal learners and many species of parrots are capable of learning new calls, even as adults. This capability gives parrots the potential to develop communication systems that can vary dramatically over space. St. Lucia Parrot (Amazona versicolor) flight vocalizations were examined for geographic variation between four different sites on the island of St. Lucia. Spectrographic cross-correlation analysis of a commonly used flight vocalization, the p-chow call, demonstrated quantitative differences between sites. Additionally, the similarity of p-chows decreased as the distance between sites increased. Flight call repertoires also differed among sites; parrots at the Des Bottes and Quilesse sites each used one flight call unique to those sites, while parrots at the Barre de L'Isle site used a flight call that Quilesse parrots gave only while perched. It is unclear whether the vocal variation changed clinally with distance, or whether there were discrete dialect boundaries as in a congener, the Yellow-naped Parrot (Amazona auropalliata, Wright 1996). The geographical scale over which the St. Lucia Parrot's vocal variation occurred was dramatically smaller than that of the Yellow-naped Parrot. Similar patterns of fine-scale vocal variation may be more widespread among other parrot species in the Caribbean than previously documented.

Lack of genetic structure among ecologically adapted populations of an Australian rainforest Drosophila species as indicated by microsatellite markers and mitochondrial DNA sequences.

PubMed

Schiffer, Michele; Kennington, W J; Hoffmann, A A; Blacket, M J

2007-04-01

Although fragmented rainforest environments represent hotspots for invertebrate biodiversity, few genetic studies have been conducted on rainforest invertebrates. Thus, it is not known if invertebrate species in rainforests are highly genetically fragmented, with the potential for populations to show divergent selection responses, or if there are low levels of gene flow sufficient to maintain genetic homogeneity among fragmented populations. Here we use microsatellite markers and DNA sequences from the mitochondrial ND5 locus to investigate genetic differences among Drosophila birchii populations from tropical rainforests in Queensland, Australia. As found in a previous study, mitochondrial DNA diversity was low with no evidence for population differentiation among rainforest fragments. The pattern of mitochondrial haplotype variation was consistent with D. birchii having undergone substantial past population growth. Levels of nuclear genetic variation were high in all populations while F(ST) values were very low, even for flies from geographically isolated areas of rainforest. No significant differentiation was observed between populations on either side of the Burdekin Gap (a long-term dry corridor), although there was evidence for higher gene diversity in low-latitude populations. Spatial autocorrelation coefficients were low and did not differ significantly from random, except for one locus which revealed a clinal-like pattern. Comparisons of microsatellite differentiation contrasted with previously established clinal patterns in quantitative traits in D. birchii, and indicate that the patterns in quantitative traits are likely to be due to selection. These results suggest moderate gene flow in D. birchii over large distances. Limited population structure in this species appears to be due to recent range expansions or cycles of local extinctions followed by recolonizations/expansions. Nevertheless, patterns of local adaptation have developed in D. birchii that may result in populations showing different selection responses when faced with environmental change.

Convergent and divergent patterns of morphological differentiation provide more evidence for reproductive character displacement in a wood cricket Gryllus fultoni (Orthoptera: Gryllidae)

PubMed Central

Jang, Yikweon; Won, Yong-Jin; Choe, Jae Chun

2009-01-01

Background In ecological character displacement, traits involved in reproductive isolation may not evolve in arbitrary directions when changes in these traits are by-products of adaptation to an ecological niche. In reproductive character displacement, however, selection acts directly on reproductive characters to enhance the degree of reproductive isolation between sympatric populations. Thus, the direction of change in reproductive characters may be arbitrary in relation to changes in other morphological characters. We characterized both tegminal characters and characters indicative of body size in sympatric and allopatric populations of Gryllus fultoni, a species displaying character displacement in its calling song characters in areas of sympatry with G. vernalis populations, to infer the nature and direction of selection acting on reproductive and morphological characters in sympatry. Results Except for mirror area, the number of teeth in a file, and ovipositor length of G. fultoni, all male and female morphological characters in G. fultoni and G. vernalis exhibited a uniform tendency to decrease in size with increasing latitude. There was no significant variation in female morphological characters between sympatric and allopatric G. fultoni populations. However, males of sympatric and allopatric G. fultoni populations significantly differed in head width, hind femur length, and mirror area even after controlling for clinal factors. Head width and hind femur length of G. fultoni were more similar to those of G. vernalis in sympatric populations than in allopatric populations, resulting in morphological convergence of G. fultoni and G. vernalis in sympatry. However, the mirror area of G. fultoni displayed the divergent pattern in relation to the sympatric G. vernalis populations. Conclusion Divergence-enhancing selection may be acting on mirror area as well as calling song characters, whereas local adaptation or clinal effects may explain variation in other morphological characters in sympatric populations of G. fultoni. This study also suggests that structures and behaviors that directly enhance reproductive isolation may evolve together, independently of other morphological traits. PMID:19183503

Convergent and divergent patterns of morphological differentiation provide more evidence for reproductive character displacement in a wood cricket Gryllus fultoni (Orthoptera: Gryllidae).

PubMed

Jang, Yikweon; Won, Yong-Jin; Choe, Jae Chun

2009-02-01

In ecological character displacement, traits involved in reproductive isolation may not evolve in arbitrary directions when changes in these traits are by-products of adaptation to an ecological niche. In reproductive character displacement, however, selection acts directly on reproductive characters to enhance the degree of reproductive isolation between sympatric populations. Thus, the direction of change in reproductive characters may be arbitrary in relation to changes in other morphological characters. We characterized both tegminal characters and characters indicative of body size in sympatric and allopatric populations of Gryllus fultoni, a species displaying character displacement in its calling song characters in areas of sympatry with G. vernalis populations, to infer the nature and direction of selection acting on reproductive and morphological characters in sympatry. Except for mirror area, the number of teeth in a file, and ovipositor length of G. fultoni, all male and female morphological characters in G. fultoni and G. vernalis exhibited a uniform tendency to decrease in size with increasing latitude. There was no significant variation in female morphological characters between sympatric and allopatric G. fultoni populations. However, males of sympatric and allopatric G. fultoni populations significantly differed in head width, hind femur length, and mirror area even after controlling for clinal factors. Head width and hind femur length of G. fultoni were more similar to those of G. vernalis in sympatric populations than in allopatric populations, resulting in morphological convergence of G. fultoni and G. vernalis in sympatry. However, the mirror area of G. fultoni displayed the divergent pattern in relation to the sympatric G. vernalis populations. Divergence-enhancing selection may be acting on mirror area as well as calling song characters, whereas local adaptation or clinal effects may explain variation in other morphological characters in sympatric populations of G. fultoni. This study also suggests that structures and behaviors that directly enhance reproductive isolation may evolve together, independently of other morphological traits.

The aggressive call of Dendropsophus cruzi (Pombal Bastos, 1998) (Anura; Hylidae) in Central Brazil.

PubMed

Andreani, Tainà Lucas; Oliveira, Seixas Rezende; Guerra, VinÍcius; Bastos, RogÉrio Pereira; De Morais, Alessandro Ribeiro

2018-02-13

Dendropsophus cruzi (Pombal Bastos, 1998) is a small hylid (male snout-to-vent length = 16.3-19.4 mm; female SVL = 21.3-25.0 mm) that is allocated in the D. microcephalus group (Faivovich et al. 2005). It is commonly found in Open and forested areas from Central Brazil to Provincia Velasco, Departamento de Santa Cruz, Bolivia (Frost 2017; Tessarolo et al. 2016). Pombal Bastos (1998) described the advertisement call of D. cruzi as a single pulsed note. Posteriorly, studies uncovered relationships between dominant frequency variation in the advertisement calls of D. cruzi and variation in the SVL and mass of males (Bastos et al. 2003), as well as the existence of a clinal geographic pattern in the variation of acoustic parameters of these calls (Tessarolo et al. 2016). However, the acoustic communication in anurans is usually mediated by more than one vocalization type (Toledo et al. 2015). Due the importance of call types in the social context of anurans (e.g., Reichert 2011; Forti et al. 2017), we expand the vocal repertoire of D. cruzi by describing its aggressive call.

Largely flat latitudinal life history clines in the dung fly Sepsis fulgens across Europe (Diptera: Sepsidae).

PubMed

Roy, Jeannine; Blanckenhorn, Wolf U; Rohner, Patrick T

2018-05-17

Clinal variation in body size and related life history traits is common and has stimulated the postulation of several eco-geographical rules. Whereas some clinal patterns are clearly adaptive, the causes of others remain obscure. We investigated intra-specific body size, development time and female fecundity (egg size and number) clines across 13 European populations of the dung fly Sepsis fulgens spanning 20° latitude from southern Italy to Estonia in a genetic common garden approach. Despite very short generation times (ca. 2 weeks at 24 °C), we found a converse Bergmann cline (smaller size at higher latitudes). As development time did not change with latitude (flat cline), integral growth rate thus likely declines towards the pole. At the same time, early fecundity, but not egg size, increased with latitude. Rather than being mediated by seasonal time constraints, the body size reduction in the northernmost flies from Estonia could suggest that these are marginal, edge populations, as when omitting them the body size cline became flat as well. Most of the other sepsid species investigated to date also show flat body size clines, a pattern that strikingly differs from Drosophila. We conclude that S. fulgens life history traits appear to be shaped by similar environmental pressures and selective mechanisms across Europe, be they adaptive or not. This reiterates the suggestion that body size clines can result as a secondary consequence of selection pressures shaping an entire life history syndrome, rendering them inconsistent and unpredictable in general.

Delineating modern variation from extinct morphology in the fossil record using shells of the Eastern Box Turtle (Terrapene carolina)

PubMed Central

2018-01-01

Characterization of morphological variation in the shells of extant Eastern Box Turtles, Terrapene carolina, provides a baseline for comparison to fossil populations. It also provides an example of the difficulties inherent to recognizing intraspecific diversity in the fossil record. The degree to which variation in fossils of T. carolina can be accommodated by extant variation in the species has been disagreed upon for over eighty years. Using morphometric analyses of the carapace, I address the relationship between modern and fossil T. carolina in terms of sexual dimorphism, geographic and subspecific variation, and allometric variation. Modern T. carolina display weak male-biased sexual size dimorphism. Sexual shape dimorphism cannot be reliably detected in the fossil record. Rather than a four-part subspecific division, patterns of geographic variation are more consistent with clinal variation between various regions in the species distribution. Allometric patterns are qualitatively similar to those documented in other emydid turtles and explain a significant amount of shape variation. When allometric patterns are accounted for, Holocene specimens are not significantly different from modern specimens. In contrast, several geologically older specimens have significantly different carapace shape with no modern analogue. Those large, fossilized specimens represent extinct variation occupying novel portions of morphospace. This study highlights the need for additional documentation of modern osteological variation that can be used to test hypotheses of intraspecific evolution in the fossil record. PMID:29513709

Phenotypic variation of the Mexican duck (Anas platyrhynchos diazi) in Mexico

USGS Publications Warehouse

Scott, N.J.; Reynolds, R.P.

1984-01-01

A collection of 98 breeding Mexican Ducks (Anas platyrhynchos diazi) was made in Mexico from six areas between the United States border with Chihuahua and Lake Chapala, Jalisco, in order to study geographic variation. Plumage indices showed a relatively smooth clinal change from north to south; northern populations were most influenced by the Northern Mallard (A. platyrhynchos) phenotype. Measurements of total, wing, and culmen lengths and bill width were usually significantly larger in males at any one site, but showed no regular geographic trends. Hybridization between platyrhynchos and diazi phenotypes may or may not be increasing in the middle Rio Grande and Rio Conchos valleys; available data are insufficient to decide. A spring 1978 aerial census yielded an estimate of 55,500 diazi -like birds in Mexico. Populations of diazi appear to be as large as the available habitat allows; management should be directed towards increasing and stabilizing the nesting habitat; and the stability of the zone of intergradation should be investigated.

Barriers to Gene Flow in the Marine Environment: Insights from Two Common Intertidal Limpet Species of the Atlantic and Mediterranean

PubMed Central

Sá-Pinto, Alexandra; Branco, Madalena S.; Alexandrino, Paulo B.; Fontaine, Michaël C.; Baird, Stuart J. E.

2012-01-01

Knowledge of the scale of dispersal and the mechanisms governing gene flow in marine environments remains fragmentary despite being essential for understanding evolution of marine biota and to design management plans. We use the limpets Patella ulyssiponensis and Patella rustica as models for identifying factors affecting gene flow in marine organisms across the North-East Atlantic and the Mediterranean Sea. A set of allozyme loci and a fragment of the mitochondrial gene cytochrome C oxidase subunit I were screened for genetic variation through starch gel electrophoresis and DNA sequencing, respectively. An approach combining clustering algorithms with clinal analyses was used to test for the existence of barriers to gene flow and estimate their geographic location and abruptness. Sharp breaks in the genetic composition of individuals were observed in the transitions between the Atlantic and the Mediterranean and across southern Italian shores. An additional break within the Atlantic cluster separates samples from the Alboran Sea and Atlantic African shores from those of the Iberian Atlantic shores. The geographic congruence of the genetic breaks detected in these two limpet species strongly supports the existence of transpecific barriers to gene flow in the Mediterranean Sea and Northeastern Atlantic. This leads to testable hypotheses regarding factors restricting gene flow across the study area. PMID:23239977

sGD: software for estimating spatially explicit indices of genetic diversity.

PubMed

Shirk, A J; Cushman, S A

2011-09-01

Anthropogenic landscape changes have greatly reduced the population size, range and migration rates of many terrestrial species. The small local effective population size of remnant populations favours loss of genetic diversity leading to reduced fitness and adaptive potential, and thus ultimately greater extinction risk. Accurately quantifying genetic diversity is therefore crucial to assessing the viability of small populations. Diversity indices are typically calculated from the multilocus genotypes of all individuals sampled within discretely defined habitat patches or larger regional extents. Importantly, discrete population approaches do not capture the clinal nature of populations genetically isolated by distance or landscape resistance. Here, we introduce spatial Genetic Diversity (sGD), a new spatially explicit tool to estimate genetic diversity based on grouping individuals into potentially overlapping genetic neighbourhoods that match the population structure, whether discrete or clinal. We compared the estimates and patterns of genetic diversity using patch or regional sampling and sGD on both simulated and empirical populations. When the population did not meet the assumptions of an island model, we found that patch and regional sampling generally overestimated local heterozygosity, inbreeding and allelic diversity. Moreover, sGD revealed fine-scale spatial heterogeneity in genetic diversity that was not evident with patch or regional sampling. These advantages should provide a more robust means to evaluate the potential for genetic factors to influence the viability of clinal populations and guide appropriate conservation plans. © 2011 Blackwell Publishing Ltd.

Patterns of gene variation in central and marginal populations of Drosophila robusta.

PubMed

Prakash, S

1973-10-01

The central and marginal populations of D. robusta differ greatly in the level of inversion polymorphism; the marginal populations are monomorphic or nearly so and the central populations are highly polymorphic. This paper presents the frequencies of alleles at forty gene loci in various populations of D. robusta, studied by electrophoresis of proteins and enzymes. Population samples were obtained from eight widely separated populations of D. robusta which included the central, the extreme marginal and the intervening populations between the center and the margins. We find that the proportion of polymorphic loci and average heterozygosity per individual is slightly higher in the marginal populations than the central populations. In D. robusta on an average, 39% of the loci are polymorphic and the average proportion of loci heterozygous per individual is 11%. A breakdown of loci in three categories, viz, hydrolytic enzymes and some other enzymes, larval proteins and glycolytic and Kreb's cycle enzymes, shows that in all populations the level of polymorphism is highest in the hydrolytic enzymes, intermediate in larval proteins and least in the glycolytic and Kreb's cycle enzymes. On the average, the proportion of loci heterozygous per individual for three groups of loci is: hydrolytic enzymes and others (.164), larval proteins (.115) and glycolytic and Kreb's cycle enzymes (.037). We also observe that in all populations the level of polymorphism on the X chromosome is far less than the expected 38%; in salivary gland cells the euchromatic length of the X chromosome is 38% of the entire genome. Lower levels of polymorphism for the X chromosome loci are explained due to low probability of balanced polymorphisms for the X-linked loci since the conditions for establishment of balanced polymorphism for X-linked loci are more restrictive than for the autosomal loci.-The polymorphic loci can be grouped according to pattern of allele frequencies in different populations as follows: (1) The allele frequencies are similar in all populations at the XDH, Pep-1 and Hex-1 loci. (2) The alleles at the Est-1, Est-2, Amy loci and the AP-4(1.0) and the LAP-1(.90) alleles show north south clinal change in frequency. (3) There is north south and east west differentiation at the Pt-5, Pt-8 and Pt-9 loci and the allele AP-4(.81). (4) Polymorphism at loci such as Fum, B.Ox, Hex-8, Pep-2 and Pep-3 are restricted to only one or two of the populations. (5) Allele frequencies at the MDH and ODH loci fluctuate between populations. (6) Allele frequencies at many polymorphic loci such as Est-1, Est-2, LAP-1, AP-4, Pt-5, Pt-8, Pt-9, Pt-16, MDH, Fum change clinally within a gene arrangement. The pattern of gene variation in D. robusta is very complex and cannot be easily explained due to migration of neutral alleles between once-isolated populations or to semi-isolation of neutral alleles. The observations of the pattern of allele variation in different populations, high levels of polymorphism in the marginal populations which have small population size and low levels of polymorphism of the X chromosome loci all support the argument in favor of balancing selection as the main mechanism for the maintenance of these polymorphisms. Environmental factors must play a role in the maintenance of a great deal of these polymorphisms, since we observe clinal allele frequency changes even within a given inversion type.

Patterns of Gene Variation in Central and Marginal Populations of DROSOPHILA ROBUSTA

PubMed Central

Prakash, Satya

1973-01-01

The central and marginal populations of D. robusta differ greatly in the level of inversion polymorphism; the marginal populations are monomorphic or nearly so and the central populations are highly polymorphic. This paper presents the frequencies of alleles at forty gene loci in various populations of D. robusta, studied by electrophoresis of proteins and enzymes. Population samples were obtained from eight widely separated populations of D. robusta which included the central, the extreme marginal and the intervening populations between the center and the margins. We find that the proportion of polymorphic loci and average heterozygosity per individual is slightly higher in the marginal populations than the central populations. In D. robusta on an average, 39% of the loci are polymorphic and the average proportion of loci heterozygous per individual is 11%. A breakdown of loci in three categories, viz, hydrolytic enzymes and some other enzymes, larval proteins and glycolytic and Kreb's cycle enzymes, shows that in all populations the level of polymorphism is highest in the hydrolytic enzymes, intermediate in larval proteins and least in the glycolytic and Kreb's cycle enzymes. On the average, the proportion of loci heterozygous per individual for three groups of loci is: hydrolytic enzymes and others (.164), larval proteins (.115) and glycolytic and Kreb's cycle enzymes (.037). We also observe that in all populations the level of polymorphism on the X chromosome is far less than the expected 38%; in salivary gland cells the euchromatic length of the X chromosome is 38% of the entire genome. Lower levels of polymorphism for the X chromosome loci are explained due to low probability of balanced polymorphisms for the X-linked loci since the conditions for establishment of balanced polymorphism for X-linked loci are more restrictive than for the autosomal loci.—The polymorphic loci can be grouped according to pattern of allele frequencies in different populations as follows: (1) The allele frequencies are similar in all populations at the XDH, Pep-1 and Hex-1 loci. (2) The alleles at the Est-1, Est-2, Amy loci and the AP-41.0 and the LAP-1.90 alleles show north south clinal change in frequency. (3) There is north south and east west differentiation at the Pt-5, Pt-8 and Pt-9 loci and the allele AP-4.81. (4) Polymorphism at loci such as Fum, B.Ox, Hex-8, Pep-2 and Pep-3 are restricted to only one or two of the populations. (5) Allele frequencies at the MDH and ODH loci fluctuate between populations. (6) Allele frequencies at many polymorphic loci such as Est-1, Est-2, LAP-1, AP-4, Pt-5, Pt-8, Pt-9, Pt-16, MDH, Fum change clinally within a gene arrangement. The pattern of gene variation in D. robusta is very complex and cannot be easily explained due to migration of neutral alleles between once-isolated populations or to semi-isolation of neutral alleles. The observations of the pattern of allele variation in different populations, high levels of polymorphism in the marginal populations which have small population size and low levels of polymorphism of the X chromosome loci all support the argument in favor of balancing selection as the main mechanism for the maintenance of these polymorphisms. Environmental factors must play a role in the maintenance of a great deal of these polymorphisms, since we observe clinal allele frequency changes even within a given inversion type. PMID:4203580

Parallel Evolution of Copy-Number Variation across Continents in Drosophila melanogaster

PubMed Central

Schrider, Daniel R.; Hahn, Matthew W.; Begun, David J.

2016-01-01

Genetic differentiation across populations that is maintained in the presence of gene flow is a hallmark of spatially varying selection. In Drosophila melanogaster, the latitudinal clines across the eastern coasts of Australia and North America appear to be examples of this type of selection, with recent studies showing that a substantial portion of the D. melanogaster genome exhibits allele frequency differentiation with respect to latitude on both continents. As of yet there has been no genome-wide examination of differentiated copy-number variants (CNVs) in these geographic regions, despite their potential importance for phenotypic variation in Drosophila and other taxa. Here, we present an analysis of geographic variation in CNVs in D. melanogaster. We also present the first genomic analysis of geographic variation for copy-number variation in the sister species, D. simulans, in order to investigate patterns of parallel evolution in these close relatives. In D. melanogaster we find hundreds of CNVs, many of which show parallel patterns of geographic variation on both continents, lending support to the idea that they are influenced by spatially varying selection. These findings support the idea that polymorphic CNVs contribute to local adaptation in D. melanogaster. In contrast, we find very few CNVs in D. simulans that are geographically differentiated in parallel on both continents, consistent with earlier work suggesting that clinal patterns are weaker in this species. PMID:26809315

Latitudinal variation in seasonal activity and mortality in ratsnakes (Elaphe obsoleta).

PubMed

Sperry, Jinelle H; Blouin-Demers, Gabriel; Carfagno, Gerardo L F; Weatherhead, Patrick J

2010-06-01

The ecology of ectotherms should be particularly affected by latitude because so much of their biology is temperature dependent. Current latitudinal patterns should also be informative about how ectotherms will have to modify their behavior in response to climate change. We used data from a total of 175 adult black ratsnakes (Elaphe obsoleta) radio-tracked in Ontario, Illinois, and Texas, a latitudinal distance of >1500 km, to test predictions about how seasonal patterns of activity and mortality should vary with latitude. Despite pronounced differences in temperatures among study locations, and despite ratsnakes in Texas not hibernating and switching from diurnal to nocturnal activity in the summer, seasonal patterns of snake activity were remarkably similar during the months that snakes in all populations were active. Rather than being a function of temperature, activity may be driven by the timing of reproduction, which appears similar among populations. Contrary to the prediction that mortality should be highest in the most active population, overall mortality did not follow a clinal pattern. Winter mortality did increase with latitude, however, consistent with temperature limiting the northern distribution of ratsnakes. This result was opposite that found in the only previous study of latitudinal variation in winter mortality in reptiles, which may be a consequence of whether or not the animals exhibit true hibernation. Collectively, these results suggest that, at least in the northern part of their range, ratsnakes should be able to adjust easily to, and may benefit from, a warmer climate, although climate-based changes to the snakes' prey or habitat, for example, could alter that prediction.

Pelage Variation and Distribution of the Black Lion Tamarin, Leontopithecus chrysopygus.

PubMed

Garbino, Guilherme Siniciato Terra; Rezende, Gabriela Cabral; Valladares-Padua, Claudio

2016-01-01

The black lion tamarin, Leontopithecus chrysopygus, is endemic to the Atlantic Forest of the interior of the state of São Paulo in Brazil. Since the discovery of the species, authors have described variations in the pelage of L. chrysopygus, but the nature of this variation has remained unknown. We examined museum specimens and living animals to see if the pelage of L. chrysopygus varies individually, geographically or ontogenetically. We reviewed all known locality records of the species, and concluded that the pelage of L. chrysopygus varies individually and ontogenetically, but not geographically. The extent of the golden chromogenetic fields is larger in younger individuals, and the pelage becomes darker after successive moults. We examined 2 juveniles that presented a pelage similar to adult L. caissara. Geographically, there is a clear break in the phenotypes attributed to L. caissara and L. chrysopygus, precluding clinal variation and corroborating the specific status of the former. The separation between these 2 species is coincident with a tectonic fault known as the 'Guapiara lineament', and may have been caused by a recent activation of this geological formation. We also suggest a historical contact zone between L. chrysopygus and the marmoset Callithrix aurita in the upper Rio Tietê region. © 2016 S. Karger AG, Basel.

Longitudinal trends in climate drive flowering time clines in North American Arabidopsis thaliana.

PubMed

Samis, Karen E; Murren, Courtney J; Bossdorf, Oliver; Donohue, Kathleen; Fenster, Charles B; Malmberg, Russell L; Purugganan, Michael D; Stinchcombe, John R

2012-06-01

Introduced species frequently show geographic differentiation, and when differentiation mirrors the ancestral range, it is often taken as evidence of adaptive evolution. The mouse-ear cress (Arabidopsis thaliana) was introduced to North America from Eurasia 150-200 years ago, providing an opportunity to study parallel adaptation in a genetic model organism. Here, we test for clinal variation in flowering time using 199 North American (NA) accessions of A. thaliana, and evaluate the contributions of major flowering time genes FRI, FLC, and PHYC as well as potential ecological mechanisms underlying differentiation. We find evidence for substantial within population genetic variation in quantitative traits and flowering time, and putatively adaptive longitudinal differentiation, despite low levels of variation at FRI, FLC, and PHYC and genome-wide reductions in population structure relative to Eurasian (EA) samples. The observed longitudinal cline in flowering time in North America is parallel to an EA cline, robust to the effects of population structure, and associated with geographic variation in winter precipitation and temperature. We detected major effects of FRI on quantitative traits associated with reproductive fitness, although the haplotype associated with higher fitness remains rare in North America. Collectively, our results suggest the evolution of parallel flowering time clines through novel genetic mechanisms.

Comparative morphology among northern populations of breeding Cooper's Hawks

USGS Publications Warehouse

Rosenfield, Robert N.; Rosenfield, Laura J.; Bielefeldt, John; Murphy, Robert K.; Stewart, Andrew C.; Stout, William E.; Driscoll, Timothy G.; Bozek, Michael A.

2010-01-01

Few studies at a broad geographical scale have characterized intraspecific variation in morphology of woodland hawks in the genus Accipiter. From 1999 to 2007 we investigated morphological variation in large samples of live Cooper's Hawks (A. cooperii) nesting in four study areas: coniferous woodland around Victoria, British Columbia, Canada, isolated deciduous woodlands in short-grass prairies of northwestern North Dakota, towns and rural deciduous woodlands along the border of North Dakota and Minnesota, and urban and rural mixed deciduous and coniferous landscapes of Wisconsin. These sites span 2660 km across the northern part of the species' breeding range. We measured body mass (i.e., size), wing chord, tail length, tarsus diameter, hallux length, and culmen length of breeding adults, finding significant and clinal variation in body mass (or size). The smallest and most similar-sized birds occurred in British Columbia and western North Dakota, larger birds along the border between North Dakota and Minnesota, and the largest birds in Wisconsin. Several other characters varied significantly when mass was used as a covariate. Variation by study site in mean indices of sexual size dimorphism was negligible and not significant. We speculate that the morphological differences we found, in part, are the result of geographic isolation, where diets, migratory behavior, and structural characteristics of nesting habitats vary across landscape types.

Quantifying in situ phenotypic variability in the hydraulic properties of four tree species across their distribution range in Europe

PubMed Central

Sterck, F.; Torres-Ruiz, J. M.; Petit, G.; Cochard, H.; von Arx, G.; Lintunen, A.; Caldeira, M. C.; Capdeville, G.; Copini, P.; Gebauer, R.; Grönlund, L.; Hölttä, T.; Lobo-do-Vale, R.; Peltoniemi, M.; Stritih, A.; Urban, J.; Delzon, S.

2018-01-01

Many studies have reported that hydraulic properties vary considerably between tree species, but little is known about their intraspecific variation and, therefore, their capacity to adapt to a warmer and drier climate. Here, we quantify phenotypic divergence and clinal variation for embolism resistance, hydraulic conductivity and branch growth, in four tree species, two angiosperms (Betula pendula, Populus tremula) and two conifers (Picea abies, Pinus sylvestris), across their latitudinal distribution in Europe. Growth and hydraulic efficiency varied widely within species and between populations. The variability of embolism resistance was in general weaker than that of growth and hydraulic efficiency, and very low for all species but Populus tremula. In addition, no and weak support for a safety vs. efficiency trade-off was observed for the angiosperm and conifer species, respectively. The limited variability of embolism resistance observed here for all species except Populus tremula, suggests that forest populations will unlikely be able to adapt hydraulically to drier conditions through the evolution of embolism resistance. PMID:29715289

Geographic variation in body size and its relationship with environmental gradients in the Oriental Garden Lizard, Calotes versicolor.

PubMed

Wei, Xiaomei; Yan, Linmiao; Zhao, Chengjian; Zhang, Yueyun; Xu, Yongli; Cai, Bo; Jiang, Ni; Huang, Yong

2018-05-01

Patterns of geographic variation in body size are predicted to evolve as adaptations to local environmental gradients. However, many of these clinal patterns in body size, such as Bergmann's rule, are controversial and require further investigation into ectotherms such as reptiles on a regional scale. To examine the environmental variables (temperature, precipitation, topography and primary productivity) that shaped patterns of geographic variation in body size in the reptile Calotes versicolor , we sampled 180 adult specimens (91 males and 89 females) at 40 locations across the species range in China. The MANOVA results suggest significant sexual size dimorphism in C. versicolor ( F 23,124  = 11.32, p  < .001). Our results showed that C. versicolor failed to fit the Bergmann's rule. We found that the most important predictors of variation in body size of C. versicolor differed for males and females, but mechanisms related to heat balance and water availability hypotheses were involved in both sexes. Temperature seasonality, precipitation of the driest month, precipitation seasonality, and precipitation of the driest quarter were the most important predictors of variation in body size in males, whereas mean precipitation of the warmest quarter, mean temperature of the wettest quarter, precipitation seasonality, and precipitation of the wettest month were most important for body size variation in females. The discrepancy between patterns of association between the sexes suggested that different selection pressures may be acting in males and females.

FLOWERING LOCUS T/TERMINAL FLOWER1-like genes affect growth rhythm and bud set in Norway spruce.

PubMed

Karlgren, Anna; Gyllenstrand, Niclas; Clapham, David; Lagercrantz, Ulf

2013-10-01

The timing of bud set, as one determinant of the annual growth rhythm, is critical for local adaptation of the conifer Norway spruce (Picea abies). Previous gene expression and population genetic studies have suggested a role for P. abies FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (PaFTL2) in the control of growth cessation and bud set in Norway spruce as well as in local adaptation resulting in clinal variation for timing of bud set. Using transgenic plants with PaFTL2 driven by an inducible promoter, we found that PaFTL2 indeed induces bud set and most probably also growth cessation. PaFTL2 shows high expression around the procambium and vascular tissue and in the crown region in buds of both seedlings and older trees. Furthermore, PaFTL2 expression is induced in vegetative shoots and all bud types in late summer, when growth cessation occurs. This supports the notion that PaFTL2 is involved in growth cessation. A close paralog to PaFTL2, PaFTL1, is strongly expressed in meristems during the summer, possibly to repress meristem activity and the formation of needle primordia during this period. The temporal and spatial expression of PaFTL1 and PaFTL2 largely complement each other, which suggests that they act in concert to control perennial growth in Norway spruce.

Phylogeographic structure across one of the largest intact tropical savannahs: Molecular and morphological analysis of Australia's iconic frilled lizard Chlamydosaurus kingii.

PubMed

Pepper, Mitzy; Hamilton, David G; Merkling, Thomas; Svedin, Nina; Cser, Bori; Catullo, Renee A; Pryke, Sarah R; Keogh, J Scott

2017-01-01

The spectacular threat display of the savannah specialist Australo-Papuan frilled lizards has made them one of the world's most iconic reptiles. They are increasingly used as a model system for research in evolutionary biology and ecology but little is known of their population structure. Their distribution across northern Australia and southern New Guinea also provides an opportunity to examine biogeographic patterns as they relate to the large-scale movement of savannah habitat during the Plio/Pleistocene and the associated increase in aridity. We generated sequence data for one mitochondrial and four nuclear DNA loci (5052 base pairs) for 83 frilled lizards sampled throughout their range. We also quantified body proportion variation for 279 individuals. Phylogenetic analyses based on maximum likelihood and Bayesian species-tree methods revealed three shallow clades that replace each other across the monsoon tropics. We found the expected pattern of male biased sexual size dimorphism in both maximum body size and head size but there was no sexual dimorphism in overall body shape or in frill size, relative to head size, supporting the hypothesis that the frill is used primarily as a threat display rather than a sexual display. The genetic clades are broadly consistent with known clinal variation in frill color that gradually shifts from west to east (red, orange, yellow/white) but otherwise show little morphological differentiation in body proportion measures. The biogeographic breaks between clades occur at the Carpentaria Gap and the lowlands surrounding the Ord River, and our ecological niche modeling predicts lower habitat suitability for C. kingii in these regions. While this biogeographic pattern is consistent with numerous other taxonomic groups in northern Australia, the overall low genetic diversity in frilled lizards across the entire monsoon tropics and southern New Guinea contrasts starkly to patterns seen in other terrestrial vertebrates. Extremely low intra-clade genetic diversity over vast geographic areas is indicative of recent gene flow that would likely have been facilitated by widespread savannah during interglacials, or alternatively may reflect population bottlenecks induced by extreme aridity during Pleistocene glacials. The shallow divergence between Australian and New Guinean samples is consistent with recent connectivity between Australia and New Guinea that would have been possible via a savannah corridor across the Torres Strait. Based on our molecular and morphological data, we do not support taxonomic recognition of any of the frilled lizard clades and instead consider C. kingii a single species with shallow phylogeographic structure and clinal variation in frill color. Copyright © 2016 Elsevier Inc. All rights reserved.

Tropical anurans mature early and die young: Evidence from eight Afromontane Hyperolius species and a meta-analysis

PubMed Central

2017-01-01

Age- and size-related life-history traits of anuran amphibians are thought to vary systematically with latitude and altitude. Because the available data base is strongly biased towards temperate-zone species, we provide new estimates on eight afrotropical Reed Frog species. A meta-analysis of the demographic traits in 44 tropical anuran species aims to test for the predicted clinal variation and to contrast results with variation detected in temperate-zone species. The small-sized reed frogs reach sexual maturity during the first or second year of life, but longevity does not exceed three to four years. Latitudinal effects on demographic life-history traits are not detectable in tropical anurans, and altitudinal effects are limited to a slight size reduction at higher elevations. Common features of anuran life-history in the tropics are early sexual maturation at small size and low longevity resulting in low lifetime fecundity. This pattern contrasts with that found in temperate-zone anurans which mature later at larger size and grow considerably older yielding greater lifetime fecundity than in the tropics. Latitudinal and altitudinal contraction of the yearly activity period shape the evolution of life-history traits in the temperate region, while trait variation in the tropics seems to be driven by distinct, not yet identified selective forces. PMID:28182738

Processes affecting altitudinal distribution of invasive Ageratina adenophora in western Himalaya: The role of local adaptation and the importance of different life-cycle stages

PubMed Central

Kühn, Ingolf; Ahmad, Mustaqeem; Michalski, Stefan; Auge, Harald

2017-01-01

The spread of invasive plants along elevational gradients is considered a threat to fragile mountain ecosystems, but it can also provide the opportunity to better understand some of the basic processes driving the success of invasive species. Ageratina adenophora (Asteraceae) is an invasive plant of global importance and has a broad distribution along elevational gradients in the Western Himalayas. Our study aimed at understanding the role of evolutionary processes (e.g. local adaptation and clinal differentiation) and different life history stages in shaping the distribution pattern of the invasive plant along an elevational gradient in the Western Himalaya. We carried out extensive distributional surveys, established a reciprocal transplant experiment with common gardens at three elevational levels, and measured a suite of traits related to germination, growth, reproduction and phenology. Our results showed a lack of local adaptation, and we did not find any evidence for clinal differentiation in any measured trait except a rather weak signal for plant height. We found that seed germination was the crucial life-cycle transition in determining the lower range limit while winter mortality of plants shaped the upper range limit in our study area, thus explaining the hump shaped distribution pattern. Differences in trait values between gardens for most traits indicated a high degree of phenotypic plasticity. Possible causes such as apomixis, seed dispersal among sites, and pre-adaptation might have confounded evolutionary processes to act upon. Our results suggest that the success and spread of Ageratina adenophora are dependent on different life history stages at different elevations that are controlled by abiotic conditions. PMID:29125852

Processes affecting altitudinal distribution of invasive Ageratina adenophora in western Himalaya: The role of local adaptation and the importance of different life-cycle stages.

PubMed

Datta, Arunava; Kühn, Ingolf; Ahmad, Mustaqeem; Michalski, Stefan; Auge, Harald

2017-01-01

The spread of invasive plants along elevational gradients is considered a threat to fragile mountain ecosystems, but it can also provide the opportunity to better understand some of the basic processes driving the success of invasive species. Ageratina adenophora (Asteraceae) is an invasive plant of global importance and has a broad distribution along elevational gradients in the Western Himalayas. Our study aimed at understanding the role of evolutionary processes (e.g. local adaptation and clinal differentiation) and different life history stages in shaping the distribution pattern of the invasive plant along an elevational gradient in the Western Himalaya. We carried out extensive distributional surveys, established a reciprocal transplant experiment with common gardens at three elevational levels, and measured a suite of traits related to germination, growth, reproduction and phenology. Our results showed a lack of local adaptation, and we did not find any evidence for clinal differentiation in any measured trait except a rather weak signal for plant height. We found that seed germination was the crucial life-cycle transition in determining the lower range limit while winter mortality of plants shaped the upper range limit in our study area, thus explaining the hump shaped distribution pattern. Differences in trait values between gardens for most traits indicated a high degree of phenotypic plasticity. Possible causes such as apomixis, seed dispersal among sites, and pre-adaptation might have confounded evolutionary processes to act upon. Our results suggest that the success and spread of Ageratina adenophora are dependent on different life history stages at different elevations that are controlled by abiotic conditions.

Parallel Evolution of Copy-Number Variation across Continents in Drosophila melanogaster.

PubMed

Schrider, Daniel R; Hahn, Matthew W; Begun, David J

2016-05-01

Genetic differentiation across populations that is maintained in the presence of gene flow is a hallmark of spatially varying selection. In Drosophila melanogaster, the latitudinal clines across the eastern coasts of Australia and North America appear to be examples of this type of selection, with recent studies showing that a substantial portion of the D. melanogaster genome exhibits allele frequency differentiation with respect to latitude on both continents. As of yet there has been no genome-wide examination of differentiated copy-number variants (CNVs) in these geographic regions, despite their potential importance for phenotypic variation in Drosophila and other taxa. Here, we present an analysis of geographic variation in CNVs in D. melanogaster. We also present the first genomic analysis of geographic variation for copy-number variation in the sister species, D. simulans, in order to investigate patterns of parallel evolution in these close relatives. In D. melanogaster we find hundreds of CNVs, many of which show parallel patterns of geographic variation on both continents, lending support to the idea that they are influenced by spatially varying selection. These findings support the idea that polymorphic CNVs contribute to local adaptation in D. melanogaster In contrast, we find very few CNVs in D. simulans that are geographically differentiated in parallel on both continents, consistent with earlier work suggesting that clinal patterns are weaker in this species. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Oceanographic variation influences spatial genomic structure in the sea scallop, Placopecten magellanicus.

PubMed

Van Wyngaarden, Mallory; Snelgrove, Paul V R; DiBacco, Claudio; Hamilton, Lorraine C; Rodríguez-Ezpeleta, Naiara; Zhan, Luyao; Beiko, Robert G; Bradbury, Ian R

2018-03-01

Environmental factors can influence diversity and population structure in marine species and accurate understanding of this influence can both improve fisheries management and help predict responses to environmental change. We used 7163 SNPs derived from restriction site-associated DNA sequencing genotyped in 245 individuals of the economically important sea scallop, Placopecten magellanicus , to evaluate the correlations between oceanographic variation and a previously identified latitudinal genomic cline. Sea scallops span a broad latitudinal area (>10 degrees), and we hypothesized that climatic variation significantly drives clinal trends in allele frequency. Using a large environmental dataset, including temperature, salinity, chlorophyll a, and nutrient concentrations, we identified a suite of SNPs (285-621, depending on analysis and environmental dataset) potentially under selection through correlations with environmental variation. Principal components analysis of different outlier SNPs and environmental datasets revealed similar northern and southern clusters, with significant associations between the first axes of each ( R 2 adj  = .66-.79). Multivariate redundancy analysis of outlier SNPs and the environmental principal components indicated that environmental factors explained more than 32% of the variance. Similarly, multiple linear regressions and random-forest analysis identified winter average and minimum ocean temperatures as significant parameters in the link between genetic and environmental variation. This work indicates that oceanographic variation is associated with the observed genomic cline in this species and that seasonal periods of extreme cold may restrict gene flow along a latitudinal gradient in this marine benthic bivalve. Incorporating this finding into management may improve accuracy of management strategies and future predictions.

Discordant introgression in a rapidly expanding hybrid swarm

USGS Publications Warehouse

Ward, Jessica L.; Blum, Mike J.; Walters, David M.; Porter, Brady A.; Burkhead, Noel; Freeman, Byron

2012-01-01

The erosion of species boundaries can involve rapid evolutionary change. Consequently, many aspects of the process remain poorly understood, including the formation, expansion, and evolution of hybrid swarms. Biological invasions involving hybridization present exceptional opportunities to study the erosion of species boundaries because timelines of interactions and outcomes are frequently well known. Here, we examined clinal variation across codominant and maternally inherited genetic markers as well as phenotypic traits to characterize the expansion and evolution of a hybrid swarm between native Cyprinella venusta and invasive Cyprinella lutrensis minnows. Discordant introgression of phenotype, microsatellite multilocus genotype, and mtDNA haplotype indicates that the observable expansion of the C. venusta x C. lutrensis hybrid swarm is a false invasion front. Both parental and hybrid individuals closely resembling C. lutrensis are numerically dominant in the expansion wake, indicating that the non-native parental phenotype may be selectively favored. These findings show that cryptic introgression can extend beyond the phenotypic boundaries of hybrid swarms and that hybrid swarms likely expand more rapidly than can be documented from phenotypic variation alone. Similarly, dominance of a single parental phenotype following an introduction event may lead to instances of species erosion being mistaken for species displacement without hybridization.

Taxonomic revision of Drymoluber Amaral, 1930 (Serpentes: Colubridae).

PubMed

Costa, Henrique Caldeira; Moura, Mário Ribeiro; Feio, Renato Neves

2013-01-01

The present study is a taxonomic revision of the genus Drymoluber Amaral, 1930, using meristic and morphometric characters, aspects of external hemipenial morphology and body coloration. Sexual dimorphism occurs in D. dichrous and D. brazili but was not detected in D. apurimacensis. Morphological variation within D. dichrous is related to geographic distance between populations. Furthermore, variation in the number of ventrals and subcaudals in D. dichrous and D. brazili follows latitudinal and longitudinal clinal patterns. Drymoluber dichrous is diagnosed by the presence of 15-15-15 smooth dorsal scale rows with two apical pits, and 157-180 ventrals and 86-110 subcaudals; it occurs along the eastern versant of the Andes, in the Amazon forest, on the Guiana Shield, in the Atlantic forest, and its transitional areas with the Caatinga and Cerrado. Drymoluber brazili has 17-17-15 smooth dorsal scale rows with two apical pits, 182-202 ventrals and 109-127 subcaudals, and ranges throughout the Caatinga, Cerrado, Atlantic forest and transitional areas between these last two domains. Drymoluber apurimacensis has 13-13-13 smooth dorsal scale rows without apical pits, 158-182 ventrals and 84-93 subcaudals, and occurs in the Apurimac Valley, south of the Apurimac and Pampas rivers in Peru.

The epigenetic memory of temperature during embryogenesis modifies the expression of bud burst-related genes in Norway spruce epitypes.

PubMed

Carneros, Elena; Yakovlev, Igor; Viejo, Marcos; Olsen, Jorunn E; Fossdal, Carl Gunnar

2017-09-01

Epigenetic memory affects the timing of bud burst phenology and the expression of bud burst-related genes in genetically identical Norway spruce epitypes in a manner usually associated with ecotypes. In Norway spruce, a temperature-dependent epigenetic memory established during embryogenesis affects the timing of bud burst and bud set in a reproducible and predictable manner. We hypothesize that the clinal variation in these phenological traits, which is associated with adaptation to growth under frost-free conditions, has an epigenetic component. In Norway spruce, dehydrins (DHNs) have been associated with extreme frost tolerance. DHN transcript levels decrease gradually prior to flushing, a time when trees are highly sensitive to frost. Furthermore, EARLY BUD BREAK 1 genes (EBB1) and the FT-TFL1-LIKE 2-gene (PaFTL2) were previously suggested to be implied in control of bud phenology. Here we report an analysis of transcript levels of 12 DHNs, 3 EBB1 genes and FTL2 in epitypes of the same genotype generated at different epitype-inducing temperatures, before and during spring bud burst. Earlier flushing of epitypes originating from embryos developed at 18 °C as compared to 28 °C, was associated with differential expression of these genes between epitypes and between buds and last year's needles. The majority of these genes showed significantly different expressions between epitypes in at least one time point. The general trend in DHN expression pattern in buds showed the expected reduction in transcript levels when approaching flushing, whereas, surprisingly, transcript levels peaked later in needles, mainly at the moment of bud burst. Collectively, our results demonstrate that the epigenetic memory of temperature during embryogenesis affects bud burst phenology and expression of the bud burst-related DHN, EBB1 and FTL2 genes in genetically identical Norway spruce epitypes.

FLOWERING LOCUS T/TERMINAL FLOWER1-Like Genes Affect Growth Rhythm and Bud Set in Norway Spruce1[W][OPEN

PubMed Central

Karlgren, Anna; Gyllenstrand, Niclas; Clapham, David; Lagercrantz, Ulf

2013-01-01

The timing of bud set, as one determinant of the annual growth rhythm, is critical for local adaptation of the conifer Norway spruce (Picea abies). Previous gene expression and population genetic studies have suggested a role for P. abies FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (PaFTL2) in the control of growth cessation and bud set in Norway spruce as well as in local adaptation resulting in clinal variation for timing of bud set. Using transgenic plants with PaFTL2 driven by an inducible promoter, we found that PaFTL2 indeed induces bud set and most probably also growth cessation. PaFTL2 shows high expression around the procambium and vascular tissue and in the crown region in buds of both seedlings and older trees. Furthermore, PaFTL2 expression is induced in vegetative shoots and all bud types in late summer, when growth cessation occurs. This supports the notion that PaFTL2 is involved in growth cessation. A close paralog to PaFTL2, PaFTL1, is strongly expressed in meristems during the summer, possibly to repress meristem activity and the formation of needle primordia during this period. The temporal and spatial expression of PaFTL1 and PaFTL2 largely complement each other, which suggests that they act in concert to control perennial growth in Norway spruce. PMID:23958861

Parallel altitudinal clines reveal trends in adaptive evolution of genome size in Zea mays

PubMed Central

Berg, Jeremy J.; Birchler, James A.; Grote, Mark N.; Lorant, Anne; Quezada, Juvenal

2018-01-01

While the vast majority of genome size variation in plants is due to differences in repetitive sequence, we know little about how selection acts on repeat content in natural populations. Here we investigate parallel changes in intraspecific genome size and repeat content of domesticated maize (Zea mays) landraces and their wild relative teosinte across altitudinal gradients in Mesoamerica and South America. We combine genotyping, low coverage whole-genome sequence data, and flow cytometry to test for evidence of selection on genome size and individual repeat abundance. We find that population structure alone cannot explain the observed variation, implying that clinal patterns of genome size are maintained by natural selection. Our modeling additionally provides evidence of selection on individual heterochromatic knob repeats, likely due to their large individual contribution to genome size. To better understand the phenotypes driving selection on genome size, we conducted a growth chamber experiment using a population of highland teosinte exhibiting extensive variation in genome size. We find weak support for a positive correlation between genome size and cell size, but stronger support for a negative correlation between genome size and the rate of cell production. Reanalyzing published data of cell counts in maize shoot apical meristems, we then identify a negative correlation between cell production rate and flowering time. Together, our data suggest a model in which variation in genome size is driven by natural selection on flowering time across altitudinal clines, connecting intraspecific variation in repetitive sequence to important differences in adaptive phenotypes. PMID:29746459

Latitudinal variation in cold hardiness in introduced Tamarix and native Populus

USGS Publications Warehouse

Friedman, Jonathan M.; Roelle, James E.; Gaskin, John F.; Pepper, Alan E.; Manhart, James R.

2008-01-01

To investigate the evolution of clinal variation in an invasive plant, we compared cold hardiness in the introduced saltcedar (Tamarix ramosissima, Tamarix chinensis, and hybrids) and the native plains cottonwood (Populus deltoidessubsp. monilifera). In a shadehouse in Colorado (41°N), we grew plants collected along a latitudinal gradient in the central United States (29–48°N). On 17 occasions between September 2005 and June 2006, we determined killing temperatures using freeze-induced electrolyte leakage and direct observation. In midwinter, cottonwood survived cooling to −70°C, while saltcedar was killed at −33 to −47°C. Frost sensitivity, therefore, may limit northward expansion of saltcedar in North America. Both species demonstrated inherited latitudinal variation in cold hardiness. For example, from September through January killing temperatures for saltcedar from 29.18°N were 5–21°C higher than those for saltcedar from 47.60°N, and on September 26 and October 11, killing temperatures for cottonwood from 33.06°N were >43°C higher than those for cottonwood from 47.60°N. Analysis of nine microsatellite loci showed that southern saltcedars are more closely related to T. chinensis while northern plants are more closely related to T. ramosissima. Hybridization may have introduced the genetic variability necessary for rapid evolution of the cline in saltcedar cold hardiness.

Morphological variation and zoogeography of racers (Coluber constrictor) in the central Rocky Mountains

USGS Publications Warehouse

Corn, Paul Stephen; Bury, R. Bruce

1986-01-01

We examined 63 specimens of Coluber constrictor from Colorado and Utah using eight external morphological characters that have been used to distinguish C. c. mormon from C. c. flaviventris. We grouped the snakes into three Operational Taxonomic Units (OTU's) in a transect across the Rocky Mountains: the eastern Front Range foothills in Colorado; the inter-mountain region (western slope of Colorado and northeastern Utah); and the western foothills of the Wasatch Mountains in Utah. Statistically significant variation among the OTU's was discovered for ration of tail length to total length, number of central and subcaudal scales, and number of dentary teeth. However, variation is clinal with nearly complete overlap from one end f the transect to the other for each character, suggesting a wide zone of intergradiation in the inter-mountain region. We do not believe reported differences in reproductive parameters between Great Plains and Great Basin racers are sufficient grounds for recognition of species, because clutch size is both geographically variable and dependent on the environment. The distribution of C. constrictor is similar to that of other reptiles with transmontane distributions in the western United States, and we suggest two possible routes of dispersal across the Continental Divide in southwestern Wyoming. Thus, elevation of C. c. mormon to species status is not supported by morphological, reproductive, or zoogeographic evidence.

Inheritance of female flight in Lymantria dispar (Lepidoptera: Lymantriidae)

Treesearch

M.A. Keena; P.S. Grinberg; W.E. Wallner

2007-01-01

A clinal female fight polymorphism exists in the gypsy moth, Lymantria dispar, L., where female flight diminishes from east to west across Eurasia. A Russian population where females are capable of sustained ascending flight and a North American population with females incapable of flight were crossed: parentals, reciprocal F1,...

Divergence in the calling songs between sympatric and allopatric populations of the southern wood cricket Gryllus fultoni (Orthoptera: Gryllidae).

PubMed

Jang, Y; Gerhardt, H C

2006-03-01

In the eastern United States the wood cricket Gryllus fultoni (Orthoptera: Gryllidae) occurs in sympatry with G. vernalis in an area between eastern Kansas and west of the Appalachian Mountains. Calling songs were recorded from 13 sympatric and allopatric localities. Both field and laboratory recordings showed that chirp rate (CR) and pulse rate (PR) overlapped extensively between allopatric populations of G. fultoni and sympatric populations of G. vernalis; by contrast, there was little or no overlap in these variables between sympatric populations of these two species. Divergence in PR and CR between the two species was thus greater in areas of sympatry than in areas of allopatry. Our field and laboratory studies of G. fultoni calling songs thus demonstrate the pattern expected of character displacement and support the genetic assumptions of this hypothesis. Other possible explanations for the sympatric divergence such as ecological character displacement and clinal variation are discussed.

Local adaptation at the range peripheries of Sitka spruce.

PubMed

Mimura, M; Aitken, S N

2010-02-01

High-dispersal rates in heterogeneous environments and historical rapid range expansion can hamper local adaptation; however, we often see clinal variation in high-dispersal tree species. To understand the mechanisms of the species' distribution, we investigated local adaptation and adaptive plasticity in a range-wide context in Sitka spruce, a wind-pollinated tree species that has recently expanded its range after glaciations. Phenotypic traits were observed using growth chamber experiments that mimicked temperature and photoperiodic regimes from the limits of the species realized niche. Bud phenology exhibited parallel reaction norms among populations; however, putatively adaptive plasticity and strong divergent selection were seen in bud burst and bud set timing respectively. Natural selection appears to have favoured genotypes that maximize growth rate during available frost-free periods in each environment. We conclude that Sitka spruce has developed local adaptation and adaptive plasticity throughout its range in response to current climatic conditions despite generally high pollen flow and recent range expansion.

Taxonomic revision of Israeli snakes belonging to the Platyceps rhodorachis species complex (Reptilia: Squamata: Colubridae).

PubMed

Sinaiko, Guy; Magory-Cohen, Tali; Meiri, Shai; Dor, Roi

2018-02-15

The Platyceps rhodorachis species complex encompasses a widespread group of morphologically similar colubrid snakes. The number and identities of species from this complex in Israel have recently been debated. Studies from the previous decade concluded that there are two species in Israel and its vicinity (compared with one previously recognized), but their identity remained contested. We estimated the number of species and their taxonomic identity using morphological and molecular data. We found some evidence for clinal variation in many of the characters used to differentiate the species, and a great overlap in traits of putative species. Genetic data revealed very low sequence divergence, with all putative species being paraphyletic. Platyceps rogersi emerged as genetically closer to Platyceps saharicus rather than to its putative conspecific, P. karelini. The phylogenetic and taxonomic results thus indicate that the Israeli populations of the P. rhodorachis complex all belong to a single species, Platyceps saharicus (Schätti McCarthy 2004).

Ant Abundance along a Productivity Gradient: Addressing Two Conflicting Hypotheses

PubMed Central

Segev, Udi; Kigel, Jaime; Lubin, Yael; Tielbörger, Katja

2015-01-01

The number of individuals within a population or community and their body size can be associated with changes in resource supply. While these relationships may provide a key to better understand the role of abiotic vs. biotic constraints in animal communities, little is known about the way size and abundance of organisms change along resource gradients. Here, we studied this interplay in ants, addressing two hypotheses with opposite predictions regarding variation in population densities along resource gradients- the ‘productivity hypothesis’ and the ‘productivity-based thinning hypothesis’. The hypotheses were tested in two functional groups of ground-dwelling ants that are directly primary consumers feeding on seeds: specialized seed-eaters and generalist species. We examined variations in colony density and foraging activity (a size measurement of the forager caste) in six ant assemblages along a steep productivity gradient in a semi-arid region, where precipitation and plant biomass vary 6-fold over a distance of 250km. An increase in the density or foraging activity of ant colonies along productivity gradients is also likely to affect competitive interactions among colonies, and consequently clinal changes in competition intensity were also examined. Ant foraging activity increased with productivity for both functional groups. However, colony density revealed opposing patterns: it increased with productivity for the specialized seed-eaters, but decreased for the generalist species. Competition intensity, evaluated by spatial partitioning of species at food baits and distribution of colonies, was uncorrelated with productivity in the specialized seed-eaters, but decreased with increasing productivity in the generalists. Our results provide support for two contrasting hypotheses regarding the effect of resource availability on the abundance of colonial organisms- the ‘productivity hypothesis’ for specialized seed-eaters and the ‘productivity-based thinning hypothesis’ for generalist species. These results also stress the importance of considering the role of functional groups in studies of community structure. PMID:26176853

Ecogeography, genetics, and the evolution of human body form.

PubMed

Roseman, Charles C; Auerbach, Benjamin M

2015-01-01

Genetic resemblances among groups are non-randomly distributed in humans. This population structure may influence the correlations between traits and environmental drivers of natural selection thus complicating the interpretation of the fossil record when modern human variation is used as a referential model. In this paper, we examine the effects of population structure and natural selection on postcranial traits that reflect body size and shape with application to the more general issue of how climate - using latitude as a proxy - has influenced hominin morphological variation. We compare models that include terms reflecting population structure, ascertained from globally distributed microsatellite data, and latitude on postcranial phenotypes derived from skeletal dimensions taken from a large global sample of modern humans. We find that models with a population structure term fit better than a model of natural selection along a latitudinal cline in all cases. A model including both latitude and population structure terms is a good fit to distal limb element lengths and bi-iliac breadth, indicating that multiple evolutionary forces shaped these morphologies. In contrast, a model that included only a population structure term best explained femoral head diameter and the crural index. The results demonstrate that population structure is an important part of human postcranial variation, and that clinally distributed natural selection is not sufficient to explain among-group differentiation. The distribution of human body form is strongly influenced by the contingencies of modern human origins, which calls for new ways to approach problems in the evolution of human variation, past and present. Copyright © 2014 Elsevier Ltd. All rights reserved.

Genic Heterozygosity and Variation in Permanent Translocation Heterozygotes of the OENOTHERA BIENNIS Complex

PubMed Central

Levy, Morris; Levin, Donald A.

1975-01-01

Genic heterozygosity and variation were studied in the permanent translocation heterozygotes Oenothera biennis I, Oe. biennis II, Oe. biennis III, Oe. strigosa, Oe. parviflora I, Oe. parviflora II, and in the related bivalent formers Oe. argillicola and Oe. hookeri. From variation at 20 enzyme loci, we find that translocation heterozygosity for the entire chromosome complex is accompanied by only moderate levels of genic heterozygosity: 2.8% in Oe. strigosa, 9.5% in Oe. biennis and 14.9% in Oe. parviflora. Inbred garden strains of Oe. argillicola exhibited 8% heterozygosity; neither garden nor wild strains of Oe. hookeri displayed heterozygosity and only a single allozyme genotype was found. The mean number of alleles per locus is only 1.30 in Oe. strigosa, 1.40 in Oe. biennis, and 1.55 in Oe. parviflora, compared to 1.40 in Oe. argillicola. Clearly, the ability to accumulate and/or retain heterozygosity and variability has not been accompanied by extraordinary levels of either. Clinal variation is evident at some loci in each ring-former. A given translocation complex may vary geographically in its allozymic constitution. From gene frequencies, Oe. biennis I, II, and III, Oe. strigosa and Oe. hookeri are judged to be very closely related, whereas Oe. argillicola seems quite remote; Oe. parviflora is intermediate to the two phylads. Gene frequencies also suggest that Oe. argillicola diverged from the Euoenothera progenitor about 1,000,000 years ago, whereas most of the remaining evolution in the complex has occurred within the last 150,000 years. PMID:17248680

Genomic Evidence for Adaptive Inversion Clines in Drosophila melanogaster.

PubMed

Kapun, Martin; Fabian, Daniel K; Goudet, Jérôme; Flatt, Thomas

2016-05-01

Clines in chromosomal inversion polymorphisms-presumably driven by climatic gradients-are common but there is surprisingly little evidence for selection acting on them. Here we address this long-standing issue in Drosophila melanogaster by using diagnostic single nucleotide polymorphism (SNP) markers to estimate inversion frequencies from 28 whole-genome Pool-seq samples collected from 10 populations along the North American east coast. Inversions In(3L)P, In(3R)Mo, and In(3R)Payne showed clear latitudinal clines, and for In(2L)t, In(2R)NS, and In(3R)Payne the steepness of the clinal slopes changed between summer and fall. Consistent with an effect of seasonality on inversion frequencies, we detected small but stable seasonal fluctuations of In(2R)NS and In(3R)Payne in a temperate Pennsylvanian population over 4 years. In support of spatially varying selection, we observed that the cline in In(3R)Payne has remained stable for >40 years and that the frequencies of In(2L)t and In(3R)Payne are strongly correlated with climatic factors that vary latitudinally, independent of population structure. To test whether these patterns are adaptive, we compared the amount of genetic differentiation of inversions versus neutral SNPs and found that the clines in In(2L)t and In(3R)Payne are maintained nonneutrally and independent of admixture. We also identified numerous clinal inversion-associated SNPs, many of which exhibit parallel differentiation along the Australian cline and reside in genes known to affect fitness-related traits. Together, our results provide strong evidence that inversion clines are maintained by spatially-and perhaps also temporally-varying selection. We interpret our data in light of current hypotheses about how inversions are established and maintained. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Genetic variation in Pinus strobiformis growth and drought tolerance from southwestern US populations.

PubMed

Goodrich, Betsy A; Waring, Kristen M; Kolb, Thomas E

2016-10-01

The persistence of some tree species is threatened by combinations of novel abiotic and biotic stressors. To examine the hypothesis that Pinus strobiformis Engelm., a tree threatened by an invasive forest pathogen and a changing climate, exhibits intraspecific genetic variation in adaptive traits, we conducted a common garden study of seedlings at one location with two watering regimes using 24 populations. Four key findings emerged: (i) growth and physiological traits were low to moderately differentiated among populations but differentiation was high for some traits in water-stressed populations; (ii) seedlings from warmer climates grew larger, had higher stomatal density and were more water-use efficient (as measured by the carbon isotope ratio) than populations from colder climates; (iii) seedlings from the northern edge of the species' distribution had lower water-use efficiency, higher stomatal conductance, slower growth and longer survival in a lethal drought experiment compared with seedlings from more southern populations; and (iv) based on non-metric multidimensional scaling analyses, populations clustered into southern and northern groups, which did not correspond to current seed transfer zones. Our discovery of a clinal geographic pattern of genetic variation in adaptive traits of P. strobiformis seedlings will be useful in developing strategies to maintain the species during ongoing climate change and in the face of an invasive pathogen. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Continent-Wide Climatic Variation Drives Local Adaptation in North American White Clover.

PubMed

Wright, Sara J; Cui Zhou, Daniel; Kuhle, Amy; Olsen, Kenneth M

2017-12-21

Climate-associated clines in adaptive polymorphisms are commonly cited as evidence of local adaptation within species. However, the contribution of the clinally varying trait to overall fitness is often unknown. To address this question, we examined survival, vegetative growth, and reproductive output in a central US common garden experiment using 161 genotypes of white clover (Trifolium repens L.) originating from 15 locations across North America. White clover is polymorphic for cyanogenesis (hydrogen cyanide release upon tissue damage), a chemical defense against generalist herbivores, and climate-associated cyanogenesis clines have repeatedly evolved across the species range. Over a 12-month experiment, we observed striking correlations between the population of origin and plant performance in the common garden, with climatic distance from the common garden site predicting fitness more accurately than geographic distance. Assessments of herbivore leaf damage over the 2015 growing season indicated marginally lower herbivory on cyanogenic plants; however, this effect did not result in increased fitness in the common garden location. Linear mixed modeling suggested that while cyanogenesis variation had little predictive value for vegetative growth, it is as important as climatic variation for predicting reproductive output in the central United States. Together, our findings suggest that knowledge of climate similarity, as well as knowledge of locally favored adaptive traits, will help to inform transplantation strategies for restoration ecology and other conservation efforts in the face of climate change. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Two sources of the Russian patrilineal heritage in their Eurasian context.

PubMed

Balanovsky, Oleg; Rootsi, Siiri; Pshenichnov, Andrey; Kivisild, Toomas; Churnosov, Michail; Evseeva, Irina; Pocheshkhova, Elvira; Boldyreva, Margarita; Yankovsky, Nikolay; Balanovska, Elena; Villems, Richard

2008-01-01

Progress in the mapping of population genetic substructure provides a core source of data for the reconstruction of the demographic history of our species and for the discovery of common signals relevant to disease research: These two aspects of enquiry overlap in their empirical data content and are especially informative at continental and subcontinental levels. In the present study of the variation of the Y chromosome pool of ethnic Russians, we show that the patrilineages within the pre-Ivan the Terrible historic borders of Russia have two main distinct sources. One of these antedates the linguistic split between West and East Slavonic-speaking people and is common for the two groups; the other is genetically highlighted by the pre-eminence of haplogroup (hg) N3 and is most parsimoniously explained by extensive assimilation of (or language change in) northeastern indigenous Finno-Ugric tribes. Although hg N3 is common for both East European and Siberian Y chromosomes, other typically Siberian or Mongolian hgs (Q and C) have negligible influence within the studied Russian Y chromosome pool. The distribution of all frequent Y chromosome haplogroups (which account for 95% of the Y chromosomal spectrum in Russians) follows a similar north-south clinal pattern among autosomal markers, apparent from synthetic maps. Multidimensional scaling (MDS) plots comparing intra ethnic and interethnic variation of Y chromosome in Europe show that although well detectable, intraethnic variation signals do not cross interethnic borders, except between Poles, Ukrainians, and central-southern Russians, thereby revealing their overwhelmingly shared patrilineal ancestry.

Genetic diversity and drivers of genetic differentiation of Reaumuria soongorica of the Inner Mongolia plateau in China

Treesearch

Jiuyan Yang; Samuel A. Cushman; Xuemei Song; Jie Yang; Pujin Zhang

2015-01-01

We quantified genetic diversity and gene flow among eight populations of Reaumuria soongorica in Inner Mongolia, China. Our results showed that genetic differentiation of R. soongorica across the Inner Mongolian plateau is primarily clinal in nature and is driven primarily by differential landscape resistance across areas with changing patterns of seasonal...

Isolation by distance, resistance and/or clusters? Lessons learned from a forest-dwelling carnivore inhabiting a heterogeneous landscape

Treesearch

Aritz Ruiz-Gonzalez; Samuel A. Cushman; Maria Jose Madeira; Ettore Randi; Benjamin J. Gomez-Moliner

2015-01-01

Landscape genetics provides a valuable framework to understand how landscape features influence gene flow and to disentangle the factors that lead to discrete and/or clinal population structure. Here, we attempt to differentiate between these processes in a forest-dwelling small carnivore [European pine marten (Martes martes)]. Specifically, we used...

Northern Drosophila montana flies show variation both within and between cline populations in the critical day length evoking reproductive diapause.

PubMed

Lankinen, Pekka; Tyukmaeva, Venera I; Hoikkala, Anneli

2013-08-01

Reproductive diapause, and its correct timing, plays an important role in the life cycle of many insect species living in a seasonally varying environment at high latitudes. In the present paper we have documented variation in the critical day length (CDL) for adult reproductive diapause and the steepness of photoperiodic response curves (PPRCs) in seven clinal populations of Drosophila montana in Finland between the latitudes 61 and 67°N, paying special attention to variation in these traits within and between cline populations. The isofemale lines representing these populations showed a sharp transition from 0% to 100% in females' diapause incidence in the shortening day lengths, indicated by steep PPRCs. The mean CDL showed a clear latitudinal cline decreasing by 1.6h from North to South regardless of the age of the lines, variation within the populations (i.e. among lines) in this trait being up to 3h. The steepness of the PPRCs correlated with the age of the line and this trait showed no clear latitudinal cline. Further studies on a large number of lines from one D. montana population confirmed that while maintaining the flies in diapause preventing conditions in the laboratory has no effect on CDL, older lines had steeper PPRCs. High variation in CDL within and between D. montana cline populations is likely to be heritable and provide a good potential for the evolution of photoperiodic responses. Information on genetic variation in life-history traits, such as diapause, is of utmost importance for predicting the ability of insects to survive in seasonally changing environmental conditions and to respond to long term changes in the length of the growing period e.g. by postponing the timing of diapause towards shorter day length and later calendar date. Copyright © 2013 Elsevier Ltd. All rights reserved.

Differential foraging success across a light level spectrum explains the maintenance and spatial structure of colour morphs in a polymorphic bird.

PubMed

Tate, Gareth J; Bishop, Jacqueline M; Amar, Arjun

2016-06-01

Detectability of different colour morphs under varying light conditions has been proposed as an important driver in the maintenance of colour polymorphism via disruptive selection. To date, no studies have tested whether different morphs have selective advantages under differing light conditions. We tested this hypothesis in the black sparrowhawk, a polymorphic raptor exhibiting a discrete white and dark morph, and found that prey provisioning rates differ between the morphs depending on light condition. Dark morphs delivered more prey in lower light conditions, while white morphs provided more prey in brighter conditions. We found support for the role of breeding season light level in explaining the clinal pattern of variation in morph ratio across the species range throughout South Africa. Our results provide the first empirical evidence supporting the hypothesis that polymorphism in a species, and the spatial structuring of morphs across its distribution, may be driven by differential selective advantage via improved crypsis, under varying light conditions. © 2016 John Wiley & Sons Ltd/CNRS.

A taxonomic study of crested caracaras (Falconidae)

USGS Publications Warehouse

Dove, C.J.; Banks, R.C.

1999-01-01

The taxonomic status of the crested caracaras (Caracara spp., Falconidae) has been unsettled for many years. Current sources such as the AOU Check-list recognize a single species that includes three taxa formerly considered distinct, citing observations by Hellmayr and Conover (1949) on two specimens considered to be intermediate. We studied plumage characters and measurements of over 392 museum specimens and found no evidence of clinal change between the northern and southern continental populations. Sixteen specimens from localities near the Amazon River where these two populations sporadically meet exhibit a mosaic of plumage elements from both forms. Measurements of wing chord, bill length, and bill depth indicate that size is positively correlated with latitude north and south of the equator and that females are larger than males in the northern population. These populations do not meet in western South America. We conclude that three biological species can be identified in the crested caracaras: the insular Guadalupe Caracara (Caracara lutosus); and two continental species, Northern (C. cheriway) and Southern caracara (C. plancus), neither of which shows subspecific variation.

Inference of adult female dispersal from the distribution of gypsy moth egg masses in a Japanese city

Treesearch

A.M. Liebhold; Marek Turcani; Naoto Kamata

2008-01-01

The native range of the gypsy moth Lymantria dispar (L.) spans the temperate forests of Eurasia. Across this region, a clinal female flight polymorphism exists; gypsy moth females in eastern Asia are mostly capable of directed flight, those in western and southern Europe are largely incapable of flight and populations distributed across the centre of...

Global Transcriptional Profiling of Diapause and Climatic Adaptation in Drosophila melanogaster

PubMed Central

Zhao, Xiaqing; Bergland, Alan O.; Behrman, Emily L.; Gregory, Brian D.; Petrov, Dmitri A.; Schmidt, Paul S.

2016-01-01

Wild populations of the model organism Drosophila melanogaster experience highly heterogeneous environments over broad geographical ranges as well as over seasonal and annual timescales. Diapause is a primary adaptation to environmental heterogeneity, and in D. melanogaster the propensity to enter diapause varies predictably with latitude and season. Here we performed global transcriptomic profiling of naturally occurring variation in diapause expression elicited by short day photoperiod and moderately low temperature in two tissue types associated with neuroendocrine and endocrine signaling, heads, and ovaries. We show that diapause in D. melanogaster is an actively regulated phenotype at the transcriptional level, suggesting that diapause is not a simple physiological or reproductive quiescence. Differentially expressed genes and pathways are highly distinct in heads and ovaries, demonstrating that the diapause response is not uniform throughout the soma and suggesting that it may be comprised of functional modules associated with specific tissues. Genes downregulated in heads of diapausing flies are significantly enriched for clinally varying single nucleotide polymorphism (SNPs) and seasonally oscillating SNPs, consistent with the hypothesis that diapause is a driving phenotype of climatic adaptation. We also show that chromosome location-based coregulation of gene expression is present in the transcriptional regulation of diapause. Taken together, these results demonstrate that diapause is a complex phenotype actively regulated in multiple tissues, and support the hypothesis that natural variation in diapause propensity underlies adaptation to spatially and temporally varying selective pressures. PMID:26568616

Two Sources of the Russian Patrilineal Heritage in Their Eurasian Context

PubMed Central

Balanovsky, Oleg; Rootsi, Siiri; Pshenichnov, Andrey; Kivisild, Toomas; Churnosov, Michail; Evseeva, Irina; Pocheshkhova, Elvira; Boldyreva, Margarita; Yankovsky, Nikolay; Balanovska, Elena; Villems, Richard

2008-01-01

Progress in the mapping of population genetic substructure provides a core source of data for the reconstruction of the demographic history of our species and for the discovery of common signals relevant to disease research: These two aspects of enquiry overlap in their empirical data content and are especially informative at continental and subcontinental levels. In the present study of the variation of the Y chromosome pool of ethnic Russians, we show that the patrilineages within the pre-Ivan the Terrible historic borders of Russia have two main distinct sources. One of these antedates the linguistic split between West and East Slavonic-speaking people and is common for the two groups; the other is genetically highlighted by the pre-eminence of haplogroup (hg) N3 and is most parsimoniously explained by extensive assimilation of (or language change in) northeastern indigenous Finno-Ugric tribes. Although hg N3 is common for both East European and Siberian Y chromosomes, other typically Siberian or Mongolian hgs (Q and C) have negligible influence within the studied Russian Y chromosome pool. The distribution of all frequent Y chromosome haplogroups (which account for 95% of the Y chromosomal spectrum in Russians) follows a similar north-south clinal pattern among autosomal markers, apparent from synthetic maps. Multidimensional scaling (MDS) plots comparing intra ethnic and interethnic variation of Y chromosome in Europe show that although well detectable, intraethnic variation signals do not cross interethnic borders, except between Poles, Ukrainians, and central-southern Russians, thereby revealing their overwhelmingly shared patrilineal ancestry. PMID:18179905

Evidence that divergent selection shapes a developmental cline in a forest tree species complex.

PubMed

Costa E Silva, João; Harrison, Peter A; Wiltshire, Robert; Potts, Brad M

2018-05-19

Evolutionary change in developmental trajectories (heterochrony) is a major mechanism of adaptation in plants and animals. However, there are few detailed studies of the variation in the timing of developmental events among wild populations. We here aimed to identify the climatic drivers and measure selection shaping a genetic-based developmental cline among populations of an endemic tree species complex on the island of Tasmania. Seed lots from 38 native provenances encompassing the clinal transition from the heteroblastic Eucalyptus tenuiramis to the homoblastic Eucalyptus risdonii were grown in a common-garden field trial in southern Tasmania for 20 years. We used 27 climatic variables to model the provenance variation in vegetative juvenility as assessed at age 5 years. A phenotypic selection analysis was used to measure the fitness consequences of variation in vegetative juvenility based on its impact on the survival and reproductive capacity of survivors at age 20 years. Significant provenance divergence in vegetative juvenility was shown to be associated with home-site aridity, with the retention of juvenile foliage increasing with increasing aridity. Our results indicated that climate change may lead to different directions of selection across the geographic range of the complex, and in our mesic field site demonstrated that total directional selection within phenotypically variable provenances was in favour of reduced vegetative juvenility. We provide evidence that heteroblasty is adaptive and argue that, in assessing the impacts of rapid global change, developmental plasticity and heterochrony are underappreciated processes which can contribute to populations of long-lived organisms, such as trees, persisting and ultimately adapting to environmental change.

The Sampling Scheme Matters: Pan troglodytes troglodytes and P. t. schweinfurthii Are Characterized by Clinal Genetic Variation Rather Than a Strong Subspecies Break

PubMed Central

Fünfstück, Tillmann; Arandjelovic, Mimi; Morgan, David B.; Sanz, Crickette; Reed, Patricia; Olson, Sarah H.; Cameron, Ken; Ondzie, Alain; Peeters, Martine; Vigilant, Linda

2015-01-01

Populations of an organism living in marked geographical or evolutionary isolation from other populations of the same species are often termed subspecies and expected to show some degree of genetic distinctiveness. The common chimpanzee (Pan troglodytes) is currently described as four geographically delimited subspecies: the western (P. t. verus), the nigerian-cameroonian (P. t. ellioti), the central (P. t. troglodytes) and the eastern (P. t. schweinfurthii) chimpanzees. Although these taxa would be expected to be reciprocally monophyletic, studies have not always consistently resolved the central and eastern chimpanzee taxa. Most studies, however, used data from individuals of unknown or approximate geographic provenance. Thus, genetic data from samples of known origin may shed light on the evolutionary relationship of these subspecies. We generated microsatellite genotypes from noninvasively collected fecal samples of 185 central chimpanzees that were sampled across large parts of their range and analyzed them together with 283 published eastern chimpanzee genotypes from known localities. We observed a clear signal of isolation by distance across both subspecies. Further, we found that a large proportion of comparisons between groups taken from the same subspecies showed higher genetic differentiation than the least differentiated between-subspecies comparison. This proportion decreased substantially when we simulated a more clumped sampling scheme by including fewer groups. Our results support the general concept that the distribution of the sampled individuals can dramatically affect the inference of genetic population structure. With regard to chimpanzees, our results emphasize the close relationship of equatorial chimpanzees from central and eastern equatorial Africa and the difficult nature of subspecies definitions. PMID:25330245

The sampling scheme matters: Pan troglodytes troglodytes and P. t. schweinfurthii are characterized by clinal genetic variation rather than a strong subspecies break.

PubMed

Fünfstück, Tillmann; Arandjelovic, Mimi; Morgan, David B; Sanz, Crickette; Reed, Patricia; Olson, Sarah H; Cameron, Ken; Ondzie, Alain; Peeters, Martine; Vigilant, Linda

2015-02-01

Populations of an organism living in marked geographical or evolutionary isolation from other populations of the same species are often termed subspecies and expected to show some degree of genetic distinctiveness. The common chimpanzee (Pan troglodytes) is currently described as four geographically delimited subspecies: the western (P. t. verus), the nigerian-cameroonian (P. t. ellioti), the central (P. t. troglodytes) and the eastern (P. t. schweinfurthii) chimpanzees. Although these taxa would be expected to be reciprocally monophyletic, studies have not always consistently resolved the central and eastern chimpanzee taxa. Most studies, however, used data from individuals of unknown or approximate geographic provenance. Thus, genetic data from samples of known origin may shed light on the evolutionary relationship of these subspecies. We generated microsatellite genotypes from noninvasively collected fecal samples of 185 central chimpanzees that were sampled across large parts of their range and analyzed them together with 283 published eastern chimpanzee genotypes from known localities. We observed a clear signal of isolation by distance across both subspecies. Further, we found that a large proportion of comparisons between groups taken from the same subspecies showed higher genetic differentiation than the least differentiated between-subspecies comparison. This proportion decreased substantially when we simulated a more clumped sampling scheme by including fewer groups. Our results support the general concept that the distribution of the sampled individuals can dramatically affect the inference of genetic population structure. With regard to chimpanzees, our results emphasize the close relationship of equatorial chimpanzees from central and eastern equatorial Africa and the difficult nature of subspecies definitions. Copyright © 2014 Wiley Periodicals, Inc.

Strategies for Conserving Clinal, Ecotypic, and Disjunct Population Diversiv in Widespread Species

Treesearch

Constance I. Millar; William J. Libby

1991-01-01

Why is a chapter on widespread species appearing in a volume on rare species? One answer to that is another question: Why focus on species in the first place? Granted, species do have a unique status. They are more or less closed units genetically, and species extinction signals the end of an evolutionary lineage that may have begun millions of years ago. By contrast....

The geography of sex-specific selection, local adaptation, and sexual dimorphism.

PubMed

Connallon, Tim

2015-09-01

Local adaptation and sexual dimorphism are iconic evolutionary scenarios of intraspecific adaptive differentiation in the face of gene flow. Although theory has traditionally considered local adaptation and sexual dimorphism as conceptually distinct processes, emerging data suggest that they often act concurrently during evolutionary diversification. Here, I merge theories of local adaptation in space and sex-specific adaptation over time, and show that their confluence yields several new predictions about the roles of context-specific selection, migration, and genetic correlations, in adaptive diversification. I specifically revisit two influential predictions from classical studies of clinal adaptation and sexual dimorphism: (1) that local adaptation should decrease with distance from the species' range center and (2) that opposing directional selection between the sexes (sexual antagonism) should inevitably accompany the evolution of sexual dimorphism. I show that both predictions can break down under clinally varying selection. First, the geography of local adaptation can be sexually dimorphic, with locations of relatively high local adaptation differing profoundly between the sexes. Second, the intensity of sexual antagonism varies across the species' range, with subpopulations near the range center representing hotspots for antagonistic selection. The results highlight the context-dependent roles of migration versus sexual conflict as primary constraints to adaptive diversification. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Meta-Analysis of Mitochondrial DNA Variation in the Iberian Peninsula.

PubMed

Barral-Arca, Ruth; Pischedda, Sara; Gómez-Carballa, Alberto; Pastoriza, Ana; Mosquera-Miguel, Ana; López-Soto, Manuel; Martinón-Torres, Federico; Álvarez-Iglesias, Vanesa; Salas, Antonio

2016-01-01

The Iberian Peninsula has been the focus of attention of numerous studies dealing with mitochondrial DNA (mtDNA) variation, most of them targeting the control region segment. In the present study we sequenced the control region of 3,024 Spanish individuals from areas where available data were still limited. We also compiled mtDNA haplotypes from the literature involving 4,588 sequences and 28 population groups or small regions. We meta-analyzed all these data in order to shed further light on patterns of geographic variation, taking advantage of the large sample size and geographic coverage, in contrast with the atomized sampling strategy of previous work. The results indicate that the main mtDNA haplogroups show primarily clinal geographic patterns across the Iberian geography, roughly along a North-South axis. Haplogroup HV0 (where haplogroup U is nested) is more prevalent in the Franco Cantabrian region, in good agreement with previous findings that identified this area as a climate refuge during the Last Glacial Maximum (LGM), prior to a subsequent demographic re-expansion towards Central Europe and the Mediterranean. Typical sub-Saharan and North African lineages are slightly more prevalent in South Iberia, although at low frequencies; this pattern has been shaped mainly by the transatlantic slave trade and the Arab invasion of the Iberian Peninsula. The results also indicate that summary statistics that aim to measure molecular variation, or AMOVA, have limited sensitivity to detect population substructure, in contrast to patterns revealed by phylogeographic analysis. Overall, the results suggest that mtDNA variation in Iberia is substantially stratified. These patterns might be relevant in biomedical studies given that stratification is a common cause of false positives in case-control mtDNA association studies, and should be also considered when weighting the DNA evidence in forensic casework, which is strongly dependent on haplotype frequencies.

Meta-Analysis of Mitochondrial DNA Variation in the Iberian Peninsula

PubMed Central

Barral-Arca, Ruth; Pischedda, Sara; Gómez-Carballa, Alberto; Pastoriza, Ana; Mosquera-Miguel, Ana; López-Soto, Manuel; Martinón-Torres, Federico; Álvarez-Iglesias, Vanesa; Salas, Antonio

2016-01-01

The Iberian Peninsula has been the focus of attention of numerous studies dealing with mitochondrial DNA (mtDNA) variation, most of them targeting the control region segment. In the present study we sequenced the control region of 3,024 Spanish individuals from areas where available data were still limited. We also compiled mtDNA haplotypes from the literature involving 4,588 sequences and 28 population groups or small regions. We meta-analyzed all these data in order to shed further light on patterns of geographic variation, taking advantage of the large sample size and geographic coverage, in contrast with the atomized sampling strategy of previous work. The results indicate that the main mtDNA haplogroups show primarily clinal geographic patterns across the Iberian geography, roughly along a North-South axis. Haplogroup HV0 (where haplogroup U is nested) is more prevalent in the Franco Cantabrian region, in good agreement with previous findings that identified this area as a climate refuge during the Last Glacial Maximum (LGM), prior to a subsequent demographic re-expansion towards Central Europe and the Mediterranean. Typical sub-Saharan and North African lineages are slightly more prevalent in South Iberia, although at low frequencies; this pattern has been shaped mainly by the transatlantic slave trade and the Arab invasion of the Iberian Peninsula. The results also indicate that summary statistics that aim to measure molecular variation, or AMOVA, have limited sensitivity to detect population substructure, in contrast to patterns revealed by phylogeographic analysis. Overall, the results suggest that mtDNA variation in Iberia is substantially stratified. These patterns might be relevant in biomedical studies given that stratification is a common cause of false positives in case-control mtDNA association studies, and should be also considered when weighting the DNA evidence in forensic casework, which is strongly dependent on haplotype frequencies. PMID:27441366

Drought stress limits the geographic ranges of two tree species via different physiological mechanisms.

PubMed

Anderegg, Leander D L; HilleRisLambers, Janneke

2016-03-01

Range shifts are among the most ubiquitous ecological responses to anthropogenic climate change and have large consequences for ecosystems. Unfortunately, the ecophysiological forces that constrain range boundaries are poorly understood, making it difficult to mechanistically project range shifts. To explore the physiological mechanisms by which drought stress controls dry range boundaries in trees, we quantified elevational variation in drought tolerance and in drought avoidance-related functional traits of a widespread gymnosperm (ponderosa pine - Pinus ponderosa) and angiosperm (trembling aspen - Populus tremuloides) tree species in the southwestern USA. Specifically, we quantified tree-to-tree variation in growth, water stress (predawn and midday xylem tension), drought avoidance traits (branch conductivity, leaf/needle size, tree height, leaf area-to-sapwood area ratio), and drought tolerance traits (xylem resistance to embolism, hydraulic safety margin, wood density) at the range margins and range center of each species. Although water stress increased and growth declined strongly at lower range margins of both species, ponderosa pine and aspen showed contrasting patterns of clinal trait variation. Trembling aspen increased its drought tolerance at its dry range edge by growing stronger but more carbon dense branch and leaf tissues, implying an increased cost of growth at its range boundary. By contrast, ponderosa pine showed little elevational variation in drought-related traits but avoided drought stress at low elevations by limiting transpiration through stomatal closure, such that its dry range boundary is associated with limited carbon assimilation even in average climatic conditions. Thus, the same climatic factor (drought) may drive range boundaries through different physiological mechanisms - a result that has important implications for process-based modeling approaches to tree biogeography. Further, we show that comparing intraspecific patterns of trait variation across ranges, something rarely done in a range-limit context, helps elucidate a mechanistic understanding of range constraints. © 2015 John Wiley & Sons Ltd.

Revisiting the Iberian honey bee (Apis mellifera iberiensis) contact zone: maternal and genome-wide nuclear variations provide support for secondary contact from historical refugia.

PubMed

Chávez-Galarza, Julio; Henriques, Dora; Johnston, J Spencer; Carneiro, Miguel; Rufino, José; Patton, John C; Pinto, M Alice

2015-06-01

Dissecting diversity patterns of organisms endemic to Iberia has been truly challenging for a variety of taxa, and the Iberian honey bee is no exception. Surveys of genetic variation in the Iberian honey bee are among the most extensive for any honey bee subspecies. From these, differential and complex patterns of diversity have emerged, which have yet to be fully resolved. Here, we used a genome-wide data set of 309 neutrally tested single nucleotide polymorphisms (SNPs), scattered across the 16 honey bee chromosomes, which were genotyped in 711 haploid males. These SNPs were analysed along with an intergenic locus of the mtDNA, to reveal historical patterns of population structure across the entire range of the Iberian honey bee. Overall, patterns of population structure inferred from nuclear loci by multiple clustering approaches and geographic cline analysis were consistent with two major clusters forming a well-defined cline that bisects Iberia along a northeastern-southwestern axis, a pattern that remarkably parallels that of the mtDNA. While a mechanism of primary intergradation or isolation by distance could explain the observed clinal variation, our results are more consistent with an alternative model of secondary contact between divergent populations previously isolated in glacial refugia, as proposed for a growing list of other Iberian taxa. Despite current intense honey bee management, human-mediated processes have seemingly played a minor role in shaping Iberian honey bee genetic structure. This study highlights the complexity of the Iberian honey bee patterns and reinforces the importance of Iberia as a reservoir of Apis mellifera diversity. © 2015 John Wiley & Sons Ltd.

The Genetic Content of Chromosomal Inversions across a Wide Latitudinal Gradient

PubMed Central

Simões, Pedro; Calabria, Gemma; Picão-Osório, João; Balanyà, Joan; Pascual, Marta

2012-01-01

There is increasing evidence regarding the role of chromosomal inversions in relevant biological processes such as local adaptation and speciation. A classic example of the adaptive role of chromosomal polymorphisms is given by the clines of inversion frequencies in Drosophila subobscura, repeatable across continents. Nevertheless, not much is known about the molecular variation associated with these polymorphisms. We characterized the genetic content of ca. 600 individuals from nine European populations following a latitudinal gradient by analysing 19 microsatellite loci from two autosomes (J and U) and the sex chromosome (A), taking into account their chromosomal inversions. Our results clearly demonstrate the molecular genetic uniformity within a given chromosomal inversion across a large latitudinal gradient, particularly from Groningen (Netherlands) in the north to Málaga (Spain) in the south, experiencing highly diverse environmental conditions. This low genetic differentiation within the same gene arrangement across the nine European populations is consistent with the local adaptation hypothesis for th evolutionof chromosomal polymorphisms. We also show the effective role of chromosomal inversions in maintaining different genetic pools within these inverted genomic regions even in the presence of high gene flow. Inversions represent thus an important barrier to gene flux and can help maintain specific allelic combinations with positive effects on fitness. Consistent patterns of microsatellite allele-inversion linkage disequilibrium particularly in loci within inversions were also observed. Finally, we identified areas within inversions presenting clinal variation that might be under selection. PMID:23272126

Heritability of Two Morphological Characters within and among Natural Populations of Drosophila melanogaster

PubMed Central

Coyne, Jerry A.; Beecham, Edward

1987-01-01

Heritabilities of wing length and abdominal bristle number, as well as genetic correlations between these characters, were determined within and among populations of Drosophila melanogaster in nature. Substantial "natural" heritabilities were found when wild-caught flies from one population were compared to their laboratory-reared offspring. Natural heritabilities of bristle number approximated those derived from laboratory-raised parents and offspring, but wing length heritability was significantly lower in nature than in the laboratory. Among-population heritabilities, estimated by regressing population means of wild-caught flies against those of their laboratory-reared descendants, were close to 0.5. The genetic differentiation of populations was clinal with latitude, and was accompanied by significant geographic differences in the norms of reaction to temperature. These clines are similar to those reported on other continents and in other Drosophila species, and are almost certainly caused by natural selection. Genetic regressions between the characters reveal that the cline in bristle number may be a correlated response to geographic selection on wing length, but not vice versa. Our results indicate that there is a sizable genetic component to phenotypic variation within and among populations of D. melanogaster in nature. PMID:3123311

High Y-chromosomal diversity and low relatedness between paternal lineages on a communal scale in the Western European Low Countries during the surname establishment.

PubMed

Larmuseau, M H D; Boon, N; Vanderheyden, N; Van Geystelen, A; Larmuseau, H F M; Matthys, K; De Clercq, W; Decorte, R

2015-07-01

There is limited knowledge on the biological relatedness between citizens and on the demographical dynamics within villages, towns and cities in pre-17th century Western Europe. By combining Y-chromosomal genotypes, in-depth genealogies and surname data in a strict genetic genealogical approach, it is possible to provide insights into the genetic diversity and the relatedness between indigenous paternal lineages within a particular community at the time of the surname adoption. To obtain these insights, six Flemish communities were selected in this study based on the differences in geography and historical development. After rigorous selection of appropriate DNA donors, low relatedness between Y chromosomes of different surnames was found within each community, although there is co-occurrence of these surnames in each community since the start of the surname adoption between the 14th and 15th century. Next, the high communal diversity in Y-chromosomal lineages was comparable with the regional diversity across Flanders at that time. Moreover, clinal distributions of particular Y-chromosomal lineages between the communities were observed according to the clinal distributions earlier observed across the Flemish regions and Western Europe. No significant indication for genetic differences between communities with distinct historical development was found in the analysis. These genetic results provide relevant information for studies in historical sciences, archaeology, forensic genetics and genealogy.

High Y-chromosomal diversity and low relatedness between paternal lineages on a communal scale in the Western European Low Countries during the surname establishment

PubMed Central

Larmuseau, M H D; Boon, N; Vanderheyden, N; Van Geystelen, A; Larmuseau, H F M; Matthys, K; De Clercq, W; Decorte, R

2015-01-01

There is limited knowledge on the biological relatedness between citizens and on the demographical dynamics within villages, towns and cities in pre-17th century Western Europe. By combining Y-chromosomal genotypes, in-depth genealogies and surname data in a strict genetic genealogical approach, it is possible to provide insights into the genetic diversity and the relatedness between indigenous paternal lineages within a particular community at the time of the surname adoption. To obtain these insights, six Flemish communities were selected in this study based on the differences in geography and historical development. After rigorous selection of appropriate DNA donors, low relatedness between Y chromosomes of different surnames was found within each community, although there is co-occurrence of these surnames in each community since the start of the surname adoption between the 14th and 15th century. Next, the high communal diversity in Y-chromosomal lineages was comparable with the regional diversity across Flanders at that time. Moreover, clinal distributions of particular Y-chromosomal lineages between the communities were observed according to the clinal distributions earlier observed across the Flemish regions and Western Europe. No significant indication for genetic differences between communities with distinct historical development was found in the analysis. These genetic results provide relevant information for studies in historical sciences, archaeology, forensic genetics and genealogy. PMID:25873146

Population Genetics of the São Tomé Caecilian (Gymnophiona: Dermophiidae: Schistometopum thomense) Reveals Strong Geographic Structuring

PubMed Central

Stoelting, Ricka E.; Measey, G. John; Drewes, Robert C.

2014-01-01

Islands provide exciting opportunities for exploring ecological and evolutionary mechanisms. The oceanic island of São Tomé in the Gulf of Guinea exhibits high diversity of fauna including the endemic caecilian amphibian, Schistometopum thomense. Variation in pigmentation, morphology and size of this taxon over its c. 45 km island range is extreme, motivating a number of taxonomic, ecological, and evolutionary hypotheses to explain the observed diversity. We conducted a population genetic study of S. thomense using partial sequences of two mitochondrial DNA genes (ND4 and 16S), together with morphological examination, to address competing hypotheses of taxonomic or clinal variation. Using Bayesian phylogenetic analysis and Spatial Analysis of Molecular Variance, we found evidence of four geographic clades, whose range and approximated age (c. 253 Kya – 27 Kya) are consistent with the spread and age of recent volcanic flows. These clades explained 90% of variation in ND4 (φCT = 0.892), and diverged by 4.3% minimum pairwise distance at the deepest node. Most notably, using Mismatch Distributions and Mantel Tests, we identified a zone of population admixture that dissected the island. In the northern clade, we found evidence of recent population expansion (Fu's Fs = −13.08 and Tajima's D = −1.80) and limited dispersal (Mantel correlation coefficient = 0.36, p = 0.01). Color assignment to clades was not absolute. Paired with multinomial regression of chromatic data, our analyses suggested that the genetic groups and a latitudinal gradient together describe variation in color of S. thomense. We propose that volcanism and limited dispersal ability are the likely proximal causes of the observed genetic structure. This is the first population genetic study of any caecilian and demonstrates that these animals have deep genetic divisions over very small areas in accordance with previous speculations of low dispersal abilities. PMID:25171066

Taxonomy of Greater White-fronted Geese (Aves: Anatidae)

USGS Publications Warehouse

Banks, Richard C.

2011-01-01

Five subspecies of the Greater White-fronted Goose, Anser albifrons (Scopoli, 1769), have been named, all on the basis of wintering birds, and up to six subspecies have been recognized. There has been confusion over the application of some names, particularly in North America, because of lack of knowledge of the breeding ranges and type localities, and incorrect taxonomic decisions. There is one clinally varying subspecies in Eurasia, one that breeds in Greenland, and three in North America, one newly named herein.

Clinal differentiation and putative hybridization in a contact zone of Pinus ponderosa and P. arizonica (Pinaceae).

PubMed

Epperson, B K; Telewski, F W; Plovanich-Jones, A E; Grimes, J E

2001-06-01

The widely distributed Pinus subsection Ponderosae is a species complex that has a transition zone among taxa in the southwestern United States. In southern Arizona and New Mexico at least two recognized taxa, Pinus ponderosa var. scopulorum and Pinus arizonica or P. ponderosa var. arizonica, are known to coexist in close proximity. In this study, we report the existence of populations where the taxa are sympatric. One of the key characteristics distinguishing taxa is the number of needles per fascicle; P. ponderosa typically has three, P. arizonica has five. We examined the spatial distribution of needle-number types in a belt transect that covers a transition zone from nearly pure three-needle types at the top of Mount Lemmon to five-needle types downslope, in the Santa Catalina Mountains, Arizona. The spatial distribution is inconsistent with there being both free interbreeding among types and selective neutrality of types. Trees with intermediate types, having combinations of three, four, and five needles and/or mean numbers of needles between 3.0 and 5.0, are spatially concentrated in the middle of the transition zone. The spatial distribution supports the occurrence of hybridization and introgression, and this is consistent with reported crossabilities of the types. The results suggest that selection is acting, either on needle number per se or on other traits of the ecotype with which it may be in linkage disequilibrium, to maintain the observed steep clinal differentiation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuffey, R.J.; Pachut, J.F.

The Holocene reef-building coral Favia pallida was sampled at 4.5 m depth increments (to 40 m) from two reefs on Enewetak Atoll to examine intraspecific environmental effects. An exposed outer reef was massive and wall-like, whereas a sheltered lagoonal reef grew as a slender pinnacle. Corallite diameter and growth rate, two attributes retrievable in fossil corals, were measured with data partitioned into shallow (<20 m), intermediate (20 to 29 m), and deep-water (>29 m) subsets. Highly significant differences between depth zone populations were found for both corallite diameters and growth rates in analyses of individual and combined reef data sets.more » Canonical variates analyses (CVA) separated populations from depth zones along single, highly significant, functions. Centroids and 95% confidence intervals, calculated from CVA scores of colonies in each population, are widely separated for the lagoon reef and combined data sets. Conversely, populations from shallow and intermediate depths on the outer reef display overlapping confidence bars indicative of more gradational morphologic changes. When CV's were used to classify specimens to groups, misassignments of intermediate depth specimens to shallow or deep-water populations underscored the gradational nature of the environment. Completely intergrading populations of Favia pallida collected from different depths can be morphologically separated into statistically distinct groupings. A stratigraphic succession of such morphotypes might be interpreted as abruptly appearing separate species if sampling were not as uniform, systematic, and detailed as was possible on modern reefs. Analyses of evolutionary patterns must carefully assess potential effects of clinal variation if past evolutionary patterns are to be interpreted correctly.« less

Thermal adaptiveness of plumage color in screech owls

USGS Publications Warehouse

Mosher, James A.; Henny, Charles J.

1976-01-01

Clinal variation in the relative proportions of red and gray plum- age phases in Screech Owls (Otus asio) was analyzed by Owen (1963) and Marshall (1967). This variation was well known prior to Owen's work, but was misinterpreted (Baird, et al. 1874, Hasbrouck 1893, Allen 1893).]Laurel VanCamp and Charles Henny (MS) have 30 years of data on a northern Ohio Screech Owl population. They observed an over- winter decline (from about 25% to 15%) in the proportion of red phase birds in the winter of 1951-52. This decline was correlated with a severe winter of above normal snowfall and below average temperatures. They examined banding and recovery data and found overwinter survival of red and gray birds to be the same except for this one severe winter when 44% more red phase birds were lost than grays (VanCamp and Henny MS). Differential mortality was reported by Gullion and Marshall (1968) for red and gray phase Ruffed Grouse (Bonasa umbellus) where snow conditions for roosting is apparently the critical factor for grouse overwinter survival and is related to predation. Snow- roosting has not, to our knowledge, been observed in Screech Owls. VanCamp and Henny (MS) discuss the observations of Ruffed Grouse and Screech Owls and suggest that possible thermoregulatory differences between red and gray phase birds could account for differential overwinter survival.Our objective was to test for differences between color phase in oxygen uptake at several ambient temperatures. We hypothesized that oxygen uptake would be greater by red phase birds, especially at lower temperatures.

Adaptation and diversity along an altitudinal gradient in Ethiopian barley (Hordeum vulgare L.) landraces revealed by molecular analysis

PubMed Central

2010-01-01

Background Among the cereal crops, barley is the species with the greatest adaptability to a wide range of environments. To determine the level and structure of genetic diversity in barley (Hordeum vulgare L.) landraces from the central highlands of Ethiopia, we have examined the molecular variation at seven nuclear microsatellite loci. Results A total of 106 landrace populations were sampled in the two growing seasons (Meher and Belg; the long and short rainy seasons, respectively), across three districts (Ankober, Mojanawadera and Tarmaber), and within each district along an altitudinal gradient (from 1,798 to 3,324 m a.s.l). Overall, although significant, the divergence (e.g. FST) is very low between seasons and geographical districts, while it is high between different classes of altitude. Selection for adaptation to different altitudes appears to be the main factor that has determined the observed clinal variation, along with population-size effects. Conclusions Our data show that barley landraces from Ethiopia are constituted by highly variable local populations (farmer's fields) that have large within-population diversity. These landraces are also shown to be locally adapted, with the major driving force that has shaped their population structure being consistent with selection for adaptation along an altitudinal gradient. Overall, our study highlights the potential of such landraces as a source of useful alleles. Furthermore, these landraces also represent an ideal system to study the processes of adaptation and for the identification of genes and genomic regions that have adaptive roles in crop species. PMID:20565982

Adaptive and plastic responses of Quercus petraea populations to climate across Europe.

PubMed

Sáenz-Romero, Cuauhtémoc; Lamy, Jean-Baptiste; Ducousso, Alexis; Musch, Brigitte; Ehrenmann, François; Delzon, Sylvain; Cavers, Stephen; Chałupka, Władysław; Dağdaş, Said; Hansen, Jon Kehlet; Lee, Steve J; Liesebach, Mirko; Rau, Hans-Martin; Psomas, Achilleas; Schneck, Volker; Steiner, Wilfried; Zimmermann, Niklaus E; Kremer, Antoine

2017-07-01

How temperate forests will respond to climate change is uncertain; projections range from severe decline to increased growth. We conducted field tests of sessile oak (Quercus petraea), a widespread keystone European forest tree species, including more than 150 000 trees sourced from 116 geographically diverse populations. The tests were planted on 23 field sites in six European countries, in order to expose them to a wide range of climates, including sites reflecting future warmer and drier climates. By assessing tree height and survival, our objectives were twofold: (i) to identify the source of differential population responses to climate (genetic differentiation due to past divergent climatic selection vs. plastic responses to ongoing climate change) and (ii) to explore which climatic variables (temperature or precipitation) trigger the population responses. Tree growth and survival were modeled for contemporary climate and then projected using data from four regional climate models for years 2071-2100, using two greenhouse gas concentration trajectory scenarios each. Overall, results indicated a moderate response of tree height and survival to climate variation, with changes in dryness (either annual or during the growing season) explaining the major part of the response. While, on average, populations exhibited local adaptation, there was significant clinal population differentiation for height growth with winter temperature at the site of origin. The most moderate climate model (HIRHAM5-EC; rcp4.5) predicted minor decreases in height and survival, while the most extreme model (CCLM4-GEM2-ES; rcp8.5) predicted large decreases in survival and growth for southern and southeastern edge populations (Hungary and Turkey). Other nonmarginal populations with continental climates were predicted to be severely and negatively affected (Bercé, France), while populations at the contemporary northern limit (colder and humid maritime regions; Denmark and Norway) will probably not show large changes in growth and survival in response to climate change. © 2017 John Wiley & Sons Ltd.

Contrasting Patterns of Clinal Genetic Diversity and Potential Colonization Pathways in Two Species of Western Atlantic Fiddler Crabs.

PubMed

Laurenzano, Claudia; Costa, Tânia M; Schubart, Christoph D

2016-01-01

Fiddler crabs (Brachyura, Ocypodidae), like many other marine organisms, disperse via planktonic larvae. A lengthy pelagic larval duration is generally assumed to result in genetic connectivity even among distant populations. However, major river outflows, such as of the Amazon or Orinoco, or strong currents may act as phylogeographic barriers to ongoing gene flow. For example, the Mona Passage, located between Puerto Rico and Hispaniola, has been postulated to impair larval exchange of several species. In this study, Cox1 mtDNA data was used to analyze population genetic structure of two fiddler crab species from the western Atlantic, comparing the continental coastline and Caribbean islands. The results indicate genetic homogeneity in Minuca rapax among Atlantic (continental) populations (Suriname, Brazil), whereas Caribbean populations show significantly restricted gene flow among the constituent islands and towards continental populations. Our data support the hypothesis of the Mona Passage hindering larval exchange. Contrastingly, Caribbean Leptuca leptodactyla populations appear to be devoid of detectable variation, while Atlantic-continental (i.e. Brazilian) populations show much higher haplotype and nucleotide diversities and display slight genetic differentiation among populations within the Atlantic region, though not statistically significant. Both species show a pronounced divergence between regions, supporting the presence of a phylogeographic barrier.

Clinal patterns in genetic variation for northern leopard frog (Rana pipiens): Conservation status and population histories

USGS Publications Warehouse

Stockwell, Craig A.; Fisher, Justin D.L.; McLean, Kyle I.

2016-01-01

The security of the northern leopard frog (Rana pipiens) varies spatially with populations east and west of North Dakota considered as secure and at risk, respectively. We used genetic markers to characterize the conservation status of northern leopard frog populations across North Dakota. We used multiple regression analyses and model selection to evaluate correlations of expected heterozygosity (HE) with the direct and additive effects of: i) geographic location,ii) wetland density and iii) average annual precipitation. There was lower genetic diversity in the western portion of the state due to lower levels of diversity for populations southwest of the Missouri River. This may reflect a refugial/colonization signature for the only non-glaciated area of North Dakota. Genetic diversity was also positively associated with wetland densities which is consistent with the reliance of this species on a mosaic of wetlands. Our findings suggest that populations in the southwestern part of North Dakota are of higher conservation concern, a finding consistent with the higher risk noted for northern leopard frog populations in most states west of North Dakota. Our findings also pose the hypothesis that climate change induced changes in wetland densities will reduce genetic diversity of northern leopard frog populations.

Contrasting Patterns of Clinal Genetic Diversity and Potential Colonization Pathways in Two Species of Western Atlantic Fiddler Crabs

PubMed Central

Laurenzano, Claudia; Costa, Tânia M.; Schubart, Christoph D.

2016-01-01

Fiddler crabs (Brachyura, Ocypodidae), like many other marine organisms, disperse via planktonic larvae. A lengthy pelagic larval duration is generally assumed to result in genetic connectivity even among distant populations. However, major river outflows, such as of the Amazon or Orinoco, or strong currents may act as phylogeographic barriers to ongoing gene flow. For example, the Mona Passage, located between Puerto Rico and Hispaniola, has been postulated to impair larval exchange of several species. In this study, Cox1 mtDNA data was used to analyze population genetic structure of two fiddler crab species from the western Atlantic, comparing the continental coastline and Caribbean islands. The results indicate genetic homogeneity in Minuca rapax among Atlantic (continental) populations (Suriname, Brazil), whereas Caribbean populations show significantly restricted gene flow among the constituent islands and towards continental populations. Our data support the hypothesis of the Mona Passage hindering larval exchange. Contrastingly, Caribbean Leptuca leptodactyla populations appear to be devoid of detectable variation, while Atlantic-continental (i.e. Brazilian) populations show much higher haplotype and nucleotide diversities and display slight genetic differentiation among populations within the Atlantic region, though not statistically significant. Both species show a pronounced divergence between regions, supporting the presence of a phylogeographic barrier. PMID:27861598

Ethyl 4-(2-fur-yl)-2-oxochroman-3-carboxyl-ate.

PubMed

Prabhakar, Maddela; Reddy, J S N; Kumar, N Ravi; Ganesh, S Viswanadha; Solomon, K Anand

2010-05-12

The title compound, C(16)H(14)O(5), was prepared from the reaction of 3-carbethoxy-coumarin with furan in the presence of AlCl(3) as catalyst. In the crystal, inter-molecular C-H⋯O hydrogen-bonding inter-actions between four mol-ecules lead to a tetra-mer in the unit cell. The furan ring is anti-periplanar [C-C-C-O = 167.9 (13)°] and the ethoxy-carbonyl group is (-)anti-clinal [C-C-C-O = -128.6 (14)°] to the lactone ring.

Distribution and clinal trends of the ABO and Rh genes in select Middle Eastern countries.

PubMed

AlSuhaibani, E S; Kizilbash, N A; Afshan, K; Malik, S

2015-09-09

An understanding of the ABO and Rh blood group systems is important for blood transfusions and is also pertinent due to their potential association with certain morbidities and susceptibilities to infections. To investigate the diversity and differentiation of the ABO and Rh loci in Middle Eastern populations, data from twelve representative Middle Eastern populations were analyzed. Six populations were in conformity with Hardy-Weinberg equilibrium at the ABO locus. The pooled heterozygosity at both loci was calculated to be highest in the sample from Jordan and lowest in Bahrain. Heterogeneity was pronounced in the Northern compared to the Southern Middle Eastern populations. Overall, the absolute gene diversity was 0.0046 and gene differentiation was calculated to be 0.0100. Genetic diversity of the studied loci across all populations (HT) was estimated to be 0.4594, while the diversity within the populations (HS) was 0.4548. Nei's genetic distance analyses revealed highest affinities between the populations of Kuwait and Qatar, Oman and Yemen, and between Qatar and the United Arab Emirates. These results were displayed through a UGPMA dendrogram and principal component analyses, which established clustering of certain populations. Clinal trends of the allelic systems were observed by generating contour maps that allow a detailed appreciation of the distributions of alleles across the geography of the Arabian Peninsula and the Middle East. Taken together, these analyses are helpful in understanding the differentiation of blood group loci and for designing prospective studies for establishing the associations of these loci with health variables in the populations studied.

Pre-Quaternary divergence and subsequent radiation explain longitudinal patterns of genetic and morphological variation in the striped skink, Heremites vittatus.

PubMed

Baier, Felix; Schmitz, Andreas; Sauer-Gürth, Hedwig; Wink, Michael

2017-06-09

Many animal and plant species in the Middle East and northern Africa have a predominantly longitudinal distribution, extending from Iran and Turkey along the eastern Mediterranean coast into northern Africa. These species are potentially characterized by longitudinal patterns of biological diversity, but little is known about the underlying biogeographic mechanisms and evolutionary timescales. We examined these questions in the striped skink, Heremites vittatus, one such species with a roughly longitudinal distribution across the Middle East and northern Africa, by analyzing range-wide patterns of mitochondrial DNA (mtDNA) sequence and multi-trait morphological variation. The striped skink exhibits a basic longitudinal organization of mtDNA diversity, with three major mitochondrial lineages inhabiting northern Africa, the eastern Mediterranean coast, and Turkey/Iran. Remarkably, these lineages are of pre-Quaternary origin, and are characterized by p-distances of 9-10%. In addition, within each of these lineages a more recent Quaternary genetic diversification was observed, as evidenced by deep subclades and high haplotype diversity especially in the Turkish/Iranian and eastern Mediterranean lineages. Consistent with the genetic variation, our morphological analysis revealed that the majority of morphological traits show significant mean differences between specimens from northern Africa, the eastern Mediterranean coast, and Turkey/Iran, suggesting lineage-specific trait evolution. In addition, a subset of traits exhibits clinal variation along the eastern Mediterranean coast, potentially indicating selection gradients at the geographic transition from northern Africa to Anatolia. The existence of allopatric, morphologically and genetically divergent lineages suggests that Heremites vittatus might represent a complex with several taxa. Our work demonstrates that early divergence events in the Pliocene, likely driven by both climatic and geological factors, established the longitudinal patterns and distribution of Heremites vittatus. Subsequent radiation during the Pleistocene generated the genetic and morphological diversity observed today. Our study provides further evidence that longitudinal diversity patterns and species distributions in the Middle East and northern Africa were shaped by complex evolutionary processes, involving the region's intricate geological history, climatic oscillations, and the presence of the Sahara.

Signal variation and its morphological correlates in Paramormyrops kingsleyae provide insight into the evolution of electrogenic signal diversity in mormyrid electric fish.

PubMed

Gallant, Jason R; Arnegard, Matthew E; Sullivan, John P; Carlson, Bruce A; Hopkins, Carl D

2011-08-01

We describe patterns of geographic variation in electric signal waveforms among populations of the mormyrid electric fish species Paramormyrops kingsleyae. This analysis includes study of electric organs and electric organ discharge (EOD) signals from 553 specimens collected from 12 localities in Gabon, West-Central Africa from 1998 to 2009. We measured time, slope, and voltage values from nine defined EOD "landmarks" and determined peak spectral frequencies from each waveform; these data were subjected to principal components analysis. The majority of variation in EODs is explained by two factors: the first related to EOD duration, the second related to the magnitude of the weak head-negative pre-potential, P0. Both factors varied clinally across Gabon. EODs are shorter in eastern Gabon and longer in western Gabon. Peak P0 is slightly larger in northern Gabon and smaller in southern Gabon. P0 in the EOD is due to the presence of penetrating-stalked (Pa) electrocytes in the electric organ while absence is due to the presence of non-penetrating stalked electrocytes (NPp). Across Gabon, the majority of P. kingsleyae populations surveyed have only individuals with P0-present EODs and Pa electrocytes. We discovered two geographically distinct populations, isolated from others by barriers to migration, where all individuals have P0-absent EODs with NPp electrocytes. At two sites along a boundary between P0-absent and P0-present populations, P0-absent and P0-present individuals were found in sympatry; specimens collected there had electric organs of intermediate morphology. This pattern of geographic variation in EODs is considered in the context of current phylogenetic work. Multiple independent paedomorphic losses of penetrating stalked electrocytes have occurred within five Paramormyrops species and seven genera of mormyrids. We suggest that this key anatomical feature in EOD signal evolution may be under a simple mechanism of genetic control, and may be easily influenced by selection or drift throughout the evolutionary history of mormyrids.

Molecular and phenotypic diversity in Chionactis occipitalis (Western Shovel-nosed Snake), with emphasis on the status of C. o. klauberi (Tucson Shovel-nosed Snake).

USGS Publications Warehouse

Wood, D.A.; Meik, J.M.; Holycross, A.T.; Fisher, R.N.; Vandergast, A.G.

2008-01-01

Chionactis occipitalis (Western Shovel-nosed Snake) is a small colubrid snake inhabiting the arid regions of the Mojave, Sonoran, and Colorado deserts. Morphological assessments of taxonomy currently recognize four subspecies. However, these taxonomic proposals were largely based on weak morphological differentiation and inadequate geographic sampling. Our goal was to explore evolutionary relationships and boundaries among subspecies of C. occipitalis, with particular focus on individuals within the known range of C. o. klauberi (Tucson Shovel-nosed snake). Population sizes and range for C. o. klauberi have declined over the last 25 years due to habitat alteration and loss prompting a petition to list this subspecies as endangered. We examined the phylogeography, population structure, and subspecific taxonomy of C. occipitalis across its geographic range with genetic analysis of 1100 bases of mitochondrial DNA sequence and reanalysis of 14 morphological characters from 1543 museum specimens. We estimated the species gene phylogeny from 81 snakes using Bayesian inference and explored possible factors influencing genetic variation using landscape genetic analyses. Phylogenetic and population genetic analyses reveal genetic isolation and independent evolutionary trajectories for two primary clades. Our data indicate that diversification between these clades has developed as a result of both historical vicariance and environmental isolating mechanisms. Thus these two clades likely comprise 'evolutionary significant units' (ESUs). Neither molecular nor morphological data are concordant with the traditional C. occipitalis subspecies taxonomy. Mitochondrial sequences suggest specimens recognized as C. o. klauberi are embedded in a larger geographic clade whose range has expanded from western Arizona populations, and these data are concordant with clinal longitudinal variation in morphology. ?? 2007 Springer Science+Business Media B.V.

Genetic Adaptation vs. Ecophysiological Plasticity of Photosynthetic-Related Traits in Young Picea glauca Trees along a Regional Climatic Gradient

PubMed Central

Benomar, Lahcen; Lamhamedi, Mohammed S.; Rainville, André; Beaulieu, Jean; Bousquet, Jean; Margolis, Hank A.

2016-01-01

Assisted population migration (APM) is the intentional movement of populations within a species range to sites where future environmental conditions are projected to be more conducive to growth. APM has been proposed as a proactive adaptation strategy to maintain forest productivity and to reduce the vulnerability of forest ecosystems to projected climate change. The validity of such a strategy will depend on the adaptation capacity of populations, which can partially be evaluated by the ecophysiological response of different genetic sources along a climatic gradient. This adaptation capacity results from the compromise between (i) the degree of genetic adaptation of seed sources to their environment of origin and (ii) the phenotypic plasticity of functional trait which can make it possible for transferred seed sources to positively respond to new growing conditions. We examined phenotypic variation in morphophysiological traits of six seed sources of white spruce (Picea glauca [Moench] Voss) along a regional climatic gradient in Québec, Canada. Seedlings from the seed sources were planted at three forest sites representing a mean annual temperature (MAT) gradient of 2.2°C. During the second growing season, we measured height growth (H2014) and traits related to resources use efficiency and photosynthetic rate (Amax). All functional traits showed an adaptive response to the climatic gradient. Traits such as H2014, Amax, stomatal conductance (gs), the ratio of mesophyll to stomatal conductance, water use efficiency, and photosynthetic nitrogen-use efficiency showed significant variation in both physiological plasticity due to the planting site and seed source variation related to local genetic adaptation. However, the amplitude of seed source variation was much less than that related to plantation sites in the area investigated. The six seed sources showed a similar level of physiological plasticity. H2014, Amax and gs, but not carboxylation capacity (Vcmax), were correlated and decreased with a reduction of the average temperature of the growing season at seed origin. The clinal variation in H2014 and Amax appeared to be driven by CO2 conductance. The presence of locally adapted functional traits suggests that the use of APM may have advantages for optimizing seed source productivity in future local climates. PMID:26870067

Geographic in wing morphology relate to colonization history in New World but not Old World populations of yellow dung flies.

PubMed

Schäfer, Martin A; Berger, David; Rohner, Patrick T; Kjaersgaard, Anders; Bauerfeind, Stephanie S; Guillaume, Frédéric; Fox, Charles W; Blanckenhorn, Wolf U

2018-06-17

Geographic clines offer insights about putative targets and agents of natural selection as well as tempo and mode of adaptation. However, demographic processes can lead to clines that are indistinguishable from adaptive divergence. Using the widespread yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae), we examine quantitative genetic differentiation (Q ST ) of wing shape across North America, Europe and Japan, and compare this differentiation with that of ten microsatellites (F ST ). Morphometric analyses of 28 populations reared at three temperatures revealed significant thermal plasticity, sexual dimorphism and geographic differentiation in wing shape. In North America morphological differentiation followed the decline in microsatellite variability along the presumed route of recent colonization from the southeast to the northwest. Across Europe, where S. stercoraria presumably existed for much longer time and where no molecular pattern of isolation by distance was evident, clinal variation was less pronounced despite significant morphological differentiation (Q ST >F ST ). Shape vector comparisons further indicate that thermal plasticity (hot-to-cold) does not mirror patterns of latitudinal divergence (south-to-north), as might have been expected under a scenario with temperature as the major agent of selection. Our findings illustrate the importance of detailed phylogeographic information when interpreting geographic clines of dispersal traits in an adaptive evolutionary framework. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effects of red, far-red and blue light in maintaining growth in latitudinal populations of Norway spruce (Picea abies).

PubMed

Mølmann, Jørgen Alexander; Junttila, Olavi; Johnsen, Oystein; Olsen, Jorunn Elisabeth

2006-02-01

Seedlings of trees with a free growth pattern cease growth when night-lengths become shorter than a critical value, and this critical night-length (CNL) decreases with increasing latitude of origin. In northern populations, the light quality also appears to play an important role and a clinal variation in requirement for far-red (FR) light has been documented. In this study we dissected the light quality requirements for maintaining growth in different latitudinal populations of Norway spruce (Picea abies (L.) H. Karst.) using light emitting diodes for red (R), FR and blue (B) light, as 12 h day extension to provide 24 h photoperiod. At equal spectral photon flux, FR light was more effective than R light in maintaining growth, and the requirement of both R and FR increased with northern latitude of origin. One-to-one mixtures of R and FR light were more effective in maintaining growth than either FR or R light alone, indicating a possible interaction between R and FR light maintaining growth. Using the blue light as day extension could not prevent growth cessation in any of the populations, but delayed the bud set slightly in all populations. Our results suggest that phytochrome(s) are the primary photoreceptors in high irradiance responses maintaining growth in Norway spruce seedlings.

Human impact in naturally patched small populations: genetic structure and conservation of the burrowing rodent, tuco-tuco (Ctenomys lami).

PubMed

Lopes, Carla M; de Freitas, Thales R O

2012-01-01

Isolated or semi-isolated small populations are commonly found among species, due to a naturally patchy occupancy of suitable habitats or also as a result of habitat alterations. These populations are subject to an increased risk of local extinction because they are more vulnerable to demographic, genetic, and environmental stochasticity. Considering that natural areas have been becoming progressively more fragmented and smaller, understanding the genetic structure and evolutionary dynamics of small populations is critical. Ctenomys lami has 26 karyotypes distributed in a small area (936 km(2)) continually modified by human actions. We assessed the genetic geographical structure of this species, examining 178 specimens sampled on a fine scale, using information from chromosomal variability, mitochondrial DNA control region and cytochrome c oxidase subunit I sequences, and 14 microsatellite loci. The observed isolation-by-distance pattern and a clinal genetic variation suggest a stepping-stone population model. The results did not indicate genetic structuring associated with distinct karyotypes. However, mitochondrial and nuclear molecular markers demonstrated the existence of 2 demes, which are not completely isolated but are probably reinforced by a geographical barrier. The vulnerability of C. lami is greater than previously supposed, and our data support the designation of one Evolutionary Significant Unit and one Management Unit, and also the inclusion of this species' conservation status as vulnerable.

Changes during the holocene in the size of white-tailed deer ( Odocoileus virginianus) from central Illinois

NASA Astrophysics Data System (ADS)

Purdue, James R.

1989-11-01

White-tailed deer ( Odocoileus virginianus) from central Illinois varied in size during the Holocene. The record, which extends back to 8450 yr B.P., indicates small deer through the mid-Holocene until 3650 yr B.P., after which size increases. Although influences of winter climate, seasonality, anthropogenic effects, and other ecological factors should not be discounted, an intriguing possible cause of the deer size shifts is insolation-driven summer climate and its influence on food resources. In the Holocene, small deer size is correlated with high summer insolation and with low winter insolation. Climatic models indicate that in spite of changes in insolation, Holocene winters did not vary greatly through time, especially in contrast to summers, which were dynamic. Physiological constraints peculiar to O. virginianus make critical the quality of summer forage for determining final adult size. Summer temperature averaged 2°C warmer than present during the middle Holocene, which increased evaporation and probably reduced the period of availability of high-quality forage low in fiber and high in protein. Consequently, less fuel for growth was consumed by mid-Holocene deer and only small body size was achieved. Other possible causes (e.g., Bergmann's rule, seasonality) of clinal variation are considered with reference to central Illinois deer, but at present the most parsimonious explanation appears to be the summer insolation hypothesis.

Adaptive dynamics of cuticular hydrocarbons in Drosophila

PubMed Central

Rajpurohit, Subhash; Hanus, Robert; Vrkoslav, Vladimír; Behrman, Emily L.; Bergland, Alan O.; Petrov, Dmitri; Cvačka, Josef; Schmidt, Paul S.

2016-01-01

Cuticular hydrocarbons (CHCs) are hydrophobic compounds deposited on the arthropod cuticle that are of functional significance with respect to stress tolerance, social interactions, and mating dynamics. We characterized CHC profiles in natural populations of Drosophila melanogaster at five levels: across a latitudinal transect in the eastern U.S., as a function of developmental temperature during culture, across seasonal time in replicate years, and as a function of rapid evolution in experimental mesocosms in the field. Furthermore, we also characterized spatial and temporal change in allele frequencies for SNPs in genes that are associated with the production and chemical profile of CHCs. Our data demonstrate a striking degree of parallelism for clinal and seasonal variation in CHCs in this taxon; CHC profiles also demonstrate significant plasticity in response to rearing temperature, and the observed patterns of plasticity parallel the spatiotemporal patterns observed in nature. We find that these congruent shifts in CHC profiles across time and space are also mirrored by predictable shifts in allele frequencies at SNPs associated with CHC chain length. Finally, we observed rapid and predictable evolution of CHC profiles in experimental mesocosms in the field. Together, these data strongly suggest that CHC profiles respond rapidly and adaptively to environmental parameters that covary with latitude and season, and that this response reflects the process of local adaptation in natural populations of D. melanogaster. PMID:27718537

Genome-wide comparisons reveal a clinal species pattern within a holobenthic octopod-the Australian Southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae).

PubMed

Morse, Peter; Kjeldsen, Shannon R; Meekan, Mark G; Mccormick, Mark I; Finn, Julian K; Huffard, Christine L; Zenger, Kyall R

2018-02-01

The southern blue-ringed octopus, Hapalochlaena maculosa (Hoyle, 1883) lacks a planktonic dispersal phase, yet ranges across Australia's southern coastline. This species' brief and holobenthic life history suggests gene flow might be limited, leaving distant populations prone to strong genetic divergence. This study used 17,523 genome-wide SNP loci to investigate genetic structuring and local adaptation patterns of H. maculosa among eight sampling sites along its reported range. Within sites, interrelatedness was very high, consistent with the limited dispersal of this taxon. However, inbreeding coefficients were proportionally lower among sites where substructuring was not detected, suggesting H. maculosa might possess a mechanism for inbreeding avoidance. Genetic divergence was extremely high among all sites, with the greatest divergence observed between both ends of the distribution, Fremantle, WA, and Stanley, TAS. Genetic distances closely followed an isolation by geographic distance pattern. Outlier analyses revealed distinct selection signatures at all sites, with the strongest divergence reported between Fremantle and the other Western Australian sites. Phylogenetic reconstructions using the described sister taxon H. fasciata (Hoyle, 1886) further supported that the genetic divergence between distal H. maculosa sites in this study was equivalent to that of between established heterospecifics within this genus. However, it is advocated that taxonomic delineations within this species should be made with caution. These data indicate that H. maculosa forms a clinal species pattern across its geographic range, with gene flow present through allele sharing between adjacent populations. Morphological investigations are recommended for a robust resolution of the taxonomic identity and ecotype boundaries of this species.

Using mitochondrial DNA to test the hypothesis of a European post-glacial human recolonization from the Franco-Cantabrian refuge.

PubMed

García, O; Fregel, R; Larruga, J M; Álvarez, V; Yurrebaso, I; Cabrera, V M; González, A M

2011-01-01

It has been proposed that the distribution patterns and coalescence ages found in Europeans for mitochondrial DNA (mtDNA) haplogroups V, H1 and H3 are the result of a post-glacial expansion from a Franco-Cantabrian refuge that recolonized central and northern areas. In contrast, in this refined mtDNA study of the Cantabrian Cornice that contributes 413 partial and 9 complete new mtDNA sequences, including a large Basque sample and a sample of Asturians, no experimental evidence was found to support the human refuge-expansion theory. In fact, all measures of gene diversity point to the Cantabrian Cornice in general and the Basques in particular, as less polymorphic for V, H1 and H3 than other southern regions in Iberia or in Central Europe. Genetic distances show the Cantabrian Cornice is a very heterogeneous region with significant local differences. The analysis of several minor subhaplogroups, based on complete sequences, also suggests different focal expansions over a local and peninsular range that did not affect continental Europe. Furthermore, all detected clinal trends show stronger longitudinal than latitudinal profiles. In Northern Iberia, it seems that the highest diversity values for some haplogroups with Mesolithic coalescence ages are centred on the Mediterranean side, including Catalonia and South-eastern France.

Population genetic structure of the blue-fronted Amazon (Amazona aestiva, Psittacidae: Aves) based on nuclear microsatellite loci: implications for conservation.

PubMed

Leite, K C E; Seixas, G H F; Berkunsky, I; Collevatti, R G; Caparroz, R

2008-09-09

The blue-fronted Amazon (Amazona aestiva) is a widely distributed Neotropical parrot and one of the most captured parrots in nature to supply the illegal trade of wild animals. The objectives of the present study were to analyze the genetic structure of A. aestiva to identify management units and support conservation planning and to verified if A. aestiva populations have undergone a recent bottleneck due to habitat loss and capture for the pet trade. The genetic structure was accessed by analyzing six microsatellite loci in 74 individuals of A. aestiva, including samples from the two subspecies (A. a. aestiva and A. a. xanthopteryx), from five populations: four in Brazil and one in Argentina. A significant genetic differentiation (theta = 0.007, p = 0.005) could be detected only between the most distant populations, Tocantins and Argentina, localized at the northeast and southwest limits of the sample sites, respectively. There was no evidence of inbreeding within or between populations, suggesting random mating among individuals. These results suggest a clinal distribution of genetic variability, as observed for variation in plumage color of the two A. aestiva subspecies. Bottleneck analysis did not show a recent reduction in population size. Thus, for the management and conservation of the species, the populations from Argentina and Tocantins should be considered as different management units, and the other populations from the center of the geographical distribution as another management unit.

Clinal variation in the juvenal plumage of American kestrels

USGS Publications Warehouse

Smallwood, J.A.; Natale, C.; Steenhof, K.; Meetz, M.; Marti, C.D.; Melvin, R.J.; Bortolotti, G.R.; Robertson, R.; Robertson, S.; Shuford, W.R.; Lindemann, S.A.; Tornwall, B.

1999-01-01

The American Kestrel(Falco sparverius) is a sexually dichromatic falcon that exhibits considerable individual plumage variability. For example, the anterior extent of the black dorsal barring in juvenile males has been used throughout North America as one of several aging criteria, but recent data demonstrate that the variability among individual Southeastern American Kestrels(E S. paulus)exceeds that accounted for by age. The objective of this study was to search for geographic patterns in the variability of juvenal plumage, particularly those characteristics considered indicative of age. Nestling kestrels (n = 610) were examined prior to fledging during the 1997 breeding season at nest box programs across a large portion of the North American breeding range. From south to north (1) the crown patches of both males and females become more completely rufous, and (2) shaft streaks on forehead and crown feathers become more pronounced, especially in males. Male Southeastern American Kestrels differed from other males (E s. sparverius) in that the anterior extent of dorsal barring averaged less but was more variable. The variability observed in North America appears to be part of a cline extending across the species range in the Western Hemisphere, where tropical subspecies are small and have reduced dorsal barring. Both body size and, especially in males, dorsal barring increases with increasing north and south latitude. We suggest that this geographic pattern is adaptive in terms of thermoregulation, and that differences in the sex roles may explain why males become less barred with maturity while females do not.

Genetic architecture and genomic patterns of gene flow between hybridizing species of Picea

PubMed Central

De La Torre, A; Ingvarsson, P K; Aitken, S N

2015-01-01

Hybrid zones provide an opportunity to study the effects of selection and gene flow in natural settings. We employed nuclear microsatellites (single sequence repeat (SSR)) and candidate gene single-nucleotide polymorphism markers (SNPs) to characterize the genetic architecture and patterns of interspecific gene flow in the Picea glauca × P. engelmannii hybrid zone across a broad latitudinal (40–60 degrees) and elevational (350–3500 m) range in western North America. Our results revealed a wide and complex hybrid zone with broad ancestry levels and low interspecific heterozygosity, shaped by asymmetric advanced-generation introgression, and low reproductive barriers between parental species. The clinal variation based on geographic variables, lack of concordance in clines among loci and the width of the hybrid zone points towards the maintenance of species integrity through environmental selection. Congruency between geographic and genomic clines suggests that loci with narrow clines are under strong selection, favoring either one parental species (directional selection) or their hybrids (overdominance) as a result of strong associations with climatic variables such as precipitation as snow and mean annual temperature. Cline movement due to past demographic events (evidenced by allelic richness and heterozygosity shifts from the average cline center) may explain the asymmetry in introgression and predominance of P. engelmannii found in this study. These results provide insights into the genetic architecture and fine-scale patterns of admixture, and identify loci that may be involved in reproductive barriers between the species. PMID:25806545

Genetic heterogeneity underlying variation in a locally adaptive clinal trait in Pinus sylvestris revealed by a Bayesian multipopulation analysis.

PubMed

Kujala, S T; Knürr, T; Kärkkäinen, K; Neale, D B; Sillanpää, M J; Savolainen, O

2017-05-01

Local adaptation is a common feature of plant and animal populations. Adaptive phenotypic traits are genetically differentiated along environmental gradients, but the genetic basis of such adaptation is still poorly known. Genetic association studies of local adaptation combine data over populations. Correcting for population structure in these studies can be problematic since both selection and neutral demographic events can create similar allele frequency differences between populations. Correcting for demography with traditional methods may lead to eliminating some true associations. We developed a new Bayesian approach for identifying the loci underlying an adaptive trait in a multipopulation situation in the presence of possible double confounding due to population stratification and adaptation. With this method we studied the genetic basis of timing of bud set, a surrogate trait for timing of yearly growth cessation that confers local adaptation to the populations of Scots pine (Pinus sylvestris). Population means of timing of bud set were highly correlated with latitude. Most effects at individual loci were small. Interestingly, we found genetic heterogeneity (that is, different sets of loci associated with the trait) between the northern and central European parts of the cline. We also found indications of stronger stabilizing selection toward the northern part of the range. The harsh northern conditions may impose greater selective pressure on timing of growth cessation, and the relative importance of different environmental cues used for tracking the seasons might differ depending on latitude of origin.

The origin, global distribution, and functional impact of the human 8p23 inversion polymorphism.

PubMed

Salm, Maximilian P A; Horswell, Stuart D; Hutchison, Claire E; Speedy, Helen E; Yang, Xia; Liang, Liming; Schadt, Eric E; Cookson, William O; Wierzbicki, Anthony S; Naoumova, Rossi P; Shoulders, Carol C

2012-06-01

Genomic inversions are an increasingly recognized source of genetic variation. However, a lack of reliable high-throughput genotyping assays for these structures has precluded a full understanding of an inversion's phylogenetic, phenotypic, and population genetic properties. We characterize these properties for one of the largest polymorphic inversions in man (the ∼4.5-Mb 8p23.1 inversion), a structure that encompasses numerous signals of natural selection and disease association. We developed and validated a flexible bioinformatics tool that utilizes SNP data to enable accurate, high-throughput genotyping of the 8p23.1 inversion. This tool was applied retrospectively to diverse genome-wide data sets, revealing significant population stratification that largely follows a clinal "serial founder effect" distribution model. Phylogenetic analyses establish the inversion's ancestral origin within the Homo lineage, indicating that 8p23.1 inversion has occurred independently in the Pan lineage. The human inversion breakpoint was localized to an inverted pair of human endogenous retrovirus elements within the large, flanking low-copy repeats; experimental validation of this breakpoint confirmed these elements as the likely intermediary substrates that sponsored inversion formation. In five data sets, mRNA levels of disease-associated genes were robustly associated with inversion genotype. Moreover, a haplotype associated with systemic lupus erythematosus was restricted to the derived inversion state. We conclude that the 8p23.1 inversion is an evolutionarily dynamic structure that can now be accommodated into the understanding of human genetic and phenotypic diversity.

The origin, global distribution, and functional impact of the human 8p23 inversion polymorphism

PubMed Central

Salm, Maximilian P.A.; Horswell, Stuart D.; Hutchison, Claire E.; Speedy, Helen E.; Yang, Xia; Liang, Liming; Schadt, Eric E.; Cookson, William O.; Wierzbicki, Anthony S.; Naoumova, Rossi P.; Shoulders, Carol C.

2012-01-01

Genomic inversions are an increasingly recognized source of genetic variation. However, a lack of reliable high-throughput genotyping assays for these structures has precluded a full understanding of an inversion's phylogenetic, phenotypic, and population genetic properties. We characterize these properties for one of the largest polymorphic inversions in man (the ∼4.5-Mb 8p23.1 inversion), a structure that encompasses numerous signals of natural selection and disease association. We developed and validated a flexible bioinformatics tool that utilizes SNP data to enable accurate, high-throughput genotyping of the 8p23.1 inversion. This tool was applied retrospectively to diverse genome-wide data sets, revealing significant population stratification that largely follows a clinal “serial founder effect” distribution model. Phylogenetic analyses establish the inversion's ancestral origin within the Homo lineage, indicating that 8p23.1 inversion has occurred independently in the Pan lineage. The human inversion breakpoint was localized to an inverted pair of human endogenous retrovirus elements within the large, flanking low-copy repeats; experimental validation of this breakpoint confirmed these elements as the likely intermediary substrates that sponsored inversion formation. In five data sets, mRNA levels of disease-associated genes were robustly associated with inversion genotype. Moreover, a haplotype associated with systemic lupus erythematosus was restricted to the derived inversion state. We conclude that the 8p23.1 inversion is an evolutionarily dynamic structure that can now be accommodated into the understanding of human genetic and phenotypic diversity. PMID:22399572

Sex-specific divergence for adaptations to dehydration stress in Drosophila kikkawai.

PubMed

Parkash, Ravi; Ranga, Poonam

2013-09-01

Several studies on diverse Drosophila species have reported higher desiccation resistance of females, but the physiological basis of such sex-specific differences has received less attention. We tested whether sex-specific differences in cuticular traits (melanic females and non-melanic males) of Drosophila kikkawai correspond with divergence in their water balance mechanisms. Our results are interesting in several respects. First, positive clinal variation in desiccation resistance was correlated with cuticular melanisation in females but with changes in cuticular lipid mass in males, despite a lack of differences between the sexes for the rate of water loss. Second, a comparative analysis of water budget showed that females of the northern population stored more body water as well as hemolymph content and exhibited greater dehydration tolerance than flies from the southern tropics. In contrast, we found no geographical variation in the males for water content and dehydration tolerance. Third, an ~10-fold increase in the rate of water loss after organic solvent treatment of male D. kikkawai suggested a role of cuticular lipids in cuticular transpiration, but had no effect in the females. Fourth, geographical differences in the storage of carbohydrate content (metabolic fuel) were observed in females but not in males. Interestingly, in females, the rate of utilization of carbohydrates did not vary geographically, but males from drier localities showed a 50% reduction compared with wetter localities. Thus, body melanisation, increased body water, hemolymph, carbohydrate content and greater dehydration tolerance confer greater desiccation resistance in females, but a reduced rate of water loss is the only possible mechanism to cope with drought stress in males. Finally, acclimated females showed a significant increase in drought resistance associated with higher trehalose content as well as dehydration tolerance, while males showed no acclimation response. Thus, sex-specific differences in desiccation resistance of D. kikkawai are associated with divergence in some water balance strategies, despite a lack of differences in the rate of water loss between the two sexes.

Local adaptations and climate change: converging sensitivity of bud break in black spruce provenances.

PubMed

Rossi, Sergio

2015-07-01

Species with transcontinental distribution or spread over wide geographical regions develop populations with growth traits genetically adapted to the local climate. The aim of this study was to investigate the ecotypic sensitivity of bud break, a strong adaptive trait, to a changing environment. Six phenological phases of bud break were monitored daily on black spruce [Picea mariana (Mill.) BSP] seedlings submitted to different temperatures (12, 16 and 20 °C) and photoperiods (14, 18 and 22 h). Six provenances were tested in growth chambers, produced from seeds collected along the whole latitudinal range of the closed boreal forest in Quebec, Canada. Bud break lasted 13.3 days on average and occurred earlier in seedlings from colder sites. The annual temperature of the sites suitably tracked the clinal variation among ecotypes, providing a clear biological explanation for the environmental signal driving the adaptive divergence of populations to the local climate. Increasing temperature induced an earlier bud break according to a non-linear pattern with greater advancements observed between 12 and 16 °C. Photoperiod was significant, but sensitivity analysis indicated that its effect on bud break was marginal with respect to temperature. No interaction of provenance × treatment was observed, demonstrating an ecotypic convergence of the responses to both factors. Changes in the growing conditions could substantially modify the synchronization between bud phenology and climate, thus exposing the developing meristems of black spruce to frost damage. However, similar advancements of bud break could be expected in the different ecotypes subjected to warmer temperatures or longer day lengths.

A craniometric study of the black and white Colobus Illiger 1811 (Primates: Ceropithecoidea).

PubMed

Hull, D B

1979-08-01

This study examines the craniometry of Black and White Colobus monkeys using 1072 specimens representing all the recognized subspecies (after Rahm, '70) of the genus. Seventy-six measurements were taken on each individual, and examined using canonical variates analysis and clustering by Ward's Error Sum method. The assumptions of the analytical techniques are shown to be met, and the results demonstrated to be stable. Examination of the populations for statistical difference and taxonomic distinctiveness using a multivariate extension of Mayr's Rule indicates that the taxonomy presented by Rahm ('70) is essentially correct, except that the subspecies of guereza across the northern part of Central Africa should be lumped into a single group--C. g. occidentalis--and the subspecies of montane angolan colobus in Eastern Zaire should all be lumped into C. a. ruwenzorii. The systematic patterns of the genus illustrate the whole range of the process of speciation, from barely distinct subspecies, to subspecies almost as distinct as allopatric species of the genus, and on the fully sympatric species Three major zoogeographic areas may be delineated: an East African area dominated by the effects of the Rift Valley, with a large number of subspecies isolated in forest islands; a Central African area with little subspeciation and sympatric overlap of the major species of Colobus; and a West African area with a clinal pattern of distribution of subspecies, and secondary intergradation. The arbitrary nature of Mary's Rule is also apparent. Lastly, the CVA indicated major differences across the genus to be located in the teeth and jaws, suggesting diet might be an important distinguishing feature in Colobus.

Spatially Explicit Models to Investigate Geographic Patterns in the Distribution of Forensic STRs: Application to the North-Eastern Mediterranean.

PubMed

Messina, Francesco; Finocchio, Andrea; Akar, Nejat; Loutradis, Aphrodite; Michalodimitrakis, Emmanuel I; Brdicka, Radim; Jodice, Carla; Novelletto, Andrea

2016-01-01

Human forensic STRs used for individual identification have been reported to have little power for inter-population analyses. Several methods have been developed which incorporate information on the spatial distribution of individuals to arrive at a description of the arrangement of diversity. We genotyped at 16 forensic STRs a large population sample obtained from many locations in Italy, Greece and Turkey, i.e. three countries crucial to the understanding of discontinuities at the European/Asian junction and the genetic legacy of ancient migrations, but seldom represented together in previous studies. Using spatial PCA on the full dataset, we detected patterns of population affinities in the area. Additionally, we devised objective criteria to reduce the overall complexity into reduced datasets. Independent spatially explicit methods applied to these latter datasets converged in showing that the extraction of information on long- to medium-range geographical trends and structuring from the overall diversity is possible. All analyses returned the picture of a background clinal variation, with regional discontinuities captured by each of the reduced datasets. Several aspects of our results are confirmed on external STR datasets and replicate those of genome-wide SNP typings. High levels of gene flow were inferred within the main continental areas by coalescent simulations. These results are promising from a microevolutionary perspective, in view of the fast pace at which forensic data are being accumulated for many locales. It is foreseeable that this will allow the exploitation of an invaluable genotypic resource, assembled for other (forensic) purposes, to clarify important aspects in the formation of local gene pools.

Rethinking refugia: Tree topology, divergence dates, and demographic history trace the distribution of the endangered Plymouth gentian (Sabatia kennedyana) from the Pleistocene glaciation to present day.

PubMed

Suarez-Gonzalez, Adriana; Sutton, Jolene T; Trant, Andrew J; Zamlynny, Elena; Good, Sara V

2015-04-01

Molecular population genetics is a powerful tool to infer how species responded to past environmental change. In the northern hemisphere, interest is increasing in how species responded to changes in ice coverage and temperature during the last glaciation maximum (LGM, between 18000-21000 yr ago) with a common assumption that glacial refugia were located at the southern edge of a species range. We reconstructed the glacial and postglacial phylogeography of Sabatia kennedyana, a member of the Atlantic Coastal Plains Flora with a current distribution from Nova Scotia (NS) to South Carolina, using both cpDNA and nuclear markers. We also examined clinal variation in morphological traits, in particular relative investment in asexual vs sexual growth. We find strong evidence that the species did not reside in southern glacial refugia, but rather in primary glacial refugia off the exposed continental shelf extending from Cape Cod and that this area was responsible for the founding of modern populations across the range from Nova Scotia (NS) to the United States. Additionally, based on the finding of higher cpDNA diversity and older cpDNA lineages in NS, we propose that multiple founder events occurred in NS, while only a single lineage gave rise to current populations in the United States. By understanding how S. kennedyana responded to past shifts in climate and by identifying areas of high genetic diversity in the northern range edge, we discuss the potential response of the species to future climate change scenarios. © 2015 Botanical Society of America, Inc.

Complex Patterns of Local Adaptation in Teosinte

PubMed Central

Pyhäjärvi, Tanja; Hufford, Matthew B.; Mezmouk, Sofiane; Ross-Ibarra, Jeffrey

2013-01-01

Populations of widely distributed species encounter and must adapt to local environmental conditions. However, comprehensive characterization of the genetic basis of adaptation is demanding, requiring genome-wide genotype data, multiple sampled populations, and an understanding of population structure and potential selection pressures. Here, we used single-nucleotide polymorphism genotyping and data on numerous environmental variables to describe the genetic basis of local adaptation in 21 populations of teosinte, the wild ancestor of maize. We found complex hierarchical genetic structure created by altitude, dispersal events, and admixture among subspecies, which complicated identification of locally beneficial alleles. Patterns of linkage disequilibrium revealed four large putative inversion polymorphisms showing clinal patterns of frequency. Population differentiation and environmental correlations suggest that both inversions and intergenic polymorphisms are involved in local adaptation. PMID:23902747

Genetic variation affecting host-parasite interactions: different genes affect different aspects of sigma virus replication and transmission in Drosophila melanogaster.

PubMed

Bangham, Jenny; Kim, Kang-Wook; Webster, Claire L; Jiggins, Francis M

2008-04-01

In natural populations, genetic variation affects resistance to disease. Knowing how much variation exists, and understanding the genetic architecture of this variation, is important for medicine, for agriculture, and for understanding evolutionary processes. To investigate the extent and nature of genetic variation affecting resistance to pathogens, we are studying a tractable model system: Drosophila melanogaster and its natural pathogen the vertically transmitted sigma virus. We show that considerable genetic variation affects transmission of the virus from parent to offspring. However, maternal and paternal transmission of the virus is affected by different genes. Maternal transmission is a simple Mendelian trait: most of the genetic variation is explained by a polymorphism in ref(2)P, a gene already well known to affect resistance to sigma. In contrast, there is considerable genetic variation in paternal transmission that cannot be explained by ref(2)P and is caused by other loci on chromosome 2. Furthermore, we found no genetic correlation between paternal transmission of the virus and resistance to infection by the sigma virus following injection. This suggests that different loci affect viral replication and paternal transmission.

Uniparental Markers of Contemporary Italian Population Reveals Details on Its Pre-Roman Heritage

PubMed Central

Álvarez-Iglesias, Vanesa; Fondevila, Manuel; Blanco-Verea, Alejandro; Carracedo, Ángel; Pascali, Vincenzo L.; Capelli, Cristian

2012-01-01

Background According to archaeological records and historical documentation, Italy has been a melting point for populations of different geographical and ethnic matrices. Although Italy has been a favorite subject for numerous population genetic studies, genetic patterns have never been analyzed comprehensively, including uniparental and autosomal markers throughout the country. Methods/Principal Findings A total of 583 individuals were sampled from across the Italian Peninsula, from ten distant (if homogeneous by language) ethnic communities — and from two linguistic isolates (Ladins, Grecani Salentini). All samples were first typed for the mitochondrial DNA (mtDNA) control region and selected coding region SNPs (mtSNPs). This data was pooled for analysis with 3,778 mtDNA control-region profiles collected from the literature. Secondly, a set of Y-chromosome SNPs and STRs were also analyzed in 479 individuals together with a panel of autosomal ancestry informative markers (AIMs) from 441 samples. The resulting genetic record reveals clines of genetic frequencies laid according to the latitude slant along continental Italy – probably generated by demographical events dating back to the Neolithic. The Ladins showed distinctive, if more recent structure. The Neolithic contribution was estimated for the Y-chromosome as 14.5% and for mtDNA as 10.5%. Y-chromosome data showed larger differentiation between North, Center and South than mtDNA. AIMs detected a minor sub-Saharan component; this is however higher than for other European non-Mediterranean populations. The same signal of sub-Saharan heritage was also evident in uniparental markers. Conclusions/Significance Italy shows patterns of molecular variation mirroring other European countries, although some heterogeneity exists based on different analysis and molecular markers. From North to South, Italy shows clinal patterns that were most likely modulated during Neolithic times. PMID:23251386

Spatially Explicit Models to Investigate Geographic Patterns in the Distribution of Forensic STRs: Application to the North-Eastern Mediterranean

PubMed Central

Messina, Francesco; Finocchio, Andrea; Akar, Nejat; Loutradis, Aphrodite; Michalodimitrakis, Emmanuel I.; Brdicka, Radim; Jodice, Carla

2016-01-01

Human forensic STRs used for individual identification have been reported to have little power for inter-population analyses. Several methods have been developed which incorporate information on the spatial distribution of individuals to arrive at a description of the arrangement of diversity. We genotyped at 16 forensic STRs a large population sample obtained from many locations in Italy, Greece and Turkey, i.e. three countries crucial to the understanding of discontinuities at the European/Asian junction and the genetic legacy of ancient migrations, but seldom represented together in previous studies. Using spatial PCA on the full dataset, we detected patterns of population affinities in the area. Additionally, we devised objective criteria to reduce the overall complexity into reduced datasets. Independent spatially explicit methods applied to these latter datasets converged in showing that the extraction of information on long- to medium-range geographical trends and structuring from the overall diversity is possible. All analyses returned the picture of a background clinal variation, with regional discontinuities captured by each of the reduced datasets. Several aspects of our results are confirmed on external STR datasets and replicate those of genome-wide SNP typings. High levels of gene flow were inferred within the main continental areas by coalescent simulations. These results are promising from a microevolutionary perspective, in view of the fast pace at which forensic data are being accumulated for many locales. It is foreseeable that this will allow the exploitation of an invaluable genotypic resource, assembled for other (forensic) purposes, to clarify important aspects in the formation of local gene pools. PMID:27898725

Contemporary paternal genetic landscape of Polish and German populations: from early medieval Slavic expansion to post-World War II resettlements.

PubMed

Rębała, Krzysztof; Martínez-Cruz, Begoña; Tönjes, Anke; Kovacs, Peter; Stumvoll, Michael; Lindner, Iris; Büttner, Andreas; Wichmann, H-Erich; Siváková, Daniela; Soták, Miroslav; Quintana-Murci, Lluís; Szczerkowska, Zofia; Comas, David

2013-04-01

Homogeneous Proto-Slavic genetic substrate and/or extensive mixing after World War II were suggested to explain homogeneity of contemporary Polish paternal lineages. Alternatively, Polish local populations might have displayed pre-war genetic heterogeneity owing to genetic drift and/or gene flow with neighbouring populations. Although sharp genetic discontinuity along the political border between Poland and Germany indisputably results from war-mediated resettlements and homogenisation, it remained unknown whether Y-chromosomal diversity in ethnically/linguistically defined populations was clinal or discontinuous before the war. In order to answer these questions and elucidate early Slavic migrations, 1156 individuals from several Slavic and German populations were analysed, including Polish pre-war regional populations and an autochthonous Slavic population from Germany. Y chromosomes were assigned to 39 haplogroups and genotyped for 19 STRs. Genetic distances revealed similar degree of differentiation of Slavic-speaking pre-war populations from German populations irrespective of duration and intensity of contacts with German speakers. Admixture estimates showed minor Slavic paternal ancestry (~20%) in modern eastern Germans and hardly detectable German paternal ancestry in Slavs neighbouring German populations for centuries. BATWING analysis of isolated Slavic populations revealed that their divergence was preceded by rapid demographic growth, undermining theory that Slavic expansion was primarily linguistic rather than population spread. Polish pre-war regional populations showed within-group heterogeneity and lower STR variation within R-M17 subclades compared with modern populations, which might have been homogenised by war resettlements. Our results suggest that genetic studies on early human history in the Vistula and Oder basins should rely on reconstructed pre-war rather than modern populations.

Divergent strategies for adaptation to desiccation stress in two Drosophila species of immigrans group.

PubMed

Parkash, Ravi; Aggarwal, Dau Dayal; Ranga, Poonam; Singh, Divya

2012-08-01

Water balance mechanisms have been investigated in desert Drosophila species of the subgenus Drosophila from North America, but changes in mesic species of subgenus Drosophila from other continents have received lesser attention. We found divergent strategies for coping with desiccation stress in two species of immigrans group--D. immigrans and D. nasuta. In contrast to clinal variation for body melanization in D. immigrans, cuticular lipid mass showed a positive cline in D. nasuta across a latitudinal transect (10°46'-31°43'N). Based on isofemale lines variability, body melanization showed positive correlation with desiccation resistance in D. immigrans but not in D. nasuta. The use of organic solvents has supported water proofing role of cuticular lipids in D. nasuta but not in D. immigrans. A comparative analysis of water budget of these two species showed that higher water content, reduced rate of water loss and greater dehydration tolerance confer higher desiccation resistance in D. immigrans while the reduced rate of water loss is the only possible mechanism to enhance desiccation tolerance in D. nasuta. We found that carbohydrates act as metabolic fuel during desiccation stress in both the species, whereas their rates of utilization differ significantly between these two species. Further, acclimation to dehydration stress improved desiccation resistance due to increase in the level of carbohydrates in D. immigrans but not in D. nasuta. Thus, populations of D. immigrans and D. nasuta have evolved different water balance mechanisms under shared environmental conditions. Multiple measures of desiccation resistance in D. immigrans but reduction in water loss in D. nasuta are consistent with their different levels of adaptive responses to wet and dry conditions on the Indian subcontinent.

Contemporary paternal genetic landscape of Polish and German populations: from early medieval Slavic expansion to post-World War II resettlements

PubMed Central

Rębała, Krzysztof; Martínez-Cruz, Begoña; Tönjes, Anke; Kovacs, Peter; Stumvoll, Michael; Lindner, Iris; Büttner, Andreas; Wichmann, H-Erich; Siváková, Daniela; Soták, Miroslav; Quintana-Murci, Lluís; Szczerkowska, Zofia; Comas, David

2013-01-01

Homogeneous Proto-Slavic genetic substrate and/or extensive mixing after World War II were suggested to explain homogeneity of contemporary Polish paternal lineages. Alternatively, Polish local populations might have displayed pre-war genetic heterogeneity owing to genetic drift and/or gene flow with neighbouring populations. Although sharp genetic discontinuity along the political border between Poland and Germany indisputably results from war-mediated resettlements and homogenisation, it remained unknown whether Y-chromosomal diversity in ethnically/linguistically defined populations was clinal or discontinuous before the war. In order to answer these questions and elucidate early Slavic migrations, 1156 individuals from several Slavic and German populations were analysed, including Polish pre-war regional populations and an autochthonous Slavic population from Germany. Y chromosomes were assigned to 39 haplogroups and genotyped for 19 STRs. Genetic distances revealed similar degree of differentiation of Slavic-speaking pre-war populations from German populations irrespective of duration and intensity of contacts with German speakers. Admixture estimates showed minor Slavic paternal ancestry (∼20%) in modern eastern Germans and hardly detectable German paternal ancestry in Slavs neighbouring German populations for centuries. BATWING analysis of isolated Slavic populations revealed that their divergence was preceded by rapid demographic growth, undermining theory that Slavic expansion was primarily linguistic rather than population spread. Polish pre-war regional populations showed within-group heterogeneity and lower STR variation within R-M17 subclades compared with modern populations, which might have been homogenised by war resettlements. Our results suggest that genetic studies on early human history in the Vistula and Oder basins should rely on reconstructed pre-war rather than modern populations. PMID:22968131

Uniparental markers of contemporary Italian population reveals details on its pre-Roman heritage.

PubMed

Brisighelli, Francesca; Álvarez-Iglesias, Vanesa; Fondevila, Manuel; Blanco-Verea, Alejandro; Carracedo, Angel; Pascali, Vincenzo L; Capelli, Cristian; Salas, Antonio

2012-01-01

According to archaeological records and historical documentation, Italy has been a melting point for populations of different geographical and ethnic matrices. Although Italy has been a favorite subject for numerous population genetic studies, genetic patterns have never been analyzed comprehensively, including uniparental and autosomal markers throughout the country. A total of 583 individuals were sampled from across the Italian Peninsula, from ten distant (if homogeneous by language) ethnic communities--and from two linguistic isolates (Ladins, Grecani Salentini). All samples were first typed for the mitochondrial DNA (mtDNA) control region and selected coding region SNPs (mtSNPs). This data was pooled for analysis with 3,778 mtDNA control-region profiles collected from the literature. Secondly, a set of Y-chromosome SNPs and STRs were also analyzed in 479 individuals together with a panel of autosomal ancestry informative markers (AIMs) from 441 samples. The resulting genetic record reveals clines of genetic frequencies laid according to the latitude slant along continental Italy--probably generated by demographical events dating back to the Neolithic. The Ladins showed distinctive, if more recent structure. The Neolithic contribution was estimated for the Y-chromosome as 14.5% and for mtDNA as 10.5%. Y-chromosome data showed larger differentiation between North, Center and South than mtDNA. AIMs detected a minor sub-Saharan component; this is however higher than for other European non-Mediterranean populations. The same signal of sub-Saharan heritage was also evident in uniparental markers. Italy shows patterns of molecular variation mirroring other European countries, although some heterogeneity exists based on different analysis and molecular markers. From North to South, Italy shows clinal patterns that were most likely modulated during Neolithic times.

Integrating Evolutionary and Functional Tests of Adaptive Hypotheses: A Case Study of Altitudinal Differentiation in Hemoglobin Function in an Andean Sparrow, Zonotrichia capensis

PubMed Central

Cheviron, Zachary A.; Natarajan, Chandrasekhar; Projecto-Garcia, Joana; Eddy, Douglas K.; Jones, Jennifer; Carling, Matthew D.; Witt, Christopher C.; Moriyama, Hideaki; Weber, Roy E.; Fago, Angela; Storz, Jay F.

2014-01-01

In air-breathing vertebrates, the physiologically optimal blood-O2 affinity is jointly determined by the prevailing partial pressure of atmospheric O2, the efficacy of pulmonary O2 transfer, and internal metabolic demands. Consequently, genetic variation in the oxygenation properties of hemoglobin (Hb) may be subject to spatially varying selection in species with broad elevational distributions. Here we report the results of a combined functional and evolutionary analysis of Hb polymorphism in the rufous-collared sparrow (Zonotrichia capensis), a species that is continuously distributed across a steep elevational gradient on the Pacific slope of the Peruvian Andes. We integrated a population genomic analysis that included all postnatally expressed Hb genes with functional studies of naturally occurring Hb variants, as well as recombinant Hb (rHb) mutants that were engineered through site-directed mutagenesis. We identified three clinally varying amino acid polymorphisms: Two in the αA-globin gene, which encodes the α-chain subunits of the major HbA isoform, and one in the αD-globin gene, which encodes the α-chain subunits of the minor HbD isoform. We then constructed and experimentally tested single- and double-mutant rHbs representing each of the alternative αA-globin genotypes that predominate at different elevations. Although the locus-specific patterns of altitudinal differentiation suggested a history of spatially varying selection acting on Hb polymorphism, the experimental tests demonstrated that the observed amino acid mutations have no discernible effect on respiratory properties of the HbA or HbD isoforms. These results highlight the importance of experimentally validating the hypothesized effects of genetic changes in protein function to avoid the pitfalls of adaptive storytelling. PMID:25135942

Geographic distributions of Idh-1 alleles in a cricket are linked to differential enzyme kinetic performance across thermal environments

PubMed Central

Huestis, Diana L; Oppert, Brenda; Marshall, Jeremy L

2009-01-01

Background Geographic clines within species are often interpreted as evidence of adaptation to varying environmental conditions. However, clines can also result from genetic drift, and these competing hypotheses must therefore be tested empirically. The striped ground cricket, Allonemobius socius, is widely-distributed in the eastern United States, and clines have been documented in both life-history traits and genetic alleles. One clinally-distributed locus, isocitrate dehydrogenase (Idh-1), has been shown previously to exhibit significant correlations between allele frequencies and environmental conditions (temperature and rainfall). Further, an empirical study revealed a significant genotype-by-environmental interaction (GxE) between Idh-1 genotype and temperature which affected fitness. Here, we use enzyme kinetics to further explore GxE between Idh-1 genotype and temperature, and test the predictions of kinetic activity expected under drift or selection. Results We found significant GxE between temperature and three enzyme kinetic parameters, providing further evidence that the natural distributions of Idh-1 allele frequencies in A. socius are maintained by natural selection. Differences in enzyme kinetic activity across temperatures also mirror many of the geographic patterns observed in allele frequencies. Conclusion This study further supports the hypothesis that the natural distribution of Idh-1 alleles in A. socius is driven by natural selection on differential enzymatic performance. This example is one of several which clearly document a functional basis for both the maintenance of common alleles and observed clines in allele frequencies, and provides further evidence for the non-neutrality of some allozyme alleles. PMID:19460149

Lost in Translation: Bioinformatic Analysis of Variations Affecting the Translation Initiation Codon in the Human Genome.

PubMed

Abad, Francisco; de la Morena-Barrio, María Eugenia; Fernández-Breis, Jesualdo Tomás; Corral, Javier

2018-06-01

Translation is a key biological process controlled in eukaryotes by the initiation AUG codon. Variations affecting this codon may have pathological consequences by disturbing the correct initiation of translation. Unfortunately, there is no systematic study describing these variations in the human genome. Moreover, we aimed to develop new tools for in silico prediction of the pathogenicity of gene variations affecting AUG codons, because to date, these gene defects have been wrongly classified as missense. Whole-exome analysis revealed the mean of 12 gene variations per person affecting initiation codons, mostly with high (> 0:01) minor allele frequency (MAF). Moreover, analysis of Ensembl data (December 2017) revealed 11,261 genetic variations affecting the initiation AUG codon of 7,205 genes. Most of these variations (99.5%) have low or unknown MAF, probably reflecting deleterious consequences. Only 62 variations had high MAF. Genetic variations with high MAF had closer alternative AUG downstream codons than did those with low MAF. Besides, the high-MAF group better maintained both the signal peptide and reading frame. These differentiating elements could help to determine the pathogenicity of this kind of variation. Data and scripts in Perl and R are freely available at https://github.com/fanavarro/hemodonacion. jfernand@um.es. Supplementary data are available at Bioinformatics online.

Genetic variation affecting host-parasite interactions: major-effect quantitative trait loci affect the transmission of sigma virus in Drosophila melanogaster.

PubMed

Bangham, Jenny; Knott, Sara A; Kim, Kang-Wook; Young, Robert S; Jiggins, Francis M

2008-09-01

In natural populations, genetic variation affects resistance to disease. Whether that genetic variation comprises lots of small-effect polymorphisms or a small number of large-effect polymorphisms has implications for adaptation, selection and how genetic variation is maintained in populations. Furthermore, how much genetic variation there is, and the genes that underlie this variation, affects models of co-evolution between parasites and their hosts. We are studying the genetic variation that affects the resistance of Drosophila melanogaster to its natural pathogen--the vertically transmitted sigma virus. We have carried out three separate quantitative trait locus mapping analyses to map gene variants on the second chromosome that cause variation in the rate at which males transmit the infection to their offspring. All three crosses identified a locus in a similar chromosomal location that causes a large drop in the rate at which the virus is transmitted. We also found evidence for an additional smaller-effect quantitative trait locus elsewhere on the chromosome. Our data, together with previous experiments on the sigma virus and parasitoid wasps, indicate that the resistance of D. melanogaster to co-evolved pathogens is controlled by a limited number of major-effect polymorphisms.

Divergent drivers of the spatial and temporal variations of cropland carbon transfer in Liaoning province, China.

PubMed

Zhu, Xian-Jin; Zhang, Han-Qi; Zhao, Tian-Hong; Li, Jian-Dong; Yin, Hong

2017-10-12

Spatial and temporal variations are important points of focus in ecological research. Analysing their differences improves our understanding on the variations of ecological phenomena. Using data from the Liaoning Statistical Yearbook, we investigated the spatial and temporal variations of cropland carbon transfer (CCT), an important ecological phenomenon in quantifying the regional carbon budget, in particular, the influencing factors and difference. The results showed that, from 1992 to 2014, the average CCT in Liaoning province was 18.56 TgC yr -1 and decreased from northwest to southeast. CCT spatial variation was primarily affected by the ratio of planting area to regional area (RPR) via its effect on the magnitude of carbon transfer (MCT), which depended mainly on fertilizer usage per area (FUA). From 1992 to 2014, CCT exhibited a significantly increasing trend with a rate of 0.48 TgC yr -1 . The inter-annual variation of CCT was dominated by carbon transfer per planting area (CTP) through its effect on MCT, which significantly correlated with FUA but showed no significant correlation with climatic factors. Therefore, the factors affecting the spatial variation of CCT differed from those that affected its inter-annual variation, indicating that the spatial and temporal variations of ecological phenomena were affected by divergent factors.

Biogeography of Anurans from the Poorly Known and Threatened Coastal Sandplains of Eastern Brazil.

PubMed

Xavier, Ariane Lima; Guedes, Thaís Barreto; Napoli, Marcelo Felgueiras

2015-01-01

The east coast of Brazil comprises an extensive area inserted in the Tropical Atlantic Domain and is represented by sandy plains of beach ridges commonly known as Restingas. The coastal environments are unique and house a rich amphibian fauna, the geographical distribution patterns of which are incipient. Biogeographical studies can explain the current distributional patterns and provide the identification of natural biogeographical units. These areas are important in elucidating the evolutionary history of the taxa and the areas where they occur. The aim of this study was to seek natural biogeographical units in the Brazilian sandy plains of beach ridges by means of distribution data of amphibians and to test the main predictions of the vicariance model to explain the patterns found. We revised and georeferenced data on the geographical distribution of 63 anuran species. We performed a search for latitudinal distribution patterns along the sandy coastal plains of Brazil using the non-metric multidimensional scaling method (NMDS) and the biotic element analysis to identify natural biogeographical units. The results showed a monotonic variation in anuran species composition along the latitudinal gradient with a break in the clinal pattern from 23°S to 25°S latitude (states of Rio de Janeiro to São Paulo). The major predictions of the vicariance model were corroborated by the detection of four biotic elements with significantly clustered distribution and by the presence of congeneric species distributed in distinct biotic elements. The results support the hypothesis that vicariance could be one of the factors responsible for the distribution patterns of the anuran communities along the sandy coastal plains of eastern Brazil. The results of the clusters are also congruent with the predictions of paleoclimatic models made for the Last Glacial Maximum of the Pleistocene, such as the presence of historical forest refugia and biogeographical patterns already detected for amphibians in the Atlantic Rainforest.

Exploring Climate Niches of Ponderosa Pine (Pinus ponderosa Douglas ex Lawson) Haplotypes in the Western United States: Implications for Evolutionary History and Conservation

PubMed Central

Shinneman, Douglas J.; Potter, Kevin M.; Hipkins, Valerie D.

2016-01-01

Ponderosa pine (Pinus ponderosa Douglas ex Lawson) occupies montane environments throughout western North America, where it is both an ecologically and economically important tree species. A recent study using mitochondrial DNA analysis demonstrated substantial genetic variation among ponderosa pine populations in the western U.S., identifying 10 haplotypes with unique evolutionary lineages that generally correspond spatially with distributions of the Pacific (P. p. var. ponderosa) and Rocky Mountain (P. p. var. scopulorum) varieties. To elucidate the role of climate in shaping the phylogeographic history of ponderosa pine, we used nonparametric multiplicative regression to develop predictive climate niche models for two varieties and 10 haplotypes and to hindcast potential distribution of the varieties during the last glacial maximum (LGM), ~22,000 yr BP. Our climate niche models performed well for the varieties, but haplotype models were constrained in some cases by small datasets and unmeasured microclimate influences. The models suggest strong relationships between genetic lineages and climate. Particularly evident was the role of seasonal precipitation balance in most models, with winter- and summer-dominated precipitation regimes strongly associated with P. p. vars. ponderosa and scopulorum, respectively. Indeed, where present-day climate niches overlap between the varieties, introgression of two haplotypes also occurs along a steep clinal divide in western Montana. Reconstructed climate niches for the LGM suggest potentially suitable climate existed for the Pacific variety in the California Floristic province, the Great Basin, and Arizona highlands, while suitable climate for the Rocky Mountain variety may have existed across the southwestern interior highlands. These findings underscore potentially unique phylogeographic origins of modern ponderosa pine evolutionary lineages, including potential adaptations to Pleistocene climates associated with discrete temporary glacial refugia. Our predictive climate niche models may inform strategies for further genetic research (e.g., sampling design) and conservation that promotes haplotype compatibility with projected changes in future climate. PMID:26985674

Integrating evolutionary and functional tests of adaptive hypotheses: a case study of altitudinal differentiation in hemoglobin function in an Andean Sparrow, Zonotrichia capensis.

PubMed

Cheviron, Zachary A; Natarajan, Chandrasekhar; Projecto-Garcia, Joana; Eddy, Douglas K; Jones, Jennifer; Carling, Matthew D; Witt, Christopher C; Moriyama, Hideaki; Weber, Roy E; Fago, Angela; Storz, Jay F

2014-11-01

In air-breathing vertebrates, the physiologically optimal blood-O2 affinity is jointly determined by the prevailing partial pressure of atmospheric O2, the efficacy of pulmonary O2 transfer, and internal metabolic demands. Consequently, genetic variation in the oxygenation properties of hemoglobin (Hb) may be subject to spatially varying selection in species with broad elevational distributions. Here we report the results of a combined functional and evolutionary analysis of Hb polymorphism in the rufous-collared sparrow (Zonotrichia capensis), a species that is continuously distributed across a steep elevational gradient on the Pacific slope of the Peruvian Andes. We integrated a population genomic analysis that included all postnatally expressed Hb genes with functional studies of naturally occurring Hb variants, as well as recombinant Hb (rHb) mutants that were engineered through site-directed mutagenesis. We identified three clinally varying amino acid polymorphisms: Two in the α(A)-globin gene, which encodes the α-chain subunits of the major HbA isoform, and one in the α(D)-globin gene, which encodes the α-chain subunits of the minor HbD isoform. We then constructed and experimentally tested single- and double-mutant rHbs representing each of the alternative α(A)-globin genotypes that predominate at different elevations. Although the locus-specific patterns of altitudinal differentiation suggested a history of spatially varying selection acting on Hb polymorphism, the experimental tests demonstrated that the observed amino acid mutations have no discernible effect on respiratory properties of the HbA or HbD isoforms. These results highlight the importance of experimentally validating the hypothesized effects of genetic changes in protein function to avoid the pitfalls of adaptive storytelling. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biogeography of Anurans from the Poorly Known and Threatened Coastal Sandplains of Eastern Brazil

PubMed Central

Xavier, Ariane Lima; Guedes, Thaís Barreto; Napoli, Marcelo Felgueiras

2015-01-01

The east coast of Brazil comprises an extensive area inserted in the Tropical Atlantic Domain and is represented by sandy plains of beach ridges commonly known as Restingas. The coastal environments are unique and house a rich amphibian fauna, the geographical distribution patterns of which are incipient. Biogeographical studies can explain the current distributional patterns and provide the identification of natural biogeographical units. These areas are important in elucidating the evolutionary history of the taxa and the areas where they occur. The aim of this study was to seek natural biogeographical units in the Brazilian sandy plains of beach ridges by means of distribution data of amphibians and to test the main predictions of the vicariance model to explain the patterns found. We revised and georeferenced data on the geographical distribution of 63 anuran species. We performed a search for latitudinal distribution patterns along the sandy coastal plains of Brazil using the non-metric multidimensional scaling method (NMDS) and the biotic element analysis to identify natural biogeographical units. The results showed a monotonic variation in anuran species composition along the latitudinal gradient with a break in the clinal pattern from 23°S to 25°S latitude (states of Rio de Janeiro to São Paulo). The major predictions of the vicariance model were corroborated by the detection of four biotic elements with significantly clustered distribution and by the presence of congeneric species distributed in distinct biotic elements. The results support the hypothesis that vicariance could be one of the factors responsible for the distribution patterns of the anuran communities along the sandy coastal plains of eastern Brazil. The results of the clusters are also congruent with the predictions of paleoclimatic models made for the Last Glacial Maximum of the Pleistocene, such as the presence of historical forest refugia and biogeographical patterns already detected for amphibians in the Atlantic Rainforest. PMID:26047484

Exploring Climate Niches of Ponderosa Pine (Pinus ponderosa Douglas ex Lawson) Haplotypes in the Western United States: Implications for Evolutionary History and Conservation.

PubMed

Shinneman, Douglas J; Means, Robert E; Potter, Kevin M; Hipkins, Valerie D

2016-01-01

Ponderosa pine (Pinus ponderosa Douglas ex Lawson) occupies montane environments throughout western North America, where it is both an ecologically and economically important tree species. A recent study using mitochondrial DNA analysis demonstrated substantial genetic variation among ponderosa pine populations in the western U.S., identifying 10 haplotypes with unique evolutionary lineages that generally correspond spatially with distributions of the Pacific (P. p. var. ponderosa) and Rocky Mountain (P. p. var. scopulorum) varieties. To elucidate the role of climate in shaping the phylogeographic history of ponderosa pine, we used nonparametric multiplicative regression to develop predictive climate niche models for two varieties and 10 haplotypes and to hindcast potential distribution of the varieties during the last glacial maximum (LGM), ~22,000 yr BP. Our climate niche models performed well for the varieties, but haplotype models were constrained in some cases by small datasets and unmeasured microclimate influences. The models suggest strong relationships between genetic lineages and climate. Particularly evident was the role of seasonal precipitation balance in most models, with winter- and summer-dominated precipitation regimes strongly associated with P. p. vars. ponderosa and scopulorum, respectively. Indeed, where present-day climate niches overlap between the varieties, introgression of two haplotypes also occurs along a steep clinal divide in western Montana. Reconstructed climate niches for the LGM suggest potentially suitable climate existed for the Pacific variety in the California Floristic province, the Great Basin, and Arizona highlands, while suitable climate for the Rocky Mountain variety may have existed across the southwestern interior highlands. These findings underscore potentially unique phylogeographic origins of modern ponderosa pine evolutionary lineages, including potential adaptations to Pleistocene climates associated with discrete temporary glacial refugia. Our predictive climate niche models may inform strategies for further genetic research (e.g., sampling design) and conservation that promotes haplotype compatibility with projected changes in future climate.

Exploring climate niches of ponderosa pine (Pinus ponderosa Douglas ex Lawson) haplotypes in the western United States: Implications for evolutionary history and conservation

USGS Publications Warehouse

Shinneman, Douglas; Means, Robert E.; Potter, Kevin M.; Hipkins, Valerie D.

2016-01-01

Ponderosa pine (Pinus ponderosa Douglas ex Lawson) occupies montane environments throughout western North America, where it is both an ecologically and economically important tree species. A recent study using mitochondrial DNA analysis demonstrated substantial genetic variation among ponderosa pine populations in the western U.S., identifying 10 haplotypes with unique evolutionary lineages that generally correspond spatially with distributions of the Pacific (P. p. var. ponderosa) and Rocky Mountain (P. p. var. scopulorum) varieties. To elucidate the role of climate in shaping the phylogeographic history of ponderosa pine, we used nonparametric multiplicative regression to develop predictive climate niche models for two varieties and 10 haplotypes and to hindcast potential distribution of the varieties during the last glacial maximum (LGM), ~22,000 yr BP. Our climate niche models performed well for the varieties, but haplotype models were constrained in some cases by small datasets and unmeasured microclimate influences. The models suggest strong relationships between genetic lineages and climate. Particularly evident was the role of seasonal precipitation balance in most models, with winter- and summer-dominated precipitation regimes strongly associated with P. p. vars. ponderosa and scopulorum, respectively. Indeed, where present-day climate niches overlap between the varieties, introgression of two haplotypes also occurs along a steep clinal divide in western Montana. Reconstructed climate niches for the LGM suggest potentially suitable climate existed for the Pacific variety in the California Floristic province, the Great Basin, and Arizona highlands, while suitable climate for the Rocky Mountain variety may have existed across the southwestern interior highlands. These findings underscore potentially unique phylogeographic origins of modern ponderosa pine evolutionary lineages, including potential adaptations to Pleistocene climates associated with discrete temporary glacial refugia. Our predictive climate niche models may inform strategies for further genetic research (e.g., sampling design) and conservation that promotes haplotype compatibility with projected changes in future climate.

Edge effects on foliar stable isotope values in a Madagascan tropical dry forest.

PubMed

Crowley, Brooke E; McGoogan, Keriann C; Lehman, Shawn M

2012-01-01

Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ¹³C values where leaves collected close to the forest floor would have lower δ¹³C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ¹³C and δ¹⁵N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ¹³C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ¹³C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ¹⁵N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation biology of forest ecosystems in Madagascar.

Edge Effects on Foliar Stable Isotope Values in a Madagascan Tropical Dry Forest

PubMed Central

Crowley, Brooke E.; McGoogan, Keriann C.; Lehman, Shawn M.

2012-01-01

Edge effects represent an inevitable and important consequence of habitat loss and fragmentation. These effects include changes in microclimate, solar radiation, or temperature. Such abiotic effects can, in turn, impact biotic factors. They can have a substantial impact on species, communities, and ecosystems. Here we examine clinal variations in stable carbon and nitrogen isotope values for trees along an edge-interior gradient in the dry deciduous forest at Ankarafantsika National Park. We predicted that soil respiration and differences in solar irradiance would result in stratified δ13C values where leaves collected close to the forest floor would have lower δ13C values than those growing higher up in the canopy. We also anticipated that plants growing at the savannah-forest boundary would have higher δ13C and δ15N values than plants growing in the forest interior. As expected, we detected a small but significant canopy effect. Leaves growing below 2 m from the forest floor exhibit δ13C values that are, on average, 1.1‰ lower than those growing above this threshold. We did not, however, find any relationship between foliar δ13C and distance from the edge. Unpredictably, we detected a striking positive relationship between foliar δ15N values and increasing distance into the forest interior. Variability in physiology among species, anthropogenic influence, organic input, and rooting depth cannot adequately explain this trend. Instead, this unexpected relationship most likely reflects decreasing nutrient or water availability, or a shift in N-sources with increasing distance from the savannah. Unlike most forest communities, the trees at Ampijoroa are growing in nutrient-limited sands. In addition to being nutrient poor, these well-drained soils likely decrease the amount of soil water available to forest vegetation. Continued research on plant responses to edge effects will improve our understanding of the conservation biology of forest ecosystems in Madagascar. PMID:22973460

Diel Sampling of Groundwater and Surface Water for Trace Elements and Select Water-Quality Constituents at a Former Zinc Smelter Site near Hegeler, Illinois, August 1-3, 2007

USGS Publications Warehouse

Kay, Robert T.; Groschen, George E.; Dupre, David H.; Drexler, Timothy D.; Thingvold, Karen L.; Rosenfeld, Heather J.

2009-01-01

Surface water can exhibit substantial diel variations in the concentration of a number of constituents. Sampling regimens that do not characterize diel variations in water quality can result in an inaccurate understanding of site conditions and of the threat posed by the site to human health and the environment. Surface- and groundwater affected by acid drainage were sampled every 60 to 90 minutes over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, in Hegeler, Ill. Groundwater-quality data from a well at the site indicate stable, low pH, weakly oxidizing geochemical conditions in the aquifer. With the exceptions of temperature and pH, no constituents exhibited diel variations in groundwater. Variations in temperature and pH likely were not representative of conditions in the aquifer. Surface water was sampled at a site on Grape Creek. Diel variations were observed in temperature, dissolved oxygen, pH, and specific conductance, and in the concentrations of nitrite, barium, iron, lead, vanadium, and possibly uranium. Concentrations during the diel cycles varied by about an order of magnitude for nitrite and varied by about a factor of two for barium, iron, lead, vanadium, and uranium. Temperature, dissolved oxygen, specific conductance, nitrite, barium, lead, and uranium generally reached maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally reached minimum values during the afternoon and maximum values during the night. These variations would need to be accounted for during sampling of surface-water quality in similar hydrologic settings. The temperature variations in surface water were affected by variations in air temperature. Concentrations of dissolved oxygen were affected by variations in the intensity of photosynthetic activity and respiration. Nitrite likely was formed by the oxidation of ammonium by dissolved oxygen and degraded by its anaerobic oxidation by ammonium or as part of the decomposition of organic matter. Variations in pH were affected by the photoreduction of Fe3+ to Fe2+ and the precipitation of iron oxyhydroxides. Diel variations in concentrations of iron and vanadium were likely caused by variations in the dissolution and precipitation of iron oxyhydroxides, oxyhydroxysulfates, and hydrous sulfates, which may have been affected by in the intensity of insolation, iron photoreduction, and the concentration of dissolved oxygen. The concentrations of lead, uranium, and perhaps barium in Grape Creek may have been affected by competition for sorption sites on iron oxyhydroxides. Competition for sorption sites was likely affected by variations in pH and the concentration of Fe2+. Constituent concentrations likely also were affected by precipitation and dissolution of minerals that are sensitive to changes in pH, temperature, oxidation-reduction conditions, and biologic activity. The chemical and biologic processes that resulted in the diel variations observed in Grape Creek occurred within the surface-water column or in the underlying sediments.

What Is Beautiful Feels Good: Affective Reactions to Physical Attractiveness.

ERIC Educational Resources Information Center

Carducci, Bernardo J.; Ogan, Tamra A.

Previous research has consistently demonstrated that variations in physical attractiveness elicit different evaluative and behavioral responses. To assess differences in affective responses to variations in physical attractiveness and the affect of sex on those responses, 76 college students (31 male and 45 female) viewed colored slides of an…

Climates Past, Present, and Yet-to-Come Shape Climate Change Vulnerabilities.

PubMed

Nadeau, Christopher P; Urban, Mark C; Bridle, Jon R

2017-10-01

Climate change is altering life at multiple scales, from genes to ecosystems. Predicting the vulnerability of populations to climate change is crucial to mitigate negative impacts. We suggest that regional patterns of spatial and temporal climatic variation scaled to the traits of an organism can predict where and why populations are most vulnerable to climate change. Specifically, historical climatic variation affects the sensitivity and response capacity of populations to climate change by shaping traits and the genetic variation in those traits. Present and future climatic variation can affect both climate change exposure and population responses. We provide seven predictions for how climatic variation might affect the vulnerability of populations to climate change and suggest key directions for future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ethnic Variation in Depressive Symptoms in a Community Sample in Hawai‘i

PubMed Central

Kanazawa, Asako; White, Patricia M.; Hampson, Sarah E.

2008-01-01

A modified CES-D was administered to a community sample of 176 European Americans (EA), 209 Native Hawaiians (NH), and 357 Japanese Americans (JA), yielding measures of depression, positive affect, depressed affect, somatic disturbance and disturbed interpersonal relations. Positive affect was lower in JA relative to EA, consistent with findings among Native Japanese, a pattern attributed to cultural variation in emotion regulation. NH reported lower positive affect than EA, accompanied by elevated negative affect and somatic disturbance, suggesting generally higher levels of depressive symptoms. The three ethnic groups varied in mental healthcare usage with differing associations between depressive symptoms and experiences of stressful life events. Taken together, these results suggest ethnic variation in depressive symptoms may arise from differing cultural beliefs. PMID:17227175

[Application of regression tree in analyzing the effects of climate factors on NDVI in loess hilly area of Shaanxi Province].

PubMed

Liu, Yang; Lü, Yi-he; Zheng, Hai-feng; Chen, Li-ding

2010-05-01

Based on the 10-day SPOT VEGETATION NDVI data and the daily meteorological data from 1998 to 2007 in Yan' an City, the main meteorological variables affecting the annual and interannual variations of NDVI were determined by using regression tree. It was found that the effects of test meteorological variables on the variability of NDVI differed with seasons and time lags. Temperature and precipitation were the most important meteorological variables affecting the annual variation of NDVI, and the average highest temperature was the most important meteorological variable affecting the inter-annual variation of NDVI. Regression tree was very powerful in determining the key meteorological variables affecting NDVI variation, but could not build quantitative relations between NDVI and meteorological variables, which limited its further and wider application.

Highly polygenic variation in environmental perception determines dauer larvae formation in growing populations of Caenorhabditis elegans.

PubMed

Green, James W M; Stastna, Jana J; Orbidans, Helen E; Harvey, Simon C

2014-01-01

Determining how complex traits are genetically controlled is a requirement if we are to predict how they evolve and how they might respond to selection. This requires understanding how distinct, and often more simple, life history traits interact and change in response to environmental conditions. In order to begin addressing such issues, we have been analyzing the formation of the developmentally arrested dauer larvae of Caenorhabditis elegans under different conditions. We find that 18 of 22 previously identified quantitative trait loci (QTLs) affecting dauer larvae formation in growing populations, assayed by determining the number of dauer larvae present at food patch exhaustion, can be recovered under various environmental conditions. We also show that food patch size affects both the ability to detect QTLs and estimates of effect size, and demonstrate that an allele of nath-10 affects dauer larvae formation in growing populations. To investigate the component traits that affect dauer larvae formation in growing populations we map, using the same introgression lines, QTLs that affect dauer larvae formation in response to defined amounts of pheromone. This identifies 36 QTLs, again demonstrating the highly polygenic nature of the genetic variation underlying dauer larvae formation. These data indicate that QTLs affecting the number of dauer larvae at food exhaustion in growing populations of C. elegans are highly reproducible, and that nearly all can be explained by variation affecting dauer larvae formation in response to defined amounts of pheromone. This suggests that most variation in dauer larvae formation in growing populations is a consequence of variation in the perception of the food and pheromone environment (i.e. chemosensory variation) and in the integration of these cues.

Consensus and stratification in the affective meaning of human sociality

PubMed Central

Ambrasat, Jens; von Scheve, Christian; Conrad, Markus; Schauenburg, Gesche; Schröder, Tobias

2014-01-01

We investigate intrasocietal consensus and variation in affective meanings of concepts related to authority and community, two elementary forms of human sociality. Survey participants (n = 2,849) from different socioeconomic status (SES) groups in German society provided ratings of 909 social concepts along three basic dimensions of affective meaning. Results show widespread consensus on these meanings within society and demonstrate that a meaningful structure of socially shared knowledge emerges from organizing concepts according to their affective similarity. The consensus finding is further qualified by evidence for subtle systematic variation along SES differences. In relation to affectively neutral words, high-status individuals evaluate intimacy-related and socially desirable concepts as less positive and powerful than middle- or low-status individuals, while perceiving antisocial concepts as relatively more threatening. This systematic variation across SES groups suggests that the affective meaning of sociality is to some degree a function of social stratification. PMID:24843121

Effect of location in the canopy on the colour development of three apple cultivars during growth.

PubMed

Unuk, Tatjana; Tijskens, L M M Pol; Germšek, Blaž; Zadravec, Peter; Vogrin, Andrej; Hribar, Janez; Simčič, Marjan; Tojnko, Stanislav

2012-09-01

Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. The red-coloured apple cultivar (Gala) depends more on the location in the canopy than the less-coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development. Copyright © 2012 Society of Chemical Industry.

[The ways in which variations in space and atmospheric factors act upon the biosphere and humans].

PubMed

Chernogor, L F

2010-01-01

The system analysis is validated to be an efficient means for studying the channels through which variations in space and tropospheric weather affect the biosphere (humans). The basics of the system analysis paradigm are presented. The causes of variations in space and tropospheric weather are determined, and the interrelations between them are demonstrated. The ways in which these variations affect the biosphere (humans) are discussed. Aperiodic and quasi-periodic disturbances in the physical fields that influence the biosphere (humans) are intercompared.

Reinforcement and a cline in mating behaviour evolve in response to secondary contact and hybridization in shield-back katydids (Orthoptera: Tettigoniidae).

PubMed

Cole, J A

2016-09-01

In a dispersal-limited species that has evolved reproductive character displacement at a contact zone, a cline in mating behaviour may result if gene flow diffuses alleles out of the contact zone into allopatric populations. Prior work has found such a clinal pattern in the shield-back katydid Aglaothorax morsei, in which the male calling songs in a sympatric population have a displaced, short interpulse interval that increases in length with increasing distance from the contact zone. In this study, molecular phylogenetic and female preference data show that (1) sympatric populations result from secondary contact, (2) hybridization in sympatry has resulted in unidirectional mitochondrial introgression and (3) female preferences are consistent with reproductive character displacement and could generate a cline in mating behaviour. These data together suggest a history of reinforcement, generally considered rare in acoustically communicating insects; thus, Aglaothorax represents an important example of a rarely documented evolutionary process. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Dual Annual Spawning Races in Atlantic Sturgeon

PubMed Central

Balazik, Matthew T.; Musick, John A.

2015-01-01

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures. PMID:26020631

Winter color polymorphisms identify global hot spots for evolutionary rescue from climate change.

PubMed

Mills, L Scott; Bragina, Eugenia V; Kumar, Alexander V; Zimova, Marketa; Lafferty, Diana J R; Feltner, Jennifer; Davis, Brandon M; Hackländer, Klaus; Alves, Paulo C; Good, Jeffrey M; Melo-Ferreira, José; Dietz, Andreas; Abramov, Alexei V; Lopatina, Natalia; Fay, Kairsten

2018-03-02

Maintenance of biodiversity in a rapidly changing climate will depend on the efficacy of evolutionary rescue, whereby population declines due to abrupt environmental change are reversed by shifts in genetically driven adaptive traits. However, a lack of traits known to be under direct selection by anthropogenic climate change has limited the incorporation of evolutionary processes into global conservation efforts. In 21 vertebrate species, some individuals undergo a seasonal color molt from summer brown to winter white as camouflage against snow, whereas other individuals remain brown. Seasonal snow duration is decreasing globally, and fitness is lower for winter white animals on snowless backgrounds. Based on 2713 georeferenced samples of known winter coat color-from eight species across trophic levels-we identify environmentally driven clinal gradients in winter coat color, including polymorphic zones where winter brown and white morphs co-occur. These polymorphic zones, underrepresented by existing global protected area networks, indicate hot spots for evolutionary rescue in a changing climate. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Weather explains high annual variation in butterfly dispersal

PubMed Central

Rytteri, Susu; Heikkinen, Risto K.; Heliölä, Janne; von Bagh, Peter

2016-01-01

Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark–release–recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79–91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming. PMID:27440662

Seasonal and geothermal production variations in concentrations of He and CO2 in soil gases, Roosevelt Hot Springs Known Geothermal Resource Area, Utah, U.S.A.

USGS Publications Warehouse

Hinkle, M.E.

1991-01-01

To increase understanding of natural variations in soil gas concentrations, CO2, He, O2 and N2 were measured in soil gases collected regularly for several months from four sites at the Roosevelt Hot Springs Known Geothermal Resource Area, Utah. Soil temperature, air temperature, per cent relative humidity, barometric pressure and amounts of rain and snowfall were also monitored to determine the effect of meteorological parameters on concentrations of the measured gases. Considerable seasonal variation existed in concentrations of CO2 and He. The parameters that most affected the soil-gas concentrations were soil and air temperatures. Moisture from rain and snow probably affected the soil-gas concentrations also. However, annual variations in meteorological parameters did not appear to affect measurements of anomalous concentrations in samples collected within a time period of a few days. Production from some of the geothermal wells probably affected the soil-gas concentrations. ?? 1990.

The impact of nectar chemical features on phenotypic variation in two related nectar yeasts.

PubMed

Pozo, María I; Herrera, Carlos M; Van den Ende, Wim; Verstrepen, Kevin; Lievens, Bart; Jacquemyn, Hans

2015-06-01

Floral nectars become easily colonized by microbes, most often species of the ascomycetous yeast genus Metschnikowia. Although it is known that nectar composition can vary tremendously among plant species, most probably corresponding to the nutritional requirements of their main pollinators, far less is known about how variation in nectar chemistry affects intraspecific variation in nectarivorous yeasts. Because variation in nectar traits probably affects growth and abundance of nectar yeasts, nectar yeasts can be expected to display large phenotypic variation in order to cope with varying nectar conditions. To test this hypothesis, we related variation in the phenotypic landscape of a vast collection of nectar-living yeast isolates from two Metschnikowia species (M. reukaufii and M. gruessii) to nectar chemical traits using non-linear redundancy analyses. Nectar yeasts were collected from 19 plant species from different plant families to include as much variation in nectar chemical traits as possible. As expected, nectar yeasts displayed large variation in phenotypic traits, particularly in traits related to growth performance in carbon sources and inhibitors, which was significantly related to the host plant from which they were isolated. Total sugar concentration and relative fructose content significantly explained the observed variation in the phenotypic profile of the investigated yeast species, indicating that sugar concentration and composition are the key traits that affect phenotypic variation in nectarivorous yeasts. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Climatic Versus Biotic Constraints on Carbon and Water Fluxes in Seasonally Drought-affected Ponderosa Pine Ecosystems. Chapter 2

NASA Technical Reports Server (NTRS)

Schwarz, P. A.; Law, B. E.; Williams, M.; Irvine, J.; Kurpius, M.; Moore, D.

2005-01-01

We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

Speed, age, sex, and body mass index provide a rigorous basis for comparing the kinematic and kinetic profiles of the lower extremity during walking.

PubMed

Chehab, E F; Andriacchi, T P; Favre, J

2017-06-14

The increased use of gait analysis has raised the need for a better understanding of how walking speed and demographic variations influence asymptomatic gait. Previous analyses mainly reported relationships between subsets of gait features and demographic measures, rendering it difficult to assess whether gait features are affected by walking speed or other demographic measures. The purpose of this study was to conduct a comprehensive analysis of the kinematic and kinetic profiles during ambulation that tests for the effect of walking speed in parallel to the effects of age, sex, and body mass index. This was accomplished by recruiting a population of 121 asymptomatic subjects and analyzing characteristic 3-dimensional kinematic and kinetic features at the ankle, knee, hip, and pelvis during walking trials at slow, normal, and fast speeds. Mixed effects linear regression models were used to identify how each of 78 discrete gait features is affected by variations in walking speed, age, sex, and body mass index. As expected, nearly every feature was associated with variations in walking speed. Several features were also affected by variations in demographic measures, including age affecting sagittal-plane knee kinematics, body mass index affecting sagittal-plane pelvis and hip kinematics, body mass index affecting frontal-plane knee kinematics and kinetics, and sex affecting frontal-plane kinematics at the pelvis, hip, and knee. These results could aid in the design of future studies, as well as clarify how walking speed, age, sex, and body mass index may act as potential confounders in studies with small populations or in populations with insufficient demographic variations for thorough statistical analyses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Variation of NEE and its affecting factors in a vineyard of arid region of northwest China

NASA Astrophysics Data System (ADS)

Guo, W. H.; Kang, S. Z.; Li, F. S.; Li, S. E.

2014-02-01

To understand the variation of net ecosystem CO2 exchange (NEE) in orchard ecosystem and it's affecting factors, carbon flux was measured using eddy covariance system in a wine vineyard in arid northwest China during 2008-2010. Results show that vineyard NEE was positive value at the early growth stage, higher negative value at the mid-growth stage, and lower negative value at the later growth stage. Diurnal variation of NEE was "W" shaped curve in sunny day, but "U" shaped curve in cloudy day. Irrigation and pruning did not affect diurnal variation shape of NEE, however, irrigation reduced the difference between maximal and minimal value of NEE and pruning reduced the carbon sink capacity. The main factors affecting hourly NEE were canopy conductance (gc) and net radiation (Rn). The hourly NEE increased with the increase of gc or Rn when gc was less than 0.02 m·s-1 or Rn was between 0 and 200 W·m-2. The main factors affecting both daily and seasonal NEE were gc, air temperature (Ta), atmospheric CO2 density, vapour pressure deficit (VPD) and soil moisture content.

Selective Pressure along a Latitudinal Gradient Affects Subindividual Variation in Plants

PubMed Central

Sobral, Mar; Guitián, José; Guitián, Pablo; Larrinaga, Asier R.

2013-01-01

Individual plants produce repeated structures such as leaves, flowers or fruits, which, although belonging to the same genotype, are not phenotypically identical. Such subindividual variation reflects the potential of individual genotypes to vary with micro-environmental conditions. Furthermore, variation in organ traits imposes costs to foraging animals such as time, energy and increased predation risk. Therefore, animals that interact with plants may respond to this variation and affect plant fitness. Thus, phenotypic variation within an individual plant could be, in part, an adaptive trait. Here we investigated this idea and we found that subindividual variation of fruit size of Crataegus monogyna, in different populations throughout the latitudinal gradient in Europe, was explained at some extent by the selective pressures exerted by seed-dispersing birds. These findings support the hypothesis that within-individual variation in plants is an adaptive trait selected by interacting animals which may have important implications for plant evolution. PMID:24069297

Multiple Insecticide Resistances in the Disease Vector Culex p. Quinquefasciatus from Western Indian Ocean

PubMed Central

Pocquet, Nicolas; Milesi, Pascal; Makoundou, Patrick; Unal, Sandra; Zumbo, Betty; Atyame, Célestine; Darriet, Frédéric; Dehecq, Jean-Sébastien; Thiria, Julien; Bheecarry, Ambicadutt; Iyaloo, Diana P.; Weill, Mylène; Chandre, Fabrice; Labbé, Pierrick

2013-01-01

Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC), Organophosphates (OP) and pyrethroids (PYR) families. However, mosquito control failures have been reported on site, and they were probably due to the selection of resistant individuals in response to insecticide exposure. In this study, we used different approaches to establish a first regional assessment of the levels and mechanisms of resistance to various insecticides. Bioassays were used to evaluate resistance to various insecticides, enzyme activity was measured to assess the presence of metabolic resistances through elevated detoxification, and molecular identification of known resistance alleles was investigated to determine the frequency of target-site mutations. These complementary approaches showed that resistance to the most used insecticides families (OC, OP and PYR) is widespread at a regional scale. However, the distribution of the different resistance genes is quite heterogeneous among the islands, some being found at high frequencies everywhere, others being frequent in some islands and absent in others. Moreover, two resistance alleles displayed clinal distributions in Mayotte and La Réunion, probably as a result of a heterogeneous selection due to local treatment practices. These widespread and diverse resistance mechanisms reduce the capacity of resistance management through classical strategies (e.g. insecticide rotation). In case of a disease outbreak, it could undermine the efforts of the vector control services, as only few compounds could be used. It thus becomes urgent to find alternatives to control populations of Cx. p. quinquefasciatus in the Indian Ocean. PMID:24204997

Small area-level variation in the incidence of psychotic disorders in an urban area in France: an ecological study.

PubMed

Szoke, Andrei; Pignon, Baptiste; Baudin, Grégoire; Tortelli, Andrea; Richard, Jean-Romain; Leboyer, Marion; Schürhoff, Franck

2016-07-01

We sought to determine whether significant variation in the incidence of clinically relevant psychoses existed at an ecological level in an urban French setting, and to examine possible factors associated with this variation. We aimed to advance the literature by testing this hypothesis in a novel population setting and by comparing a variety of spatial models. We sought to identify all first episode cases of non-affective and affective psychotic disorders presenting in a defined urban catchment area over a 4 years period, over more than half a million person-years at-risk. Because data from geographic close neighbourhoods usually show spatial autocorrelation, we used for our analyses Bayesian modelling. We included small area neighbourhood measures of deprivation, migrants' density and social fragmentation as putative explanatory variables in the models. Incidence of broad psychotic disorders shows spatial patterning with the best fit for models that included both strong autocorrelation between neighbouring areas and weak autocorrelation between areas further apart. Affective psychotic disorders showed similar spatial patterning and were associated with the proportion of migrants/foreigners in the area (inverse correlation). In contrast, non-affective psychoses did not show spatial patterning. At ecological level, the variation in the number of cases and the factors that influence this variation are different for non-affective and affective psychotic disorders. Important differences in results-compared with previous studies in different settings-point to the importance of the context and the necessity of further studies to understand these differences.

Physiological correlates of ecological divergence along an urbanization gradient: differential tolerance to ammonia among molecular forms of the malaria mosquito Anopheles gambiae

PubMed Central

2013-01-01

Background Limitations in the ability of organisms to tolerate environmental stressors affect their fundamental ecological niche and constrain their distribution to specific habitats. Evolution of tolerance, therefore, can engender ecological niche dynamics. Forest populations of the afro-tropical malaria mosquito Anopheles gambiae have been shown to adapt to historically unsuitable larval habitats polluted with decaying organic matter that are found in densely populated urban agglomerates of Cameroon. This process has resulted in niche expansion from rural to urban environments that is associated with cryptic speciation and ecological divergence of two evolutionarily significant units within this taxon, the molecular forms M and S, among which reproductive isolation is significant but still incomplete. Habitat segregation between the two forms results in a mosaic distribution of clinally parapatric patches, with the M form predominating in the centre of urban agglomerates and the S form in the surrounding rural localities. We hypothesized that development of tolerance to nitrogenous pollutants derived from the decomposition of organic matter, among which ammonia is the most toxic to aquatic organisms, may affect this pattern of distribution and process of niche expansion by the M form. Results Acute toxicity bioassays indicated that populations of the two molecular forms occurring at the extremes of an urbanization gradient in Yaounde, the capital of Cameroon, differed in their response to ammonia. The regression lines best describing the dose-mortality profile differed in the scale of the explanatory variable (ammonia concentration log-transformed for the S form and linear for the M form), and in slope (steeper for the S form and shallower for the M form). These features reflected differences in the frequency distribution of individual tolerance thresholds in the two populations as assessed by probit analysis, with the M form exhibiting a greater mean and variance compared to the S form. Conclusions In agreement with expectations based on the pattern of habitat partitioning and exposure to ammonia in larval habitats in Yaounde, the M form showed greater tolerance to ammonia compared to the S form. This trait may be part of the physiological machinery allowing forest populations of the M form to colonize polluted larval habitats, which is at the heart of its niche expansion in densely populated human settlements in Cameroon. PMID:23294940

Weather explains high annual variation in butterfly dispersal.

PubMed

Kuussaari, Mikko; Rytteri, Susu; Heikkinen, Risto K; Heliölä, Janne; von Bagh, Peter

2016-07-27

Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark-release-recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79-91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming. © 2016 The Author(s).

Flower color preferences of insects and livestock: effects on Gentiana lutea reproductive success.

PubMed

Sobral, Mar; Losada, María; Veiga, Tania; Guitián, Javier; Guitián, José; Guitián, Pablo

2016-01-01

Angiosperms diversification was primarily driven by pollinator agents, but non-pollinator agents also promoted floral evolution. Gentiana lutea shows pollinator driven flower color variation in NW Spain. We test whether insect herbivores and livestock, which frequently feed in G.lutea, play a role in G. lutea flower color variation, by answering the following questions: (i) Do insect herbivores and grazing livestock show flower color preferences when feeding on G. lutea? (ii) Do mutualists (pollinators) and antagonists (seed predators, insect herbivores and livestock) jointly affect G. lutea reproductive success? Insect herbivores fed more often on yellow flowering individuals but they did not affect seed production, whereas livestock affected seed production but did not show clear color preferences. Our data indicate that flower color variation of G. lutea is not affected by insect herbivores or grazing livestock.

Flower color preferences of insects and livestock: effects on Gentiana lutea reproductive success

PubMed Central

Losada, María; Veiga, Tania; Guitián, Javier; Guitián, José; Guitián, Pablo

2016-01-01

Angiosperms diversification was primarily driven by pollinator agents, but non-pollinator agents also promoted floral evolution. Gentiana lutea shows pollinator driven flower color variation in NW Spain. We test whether insect herbivores and livestock, which frequently feed in G.lutea, play a role in G. lutea flower color variation, by answering the following questions: (i) Do insect herbivores and grazing livestock show flower color preferences when feeding on G. lutea? (ii) Do mutualists (pollinators) and antagonists (seed predators, insect herbivores and livestock) jointly affect G. lutea reproductive success? Insect herbivores fed more often on yellow flowering individuals but they did not affect seed production, whereas livestock affected seed production but did not show clear color preferences. Our data indicate that flower color variation of G. lutea is not affected by insect herbivores or grazing livestock. PMID:27014509

Genetic and Epigenetic Variations Induced by Wheat-Rye 2R and 5R Monosomic Addition Lines

PubMed Central

Fu, Shulan; Sun, Chuanfei; Yang, Manyu; Fei, Yunyan; Tan, Feiqun; Yan, Benju; Ren, Zhenglong; Tang, Zongxiang

2013-01-01

Background Monosomic alien addition lines (MAALs) can easily induce structural variation of chromosomes and have been used in crop breeding; however, it is unclear whether MAALs will induce drastic genetic and epigenetic alterations. Methodology/Principal Findings In the present study, wheat-rye 2R and 5R MAALs together with their selfed progeny and parental common wheat were investigated through amplified fragment length polymorphism (AFLP) and methylation-sensitive amplification polymorphism (MSAP) analyses. The MAALs in different generations displayed different genetic variations. Some progeny that only contained 42 wheat chromosomes showed great genetic/epigenetic alterations. Cryptic rye chromatin has introgressed into the wheat genome. However, one of the progeny that contained cryptic rye chromatin did not display outstanding genetic/epigenetic variation. 78 and 49 sequences were cloned from changed AFLP and MSAP bands, respectively. Blastn search indicated that almost half of them showed no significant similarity to known sequences. Retrotransposons were mainly involved in genetic and epigenetic variations. Genetic variations basically affected Gypsy-like retrotransposons, whereas epigenetic alterations affected Copia-like and Gypsy-like retrotransposons equally. Genetic and epigenetic variations seldom affected low-copy coding DNA sequences. Conclusions/Significance The results in the present study provided direct evidence to illustrate that monosomic wheat-rye addition lines could induce different and drastic genetic/epigenetic variations and these variations might not be caused by introgression of rye chromatins into wheat. Therefore, MAALs may be directly used as an effective means to broaden the genetic diversity of common wheat. PMID:23342073

Genetic and epigenetic variations induced by wheat-rye 2R and 5R monosomic addition lines.

PubMed

Fu, Shulan; Sun, Chuanfei; Yang, Manyu; Fei, Yunyan; Tan, Feiqun; Yan, Benju; Ren, Zhenglong; Tang, Zongxiang

2013-01-01

Monosomic alien addition lines (MAALs) can easily induce structural variation of chromosomes and have been used in crop breeding; however, it is unclear whether MAALs will induce drastic genetic and epigenetic alterations. In the present study, wheat-rye 2R and 5R MAALs together with their selfed progeny and parental common wheat were investigated through amplified fragment length polymorphism (AFLP) and methylation-sensitive amplification polymorphism (MSAP) analyses. The MAALs in different generations displayed different genetic variations. Some progeny that only contained 42 wheat chromosomes showed great genetic/epigenetic alterations. Cryptic rye chromatin has introgressed into the wheat genome. However, one of the progeny that contained cryptic rye chromatin did not display outstanding genetic/epigenetic variation. 78 and 49 sequences were cloned from changed AFLP and MSAP bands, respectively. Blastn search indicated that almost half of them showed no significant similarity to known sequences. Retrotransposons were mainly involved in genetic and epigenetic variations. Genetic variations basically affected Gypsy-like retrotransposons, whereas epigenetic alterations affected Copia-like and Gypsy-like retrotransposons equally. Genetic and epigenetic variations seldom affected low-copy coding DNA sequences. The results in the present study provided direct evidence to illustrate that monosomic wheat-rye addition lines could induce different and drastic genetic/epigenetic variations and these variations might not be caused by introgression of rye chromatins into wheat. Therefore, MAALs may be directly used as an effective means to broaden the genetic diversity of common wheat.

Anatomical variations of the carpal tunnel structures

PubMed Central

Mitchell, Ryan; Chesney, Amy; Seal, Shane; McKnight, Leslie; Thoma, Achilleas

2009-01-01

There are many anatomical variations in and around the carpal tunnel that affect the nerves, tendons and arteries in this area. Awareness of these variations is important both during the clinical examination and during carpal tunnel release. The purpose of the present review is to highlight recognized anatomical variations within the carpal tunnel including variation in nerve anatomy, tendon anatomical variants, vascular anatomical variations and muscle anatomical variations. PMID:20808747

The epigenomic landscape of African rainforest hunter-gatherers and farmers.

PubMed

Fagny, Maud; Patin, Etienne; MacIsaac, Julia L; Rotival, Maxime; Flutre, Timothée; Jones, Meaghan J; Siddle, Katherine J; Quach, Hélène; Harmant, Christine; McEwen, Lisa M; Froment, Alain; Heyer, Evelyne; Gessain, Antoine; Betsem, Edouard; Mouguiama-Daouda, Patrick; Hombert, Jean-Marie; Perry, George H; Barreiro, Luis B; Kobor, Michael S; Quintana-Murci, Lluis

2015-11-30

The genetic history of African populations is increasingly well documented, yet their patterns of epigenomic variation remain uncharacterized. Moreover, the relative impacts of DNA sequence variation and temporal changes in lifestyle and habitat on the human epigenome remain unknown. Here we generate genome-wide genotype and DNA methylation profiles for 362 rainforest hunter-gatherers and sedentary farmers. We find that the current habitat and historical lifestyle of a population have similarly critical impacts on the methylome, but the biological functions affected strongly differ. Specifically, methylation variation associated with recent changes in habitat mostly concerns immune and cellular functions, whereas that associated with historical lifestyle affects developmental processes. Furthermore, methylation variation--particularly that correlated with historical lifestyle--shows strong associations with nearby genetic variants that, moreover, are enriched in signals of natural selection. Our work provides new insight into the genetic and environmental factors affecting the epigenomic landscape of human populations over time.

Affective and Behavioral Features of Jealousy Protest: Associations with Child Temperament, Maternal Interaction Style, and Attachment

ERIC Educational Resources Information Center

Hart, Sybil L.; Behrens, Kazuko Y.

2013-01-01

This study explored variation in affective and behavioral components of infants' jealousy protests during an eliciting condition in which mother and an experimenter directed differential attention exclusively toward a rival. Variation was examined in relation to child temperamental emotionality, maternal interaction style, and attachment security.…

Variation among edible podded snap bean accessions for pod and seed sugar content

USDA-ARS?s Scientific Manuscript database

Sugar content of immature snap bean (Phaseolus vulgaris) pods and the effects of sugars on other flavor compounds are important to consumers and affect their food and vegetable choices. The objective of this study was to identify variation within Phaseolus vulgaris in relation to sugars that affect ...

Impact of intra- versus inter-annual snow depth variation on water relations and photosynthesis for two Great Basin Desert shrubs.

PubMed

Loik, Michael E; Griffith, Alden B; Alpert, Holly; Concilio, Amy L; Wade, Catherine E; Martinson, Sharon J

2015-06-01

Snowfall provides the majority of soil water in certain ecosystems of North America. We tested the hypothesis that snow depth variation affects soil water content, which in turn drives water potential (Ψ) and photosynthesis, over 10 years for two widespread shrubs of the western USA. Stem Ψ (Ψ stem) and photosynthetic gas exchange [stomatal conductance to water vapor (g s), and CO2 assimilation (A)] were measured in mid-June each year from 2004 to 2013 for Artemisia tridentata var. vaseyana (Asteraceae) and Purshia tridentata (Rosaceae). Snow fences were used to create increased or decreased snow depth plots. Snow depth on +snow plots was about twice that of ambient plots in most years, and 20 % lower on -snow plots, consistent with several down-scaled climate model projections. Maximal soil water content at 40- and 100-cm depths was correlated with February snow depth. For both species, multivariate ANOVA (MANOVA) showed that Ψ stem, g s, and A were significantly affected by intra-annual variation in snow depth. Within years, MANOVA showed that only A was significantly affected by spatial snow depth treatments for A. tridentata, and Ψ stem was significantly affected by snow depth for P. tridentata. Results show that stem water relations and photosynthetic gas exchange for these two cold desert shrub species in mid-June were more affected by inter-annual variation in snow depth by comparison to within-year spatial variation in snow depth. The results highlight the potential importance of changes in inter-annual variation in snowfall for future shrub photosynthesis in the western Great Basin Desert.

Relationships between Genetic Variations of PNPLA3, TM6SF2 and Histological Features of Nonalcoholic Fatty Liver Disease in Japan.

PubMed

Akuta, Norio; Kawamura, Yusuke; Arase, Yasuji; Suzuki, Fumitaka; Sezaki, Hitomi; Hosaka, Tetsuya; Kobayashi, Masahiro; Kobayashi, Mariko; Saitoh, Satoshi; Suzuki, Yoshiyuki; Ikeda, Kenji; Kumada, Hiromitsu

2016-05-23

It is important to determine the noninvasive parameters of histological features in nonalcoholic fatty liver disease (NAFLD). The aim of this study was to investigate the value of genetic variations as surrogate markers of histological features. The parameters that affected the histological features of NAFLD were investigated in 211 Japanese patients with biopsy-proven NAFLD. The relationships between genetic variations in PNPLA3 rs738409 or TM6SF2 rs58542926 and histological features were analyzed. Furthermore, the impact of genetic variations that affected the pathological criteria for the diagnosis of nonalcoholic steatohepatitis (NASH) (Matteoni classification and NAFLD activity score) was evaluated. The fibrosis stage of PNPLA3 GG was significantly more progressive than that of CG by multiple comparisons. Multivariate analysis identified PNPLA3 genotypes as predictors of fibrosis of stage 2 or more, but the impact tended to decrease at stage 3 or greater. There were no significant differences among the histological features of the three genotypes of TM6SF2. PNPLA3 genotypes partly affected the definition of NASH by the NAFLD activity score, but TM6SF2 genotypes did not affect the definition of NASH. In Japanese patients with biopsy-proven NAFLD, PNPLA3 genotypes may partly affect histological features, including stage of fibrosis, but the TM6SF2 genotype does not affect histological features.

Fossil shrews from Honduras and their significance for late glacial evolution in body size (Mammalia: Soricidae: Cryptotis)

USGS Publications Warehouse

Woodman, N.; Croft, D.A.

2005-01-01

Our study of mammalian remains excavated in the 1940s from McGrew Cave, north of Copan, Honduras, yielded an assemblage of 29 taxa that probably accumulated predominantly as the result of predation by owls. Among the taxa present are three species of small-eared shrews, genus Cryptotis. One species, Cryptotis merriami, is relatively rare among the fossil remains. The other two shrews, Cryptotis goodwini and Cryptotis orophila, are abundant and exhibit morpho metrical variation distinguishing them from modern populations. Fossils of C. goodwini are distinctly and consistently smaller than modern members of the species. To quantify the size differences, we derived common measures of body size for fossil C. goodwini using regression models based on modern samples of shrews in the Cryptotis mexicana-group. Estimated mean length of head and body for the fossil sample is 72-79 mm, and estimated mean mass is 7.6-9.6 g. These numbers indicate that the fossil sample averaged 6-14% smaller in head and body length and 39-52% less in mass than the modern sample and that increases of 6-17% in head and body length and 65-108% in mass occurred to achieve the mean body size of the modern sample. Conservative estimates of fresh (wet) food intake based on mass indicate that such a size increase would require a 37-58% increase in daily food consumption. In contrast to C. goodwini, fossil C. orophila from the cave is not different in mean body size from modern samples. The fossil sample does, however, show slightly greater variation in size than is currently present throughout the modern geographical distribution of the taxon. Moreover, variation in some other dental and mandibular characters is more constrained, exhibiting a more direct relationship to overall size. Our study of these species indicates that North American shrews have not all been static in size through time, as suggested by some previous work with fossil soricids. Lack of stratigraphic control within the site and our failure to obtain reliable radiometric dates on remains restrict our opportunities to place the site in a firm temporal context. However, the morphometrical differences we document for fossil C. orophila and C. goodwini show them to be distinct from modern populations of these shrews. Some other species of fossil mammals from McGrew Cave exhibit distinct size changes of the magnitudes experienced by many northern North American and some Mexican mammals during the transition from late glacial to Holocene environmental conditions, and it is likely that at least some of the remains from the cave are late Pleistocene in age. One curious factor is that, whereas most mainland mammals that exhibit large-scale size shifts during the late glacial/postglacial transition experienced dwarfing, C. goodwini increased in size. The lack of clinal variation in modern C. goodwini supports the hypothesis that size evolution can result from local selection rather than from cline translocation. Models of size change in mammals indicate that increased size, such as that observed for C. goodwini, are a likely consequence of increased availability of resources and, thereby, a relaxation of selection during critical times of the year.

Tissue culture-induced genetic and epigenetic variation in triticale (× Triticosecale spp. Wittmack ex A. Camus 1927) regenerants.

PubMed

Machczyńska, Joanna; Zimny, Janusz; Bednarek, Piotr Tomasz

2015-10-01

Plant regeneration via in vitro culture can induce genetic and epigenetic variation; however, the extent of such changes in triticale is not yet understood. In the present study, metAFLP, a variation of methylation-sensitive amplified fragment length polymorphism analysis, was used to investigate tissue culture-induced variation in triticale regenerants derived from four distinct genotypes using androgenesis and somatic embryogenesis. The metAFLP technique enabled identification of both sequence and DNA methylation pattern changes in a single experiment. Moreover, it was possible to quantify subtle effects such as sequence variation, demethylation, and de novo methylation, which affected 19, 5.5, 4.5% of sites, respectively. Comparison of variation in different genotypes and with different in vitro regeneration approaches demonstrated that both the culture technique and genetic background of donor plants affected tissue culture-induced variation. The results showed that the metAFLP approach could be used for quantification of tissue culture-induced variation and provided direct evidence that in vitro plant regeneration could cause genetic and epigenetic variation.

Dopa decarboxylase (Ddc) affects variation in Drosophila longevity.

PubMed

De Luca, Maria; Roshina, Nataliya V; Geiger-Thornsberry, Gretchen L; Lyman, Richard F; Pasyukova, Elena G; Mackay, Trudy F C

2003-08-01

Mutational analyses in model organisms have shown that genes affecting metabolism and stress resistance regulate life span, but the genes responsible for variation in longevity in natural populations are largely unidentified. Previously, we mapped quantitative trait loci (QTLs) affecting variation in longevity between two Drosophila melanogaster strains. Here, we show that the longevity QTL in the 36E;38B cytogenetic interval on chromosome 2 contains multiple closely linked QTLs, including the Dopa decarboxylase (Ddc) locus. Complementation tests to mutations show that Ddc is a positional candidate gene for life span in these strains. Linkage disequilibrium (LD) mapping in a sample of 173 alleles from a single population shows that three common molecular polymorphisms in Ddc account for 15.5% of the genetic contribution to variance in life span from chromosome 2. The polymorphisms are in strong LD, and the effects of the haplotypes on longevity suggest that the polymorphisms are maintained by balancing selection. DDC catalyzes the final step in the synthesis of the neurotransmitters, dopamine and serotonin. Thus, these data implicate variation in the synthesis of bioamines as a factor contributing to natural variation in individual life span.

CRHR1 genotypes, neural circuits and the diathesis for anxiety and depression.

PubMed

Rogers, J; Raveendran, M; Fawcett, G L; Fox, A S; Shelton, S E; Oler, J A; Cheverud, J; Muzny, D M; Gibbs, R A; Davidson, R J; Kalin, N H

2013-06-01

The corticotrophin-releasing hormone (CRH) system integrates the stress response and is associated with stress-related psychopathology. Previous reports have identified interactions between childhood trauma and sequence variation in the CRH receptor 1 gene (CRHR1) that increase risk for affective disorders. However, the underlying mechanisms that connect variation in CRHR1 to psychopathology are unknown. To explore potential mechanisms, we used a validated rhesus macaque model to investigate association between genetic variation in CRHR1, anxious temperament (AT) and brain metabolic activity. In young rhesus monkeys, AT is analogous to the childhood risk phenotype that predicts the development of human anxiety and depressive disorders. Regional brain metabolism was assessed with (18)F-labeled fluoro-2-deoxyglucose (FDG) positron emission tomography in 236 young, normally reared macaques that were also characterized for AT. We show that single nucleotide polymorphisms (SNPs) affecting exon 6 of CRHR1 influence both AT and metabolic activity in the anterior hippocampus and amygdala, components of the neural circuit underlying AT. We also find evidence for association between SNPs in CRHR1 and metabolism in the intraparietal sulcus and precuneus. These translational data suggest that genetic variation in CRHR1 affects the risk for affective disorders by influencing the function of the neural circuit underlying AT and that differences in gene expression or the protein sequence involving exon 6 may be important. These results suggest that variation in CRHR1 may influence brain function before any childhood adversity and may be a diathesis for the interaction between CRHR1 genotypes and childhood trauma reported to affect human psychopathology.

Foliar Nitrogen and Potassium Variation in Cottonwood as Affected by Genetic and Site Factors

Treesearch

James B. Baker; W. K. Randall

1975-01-01

Genetic and soil factors accounted for 49 percent of the variation in foliar N and 60 percent of the variation in foliar K among four good and four poor cottonwood clones grown on productive and unproductive soils in Mississippi. Variation in foliar N was associated primarily with the clone X soil interaction; variation in foliar K was related chiefly to clonal...

Spatiotemporal variation in deer browse and tolerance in a woodland herb

Treesearch

Holly R. Prendeville; Janet C. Steven; Laura F. Galloway

2015-01-01

Herbivory can shape the dynamics of plant populations, including effects on survival and reproduction, and is in turn affected by environmental factors that vary in space and time. White-tailed deer are significant herbivores in North America that have been broadly documented to affect plant reproductive success. If variation in the frequency and impact of herbivory by...

Variation in flooding-induced morphological traits in natural populations of white clover (Trifolium repens) and their effects on plant performance during soil flooding

PubMed Central

Huber, Heidrun; Jacobs, Elke; Visser, Eric J. W.

2009-01-01

Background and Aims Soil flooding leads to low soil oxygen concentrations and thereby negatively affects plant growth. Differences in flooding tolerance have been explained by the variation among species in the extent to which traits related to acclimation were expressed. However, our knowledge of variation within natural species (i.e. among individual genotypes) in traits related to flooding tolerance is very limited. Such data could tell us on which traits selection might have taken place, and will take place in future. The aim of the present study was to show that variation in flooding-tolerance-related traits is present among genotypes of the same species, and that both the constitutive variation and the plastic variation in flooding-induced changes in trait expression affect the performance of genotypes during soil flooding. Methods Clones of Trifolium repens originating from a river foreland were subjected to either drained, control conditions or to soil flooding. Constitutive expression of morphological traits was recorded on control plants, and flooding-induced changes in expression were compared with these constitutive expression levels. Moreover, the effect of both constitutive and flooding-induced trait expression on plant performance was determined. Key Results Constitutive and plastic variation of several morphological traits significantly affected plant performance. Even relatively small increases in root porosity and petiole length contributed to better performance during soil flooding. High specific leaf area, by contrast, was negatively correlated with performance during flooding. Conclusions The data show that different genotypes responded differently to soil flooding, which could be linked to variation in morphological trait expression. As flooded and drained conditions exerted different selection pressures on trait expression, the optimal value for constitutive and plastic traits will depend on the frequency and duration of flooding. These data will help us understanding the mechanisms affecting short- and long-term dynamics in flooding-prone ecosystems. PMID:18713824

Genetic divergence in nuclear genomes between populations of Fagus crenata along the Japan Sea and Pacific sides of Japan.

PubMed

Hiraoka, Koichi; Tomaru, Nobuhiro

2009-05-01

Genetic diversity and structure in Fagus crenata were studied by analyzing 14 nuclear microsatellite loci in 23 populations distributed throughout the species' range. Although population differentiation was very low (F (ST) = 0.027; R (ST) = 0.041), both neighbor-joining tree and Bayesian clustering analyses provided clear evidence of genetic divergence between populations along the Japan Sea (Japan Sea lineage) and Pacific (Pacific lineage) sides of Japan, indicating that physical barriers to migration and gene flow, notably the mountain ranges separating the populations along the Japan Sea and Pacific sides, have promoted genetic divergence between these populations. The two lineages of the nuclear genome are generally consistent with those of the chloroplast genome detected in a previous study, with several discrepancies between the two genomes. Within-population genetic diversity was generally very high (average H (E) = 0.839), but decreased in a clinal fashion from southwest to northeast, largely among populations of the Japan Sea lineage. This geographical gradient may have resulted from the late-glacial and postglacial recolonization to the northeast, which led to a loss of within-population genetic diversity due to cumulative founder effects.

Pluck or Luck: Does Trait Variation or Chance Drive Variation in Lifetime Reproductive Success?

PubMed

Snyder, Robin E; Ellner, Stephen P

2018-04-01

While there has been extensive interest in how intraspecific trait variation affects ecological processes, outcomes are highly variable even when individuals are identical: some are lucky, while others are not. Trait variation is therefore important only if it adds substantially to the variability produced by luck. We ask when trait variation has a substantial effect on variability in lifetime reproductive success (LRS), using two approaches: (1) we partition the variation in LRS into contributions from luck and trait variation and (2) we ask what can be inferred about an individual's traits and with what certainty, given their observed LRS. In theoretical stage- and size-structured models and two empirical case studies, we find that luck usually dominates the variance of LRS. Even when individuals differ substantially in ways that affect expected LRS, unless the effects of luck are substantially reduced (e.g., low variability in reproductive life span or annual fecundity), most variance in lifetime outcomes is due to luck, implying that departures from "null" models omitting trait variation will be hard to detect. Luck also obscures the relationship between realized LRS and individual traits. While trait variation may influence the fate of populations, luck often governs the lives of individuals.

Links between Natural Variation in the Microbiome and Host Fitness in Wild Mammals.

PubMed

Suzuki, Taichi A

2017-10-01

Recent studies in model organisms have shown that compositional variation in the microbiome can affect a variety of host phenotypes including those related to digestion, development, immunity, and behavior. Natural variation in the microbiome within and between natural populations and species may also affect host phenotypes and thus fitness in the wild. Here, I review recent evidence that compositional variation in the microbiome may affect host phenotypes and fitness in wild mammals. Studies over the last decade indicate that natural variation in the mammalian microbiome may be important in the assistance of energy uptake from different diet types, detoxification of plant secondary compounds, protection from pathogens, chemical communication, and behavior. I discuss the importance of combining both field observations and manipulative experiments in a single system to fully characterize the functions and fitness effects of the microbiome. Finally, I discuss the evolutionary consequences of mammal-microbiome associations by proposing a framework to test how natural selection on hosts is mediated by the microbiome. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Unravelling variation in feeding, social interaction and growth patterns among pigs using an agent-based model.

PubMed

Boumans, Iris J M M; de Boer, Imke J M; Hofstede, Gert Jan; Bokkers, Eddie A M

2018-07-01

Domesticated pigs, Sus scrofa, vary considerably in feeding, social interaction and growth patterns. This variation originates partly from genetic variation that affects physiological factors and partly from behavioural strategies (avoid or approach) in competitive food resource situations. Currently, it is unknown how variation in physiological factors and in behavioural strategies among animals contributes to variation in feeding, social interaction and growth patterns in animals. The aim of this study was to unravel causation of variation in these patterns among pigs. We used an agent-based model to explore the effects of physiological factors and behavioural strategies in pigs on variation in feeding, social interaction and growth patterns. Model results show that variation in feeding, social interaction and growth patterns are caused partly by chance, such as time effects and coincidence of conflicts. Furthermore, results show that seemingly contradictory empirical findings in literature can be explained by variation in pig characteristics (i.e. growth potential, positive feedback, dominance, and coping style). Growth potential mainly affected feeding and growth patterns, whereas positive feedback, dominance and coping style affected feeding patterns, social interaction patterns, as well as growth patterns. Variation in behavioural strategies among pigs can reduce aggression at group level, but also make some pigs more susceptible to social constraints inhibiting them from feeding when they want to, especially low-ranking pigs and pigs with a passive coping style. Variation in feeding patterns, such as feeding rate or meal frequency, can indicate social constraints. Feeding patterns, however, can say something different about social constraints at group versus individual level. A combination of feeding patterns, such as a decreased feed intake, an increased feeding rate, and an increased meal frequency might, therefore, be needed to measure social constraints at individual level. Copyright © 2018 Elsevier Inc. All rights reserved.

Genetic variation in adaptability and pleiotropy in budding yeast

PubMed Central

Mitchell, James Kameron; Bloom, Joshua S; Kruglyak, Leonid

2017-01-01

Evolution can favor organisms that are more adaptable, provided that genetic variation in adaptability exists. Here, we quantify this variation among 230 offspring of a cross between diverged yeast strains. We measure the adaptability of each offspring genotype, defined as its average rate of adaptation in a specific environmental condition, and analyze the heritability, predictability, and genetic basis of this trait. We find that initial genotype strongly affects adaptability and can alter the genetic basis of future evolution. Initial genotype also affects the pleiotropic consequences of adaptation for fitness in a different environment. This genetic variation in adaptability and pleiotropy is largely determined by initial fitness, according to a rule of declining adaptability with increasing initial fitness, but several individual QTLs also have a significant idiosyncratic role. Our results demonstrate that both adaptability and pleiotropy are complex traits, with extensive heritable differences arising from naturally occurring variation. PMID:28826486

Genetic variation in adaptability and pleiotropy in budding yeast.

PubMed

Jerison, Elizabeth R; Kryazhimskiy, Sergey; Mitchell, James Kameron; Bloom, Joshua S; Kruglyak, Leonid; Desai, Michael M

2017-08-17

Evolution can favor organisms that are more adaptable, provided that genetic variation in adaptability exists. Here, we quantify this variation among 230 offspring of a cross between diverged yeast strains. We measure the adaptability of each offspring genotype, defined as its average rate of adaptation in a specific environmental condition, and analyze the heritability, predictability, and genetic basis of this trait. We find that initial genotype strongly affects adaptability and can alter the genetic basis of future evolution. Initial genotype also affects the pleiotropic consequences of adaptation for fitness in a different environment. This genetic variation in adaptability and pleiotropy is largely determined by initial fitness, according to a rule of declining adaptability with increasing initial fitness, but several individual QTLs also have a significant idiosyncratic role. Our results demonstrate that both adaptability and pleiotropy are complex traits, with extensive heritable differences arising from naturally occurring variation.

Dynamic extrafloral nectar production: the timing of leaf damage affects the defensive response in Senna mexicana var. chapmanii (Fabaceae).

PubMed

Jones, Ian M; Koptur, Suzanne

2015-01-01

• Extrafloral nectar (EFN) mediates food for protection mutualisms between plants and defensive insects. Understanding sources of variation in EFN production is important because such variations may affect the number and identity of visitors and the effectiveness of plant defense. We investigated the influence of plant developmental stage, time of day, leaf age, and leaf damage on EFN production in Senna mexicana var. chapmanii. The observed patterns of variation in EFN production were compared with those predicted by optimal defense theory.• Greenhouse experiments with potted plants were conducted to determine how plant age, time of day, and leaf damage affected EFN production. A subsequent field study was conducted to determine how leaf damage, and the resulting increase in EFN production, affected ant visitation in S. chapmanii.• More nectar was produced at night and by older plants. Leaf damage resulted in increased EFN production, and the magnitude of the response was greater in plants damaged in the morning than those damaged at night. Damage to young leaves elicited a stronger defensive response than damage to older leaves, in line with optimal defense theory. Damage to the leaves of S. chapmanii also resulted in significantly higher ant visitation in the field.• Extrafloral nectar is an inducible defense in S. chapmanii. Developmental variations in its production support the growth differentiation balance hypothesis, while within-plant variations and damage responses support optimal defense theory. © 2015 Botanical Society of America, Inc.

OXTR polymorphism predicts social relationships through its effects on social temperament

PubMed Central

Wright, Aidan G. C.; Troxel, Wendy M.; Ferrell, Robert E.; Flory, Janine D.; Manuck, Stephen B.

2015-01-01

Humans have a fundamental need for strong interpersonal bonds, yet individuals differ appreciably in their degree of social integration. That these differences are also substantially heritable has spurred interest in biological mechanisms underlying the quality and quantity of individuals’ social relationships. We propose that polymorphic variation in the oxytocin receptor gene (OXTR) associates with complex social behaviors and social network composition through intermediate effects on negative affectivity and the psychological processing of socially relevant information. We tested a hypothesized social cascade from the molecular level (OXTR variation) to the social environment, through negative affectivity and inhibited sociality, in a sample of 1295 men and women of European American (N = 1081) and African American (N = 214) ancestry. Compared to European Americans having any T allele of rs1042778, individuals homozygous for the alternate G allele reported significantly lower levels of negative affectivity and inhibited sociality, which in turn predicted significantly higher levels of social support and a larger/more diverse social network. Moreover, the effect of rs1042778 variation on social support was fully accounted for by associated differences in negative affectivity and inhibited sociality. Results replicated in the African American sample. Findings suggest that OXTR variation modulates levels of social support via proximal impacts on individual temperament. PMID:25326040

Germanium soup

NASA Astrophysics Data System (ADS)

Palmer, Troy A.; Alexay, Christopher C.

2006-05-01

This paper addresses the variety and impact of dispersive model variations for infrared materials and, in particular, the level to which certain optical designs are affected by this potential variation in germanium. This work offers a method for anticipating and/or minimizing the pitfalls such potential model variations may have on a candidate optical design.

Social Anxiety Modulates Subliminal Affective Priming

PubMed Central

Paul, Elizabeth S.; Pope, Stuart A. J.; Fennell, John G.; Mendl, Michael T.

2012-01-01

Background It is well established that there is anxiety-related variation between observers in the very earliest, pre-attentive stage of visual processing of images such as emotionally expressive faces, often leading to enhanced attention to threat in a variety of disorders and traits. Whether there is also variation in early-stage affective (i.e. valenced) responses resulting from such images, however, is not yet known. The present study used the subliminal affective priming paradigm to investigate whether people varying in trait social anxiety also differ in their affective responses to very briefly presented, emotionally expressive face images. Methodology/Principal Findings Participants (n = 67) completed a subliminal affective priming task, in which briefly presented and smiling, neutral and angry faces were shown for 10 ms durations (below objective and subjective thresholds for visual discrimination), and immediately followed by a randomly selected Chinese character mask (2000 ms). Ratings of participants' liking for each Chinese character indicated the degree of valenced affective response made to the unseen emotive images. Participants' ratings of their liking for the Chinese characters were significantly influenced by the type of face image preceding them, with smiling faces generating more positive ratings than neutral and angry ones (F(2,128) = 3.107, p<0.05). Self-reported social anxiety was positively correlated with ratings of smiling relative to neutral-face primed characters (Pearson's r = .323, p<0.01). Individual variation in self-reported mood awareness was not associated with ratings. Conclusions Trait social anxiety is associated with individual variation in affective responding, even in response to the earliest, pre-attentive stage of visual image processing. However, the fact that these priming effects are limited to smiling and not angry (i.e. threatening) images leads us to propose that the pre-attentive processes involved in generating the subliminal affective priming effect may be different from those that generate attentional biases in anxious individuals. PMID:22615873

Social anxiety modulates subliminal affective priming.

PubMed

Paul, Elizabeth S; Pope, Stuart A J; Fennell, John G; Mendl, Michael T

2012-01-01

It is well established that there is anxiety-related variation between observers in the very earliest, pre-attentive stage of visual processing of images such as emotionally expressive faces, often leading to enhanced attention to threat in a variety of disorders and traits. Whether there is also variation in early-stage affective (i.e. valenced) responses resulting from such images, however, is not yet known. The present study used the subliminal affective priming paradigm to investigate whether people varying in trait social anxiety also differ in their affective responses to very briefly presented, emotionally expressive face images. Participants (n = 67) completed a subliminal affective priming task, in which briefly presented and smiling, neutral and angry faces were shown for 10 ms durations (below objective and subjective thresholds for visual discrimination), and immediately followed by a randomly selected Chinese character mask (2000 ms). Ratings of participants' liking for each Chinese character indicated the degree of valenced affective response made to the unseen emotive images. Participants' ratings of their liking for the Chinese characters were significantly influenced by the type of face image preceding them, with smiling faces generating more positive ratings than neutral and angry ones (F(2,128) = 3.107, p<0.05). Self-reported social anxiety was positively correlated with ratings of smiling relative to neutral-face primed characters (Pearson's r = .323, p<0.01). Individual variation in self-reported mood awareness was not associated with ratings. Trait social anxiety is associated with individual variation in affective responding, even in response to the earliest, pre-attentive stage of visual image processing. However, the fact that these priming effects are limited to smiling and not angry (i.e. threatening) images leads us to propose that the pre-attentive processes involved in generating the subliminal affective priming effect may be different from those that generate attentional biases in anxious individuals.

Tree-to-tree variation in seed size and its consequences for seed dispersal versus predation by rodents.

PubMed

Wang, Bo; Ives, Anthony R

2017-03-01

Individual variation in seed size and seed production is high in many plant species. How does this variation affect seed-dispersing animals and, in turn, the fitness of individual plants? In this study, we first surveyed intraspecific variation in seed mass and production in a population of a Chinese white pine, Pinus armandii. For 134 target trees investigated in 2012, there was very high variation in seed size, with mean seed mass varying among trees almost tenfold, from 0.038 to 0.361 g. Furthermore, 30 of the 134 trees produced seeds 2 years later, and for these individuals there was a correlation in seed mass of 0.59 between years, implying consistent differences among individuals. For a subset of 67 trees, we monitored the foraging preferences of scatter-hoarding rodents on a total of 15,301 seeds: 8380 were ignored, 3184 were eaten in situ, 2651 were eaten after being cached, and 395 were successfully dispersed (cached and left intact). At the scale of individual seeds, seed mass affected almost every decision that rodents made to eat, remove, and cache individual seeds. At the level of individual trees, larger seeds had increased probabilities of both predation and successful dispersal: the effects of mean seed size on costs (predation) and benefits (caching) balanced out. Thus, despite seed size affecting rodent decisions, variation among trees in dispersal success associated with mean seed size was small once seeds were harvested. This might explain, at least in part, the maintenance of high variation in mean seed mass among tree individuals.

Female fecundity variation affects reproducibility of experiments on host plant preference and acceptance in a phytophagous insect

PubMed Central

Schäpers, Alexander; Petrén, Hampus; Wheat, Christopher W.; Wiklund, Christer

2017-01-01

Reproducibility is a scientific cornerstone. Many recent studies, however, describe a reproducibility crisis and call for assessments of reproducibility across scientific domains. Here, we explore the reproducibility of a classic ecological experiment—that of assessing female host plant preference and acceptance in phytophagous insects, a group in which host specialization is a key driver of diversification. We exposed multiple cohorts of Pieris napi butterflies from the same population to traditional host acceptance and preference tests on three Brassicaceae host species. Whereas the host plant rank order was highly reproducible, the propensity to oviposit on low-ranked hosts varied significantly even among cohorts exposed to similar conditions. Much variation could be attributed to among-cohort variation in female fecundity, a trait strongly correlated both to female size and to the size of the nuptial gift a female receives during mating. Small males provide small spermatophores, and in our experiment small females that mated with small males had a disproportionally low propensity to oviposit on low-ranked hosts. Hence, our results provide empirical support to the theoretical prediction that female host utilization is strongly affected by non-genetic, environmental variation, and that such variation can affect the reproducibility of ecological experiments even under seemingly identical conditions. PMID:28202813

Genetic by environment interactions affect plant–soil linkages

PubMed Central

Pregitzer, Clara C; Bailey, Joseph K; Schweitzer, Jennifer A

2013-01-01

The role of plant intraspecific variation in plant–soil linkages is poorly understood, especially in the context of natural environmental variation, but has important implications in evolutionary ecology. We utilized three 18- to 21-year-old common gardens across an elevational gradient, planted with replicates of five Populus angustifolia genotypes each, to address the hypothesis that tree genotype (G), environment (E), and G × E interactions would affect soil carbon and nitrogen dynamics beneath individual trees. We found that soil nitrogen and carbon varied by over 50% and 62%, respectively, across all common garden environments. We found that plant leaf litter (but not root) traits vary by genotype and environment while soil nutrient pools demonstrated genotype, environment, and sometimes G × E interactions, while process rates (net N mineralization and net nitrification) demonstrated G × E interactions. Plasticity in tree growth and litter chemistry was significantly related to the variation in soil nutrient pools and processes across environments, reflecting tight plant–soil linkages. These data overall suggest that plant genetic variation can have differential affects on carbon storage and nitrogen cycling, with implications for understanding the role of genetic variation in plant–soil feedback as well as management plans for conservation and restoration of forest habitats with a changing climate. PMID:23919173

Human germline and pan-cancer variomes and their distinct functional profiles

PubMed Central

Pan, Yang; Karagiannis, Konstantinos; Zhang, Haichen; Dingerdissen, Hayley; Shamsaddini, Amirhossein; Wan, Quan; Simonyan, Vahan; Mazumder, Raja

2014-01-01

Identification of non-synonymous single nucleotide variations (nsSNVs) has exponentially increased due to advances in Next-Generation Sequencing technologies. The functional impacts of these variations have been difficult to ascertain because the corresponding knowledge about sequence functional sites is quite fragmented. It is clear that mapping of variations to sequence functional features can help us better understand the pathophysiological role of variations. In this study, we investigated the effect of nsSNVs on more than 17 common types of post-translational modification (PTM) sites, active sites and binding sites. Out of 1 705 285 distinct nsSNVs on 259 216 functional sites we identified 38 549 variations that significantly affect 10 major functional sites. Furthermore, we found distinct patterns of site disruptions due to germline and somatic nsSNVs. Pan-cancer analysis across 12 different cancer types led to the identification of 51 genes with 106 nsSNV affected functional sites found in 3 or more cancer types. 13 of the 51 genes overlap with previously identified Significantly Mutated Genes (Nature. 2013 Oct 17;502(7471)). 62 mutations in these 13 genes affecting functional sites such as DNA, ATP binding and various PTM sites occur across several cancers and can be prioritized for additional validation and investigations. PMID:25232094

GLACE: The Global Land-Atmosphere Coupling Experiment Part 2: Analysis

NASA Technical Reports Server (NTRS)

Guo, Zhichang; Dirmeyer, Paul A.; Koster, Randal D.; Bonan, Gordon; Chan, Edmond; Cox, Peter; Gordon, C. T.; Kanae, Shinjiro; Kowalczyk, Eva; Lawrence, David

2005-01-01

The twelve weather and climate models participating in the Global Land-Atmosphere Coupling Experiment (GLACE) show both a wide variation in the strength of land-atmosphere coupling and some intriguing commonalities. In this paper, we address the causes of variations in coupling strength - both the geographic variations within a given model and the model-to-model differences. The ability of soil moisture to affect precipitation is examined in two stages, namely, the ability of the soil moisture to affect evaporation, and the ability of evaporation to affect precipitation. Most of the differences between the models and within a given model are found to be associated with the first stage - an evaporation rate that varies strongly and consistently with soil moisture tends to lead to a higher coupling strength. The first stage differences reflect identifiable differences in model parameterization and model climate. Intermodel differences in the evaporation-precipitation connection, however, also play a key role.

Understanding Heterogeneity in the Effects of Birth Weight on Adult Cognition and Wages

PubMed Central

Cook, C. Justin; Fletcher, Jason M.

2015-01-01

A large economics literature has shown long term impacts of birth weight on adult outcomes, including IQ and earnings that are often robust to sibling or twin fixed effects. We examine potential mechanisms underlying these effects by incorporating findings from the genetics and neuroscience literatures. We use a sample of siblings combined with an “orchids and dandelions hypothesis”, where the IQ of genetic dandelions is not affected by in utero nutrition variation but genetic orchids thrive under advantageous conditions and wilt in poor conditions. Indeed, using variation in three candidate genes related to neuroplasticity (APOE, BDNF, and COMT), we find substantial heterogeneity in the associations between birth weight and adult outcomes, where part of the population (i.e., “dandelions”) is not affected by birth weight variation. Our results help uncover why birth weight affects adult outcomes. PMID:25770970

Understanding heterogeneity in the effects of birth weight on adult cognition and wages.

PubMed

Justin Cook, C; Fletcher, Jason M

2015-05-01

A large economics literature has shown long term impacts of birth weight on adult outcomes, including IQ and earnings that are often robust to sibling or twin fixed effects. We examine potential mechanisms underlying these effects by incorporating findings from the genetics and neuroscience literatures. We use a sample of siblings combined with an "orchids and dandelions hypothesis", where the IQ of genetic dandelions is not affected by in utero nutrition variation but genetic orchids thrive under advantageous conditions and wilt in poor conditions. Indeed, using variation in three candidate genes related to neuroplasticity (APOE, BDNF, and COMT), we find substantial heterogeneity in the associations between birth weight and adult outcomes, where part of the population (i.e., "dandelions") is not affected by birth weight variation. Our results help uncover why birth weight affects adult outcomes. Copyright © 2015 Elsevier B.V. All rights reserved.

Genetic variation in serotonin transporter function affects human fear expression indexed by fear-potentiated startle.

PubMed

Klumpers, Floris; Heitland, Ivo; Oosting, Ronald S; Kenemans, J Leon; Baas, Johanna M P

2012-02-01

The serotonin transporter (SERT) plays a crucial role in anxiety. Accordingly, variance in SERT functioning appears to constitute an important pathway to individual differences in anxiety. The current study tested the hypothesis that genetic variation in SERT function is associated with variability in the basic reflex physiology of defense. Healthy subjects (N=82) were presented with clearly instructed cues of shock threat and safety to induce robust anxiety reactions. Subjects carrying at least one short allele for the 5-HTTLPR polymorphism showed stronger fear-potentiated startle compared to long allele homozygotes. However, short allele carriers showed no deficit in the downregulation of fear after the offset of threat. These results suggest that natural variation in SERT function affects the magnitude of defensive reactions while not affecting the capacity for fear regulation. Copyright © 2011 Elsevier B.V. All rights reserved.

A study on parameter variation effects on battery packs for electric vehicles

NASA Astrophysics Data System (ADS)

Zhou, Long; Zheng, Yuejiu; Ouyang, Minggao; Lu, Languang

2017-10-01

As one single cell cannot meet power and driving range requirement in an electric vehicle, the battery packs with hundreds of single cells connected in parallel and series should be constructed. The most significant difference between a single cell and a battery pack is cell variation. Not only does cell variation affect pack energy density and power density, but also it causes early degradation of battery and potential safety issues. The cell variation effects on battery packs are studied, which are of great significant to battery pack screening and management scheme. In this study, the description for the consistency characteristics of battery packs was first proposed and a pack model with 96 cells connected in series was established. A set of parameters are introduced to study the cell variation and their impacts on battery packs are analyzed through the battery pack capacity loss simulation and experiments. Meanwhile, the capacity loss composition of the battery pack is obtained and verified by the temperature variation experiment. The results from this research can demonstrate that the temperature, self-discharge rate and coulombic efficiency are the major affecting parameters of cell variation and indicate the dissipative cell equalization is sufficient for the battery pack.

Focus on Teacher Salaries: What Teacher Salary Averages Don't Show.

ERIC Educational Resources Information Center

Gaines, Gale

Traditional comparisons of teacher salary averages fail to consider factors beyond pay raises that affect those averages. Salary averages do not show: regional and national variations among states' average salaries; the variation of salaries within an individual state; variations in the cost of living; the highest degree earned by teachers and the…

Subtelomeric Rearrangements and Copy Number Variations in People with Intellectual Disabilities

ERIC Educational Resources Information Center

Christofolini, D. M.; De Paula Ramos, M. A.; Kulikowski, L. D.; Da Silva Bellucco, F. T.; Belangero, S. I. N.; Brunoni, D.; Melaragno, M. I.

2010-01-01

Background: The most prevalent type of structural variation in the human genome is represented by copy number variations that can affect transcription levels, sequence, structure and function of genes. Method: In the present study, we used the multiplex ligation-dependent probe amplification (MLPA) technique and quantitative PCR for the detection…

The Effects of Environmental Characteristics on the Structure of Hospital Clusters.

ERIC Educational Resources Information Center

Fennell, Mary L.

1980-01-01

The population ecology view that variation in sets or clusters of organizations should be isomorphic with variation in cluster environment was used to explain structural variation among hospital clusters. Cluster differentiation seems to be casually affected by range of services, average hospital size, and the periodic closing of hospitals.…

Effects of Wolbachia on mitochondrial DNA variation in populations of Athetis lepigone (Lepidoptera: Noctuidae) in China

USDA-ARS?s Scientific Manuscript database

Wolbachia are endosymbiotic bacteria that infect arthropods and incompatibility among strains can affect gene flow within host insect populations, that can result in significant host mitochondrial DNA (MtD) variation. The effects of Wolbachia infection on mtDNA variation was studied in Athetis lepi...

Genetic studies of African populations: an overview on disease susceptibility and response to vaccines and therapeutics.

PubMed

Sirugo, Giorgio; Hennig, Branwen J; Adeyemo, Adebowale A; Matimba, Alice; Newport, Melanie J; Ibrahim, Muntaser E; Ryckman, Kelli K; Tacconelli, Alessandra; Mariani-Costantini, Renato; Novelli, Giuseppe; Soodyall, Himla; Rotimi, Charles N; Ramesar, Raj S; Tishkoff, Sarah A; Williams, Scott M

2008-07-01

Africa is the ultimate source of modern humans and as such harbors more genetic variation than any other continent. For this reason, studies of the patterns of genetic variation in African populations are crucial to understanding how genes affect phenotypic variation, including disease predisposition. In addition, the patterns of extant genetic variation in Africa are important for understanding how genetic variation affects infectious diseases that are a major problem in Africa, such as malaria, tuberculosis, schistosomiasis, and HIV/AIDS. Therefore, elucidating the role that genetic susceptibility to infectious diseases plays is critical to improving the health of people in Africa. It is also of note that recent and ongoing social and cultural changes in sub-Saharan Africa have increased the prevalence of non-communicable diseases that will also require genetic analyses to improve disease prevention and treatment. In this review we give special attention to many of the past and ongoing studies, emphasizing those in Sub-Saharan Africans that address the role of genetic variation in human disease.

Distribution, functional impact, and origin mechanisms of copy number variation in the barley genome

PubMed Central

2013-01-01

Background There is growing evidence for the prevalence of copy number variation (CNV) and its role in phenotypic variation in many eukaryotic species. Here we use array comparative genomic hybridization to explore the extent of this type of structural variation in domesticated barley cultivars and wild barleys. Results A collection of 14 barley genotypes including eight cultivars and six wild barleys were used for comparative genomic hybridization. CNV affects 14.9% of all the sequences that were assessed. Higher levels of CNV diversity are present in the wild accessions relative to cultivated barley. CNVs are enriched near the ends of all chromosomes except 4H, which exhibits the lowest frequency of CNVs. CNV affects 9.5% of the coding sequences represented on the array and the genes affected by CNV are enriched for sequences annotated as disease-resistance proteins and protein kinases. Sequence-based comparisons of CNV between cultivars Barke and Morex provided evidence that DNA repair mechanisms of double-strand breaks via single-stranded annealing and synthesis-dependent strand annealing play an important role in the origin of CNV in barley. Conclusions We present the first catalog of CNVs in a diploid Triticeae species, which opens the door for future genome diversity research in a tribe that comprises the economically important cereal species wheat, barley, and rye. Our findings constitute a valuable resource for the identification of CNV affecting genes of agronomic importance. We also identify potential mechanisms that can generate variation in copy number in plant genomes. PMID:23758725

Genetic Brain Disorders

MedlinePlus

A genetic brain disorder is caused by a variation or a mutation in a gene. A variation is a different form ... mutation is a change in a gene. Genetic brain disorders affect the development and function of the ...

Making quantitative morphological variation from basic developmental processes: where are we? The case of the Drosophila wing

PubMed Central

Alexis, Matamoro-Vidal; Isaac, Salazar-Ciudad; David, Houle

2015-01-01

One of the aims of evolutionary developmental biology is to discover the developmental origins of morphological variation. The discipline has mainly focused on qualitative morphological differences (e.g., presence or absence of a structure) between species. Studies addressing subtle, quantitative variation are less common. The Drosophila wing is a model for the study of development and evolution, making it suitable to investigate the developmental mechanisms underlying the subtle quantitative morphological variation observed in nature. Previous reviews have focused on the processes involved in wing differentiation, patterning and growth. Here, we investigate what is known about how the wing achieves its final shape, and what variation in development is capable of generating the variation in wing shape observed in nature. Three major developmental stages need to be considered: larval development, pupariation, and pupal development. The major cellular processes involved in the determination of tissue size and shape are cell proliferation, cell death, oriented cell division and oriented cell intercalation. We review how variation in temporal and spatial distribution of growth and transcription factors affects these cellular mechanisms, which in turn affects wing shape. We then discuss which aspects of the wing morphological variation are predictable on the basis of these mechanisms. PMID:25619644

Variations in 5-HTTLPR: relation to familiar risk of affective disorder, life events, neuroticism and cortisol.

PubMed

Vinberg, Maj; Mellerup, Erling; Andersen, Per Kragh; Bennike, Bente; Kessing, Lars Vedel

2010-02-01

Variations in the serotonin transporter gene (5-HTTLPR) and stressful life events are associated with affective disorders. To investigate whether the distribution of the alleles of the 5-HTTLPR is associated with a genetic predisposition to affective disorder and whether these variations interact with life events in relation to depressive symptoms, neuroticism and salivary cortisol. In a high-risk population study, healthy monozygotic and dizygotic twins with (high-risk twins) and without (low-risk twins) a co-twin history of affective disorder were identified through nationwide registers. When comparing the 81 individuals homozygote for the long allele with the 125 individuals hetero- and homozygote for the short allele no associations between the allele distribution and a genetic predisposition were found. The presence of the short allele of the 5-HTTLPR and the experience of SLE was associated with a higher neuroticism score, but not with depressive symptoms nor awakening or evening salivary cortisol. A combination of variants in 5-HTTLPR and environmental stress seems to increase neuroticism in healthy individuals. Copyright 2009 Elsevier Inc. All rights reserved.

Genetic mapping of variation in dauer larvae development in growing populations of Caenorhabditis elegans.

PubMed

Green, J W M; Snoek, L B; Kammenga, J E; Harvey, S C

2013-10-01

In the nematode Caenorhabditis elegans, the appropriate induction of dauer larvae development within growing populations is likely to be a primary determinant of genotypic fitness. The underlying genetic architecture of natural genetic variation in dauer formation has, however, not been thoroughly investigated. Here, we report extensive natural genetic variation in dauer larvae development within growing populations across multiple wild isolates. Moreover, bin mapping of introgression lines (ILs) derived from the genetically divergent isolates N2 and CB4856 reveals 10 quantitative trait loci (QTLs) affecting dauer formation. Comparison of individual ILs to N2 identifies an additional eight QTLs, and sequential IL analysis reveals six more QTLs. Our results also show that a behavioural, laboratory-derived, mutation controlled by the neuropeptide Y receptor homolog npr-1 can affect dauer larvae development in growing populations. These findings illustrate the complex genetic architecture of variation in dauer larvae formation in C. elegans and may help to understand how the control of variation in dauer larvae development has evolved.

Effect of Root-Zone Moisture Variations on Growth of Lettuce and Pea Plants

NASA Astrophysics Data System (ADS)

Ilieva, Iliana; Ivanova, Tania

2008-06-01

Variations in substrate moisture lead to changes in water and oxygen availability to plant roots. Ground experiments were carried out in the laboratory prototype of SVET-2 Space Greenhouse to study the effect of variation of root-zone moisture conditions on growth of lettuce and pea plants. The effect of transient increase (for 1 day) and drastic increase (waterlogging for 10 days) of substrate moisture was studied with 16-day old pea and 21-day old lettuce plants respectively. Pea height and fresh biomass accumulation were not affected by transient substrate moisture increase. Net photosynthetic rate (Pn) of pea plants showed fast response to substrate moisture variation, while chlorophyll content did not change. Drastic change of substrate moisture suppressed lettuce Pn, chlorophyll biosynthesis and plant growth. These parameters slowly recovered after termination of waterlogging treatment but lettuce yield was greatly affected. The results showed that the most sensitive physiological parameter to substrate moisture variations is photosynthesis.

Unexpected High Intragenomic Variation in Two of Three Major Pest Thrips Species Does Not Affect Ribosomal Internal Transcribed Spacer 2 (ITS2) Utility for Thrips Identification

PubMed Central

Dickey, Aaron M.; Seal, Dakshina R.; Shatters, Robert G.; Osborne, Lance S.; McKenzie, Cindy L.

2017-01-01

The mitochondrial cytochrome oxidase I gene (mtCO1) and the ribosomal internal transcribed spacer 2 region (ITS2) are among the most widely used molecular markers for insect taxonomic characterization. Three economically important species of thrips, Scirtothrips dorsalis, Thrips palmi, and Frankliniella occidentalis were selected to examine the extent of intragenomic variation within these two marker regions in the family Thripidae, and determine if this variation would affect the utility of markers in thrips molecular diagnostics. For each species, intragenomic (within individual) variation and intergenomic (among individuals) variation was assessed by cloning and sequencing PCR-amplified copies. Intergenomic variation was generally higher than intragenomic variation except in cases where intergenomic variation was very low, as in mtCO1 from S. dorsalis and F. occidentalis. Intragenomic variation was detected in both markers in all three of the thrips species, however, 2–3 times more intragenomic variation was observed for ITS2 than mtCO1 in both S. dorsalis and T. palmi. Furthermore, levels of intragenomic variation were low for both of the genes in F. occidentalis. In all of the three thrips species, no sex-based clustering of haplotypes was observed in either marker. Unexpected high intragenomic variation in ITS2 for two of three thrips species did not interfere with thrips diagnostics. However, caution should be taken in applying ITS2 to certain studies of S. dorsalis and T. palmi when high levels of intragenomic variation could be problematic or confounding. In such studies, mtCO1 may be a preferable marker. Possible reasons for discrepancies in intragenomic variation among genomic regions are discussed. PMID:28984819

Method for Reducing Pumping Damage to Blood

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Robert J. (Inventor); Benkowski, Robert J. (Inventor)

1997-01-01

Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed herein before. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

Factors associated with variation in financial condition among voluntary hospitals.

PubMed Central

Brecher, C; Nesbitt, S

1985-01-01

This article uses multiple regression analysis to identify factors which affect variations in the financial condition of voluntary hospitals in New York State. Six separate ratios are used to measure financial condition and 18 independent variables are considered. The factors affecting financial conditions were found to vary among dimensions of financial health, and different causal relationships were evident among hospitals in New York City than among those in the rest of the state. PMID:4019212

Comprehensive Evaluation of the Association of APOE Genetic Variation with Plasma Lipoprotein Traits in U.S. Whites and African Blacks

PubMed Central

Radwan, Zaheda H.; Wang, Xingbin; Waqar, Fahad; Pirim, Dilek; Niemsiri, Vipavee; Hokanson, John E.; Hamman, Richard F.; Bunker, Clareann H.; Barmada, M. Michael; Demirci, F. Yesim; Kamboh, M. Ilyas

2014-01-01

Although common APOE genetic variation has a major influence on plasma LDL-cholesterol, its role in affecting HDL-cholesterol and triglycerides is not well established. Recent genome-wide association studies suggest that APOE also affects plasma variation in HDL-cholesterol and triglycerides. It is thus important to resequence the APOE gene to identify both common and uncommon variants that affect plasma lipid profile. Here, we have sequenced the APOE gene in 190 subjects with extreme HDL-cholesterol levels selected from two well-defined epidemiological samples of U.S. non-Hispanic Whites (NHWs) and African Blacks followed by genotyping of identified variants in the entire datasets (623 NHWs, 788 African Blacks) and association analyses with major lipid traits. We identified a total of 40 sequence variants, of which 10 are novel. A total of 32 variants, including common tagSNPs (≥5% frequency) and all uncommon variants (<5% frequency) were successfully genotyped and considered for genotype-phenotype associations. Other than the established associations of APOE*2 and APOE*4 with LDL-cholesterol, we have identified additional independent associations with LDL-cholesterol. We have also identified multiple associations of uncommon and common APOE variants with HDL-cholesterol and triglycerides. Our comprehensive sequencing and genotype-phenotype analyses indicate that APOE genetic variation impacts HDL-cholesterol and triglycerides in addition to affecting LDL-cholesterol. PMID:25502880

OXTR polymorphism predicts social relationships through its effects on social temperament.

PubMed

Creswell, Kasey G; Wright, Aidan G C; Troxel, Wendy M; Ferrell, Robert E; Flory, Janine D; Manuck, Stephen B

2015-06-01

Humans have a fundamental need for strong interpersonal bonds, yet individuals differ appreciably in their degree of social integration. That these differences are also substantially heritable has spurred interest in biological mechanisms underlying the quality and quantity of individuals' social relationships. We propose that polymorphic variation in the oxytocin receptor gene (OXTR) associates with complex social behaviors and social network composition through intermediate effects on negative affectivity and the psychological processing of socially relevant information. We tested a hypothesized social cascade from the molecular level (OXTR variation) to the social environment, through negative affectivity and inhibited sociality, in a sample of 1295 men and women of European American (N = 1081) and African American (N = 214) ancestry. Compared to European Americans having any T allele of rs1042778, individuals homozygous for the alternate G allele reported significantly lower levels of negative affectivity and inhibited sociality, which in turn predicted significantly higher levels of social support and a larger/more diverse social network. Moreover, the effect of rs1042778 variation on social support was fully accounted for by associated differences in negative affectivity and inhibited sociality. Results replicated in the African American sample. Findings suggest that OXTR variation modulates levels of social support via proximal impacts on individual temperament. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Trends and variations of pH and hardness in a typical semi-arid river in a monsoon climate region during 1985-2009.

PubMed

Hao, Shaonan; Li, Xuyong; Jiang, Yan; Zhao, Hongtao; Yang, Lei

2016-09-01

The rapid growth of urbanization and industrialization, along with dramatic climate change, has strongly influenced hydrochemical characteristics in recent decades in China and thus could cause the variation of pH and general total hardness of a river. To explore such variations and their potential influencing factors in a river of the monsoon climate region, we analyzed a long-term monitoring dataset of pH, SO4 (2-), NOx, general total hardness (GH), Mg(2+), Ca(2+), and Cl(-) in surface water and groundwater in the Luan River basin from 1985 to 2009. The nonparametric Seasonal Kendall trend test was used to test the long-term trends of pH and GH. Relationship between the affecting factors, pH and GH were discussed. Results showed that pH showed a decreasing trend and that GH had an increasing trend in the long-term. Seasonal variation of pH and GH was mainly due to the typical monsoon climate. Results of correlation analysis showed that the unit area usage amounts of chemical fertilizer, NO3 (-), and SO4 (2-) were negatively correlated with pH in groundwater. In addition, mining activity affected GH spatial variation. Acid deposition, drought, and increasing the use of chemical fertilizers would contribute to the acidification trend, and mining activities would affect the spatial variation of GH. Variations of precipitation and runoff in semi-arid monsoon climate areas had significant influences on the pH and GH. Our findings implied that human activities played a critical role in river acidification in the semi-arid monsoon climate region of northern China.

Investigating the effects of climate variations on bacillary dysentery incidence in northeast China using ridge regression and hierarchical cluster analysis

PubMed Central

Huang, Desheng; Guan, Peng; Guo, Junqiao; Wang, Ping; Zhou, Baosen

2008-01-01

Background The effects of climate variations on bacillary dysentery incidence have gained more recent concern. However, the multi-collinearity among meteorological factors affects the accuracy of correlation with bacillary dysentery incidence. Methods As a remedy, a modified method to combine ridge regression and hierarchical cluster analysis was proposed for investigating the effects of climate variations on bacillary dysentery incidence in northeast China. Results All weather indicators, temperatures, precipitation, evaporation and relative humidity have shown positive correlation with the monthly incidence of bacillary dysentery, while air pressure had a negative correlation with the incidence. Ridge regression and hierarchical cluster analysis showed that during 1987–1996, relative humidity, temperatures and air pressure affected the transmission of the bacillary dysentery. During this period, all meteorological factors were divided into three categories. Relative humidity and precipitation belonged to one class, temperature indexes and evaporation belonged to another class, and air pressure was the third class. Conclusion Meteorological factors have affected the transmission of bacillary dysentery in northeast China. Bacillary dysentery prevention and control would benefit from by giving more consideration to local climate variations. PMID:18816415

Evolution in fluctuating environments: decomposing selection into additive components of the Robertson-Price equation.

PubMed

Engen, Steinar; Saether, Bernt-Erik

2014-03-01

We analyze the stochastic components of the Robertson-Price equation for the evolution of quantitative characters that enables decomposition of the selection differential into components due to demographic and environmental stochasticity. We show how these two types of stochasticity affect the evolution of multivariate quantitative characters by defining demographic and environmental variances as components of individual fitness. The exact covariance formula for selection is decomposed into three components, the deterministic mean value, as well as stochastic demographic and environmental components. We show that demographic and environmental stochasticity generate random genetic drift and fluctuating selection, respectively. This provides a common theoretical framework for linking ecological and evolutionary processes. Demographic stochasticity can cause random variation in selection differentials independent of fluctuating selection caused by environmental variation. We use this model of selection to illustrate that the effect on the expected selection differential of random variation in individual fitness is dependent on population size, and that the strength of fluctuating selection is affected by how environmental variation affects the covariance in Malthusian fitness between individuals with different phenotypes. Thus, our approach enables us to partition out the effects of fluctuating selection from the effects of selection due to random variation in individual fitness caused by demographic stochasticity. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Environmental variation at the onset of independent foraging affects full-grown body mass in the red fox

PubMed Central

Soulsbury, Carl D; Iossa, Graziella; Baker, Philip J; Harris, Stephen

2008-01-01

The period following the withdrawal of parental care has been highlighted as a key developmental period for juveniles. One reason for this is that juveniles cannot forage as competently as adults, potentially placing them at greater risk from environmentally-induced changes in food availability. However, no study has examined this topic. Using a long-term dataset on red foxes (Vulpes vulpes), we examined (i) dietary changes that occurred in the one-month period following the attainment of nutritional independence, (ii) diet composition in relation to climatic variation, and (iii) the effect of climatic variation on subsequent full-grown mass. Diet at nutritional independence contained increased quantities of easy-to-catch food items (earthworms and insects) when compared with pre-independence. Interannual variation in the volume of rainfall at nutritional independence was positively correlated to the proportion of earthworms in cub diet. Pre-independence cub mass and rainfall immediately following nutritional independence explained a significant proportion of variance in full-grown mass, with environmental variation affecting full-grown mass of the entire cohorts. Thus, weather-mediated availability of easy-to-catch food items at a key developmental stage has lifelong implications for the development of juvenile foxes by affecting full-grown mass, which in turn appears to be an important component of individual reproductive potential. PMID:18628118

Genetic differences between Chibcha and Non-Chibcha speaking tribes based on mitochondrial DNA (mtDNA) haplogroups from 21 Amerindian tribes from Colombia

PubMed Central

Usme-Romero, Solangy; Alonso, Milena; Hernandez-Cuervo, Helena; Yunis, Emilio J.; Yunis, Juan J.

2013-01-01

We analyzed the frequency of four mitochondrial DNA haplogroups in 424 individuals from 21 Colombian Amerindian tribes. Our results showed a high degree of mtDNA diversity and genetic heterogeneity. Frequencies of mtDNA haplogroups A and C were high in the majority of populations studied. The distribution of these four mtDNA haplogroups from Amerindian populations was different in the northern region of the country compared to those in the south. Haplogroup A was more frequently found among Amerindian tribes in northern Colombia, while haplogroup D was more frequent among tribes in the south. Haplogroups A, C and D have clinal tendencies in Colombia and South America in general. Populations belonging to the Chibcha linguistic family of Colombia and other countries nearby showed a strong genetic differentiation from the other populations tested, thus corroborating previous findings. Genetically, the Ingano, Paez and Guambiano populations are more closely related to other groups of south eastern Colombia, as also inferred from other genetic markers and from archeological data. Strong evidence for a correspondence between geographical and linguistic classification was found, and this is consistent with evidence that gene flow and the exchange of customs and knowledge and language elements between groups is facilitated by close proximity. PMID:23885195

[Clinal analysis of 202 nasal bone fractures cases].

PubMed

Zhong, Zhenhua; Fan, Xihui; Lian, Zhuang; Cheng, Zexing; Zhuang, Yuanling

2014-12-01

To evaluate the age, sex, etiology, diagnosis and treatment time of nasal bone fractures. Clinical data of 202 cases with nasal bone fractures treated in the hospital were retrospectively analysed. A total of 202 cases,163 men (80. 7%) and 39 women (19. 3%). Fifty-two patients had a relationship with alcohol consumption, and all of them were males. The most frequent reasons of the injury were fight 46. 5% (94 cases) followed by falling-down 21. 3% (43 cases), traffic accidents 19. 3% (39 cases), works related 6. 5% (13 cases), sport injuries 5. 9% (12 cases) and others 0. 5% (1 cases). Patients distribution in seasons were: spring 54 cases (26.7%), summer 42 cases (20.8%), autumn 58 cases (28.7%), winter 48 cases (23. 8%). Diagnosis of nasal bone fractures were made positively by x-ray films in 79. 7% of cases, but 100% by CT. Positive predictive value of CT was superior to that of X-ray films in the diagnosis of nasal bone fracture. High morbidity of nasal bone fracture was seen in the age group of 20-29 years, and predominantly in male. Fight was found to be the main etiologic factor. We think that CT is necessary for diagnosing nasal bone fracture.

Genetic differences between Chibcha and Non-Chibcha speaking tribes based on mitochondrial DNA (mtDNA) haplogroups from 21 Amerindian tribes from Colombia.

PubMed

Usme-Romero, Solangy; Alonso, Milena; Hernandez-Cuervo, Helena; Yunis, Emilio J; Yunis, Juan J

2013-07-01

We analyzed the frequency of four mitochondrial DNA haplogroups in 424 individuals from 21 Colombian Amerindian tribes. Our results showed a high degree of mtDNA diversity and genetic heterogeneity. Frequencies of mtDNA haplogroups A and C were high in the majority of populations studied. The distribution of these four mtDNA haplogroups from Amerindian populations was different in the northern region of the country compared to those in the south. Haplogroup A was more frequently found among Amerindian tribes in northern Colombia, while haplogroup D was more frequent among tribes in the south. Haplogroups A, C and D have clinal tendencies in Colombia and South America in general. Populations belonging to the Chibcha linguistic family of Colombia and other countries nearby showed a strong genetic differentiation from the other populations tested, thus corroborating previous findings. Genetically, the Ingano, Paez and Guambiano populations are more closely related to other groups of south eastern Colombia, as also inferred from other genetic markers and from archeological data. Strong evidence for a correspondence between geographical and linguistic classification was found, and this is consistent with evidence that gene flow and the exchange of customs and knowledge and language elements between groups is facilitated by close proximity.

Inference of chromosomal inversion dynamics from Pool-Seq data in natural and laboratory populations of Drosophila melanogaster.

PubMed

Kapun, Martin; van Schalkwyk, Hester; McAllister, Bryant; Flatt, Thomas; Schlötterer, Christian

2014-04-01

Sequencing of pools of individuals (Pool-Seq) represents a reliable and cost-effective approach for estimating genome-wide SNP and transposable element insertion frequencies. However, Pool-Seq does not provide direct information on haplotypes so that, for example, obtaining inversion frequencies has not been possible until now. Here, we have developed a new set of diagnostic marker SNPs for seven cosmopolitan inversions in Drosophila melanogaster that can be used to infer inversion frequencies from Pool-Seq data. We applied our novel marker set to Pool-Seq data from an experimental evolution study and from North American and Australian latitudinal clines. In the experimental evolution data, we find evidence that positive selection has driven the frequencies of In(3R)C and In(3R)Mo to increase over time. In the clinal data, we confirm the existence of frequency clines for In(2L)t, In(3L)P and In(3R)Payne in both North America and Australia and detect a previously unknown latitudinal cline for In(3R)Mo in North America. The inversion markers developed here provide a versatile and robust tool for characterizing inversion frequencies and their dynamics in Pool-Seq data from diverse D. melanogaster populations. © 2013 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Inference of chromosomal inversion dynamics from Pool-Seq data in natural and laboratory populations of Drosophila melanogaster

PubMed Central

Kapun, Martin; van Schalkwyk, Hester; McAllister, Bryant; Flatt, Thomas; Schlötterer, Christian

2014-01-01

Sequencing of pools of individuals (Pool-Seq) represents a reliable and cost-effective approach for estimating genome-wide SNP and transposable element insertion frequencies. However, Pool-Seq does not provide direct information on haplotypes so that, for example, obtaining inversion frequencies has not been possible until now. Here, we have developed a new set of diagnostic marker SNPs for seven cosmopolitan inversions in Drosophila melanogaster that can be used to infer inversion frequencies from Pool-Seq data. We applied our novel marker set to Pool-Seq data from an experimental evolution study and from North American and Australian latitudinal clines. In the experimental evolution data, we find evidence that positive selection has driven the frequencies of In(3R)C and In(3R)Mo to increase over time. In the clinal data, we confirm the existence of frequency clines for In(2L)t, In(3L)P and In(3R)Payne in both North America and Australia and detect a previously unknown latitudinal cline for In(3R)Mo in North America. The inversion markers developed here provide a versatile and robust tool for characterizing inversion frequencies and their dynamics in Pool-Seq data from diverse D. melanogaster populations. PMID:24372777

Paleoclimatic modeling and phylogeography of least killifish, Heterandria formosa: insights into Pleistocene expansion-contraction dynamics and evolutionary history of North American Coastal Plain freshwater biota.

PubMed

Bagley, Justin C; Sandel, Michael; Travis, Joseph; Lozano-Vilano, María de Lourdes; Johnson, Jerald B

2013-10-09

Climatic and sea-level fluctuations throughout the last Pleistocene glacial cycle (~130-0 ka) profoundly influenced present-day distributions and genetic diversity of Northern Hemisphere biotas by forcing range contractions in many species during the glacial advance and allowing expansion following glacial retreat ('expansion-contraction' model). Evidence for such range dynamics and refugia in the unglaciated Gulf-Atlantic Coastal Plain stems largely from terrestrial species, and aquatic species Pleistocene responses remain relatively uninvestigated. Heterandria formosa, a wide-ranging regional endemic, presents an ideal system to test the expansion-contraction model within this biota. By integrating ecological niche modeling and phylogeography, we infer the Pleistocene history of this livebearing fish (Poeciliidae) and test for several predicted distributional and genetic effects of the last glaciation. Paleoclimatic models predicted range contraction to a single southwest Florida peninsula refugium during the Last Glacial Maximum, followed by northward expansion. We inferred spatial-population subdivision into four groups that reflect genetic barriers outside this refuge. Several other features of the genetic data were consistent with predictions derived from an expansion-contraction model: limited intraspecific divergence (e.g. mean mtDNA p-distance = 0.66%); a pattern of mtDNA diversity (mean Hd = 0.934; mean π = 0.007) consistent with rapid, recent population expansion; a lack of mtDNA isolation-by-distance; and clinal variation in allozyme diversity with higher diversity at lower latitudes near the predicted refugium. Statistical tests of mismatch distributions and coalescent simulations of the gene tree lent greater support to a scenario of post-glacial expansion and diversification from a single refugium than to any other model examined (e.g. multiple-refugia scenarios). Congruent results from diverse data indicate H. formosa fits the classic Pleistocene expansion-contraction model, even as the genetic data suggest additional ecological influences on population structure. While evidence for Plio-Pleistocene Gulf Coast vicariance is well described for many freshwater species presently codistributed with H. formosa, this species demography and diversification departs notably from this pattern. Species-specific expansion-contraction dynamics may therefore have figured more prominently in shaping Coastal Plain evolutionary history than previously thought. Our findings bolster growing appreciation for the complexity of phylogeographical structuring within North America's southern refugia, including responses of Coastal Plain freshwater biota to Pleistocene climatic fluctuations.

Deciphering molecular circuits from genetic variation underlying transcriptional responsiveness to stimuli

PubMed Central

Gat-Viks, Irit; Chevrier, Nicolas; Wilentzik, Roni; Eisenhaure, Thomas; Raychowdhury, Raktima; Steuerman, Yael; Shalek, Alex; Hacohen, Nir; Amit, Ido; Regev, Aviv

2013-01-01

Individual genetic variation affects gene expression in response to stimuli, often by influencing complex molecular circuits. Here we combine genomic and intermediate-scale transcriptional profiling with computational methods to identify variants that affect the responsiveness of genes to stimuli (responsiveness QTLs; reQTLs) and to position these variants in molecular circuit diagrams. We apply this approach to study variation in transcriptional responsiveness to pathogen components in dendritic cells from recombinant inbred mouse strains. We identify reQTLs that correlate with particular stimuli and position them in known pathways. For example, in response to a virus-like stimulus, a trans-acting variant acts as an activator of the antiviral response; using RNAi, we identify Rgs16 as the likely causal gene. Our approach charts an experimental and analytic path to decipher the mechanisms underlying genetic variation in circuits that control responses to stimuli. PMID:23503680

Deciphering molecular circuits from genetic variation underlying transcriptional responsiveness to stimuli.

PubMed

Gat-Viks, Irit; Chevrier, Nicolas; Wilentzik, Roni; Eisenhaure, Thomas; Raychowdhury, Raktima; Steuerman, Yael; Shalek, Alex K; Hacohen, Nir; Amit, Ido; Regev, Aviv

2013-04-01

Individual genetic variation affects gene responsiveness to stimuli, often by influencing complex molecular circuits. Here we combine genomic and intermediate-scale transcriptional profiling with computational methods to identify variants that affect the responsiveness of genes to stimuli (responsiveness quantitative trait loci or reQTLs) and to position these variants in molecular circuit diagrams. We apply this approach to study variation in transcriptional responsiveness to pathogen components in dendritic cells from recombinant inbred mouse strains. We identify reQTLs that correlate with particular stimuli and position them in known pathways. For example, in response to a virus-like stimulus, a trans-acting variant responds as an activator of the antiviral response; using RNA interference, we identify Rgs16 as the likely causal gene. Our approach charts an experimental and analytic path to decipher the mechanisms underlying genetic variation in circuits that control responses to stimuli.

Diel cycles in dissolved barium, lead, iron, vanadium, and nitrite in a stream draining a former zinc smelter site near Hegeler, Illinois

USGS Publications Warehouse

Kay, R.T.; Groschen, G.E.; Cygan, G.; Dupre, David H.

2011-01-01

Diel variations in the concentrations of a number of constituents have the potential to substantially affect the appropriate sampling regimen in acidic streams. Samples taken once during the course of the day cannot adequately reflect diel variations in water quality and may result in an inaccurate understanding of biogeochemical processes, ecological conditions, and of the threat posed by the water to human health and the associated wildlife. Surface water and groundwater affected by acid drainage were sampled every 60 to 90. min over a 48-hour period at a former zinc smelter known as the Hegeler Zinc Superfund Site, near Hegeler, Illinois. Diel variations related to water quality in the aquifer were not observed in groundwater. Diel variations were observed in the temperature, pH, and concentration of dissolved oxygen, nitrite, barium, iron, lead, vanadium, and possibly uranium in surface water. Temperature, dissolved oxygen, nitrite, barium, lead, and uranium generally attained maximum values during the afternoon and minimum values during the night. Iron, vanadium, and pH generally attained minimum values during the afternoon and maximum values during the night. Concentrations of dissolved oxygen were affected by the intensity of photosynthetic activity and respiration, which are dependent upon insolation. Nitrite, an intermediary in many nitrogen reactions, may have been formed by the oxidation of ammonium by dissolved oxygen and converted to other nitrogen species as part of the decomposition of organic matter. The timing of the pH cycles was distinctly different from the cycles found in Midwestern alkaline streams and likely was the result of the photoreduction of Fe3+ to Fe 2+ and variations in the intensity of precipitation of hydrous ferric oxide minerals. Diel cycles of iron and vanadium also were primarily the result of variations in the intensity of precipitation of hydrous ferric oxide minerals. The diel variation in the concentrations of lead, uranium, and barium may have been affected by competition with Fe+2 for sorption sites on hydrous ferric oxide minerals. ?? 2010.

ANALYSIS ON THE VARIATION OF MEDIAL ROTATION VALUES ACCORDING TO THE POSITION OF THE HUMERAL DIAPHYSIS.

PubMed

Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; da Silva, Luciana Andrade; do Val Sella, Guilherme; Cohen, Carina; Busin Giora, Taís Stedile; Checchia, Sergio Luiz; Raia, Fabio; Pekelman, Hélio; Cymrot, Raquel

2012-01-01

To analyze the validity of measurements of medial rotation (MR) of the shoulder, using vertebral levels, according to the variation in the position of the humeral diaphysis, and to test the bi-goniometer as a new measuring instrument. 140 shoulders (70 patients) were prospectively evaluated in cases presenting unilateral shoulder MR limitation. The vertebral level was evaluated by means of a visual scale and was correlated with the angle obtained according to the position of the humeral diaphysis, using the bi-goniometer developed with the Department of Mechanical Engineering of Mackenzie University. The maximum vertebral level reached through MR on the unaffected side ranged from T3 to T12, and on the affected side, from T6 to the trochanter. Repositioning of the affected limb in MR according to the angular values on the normal side showed that 57.13% of the patients reached lower levels, between the sacrum, gluteus and trochanter. From analysis on the maximum vertebral level attained and the variation between the affected angle x (frontal plane: abduction and MR of the shoulder) and the unaffected angle x in MR, we observed that the greater the angle of the diaphyseal axis was, the lower the variation in the vertebral level attained was. From evaluating the linear correlation between the variables of difference in maximum vertebral level reached and variation in the affected angle y (extension and abduction of the shoulder) and the unaffected angle y in MR, we observed that there was no well-established linear relationship between these variables. Measurement of MR using vertebral levels does not correspond to the real values, since it varies according to the positioning of the humeral diaphysis.

ANALYSIS ON THE VARIATION OF MEDIAL ROTATION VALUES ACCORDING TO THE POSITION OF THE HUMERAL DIAPHYSIS

PubMed Central

Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; da Silva, Luciana Andrade; do Val Sella, Guilherme; Cohen, Carina; Busin Giora, Taís Stedile; Checchia, Sergio Luiz; Raia, Fabio; Pekelman, Hélio; Cymrot, Raquel

2015-01-01

Objective: To analyze the validity of measurements of medial rotation (MR) of the shoulder, using vertebral levels, according to the variation in the position of the humeral diaphysis, and to test the bi-goniometer as a new measuring instrument. Methods: 140 shoulders (70 patients) were prospectively evaluated in cases presenting unilateral shoulder MR limitation. The vertebral level was evaluated by means of a visual scale and was correlated with the angle obtained according to the position of the humeral diaphysis, using the bi-goniometer developed with the Department of Mechanical Engineering of Mackenzie University. Results: The maximum vertebral level reached through MR on the unaffected side ranged from T3 to T12, and on the affected side, from T6 to the trochanter. Repositioning of the affected limb in MR according to the angular values on the normal side showed that 57.13% of the patients reached lower levels, between the sacrum, gluteus and trochanter. From analysis on the maximum vertebral level attained and the variation between the affected angle x (frontal plane: abduction and MR of the shoulder) and the unaffected angle x in MR, we observed that the greater the angle of the diaphyseal axis was, the lower the variation in the vertebral level attained was. From evaluating the linear correlation between the variables of difference in maximum vertebral level reached and variation in the affected angle y (extension and abduction of the shoulder) and the unaffected angle y in MR, we observed that there was no well-established linear relationship between these variables. Conclusion: Measurement of MR using vertebral levels does not correspond to the real values, since it varies according to the positioning of the humeral diaphysis. PMID:27047845

Using active shape modeling based on MRI to study morphologic and pitch-related functional changes affecting vocal structures and the airway.

PubMed

Miller, Nicola A; Gregory, Jennifer S; Aspden, Richard M; Stollery, Peter J; Gilbert, Fiona J

2014-09-01

The shape of the vocal tract and associated structures (eg, tongue and velum) is complicated and varies according to development and function. This variability challenges interpretation of voice experiments. Quantifying differences between shapes and understanding how vocal structures move in relation to each other is difficult using traditional linear and angle measurements. With statistical shape models, shape can be characterized in terms of independent modes of variation. Here, we build an active shape model (ASM) to assess morphologic and pitch-related functional changes affecting vocal structures and the airway. Using a cross-sectional study design, we obtained six midsagittal magnetic resonance images from 10 healthy adults (five men and five women) at rest, while breathing out, and while listening to, and humming low and high notes. Eighty landmark points were chosen to define the shape of interest and an ASM was built using these (60) images. Principal component analysis was used to identify independent modes of variation, and statistical analysis was performed using one-way repeated-measures analysis of variance. Twenty modes of variation were identified with modes 1 and 2 accounting for half the total variance. Modes 1 and 9 were significantly associated with humming low and high notes (P < 0.001) and showed coordinated changes affecting the cervical spine, vocal structures, and airway. Mode 2 highlighted wide structural variations between subjects. This study highlights the potential of active shape modeling to advance understanding of factors underlying morphologic and pitch-related functional variations affecting vocal structures and the airway in health and disease. Copyright © 2014 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Seed size variation in the palm Euterpe edulis and the effects of seed predators on germination and seedling survival

NASA Astrophysics Data System (ADS)

Pizo, Marco A.; Von Allmen, Christiane; Morellato, L. Patricia C.

2006-05-01

Intraspecific variation in seed size is common in wild plant populations and has important consequences for the reproductive success of individual plants. Multiple, often conflicting evolutionary forces mediated by biotic as well as abiotic agents may maintain such a variation. In this paper we assessed seed size variation in a population of the threatened, commercially important palm Euterpe edulis in southeast Brazil. We investigated (i) how this variation affects the probability of attack by vertebrate and invertebrate post-dispersal seed predators, and (ii) if seed size influences the outcome of seeds damaged by beetles in terms of seed germination and early survival of seedlings. Euterpe edulis seeds varied in diameter from 8.3 to 14.1 mm. Neither insects nor rodents selected the seeds they preyed upon based on seed size. Seed germination and total, shoot and root biomasses of one-year seedlings were significantly and positively affected by seed size. Root biomass and seedling survival were negatively affected by seed damage caused by a scolytid beetle ( Coccotrypes palmarum) whose adults bore into seeds to consume part of the endosperm, but do not oviposit on them. Seed size had a marginally significant effect on seedling survival. Therefore, if any advantage is accrued by E. edulis individuals producing large seeds, this is because of greater seed germination success and seedling vigor. If this is so, even a relatively narrow range of variation in seed size as observed in the E. edulis population studied may translate into differential success of individual plants.

Diurnal lighting patterns and habitat alter opsin expression and colour preferences in a killifish

PubMed Central

Johnson, Ashley M.; Stanis, Shannon; Fuller, Rebecca C.

2013-01-01

Spatial variation in lighting environments frequently leads to population variation in colour patterns, colour preferences and visual systems. Yet lighting conditions also vary diurnally, and many aspects of visual systems and behaviour vary over this time scale. Here, we use the bluefin killifish (Lucania goodei) to compare how diurnal variation and habitat variation (clear versus tannin-stained water) affect opsin expression and the preference to peck at different-coloured objects. Opsin expression was generally lowest at midnight and dawn, and highest at midday and dusk, and this diurnal variation was many times greater than variation between habitats. Pecking preference was affected by both diurnal and habitat variation but did not correlate with opsin expression. Rather, pecking preference matched lighting conditions, with higher preferences for blue at noon and for red at dawn/dusk, when these wavelengths are comparatively scarce. Similarly, blue pecking preference was higher in tannin-stained water where blue wavelengths are reduced. In conclusion, L. goodei exhibits strong diurnal cycles of opsin expression, but these are not tightly correlated with light intensity or colour. Temporally variable pecking preferences probably result from lighting environment rather than from opsin production. These results may have implications for the colour pattern diversity observed in these fish. PMID:23698009

Seasonal Variations of Atmospheric CO2 over Fire Affected Regions Based on GOSAT Observations

NASA Astrophysics Data System (ADS)

Shi, Y.; Matsunaga, T.

2016-12-01

Abstract: The carbon dioxide (CO2) emissions released from biomass burning significantly affect the temporal variations of atmospheric CO2 concentrations. Based on a long-term (July 2009-June 2015) retrieved datasets by the Greenhouse Gases Observing Satellite (GOSAT), the seasonal cycle and interannual variations of column-averaged volume mixing ratios of atmospheric carbon dioxide (XCO2) in four fire affected continental regions were investigated. The results showed Northern Africa had the largest seasonal variations after removing its regional long-term trend of XCO2 with peak-to-peak amplitude of 6.2 ppm within the year, higher than central South America (2.4 ppm), Southern Africa (3.8 ppm) and Australia (1.7 ppm). The detrended regional XCO2 was found to be positively correlated with the fire CO2 emissions during fire activity period and negatively correlated with vegetation photosynthesis activity with different seasonal variabilities. Northern Africa recorded the largest change of seasonal variations of detrended XCO2 with a total of 12.8 ppm during fire seasons, higher than central South America, Southern Africa and Australia with 5.4 ppm, 6.7 ppm and 2.2 ppm, respectively. During fire episode, the positive detrended XCO2 was noticed during June-November in central South America, December-June in Northern Africa, May-November in Southern Africa. The Pearson correlation coefficients between the variations of detrended XCO2 and fire CO2 emissions from GFED4 (Global Fire Emissions Database v4) achieved best correlations in Southern Africa (R=0.77, p<0.05). Meanwhile, Southern Africa also experienced a significant negative relationship between the variations of detrended XCO2 and vegetation activity (R=-0.84, p<0.05). This study revealed that fire CO2 emissions and vegetation activity contributed greatly to the seasonal variations of GOSAT XCO2 dataset.

Extended monitoring and analysis of moisture-temperature data

DOT National Transportation Integrated Search

2001-10-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, nine moisture-temperature-...

Intra-individual and inter-individual variations in sperm aneuploidy frequencies in normal men.

PubMed

Tempest, Helen G; Ko, Evelyn; Rademaker, Alfred; Chan, Peter; Robaire, Bernard; Martin, Renée H

2009-01-01

To investigate whether there are intra-individual and/or inter-individual variations in sperm aneuploidy frequencies within the normal male population, and, if this is the case, whether they are sporadic or time-stable variants. Prospective study. University research laboratory. Ten men aged 18-32 years. None. Fluorescence in situ hybridization was used to investigate sperm aneuploidy frequencies for chromosomes X, Y, 13, and 21 in serial semen samples collected over a period of 12-18 months. Intra-individual and inter-individual variations were investigated by comparing serial samples from the same donor and by comparing the donors with each other, respectively. Intra-individual variations were found in all 10 donors for at least one investigated chromosome; variations tended to be sporadic events affecting only one time point. Inter-individual variations were found for all chromosomes (except XX and YY disomy and disomy 21), with three men identified as stable variants, consistently producing higher levels of aneuploidy for at least one of the following aneuploidies: sex chromosome nullisomy; disomy 13, or diploidy. These results suggest that there are a number of factors and mechanisms that have the potential to sporadically or consistently affect sperm aneuploidy.

Assessing Self-concept as a Mediator Between Anger and Resilience in Adolescents With Cancer in Taiwan.

PubMed

Wu, Wei-Wen; Chang, Joanne T; Tsai, Shao-Yu; Liang, Shu-Yuan

Anger is considered a common method used by patients to relieve emotional frustrations. However, this emotional response is not a common research focus for adolescents with cancer. The aim of this study was to determine whether self-concept mediated the relationship between anger and resilience for adolescent patients currently being treated for cancer. A cross-sectional study of 40 adolescents with cancer was conducted. The instruments included the Chinese Beck Self-Concept Inventory, the Chinese Beck Anger Inventory, and the Chinese Resilience Scale. Mediation analysis was also conducted. The results indicate that (1) variations in anger significantly account for 6.86% of observed variations in self-concept, (2) variations in self-concept significantly account for 52.83% of observed variations in resilience, (3) variations in anger significantly account for 10.96% of observed variations in resilience, and (4) when paths in conditions 1 and 2 were controlled, variations in anger through self-concept significantly account for 54.04% of observed variations in resilience, and variations in anger did not significantly account for observed variations in resilience. Gender and age might affect anger control. Despite worse physical functioning and an impacted appearance, participants had normative-to-positive self-concept levels, suggesting that their self-concept might not be affected by cancer. Self-concept might play a mediating role between anger and resilience, thus helping to bridge this knowledge gap. The current gap in knowledge regarding the mediating relationship necessitates the implementation of a large-scale study designed to verify the mediating role of self-concept between anger and resilience.

Temporal variations in sirtuin expression under normal and ultraviolet B-induced conditions and their correlation to energy levels in normal human epidermal keratinocytes.

PubMed

Pelle, Edward; Dong, Kelly; Pernodet, Nadine

2015-01-01

Sirtuins are post-translational modifiers that affect transcriptional signaling, metabolism, and DNA repair. Although originally identified as gene silencers capable of extending cell lifespan, the involvement of sirtuins in many different areas of cell biology has now become widespread. Our approach has been to study the temporal variation and also the effect of environmental stressors, such as ultraviolet B (UVB) and ozone, on sirtuin expression in human epidermal keratinocytes. In this report, we measured the variation in expression of several sirtuins over time and also show how a low dose of UVB can affect this pattern of expression. Moreover, we correlated these changes to variations in hydrogen peroxide (H2O2) and ATP levels. Our data show significant variations in normal sirtuin expression, which may indicate a generalized response by sirtuins to cell cycle kinetics. These results also demonstrate that sirtuins as a family of molecules are sensitive to UVB-induced disruption and may suggest a new paradigm for determining environmental stress on aging and provide direction for the development of new cosmetic products.

Extended monitoring and analysis of moisture temperature data : [executive summary].

DOT National Transportation Integrated Search

2001-01-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, nine moisture-temperature-...

Serotonin and Early Cognitive Development: Variation in the Tryptophan Hydroxylase 2 Gene Is Associated with Visual Attention in 7-Month-Old Infants

ERIC Educational Resources Information Center

Leppanen, Jukka M.; Peltola, Mikko J.; Puura, Kaija; Mantymaa, Mirjami; Mononen, Nina; Lehtimaki, Terho

2011-01-01

Background: Allelic variation in the promoter region of a gene that encodes tryptophan hydroxylase isoform 2 (TPH2), a rate-limiting enzyme of serotonin synthesis in the central nervous system, has been associated with variations in cognitive function and vulnerability to affective spectrum disorders. Little is known about the effects of this gene…

Form of an evolutionary tradeoff affects eco-evolutionary dynamics in a predator-prey system.

PubMed

Kasada, Minoru; Yamamichi, Masato; Yoshida, Takehito

2014-11-11

Evolution on a time scale similar to ecological dynamics has been increasingly recognized for the last three decades. Selection mediated by ecological interactions can change heritable phenotypic variation (i.e., evolution), and evolution of traits, in turn, can affect ecological interactions. Hence, ecological and evolutionary dynamics can be tightly linked and important to predict future dynamics, but our understanding of eco-evolutionary dynamics is still in its infancy and there is a significant gap between theoretical predictions and empirical tests. Empirical studies have demonstrated that the presence of genetic variation can dramatically change ecological dynamics, whereas theoretical studies predict that eco-evolutionary dynamics depend on the details of the genetic variation, such as the form of a tradeoff among genotypes, which can be more important than the presence or absence of the genetic variation. Using a predator-prey (rotifer-algal) experimental system in laboratory microcosms, we studied how different forms of a tradeoff between prey defense and growth affect eco-evolutionary dynamics. Our experimental results show for the first time to our knowledge that different forms of the tradeoff produce remarkably divergent eco-evolutionary dynamics, including near fixation, near extinction, and coexistence of algal genotypes, with quantitatively different population dynamics. A mathematical model, parameterized from completely independent experiments, explains the observed dynamics. The results suggest that knowing the details of heritable trait variation and covariation within a population is essential for understanding how evolution and ecology will interact and what form of eco-evolutionary dynamics will result.

Climate variation alters the synchrony of host–parasitoid interactions

USDA-ARS?s Scientific Manuscript database

Although some research has examined how parasitoids will respond to colder temperatures or experimental warming, we know relatively little about how increased variation in temperature could affect interactions between parasitoids and their hosts. Using a study system consisting of emerald ash borer...

Ethnic Variation in Classroom Interaction: Myth or Reality.

ERIC Educational Resources Information Center

Kumaravadivelu, B.

1990-01-01

A study of ethnic variation supports the hypothesis that rules/norms governing second-language classroom interactional patterns are affected by the teacher's pedagogical orientation and turn allocation management, learner disposition/motivation toward participation, and interactional opportunities. It cautions against hasty linkages between…

Individual variation affects departure rate from the natal pond in an ephemeral pond-breeding anuran

USGS Publications Warehouse

Chelgren, N.D.; Rosenberg, D.K.; Heppell, S.S.; Gitelman, A.I.

2008-01-01

Frogs exhibit extreme plasticity and individual variation in growth and behavior during metamorphosis, driven by interactions of intrinsic state factors and extrinsic environmental factors. In northern red-legged frogs (Rana aurora Baird and Girard, 1852), we studied the timing of departure from the natal pond as it relates to date and size of individuals at metamorphosis in the context of environmental uncertainty. To affect body size at metamorphosis, we manipulated food availability during the larval stage for a sample (317) of 1045 uniquely marked individuals and released them at their natal ponds as newly metamorphosed frogs. We recaptured 34% of marked frogs in pitfall traps as they departed and related the timing of their initial terrestrial movements to individual properties using a time-to-event model. Median age at first capture was 4 and 9 days postmetamorphosis at two sites. The rate of departure was positively related to body size and to date of metamorphosis. Departure rate was strongly negatively related to time elapsed since rainfall, and this effect was diminished for smaller and later metamorphosing frogs. Individual variation in metamorphic traits thus affects individuals' responses to environmental variability, supporting a behavioral link with variation in survival associated with these same metamorphic traits. ?? 2008 NRC.

Individual variation in behavioural plasticity: direct and indirect effects of boldness, exploration and sociability on habituation to predators in lizards.

PubMed

Rodríguez-Prieto, Iñaki; Martín, José; Fernández-Juricic, Esteban

2011-01-22

Little is known about the factors causing variation in behavioural plasticity and the interplay between personality and plasticity. Habituation to predators is a special case of behavioural plasticity. We investigated the direct and indirect effects of boldness, exploration and sociability traits on the habituation ability of Iberian wall lizards, considering exposure and sex effects. Individual boldness was consistent across several non-habituation contexts, but it did not significantly affect habituation. Exploration had a strong direct effect on habituation, with more exploratory individuals being able to habituate faster than less exploratory ones, probably because of their ability to assess risk better. Individual variation in habituation was also affected by sociability, but this was an indirect effect mediated by exposure to the predator. Less social individuals avoided refuges with conspecific cues, increasing exposure to the predator and eventually habituation. Finally, the direct effects of sex (females habituated faster than males) were opposite to its indirect effects through exposure. We conclude that risk assessment, instead of the proactivity-reactivity gradient usually considered in the literature, can affect behavioural plasticity through complex interactions between direct and indirect effects, including exploratory behaviour, degree of exposure to the predator and sex, which represent novel mechanisms generating inter-individual variation in plasticity.

Evaluation of sources of variation on in vitro fermentation kinetics of feedstuffs in a gas production system.

PubMed

Keim, Juan P; Alvarado-Gilis, Christian; Arias, Rodrigo A; Gandarillas, Mónica; Cabanilla, Jaime

2017-10-01

The aim of this study was to evaluate the effect of different sources of variation in gas production technique on the in vitro gas production kinetics of feedstuffs. Triplicates of commercial concentrate, grass silage, grass hay and grass pasture were incubated in three experiments: experiment 1 assessed two agitation methods; experiment 2 evaluated different rumen inocula (pooled or different donor cows for each incubation run); and experiment 3 used Goering-Van Soest or Mould buffers for media preparation. Gas production data were fitted into the Michaelis-Menten model and then subjected to analysis of variance. Gas production (GP) at 48 h and asymptote gas production (A) were lower when bottles were continuously under horizontal movement. Time to produce half and 75% of A, and A were affected by rumen inocula, while buffer type affected time to produce half and 25% of A and GP. No interactions between substrates and sources of variation were observed, suggesting that the effects of substrates on GP parameters were not modified. It is concluded that comparison of numerical data from in vitro experiments that follow different protocols must be done carefully. However, the ranking of different substrates is more robust and less affected by the sources of variation. © 2017 Japanese Society of Animal Science.

How does variation in the environment and individual cognition explain the existence of consistent behavioral differences?

PubMed Central

Niemelä, Petri T; Vainikka, Anssi; Forsman, Jukka T; Loukola, Olli J; Kortet, Raine

2013-01-01

According to recent studies on animal personalities, the level of behavioral plasticity, which can be viewed as the slope of the behavioral reaction norm, varies among individuals, populations, and species. Still, it is conceptually unclear how the interaction between environmental variation and variation in animal cognition affect the evolution of behavioral plasticity and expression of animal personalities. Here, we (1) use literature to review how environmental variation and individual variation in cognition explain population and individual level expression of behavioral plasticity and (2) draw together empirically yet nontested, conceptual framework to clarify how these factors affect the evolution and expression of individually consistent behavior in nature. The framework is based on simple principles: first, information acquisition requires cognition that is inherently costly to build and maintain. Second, individual differences in animal cognition affect the differences in behavioral flexibility, i.e. the variance around the mean of the behavioral reaction norm, which defines plasticity. Third, along the lines of the evolution of cognition, we predict that environments with moderate variation favor behavioral flexibility. This occurs since in those environments costs of cognition are covered by being able to recognize and use information effectively. Similarly, nonflexible, stereotypic behaviors may be favored in environments that are either invariable or highly variable, since in those environments cognition does not give any benefits to cover the costs or cognition is not able to keep up with environmental change, respectively. If behavioral plasticity develops in response to increasing environmental variability, plasticity should dominate in environments that are moderately variable, and expression of animal personalities and behavioral syndromes may differ between environments. We give suggestions how to test our hypothesis and propose improvements to current behavioral testing protocols in the field of animal personality. PMID:23467316

Environmental Variation Generates Environmental Opportunist Pathogen Outbreaks.

PubMed

Anttila, Jani; Kaitala, Veijo; Laakso, Jouni; Ruokolainen, Lasse

2015-01-01

Many socio-economically important pathogens persist and grow in the outside host environment and opportunistically invade host individuals. The environmental growth and opportunistic nature of these pathogens has received only little attention in epidemiology. Environmental reservoirs are, however, an important source of novel diseases. Thus, attempts to control these diseases require different approaches than in traditional epidemiology focusing on obligatory parasites. Conditions in the outside-host environment are prone to fluctuate over time. This variation is a potentially important driver of epidemiological dynamics and affect the evolution of novel diseases. Using a modelling approach combining the traditional SIRS models to environmental opportunist pathogens and environmental variability, we show that epidemiological dynamics of opportunist diseases are profoundly driven by the quality of environmental variability, such as the long-term predictability and magnitude of fluctuations. When comparing periodic and stochastic environmental factors, for a given variance, stochastic variation is more likely to cause outbreaks than periodic variation. This is due to the extreme values being further away from the mean. Moreover, the effects of variability depend on the underlying biology of the epidemiological system, and which part of the system is being affected. Variation in host susceptibility leads to more severe pathogen outbreaks than variation in pathogen growth rate in the environment. Positive correlation in variation on both targets can cancel the effect of variation altogether. Moreover, the severity of outbreaks is significantly reduced by increase in the duration of immunity. Uncovering these issues helps in understanding and controlling diseases caused by environmental pathogens.

The capture of heritable variation for genetic quality through social competition.

PubMed

Wolf, Jason B; Harris, W Edwin; Royle, Nick J

2008-09-01

In theory, females of many species choose mates based on traits that are indicators of male genetic quality. A fundamental question in evolutionary biology is why genetic variation for such indicator traits persists despite strong persistent selection imposed by female preference, which is known as the lek paradox. One potential solution to the lek paradox suggests that the traits that are targets of mate choice should evolve condition-dependent expression and that condition should have a large genetic variance. Condition is expected to exhibit high genetic variance because it is affected by a large number of physiological processes and hence, condition-dependent traits should 'capture' variation contributed by a large number of loci. We suggest that a potentially important cause of variation in condition is competition for limited resources. Here, we discuss a pair of models to analyze the evolutionary genetics of traits affected by success in social competition for resources. We show that competition can contribute to genetic variation of 'competition-dependent' traits that have fundamentally different evolutionary properties than other sources of variation. Competition dependence can make traits honest indicators of genetic quality by revealing the relative competitive ability of males, can provide a component of heritable variation that does not contribute to trait evolution, and can help maintain heritable variation under directional selection. Here we provide a general introduction to the concept of competition dependence and briefly introduce two models to demonstrate the potential evolutionary consequences of competition-dependent trait expression.

Identification of structural variation in mouse genomes.

PubMed

Keane, Thomas M; Wong, Kim; Adams, David J; Flint, Jonathan; Reymond, Alexandre; Yalcin, Binnaz

2014-01-01

Structural variation is variation in structure of DNA regions affecting DNA sequence length and/or orientation. It generally includes deletions, insertions, copy-number gains, inversions, and transposable elements. Traditionally, the identification of structural variation in genomes has been challenging. However, with the recent advances in high-throughput DNA sequencing and paired-end mapping (PEM) methods, the ability to identify structural variation and their respective association to human diseases has improved considerably. In this review, we describe our current knowledge of structural variation in the mouse, one of the prime model systems for studying human diseases and mammalian biology. We further present the evolutionary implications of structural variation on transposable elements. We conclude with future directions on the study of structural variation in mouse genomes that will increase our understanding of molecular architecture and functional consequences of structural variation.

Polarization variations in installed fibers and their influence on quantum key distribution systems.

PubMed

Ding, Yu-Yang; Chen, Hua; Wang, Shuang; He, De-Yong; Yin, Zhen-Qiang; Chen, Wei; Zhou, Zheng; Guo, Guang-Can; Han, Zheng-Fu

2017-10-30

Polarization variations in the installed fibers are complex and volatile, and would severely affect the performances of polarization-sensitive quantum key distribution (QKD) systems. Based on the recorded data about polarization variations of different installed fibers, we establish an analytical methodology to quantitatively evaluate the influence of polarization variations on polarization-sensitive QKD systems. Using the increased quantum bit error rate induced by polarization variations as a key criteria, we propose two parameters - polarization drift time and required tracking speed - to characterize polarization variations. For field buried and aerial fibers with different length, we quantitatively evaluate the influence of polarization variations, and also provide requirements and suggestions for polarization basis alignment modules of QKD systems deployed in different kind of fibers.

Spatial-temporal variation of parasites in Cnemidophorus ocellifer (Teiidae) and Tropidurus hispidus and Tropidurus semitaeniatus (Tropiduridae) from Caatinga areas in northeastern Brazil.

PubMed

Brito, Samuel V; Ferreira, Felipe S; Ribeiro, Samuel C; Anjos, Luciano A; Almeida, Waltécio O; Mesquita, Daniel O; Vasconcellos, Alexandre

2014-03-01

Parasites are natural regulators of their host populations. Despite this, little is known about variations in parasite composition (spatially or temporally) in environments subjected to water-related periodic stress such as the arid and semiarid regions. The objective of this study was to evaluate the spatial-temporal variation in endoparasite species' abundance and richness in populations of Neotropical Cnemidophorus ocellifer, Tropidurus hispidus, and Tropidurus semitaeniatus lizards in the semiarid northeast of Brazil. The location influenced the abundance of parasites in all analyzed lizard species, while season (dry and rainy) only influenced the total abundance for T. hispidus. In all seasons, males significantly showed more endoparasites than females in all lizard species, although for T. hispidus, this difference was only found in the dry season. Seasonal variations affect the abundance patterns of parasites. Likely, variables include environmental variations such as humidity and temperature, which influence the development of endoparasite eggs when outside of the host. Further, the activity of the intermediate hosts and the parasites of heteroxenous life cycles could be affected by an environmental condition. The variation in the abundance of parasites between the sampling areas could be a reflection of variations in climate and physiochemical conditions. Also, it could be due to differences in the quality of the environment in which each host population lives.

Additive genetic variation and evolvability of a multivariate trait can be increased by epistatic gene action.

PubMed

Griswold, Cortland K

2015-12-21

Epistatic gene action occurs when mutations or alleles interact to produce a phenotype. Theoretically and empirically it is of interest to know whether gene interactions can facilitate the evolution of diversity. In this paper, we explore how epistatic gene action affects the additive genetic component or heritable component of multivariate trait variation, as well as how epistatic gene action affects the evolvability of multivariate traits. The analysis involves a sexually reproducing and recombining population. Our results indicate that under stabilizing selection conditions a population with a mixed additive and epistatic genetic architecture can have greater multivariate additive genetic variation and evolvability than a population with a purely additive genetic architecture. That greater multivariate additive genetic variation can occur with epistasis is in contrast to previous theory that indicated univariate additive genetic variation is decreased with epistasis under stabilizing selection conditions. In a multivariate setting, epistasis leads to less relative covariance among individuals in their genotypic, as well as their breeding values, which facilitates the maintenance of additive genetic variation and increases a population׳s evolvability. Our analysis involves linking the combinatorial nature of epistatic genetic effects to the ancestral graph structure of a population to provide insight into the consequences of epistasis on multivariate trait variation and evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

The response of fabric variations to simple shear and migration recrystallization

DOE PAGES

Kennedy, Joseph H.; Pettit, Erin C.

2015-06-01

The observable microstructures in ice are the result of many dynamic and competing processes. These processes are influenced by climate variables in the firn. Layers deposited in different climate regimes may show variations in fabric which can persist deep into the ice sheet; fabric may 'remember' these past climate regimes. In this paper, we model the evolution of fabric variations below the firn–ice transition and show that the addition of shear to compressive-stress regimes preserves the modeled fabric variations longer than compression-only regimes, because shear drives a positive feedback between crystal rotation and deformation. Even without shear, the modeled icemore » retains memory of the fabric variation for ~200 ka in typical polar ice-sheet conditions. Our model shows that temperature affects how long the fabric variation is preserved, but only affects the strain-integrated fabric evolution profile when comparing results straddling the thermal-activation-energy threshold (~–10°C). Even at high temperatures, migration recrystallization does not eliminate the modeled fabric's memory under most conditions. High levels of nearest-neighbor interactions will, however, eliminate the modeled fabric's memory more quickly than low levels of nearest-neighbor interactions. Finally, our model predicts that fabrics will retain memory of past climatic variations when subject to a wide variety of conditions found in polar ice sheets.« less

Seasonal and diurnal variations of ocular pressure in ocular hypertensive subjects in Pakistan.

PubMed

Qureshi, I A; Xiao, R X; Yang, B H; Zhang, J; Xiang, D W; Hui, J L

1999-05-01

Studies have been shown that intraocular pressure (IOP) shows a diurnal variation in ocular hypertensive subjects, but the amount of change differs from study to study. In recent years it has been noted that intraocular pressure is a dynamic function and is subjected to many influences both acutely and over the long term. The variability in the results may be due to negligence of factors that can affect IOP. Moreover, seasonal variations in the ocular hypertensive subjects have never been described. After placing control on those factors that can affect IOP, this study investigated seasonal and diurnal variations in IOP of ocular hypertensive subjects. IOP was measured each month over the course of 12 months with the Goldmann applanation tonometer in 91 ocular hypertensive male subjects. To see the diurnal changes, subjects were asked to stay in the hospital for 24 hours. The average IOP in the winter months was higher than those in spring, summer, and autumn. The IOP difference between winter and summer was (mean +/- sem) 2.9 +/- 0.9 mmHg (p < 0.001). The peak of mean IOP in diurnal variation curve (25.7 +/- 1.2 mmHg) appeared in the morning when the subjects had just awaken. The mean diurnal variation was found to be 4.2 +/- 0.6 mmHg (p < 0.001). This study confirms that seasons influence IOP and it shows diurnal variations. As compared to other nations, diurnal variations in ocular hypertensive subjects seem to be somewhat less in Pakistan. Knowledge of the seasonal and diurnal variations in IOP may help glaucoma screeners.

Monitoring and analysis of data obtained from moisture temperature recording stations : executive summary.

DOT National Transportation Integrated Search

2001-09-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, seven moisture-temperature...

Variation in predator foraging behavior changes predator-prey spatio-temporal dynamics

USDA-ARS?s Scientific Manuscript database

1. Foraging underlies the ability of all animals to acquire essential resources and, thus, provides a critical link to understanding population dynamics. A key issue is how variation in foraging behavior affects foraging efficiency and predator-prey interactions in spatially-heterogeneous environmen...

Monitoring and analysis of data obtained from moisture temperature recording stations : final report.

DOT National Transportation Integrated Search

2001-09-01

The performance of asphalt concrete pavements is in part affected by the seasonal variations of the resilient modulus of the AC layer and of the subgrade soil. To determine the variation of these parameters throughout Ohio, seven moisture-temperature...

Genetic effects on gene expression across human tissues

PubMed Central

2017-01-01

Characterization of the molecular function of the human genome and its variation across individuals is essential for identifying the cellular mechanisms that underlie human genetic traits and diseases. The Genotype-Tissue Expression (GTEx) project aims to characterize variation in gene expression levels across individuals and diverse tissues of the human body, many of which are not easily accessible. Here we describe genetic effects on gene expression levels across 44 human tissues. We find that local genetic variation affects gene expression levels for the majority of genes, and we further identify inter-chromosomal genetic effects for 93 genes and 112 loci. On the basis of the identified genetic effects, we characterize patterns of tissue specificity, compare local and distal effects, and evaluate the functional properties of the genetic effects. We also demonstrate that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, enabling a mechanistic interpretation of gene regulation and the genetic basis of disease. PMID:29022597

Forest dynamics to precipitation and temperature in the Gulf of Mexico coastal region.

PubMed

Li, Tianyu; Meng, Qingmin

2017-05-01

The forest is one of the most significant components of the Gulf of Mexico (GOM) coast. It provides livelihood to inhabitant and is known to be sensitive to climatic fluctuations. This study focuses on examining the impacts of temperature and precipitation variations on coastal forest. Two different regression methods, ordinary least squares (OLS) and geographically weighted regression (GWR), were employed to reveal the relationship between meteorological variables and forest dynamics. OLS regression analysis shows that changes in precipitation and temperature, over a span of 12 months, are responsible for 56% of NDVI variation. The forest, which is not particularly affected by the average monthly precipitation in most months, is observed to be affected by cumulative seasonal and annual precipitation explicitly. Temperature and precipitation almost equally impact on NDVI changes; about 50% of the NDVI variations is explained in OLS modeling, and about 74% of the NDVI variations is explained in GWR modeling. GWR analysis indicated that both precipitation and temperature characterize the spatial heterogeneity patterns of forest dynamics.

Forest dynamics to precipitation and temperature in the Gulf of Mexico coastal region

NASA Astrophysics Data System (ADS)

Li, Tianyu; Meng, Qingmin

2017-05-01

The forest is one of the most significant components of the Gulf of Mexico (GOM) coast. It provides livelihood to inhabitant and is known to be sensitive to climatic fluctuations. This study focuses on examining the impacts of temperature and precipitation variations on coastal forest. Two different regression methods, ordinary least squares (OLS) and geographically weighted regression (GWR), were employed to reveal the relationship between meteorological variables and forest dynamics. OLS regression analysis shows that changes in precipitation and temperature, over a span of 12 months, are responsible for 56% of NDVI variation. The forest, which is not particularly affected by the average monthly precipitation in most months, is observed to be affected by cumulative seasonal and annual precipitation explicitly. Temperature and precipitation almost equally impact on NDVI changes; about 50% of the NDVI variations is explained in OLS modeling, and about 74% of the NDVI variations is explained in GWR modeling. GWR analysis indicated that both precipitation and temperature characterize the spatial heterogeneity patterns of forest dynamics.

Genetic effects on gene expression across human tissues.

PubMed

Battle, Alexis; Brown, Christopher D; Engelhardt, Barbara E; Montgomery, Stephen B

2017-10-11

Characterization of the molecular function of the human genome and its variation across individuals is essential for identifying the cellular mechanisms that underlie human genetic traits and diseases. The Genotype-Tissue Expression (GTEx) project aims to characterize variation in gene expression levels across individuals and diverse tissues of the human body, many of which are not easily accessible. Here we describe genetic effects on gene expression levels across 44 human tissues. We find that local genetic variation affects gene expression levels for the majority of genes, and we further identify inter-chromosomal genetic effects for 93 genes and 112 loci. On the basis of the identified genetic effects, we characterize patterns of tissue specificity, compare local and distal effects, and evaluate the functional properties of the genetic effects. We also demonstrate that multi-tissue, multi-individual data can be used to identify genes and pathways affected by human disease-associated variation, enabling a mechanistic interpretation of gene regulation and the genetic basis of disease.

The effects of oil spills on marine fish: Implications of spatial variation in natural mortality.

PubMed

Langangen, Ø; Olsen, E; Stige, L C; Ohlberger, J; Yaragina, N A; Vikebø, F B; Bogstad, B; Stenseth, N C; Hjermann, D Ø

2017-06-15

The effects of oil spills on marine biological systems are of great concern, especially in regions with high biological production of harvested resources such as in the Northeastern Atlantic. The scientific studies of the impact of oil spills on fish stocks tend to ignore that spatial patterns of natural mortality may influence the magnitude of the impact over time. Here, we first illustrate how spatial variation in natural mortality may affect the population impact by considering a thought experiment. Second, we consider an empirically based example of Northeast Arctic cod to extend the concept to a realistic setting. Finally, we present a scenario-based investigation of how the degree of spatial variation in natural mortality affects the impact over a gradient of oil spill sizes. Including the effects of spatial variations in natural mortality tends to widen the impact distribution, hence increasing the probability of both high and low impact events. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

The Growing Phenomenon of School Gardens: Measuring Their Variation and Their Affect on Students' Sense of Responsibility and Attitudes toward Science and the Environment

ERIC Educational Resources Information Center

Skelly, Sonja M.; Bradley, Jennifer Campbell

2007-01-01

This article summarizes a 2000 study of school garden programs and their variation and the impact of such variation on 427 third-grade students' sense of responsibility and attitudes toward science and the environment. A teacher questionnaire was developed to gain insight into how teachers use school gardens with their students and in their…

Comparing intra- and inter-specific effects on litter decomposition in an old-field ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crutsinger, Greg; Sanders, Dr. Nathan James; Classen, Aimee T

2009-09-01

Plant species can differ in the quantity and quality of leaf litter they produce, and many studies have examined whether plant species diversity affects leaf-litter decomposition and nutrient release. A growing number of studies have indicated that intra-specific variation within plant species can also affect key ecosystem processes. However, the relative importance of intra- versus inter-specific variation for the functioning of ecosystems remains poorly known. Here, we investigate the effects of intra-specific variation in a dominant old-field plant species, tall goldenrod (Solidago altissima), and inter-specific variation among goldenrod species on litter quality, decomposition, and nitrogen (N) release. We found thatmore » the nutrient concentration of leaf litter varied among genotypes, which translated into 50% difference in decomposition rates. Variation among other goldenrod species in decomposition rate was more than twice that of genetic variation within S. altissima. Furthermore, by manipulating litterbags to contain 1, 3, 6, or 9 genotypes, we found that S. altissima genotype identity had much stronger effects than did genotypic diversity on leaf-litter quality, decomposition, and N release. Taken together, these results suggest that the order of ecological importance for controlling leaf-litter decomposition and N release dynamics is plant species identitygenotype identity>genotypic diversity.« less

Numerical Analysis of Residual Stress and Distortion Use Finite Element Method on Inner Bottom Construction of Geomarin IV Survey Ship with Welding Sequence Variations

NASA Astrophysics Data System (ADS)

Syahroni, N.; Hartono, A. B. W.; Murtedjo, M.

2018-03-01

In the ship fabrication industry, welding is the most critical stage. If the quality of welding on ship fabrication is not good, then it will affect the strength and overall appearance of the structure. One of the factors that affect the quality of welding is residual stress and distortion. In this research welding simulation is performed on the inner bottom construction of Geomarin IV Ship Survey using shell element and has variation to welding sequence. In this study, welding simulations produced peak temperatures at 2490 K at variation 4. While the lowest peak temperature was produced by variation 2 with a temperature of 2339 K. After welding simulation, it continued simulating residual stresses and distortion. The smallest maximum tensile residual stress found in the inner bottom construction is 375.23 MPa, and the maximum tensile pressure is -20.18 MPa. The residual stress is obtained from variation 3. The distortion occurring in the inner bottom construction for X=720 mm is 4.2 mm and for X=-720 mm, the distortion is 4.92 mm. The distortion is obtained from the variation 3. Near the welding area, distortion value reaches its minimum point. This is because the stiffeners in the form of frames serves as anchoring.

Hedgehog signaling mediates adaptive variation in a dynamic functional system in the cichlid feeding apparatus.

PubMed

Hu, Yinan; Albertson, R Craig

2014-06-10

Adaptive variation in the craniofacial skeleton is a key component of resource specialization and habitat divergence in vertebrates, but the proximate genetic mechanisms that underlie complex patterns of craniofacial variation are largely unknown. Here we demonstrate that the Hedgehog (Hh) signaling pathway mediates widespread variation across a complex functional system that affects the kinematics of lower jaw depression--the opercular four-bar linkage apparatus--among Lake Malawi cichlids. By using a combined quantitative trait locus mapping and population genetics approach, we show that allelic variation in the Hh receptor, ptch1, affects the development of distinct bony elements in the head that represent two of three movable links in this functional system. The evolutionarily derived allele is found in species that feed from the water column, and is associated with shifts in anatomy that translate to a four-bar system capable of faster jaw rotation. Alternatively, the ancestral allele is found in species that feed on attached algae, and is associated with the development of a four-bar system that predicts slower jaw movement. Experimental manipulation of the Hh pathway during cichlid development recapitulates functionally salient natural variation in craniofacial geometry. In all, these results significantly extend our understanding of the mechanisms that fine-tune the craniofacial skeletal complex during adaptation to new foraging niches.

Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil.

PubMed

Filho, J A Araujo; Brito, S V; Lima, V F; Pereira, A M A; Mesquita, D O; Albuquerque, R L; Almeida, W O

2017-05-01

Ecological characteristics and environmental variation influence both host species composition and parasite abundance. Abiotic factors such as rainfall and temperature can improve parasite development and increase its reproduction rate. The comparison of these assemblages between different environments may give us a more refined analysis of how environment affects the variation of helminth parasite abundance. The aim of the present study was to evaluate how temporal variation, host size, sex and reproduction affect helminth abundance in the Tropidurus hispidus lizard in Caatinga, Restinga and Atlantic Forest environments. Overall, larger-sized lizards showed higher helminth abundance. We found a monthly variation in the helminth species abundance in all studied areas. In the Caatinga area, monoxenic and heteroxenic parasites were related to the rainy season and to the reproductive period of lizards. In Restinga, monoxenic and heteroxenic helminth species were more abundant during the driest months. In the Atlantic Forest, the rainy and host reproductive season occurred continuously throughout the year, so parasite abundance was relatively constant. Nevertheless, heteroxenic species were more abundant in this area. The present results showed that the temporal variation, body size, sex, reproductive period and habitat type influence the abundance and composition of helminth species in T. hispidus.

Affective states and adaptation to parabolic flights

NASA Astrophysics Data System (ADS)

Collado, Aurélie; Langlet, Cécile; Tzanova, Tzvetomira; Hainaut, Jean-Philippe; Monfort, Vincent; Bolmont, Benoît

2017-05-01

This exploratory study investigates (i) inter-individual variations of affective states before a parabolic flight (i.e., PF) on the basis of quality of adaptation to physical demands, and (ii) intra-individual variations of affective states during a PF. Mood-states, state-anxiety and salivary cortisol were assessed in two groups with a different quality of adaptation (an Adaptive Group, i.e., AG, and a Maladaptive Group, i.e., MG) before and during a PF. Before PF, MG scored higher on mood states (Anger-Hostility, Fatigue-Inertia) than AG. During the flight, while AG seemed to present "normal" affective responses to the demanding environment (e.g., increase in salivary cortisol), MG presented increases in mood states such as Confusion-Bewilderment or Tension-Anxiety. The findings suggest that the psychological states of MG could have disturbed their ability to integrate sensory information from an unusual environment, which led to difficulties in coping with the physical demands of PF.

The contribution of developmental experience vs. condition to life history, trait variation, and individual differences

PubMed Central

DiRienzo, Nicholas; Montiglio, Pierre-Olivier

2016-01-01

SUMMARY Developmental experience, for example food abundance during juvenile stages, is known to affect life history and behaviour. However, the life history and behavioural consequences of developmental experience have rarely been studied in concert. As a result it is still unclear whether developmental experience affects behaviour through changes in life history, or independently of it.The effect of developmental experience on life history and behaviour may also be masked or affected by individual condition during adulthood. Thus, it is critical to tease apart the effects of developmental experience and current individual condition on life history and behaviour.In this study we manipulated food abundance during development in the western black widow spider, Latrodectus hesperus, by rearing spiders on either a restricted or ad lib diet. We separated developmental from condition dependent effects by assaying adult foraging behaviour (tendency to attack prey and to stay on out of the refuge following an attack) and web structure multiple times under different levels of satiation following different developmental treatments.Spiders reared under food restriction matured slower and at a smaller size than spiders reared in ad lib conditions. Spiders reared on a restricted diet were more aggressive towards prey and built webs structured for prey capture while spiders reared on an ad lib diet were less aggressive and build safer webs. Developmental treatment affected which traits were plastic as adults: restricted spiders built safer webs when their adult condition increased, while ad-lib spiders reduced their aggression when their adult condition increased. The amount of individual variation in behaviour and web structure varied with developmental treatment. Spiders reared on a restricted diet exhibited consistent variation in all aspects of foraging behaviour and web structure, while spiders reared on an ad lib diet exhibited consistent individual variation in aggression and web weight only.Developmental experience affected the average life history, behaviour, and web structure of spiders, but also shaped the amount of phenotypic variation observed among individuals. Surprisingly, developmental experience also determined the particular way in which individuals plastically adjusted their behaviour and web structure to changes in adult condition. PMID:26937627

Limited phenotypic variation of hypocalcified amelogenesis imperfecta in a Danish five-generation family with a novel FAM83H nonsense mutation.

PubMed

Haubek, Dorte; Gjørup, Hans; Jensen, Lillian G; Juncker, Inger; Nyegaard, Mette; Børglum, Anders D; Poulsen, Sven; Hertz, Jens M

2011-11-01

BACKGROUND.  Autosomal dominant hypocalcified amelogenesis imperfecta (ADHCAI) is a disease with severe dental manifestations. OBJECTIVES.  The aims were by means of a genome-wide linkage scan to search for the gene underlying the ADHCAI phenotype in a Danish five-generation family and to study the phenotypic variation of the enamel in affected family members. RESULTS.  Significant linkage was found to a locus at chromosome 8q24.3 comprising the gene FAM83H identified to be responsible for ADHCAI in other families. Subsequent sequencing of FAM83H in affected family members revealed a novel nonsense mutation, p.Y302X. Limited phenotypic variation was found among affected family members with loss of translucency and discoloration of the enamel. Extensive posteruptive loss of enamel was found in all teeth of affected subjects. The tip of the cusps on the premolars and molars and a zone along the gingival margin seemed resistant to posteruptive loss of enamel. We have screened FAM83H in another five unrelated Danish patients with a phenotype of ADHCAI similar to that in the five-generation family, and identified a de novo FAM83H nonsense mutation, p.Q452X in one of these patients. CONCLUSION.  We have identified a FAM83H mutation in two of six unrelated families with ADHCAI and found limited phenotypic variation of the enamel in these patients. © 2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.

Missense SLC25A38 variations play an important role in autosomal recessive inherited sideroblastic anemia

PubMed Central

Kannengiesser, Caroline; Sanchez, Mayka; Sweeney, Marion; Hetet, Gilles; Kerr, Briedgeen; Moran, Erica; Fuster Soler, Jose L.; Maloum, Karim; Matthes, Thomas; Oudot, Caroline; Lascaux, Axelle; Pondarré, Corinne; Sevilla Navarro, Julian; Vidyatilake, Sudharma; Beaumont, Carole; Grandchamp, Bernard; May, Alison

2011-01-01

Background Congenital sideroblastic anemias are rare disorders with several genetic causes; they are characterized by erythroblast mitochondrial iron overload, differ greatly in severity and some occur within a syndrome. The most common cause of non-syndromic, microcytic sideroblastic anemia is a defect in the X-linked 5-aminolevulinate synthase 2 gene but this is not always present. Recently, variations in the gene for the mitochondrial carrier SLC25A38 were reported to cause a non-syndromic, severe type of autosomal-recessive sideroblastic anemia. Further evaluation of the importance of this gene was required to estimate the proportion of patients affected and to gain further insight into the range and types of variations involved. Design and Methods In three European diagnostic laboratories sequence analysis of SLC25A38 was performed on DNA from patients affected by congenital sideroblastic anemia of a non-syndromic nature not caused by variations in the 5-aminolevulinate synthase 2 gene. Results Eleven patients whose ancestral origins spread across several continents were homozygous or compound heterozygous for ten different SLC25A38 variations causing premature termination of translation (p.Arg117X, p.Tyr109LeufsX43), predicted splicing alteration (c.625G>C; p.Asp209His) or missense substitution (p.Gln56Lys, p.Arg134Cys, p.Ile147Asn, p.Arg187Gln, p.Pro190Arg, p.Gly228Val, p.Arg278Gly). Only three of these variations have been described previously (p.Arg117X, p.Tyr109LeufsX43 and p.Asp209His). All new variants reported here are missense and affect conserved amino acids. Structure modeling suggests that these variants may influence different aspects of transport as described for mutations in other mitochondrial carrier disorders. Conclusions Mutations in the SLC25A38 gene cause severe, non-syndromic, microcytic/hypochromic sideroblastic anemia in many populations. Missense mutations are shown to be of importance as are mutations that affect protein production. Further investigation of these mutations should shed light on structure-function relationships in this protein. PMID:21393332

40 CFR 264.345 - Operating requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... variations in the physical or chemical properties of the waste feed which will not affect compliance with the... (CO) level in the stack exhaust gas; (2) Waste feed rate; (3) Combustion temperature; (4) An appropriate indicator of combustion gas velocity; (5) Allowable variations in incinerator system design or...

Seed dormancy in Mexican teosinte

USDA-ARS?s Scientific Manuscript database

Seed dormancy in wild Zea species may affect fitness and relate to ecological adaptation. The primary objective of this study was to characterize the variation in seed germination of the wild species of the genus Zea that currently grow in Mexico, and to relate this variation to their ecological zon...

Evolutionary consequences of habitat loss for Pacific anadromous salmonids

PubMed Central

McClure, Michelle M; Carlson, Stephanie M; Beechie, Timothy J; Pess, George R; Jorgensen, Jeffrey C; Sogard, Susan M; Sultan, Sonia E; Holzer, Damon M; Travis, Joseph; Sanderson, Beth L; Power, Mary E; Carmichael, Richard W

2008-01-01

Large portions of anadromous salmonid habitat in the western United States has been lost because of dams and other blockages. This loss has the potential to affect salmonid evolution through natural selection if the loss is biased, affecting certain types of habitat differentially, and if phenotypic traits correlated with those habitat types are heritable. Habitat loss can also affect salmonid evolution indirectly, by reducing genetic variation and changing its distribution within and among populations. In this paper, we compare the characteristics of lost habitats with currently accessible habitats and review the heritability of traits which show correlations with habitat/environmental gradients. We find that although there is some regional variation, inaccessible habitats tend to be higher in elevation, wetter and both warmer in the summer and colder in the winter than habitats currently available to anadromous salmonids. We present several case studies that demonstrate either a change in phenotypic or life history expression or an apparent reduction in genetic variation associated with habitat blockages. These results suggest that loss of habitat will alter evolutionary trajectories in salmonid populations and Evolutionarily Significant Units. Changes in both selective regime and standing genetic diversity might affect the ability of these taxa to respond to subsequent environmental perturbations. Both natural and anthropogenic and should be considered seriously in developing management and conservation strategies. PMID:25567633

Cyclone tolerance in new world arecaceae: biogeographic variation and abiotic natural selection.

PubMed

Griffith, M Patrick; Noblick, Larry R; Dowe, John L; Husby, Chad E; Calonje, Michael A

2008-10-01

Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0.001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas.

Accommodating Variation: Dialects, Idiolects, and Speech Processing

PubMed Central

Kraljic, Tanya; Brennan, Susan E.; Samuel, Arthur G.

2008-01-01

Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production. PMID:17803986

Accommodating variation: dialects, idiolects, and speech processing.

PubMed

Kraljic, Tanya; Brennan, Susan E; Samuel, Arthur G

2008-04-01

Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production.

Temporal variation in fault friction and its effects on the slip evolution of a thrust fault over several earthquake cycles

NASA Astrophysics Data System (ADS)

Hampel, Andrea; Hetzel, Ralf

2013-04-01

The friction coefficient is a key parameter for the slip evolution of faults, but how temporal changes in friction affect fault slip is still poorly known. By using three-dimensional numerical models with a thrust fault that is alternately locked and released, we show that variations in the friction coefficient affect both coseismic and long-term fault slip (Hampel and Hetzel, 2012). Decreasing the friction coefficient by 5% while keeping the duration of the interseismic phase constant leads to a four-fold increase in coseismic slip, whereas a 5% increase nearly suppresses slip. A gradual decrease or increase of friction over several earthquake cycles (1-5% per earthquake) considerably alters the cumulative fault slip. In nature, the slip deficit (surplus) resulting from variations in the friction coefficient would presumably be compensated by a longer (shorter) interseismic phase, but the magnitude of the changes required for compensation render variations of the friction coefficient of >5% unlikely. Reference Hampel, A., R. Hetzel (2012) Temporal variation in fault friction and its effects on the slip evolution of a thrust fault over several earthquake cycles. Terra Nova, 24, 357-362, doi: 10.1111/j.1365-3121.2012.01073.x.

Research participant compensation: A matter of statistical inference as well as ethics.

PubMed

Swanson, David M; Betensky, Rebecca A

2015-11-01

The ethics of compensation of research subjects for participation in clinical trials has been debated for years. One ethical issue of concern is variation among subjects in the level of compensation for identical treatments. Surprisingly, the impact of variation on the statistical inferences made from trial results has not been examined. We seek to identify how variation in compensation may influence any existing dependent censoring in clinical trials, thereby also influencing inference about the survival curve, hazard ratio, or other measures of treatment efficacy. In simulation studies, we consider a model for how compensation structure may influence the censoring model. Under existing dependent censoring, we estimate survival curves under different compensation structures and observe how these structures induce variability in the estimates. We show through this model that if the compensation structure affects the censoring model and dependent censoring is present, then variation in that structure induces variation in the estimates and affects the accuracy of estimation and inference on treatment efficacy. From the perspectives of both ethics and statistical inference, standardization and transparency in the compensation of participants in clinical trials are warranted. Copyright © 2015 Elsevier Inc. All rights reserved.

The comparison of SRs' variation affected by solar events observed in America and in China

NASA Astrophysics Data System (ADS)

Yu, H.; Williams, E.

2017-12-01

Schumann Resonances(SRs) are the electromagnetic resonance wave propagating in the earth-ionosphere cavity. Its characteristic of propagation are modified by the variation of ionosphere. So SRs can be the tools of monitoring the ionosphere which is often perturbed by solar events, x-ray emission and some other space-weather events (Roldugin et.al., 2004, De et al., 2010; Satori et.al., 2015). In present work, the amplitude and intrinsic frequencies of SRs observed at RID station in America and YSH station in China are compared. The variation of SRs during the solar flare on Feb. 15, 2011 are analyzed. Two-Dimensional Telegraph Equation(TDTE) method is used to simulate the perturbation of ionosphere by solar proton events. From the simulation and observation, the asymmetric construction of ionoshphere which is perturbed by the solar event will affect the amplitudes and frequencies of SRs. Due to the interfere influence of forward and backward propagation of electromagnetic field, the SR amplitude on different station will present different variation. The distance among the lightning source, observer and perturbed area will produce the different variation of amplitude and frequency for different station' SR.

Plasticity as Phenotype: G x E Interaction in a Freshwater Snail

NASA Astrophysics Data System (ADS)

Brunkow, P. E.; Calloway, S. A.

2005-05-01

Plasticity in morphological development allows species to accommodate environmental variation experienced during growth; however, genetic variation for phenotypic plasticity per se has been relatively under-studied. We utilized the well-documented plastic response of shell development to predator cues in a freshwater snail to quantify genetic variation for plasticity in growth rate and shell shape. Field-caught pairs of snails reproduced in the laboratory to create families of full siblings, which were then divided and allowed to grow in control and predator cue treatments. Predator (crayfish) cues had significant effects on both size-corrected growth rate and shell shape; family identity also significantly affected both final shell shape and growth rate. The interaction between predator treatment and family identity significantly affected snail growth rate but not final shell shape, suggesting genetic variation in the plastic response to predator cues for a physiological variable (growth rate) but not for a variable known to mechanically reduce the risk of predation (shell shape), at least in this population of snails. The possibility that risk of multiple modes of predation (i.e., both fish and crayfish) in some populations might maintain genetic variation in morphological plasticity is discussed.

Copy number variation of individual cattle genomes using next-generation sequencing

USDA-ARS?s Scientific Manuscript database

Copy number variations (CNVs) affect a wide range of phenotypic traits; however, CNVs in or near segmental duplication regions are often intractable. Using a read depth approach based on next-generation sequencing, we examined genome-wide copy number differences among five taurine (three Angus, one ...

Copy number variation of individual cattle genomes using next-generation sequencing

USDA-ARS?s Scientific Manuscript database

Copy Number Variations (CNVs) affect a wide range of phenotypic traits; however, CNVs in or near segmental duplication regions are often difficult to track. Using a read depth approach based on next generation sequencing, we examined genome-wide copy number differences among five taurine (three Angu...

Quantitative trait loci analyses and RNA-seq identify genes affecting stress response in rainbow trout

USDA-ARS?s Scientific Manuscript database

Genomic analyses have the potential to impact aquaculture production traits by identifying markers as proxies for traits which are expensive or difficult to measure and characterizing genetic variation and biochemical mechanisms underlying phenotypic variation. One such trait is the response of rai...

Effects of source and seasonal variations of natural organic matters on the fate and transport of CeO2 nanoparticles in the environment

EPA Science Inventory

Natural organic matter (NOM) affects the stability and transport of nanoparticles (NPs) in natural waters by modifying their physiochemical properties. Source location, and seasonal variations, influence their molecular, physical and electrical charge properties. To understand th...

Elevated CO2 affects plant responses to variation in boron availability

USDA-ARS?s Scientific Manuscript database

Effects of elevated CO2 on N relations are well studied, but effects on other nutrients, especially micronutrients, are not. We investigated effects of elevated CO2 on response to variation in boron (B) availability in three unrelated species: geranium (Pelargonium x hortorum), barley (Hordeum vulga...

The interplay between daily affect and sleep: a 2-week study of young women.

PubMed

Kalmbach, David A; Pillai, Vivek; Roth, Thomas; Drake, Christopher L

2014-12-01

Little attention has been paid to the relation between daily affect and sleep, as most prior studies have focused instead on the role of pathological mood in the context of sleep disturbance. However, understanding the transaction between normal variations in emotional experiences and sleep can shed light on the premorbid vulnerabilities that trigger the evolution of affect and sleep into more problematic states. The present study used a 2-week daily sampling approach to examine the impact of day-to-day variations in positive and negative affect on nightly self-reported sleep-onset latency, sleep duration and sleep quality in a sample of young women. Hierarchical linear modelling revealed temporal relations between positive and negative affect states and sleep parameters. Specifically, different aspects of both positive and negative affect were uniquely predictive of sleep indices, with sadness and serenity acting as the most consistent predictors. Additionally, better sleep quality was predictive of greater happiness the following day. These results highlight the importance of how our daily emotional experiences influence our nightly sleep and, in turn, how our sleep has an impact on our daily affect. Moreover, our findings may offer insight into the progression of normative levels of affect and sleep as they develop into comorbid depression, anxiety and insomnia. © 2014 European Sleep Research Society.

When can preheating affect the CMB?

NASA Astrophysics Data System (ADS)

Tsujikawa, Shinji; Bassett, Bruce A.

2002-05-01

We discuss the principles governing the selection of inflationary models for which preheating can affect the CMB. This is a (fairly small) subset of those models which have nonnegligible entropy/isocurvature perturbations on large scales during inflation. We study new models which belong to this class-two-field inflation with negative nonminimal coupling and hybrid/double/supernatural inflation models where the tachyonic growth of entropy perturbations can lead to the variation of the curvature perturbation, /R, on super-Hubble scales. Finally, we present evidence against recent claims for the variation of /R in the absence of substantial super-Hubble entropy perturbations.

Physiological variations in levels of 2,3-diphosphoglycerate in horse erythrocytes.

PubMed

Lewis, I M; McLan, J G

1975-03-01

The levels of 2,3-diphosphoglycerate (2,3-DPG), which affects the transport of oxygen by haemoglobin, were examined in horse blood. Resting levels of erythrocyte 2,3-DPG were established in thoroughbred horses, and levels of 2,3-DPG together with haemoglobin levels, were examined in a variety of conditions. A negative correlation was observed between erythrocyte 2,3-DPG and haemoglobin levels. Mares had higher erythrocyte 2,3-DPG levels was observed during training, and this variation may have a significant effect on haemoglobin oxygen transport. Erythrocyte 2,3-DPG levels were not affected by age or exercise.

Decay assessment through thermographic analysis in architectural and archaeological heritage

NASA Astrophysics Data System (ADS)

Gomez-Heras, Miguel; Martinez-Perez, Laura; Fort, Rafael; Alvarez de Buergo, Monica

2010-05-01

Any exposed stone-built structure is subject to thermal variations due to daily, seasonal and secular environmental temperature changes. Surface temperature is a function of air temperature (due to convective heat transfer) and of infrared radiation received through insolation. While convective heat transfer homogenizes surface temperature, stone response to insolation is much more complex and the temporal and spatial temperature differences across structures are enhanced. Surface temperature in stone-built structures will be affected by orientation, sunlight inclination and the complex patterns of light and shadows generated by the often intricate morphology of historical artefacts and structures. Surface temperature will also be affected by different material properties, such as albedo, thermal conductivity, transparency and absorbance to infrared radiation of minerals and rocks. Moisture and the occurrence of salts will also be a factor affecting surface temperatures. Surface temperatures may as well be affected by physical disruptions of rocks due to differences in thermal inertia generated by cracks and other discontinuities. Thermography is a non-invasive, non-destructive technique that measures temperature variations on the surface of a material. With this technique, surface temperature rates of change and their spatial variations can be analysed. This analysis may be used not only to evaluate the incidence of thermal decay as a factor that generates or enhances stone decay, but also to detect and evaluate other factors that affect the state of conservation of architectural and archaeological heritage, as for example moisture, salts or mechanical disruptions.

Long-Range Regulatory Polymorphisms Affecting a GABA Receptor Constitute a Quantitative Trait Locus (QTL) for Social Behavior in Caenorhabditis elegans

PubMed Central

Bendesky, Andres; Pitts, Jason; Rockman, Matthew V.; Chen, William C.; Tan, Man-Wah; Kruglyak, Leonid; Bargmann, Cornelia I.

2012-01-01

Aggregation is a social behavior that varies between and within species, providing a model to study the genetic basis of behavioral diversity. In the nematode Caenorhabditis elegans, aggregation is regulated by environmental context and by two neuromodulatory pathways, one dependent on the neuropeptide receptor NPR-1 and one dependent on the TGF-β family protein DAF-7. To gain further insight into the genetic regulation of aggregation, we characterize natural variation underlying behavioral differences between two wild-type C. elegans strains, N2 and CB4856. Using quantitative genetic techniques, including a survey of chromosome substitution strains and QTL analysis of recombinant inbred lines, we identify three new QTLs affecting aggregation in addition to the two known N2 mutations in npr-1 and glb-5. Fine-mapping with near-isogenic lines localized one QTL, accounting for 5%–8% of the behavioral variance between N2 and CB4856, 3′ to the transcript of the GABA neurotransmitter receptor gene exp-1. Quantitative complementation tests demonstrated that this QTL affects exp-1, identifying exp-1 and GABA signaling as new regulators of aggregation. exp-1 interacts genetically with the daf-7 TGF-β pathway, which integrates food availability and population density, and exp-1 mutations affect the level of daf-7 expression. Our results add to growing evidence that genetic variation affecting neurotransmitter receptor genes is a source of natural behavioral variation. PMID:23284308

Experimental shifts in intraclutch egg color variation do not affect egg rejection in a host of a non-egg-mimetic avian brood parasite.

PubMed

Croston, Rebecca; Hauber, Mark E

2015-01-01

Avian brood parasites lay their eggs in the nests of other birds, and impose the costs associated with rearing parasitic young onto these hosts. Many hosts of brood parasites defend against parasitism by removing foreign eggs from the nest. In systems where parasitic eggs mimic host eggs in coloration and patterning, extensive intraclutch variation in egg appearances may impair the host's ability to recognize and reject parasitic eggs, but experimental investigation of this effect has produced conflicting results. The cognitive mechanism by which hosts recognize parasitic eggs may vary across brood parasite hosts, and this may explain variation in experimental outcome across studies investigating egg rejection in hosts of egg-mimicking brood parasites. In contrast, for hosts of non-egg-mimetic parasites, intraclutch egg color variation is not predicted to co-vary with foreign egg rejection, irrespective of cognitive mechanism. Here we tested for effects of intraclutch egg color variation in a host of nonmimetic brood parasite by manipulating egg color in American robins (Turdus migratorius), hosts of brown-headed cowbirds (Molothrus ater). We recorded robins' behavioral responses to simulated cowbird parasitism in nests where color variation was artificially enhanced or reduced. We also quantified egg color variation within and between unmanipulated robin clutches as perceived by robins themselves using spectrophotometric measures and avian visual modeling. In unmanipulated nests, egg color varied more between than within robin clutches. As predicted, however, manipulation of color variation did not affect rejection rates. Overall, our results best support the scenario wherein egg rejection is the outcome of selective pressure by a nonmimetic brood parasite, because robins are efficient rejecters of foreign eggs, irrespective of the color variation within their own clutch.

Experimental Shifts in Intraclutch Egg Color Variation Do Not Affect Egg Rejection in a Host of a Non-Egg-Mimetic Avian Brood Parasite

PubMed Central

Croston, Rebecca; Hauber, Mark E.

2015-01-01

Avian brood parasites lay their eggs in the nests of other birds, and impose the costs associated with rearing parasitic young onto these hosts. Many hosts of brood parasites defend against parasitism by removing foreign eggs from the nest. In systems where parasitic eggs mimic host eggs in coloration and patterning, extensive intraclutch variation in egg appearances may impair the host’s ability to recognize and reject parasitic eggs, but experimental investigation of this effect has produced conflicting results. The cognitive mechanism by which hosts recognize parasitic eggs may vary across brood parasite hosts, and this may explain variation in experimental outcome across studies investigating egg rejection in hosts of egg-mimicking brood parasites. In contrast, for hosts of non-egg-mimetic parasites, intraclutch egg color variation is not predicted to co-vary with foreign egg rejection, irrespective of cognitive mechanism. Here we tested for effects of intraclutch egg color variation in a host of nonmimetic brood parasite by manipulating egg color in American robins (Turdus migratorius), hosts of brown-headed cowbirds (Molothrus ater). We recorded robins’ behavioral responses to simulated cowbird parasitism in nests where color variation was artificially enhanced or reduced. We also quantified egg color variation within and between unmanipulated robin clutches as perceived by robins themselves using spectrophotometric measures and avian visual modeling. In unmanipulated nests, egg color varied more between than within robin clutches. As predicted, however, manipulation of color variation did not affect rejection rates. Overall, our results best support the scenario wherein egg rejection is the outcome of selective pressure by a nonmimetic brood parasite, because robins are efficient rejecters of foreign eggs, irrespective of the color variation within their own clutch. PMID:25831051

Roles of climate, vegetation and soil in regulating the spatial variations in ecosystem carbon dioxide fluxes in the Northern Hemisphere.

PubMed

Chen, Zhi; Yu, Guirui; Ge, Jianping; Wang, Qiufeng; Zhu, Xianjin; Xu, Zhiwei

2015-01-01

Climate, vegetation, and soil characteristics play important roles in regulating the spatial variation in carbon dioxide fluxes, but their relative influence is still uncertain. In this study, we compiled data from 241 eddy covariance flux sites in the Northern Hemisphere and used Classification and Regression Trees and Redundancy Analysis to assess how climate, vegetation, and soil affect the spatial variations in three carbon dioxide fluxes (annual gross primary production (AGPP), annual ecosystem respiration (ARE), and annual net ecosystem production (ANEP)). Our results showed that the spatial variations in AGPP, ARE, and ANEP were significantly related to the climate and vegetation factors (correlation coefficients, R = 0.22 to 0.69, P < 0.01) while they were not related to the soil factors (R = -0.11 to 0.14, P > 0.05) in the Northern Hemisphere. The climate and vegetation together explained 60% and 58% of the spatial variations in AGPP and ARE, respectively. Climate factors (mean annual temperature and precipitation) could account for 45-47% of the spatial variations in AGPP and ARE, but the climate constraint on the vegetation index explained approximately 75%. Our findings suggest that climate factors affect the spatial variations in AGPP and ARE mainly by regulating vegetation properties, while soil factors exert a minor effect. To more accurately assess global carbon balance and predict ecosystem responses to climate change, these discrepant roles of climate, vegetation, and soil are required to be fully considered in the future land surface models. Moreover, our results showed that climate and vegetation factors failed to capture the spatial variation in ANEP and suggest that to reveal the underlying mechanism for variation in ANEP, taking into account the effects of other factors (such as climate change and disturbances) is necessary.

Roles of Climate, Vegetation and Soil in Regulating the Spatial Variations in Ecosystem Carbon Dioxide Fluxes in the Northern Hemisphere

PubMed Central

Chen, Zhi; Yu, Guirui; Ge, Jianping; Wang, Qiufeng; Zhu, Xianjin; Xu, Zhiwei

2015-01-01

Climate, vegetation, and soil characteristics play important roles in regulating the spatial variation in carbon dioxide fluxes, but their relative influence is still uncertain. In this study, we compiled data from 241 eddy covariance flux sites in the Northern Hemisphere and used Classification and Regression Trees and Redundancy Analysis to assess how climate, vegetation, and soil affect the spatial variations in three carbon dioxide fluxes (annual gross primary production (AGPP), annual ecosystem respiration (ARE), and annual net ecosystem production (ANEP)). Our results showed that the spatial variations in AGPP, ARE, and ANEP were significantly related to the climate and vegetation factors (correlation coefficients, R = 0.22 to 0.69, P < 0.01) while they were not related to the soil factors (R = -0.11 to 0.14, P > 0.05) in the Northern Hemisphere. The climate and vegetation together explained 60 % and 58 % of the spatial variations in AGPP and ARE, respectively. Climate factors (mean annual temperature and precipitation) could account for 45 - 47 % of the spatial variations in AGPP and ARE, but the climate constraint on the vegetation index explained approximately 75 %. Our findings suggest that climate factors affect the spatial variations in AGPP and ARE mainly by regulating vegetation properties, while soil factors exert a minor effect. To more accurately assess global carbon balance and predict ecosystem responses to climate change, these discrepant roles of climate, vegetation, and soil are required to be fully considered in the future land surface models. Moreover, our results showed that climate and vegetation factors failed to capture the spatial variation in ANEP and suggest that to reveal the underlying mechanism for variation in ANEP, taking into account the effects of other factors (such as climate change and disturbances) is necessary. PMID:25928452

Natural Genetic Variation Influences Protein Abundances in C. elegans Developmental Signalling Pathways

PubMed Central

Singh, Kapil Dev; Roschitzki, Bernd; Snoek, L. Basten; Grossmann, Jonas; Zheng, Xue; Elvin, Mark; Kamkina, Polina; Schrimpf, Sabine P.; Poulin, Gino B.; Kammenga, Jan E.; Hengartner, Michael O.

2016-01-01

Complex traits, including common disease-related traits, are affected by many different genes that function in multiple pathways and networks. The apoptosis, MAPK, Notch, and Wnt signalling pathways play important roles in development and disease progression. At the moment we have a poor understanding of how allelic variation affects gene expression in these pathways at the level of translation. Here we report the effect of natural genetic variation on transcript and protein abundance involved in developmental signalling pathways in Caenorhabditis elegans. We used selected reaction monitoring to analyse proteins from the abovementioned four pathways in a set of recombinant inbred lines (RILs) generated from the wild-type strains N2 (Bristol) and CB4856 (Hawaii) to enable quantitative trait locus (QTL) mapping. About half of the cases from the 44 genes tested showed a statistically significant change in protein abundance between various strains, most of these were however very weak (below 1.3-fold change). We detected a distant QTL on the left arm of chromosome II that affected protein abundance of the phosphatidylserine receptor protein PSR-1, and two separate QTLs that influenced embryonic and ionizing radiation-induced apoptosis on chromosome IV. Our results demonstrate that natural variation in C. elegans is sufficient to cause significant changes in signalling pathways both at the gene expression (transcript and protein abundance) and phenotypic levels. PMID:26985669

Extensive Copy Number Variation in Fermentation-Related Genes Among Saccharomyces cerevisiae Wine Strains.

PubMed

Steenwyk, Jacob; Rokas, Antonis

2017-05-05

Due to the importance of Saccharomyces cerevisiae in wine-making, the genomic variation of wine yeast strains has been extensively studied. One of the major insights stemming from these studies is that wine yeast strains harbor low levels of genetic diversity in the form of single nucleotide polymorphisms (SNPs). Genomic structural variants, such as copy number (CN) variants, are another major type of variation segregating in natural populations. To test whether genetic diversity in CN variation is also low across wine yeast strains, we examined genome-wide levels of CN variation in 132 whole-genome sequences of S. cerevisiae wine strains. We found an average of 97.8 CN variable regions (CNVRs) affecting ∼4% of the genome per strain. Using two different measures of CN diversity, we found that gene families involved in fermentation-related processes such as copper resistance ( CUP ), flocculation ( FLO ), and glucose metabolism ( HXT ), as well as the SNO gene family whose members are expressed before or during the diauxic shift, showed substantial CN diversity across the 132 strains examined. Importantly, these same gene families have been shown, through comparative transcriptomic and functional assays, to be associated with adaptation to the wine fermentation environment. Our results suggest that CN variation is a substantial contributor to the genomic diversity of wine yeast strains, and identify several candidate loci whose levels of CN variation may affect the adaptation and performance of wine yeast strains during fermentation. Copyright © 2017 Steenwyk and Rokas.

Genetic Variation in the Vesicular Monoamine Transporter: Preliminary associations with Cognitive Outcomes after Severe Traumatic Brain Injury

PubMed Central

Markos, Steven; Failla, Michelle D.; Ritter, Anne C; Dixon, C. Edward; Conley, Yvette P.; Ricker, Joseph H; Arenth, Patricia M.; Juengst, Shannon B.; Wagner, Amy K.

2015-01-01

Introduction Traumatic brain injury (TBI) frequently results in impaired cognition, a function that can be modulated by monoaminergic signaling. Genetic variation among monoaminergic genes may affect post-TBI cognitive performance. The vesicular monoamine transporter 2 (VMAT2) gene may be a novel source of genetic variation important for cognitive outcomes post-TBI given VMAT2’s role in monoaminergic neurotransmission. Objective Evaluate associations between VMAT2 variability and cognitive outcomes post-TBI. Methods We evaluated 136 white adults with severe TBI for variation in VMAT2 using a tagging single nucleotide polymorphism (tSNP) approach (rs363223, rs363226, rs363251, and rs363341). We show genetic variation interacts with assessed cognitive impairment [cognitive composite T-scores (Comp-Cog)] to influence functional cognition [Functional Independence Measure Cognitive subscale (FIM-Cog)] 6 and 12 months post-injury. Results Multivariate analyses at 6-months post-injury showed rs363226 genotype was associated with Comp-Cog (p=0.040) and interacted with Comp-Cog to influence functional cognition (p<0.001). G-homozygotes had the largest cognitive impairment, and their cognitive impairment had the greatest adverse effect on functional cognition. Discussion We provide the first evidence that genetic variation within VMAT2 is associated with cognitive outcomes following TBI. Further work is needed to validate this finding and elucidate mechanisms by which genetic variation affects monoaminergic signaling, mediating differences in cognitive outcomes. PMID:26828714

Ecological effects of aphid abundance, genotypic variation, and contemporary evolution on plants.

PubMed

Turley, Nash E; Johnson, Marc T J

2015-07-01

Genetic variation and contemporary evolution within populations can shape the strength and nature of species interactions, but the relative importance of these forces compared to other ecological factors is unclear. We conducted a field experiment testing the effects of genotypic variation, abundance, and presence/absence of green peach aphids (Myzus persicae) on the growth, leaf nitrogen, and carbon of two plant species (Brassica napus and Solanum nigrum). Aphid genotype affected B. napus but not S. nigrum biomass explaining 20 and 7% of the total variation, respectively. Averaging across both plant species, the presence/absence of aphids had a 1.6× larger effect size (Cohen's d) than aphid genotype, and aphid abundance had the strongest negative effects on plant biomass explaining 29% of the total variation. On B. napus, aphid genotypes had different effects on leaf nitrogen depending on their abundance. Aphids did not influence leaf nitrogen in S. nigrum nor leaf carbon in either species. We conducted a second experiment in the field to test whether contemporary evolution could affect plant performance. Aphid populations evolved in as little as five generations, but the rate and direction of this evolution did not consistently vary between plant species. On one host species (B. napus), faster evolving populations had greater negative effects on host plant biomass, with aphid evolutionary rate explaining 23% of the variation in host plant biomass. Together, these results show that genetic variation and evolution in an insect herbivore can play important roles in shaping host plant ecology.

Out of the Pacific and back again: insights into the matrilineal history of Pacific killer whale ecotypes.

PubMed

Foote, Andrew D; Morin, Phillip A; Durban, John W; Willerslev, Eske; Orlando, Ludovic; Gilbert, M Thomas P

2011-01-01

Killer whales (Orcinus orca) are the most widely distributed marine mammals and have radiated to occupy a range of ecological niches. Disparate sympatric types are found in the North Atlantic, Antarctic and North Pacific oceans, however, little is known about the underlying mechanisms driving divergence. Previous phylogeographic analysis using complete mitogenomes yielded a bifurcating tree of clades corresponding to described ecotypes. However, there was low support at two nodes at which two Pacific and two Atlantic clades diverged. Here we apply further phylogenetic and coalescent analyses to partitioned mitochondrial genome sequences to better resolve the pattern of past radiations in this species. Our phylogenetic reconstructions indicate that in the North Pacific, sympatry between the maternal lineages that make up each ecotype arises from secondary contact. Both the phylogenetic reconstructions and a clinal decrease in diversity suggest a North Pacific to North Atlantic founding event, and the later return of killer whales to the North Pacific. Therefore, ecological divergence could have occurred during the allopatric phase through drift or selection and/or may have either commenced or have been consolidated upon secondary contact due to resource competition. The estimated timing of bidirectional migration between the North Pacific and North Atlantic coincided with the previous inter-glacial when the leakage of fauna from the Indo-Pacific into the Atlantic via the Agulhas current was particularly vigorous.

Spatio-temporal changes in the structure of an Australian frog hybrid zone: a 40-year perspective.

PubMed

Smith, Katie L; Hale, Joshua M; Gay, Laurène; Kearney, Michael; Austin, Jeremy J; Parris, Kirsten M; Melville, Jane

2013-12-01

Spatio-temporal studies of hybrid zones provide an opportunity to test evolutionary hypotheses of hybrid zone maintenance and movement. We conducted a landscape genetics study on a classic hybrid zone of the south-eastern Australian frogs, Litoria ewingii and Litoria paraewingi. This hybrid zone has been comprehensively studied since the 1960s, providing the unique opportunity to directly assess changes in hybrid zone structure across time. We compared both mtDNA and male advertisement call data from two time periods (present and 1960s). Clinal analysis of the coincidence (same center) and concordance (same width) of these traits indicated that the center of the hybrid zone has shifted 1 km south over the last 40 years, although the width of the zone and the rate of introgression remained unchanged. The low frequency of hybrids, the strong concordance of clines within a time period, and the small but significant movement across the study period despite significant anthropogenic changes through the region, suggest the hybrid zone is a tension zone located within a low-density trough. Hybrid zone movement has not been considered common in the past but our findings highlight that it should be considered a crucial component to our understanding of evolution. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Racial discrimination: how not to do it.

PubMed

Hochman, Adam

2013-09-01

The UNESCO Statements on Race of the early 1950s are understood to have marked a consensus amongst natural scientists and social scientists that 'race' is a social construct. Human biological diversity was shown to be predominantly clinal, or gradual, not discreet, and clustered, as racial naturalism implied. From the seventies social constructionists added that the vast majority of human genetic diversity resides within any given racialised group. While social constructionism about race became the majority consensus view on the topic, social constructionism has always had its critics. Sesardic (2010) has compiled these criticisms into one of the strongest defences of racial naturalism in recent times. In this paper I argue that Sesardic equivocates between two versions of racial naturalism: a weak version and a strong version. As I shall argue, the strong version is not supported by the relevant science. The weak version, on the other hand, does not contrast properly with what social constructionists think about 'race'. By leaning on this weak view Sesardic's racial naturalism intermittently gains an appearance of plausibility, but this view is too weak to revive racial naturalism. As Sesardic demonstrates, there are new arguments for racial naturalism post-Human Genome Diversity Project. The positive message behind my critique is how to be a social constructionist about race in the post-genomic era. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of sea-level changes on mid-ocean ridge magmatism and implications for emission rates of carbon.

NASA Astrophysics Data System (ADS)

Cerpa, N.; Katz, R. F.; Keller, T.

2017-12-01

Glacial cycles move water between ice sheets and the ocean, and hence cause regional pressure changes in the solid Earth. The rate of sea-level (SL) change during this cycle is comparable to the rate of mantle upwelling beneath mid-ocean ridges (MORs), and hence we expect the induced pressure variations to modify the rate and depth of silicate melting. SL variations may therefore induce changes in the supply and composition of magma at MORs, which could affect the flux of carbon into the climate system. Likewise, the trace-element geochemistry of magmas tapped by ridge volcanism may vary during these cycles due to variations in melt flux. Such variations may have been recorded by sediment-hosted volcanic glass fragments [Ferguson et al., 2017]. We investigate these questions using computational models of melt production and transport in which volatiles participate in the thermodynamics of melting. Published models of the effect of SL on MORs predict up to 10% variation in carbon emission rates for absolute changes in SL of 50-100 m with possible lag times of several tens of kyrs [Burley et al., 2015; Hasenclever et al., 2017]. A major assumption of those models is that water and carbon are passive, incompatible elements. But small concentrations of those volatiles affect the solidus of mantle peridotite and increase the volume of upper mantle undergoing partial melting. Hence the current predictions of variation in MOR carbon emission might be an underestimate. Moreover, published models neglect the effects of volatiles on melt transport. Recents studies have demonstrated that volatiles can induce channelized transport [Keller and Katz 2016], potentially affecting the rate at which carbon is extracted from the mantle. In this study, we investigate the interplay between SL variations, melting, and segregation of volatile-rich melts. We use two-phase magma/mantle dynamics coupled to melting models that treat water and carbon dioxide as thermodynamic components. We compare models of equilibrium and disequilibrium melting to assess the influence of reaction kinetics on magma productivity at MORs during SL variations. Our calculations provide new estimates of the lag and amplitude of carbon emissions during glacial cycles. We address the impact of SL variations on the trace-element composition of magmas.

Effects of temperature variability on community structure in a natural microbial food web.

PubMed

Zander, Axel; Bersier, Louis-Félix; Gray, Sarah M

2017-01-01

Climate change research has demonstrated that changing temperatures will have an effect on community-level dynamics by altering species survival rates, shifting species distributions, and ultimately, creating mismatches in community interactions. However, most of this work has focused on increasing temperature, and still little is known about how the variation in temperature extremes will affect community dynamics. We used the model aquatic community held within the leaves of the carnivorous plant, Sarracenia purpurea, to test how food web dynamics will be affected by high temperature variation. We tested the community response of the first (bacterial density), second (protist diversity and composition), and third trophic level (predator mortality), and measured community respiration. We collected early and late successional stage inquiline communities from S. purpurea from two North American and two European sites with similar average July temperature. We then created a common garden experiment in which replicates of these communities underwent either high or normal daily temperature variation, with the average temperature equal among treatments. We found an impact of temperature variation on the first two, but not on the third trophic level. For bacteria in the high-variation treatment, density experienced an initial boost in growth but then decreased quickly through time. For protists in the high-variation treatment, alpha-diversity decreased faster than in the normal-variation treatment, beta-diversity increased only in the European sites, and protist community composition tended to diverge more in the late successional stage. The mortality of the predatory mosquito larvae was unaffected by temperature variation. Community respiration was lower in the high-variation treatment, indicating a lower ecosystem functioning. Our results highlight clear impacts of temperature variation. A more mechanistic understanding of the effects that temperature, and especially temperature variation, will have on community dynamics is still greatly needed. © 2016 John Wiley & Sons Ltd.

Genotypic richness predicts phenotypic variation in an endangered clonal plant

PubMed Central

Sinclair, Elizabeth A.; Poore, Alistair G.B.; Bain, Keryn F.; Vergés, Adriana

2016-01-01

Declines in genetic diversity within a species can affect the stability and functioning of populations. The conservation of genetic diversity is thus a priority, especially for threatened or endangered species. The importance of genetic variation, however, is dependent on the degree to which it translates into phenotypic variation for traits that affect individual performance and ecological processes. This is especially important for predominantly clonal species, as no single clone is likely to maximise all aspects of performance. Here we show that intraspecific genotypic diversity as measured using microsatellites is a strong predictor of phenotypic variation in morphological traits and shoot productivity of the threatened, predominantly clonal seagrass Posidonia australis, on the east coast of Australia. Biomass and surface area variation was most strongly predicted by genotypic richness, while variation in leaf chemistry (phenolics and nitrogen) was unrelated to genotypic richness. Genotypic richness did not predict tissue loss to herbivores or epiphyte load, however we did find that increased herbivore damage was positively correlated with allelic richness. Although there was no clear relationship between higher primary productivity and genotypic richness, variation in shoot productivity within a meadow was significantly greater in more genotypically diverse meadows. The proportion of phenotypic variation explained by environmental conditions varied among different genotypes, and there was generally no variation in phenotypic traits among genotypes present in the same meadows. Our results show that genotypic richness as measured through the use of presumably neutral DNA markers does covary with phenotypic variation in functionally relevant traits such as leaf morphology and shoot productivity. The remarkably long lifespan of individual Posidonia plants suggests that plasticity within genotypes has played an important role in the longevity of the species. However, the strong link between genotypic and phenotypic variation suggests that a range of genotypes is still the best case scenario for adaptation to and recovery from predicted environmental change. PMID:26925313

Relationships between the floral neighborhood and individual pollen limitation in two self-incompatible herbs.

PubMed

Jakobsson, Anna; Lázaro, Amparo; Totland, Orjan

2009-07-01

Local flower density can affect pollen limitation and plant reproductive success through changes in pollinator visitation and availability of compatible pollen. Many studies have investigated the relationship between conspecific density and pollen limitation among populations, but less is known about within-population relationships and the effect of heterospecific flower density. In addition, few studies have explicitly assessed how the spatial scales at which flowers are monitored affect relationships. We investigated the effect of floral neighborhood on pollen limitation at four spatial scales in the self-incompatible herbs Armeria maritima spp. maritima and Ranunculus acris spp. acris. Moreover, we measured pollen deposition in Armeria and pollinator visits to Ranunculus. There was substantial variation in pollen limitation among Armeria individuals, and 25% of this variation was explained by the density of compatible and heterospecific flowers within a 3 m circle. Deposition of compatible pollen was affected by the density of compatible and incompatible inflorescences within a 0.5 m circle, and deposition of heterospecific pollen was affected by the density of heterospecific flowers within a 2 m circle. In Ranunculus, the number of pollinator visits was affected by both conspecific and heterospecific flower densities. This did not, however, result in effects of the floral neighborhood on pollen limitation, probably due to an absence of pollen limitation at the population level. Our study shows that considerable variation in pollen limitation may occur among individuals of a population, and that this variation is partly explained by floral neighborhood density. Such individual-based measures provide an important link between pollen limitation theory, which predicts ecological and evolutionary causes and consequences for individual plants, and studies of the effects of landscape fragmentation on plant species persistence. Our study also highlights the importance of considering multiple spatial scales to understand the spatial extent of pollination processes within a population.

Blood Mercury Levels of Zebra Finches Are Heritable: Implications for the Evolution of Mercury Resistance

PubMed Central

Buck, Kenton A.; Varian-Ramos, Claire W.; Cristol, Daniel A.; Swaddle, John P.

2016-01-01

Mercury is a ubiquitous metal contaminant that negatively impacts reproduction of wildlife and has many other sub-lethal effects. Songbirds are sensitive bioindicators of mercury toxicity and may suffer population declines as a result of mercury pollution. Current predictions of mercury accumulation and biomagnification often overlook possible genetic variation in mercury uptake and elimination within species and the potential for evolution in affected populations. We conducted a study of dietary mercury exposure in a model songbird species, maintaining a breeding population of zebra finches (Taeniopygia guttata) on standardized diets ranging from 0.0–2.4 μg/g methylmercury. We applied a quantitative genetics approach to examine patterns of variation and heritability of mercury accumulation within dietary treatments using a method of mixed effects modeling known as the 'animal model'. Significant variation in blood mercury accumulation existed within each treatment for birds exposed at the same dietary level; moreover, this variation was highly repeatable for individuals. We observed substantial genetic variation in blood mercury accumulation for birds exposed at intermediate dietary concentrations. Taken together, this is evidence that genetic variation for factors affecting blood mercury accumulation could be acted on by selection. If similar heritability for mercury accumulation exists in wild populations, selection could result in genetic differentiation for populations in contaminated locations, with possible consequences for mercury biomagnification in food webs. PMID:27668745

The affect of tissue depth variation on craniofacial reconstructions.

PubMed

Starbuck, John M; Ward, Richard E

2007-10-25

We examined the affect of tissue depth variation on the reconstruction of facial form, through the application of the American method, utilizing published tissue depth measurements for emaciated, normal, and obese faces. In this preliminary study, three reconstructions were created on reproductions of the same skull for each set of tissue depth measurements. The resulting morphological variation was measured quantitatively using the anthropometric craniofacial variability index (CVI). This method employs 16 standard craniofacial anthropometric measurements and the results reflect "pattern variation" or facial harmony. We report no appreciable variation in the quantitative measure of the pattern facial form obtained from the three different sets of tissue depths. Facial similarity was assessed qualitatively utilizing surveys of photographs of the three reconstructions. Surveys indicated that subjects frequently perceived the reconstructions as representing different individuals. This disagreement indicates that size of the face may blind observers to similarities in facial form. This research is significant because it illustrates the confounding effect that normal human variation contributes in the successful recognition of individuals from a representational three-dimensional facial reconstruction. Research results suggest that successful identification could be increased if multiple reconstructions were created which reflect a wide range of possible outcomes for facial form. The creation of multiple facial images, from a single skull, will be facilitated as computerized versions of facial reconstruction are further developed and refined.

Variations in the Availability of Pollen Resources Affect Honey Bee Health

PubMed Central

Di Pasquale, Garance; Alaux, Cédric; Le Conte, Yves; Odoux, Jean-François; Pioz, Maryline; Vaissière, Bernard E.; Belzunces, Luc P.; Decourtye, Axel

2016-01-01

Intensive agricultural systems often expose honey bees (Apis mellifera L.) to large temporal variations in the availability (quantity, quality and diversity) of nutritional resources. Such nutritional irregularity is expected to affect honey bee health. We therefore tested under laboratory conditions the effect of such variation in pollen availability on honey bee health (survival and nursing physiology—hypopharyngeal gland development and vitellogenin expression). We fed honey bees with different diets composed of pollen pellets collected by honey bees in an agricultural landscape of western France. Slight drops (5–10%) in the availability of oilseed rape (Brassica napus L.) pollen resulted in significant reductions of all tested variables. Despite some variations in taxonomic diversity and nutritional quality, the pollen mixes harvested over the season had a similar positive influence on honey bee health, except for the one collected in late July that induced poor survival and nursing physiology. This period coincided with the mass-flowering of maize (Zea mays L.), an anemophilous crop which produces poor-quality pollen. Therefore, changes in bee health were not connected to variations in pollen diversity but rather to variations in pollen depletion and quality, such as can be encountered in an intensive agricultural system of western France. Finally, even though pollen can be available ad libitum during the mass-flowering of some crops (e.g. maize), it can fail to provide bees with diet adequate for their development. PMID:27631605

Multiple Weather Factors Affect Apparent Survival of European Passerine Birds

PubMed Central

Salewski, Volker; Hochachka, Wesley M.; Fiedler, Wolfgang

2013-01-01

Weather affects the demography of animals and thus climate change will cause local changes in demographic rates. In birds numerous studies have correlated demographic factors with weather but few of those examined variation in the impacts of weather in different seasons and, in the case of migrants, in different regions. Using capture-recapture models we correlated weather with apparent survival of seven passerine bird species with different migration strategies to assess the importance of selected facets of weather throughout the year on apparent survival. Contrary to our expectations weather experienced during the breeding season did not affect apparent survival of the target species. However, measures for winter severity were associated with apparent survival of a resident species, two short-distance/partial migrants and a long-distance migrant. Apparent survival of two short distance migrants as well as two long-distance migrants was further correlated with conditions experienced during the non-breeding season in Spain. Conditions in Africa had statistically significant but relatively minor effects on the apparent survival of the two long-distance migrants but also of a presumably short-distance migrant and a short-distance/partial migrant. In general several weather effects independently explained similar amounts of variation in apparent survival for the majority of species and single factors explained only relatively low amounts of temporal variation of apparent survival. Although the directions of the effects on apparent survival mostly met our expectations and there are clear predictions for effects of future climate we caution against simple extrapolations of present conditions to predict future population dynamics. Not only did weather explains limited amounts of variation in apparent survival, but future demographics will likely be affected by changing interspecific interactions, opposing effects of weather in different seasons, and the potential for phenotypic and microevolutionary adaptations. PMID:23593131

Pathogen and host genotype differently affect pathogen fitness through their effects on different life-history stages.

PubMed

Bruns, Emily; Carson, Martin; May, Georgiana

2012-08-02

Adaptation of pathogens to their hosts depends critically on factors affecting pathogen reproductive rate. While pathogen reproduction is the end result of an intricate interaction between host and pathogen, the relative contributions of host and pathogen genotype to variation in pathogen life history within the host are not well understood. Untangling these contributions allows us to identify traits with sufficient genetic variation for selection to act and to identify mechanisms of coevolution between pathogens and their hosts. We investigated the effects of pathogen and host genotype on three life-history components of pathogen fitness; infection efficiency, latent period, and sporulation capacity, in the oat crown rust fungus, Puccinia coronata f.sp. avenae, as it infects oats (Avena sativa). We show that both pathogen and host genotype significantly affect total spore production but do so through their effects on different life-history stages. Pathogen genotype has the strongest effect on the early stage of infection efficiency, while host genotype most strongly affects the later life-history stages of latent period and sporulation capacity. In addition, host genotype affected the relationship between pathogen density and the later life-history traits of latent period and sporulation capacity. We did not find evidence of pathogen-by-host genotypic (GxG) interactions. Our results illustrate mechanisms by which variation in host populations will affect the evolution of pathogen life history. Results show that different pathogen life-history stages have the potential to respond differently to selection by host or pathogen genotype and suggest mechanisms of antagonistic coevolution. Pathogen populations may adapt to host genotypes through increased infection efficiency while their plant hosts may adapt by limiting the later stages of pathogen growth and spore production within the host.

The Effect of Year-to-Year Rater Variation on IRT Linking

ERIC Educational Resources Information Center

Yen, Shu Jing; Ochieng, Charles; Michaels, Hillary; Friedman, Greg

2005-01-01

Year-to-year rater variation may result in constructed response (CR) parameter changes, making CR items inappropriate to use in anchor sets for linking or equating. This study demonstrates how rater severity affected the writing and reading scores. Rater adjustments were made to statewide results using an item response theory (IRT) methodology…

Exploiting temporal variability to understand tree recruitment response to climate change

Treesearch

Ines Ibanez; James S. Clark; Shannon LaDeau; Janneke Hill Ris Lambers

2007-01-01

Predicting vegetation shifts under climate change is a challenging endeavor, given the complex interactions between biotic and abiotic variables that influence demographic rates. To determine how current trends and variation in climate change affect seedling establishment, we analyzed demographic responses to spatiotemporal variation to temperature and soil moisture in...

Target Language Variation and Second-Language Acquisition: Learning English in New York City.

ERIC Educational Resources Information Center

Eisenstein, Miriam R.

1986-01-01

Investigates the role of dialect variation in the acquisition of American English by adult second language learners. The study revealed that dialect differences present problems for learners and cause variable intelligibility and negative learner attitude toward some varieties of English and its speakers. This attitude could negatively affect a…

Power and limitation of soil properties as predictors of variation in peak plant biomass in a northern mixed-grass prairie

USDA-ARS?s Scientific Manuscript database

Soil properties are thought to affect annual plant productivity in rangelands, and thus soil variables that are consistently correlated with variation in plant biomass may be general indicators of rangeland health. Here we measured several soil properties (e.g. aggregate stability, organic carbon, ...

Seasonal and elevational variation of δ18O and δ2H in the Willamette River basin

EPA Science Inventory

Climate change is expected to dramatically alter the timing and quantity of water within the nation’s river systems. These changes are driven by variation in the form, location and amount of precipitation that will affect the temporal and spatial distribution of river source wat...

Variation in Student Selection within the Australian Unified National System: A Case Study in Undergraduate Business Studies from Western Australia.

ERIC Educational Resources Information Center

Stanley, Gordon; Oliver, Jeff

1994-01-01

Data on admission criteria for four undergraduate business administration programs in Western Australian universities were used to investigate variation in student characteristics across schools. Results indicated large differences in student characteristics among schools, which could affect student progress and outcomes. Implications for such…

Variation in body mass of wild canvasback and redhead ducklings

USGS Publications Warehouse

Austin, Jane E.; Serie, Jerome R.

1994-01-01

We assessed variation in body mass of ducklings in single- and mixed-species broods of wild Canvasbacks (Aythya valisineria) and Redheads (Aythya americana) 20-50 days old. Body mass of canvasback ducklings was not affected by year and season (early vs. late hatch date) despite changes in water conditions. Mean body mass of male and female Canvasbacks did not differ in Class IIA but did differ in older age classes. Within-brood differences in body mass tended to be higher in Class IIA ducklings (6-7% of mean body mass for Canvasbacks, 9-11% in Redheads) and generally declined to 4-6% in Class IIC and older ducklings. Some within-brood differences were as high as 20-30% of mean body mass. Tests to assess sources of within-brood variation (age, sex, and season) in body mass for Canvasbacks were inconclusive. Variation within broods was generally less than that among broods for both Canvasbacks and Redheads. The lack of differences in duckling body mass between single- and mixed-species broods for any age class, sex, or species suggests that mass was not affected by interspecific brood parasitism.

Generality and cultural variation in the experience of regret.

PubMed

Breugelmans, Seger M; Zeelenberg, Marcel; Gilovich, Thomas; Huang, Wen-Hsien; Shani, Yaniv

2014-12-01

Regret is the prototypical decision-related emotion. Most theory and research on regret comes from the United States and Europe, but recent research has suggested potential cross-cultural differences in regret. We examined generality and cultural variation in the experience of regret. A cross-cultural study compared experiences of regret with those of disappointment and guilt as reported by participants from the United States (n = 143), the Netherlands (n = 147), Israel (n = 148), and Taiwan (n = 115). We found strong evidence for generality of the distinct emotion components of regret, compared with those of disappointment and guilt. We also found cultural variation in the frequency and intensity of regret in intrapersonal situations (regrets about outcomes affecting the self) and interpersonal regrets (regrets about outcomes affecting others). Whereas in the U.S. sample, regret was experienced more intensely in intrapersonal than interpersonal situations, both emotions were experienced more intensely in interpersonal situations in the Taiwanese sample.

Relevant principal factors affecting the reproducibility of insect primary culture.

PubMed

Ogata, Norichika; Iwabuchi, Kikuo

2017-06-01

The primary culture of insect cells often suffers from problems with poor reproducibility in the quality of the final cell preparations. The cellular composition of the explants (cell number and cell types), surgical methods (surgical duration and surgical isolation), and physiological and genetic differences between donors may be critical factors affecting the reproducibility of culture. However, little is known about where biological variation (interindividual differences between donors) ends and technical variation (variance in replication of culture conditions) begins. In this study, we cultured larval fat bodies from the Japanese rhinoceros beetle, Allomyrina dichotoma, and evaluated, using linear mixed models, the effect of interindividual variation between donors on the reproducibility of the culture. We also performed transcriptome analysis of the hemocyte-like cells mainly seen in the cultures using RNA sequencing and ultrastructural analyses of hemocytes using a transmission electron microscope, revealing that the cultured cells have many characteristics of insect hemocytes.

Influence of COMT genotype and affective distractors on the processing of self-generated thought.

PubMed

Kilford, Emma J; Dumontheil, Iroise; Wood, Nicholas W; Blakemore, Sarah-Jayne

2015-06-01

The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val(158)Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function. © The Author (2014). Published by Oxford University Press.

Effects of variables upon pyrotechnically induced shock response spectra

NASA Technical Reports Server (NTRS)

Smith, J. L.

1986-01-01

Throughout the aerospace industry, large variations of 50 percent (6 dB) or more are continually noted for linear shaped charge (LSC) generated shock response spectra (SRS) from flight data (from the exact same location on different flights) and from plate tests (side by side measurements on the same test). A research program was developed to investigate causes of these large SRS variations. A series of ball drop calibration tests to verify calibration of accelerometers and a series of plate tests to investigate charge and assembly variables were performed. The resulting data were analyzed to determine if and to what degree manufacturing and assembly variables, distance from the shock source, data acquisition instrumentation, and shock energy propagation affect the SRS. LSC variables consisted of coreload, standoff, and apex angle. The assembly variable was the torque on the LSC holder. Other variables were distance from source of accelerometers, accelerometer mounting methods, and joint effects. Results indicated that LSC variables did not affect SRS as long as the plate was severed. Accelerometers mounted on mounting blocks showed significantly lower levels above 5000 Hz. Lap joints did not affect SRS levels. The test plate was mounted in an almost free-free state; therefore, distance from the source did not affect the SRS. Several varieties and brands of accelerometers were used, and all but one demonstrated very large variations in SRS.

Environmental Effects on Affect: Density, Noise and Personality.

ERIC Educational Resources Information Center

Bharucha-Reid, Rodabe; Kivak, H. Asuman

1982-01-01

Research findings are reported of a study (N=88 undergraduate males) of molar crowding in urban centers which involved the simultaneous variation of social density, spatial density, noise, and personality as they effect room affect (physical and psychological). Several main effects proved significant. (Author/DC)

Bipolar disorders in the Arab world: a critical review.

PubMed

Kronfol, Ziad; Zakaria Khalil, Mostafa; Kumar, Pankaj; Suhre, Karsten; Karam, Elie; McInnis, Melvin

2015-05-01

Bipolar disorders are common psychiatric disorders that affect 1-5% of the population worldwide. Major advances in the epidemiology, pathophysiology, and treatment of the disorders have recently occurred. The majority of published reports, however, originate from the Western hemisphere, mostly Europe and the United States. There is a shortage of data from the Arab world on bipolar disorders. In an era of globalization and rapid communication, it is not clear to what extent research findings pertaining to one part of the world are by necessity applicable to other parts. Psychiatric disorders are known to be affected by the culture in which they occur, and knowledge of variations in illness presentation in different ethnic groups is also increasing. However, knowledge of variations affecting Arab populations remains quite limited. This paper provides a critical review of the literature on bipolar affective disorders in the Arab world, pointing to major gaps in knowledge and future opportunities to fill these gaps. © 2015 New York Academy of Sciences.

Hospital organizational factors affect the use of immediate breast reconstruction after mastectomy for breast cancer in the Netherlands.

PubMed

Schreuder, K; van Bommel, A C M; de Ligt, K M; Maduro, J H; Vrancken Peeters, M T F D; Mureau, M A M; Siesling, S

2017-08-01

Significant hospital variation in the use of immediate breast reconstruction (IBR) after mastectomy exists in the Netherlands. Aims of this study were to identify hospital organizational factors affecting the use of IBR after mastectomy for ductal carcinoma in situ (DCIS) or invasive breast cancer (BC) and to analyze whether these factors explain the variation. Patients with DCIS or primary invasive BC treated with mastectomy between 2011 and 2013 were selected from the national NABON Breast Cancer Audit. Hospital and organizational factors were collected with an online web-based survey. Regression analyses were performed to determine whether these factors accounted for the hospital variation. In total, 78% (n = 72) of all Dutch hospitals participated in the survey. In these hospitals 16,471 female patients underwent a mastectomy for DCIS (n = 1,980) or invasive BC (n = 14,491) between 2011 and 2014. IBR was performed in 41% of patients with DCIS (hospital range 0-80%) and in 17% of patients with invasive BC (hospital range 0-62%). Hospital type, number of plastic surgeons available and attendance of a plastic surgeon at the MDT meeting increased IBR rates. For invasive BC, higher percentage of mastectomies and more weekly MDT meetings also significantly increased IBR rates. Adjusted data demonstrated decreased IBR rates for DCIS (average 35%, hospital range 0-49%) and invasive BC (average 15%, hospital range 0-18%). Hospital organizational factors affect the use of IBR in the Netherlands. Although only partly explaining hospital variation, optimization of these factors could lead to less variation in IBR rates. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unit Level Variations And Peer Influences In Mental Health Diagnoses In The U.S. Army

DTIC Science & Technology

2017-12-01

INFLUENCES IN MENTAL HEALTH DIAGNOSES IN THE U.S. ARMY by Zhi Wen Tan Kian Wee Evwin Lee December 2017 Thesis Advisor: Yu-Chu Shen Co-Advisor...DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE UNIT-LEVEL VARIATIONS AND PEER INFLUENCES IN MENTAL HEALTH DIAGNOSES IN THE U.S. ARMY 5... health care system, to examine how unit-level variations in incidents of mental health diagnoses affect the likelihood of an individual developing

Plant Fertilization Interacts with Life History: Variation in Stoichiometry and Performance in Nettle-Feeding Butterflies

PubMed Central

Audusseau, Hélène; Kolb, Gundula; Janz, Niklas

2015-01-01

Variation in food stoichiometry affects individual performance and population dynamics, but it is also likely that species with different life histories should differ in their sensitivity to food stoichiometry. To address this question, we investigated the ability of the three nettle-feeding butterflies (Aglais urticae, Polygonia c-album, and Aglais io) to respond adaptively to induced variation in plant stoichiometry in terms of larval performance. We hypothesized that variation in larval performance between plant fertilization treatments should be functionally linked to species differences in host plant specificity. We found species-specific differences in larval performance between plant fertilization treatments that could not be explained by nutrient limitation. We showed a clear evidence of a positive correlation between food stoichiometry and development time to pupal stage and pupal mass in A. urticae. The other two species showed a more complex response. Our results partly supported our prediction that host plant specificity affects larval sensitivity to food stoichiometry. However, we suggest that most of the differences observed may instead be explained by differences in voltinism (number of generations per year). We believe that the potential of some species to respond adaptively to variation in plant nutrient content needs further attention in the face of increased eutrophication due to nutrient leakage from human activities. PMID:25932628

Plant fertilization interacts with life history: variation in stoichiometry and performance in nettle-feeding butterflies.

PubMed

Audusseau, Hélène; Kolb, Gundula; Janz, Niklas

2015-01-01

Variation in food stoichiometry affects individual performance and population dynamics, but it is also likely that species with different life histories should differ in their sensitivity to food stoichiometry. To address this question, we investigated the ability of the three nettle-feeding butterflies (Aglais urticae, Polygonia c-album, and Aglais io) to respond adaptively to induced variation in plant stoichiometry in terms of larval performance. We hypothesized that variation in larval performance between plant fertilization treatments should be functionally linked to species differences in host plant specificity. We found species-specific differences in larval performance between plant fertilization treatments that could not be explained by nutrient limitation. We showed a clear evidence of a positive correlation between food stoichiometry and development time to pupal stage and pupal mass in A. urticae. The other two species showed a more complex response. Our results partly supported our prediction that host plant specificity affects larval sensitivity to food stoichiometry. However, we suggest that most of the differences observed may instead be explained by differences in voltinism (number of generations per year). We believe that the potential of some species to respond adaptively to variation in plant nutrient content needs further attention in the face of increased eutrophication due to nutrient leakage from human activities.

Effects of resource variation during early life and adult social environment on contest outcomes in burying beetles: a context-dependent silver spoon strategy?

PubMed

Hopwood, Paul E; Moore, Allen J; Royle, Nick J

2014-06-22

Good early nutritional conditions may confer a lasting fitness advantage over individuals suffering poor early conditions (a 'silver spoon' effect). Alternatively, if early conditions predict the likely adult environment, adaptive plastic responses might maximize individual performance when developmental and adult conditions match (environmental-matching effect). Here, we test for silver spoon and environmental-matching effects by manipulating the early nutritional environment of Nicrophorus vespilloides burying beetles. We manipulated nutrition during two specific early developmental windows: the larval environment and the post-eclosion environment. We then tested contest success in relation to variation in adult social environmental quality experienced (defined according to whether contest opponents were smaller (good environment) or larger (poor environment) than the focal individual). Variation in the larval environment influenced adult body size but not contest success per se for a given adult social environment experienced (an 'indirect' silver spoon effect). Variation in post-eclosion environment affected contest success dependent on the quality of the adult environment experienced (a context-dependent 'direct' silver spoon effect). By contrast, there was no evidence for environmental-matching. The results demonstrate the importance of social environmental context in determining how variation in nutrition in early life affects success as an adult.

Spatial-Temporal Variations of Chlorophyll-a in the Adjacent Sea Area of the Yangtze River Estuary Influenced by Yangtze River Discharge.

PubMed

Wang, Ying; Jiang, Hong; Jin, Jiaxin; Zhang, Xiuying; Lu, Xuehe; Wang, Yueqi

2015-05-20

Carrying abundant nutrition, terrigenous freshwater has a great impact on the spatial and temporal heterogeneity of phytoplankton in coastal waters. The present study analyzed the spatial-temporal variations of Chlorophyll-a (Chl-a) concentration under the influence of discharge from the Yangtze River, based on remotely sensed Chl-a concentrations. The study area was initially zoned to quantitatively investigate the spatial variation patterns of Chl-a. Then, the temporal variation of Chl-a in each zone was simulated by a sinusoidal curve model. The results showed that in the inshore waters, the terrigenous discharge was the predominant driving force determining the pattern of Chl-a, which brings the risk of red tide disasters; while in the open sea areas, Chl-a was mainly affected by meteorological factors. Furthermore, a diversity of spatial and temporal variations of Chl-a existed based on the degree of influences from discharge. The diluted water extended from inshore to the east of Jeju Island. This process affected the Chl-a concentration flowing through the area, and had a potential impact on the marine environment. The Chl-a from September to November showed an obvious response to the discharge from July to September with a lag of 1 to 2 months.

Spatial-Temporal Variations of Chlorophyll-a in the Adjacent Sea Area of the Yangtze River Estuary Influenced by Yangtze River Discharge

PubMed Central

Wang, Ying; Jiang, Hong; Jin, Jiaxin; Zhang, Xiuying; Lu, Xuehe; Wang, Yueqi

2015-01-01

Carrying abundant nutrition, terrigenous freshwater has a great impact on the spatial and temporal heterogeneity of phytoplankton in coastal waters. The present study analyzed the spatial-temporal variations of Chlorophyll-a (Chl-a) concentration under the influence of discharge from the Yangtze River, based on remotely sensed Chl-a concentrations. The study area was initially zoned to quantitatively investigate the spatial variation patterns of Chl-a. Then, the temporal variation of Chl-a in each zone was simulated by a sinusoidal curve model. The results showed that in the inshore waters, the terrigenous discharge was the predominant driving force determining the pattern of Chl-a, which brings the risk of red tide disasters; while in the open sea areas, Chl-a was mainly affected by meteorological factors. Furthermore, a diversity of spatial and temporal variations of Chl-a existed based on the degree of influences from discharge. The diluted water extended from inshore to the east of Jeju Island. This process affected the Chl-a concentration flowing through the area, and had a potential impact on the marine environment. The Chl-a from September to November showed an obvious response to the discharge from July to September with a lag of 1 to 2 months. PMID:26006121

Regulatory Focus Affects Physician Risk Tolerance

PubMed Central

Veazie, Peter J.; McIntosh, Scott; Chapman, Benjamin P.; Dolan, James G.

2014-01-01

Risk tolerance is a source of variation in physician decision-making. This variation, if independent of clinical concerns, can result in mistaken utilization of health services. To address such problems, it will be helpful to identify nonclinical factors of risk tolerance, particularly those amendable to intervention – regulatory focus theory suggests such a factor. This study tested whether regulatory focus affects risk tolerance among primary care physicians. Twenty-seven primary care physicians were assigned to promotion-focused or prevention-focused manipulations and compared on the Risk Taking Attitudes in Medical Decision Making scale using a randomization test. Results provide evidence that physicians assigned to the promotion-focus manipulation adopted an attitude of greater risk tolerance than the physicians assigned to the prevention-focused manipulation (P=0.01). The Cohen’s d statistic was conventionally large at 0.92. Results imply that situational regulatory focus in primary care physicians affects risk tolerance and may thereby be a nonclinical source of practice variation. Results also provide marginal evidence that chronic regulatory focus is associated with risk tolerance (P=0.05), but the mechanism remains unclear. Research and intervention targeting physician risk tolerance may benefit by considering situational regulatory focus as an explanatory factor. PMID:25431799

Case Presentations Demonstrating Periodontal Treatment Variation: PEARL Network.

PubMed

Curro, Frederick A; Grill, Ashley C; Matthews, Abigail G; Martin, John; Kalenderian, Elisabeth; Craig, Ronald G; Naftolin, Frederick; Thompson, Van P

2015-06-01

Variation in periodontal terminology can affect the diagnosis and treatment plan as assessed by practicing general dentists in the Practitioners Engaged in Applied Research and Learning (PEARL) Network. General dentists participating in the PEARL Network are highly screened, credentialed, and qualified and may not be representative of the general population of dentists. Ten randomized case presentations ranging from periodontal health to gingivitis, to mild, moderate, and severe periodontitis were randomly presented to respondents. Descriptive comparisons were made between these diagnosis groups in terms of the treatment recommendations following diagnosis. PEARL practitioners assessing periodontal clinical scenarios were found to either over- or under-diagnose the case presentations, which affected treatment planning, while the remaining responses concurred with respect to the diagnosis. The predominant diagnosis was compared with that assigned by two practicing periodontists. There was variation in treatment based on the diagnosis for gingivitis and the lesser forms of periodontitis. Data suggests that a lack of clarity of periodontal terminology affects both diagnosis and treatment planning, and terminology may be improved by having diagnosis codes, which could be used to assess treatment outcomes. This article provides data to support best practice for the use of diagnosis coding and integration of dentistry with medicine using ICD-10 terminology.

Chemical and Conformational Diversity of Modified Nucleosides Affects tRNA Structure and Function.

PubMed

Väre, Ville Y P; Eruysal, Emily R; Narendran, Amithi; Sarachan, Kathryn L; Agris, Paul F

2017-03-16

RNAs are central to all gene expression through the control of protein synthesis. Four major nucleosides, adenosine, guanosine, cytidine and uridine, compose RNAs and provide sequence variation, but are limited in contributions to structural variation as well as distinct chemical properties. The ability of RNAs to play multiple roles in cellular metabolism is made possible by extensive variation in length, conformational dynamics, and the over 100 post-transcriptional modifications. There are several reviews of the biochemical pathways leading to RNA modification, but the physicochemical nature of modified nucleosides and how they facilitate RNA function is of keen interest, particularly with regard to the contributions of modified nucleosides. Transfer RNAs (tRNAs) are the most extensively modified RNAs. The diversity of modifications provide versatility to the chemical and structural environments. The added chemistry, conformation and dynamics of modified nucleosides occurring at the termini of stems in tRNA's cloverleaf secondary structure affect the global three-dimensional conformation, produce unique recognition determinants for macromolecules to recognize tRNAs, and affect the accurate and efficient decoding ability of tRNAs. This review will discuss the impact of specific chemical moieties on the structure, stability, electrochemical properties, and function of tRNAs.

Evolutionary genetics of maternal effects

PubMed Central

Wolf, Jason B.; Wade, Michael J.

2016-01-01

Maternal genetic effects (MGEs), where genes expressed by mothers affect the phenotype of their offspring, are important sources of phenotypic diversity in a myriad of organisms. We use a single‐locus model to examine how MGEs contribute patterns of heritable and nonheritable variation and influence evolutionary dynamics in randomly mating and inbreeding populations. We elucidate the influence of MGEs by examining the offspring genotype‐phenotype relationship, which determines how MGEs affect evolutionary dynamics in response to selection on offspring phenotypes. This approach reveals important results that are not apparent from classic quantitative genetic treatments of MGEs. We show that additive and dominance MGEs make different contributions to evolutionary dynamics and patterns of variation, which are differentially affected by inbreeding. Dominance MGEs make the offspring genotype‐phenotype relationship frequency dependent, resulting in the appearance of negative frequency‐dependent selection, while additive MGEs contribute a component of parent‐of‐origin dependent variation. Inbreeding amplifies the contribution of MGEs to the additive genetic variance and, therefore enhances their evolutionary response. Considering evolutionary dynamics of allele frequency change on an adaptive landscape, we show that this landscape differs from the mean fitness surface, and therefore, under some condition, fitness peaks can exist but not be “available” to the evolving population. PMID:26969266

Flower-level developmental plasticity to nutrient availability in Datura stramonium: implications for the mating system.

PubMed

Camargo, Iván Darío; Nattero, Julieta; Careaga, Sonia A; Núñez-Farfán, Juan

2017-10-17

Studies of phenotypic plasticity in plants have mainly focused on (1) the effect of environmental variation on whole-plant traits related to the number of modules rather than on (2) the phenotypic consequences of environmental variation in traits of individual modules. Since environmental and developmental factors can produce changes in traits related to the mating system, this study used the second approach to investigate whether within-individual variation in herkogamy-related traits is affected by the environment during plant development in two populations of Datura stramonium , an annual herb with a hypothesized persistent mixed mating system, and to determine which morphological traits may promote self-fertilization. Full-sib families of two Mexican populations of D. stramonium , with contrasting ecological histories, were grown under low, mid and high nutrient availability to investigate the effects of genetic, environmental and within-plant flower position on flower size, corolla, stamen and pistil lengths, and herkogamy. Populations showed differences in familial variation, plasticity and familial differences in plasticity in most floral traits analysed. In one population (Ticumán), the effect of flower position on trait variation varied among families, whereas in the other (Pedregal) the effect of flower position interacted with the nutrient environment. Flower size varied with the position of flowers, but in the opposite direction between populations in low nutrients; a systematic within-plant trend of reduction in flower size, pistil length and herkogamy with flower position increased the probability of self-fertilization in the Pedregal population. Besides genetic variation in floral traits between and within populations, environmental variation affects phenotypic floral trait values at the whole-plant level, as well as among flower positions. The interaction between flower position and nutrient environment can affect the plant's mating system, and this differs between populations. Thus, reductions in herkogamy with flower positions may be expected in environments with either low pollinator abundance or low nutrients. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

The Role of Individual Traits and Environmental Factors for Diet Composition of Sheep

PubMed Central

Mysterud, Atle; Austrheim, Gunnar

2016-01-01

Large herbivore consumption of forage is known to affect vegetation composition and thereby ecosystem functions. It is thus important to understand how diet composition arises as a mixture of individual variation in preferences and environmental drivers of availability, but few studies have quantified both. Based on 10 years of data on diet composition by aid of microhistological analysis for sheep kept at high and low population density, we analysed how both individual traits (sex, age, body mass, litter size) linked to preference and environmental variation (density, climate proxies) linked to forage availability affected proportional intake of herbs (high quality/low availability) and Avenella flexuosa (lower quality/high availability). Environmental factors affecting current forage availability such as population density and seasonal and annual variation in diet had the most marked impact on diet composition. Previous environment of sheep (switch between high and low population density) had no impact on diet, suggesting a comparably minor role of learning for density dependent diet selection. For individual traits, only the difference between lambs and ewes affected proportion of A. flexuosa, while body mass better predicted proportion of herbs in diet. Neither sex, body mass, litter size, ewe age nor mass of ewe affected diet composition of lambs, and there was no effect of age, body mass or litter size on diet composition of ewes. Our study highlights that diet composition arises from a combination of preferences being predicted by lamb and ewes’ age and/or body mass differences, and the immediate environment in terms of population density and proxies for vegetation development. PMID:26731411

Stress hormones in relation to breeding status and territory location in colonial king penguin: a role for social density?

PubMed

Viblanc, Vincent A; Gineste, Benoit; Stier, Antoine; Robin, Jean-Patrice; Groscolas, René

2014-07-01

Because glucocorticoid (stress) hormones fundamentally affect various aspects of the behaviour, life history and fitness of free-living vertebrates, there is a need to understand the environmental factors shaping their variation in natural populations. Here, we examined whether spatial heterogeneity in breeding territory quality affected the stress of colonial king penguin (Aptenodytes patagonicus). We assessed the effects of local climate (wind, sun and ambient temperature) and social conditions (number of neighbours, distance to neighbours) on the baseline levels of plasma total corticosterone (CORT) in 77 incubating and 42 chick-brooding birds, breeding on territories of central or peripheral colony location. We also assessed the oxidative stress status of a sub-sample of central vs. peripheral chick-brooders to determine whether chronic stress arose from breeding on specific territories. On average, we found that brooders had 55% higher CORT levels than incubators. Regardless of breeding status, central birds experienced greater social density (higher number of neighbours, shorter distance between territories) and had higher CORT levels than peripheral birds. Increasing social density positively explained 40% of the variation in CORT levels of both incubators and brooders, but the effect was more pronounced in brooders. In contrast, climate was similar among breeding territories and did not significantly affect the CORT levels of breeding birds. In brooders, oxidative stress status was not affected by local density or weather conditions. These results highlight that local heterogeneity in breeding (including social) conditions may strongly affect the stress levels of breeding seabirds. The fitness consequences of such variation remain to be investigated.

Relationship between workplace spirituality and organizational citizenship behavior among nurses through mediation of affective organizational commitment.

PubMed

Kazemipour, Farahnaz; Mohamad Amin, Salmiah; Pourseidi, Bahram

2012-09-01

This study aims to investigate the relationships between workplace spirituality, organizational citizenship behavior (OCB), and affective organizational commitment among nurses, and whether affective commitment mediates the relationship between workplace spirituality and OCB. In the present correlational study, a cross-sectional design was employed, and data were collected using a questionnaire-based survey. Based on the random sampling, 305 nurses were chosen and questionnaires were distributed among respondents in four public and general hospitals located in Kerman, Iran. To analyze the data descriptive statistics, Pearson coefficient, simple and multiple regression, and path analyses were also conducted. Workplace spirituality has a positive influence on nurses' OCB and affective commitment. Workplace spirituality explained 16% of the variation in OCB, while it explained 35% of the variation in affective commitment among nurses. Moreover, affective organizational commitment mediated the impact of workplace spirituality on OCB. Workplace spirituality predicts nurses' OCB and affective organizational commitment. It emphasizes benefits from the new perspective of workplace spirituality, particularly among nurses who need to be motivated in their work. This study illustrates that there are potential benefits owing to the positive influence of workplace spirituality on OCB and affective commitment among nurses. Managers of nursing services should consider workplace spirituality and its positive influence on nurses' outcomes in order to improve their performance and, subsequently, the healthcare system. © 2012 Sigma Theta Tau International.

Variation in carbon isotope discrimination within and among Sphagnum species in a temperate wetland.

PubMed

Rice, S K

2000-04-01

Field samples of bryophytes are highly variable in carbon isotope discrimination values (Δ, a measure of 13 CO 2 uptake relative to 12 CO 2 ), but it is unknown what affects Δ under field conditions, or how variation in Δ relates to bryophyte performance. This study employed field and greenhouse common garden studies to evaluate the influence of microsite, seasonal, and genetic variation on Δ in peatmosses. Three species of Sphagnum that occupy hollow (S. recurvum), carpet (S. palustre), and hummock (S. tenerum) habitats were sampled for relative growth rates (RGR), C:N ratio, and Δ throughout a growing season. Values of Δ ranged from 19.0 to 27.1‰. This variation was unrelated to species (P=0.61). However, Δ varied seasonally (P<0.001), with lower discrimination in the spring (mean 22.5‰), followed by summer (23.8‰) and winter (24.7‰). There was also significant microsite variation (P=0.015) which disappeared when plants were grown in a common garden. In both spring and summer, microsite variation in Δ was inversely related to RGR (P<0.001), but unrelated to C:N ratios (P>0.08). These results suggest that environmental, not genetic, variation at microsites affects Δ in non-vascular plants. However, environmental control of Δ is unlike that in vascular plants where water limitation lowers chloroplastic demand and increases resistance to carbon uptake. In non-vascular plants, water limitation lowers chloroplastic demand and decreases resistance to carbon uptake. These processes have additive effects and generate high spatial and seasonal variability in Δ.

Effect of soil moisture on seasonal variation in indoor radon concentration: modelling and measurements in 326 Finnish houses

PubMed Central

Arvela, H.; Holmgren, O.; Hänninen, P.

2016-01-01

The effect of soil moisture on seasonal variation in soil air and indoor radon is studied. A brief review of the theory of the effect of soil moisture on soil air radon has been presented. The theoretical estimates, together with soil moisture measurements over a period of 10 y, indicate that variation in soil moisture evidently is an important factor affecting the seasonal variation in soil air radon concentration. Partitioning of radon gas between the water and air fractions of soil pores is the main factor increasing soil air radon concentration. On two example test sites, the relative standard deviation of the calculated monthly average soil air radon concentration was 17 and 26 %. Increased soil moisture in autumn and spring, after the snowmelt, increases soil gas radon concentrations by 10–20 %. In February and March, the soil gas radon concentration is in its minimum. Soil temperature is also an important factor. High soil temperature in summer increased the calculated soil gas radon concentration by 14 %, compared with winter values. The monthly indoor radon measurements over period of 1 y in 326 Finnish houses are presented and compared with the modelling results. The model takes into account radon entry, climate and air exchange. The measured radon concentrations in autumn and spring were higher than expected and it can be explained by the seasonal variation in the soil moisture. The variation in soil moisture is a potential factor affecting markedly to the high year-to-year variation in the annual or seasonal average radon concentrations, observed in many radon studies. PMID:25899611

Does thinning affect gypsy moth dynamics?

Treesearch

Andrew M. Liebhold; Rose-Marie Muzika; Kurt W. Gottschalk

1998-01-01

In northeastern U.S. forests there is considerable variation in susceptibility (defoliation potential) and vulnerability (tree mortality) to gypsy moth (Lymantria dispar [L.]). Thinning has been suggested as a way to reduce susceptibility and/or vulnerability. We evaluated how thinning affected the dynamics of gypsy moth populations by experimentally...

Computational Analyses of Synergism in Small Molecular Network Motifs

PubMed Central

Zhang, Yili; Smolen, Paul; Baxter, Douglas A.; Byrne, John H.

2014-01-01

Cellular functions and responses to stimuli are controlled by complex regulatory networks that comprise a large diversity of molecular components and their interactions. However, achieving an intuitive understanding of the dynamical properties and responses to stimuli of these networks is hampered by their large scale and complexity. To address this issue, analyses of regulatory networks often focus on reduced models that depict distinct, reoccurring connectivity patterns referred to as motifs. Previous modeling studies have begun to characterize the dynamics of small motifs, and to describe ways in which variations in parameters affect their responses to stimuli. The present study investigates how variations in pairs of parameters affect responses in a series of ten common network motifs, identifying concurrent variations that act synergistically (or antagonistically) to alter the responses of the motifs to stimuli. Synergism (or antagonism) was quantified using degrees of nonlinear blending and additive synergism. Simulations identified concurrent variations that maximized synergism, and examined the ways in which it was affected by stimulus protocols and the architecture of a motif. Only a subset of architectures exhibited synergism following paired changes in parameters. The approach was then applied to a model describing interlocked feedback loops governing the synthesis of the CREB1 and CREB2 transcription factors. The effects of motifs on synergism for this biologically realistic model were consistent with those for the abstract models of single motifs. These results have implications for the rational design of combination drug therapies with the potential for synergistic interactions. PMID:24651495

Precipitation drives interannual variation in summer soil respiration in a Mediterranean-climate, mixed-conifer forest

Treesearch

M. Concilio; J. Chen; S. Ma; M. North

2009-01-01

Predictions of future climate change rely on models of how both environmental conditions and disturbance impact carbon cycling at various temporal and spatial scales. Few multi-year studies, however, have examined how carbon efflux is affected by the interaction of disturbance and interannual climate variation. We measured daytime soil respiration (R...