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Sample records for natural selection animal

  1. Animal genetic resources in Brazil: result of five centuries of natural selection.

    PubMed

    Mariante, A da S; Egito, A A

    2002-01-01

    Brazil has various species of domestic animals, which developed from breeds brought by the Portuguese settlers soon after their discovery. For five centuries, these breeds have been subjected to natural selection in specific environments. Today, they present characteristics adapted to the specific Brazilian environmental conditions. These breeds developed in Brazil are known as "Crioulo," "local," or naturalized. From the beginning of the 20th century, some exotic breeds, selected in temperate regions, have begun to be imported. Although more productive, these breeds do not have adaptive traits, such as resistance to disease and parasites found in breeds considered to be "native." Even so, little by little, they replaced the native breeds, to such an extent that the latter are in danger of extinction. In 1983, to avoid the loss of this important genetic material, the National Research Center for Genetic Resources and Biotechnology (Cenargen) of the Brazilian Agricultural Research Corporation (Embrapa) decided to include conservation of animal genetic resources in its research program Conservation and Utilization of Genetic Resources. Until this time, they were only concerned with conservation of native plants. Conservation has been carried out by various research centers of Embrapa, universities, state research corporations, and private farmers, with a single coordinator at the national level, Cenargen. Specifically, conservation is being carried out by conservation nuclei, which are specific herds in which the animals are being conserved, situated in the habitats where the animals have been subjected to natural selection. This involves storage of semen and embryos from cattle, horses, buffaloes, donkeys, goats, sheep, and pigs. The Brazilian Animal Germplasm Bank is kept at Cenargen, which is responsible for the storage of semen and embryos of various breeds of domestic animals threatened with extinction, where almost 45,000 doses of semen and more than 200

  2. Selection signature in domesticated animals.

    PubMed

    Zhangyuan, Pan; Xiaoyun, He; Xiangyu, Wang; Xiaofei, Guo; Xiaohan, Cao; Wenping, Hu; Ran, Di; Qiuyue, Liu; Mingxing, Chu

    2016-12-20

    Domesticated animals play an important role in the life of humanity. All these domesticated animals undergo same process, first domesticated from wild animals, then after long time natural and artificial selection, formed various breeds that adapted to the local environment and human needs. In this process, domestication, natural and artificial selection will leave the selection signal in the genome. The research on these selection signals can find functional genes directly, is one of the most important strategies in screening functional genes. The current studies of selection signal have been performed in pigs, chickens, cattle, sheep, goats, dogs and other domestic animals, and found a great deal of functional genes. This paper provided an overview of the types and the detected methods of selection signal, and outlined researches of selection signal in domestic animals, and discussed the key issues in selection signal analysis and its prospects.

  3. Demonstrating Natural Selection

    ERIC Educational Resources Information Center

    Hinds, David S.; Amundson, John C.

    1975-01-01

    Describes laboratory exercises with chickens selecting their food from dyed and natural corn kernels as a method of demonstrating natural selection. The procedure is based on the fact that organisms that blend into their surroundings escape predation. (BR)

  4. Demonstrating Natural Selection

    ERIC Educational Resources Information Center

    Hinds, David S.; Amundson, John C.

    1975-01-01

    Describes laboratory exercises with chickens selecting their food from dyed and natural corn kernels as a method of demonstrating natural selection. The procedure is based on the fact that organisms that blend into their surroundings escape predation. (BR)

  5. Sexual selection and animal personality.

    PubMed

    Schuett, Wiebke; Tregenza, Tom; Dall, Sasha R X

    2010-05-01

    Consistent individual behavioural tendencies, termed "personalities", have been identified in a wide range of animals. Functional explanations for personality have been proposed, but as yet, very little consideration has been given to a possible role for sexual selection in maintaining differences in personality and its stability within individuals. We provide an overview of the available literature on the role of personality traits in intrasexual competition and mate choice in both human and non-human animals and integrate this into a framework for considering how sexual selection can generate and maintain personality. For this, we consider the evolution and maintenance of both main aspects of animal personality: inter-individual variation and intra-individual consistency.

  6. Reinventing Natural Selection

    ERIC Educational Resources Information Center

    Geraedts, Caspar L.; Boersma, Kerst Th.

    2006-01-01

    Although many research studies report students' Lamarckian misconceptions, only a few studies present learning and teaching strategies that focus on the successful development of the concept of natural selection. The learning and teaching strategy for upper secondary students (aged 15-16) presented in this study conducted in The Netherlands is…

  7. Gaia and natural selection

    NASA Astrophysics Data System (ADS)

    Lenton, Timothy M.

    1998-07-01

    Evidence indicates that the Earth self-regulates at a state that is tolerated by life, but why should the organisms that leave the most descendants be the ones that contribute to regulating their planetary environment? The evolving Gaia theory focuses on the feedback mechanisms, stemming from naturally selected traits of organisms, that could generate such self-regulation.

  8. Selective attention, working memory, and animal intelligence.

    PubMed

    Matzel, Louis D; Kolata, Stefan

    2010-01-01

    Accumulating evidence indicates that the storage and processing capabilities of the human working memory system co-vary with individuals' performance on a wide range of cognitive tasks. The ubiquitous nature of this relationship suggests that variations in these processes may underlie individual differences in intelligence. Here we briefly review relevant data which supports this view. Furthermore, we emphasize an emerging literature describing a trait in genetically heterogeneous mice that is quantitatively and qualitatively analogous to general intelligence (g) in humans. As in humans, this animal analog of g co-varies with individual differences in both storage and processing components of the working memory system. Absent some of the complications associated with work with human subjects (e.g., phonological processing), this work with laboratory animals has provided an opportunity to assess otherwise intractable hypotheses. For instance, it has been possible in animals to manipulate individual aspects of the working memory system (e.g., selective attention), and to observe causal relationships between these variables and the expression of general cognitive abilities. This work with laboratory animals has coincided with human imaging studies (briefly reviewed here) which suggest that common brain structures (e.g., prefrontal cortex) mediate the efficacy of selective attention and the performance of individuals on intelligence test batteries. In total, this evidence suggests an evolutionary conservation of the processes that co-vary with and/or regulate "intelligence" and provides a framework for promoting these abilities in both young and old animals.

  9. Naturally selecting solutions

    PubMed Central

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems. PMID:23222169

  10. Naturalness and the genetic modification of animals.

    PubMed

    Verhoog, Henk

    2003-07-01

    In the past few years it has been recognised that so-called intrinsic concerns about genetic modification (GM) of plants and animals, for food in particular, have an important role in the public perception of GM. One of these concerns is the view that GM is 'unnatural'. This article gives an overview of the often conflicting views on the argument of unnaturalness in books and reports. The author gives a new direction to this discussion, by contrasting the common sense view of nature and animals, with the scientific concept of nature and what is natural. The view of nature and what is natural is always normative. This is illustrated by making explicit the concept of nature in organic farming, which explains why GM is rejected.

  11. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  12. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  13. A Natural Selection Game.

    ERIC Educational Resources Information Center

    Tashiro, Mark E.

    1984-01-01

    Provides rules for a game which simulates selection pressures on a hominid group. Objectives include an appreciation of how selectivity works, an understanding of how abiotic factors are able to influence a population, and how interactions within the population can influence the group. (JM)

  14. A Natural Selection Game.

    ERIC Educational Resources Information Center

    Tashiro, Mark E.

    1984-01-01

    Provides rules for a game which simulates selection pressures on a hominid group. Objectives include an appreciation of how selectivity works, an understanding of how abiotic factors are able to influence a population, and how interactions within the population can influence the group. (JM)

  15. Natural selection maximizes Fisher information.

    PubMed

    Frank, S A

    2009-02-01

    In biology, information flows from the environment to the genome by the process of natural selection. However, it has not been clear precisely what sort of information metric properly describes natural selection. Here, I show that Fisher information arises as the intrinsic metric of natural selection and evolutionary dynamics. Maximizing the amount of Fisher information about the environment captured by the population leads to Fisher's fundamental theorem of natural selection, the most profound statement about how natural selection influences evolutionary dynamics. I also show a relation between Fisher information and Shannon information (entropy) that may help to unify the correspondence between information and dynamics. Finally, I discuss possible connections between the fundamental role of Fisher information in statistics, biology and other fields of science.

  16. Traces of natural radionuclides in animal food

    NASA Astrophysics Data System (ADS)

    Merli, Isabella Desan; da Silveira, Marcilei A. Guazzelli; Medina, Nilberto H.

    2014-11-01

    Naturally occurring radioactive materials are present everywhere, e.g., in soil, air, housing materials, food, etc. Therefore, human beings and animals receive internal exposure from radioactive elements inside their bodies through breathing and alimentation. Gamma radiation has enough energy to remove an electron from the atom and compromise the rearrangement of electrons in the search for a more stable configuration which can disturb molecule chemical bonding. Food ingestion is one of the most common forms of radioisotopes absorption. The goal of this work is the measurement of natural gamma radiation rates from natural radioisotopes present in animal food. To determine the concentration of natural radionuclides present in animal food gamma-ray spectrometry was applied. We have prepared animal food samples for poultry, fish, dogs, cats and cattle. The two highest total ingestion effective doses observed refers to a sample of mineral salt cattle, 95.3(15) μSv/year, rabbit chow, with a value of 48(5) μSv/year, and cattle mineral salt, with a value of 69(7) μSv/year, while the annual total dose value from terrestrial intake radionuclide is of the order of 290 μSv/year.

  17. Traces of natural radionuclides in animal food

    SciTech Connect

    Merli, Isabella Desan; Guazzelli da Silveira, Marcilei A.; Medina, Nilberto H.

    2014-11-11

    Naturally occurring radioactive materials are present everywhere, e.g., in soil, air, housing materials, food, etc. Therefore, human beings and animals receive internal exposure from radioactive elements inside their bodies through breathing and alimentation. Gamma radiation has enough energy to remove an electron from the atom and compromise the rearrangement of electrons in the search for a more stable configuration which can disturb molecule chemical bonding. Food ingestion is one of the most common forms of radioisotopes absorption. The goal of this work is the measurement of natural gamma radiation rates from natural radioisotopes present in animal food. To determine the concentration of natural radionuclides present in animal food gamma-ray spectrometry was applied. We have prepared animal food samples for poultry, fish, dogs, cats and cattle. The two highest total ingestion effective doses observed refers to a sample of mineral salt cattle, 95.3(15) μSv/year, rabbit chow, with a value of 48(5) μSv/year, and cattle mineral salt, with a value of 69(7) μSv/year, while the annual total dose value from terrestrial intake radionuclide is of the order of 290 μSv/year.

  18. Genomic selection in animal breeding programs.

    PubMed

    van der Werf, Julius

    2013-01-01

    Genomic selection can have a major impact on animal breeding programs, especially where traits that are important in the breeding objective are hard to select for otherwise. Genomic selection provides more accurate estimates for breeding value earlier in the life of breeding animals, giving more selection accuracy and allowing lower generation intervals. From sheep to dairy cattle, the rates of genetic improvement could increase from 20 to 100 % and hard-to-measure traits can be improved more effectively.Reference populations for genomic selection need to be large, with thousands of animals measured for phenotype and genotype. The smaller the effective size of the breeding population, the larger the DNA segments they potentially share and the more accurate genomic prediction will be. The relative contribution of information from relatives in the reference population will be larger if the baseline accuracy is low, but such information is limited to closely related individuals and does not last over generations.

  19. Friendship and natural selection.

    PubMed

    Christakis, Nicholas A; Fowler, James H

    2014-07-22

    More than any other species, humans form social ties to individuals who are neither kin nor mates, and these ties tend to be with similar people. Here, we show that this similarity extends to genotypes. Across the whole genome, friends' genotypes at the single nucleotide polymorphism level tend to be positively correlated (homophilic). In fact, the increase in similarity relative to strangers is at the level of fourth cousins. However, certain genotypes are also negatively correlated (heterophilic) in friends. And the degree of correlation in genotypes can be used to create a "friendship score" that predicts the existence of friendship ties in a hold-out sample. A focused gene-set analysis indicates that some of the overall correlation in genotypes can be explained by specific systems; for example, an olfactory gene set is homophilic and an immune system gene set is heterophilic, suggesting that these systems may play a role in the formation or maintenance of friendship ties. Friends may be a kind of "functional kin." Finally, homophilic genotypes exhibit significantly higher measures of positive selection, suggesting that, on average, they may yield a synergistic fitness advantage that has been helping to drive recent human evolution.

  20. Precipitation drives global variation in natural selection.

    PubMed

    Siepielski, Adam M; Morrissey, Michael B; Buoro, Mathieu; Carlson, Stephanie M; Caruso, Christina M; Clegg, Sonya M; Coulson, Tim; DiBattista, Joseph; Gotanda, Kiyoko M; Francis, Clinton D; Hereford, Joe; Kingsolver, Joel G; Augustine, Kate E; Kruuk, Loeske E B; Martin, Ryan A; Sheldon, Ben C; Sletvold, Nina; Svensson, Erik I; Wade, Michael J; MacColl, Andrew D C

    2017-03-03

    Climate change has the potential to affect the ecology and evolution of every species on Earth. Although the ecological consequences of climate change are increasingly well documented, the effects of climate on the key evolutionary process driving adaptation-natural selection-are largely unknown. We report that aspects of precipitation and potential evapotranspiration, along with the North Atlantic Oscillation, predicted variation in selection across plant and animal populations throughout many terrestrial biomes, whereas temperature explained little variation. By showing that selection was influenced by climate variation, our results indicate that climate change may cause widespread alterations in selection regimes, potentially shifting evolutionary trajectories at a global scale.

  1. A quantum of natural selection

    NASA Astrophysics Data System (ADS)

    Lloyd, Seth

    2009-03-01

    The modern evolutionary synthesis, which marries Darwin's theory of natural selection with Mendel's genetics, was developed around the same time as quantum mechanics. Is there any connection between the two?

  2. Natural selection promotes antigenic evolvability.

    PubMed

    Graves, Christopher J; Ros, Vera I D; Stevenson, Brian; Sniegowski, Paul D; Brisson, Dustin

    2013-01-01

    The hypothesis that evolvability - the capacity to evolve by natural selection - is itself the object of natural selection is highly intriguing but remains controversial due in large part to a paucity of direct experimental evidence. The antigenic variation mechanisms of microbial pathogens provide an experimentally tractable system to test whether natural selection has favored mechanisms that increase evolvability. Many antigenic variation systems consist of paralogous unexpressed 'cassettes' that recombine into an expression site to rapidly alter the expressed protein. Importantly, the magnitude of antigenic change is a function of the genetic diversity among the unexpressed cassettes. Thus, evidence that selection favors among-cassette diversity is direct evidence that natural selection promotes antigenic evolvability. We used the Lyme disease bacterium, Borrelia burgdorferi, as a model to test the prediction that natural selection favors amino acid diversity among unexpressed vls cassettes and thereby promotes evolvability in a primary surface antigen, VlsE. The hypothesis that diversity among vls cassettes is favored by natural selection was supported in each B. burgdorferi strain analyzed using both classical (dN/dS ratios) and Bayesian population genetic analyses of genetic sequence data. This hypothesis was also supported by the conservation of highly mutable tandem-repeat structures across B. burgdorferi strains despite a near complete absence of sequence conservation. Diversification among vls cassettes due to natural selection and mutable repeat structures promotes long-term antigenic evolvability of VlsE. These findings provide a direct demonstration that molecular mechanisms that enhance evolvability of surface antigens are an evolutionary adaptation. The molecular evolutionary processes identified here can serve as a model for the evolution of antigenic evolvability in many pathogens which utilize similar strategies to establish chronic infections.

  3. Animal clocks: when science meets nature.

    PubMed

    Kronfeld-Schor, Noga; Bloch, Guy; Schwartz, William J

    2013-08-22

    Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian 'clock'), with the alternation of environmental light and darkness synchronizing (entraining) these rhythms to the natural day-night cycle. Our knowledge of the circadian system of animals at the molecular, cellular, tissue and organismal levels is remarkable, and we are beginning to understand how each of these levels contributes to the emergent properties and increased complexity of the system as a whole. For the most part, these analyses have been carried out using model organisms in standard laboratory housing, but to begin to understand the adaptive significance of the clock, we must expand our scope to study diverse animal species from different taxonomic groups, showing diverse activity patterns, in their natural environments. The seven papers in this Special Feature of Proceedings of the Royal Society B take on this challenge, reviewing the influences of moonlight, latitudinal clines, evolutionary history, social interactions, specialized temporal niches, annual variation and recently appreciated post-transcriptional molecular mechanisms. The papers emphasize that the complexity and diversity of the natural world represent a powerful experimental resource.

  4. Natural selection and population dynamics.

    PubMed

    Saccheri, Ilik; Hanski, Ilkka

    2006-06-01

    To what extent, and under which circumstances, are population dynamics influenced by concurrent natural selection? Density dependence and environmental stochasticity are generally expected to subsume any selective modulation of population growth rate, but theoretical considerations point to conditions under which selection can have an appreciable impact on population dynamics. By contrast, empirical research has barely scratched the surface of this fundamental question in population biology. Here, we present a diverse body of mostly empirical evidence that demonstrates how selection can influence population dynamics, including studies of small populations, metapopulations, cyclical populations and host-pathogen interactions. We also discuss the utility, in this context, of inferences from molecular genetic data, placing them within the broader framework of quantitative genetics and life-history evolution.

  5. Sexual and natural selection both influence male genital evolution.

    PubMed

    House, Clarissa M; Lewis, Zenobia; Hodgson, Dave J; Wedell, Nina; Sharma, Manmohan D; Hunt, John; Hosken, David J

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on the genital-arch lobes of male Drosophila simulans. Replicate populations were forced to evolve under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and two temperature regimes, 25°C (relaxed natural selection) or 27°C (elevated natural selection) in a fully factorial design. We found that natural and sexual selection plus their interaction caused genital evolution. Natural selection caused some aspects of genital form to evolve away from their sexually selected shape, whereas natural and sexual selection operated in the same direction for other shape components. Additionally, sexual and natural selection tended to favour larger genitals. Thus we find that the underlying selection driving genital evolution is complex, does not only involve sexual selection, and that natural selection and sexual selection do not always act antagonistically.

  6. Sexual and Natural Selection Both Influence Male Genital Evolution

    PubMed Central

    Hodgson, Dave J.; Wedell, Nina; Sharma, Manmohan D.; Hunt, John; Hosken, David J.

    2013-01-01

    Rapid and divergent evolution of male genital morphology is a conspicuous and general pattern across internally fertilizing animals. Rapid genital evolution is thought to be the result of sexual selection, and the role of natural selection in genital evolution remains controversial. However, natural and sexual selection are believed to act antagonistically on male genital form. We conducted an experimental evolution study to investigate the combined effects of natural and sexual selection on the genital-arch lobes of male Drosophila simulans. Replicate populations were forced to evolve under lifetime monogamy (relaxed sexual selection) or lifetime polyandry (elevated sexual selection) and two temperature regimes, 25°C (relaxed natural selection) or 27°C (elevated natural selection) in a fully factorial design. We found that natural and sexual selection plus their interaction caused genital evolution. Natural selection caused some aspects of genital form to evolve away from their sexually selected shape, whereas natural and sexual selection operated in the same direction for other shape components. Additionally, sexual and natural selection tended to favour larger genitals. Thus we find that the underlying selection driving genital evolution is complex, does not only involve sexual selection, and that natural selection and sexual selection do not always act antagonistically. PMID:23717488

  7. Naturally Occurring Animal Models with Outer Retina Phenotypes

    PubMed Central

    Baehr, Wolfgang; Frederick, Jeanne M.

    2009-01-01

    Naturally occurring and laboratory generated animal models serve as powerful tools with which to investigate the etiology of human retinal degenerations, especially retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), cone dystrophies (CD) and macular degeneration (MD). Much progress has been made in elucidating gene defects underlying disease, in understanding mechanisms leading to disease, and in designing molecules for translational research and gene-based therapy to interfere with the progression of disease. Key to this progress has been study of naturally occurring murine and canine retinal degeneration mutants. This article will review the history, phenotypes and gene defects of select animal models with outer retina (photoreceptor and retinal pigment epithelium) degeneration phenotypes. PMID:19375447

  8. Widespread Natural Occurrence of Hydroxyurea in Animals

    PubMed Central

    Fraser, David I.; Liu, Kyle T.; Reid, Bryan J.; Hawkins, Emily; Sevier, Andrew; Pyle, Michelle; Robinson, Jacob W.; Ouellette, Pierre H. R.; Ballantyne, James S.

    2015-01-01

    Here we report the widespread natural occurrence of a known antibiotic and antineoplastic compound, hydroxyurea in animals from many taxonomic groups. Hydroxyurea occurs in all the organisms we have examined including invertebrates (molluscs and crustaceans), fishes from several major groups, amphibians and mammals. The species with highest concentrations was an elasmobranch (sharks, skates and rays), the little skate Leucoraja erinacea with levels up to 250 μM, high enough to have antiviral, antimicrobial and antineoplastic effects based on in vitro studies. Embryos of L. erinacea showed increasing levels of hydroxyurea with development, indicating the capacity for hydroxyurea synthesis. Certain tissues of other organisms (e.g. skin of the frog (64 μM), intestine of lobster (138 μM) gills of the surf clam (100 μM)) had levels high enough to have antiviral effects based on in vitro studies. Hydroxyurea is widely used clinically in the treatment of certain human cancers, sickle cell anemia, psoriasis, myeloproliferative diseases, and has been investigated as a potential treatment of HIV infection and its presence at high levels in tissues of elasmobranchs and other organisms suggests a novel mechanism for fighting disease that may explain the disease resistance of some groups. In light of the known production of nitric oxide from exogenously applied hydroxyurea, endogenous hydoxyurea may play a hitherto unknown role in nitric oxide dynamics. PMID:26600157

  9. Demographic parameters and natural selection.

    PubMed

    Demetrius, L

    1974-12-01

    This paper introduces two new demographic parameters, the entropy and the reproductive potential of a population. The entropy of a population measures the variability of the contribution of the different age classes to the stationary age distribution. The reproductive potential measures the mean of the contribution of the different age classes to the growth rate. Using a relation between these measures and the Malthusian parameter, it is shown that in a random mating population in Hardy-Weinberg equilibrium, and under slow selection, the rate of change of entropy is equal to the genetic variance in entropy minus the genetic covariance of entropy and reproductive potential. This result is an analogue of Fisher's fundamental theorem of natural selection.

  10. Natural Selection in Large Populations

    NASA Astrophysics Data System (ADS)

    Desai, Michael

    2011-03-01

    I will discuss theoretical and experimental approaches to the evolutionary dynamics and population genetics of natural selection in large populations. In these populations, many mutations are often present simultaneously, and because recombination is limited, selection cannot act on them all independently. Rather, it can only affect whole combinations of mutations linked together on the same chromosome. Methods common in theoretical population genetics have been of limited utility in analyzing this coupling between the fates of different mutations. In the past few years it has become increasingly clear that this is a crucial gap in our understanding, as sequence data has begun to show that selection appears to act pervasively on many linked sites in a wide range of populations, including viruses, microbes, Drosophila, and humans. I will describe approaches that combine analytical tools drawn from statistical physics and dynamical systems with traditional methods in theoretical population genetics to address this problem, and describe how experiments in budding yeast can help us directly observe these evolutionary dynamics.

  11. Symbiogenesis, natural selection, and the dynamic Earth.

    PubMed

    Kutschera, U

    2009-08-01

    One century ago, Constantin S. Mereschkowsky introduced the symbiogenesis theory for the origin of chloroplasts from ancient cyanobacteria which was later supplemented by Ivan E. Wallin's proposal that mitochondria evolved from once free-living bacteria. Today, this Mereschkowsky-Wallin principle of symbiogenesis, which is also known as the serial primary endosymbiosis theory, explains the evolutionary origin of eukaryotic cells and hence the emergence of all eukaryotes (protists, fungi, animals and plants). In 1858, the concept of natural selection was described independently by Charles Darwin and Alfred R. Wallace. In the same year, Antonio Snider-Pellegrini proposed the idea of shifting continents, which was later expanded by Alfred Wegener, who published his theory of continental drift eight decades ago. Today, directional selection is accepted as the major cause of adaptive evolution within natural populations of micro- and macro-organisms and the theory of the dynamic Earth (plate tectonics) is well supported. In this article, I combine the processes and principles of symbiogenesis, natural selection and the dynamic Earth and propose an integrative 'synade-model' of macroevolution which takes into account organisms from all five Kingdoms of life.

  12. Genomics of coloration in natural animal populations.

    PubMed

    San-Jose, Luis M; Roulin, Alexandre

    2017-07-05

    Animal coloration has traditionally been the target of genetic and evolutionary studies. However, until very recently, the study of the genetic basis of animal coloration has been mainly restricted to model species, whereas research on non-model species has been either neglected or mainly based on candidate approaches, and thereby limited by the knowledge obtained in model species. Recent high-throughput sequencing technologies allow us to overcome previous limitations, and open new avenues to study the genetic basis of animal coloration in a broader number of species and colour traits, and to address the general relevance of different genetic structures and their implications for the evolution of colour. In this review, we highlight aspects where genome-wide studies could be of major utility to fill in the gaps in our understanding of the biology and evolution of animal coloration. The new genomic approaches have been promptly adopted to study animal coloration although substantial work is still needed to consider a larger range of species and colour traits, such as those exhibiting continuous variation or based on reflective structures. We argue that a robust advancement in the study of animal coloration will also require large efforts to validate the functional role of the genes and variants discovered using genome-wide tools.This article is part of the themed issue 'Animal coloration: production, perception, function and application'. © 2017 The Author(s).

  13. Wild Origins: The Evolving Nature of Animal Behavior

    NASA Astrophysics Data System (ADS)

    Flores, Ifigenia

    For billions of years, evolution has been the driving force behind the incredible range of biodiversity on our planet. Wild Origins is a concept plan for an exhibition at the National Zoo that uses case studies of animal behavior to explain the theory of evolution. Behaviors evolve, just as physical forms do. Understanding natural selection can help us interpret animal behavior and vice-versa. A living collection, digital media, interactives, fossils, and photographs will relay stories of social behavior, sex, navigation and migration, foraging, domestication, and relationships between different species. The informal learning opportunities visitors are offered at the zoo will create a connection with the exhibition's teaching points. Visitors will leave with an understanding and sense of wonder at the evolutionary view of life.

  14. Magnetic maps in animals: nature's GPS.

    PubMed

    Lohmann, Kenneth J; Lohmann, Catherine M F; Putman, Nathan F

    2007-11-01

    Diverse animals detect the Earth's magnetic field and use it as a cue in orientation and navigation. Most research on magnetoreception has focused on the directional or ;compass' information that can be extracted from the Earth's field. Because the field varies predictably across the surface of the globe, however, it also provides a potential source of positional or 'map' information, which some animals use to steer themselves along migratory pathways or to navigate toward specific target areas. The use of magnetic positional information has been demonstrated in several diverse animals including sea turtles, spiny lobsters, newts and birds, suggesting that such systems are phylogenetically widespread and can function over a wide range of spatial scales. These ;magnetic maps' have not yet been fully characterized. They may be organized in several fundamentally different ways, some of which bear little resemblance to human maps, and they may also be used in conjunction with unconventional navigational strategies.

  15. Pitfalls in animal reproduction research: how the animal guards nature's secrets.

    PubMed

    Ginther, O J

    2013-08-01

    The estrous cycles of heifers and mares are used for illustrating pitfalls at the animal level in research in reproductive biology. Infrequent monitoring for characterizing the change in hormone concentrations or for detecting a reproductive event can be a pitfall when the interval for obtaining data exceeds the interval between events. For example, hourly collection of blood samples has shown that the luteolytic period (decreasing progesterone) encompasses 24 hours in heifers and mares. Collection of samples every 6-24 hours results in the illusion that luteolysis requires 2-3 days, owing to the occurrence of luteolysis on different days in individuals. A single treatment with PGF2α that causes complete regression of the corpus luteum is an example of an overdose pitfall. A nonphysiological progesterone increase occurs and will be misleading if used for making interpretations on the nature of luteolysis. A pitfall can also occur if a chosen reference point or end point is a poor representation of a physiological event. For example, if on a selected day after ovulation the animals in treatment A are closer on average to luteolysis than animals in treatment B, treatment A will appear to have had an earlier luteolytic effect. Among the techniques that are used directly in the animal, ultrasonography appears to be most prone to research pitfalls. Research during a given month can be confounded by seasonal effects, even in species that ovulate throughout the year. The presence of unknown factors or complex interactions among factors and the sensitivity of the animal to a research procedure separate from the direct effect of a treatment are also research challenges. A hidden factor should be considered nature's challenge to open-minded biologists but a pitfall for the close-minded.

  16. Group selection and social evolution in domesticated animals.

    PubMed

    Wade, Michael J; Bijma, Piter; Ellen, Esther D; Muir, William

    2010-09-01

    Social interactions, especially those involving competition among individuals, are important in domesticated livestock and in natural populations. The heritability of traits affected by such interactions has two components, one originating in the individual like that of classical traits (direct effects) and the other originating in other group members (indirect effects). The latter type of trait represents a significant source of 'hidden heritability' and it requires population structure and knowledge from relatives in order to access it for selective breeding. When ignored, competitive interactions may increase as an indirect response to direct selection, resulting in diminished yields. We illustrate how population genetic structure affects the response to selection of traits with indirect genetic effects using population genetic and quantitative genetic theory. Population genetic theory permits us to connect our results to the existing body of theory on kin and group selection in natural populations. The quantitative genetic perspective allows us to see how breeders have used knowledge from relatives and family selection in the domestication of plants and animals to improve the welfare and production of livestock by incorporating social genetic effects in the breeding program. We illustrate the central features of these models by reviewing empirical studies from domesticated chickens.

  17. Group selection and social evolution in domesticated animals

    PubMed Central

    Wade, Michael J; Bijma, Piter; Ellen, Esther D; Muir, William

    2010-01-01

    Social interactions, especially those involving competition among individuals, are important in domesticated livestock and in natural populations. The heritability of traits affected by such interactions has two components, one originating in the individual like that of classical traits (direct effects) and the other originating in other group members (indirect effects). The latter type of trait represents a significant source of ‘hidden heritability’ and it requires population structure and knowledge from relatives in order to access it for selective breeding. When ignored, competitive interactions may increase as an indirect response to direct selection, resulting in diminished yields. We illustrate how population genetic structure affects the response to selection of traits with indirect genetic effects using population genetic and quantitative genetic theory. Population genetic theory permits us to connect our results to the existing body of theory on kin and group selection in natural populations. The quantitative genetic perspective allows us to see how breeders have used knowledge from relatives and family selection in the domestication of plants and animals to improve the welfare and production of livestock by incorporating social genetic effects in the breeding program. We illustrate the central features of these models by reviewing empirical studies from domesticated chickens. PMID:25567938

  18. Sexual selection and genetic colour polymorphisms in animals.

    PubMed

    Wellenreuther, Maren; Svensson, Erik I; Hansson, Bengt

    2014-11-01

    Genetic colour polymorphisms are widespread across animals and often subjected to complex selection regimes. Traditionally, colour morphs were used as simple visual markers to measure allele frequency changes in nature, selection, population divergence and speciation. With advances in sequencing technology and analysis methods, several model systems are emerging where the molecular targets of selection are being described. Here, we discuss recent studies on the genetics of sexually selected colour polymorphisms, aiming at (i) reviewing the evidence of sexual selection on colour polymorphisms, (ii) highlighting the genetic architecture, molecular and developmental basis underlying phenotypic colour diversification and (iii) discuss how the maintenance of such polymorphisms might be facilitated or constrained by these. Studies of the genetic architecture of colour polymorphism point towards the importance of tight clustering of colour loci with other trait loci, such as in the case of inversions and supergene structures. Other interesting findings include linkage between colour loci and mate preferences or sex determination, and the role of introgression and regulatory variation in fuelling polymorphisms. We highlight that more studies are needed that explicitly integrate fitness consequences of sexual selection on colour with the underlying molecular targets of colour to gain insights into the evolutionary consequences of sexual selection on polymorphism maintenance. © 2014 John Wiley & Sons Ltd.

  19. Natural Selection in the Great Apes

    PubMed Central

    Cagan, Alexander; Theunert, Christoph; Laayouni, Hafid; Santpere, Gabriel; Pybus, Marc; Casals, Ferran; Prüfer, Kay; Navarro, Arcadi; Marques-Bonet, Tomas; Bertranpetit, Jaume; Andrés, Aida M.

    2016-01-01

    Natural selection is crucial for the adaptation of populations to their environments. Here, we present the first global study of natural selection in the Hominidae (humans and great apes) based on genome-wide information from population samples representing all extant species (including most subspecies). Combining several neutrality tests we create a multi-species map of signatures of natural selection covering all major types of natural selection. We find that the estimated efficiency of both purifying and positive selection varies between species and is significantly correlated with their long-term effective population size. Thus, even the modest differences in population size among the closely related Hominidae lineages have resulted in differences in their ability to remove deleterious alleles and to adapt to changing environments. Most signatures of balancing and positive selection are species-specific, with signatures of balancing selection more often being shared among species. We also identify loci with evidence of positive selection across several lineages. Notably, we detect signatures of positive selection in several genes related to brain function, anatomy, diet and immune processes. Our results contribute to a better understanding of human evolution by putting the evidence of natural selection in humans within its larger evolutionary context. The global map of natural selection in our closest living relatives is available as an interactive browser at http://tinyurl.com/nf8qmzh. PMID:27795229

  20. Natural Selection in the Great Apes.

    PubMed

    Cagan, Alexander; Theunert, Christoph; Laayouni, Hafid; Santpere, Gabriel; Pybus, Marc; Casals, Ferran; Prüfer, Kay; Navarro, Arcadi; Marques-Bonet, Tomas; Bertranpetit, Jaume; Andrés, Aida M

    2016-12-01

    Natural selection is crucial for the adaptation of populations to their environments. Here, we present the first global study of natural selection in the Hominidae (humans and great apes) based on genome-wide information from population samples representing all extant species (including most subspecies). Combining several neutrality tests we create a multi-species map of signatures of natural selection covering all major types of natural selection. We find that the estimated efficiency of both purifying and positive selection varies between species and is significantly correlated with their long-term effective population size. Thus, even the modest differences in population size among the closely related Hominidae lineages have resulted in differences in their ability to remove deleterious alleles and to adapt to changing environments. Most signatures of balancing and positive selection are species-specific, with signatures of balancing selection more often being shared among species. We also identify loci with evidence of positive selection across several lineages. Notably, we detect signatures of positive selection in several genes related to brain function, anatomy, diet and immune processes. Our results contribute to a better understanding of human evolution by putting the evidence of natural selection in humans within its larger evolutionary context. The global map of natural selection in our closest living relatives is available as an interactive browser at http://tinyurl.com/nf8qmzh. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  1. Modularity, noise, and natural selection.

    PubMed

    Marroig, Gabriel; Melo, Diogo A R; Garcia, Guilherme

    2012-05-01

    Most biological systems are formed by component parts that are to some degree interrelated. Groups of parts that are more associated among themselves and are relatively autonomous from others are called modules. One of the consequences of modularity is that biological systems usually present an unequal distribution of the genetic variation among traits. Estimating the covariance matrix that describes these systems is a difficult problem due to a number of factors such as poor sample sizes and measurement errors. We show that this problem will be exacerbated whenever matrix inversion is required, as in directional selection reconstruction analysis. We explore the consequences of varying degrees of modularity and signal-to-noise ratio on selection reconstruction. We then present and test the efficiency of available methods for controlling noise in matrix estimates. In our simulations, controlling matrices for noise vastly improves the reconstruction of selection gradients. We also perform an analysis of selection gradients reconstruction over a New World Monkeys skull database to illustrate the impact of noise on such analyses. Noise-controlled estimates render far more plausible interpretations that are in full agreement with previous results. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  2. Populations, Natural Selection, and Applied Organizational Science.

    ERIC Educational Resources Information Center

    McKelvey, Bill; Aldrich, Howard

    1983-01-01

    Deficiencies in existing models in organizational science may be remedied by applying the population approach, with its concepts of taxonomy, classification, evolution, and population ecology; and natural selection theory, with its principles of variation, natural selection, heredity, and struggle for existence, to the idea of organizational forms…

  3. Naturally occurring animal models of human hepatitis E virus infection.

    PubMed

    Yugo, Danielle M; Cossaboom, Caitlin M; Meng, Xiang-Jin

    2014-01-01

    Hepatitis E virus (HEV) is a single-stranded, positive-sense RNA virus in the family Hepeviridae. Hepatitis E caused by HEV is a clinically important global disease. There are currently four well-characterized genotypes of HEV in mammalian species, although numerous novel strains of HEV likely belonging to either new genotypes or species have recently been identified from several other animal species. HEV genotypes 1 and 2 are limited to infection in humans, whereas genotypes 3 and 4 infect an expanding host range of animal species and are zoonotic to humans. Historical animal models include various species of nonhuman primates, which have been indispensable for the discovery of human HEV and for understanding its pathogenesis and course of infection. With the genetic identification and characterization of animal strains of HEV, a number of naturally occurring animal models such as swine, chicken, and rabbit have recently been developed for various aspects of HEV research, including vaccine trials, pathogenicity, cross-species infection, mechanism of virus replication, and molecular biology studies. Unfortunately, the current available animal models for HEV are still inadequate for certain aspects of HEV research. For instance, an animal model is still lacking to study the underlying mechanism of severe and fulminant hepatitis E during pregnancy. Also, an animal model that can mimic chronic HEV infection is critically needed to study the mechanism leading to chronicity in immunocompromised individuals. Genetic identification of additional novel animal strains of HEV may lead to the development of better naturally occurring animal models for HEV. This article reviews the current understanding of animal models of HEV infection in both natural and experimental infection settings and identifies key research needs and limitations. © The Author 2014. Published by Oxford University Press on behalf of the Institute for Laboratory Animal Research. All rights reserved. For

  4. Animal Rights: Selected Resources and Suggestions for Further Study.

    ERIC Educational Resources Information Center

    Davidoff, Donald J.

    1989-01-01

    Presents an annotated list of selected resources intended to serve as a guide to the growing amount of material on animal rights. Suggestions to aid in additional research include subject headings used to find books, indexes used to locate periodical articles, sources for locating organizations, and a selected list of animal rights organizations.…

  5. Animal Rights: Selected Resources and Suggestions for Further Study.

    ERIC Educational Resources Information Center

    Davidoff, Donald J.

    1989-01-01

    Presents an annotated list of selected resources intended to serve as a guide to the growing amount of material on animal rights. Suggestions to aid in additional research include subject headings used to find books, indexes used to locate periodical articles, sources for locating organizations, and a selected list of animal rights organizations.…

  6. Teaching Animal Habitat Selection Using Wildlife Tracking Equipment

    ERIC Educational Resources Information Center

    Laskowski, Jessica; Gillespie, Caitlyn; Corral, Lucia; Oden, Amy; Fricke, Kent; Fontaine, Joseph J.

    2016-01-01

    We present a hands-on outdoor activity coupled with classroom discussion to teach students about wildlife habitat selection, the process by which animals choose where to live. By selecting locations or habitats with many benefits (e.g., food, shelter, mates) and few costs (e.g., predators), animals improve their ability to survive and reproduce.…

  7. Teaching Animal Habitat Selection Using Wildlife Tracking Equipment

    ERIC Educational Resources Information Center

    Laskowski, Jessica; Gillespie, Caitlyn; Corral, Lucia; Oden, Amy; Fricke, Kent; Fontaine, Joseph J.

    2016-01-01

    We present a hands-on outdoor activity coupled with classroom discussion to teach students about wildlife habitat selection, the process by which animals choose where to live. By selecting locations or habitats with many benefits (e.g., food, shelter, mates) and few costs (e.g., predators), animals improve their ability to survive and reproduce.…

  8. More ecological ERA: incorporating natural environmental factors and animal behavior.

    PubMed

    Bednarska, Agnieszka J; Jevtić, Dragan M; Laskowski, Ryszard

    2013-07-01

    We discuss the importance of selected natural abiotic and biotic factors in ecological risk assessment based on simplistic laboratory bioassays. Although it is impossible to include all possible natural factors in standard lower-tier ecotoxicological testing, neglecting them is not an option. Therefore, we try to identify the most important factors and advocate redesigning standard testing procedures to include theoretically most potent interactions. We also point out a few potentially important factors that have not been studied enough so far. The available data allowed us to identify temperature and O2 depletion as the most critical factors that should be included in ecotoxicity testing as soon as possible. Temporal limitations and fluctuations in food availability also appear important, but at this point more fundamental research in this area is necessary before making decisions on their inclusion in risk assessment procedures. We propose using specific experimental designs, such as Box-Behnken or Central Composite, which allow for simultaneous testing of 3 or more factors for their individual and interactive effects with greater precision and without increasing the effort and costs of tests dramatically. Factorial design can lead to more powerful tests and help to extend the validity of conclusions. Finally, ecological risk assessment procedures should include information on animal behavior, especially feeding patterns. This requires more basic studies, but already at this point adequate mechanistic effect models can be developed for some species. Copyright © 2013 SETAC.

  9. Animals and Us: How We Live Together. Nature. Teacher's Guide.

    ERIC Educational Resources Information Center

    Barker, Lucia; Brown, Jordan

    This curriculum guide was developed for use with public television's Nature series. The materials in the guide are designed to help students actively participate in the study and experience of nature. Students are encouraged to view the programs as naturalists would, observing animals in their environment, noting their behavior, and drawing…

  10. Administration of Substances to Laboratory Animals: Equipment Considerations, Vehicle Selection, and Solute Preparation

    PubMed Central

    Turner, Patricia V; Pekow, Cynthia; Vasbinder, Mary Ann; Brabb, Thea

    2011-01-01

    Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure. The equipment selected to deliver substances to animals depends on the length of the study and the nature of the material being administered. This selection provides a significant opportunity for refining animal treatment. Similarly, when substances are administered as solutions or suspensions, attention should be given to selection of vehicles and methods used for preparing the solutions and suspensions. The research team, veterinarian, technical personnel, and IACUC members should be aware of reasons underlying selection of equipment for substance delivery and should consider carefully how substances will be prepared and stored prior to administration to animals. Failure to consider these factors during experimental planning may result in unintentional adverse effects on experimental animals and confounded results. PMID:22330706

  11. Administration of substances to laboratory animals: equipment considerations, vehicle selection, and solute preparation.

    PubMed

    Turner, Patricia V; Pekow, Cynthia; Vasbinder, Mary Ann; Brabb, Thea

    2011-09-01

    Administration of substances to laboratory animals requires careful consideration and planning to optimize delivery of the agent to the animal while minimizing potential adverse experiences from the procedure. The equipment selected to deliver substances to animals depends on the length of the study and the nature of the material being administered. This selection provides a significant opportunity for refining animal treatment. Similarly, when substances are administered as solutions or suspensions, attention should be given to selection of vehicles and methods used for preparing the solutions and suspensions. The research team, veterinarian, technical personnel, and IACUC members should be aware of reasons underlying selection of equipment for substance delivery and should consider carefully how substances will be prepared and stored prior to administration to animals. Failure to consider these factors during experimental planning may result in unintentional adverse effects on experimental animals and confounded results.

  12. Student learning using the natural selection model

    NASA Astrophysics Data System (ADS)

    Mesmer, Karen Luann

    Students often have difficulty in learning natural selection, a major model in biology. This study examines what middle school students are capable of learning when taught about natural selection using a modeling approach. Students were taught the natural selection model including the components of population, variation, selective advantage, survival, heredity and reproduction. They then used the model to solve three case studies. Their learning was evaluated from responses on a pretest, a posttest and interviews. The results suggest that middle school students can identify components of the natural selection model in a Darwinian explanation, explain the significance of the components and relate them to each other as well as solve evolutionary problems using the model.

  13. Selecting an Animal for Classroom Use.

    ERIC Educational Resources Information Center

    Orlans, F. Barbara

    1980-01-01

    Listed are criteria to be considered in selecting classroom organisms for suitability in observational studies. Organisms that lend themselves to basic biological principles are also listed. Potential difficulties (safety hazards, habitat replication, confinement, food requirements, teacher's attitude, conservation, escape of nonnative species)…

  14. Selecting an Animal for Classroom Use.

    ERIC Educational Resources Information Center

    Orlans, F. Barbara

    1980-01-01

    Listed are criteria to be considered in selecting classroom organisms for suitability in observational studies. Organisms that lend themselves to basic biological principles are also listed. Potential difficulties (safety hazards, habitat replication, confinement, food requirements, teacher's attitude, conservation, escape of nonnative species)…

  15. Companion Animals, Natural Disasters and the Law: An Australian Perspective

    PubMed Central

    White, Steven

    2012-01-01

    Simple Summary One of the issues raised by recent natural disasters in Australia is the management of companion animal welfare in disaster planning, response and recovery. Official inquiries following these disasters uncovered a number of shortcomings in addressing the management of animal welfare issues. This article suggests that despite some reform following these events, disaster management still fails to take seriously the interests of companion animals. Abstract This article examines the regulation of companion animal welfare during disasters, with some context provided by two recent major disaster events in Australia. Important general lessons for improved disaster management were identified in subsequent inquiries. However, the interests of companion animals continue to be inadequately addressed. This is because key assumptions underpinning disaster planning for companion animals—the primacy of human interests over animal interests and that individuals will properly address companion animal needs during times of disaster—are open to question. In particular these assumptions fail to recognise the inherent value of companion animals, underestimate the strong bond shared by some owners and their animals and, at the same time, overestimate the capacity of some owners to adequately meet the needs of their animals. PMID:26487028

  16. Animals in surgery--surgery in animals: nature and culture in animal-human relationship and modern surgery.

    PubMed

    Schlich, Thomas; Mykhalovskiy, Eric; Rock, Melanie

    2009-01-01

    AThis paper looks at the entangled histories of animal-human relationship and modem surgery. It starts with the various different roles animals have in surgery--patients, experimental models and organ providers--and analyses where these seemingly contradictory positions of animals come from historically. The analyses is based on the assumption that both the heterogeneous relationships of humans to animals and modern surgery are the results of fundamentally local, contingent and situated developments and not reducible to large-scale social explanations, such as modernization. This change of perspective opens up a new ways of understanding both phenomena as deeply interwoven with the redrawing of the nature-culture divide.

  17. Seasonal effects of leached mirex on selected estuarine animals.

    PubMed

    Tagatz, M E; Borthwick, P W; Forester, J

    1975-01-01

    Four 28-day seasonal experiments were conducted using selected estuarine animals in outdoor tanks that received continuous flow of mirex-laden water. Mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene) leached from fire ant bait (0.3% mirex) by fresh water and then mixed with salt water was toxic to blue crabs (Callinectes sapidus), pink shrimp (Penaeus duorarum), and grass shrimp (Palaemonetes pugio) but not to sheepshead minnows (Cyprinodon variegatus), at concentrations less than 0.53 mug/L in water. The amount of leaching was greatest in summer and least in spring. Greatest mortality occurred in summer at the highest water temperature and concentration of mirex; least mortality occurred in spring at the next to the lowest temperature and at the lowest concentration. Earliest deaths of blue crabs occurred after six days of exposure and shrimps after two days. Small juvenile crabs were more sensitive to leached mirex than were large juveniles. Mirex did not appear to affect growth or frequency of molting in crabs. All exposed animals concentrated mirex. Among animals that survived for 28 days, sheepshead minnows concentrated mirex 40,800X above the concentration in the water, blue crabs 2,300X, pink shrimp 10,000X, and grass shrimp 10,800X. Sand substrata contained mirex up to 770X that in the water. Most control and exposed animals in samples examined histologically had normal tissues, but alteration in gills of some exposed fish and natural pathogens in some exposed and control crabs and shrimp were observed. The experiments demonstrated that mirex can be leached from bait by fresh water, concentrated by estuarine organisms, and can be toxic to crabs and shrimps.

  18. Natural Selection in a Petri Dish.

    ERIC Educational Resources Information Center

    McCarty, Robbie V.; Marek, Edmund A.

    1997-01-01

    Presents an activity to teach natural selection that involves students in a microbiological investigation. Students discover that a change in environmental conditions tests a species' range of adaptations. (DDR)

  19. Evoll - A Computer Based Natural Selection Game

    ERIC Educational Resources Information Center

    Wright, Ramil C.

    1972-01-01

    Describes a computer-generated natural selection game which deals with various factors influencing survival and speciation processes. Variation of population size, growth rate, brood size, and selection pressure are permitted by the program, which is written in ASA Basic FORTRAN IV. (PR)

  20. Teaching animal habitat selection using wildlife tracking equipment

    USGS Publications Warehouse

    Laskowski, Jessica; Gillespie, Caitlyn; Corral, Lucia; Oden, Amy; Fricke, Kent A.; Fontaine, Joseph J.

    2016-01-01

    We present a hands-on outdoor activity coupled with classroom discussion to teach students about wildlife habitat selection, the process by which animals choose where to live. By selecting locations or habitats with many benefits (e.g., food, shelter, mates) and few costs (e.g., predators), animals improve their ability to survive and reproduce. Biologists track animal movement using radio telemetry technology to study habitat selection so they can better provide species with habitats that promote population growth. We present a curriculum in which students locate “animals” (transmitters) using radio telemetry equipment and apply math skills (use of fractions and percentages) to assess their “animal's” habitat selection by comparing the availability of habitat types with the proportion of “animals” they find in each habitat type.

  1. Can natural selection favour altruism between species?

    PubMed

    Wyatt, G A K; West, S A; Gardner, A

    2013-09-01

    Darwin suggested that the discovery of altruism between species would annihilate his theory of natural selection. However, it has not been formally shown whether between-species altruism can evolve by natural selection, or why this could never happen. Here, we develop a spatial population genetic model of two interacting species, showing that indiscriminate between species helping can be favoured by natural selection. We then ask if this helping behaviour constitutes altruism between species, using a linear-regression analysis to separate the total action of natural selection into its direct and indirect (kin selected) components. We show that our model can be interpreted in two ways, as either altruism within species, or altruism between species. This ambiguity arises depending on whether or not we treat genes in the other species as predictors of an individual's fitness, which is equivalent to treating these individuals as agents (actors or recipients). Our formal analysis, which focuses upon evolutionary dynamics rather than agents and their agendas, cannot resolve which is the better approach. Nonetheless, because a within-species altruism interpretation is always possible, our analysis supports Darwin's suggestion that natural selection does not favour traits that provide benefits exclusively to individuals of other species.

  2. The discontinuity between humans and animals in Buffon's Natural history.

    PubMed

    Caponi, Gustavo

    2017-01-01

    According to Buffon, the difference between man's cognitive abilities and those of other animals could not be attributed to natural causes. Noting these differences necessarily meant accepting that the Creator had endowed man with an immaterial soul that was unparalleled among animals. This article seeks to show that Buffon's abandonment of naturalism was not the result of a theological premise but of the impossibility of reconciling the presumed heterogeneity between animal and human cognitive faculties with the materialist explanation of the origin of species that Buffon outlined in the course of his writings. If man is assumed to be an exceptional being, the origin of the human race must also be seen as miraculous.

  3. Microsatellites as targets of natural selection.

    PubMed

    Haasl, Ryan J; Payseur, Bret A

    2013-02-01

    The ability to survey polymorphism on a genomic scale has enabled genome-wide scans for the targets of natural selection. Theory that connects patterns of genetic variation to evidence of natural selection most often assumes a diallelic locus and no recurrent mutation. Although these assumptions are suitable to selection that targets single nucleotide variants, fundamentally different types of mutation generate abundant polymorphism in genomes. Moreover, recent empirical results suggest that mutationally complex, multiallelic loci including microsatellites and copy number variants are sometimes targeted by natural selection. Given their abundance, the lack of inference methods tailored to the mutational peculiarities of these types of loci represents a notable gap in our ability to interrogate genomes for signatures of natural selection. Previous theoretical investigations of mutation-selection balance at multiallelic loci include assumptions that limit their application to inference from empirical data. Focusing on microsatellites, we assess the dynamics and population-level consequences of selection targeting mutationally complex variants. We develop general models of a multiallelic fitness surface, a realistic model of microsatellite mutation, and an efficient simulation algorithm. Using these tools, we explore mutation-selection-drift equilibrium at microsatellites and investigate the mutational history and selective regime of the microsatellite that causes Friedreich's ataxia. We characterize microsatellite selective events by their duration and cost, note similarities to sweeps from standing point variation, and conclude that it is premature to label microsatellites as ubiquitous agents of efficient adaptive change. Together, our models and simulation algorithm provide a powerful framework for statistical inference, which can be used to test the neutrality of microsatellites and other multiallelic variants.

  4. Microsatellites as Targets of Natural Selection

    PubMed Central

    Haasl, Ryan J.; Payseur, Bret A.

    2013-01-01

    The ability to survey polymorphism on a genomic scale has enabled genome-wide scans for the targets of natural selection. Theory that connects patterns of genetic variation to evidence of natural selection most often assumes a diallelic locus and no recurrent mutation. Although these assumptions are suitable to selection that targets single nucleotide variants, fundamentally different types of mutation generate abundant polymorphism in genomes. Moreover, recent empirical results suggest that mutationally complex, multiallelic loci including microsatellites and copy number variants are sometimes targeted by natural selection. Given their abundance, the lack of inference methods tailored to the mutational peculiarities of these types of loci represents a notable gap in our ability to interrogate genomes for signatures of natural selection. Previous theoretical investigations of mutation-selection balance at multiallelic loci include assumptions that limit their application to inference from empirical data. Focusing on microsatellites, we assess the dynamics and population-level consequences of selection targeting mutationally complex variants. We develop general models of a multiallelic fitness surface, a realistic model of microsatellite mutation, and an efficient simulation algorithm. Using these tools, we explore mutation-selection-drift equilibrium at microsatellites and investigate the mutational history and selective regime of the microsatellite that causes Friedreich’s ataxia. We characterize microsatellite selective events by their duration and cost, note similarities to sweeps from standing point variation, and conclude that it is premature to label microsatellites as ubiquitous agents of efficient adaptive change. Together, our models and simulation algorithm provide a powerful framework for statistical inference, which can be used to test the neutrality of microsatellites and other multiallelic variants. PMID:23104080

  5. Caring during crisis: animal welfare during pandemics and natural disasters.

    PubMed

    Millman, Suzanne T

    2008-01-01

    From April 29 to May 1, 2007, the University of Guelph hosted a symposium, Caring During Crisis: Animal Welfare During Pandemics and Natural Disasters, with the objectives (a) of raising awareness about how nonhuman animals and the people who care for them are affected during emergencies and (b) of sharing knowledge about how animal welfare may be addressed during these situations. The symposium attracted 150 participants, representing 71 organizations from across Canada, the United States, the United Kingdom, Australia, Chile, and the Cayman Islands. The audience also brought a range of perspectives to the issues - from individuals representing animal protection and commodity organizations to municipal government officials responsible for community safety and correctional services; many of these individuals had little or no animal experience. To take advantage of this diverse audience and range of interests, the symposium was structured with formal presentations by internationally recognized experts, followed by panel discussions at the end of each session to facilitate contributions by the audience. At the conclusion of the 3 days, it was clear that our emotional, economic, and ecological relationships with animals require thoughtful integration of animal care within formal policy and planning for emergency response.

  6. A unifying framework for quantifying the nature of animal interactions.

    PubMed

    Potts, Jonathan R; Mokross, Karl; Lewis, Mark A

    2014-07-06

    Collective phenomena, whereby agent-agent interactions determine spatial patterns, are ubiquitous in the animal kingdom. On the other hand, movement and space use are also greatly influenced by the interactions between animals and their environment. Despite both types of interaction fundamentally influencing animal behaviour, there has hitherto been no unifying framework for the models proposed in both areas. Here, we construct a general method for inferring population-level spatial patterns from underlying individual movement and interaction processes, a key ingredient in building a statistical mechanics for ecological systems. We show that resource selection functions, as well as several examples of collective motion models, arise as special cases of our framework, thus bringing together resource selection analysis and collective animal behaviour into a single theory. In particular, we focus on combining the various mechanistic models of territorial interactions in the literature with step selection functions, by incorporating interactions into the step selection framework and demonstrating how to derive territorial patterns from the resulting models. We demonstrate the efficacy of our model by application to a population of insectivore birds in the Amazon rainforest.

  7. A unifying framework for quantifying the nature of animal interactions

    PubMed Central

    Potts, Jonathan R.; Mokross, Karl; Lewis, Mark A.

    2014-01-01

    Collective phenomena, whereby agent–agent interactions determine spatial patterns, are ubiquitous in the animal kingdom. On the other hand, movement and space use are also greatly influenced by the interactions between animals and their environment. Despite both types of interaction fundamentally influencing animal behaviour, there has hitherto been no unifying framework for the models proposed in both areas. Here, we construct a general method for inferring population-level spatial patterns from underlying individual movement and interaction processes, a key ingredient in building a statistical mechanics for ecological systems. We show that resource selection functions, as well as several examples of collective motion models, arise as special cases of our framework, thus bringing together resource selection analysis and collective animal behaviour into a single theory. In particular, we focus on combining the various mechanistic models of territorial interactions in the literature with step selection functions, by incorporating interactions into the step selection framework and demonstrating how to derive territorial patterns from the resulting models. We demonstrate the efficacy of our model by application to a population of insectivore birds in the Amazon rainforest. PMID:24829284

  8. Simulating natural selection in landscape genetics.

    PubMed

    Landguth, E L; Cushman, S A; Johnson, N A

    2012-03-01

    Linking landscape effects to key evolutionary processes through individual organism movement and natural selection is essential to provide a foundation for evolutionary landscape genetics. Of particular importance is determining how spatially-explicit, individual-based models differ from classic population genetics and evolutionary ecology models based on ideal panmictic populations in an allopatric setting in their predictions of population structure and frequency of fixation of adaptive alleles. We explore initial applications of a spatially-explicit, individual-based evolutionary landscape genetics program that incorporates all factors--mutation, gene flow, genetic drift and selection--that affect the frequency of an allele in a population. We incorporate natural selection by imposing differential survival rates defined by local relative fitness values on a landscape. Selection coefficients thus can vary not only for genotypes, but also in space as functions of local environmental variability. This simulator enables coupling of gene flow (governed by resistance surfaces), with natural selection (governed by selection surfaces). We validate the individual-based simulations under Wright-Fisher assumptions. We show that under isolation-by-distance processes, there are deviations in the rate of change and equilibrium values of allele frequency. The program provides a valuable tool (cdpop v1.0; http://cel.dbs.umt.edu/software/CDPOP/) for the study of evolutionary landscape genetics that allows explicit evaluation of the interactions between gene flow and selection in complex landscapes.

  9. Comparing Patterns of Natural Selection Across Species Using Selective Signatures

    SciTech Connect

    Alm, Eric J.; Shapiro, B. Jesse; Alm, Eric J.

    2007-12-18

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 gamma-proteobacterial species. We describe the pattern of fast or slow evolution across species as the 'selective signature' of a gene. Selective signatures represent a profile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example, glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  10. Comparing Patterns of Natural Selection across Species Using Selective Signatures

    SciTech Connect

    Shapiro, Jesse; Alm, Eric J.

    2007-12-01

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 c-proteobacterial species. We describe the pattern of fast or slow evolution across species as the"selective signature" of a gene. Selective signatures represent aprofile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example,glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell.

  11. Comparing Patterns of Natural Selection across Species Using Selective Signatures

    PubMed Central

    Shapiro, B. Jesse; Alm, Eric J

    2008-01-01

    Comparing gene expression profiles over many different conditions has led to insights that were not obvious from single experiments. In the same way, comparing patterns of natural selection across a set of ecologically distinct species may extend what can be learned from individual genome-wide surveys. Toward this end, we show how variation in protein evolutionary rates, after correcting for genome-wide effects such as mutation rate and demographic factors, can be used to estimate the level and types of natural selection acting on genes across different species. We identify unusually rapidly and slowly evolving genes, relative to empirically derived genome-wide and gene family-specific background rates for 744 core protein families in 30 γ-proteobacterial species. We describe the pattern of fast or slow evolution across species as the “selective signature” of a gene. Selective signatures represent a profile of selection across species that is predictive of gene function: pairs of genes with correlated selective signatures are more likely to share the same cellular function, and genes in the same pathway can evolve in concert. For example, glycolysis and phenylalanine metabolism genes evolve rapidly in Idiomarina loihiensis, mirroring an ecological shift in carbon source from sugars to amino acids. In a broader context, our results suggest that the genomic landscape is organized into functional modules even at the level of natural selection, and thus it may be easier than expected to understand the complex evolutionary pressures on a cell. PMID:18266472

  12. Complete genetic linkage can subvert natural selection

    PubMed Central

    Gerrish, Philip J.; Colato, Alexandre; Perelson, Alan S.; Sniegowski, Paul D.

    2007-01-01

    The intricate adjustment of organisms to their environment demonstrates the effectiveness of natural selection. But Darwin himself recognized that certain biological features could limit this effectiveness, features that generally reduce the efficiency of natural selection or yield suboptimal adaptation. Genetic linkage is known to be one such feature, and here we show theoretically that it can introduce a more sinister flaw: when there is complete linkage between loci affecting fitness and loci affecting mutation rate, positive natural selection and recurrent mutation can drive mutation rates in an adapting population to intolerable levels. We discuss potential implications of this finding for the early establishment of recombination, the evolutionary fate of asexual populations, and immunological clearance of clonal pathogens. PMID:17405865

  13. Darwin's explanation of design: from natural theology to natural selection.

    PubMed

    Ayala, Francisco J

    2010-08-01

    Copernicus, Galileo, Newton and other physical scientists ushered in a conception of the universe as matter in motion governed by natural laws. Their discoveries brought about a fundamental revolution, namely a commitment to the postulate that the universe obeys immanent laws that can account for natural phenomena. The workings of the universe were brought into the realm of science: explanation through natural laws. Darwin completed the Copernican revolution by extending it to the living world. Darwin demonstrated the evolution of organisms. More important yet is that he discovered natural selection, the process that explains the "design" of organisms. The adaptations and diversity of organisms, the origin of novel and complex species, even the origin of mankind, could now be explained by an orderly process of change governed by natural laws. The origin of species and the exquisite features of organisms had previously been explained as special creations of an Omniscient God. Darwin brought them into the domain of science. Evolution is a creative process that produces genuine novelty. The creative power of evolution arises from a distinctive interaction between chance and necessity, between random mutation and natural selection.

  14. Natural and sexual selection against hybrid flycatchers.

    PubMed

    Svedin, Nina; Wiley, Chris; Veen, Thor; Gustafsson, Lars; Qvarnström, Anna

    2008-03-22

    While sexual selection is generally assumed to quickly cause or strengthen prezygotic barriers between sister species, its role in causing postzygotic isolation, through the unattractiveness of intermediate hybrids, is less often examined. Combining 24 years of pedigree data and recently developed species-specific molecular markers from collared (Ficedula albicollis) and pied (Ficedula hypoleuca) flycatchers and their hybrids, we were able to quantify all key components of fitness. To disentangle the relative role of natural and sexual selection acting on F1 hybrid flycatchers, we estimated various fitness components, which when combined represent the total lifetime reproductive success of F1 hybrids, and then compared the different fitness components of F1 hybrids to that of collared flycatchers. Female hybrid flycatchers are sterile, with natural selection being the selective force involved, but male hybrids mainly experienced a reduction in fitness through sexual selection (decreased pairing success and increased rate of being cuckolded). To disentangle the role of sexual selection against male hybrids from a possible effect of genetic incompatibility (on the rate of being cuckolded), we compared male hybrids with pure-bred males expressing intermediate plumage characters. Given that sexual selection against male hybrids is a result of their intermediate plumage, we expect these two groups of males to have a similar fitness reduction. Alternatively, hybrids have reduced fitness owing to genetic incompatibility, in which case their fitness should be lower than that of the intermediate pure-bred males. We conclude that sexual selection against male hybrids accounts for approximately 75% of the reduction in their fitness. We discuss how natural and sexual selection against hybrids may have different implications for speciation and conclude that reinforcement of reproductive barriers may be more likely when there is sexual selection against hybrids.

  15. Natural and sexual selection against hybrid flycatchers

    PubMed Central

    Svedin, Nina; Wiley, Chris; Veen, Thor; Gustafsson, Lars; Qvarnström, Anna

    2008-01-01

    While sexual selection is generally assumed to quickly cause or strengthen prezygotic barriers between sister species, its role in causing postzygotic isolation, through the unattractiveness of intermediate hybrids, is less often examined. Combining 24 years of pedigree data and recently developed species-specific molecular markers from collared (Ficedula albicollis) and pied (Ficedula hypoleuca) flycatchers and their hybrids, we were able to quantify all key components of fitness. To disentangle the relative role of natural and sexual selection acting on F1 hybrid flycatchers, we estimated various fitness components, which when combined represent the total lifetime reproductive success of F1 hybrids, and then compared the different fitness components of F1 hybrids to that of collared flycatchers. Female hybrid flycatchers are sterile, with natural selection being the selective force involved, but male hybrids mainly experienced a reduction in fitness through sexual selection (decreased pairing success and increased rate of being cuckolded). To disentangle the role of sexual selection against male hybrids from a possible effect of genetic incompatibility (on the rate of being cuckolded), we compared male hybrids with pure-bred males expressing intermediate plumage characters. Given that sexual selection against male hybrids is a result of their intermediate plumage, we expect these two groups of males to have a similar fitness reduction. Alternatively, hybrids have reduced fitness owing to genetic incompatibility, in which case their fitness should be lower than that of the intermediate pure-bred males. We conclude that sexual selection against male hybrids accounts for approximately 75% of the reduction in their fitness. We discuss how natural and sexual selection against hybrids may have different implications for speciation and conclude that reinforcement of reproductive barriers may be more likely when there is sexual selection against hybrids. PMID:18211878

  16. Natural selection. IV. The Price equation*

    PubMed Central

    Frank, Steven A.

    2012-01-01

    The Price equation partitions total evolutionary change into two components. The first component provides an abstract expression of natural selection. The second component subsumes all other evolutionary processes, including changes during transmission. The natural selection component is often used in applications. Those applications attract widespread interest for their simplicity of expression and ease of interpretation. Those same applications attract widespread criticism by dropping the second component of evolutionary change and by leaving unspecified the detailed assumptions needed for a complete study of dynamics. Controversies over approximation and dynamics have nothing to do with the Price equation itself, which is simply a mathematical equivalence relation for total evolutionary change expressed in an alternative form. Disagreements about approach have to do with the tension between the relative valuation of abstract versus concrete analyses. The Price equation’s greatest value has been on the abstract side, particularly the invariance relations that illuminate the understanding of natural selection. Those abstract insights lay the foundation for applications in terms of kin selection, information theory interpretations of natural selection, and partitions of causes by path analysis. I discuss recent critiques of the Price equation by Nowak and van Veelen. PMID:22487312

  17. Neither human nor natural: ethics and feral animals.

    PubMed

    Singer, P

    1997-01-01

    There are three major ethical approaches to issues affecting nonhuman animals and the natural environment: an anthropocentric ethic, and ethic of concern for all sentient beings, and a biocentric approach. The ethic of concern for all sentient beings is the most defensible basis for resolving conflicts between the interests of humans and wild animals. There is no ethical basis for discounting the suffering of an animal simply because that being is a member of a different species. On the other hand, it is certainly true that human and nonhuman animals differ in their capacities, and this does make a difference to the ethics of what we may do to them, including rendering them infertile. Since ethics is not a matter of adhering to absolute rules, but rather of doing what will have best consequences, given the constraints under which we act, the ethics of using a specific method of fertility control for feral animals will depend on what other methods are being used, or will be used, if the given method is not available. It will also depend on the consequences of not using any method of controlling the population of the animals.

  18. Natural and Sexual Selection on Many Loci

    PubMed Central

    Barton, N. H.; Turelli, M.

    1991-01-01

    A method is developed that describes the effects on an arbitrary number of autosomal loci of selection on haploid and diploid stages, of nonrandom mating between haploid individuals, and of recombination. We provide exact recursions for the dynamics of allele frequencies and linkage disequilibria (nonrandom associations of alleles across loci). When selection is weak relative to recombination, our recursions provide simple approximations for the linkage disequilibria among arbitrary combinations of loci. We show how previous models of sex-independent natural selection on diploids, assortative mating between haploids, and sexual selection on haploids can be analyzed in this framework. Using our weak-selection approximations, we derive new results concerning the coevolution of male traits and female preferences under natural and sexual selection. In particular, we provide general expressions for the intensity of linkage-disequilibrium induced selection experienced by loci that contribute to female preferences for specific male traits. Our general results support the previous observation that these indirect selection forces are so weak that they are unlikely to dominate the evolution of preference-producing loci. PMID:2016044

  19. [Polish legal terms of animal-based research - selected aspects].

    PubMed

    Poznański, Paweł; Niedźwiecki, Sławomir

    2014-01-01

    Animal-based models used in biomedical sciences allow to perform research that, conducted on humans, would be highly problematic because of bioethical and technical issues. Contemporary researchers race can lead to abuse, hence the need for special law regulations regarding this subject. This necessity reflected both in the EU and Polish legislation, and is rooted in the philosophical and moral achievements of Europe. EU legislation in this case takes the form of directives implemented in the legal systems of the member states. Polish tradition of legislative approach to animal-based research is long. In 1959 the wide attempt to regulate this matter was undertaken. Until 2005, the nature of the matter had been regulated by the Polish animal protection law. Currently, details concerning animal-based-research are regulated by the animal experiments law (2005). The elapsed time since enactment allowed doctrine and judicature to reveal capabilities and vulnerabilities of the law.

  20. Exploiting a natural auxotrophy for genetic selection.

    PubMed

    Ramage, Elizabeth; Gallagher, Larry; Manoil, Colin

    2012-08-01

    We exploited the natural histidine auxotrophy of Francisella species to develop hisD (encodes histidinol dehydrogenase) as a positive selection marker. A shuttle plasmid (pBR103) carrying Escherichia coli hisD and designed for cloning of PCR fragments replicated in both attenuated and highly virulent Francisella strains. During this work, we formulated a simplified defined growth medium for Francisella novicida.

  1. A Lesson on Evolution & Natural Selection

    ERIC Educational Resources Information Center

    Curtis, Anthony D.

    2010-01-01

    I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

  2. Simulating natural selection in landscape genetics

    Treesearch

    E. L. Landguth; S. A. Cushman; N. Johnson

    2012-01-01

    Linking landscape effects to key evolutionary processes through individual organism movement and natural selection is essential to provide a foundation for evolutionary landscape genetics. Of particular importance is determining how spatially- explicit, individual-based models differ from classic population genetics and evolutionary ecology models based on ideal...

  3. A Lesson on Evolution & Natural Selection

    ERIC Educational Resources Information Center

    Curtis, Anthony D.

    2010-01-01

    I describe three activities that allow students to explore the ideas of evolution, natural selection, extinction, mass extinction, and rates of evolutionary change by engaging a simple model using paper, pens, chalk, and a chalkboard. As a culminating activity that supports expository writing in the sciences, the students write an essay on mass…

  4. Natural Forces as Agents: Reconceptualizing the Animate-Inanimate Distinction

    PubMed Central

    Lowder, Matthew W.; Gordon, Peter C.

    2014-01-01

    Research spanning multiple domains of psychology has demonstrated preferential processing of animate as compared to inanimate entities—a pattern that is commonly explained as due to evolutionarily adaptive behavior. Forces of nature represent a class of entities that are semantically inanimate but which behave as if they are animate in that they possess the ability to initiate movement and cause actions. We report an eye-tracking experiment demonstrating that natural forces are processed like animate entities during online sentence processing: they are easier to integrate with action verbs than instruments, and this effect is mediated by sentence structure. The results suggest that many cognitive and linguistic phenomena that have previously been attributed to animacy may be more appropriately attributed to perceived agency. To the extent that this is so, the cognitive potency of animate entities may not be due to vigilant monitoring of the environment for unpredictable events as argued by evolutionary psychologists but instead may be more adequately explained as reflecting a cognitive and linguistic focus on causal explanations that is adaptive because it increases the predictability of events. PMID:25497518

  5. Natural selection drives the evolution of ant life cycles

    PubMed Central

    Wilson, Edward O.; Nowak, Martin A.

    2014-01-01

    The genetic origin of advanced social organization has long been one of the outstanding problems of evolutionary biology. Here we present an analysis of the major steps in ant evolution, based for the first time, to our knowledge, on combined recent advances in paleontology, phylogeny, and the study of contemporary life histories. We provide evidence of the causal forces of natural selection shaping several key phenomena: (i) the relative lateness and rarity in geological time of the emergence of eusociality in ants and other animal phylads; (ii) the prevalence of monogamy at the time of evolutionary origin; and (iii) the female-biased sex allocation observed in many ant species. We argue that a clear understanding of the evolution of social insects can emerge if, in addition to relatedness-based arguments, we take into account key factors of natural history and study how natural selection acts on alleles that modify social behavior. PMID:25114217

  6. Natural selection. VII. History and interpretation of kin selection theory.

    PubMed

    Frank, S A

    2013-06-01

    Kin selection theory is a kind of causal analysis. The initial form of kin selection ascribed cause to costs, benefits and genetic relatedness. The theory then slowly developed a deeper and more sophisticated approach to partitioning the causes of social evolution. Controversy followed because causal analysis inevitably attracts opposing views. It is always possible to separate total effects into different component causes. Alternative causal schemes emphasize different aspects of a problem, reflecting the distinct goals, interests and biases of different perspectives. For example, group selection is a particular causal scheme with certain advantages and significant limitations. Ultimately, to use kin selection theory to analyse natural patterns and to understand the history of debates over different approaches, one must follow the underlying history of causal analysis. This article describes the history of kin selection theory, with emphasis on how the causal perspective improved through the study of key patterns of natural history, such as dispersal and sex ratio, and through a unified approach to demographic and social processes. Independent historical developments in the multivariate analysis of quantitative traits merged with the causal analysis of social evolution by kin selection.

  7. Missing concepts in natural selection theory reconstructions.

    PubMed

    Ginnobili, Santiago

    2016-09-01

    The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on the way the theory was put to use in Darwin's main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions.

  8. Incorporating animal spatial memory in step selection functions.

    PubMed

    Oliveira-Santos, Luiz Gustavo R; Forester, James D; Piovezan, Ubiratan; Tomas, Walfrido M; Fernandez, Fernando A S

    2016-03-01

    Memory is among the most important and neglected forces that shapes animal movement patterns. Research on the movement-memory interface is crucial to understand how animals use spatial learning to navigate across space because memory-based navigation is directly linked to animals' space use and home range behaviour; however, because memory cannot be measured directly, it is difficult to account for. Here, we incorporated spatial memory into step selection functions (SSF) to understand how resource selection and spatial memory affect space use of feral hogs (Sus scrofa). We used Biased Random Bridge kernel estimates linked to residence time as a surrogate for memory and tested four conceptually different dynamic maps of spatial memory. We applied this memory-based SSF to a data set of hog relocations to evaluate the importance of land cover type, time of day and spatial memory on the animals' space use. Our approach has shown how the incorporation of spatial memory into animal movement models can improve estimates of habitat selection. Memory-based SSF provided a feasible way to gain insight into how animals use spatial learning to guide their movement decisions. We found that while hogs selected forested areas and water bodies and avoided grasslands during the day (primarily at noon), they had a strong tendency to select previously visited areas, mainly those held in recent memory. Beyond actively updating their memory with recent experiences, hogs were able to discriminate among spatial memories encoded at different circadian phases of their activity. Even though hogs are thought to have long memory retention, they likely relied on recent experiences because the local food resources are quickly depleted and slowly renewed, yielding an uncertain spatial distribution of resources.

  9. Multivariate analysis for animal selection in experimental research.

    PubMed

    Pinto, Renan Mercuri; Campos, Dijon Henrique Salomé de; Tomasi, Loreta Casquel; Cicogna, Antonio Carlos; Okoshi, Katashi; Padovani, Carlos Roberto

    2015-02-01

    Several researchers seek methods for the selection of homogeneous groups of animals in experimental studies, a fact justified because homogeneity is an indispensable prerequisite for casualization of treatments. The lack of robust methods that comply with statistical and biological principles is the reason why researchers use empirical or subjective methods, influencing their results. To develop a multivariate statistical model for the selection of a homogeneous group of animals for experimental research and to elaborate a computational package to use it. The set of echocardiographic data of 115 male Wistar rats with supravalvular aortic stenosis (AoS) was used as an example of model development. Initially, the data were standardized, and became dimensionless. Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability. That technique established a new Cartesian system into which the animals were allocated, and finally the confidence region (ellipsoid) was built for the profile of the animals' homogeneous responses. The animals located inside the ellipsoid were considered as belonging to the homogeneous batch; those outside the ellipsoid were considered spurious. The PCA established eight descriptive axes that represented the accumulated variance of the data set in 88.71%. The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals. The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate.

  10. Darwinian natural selection: its enduring explanatory power

    PubMed Central

    2012-01-01

    Evolutionary theory has never had a stronger scientific foundation than it does today. In a short review I hope to portray the deep commitment of today's biologists to Darwinian natural selection and to discoveries made since Darwin's time. In spite of the scientific advances in the century and a half since the publication of On the Origin of Species, Darwin still remains the principal author of modern evolutionary theory. He is one of the greatest contributors of all time to our understanding of nature. PMID:22481845

  11. [Nature's healing power--natural selection in protein turnover].

    PubMed

    Pirlet, K

    2003-10-01

    For millennia, medical practitioners, healthy people and the sick have known that there is an inner force that keeps us sound and also cures us. However, neither medicine nor natural sciences have been able to define this curative power. It can not be captured by experiments or assigned with dimensions or numbers. The answer can be found in the quintessential process of all living systems, the interaction of genes and proteins in every single cell. Genes encode proteins; proteins are the ubiquitous instruments of life. Protein molecules undergo rapid turnover: their median lifetime is about 2 days, and in every second so many proteins are synthesized in each of us that their number equals the number of seconds that have passed since the big bang 15 billion years ago. The biochemical dogma that says that after their synthesis proteins are degraded at random - blindly, quasi - is wrong. The experimental results have not been interpreted correctly. In the first instance, proteins are stable and functional, since they have to fulfill numerous tasks. Only aged, severely damaged, non-functioning proteins are discarded. Protein turnover is subject to selection, not to chance. By selecting fresh, functional proteins, the quality of cellular proteins is kept at a high level. The principle of selection in protein turnover is the crucial component in the scientific groundwork of naturopathy therapeutics. With natural influencies and measures (e.g. food processing, intermediate metabolism, exercise, light, warmth, coldness) the steady process of regeneration is accelerated - in contrast to medical therapy, which restricts and blocks protein activities. Natural healing power and self-organization energy are basic phenomena of a therapeutically used physiology. Naturopathy is natural science. Copyright 2003 S. Karger GmbH, Freiburg

  12. Reported health conditions in animals residing near natural gas wells in southwestern Pennsylvania.

    PubMed

    Slizovskiy, I B; Conti, L A; Trufan, S J; Reif, J S; Lamers, V T; Stowe, M H; Dziura, J; Rabinowitz, P M

    2015-01-01

    Natural gas extraction activities, including the use of horizontal drilling and hydraulic fracturing, may pose potential health risks to both human and animal populations in close proximity to sites of extraction activity. Because animals may have increased exposure to contaminated water and air as well as increased susceptibility to contaminant exposures compared to nearby humans, animal disease events in communities living near natural gas extraction may provide "sentinel" information useful for human health risk assessment. Community health evaluations as well as health impact assessments (HIAs) of natural gas exploration should therefore consider the inclusion of animal health metrics in their assessment process. We report on a community environmental health survey conducted in an area of active natural gas drilling, which included the collection of health data on 2452 companion and backyard animals residing in 157 randomly-selected households of Washington County, Pennsylvania (USA). There were a total of 127 reported health conditions, most commonly among dogs. When reports from all animals were considered, there were no significant associations between reported health condition and household proximity to natural gas wells. When dogs were analyzed separately, we found an elevated risk of 'any' reported health condition in households less than 1km from the nearest gas well (OR = 3.2, 95% CI 1.07-9.7), with dermal conditions being the most common of canine disorders. While these results should be considered hypothesis generating and preliminary, they suggest value in ongoing assessments of pet dogs as well as other animals to better elucidate the health impacts of natural gas extraction on nearby communities.

  13. Modelling with words: Narrative and natural selection.

    PubMed

    Dimech, Dominic K

    2017-02-18

    I argue that verbal models should be included in a philosophical account of the scientific practice of modelling. Weisberg (2013) has directly opposed this thesis on the grounds that verbal structures, if they are used in science, only merely describe models. I look at examples from Darwin's On the Origin of Species (1859) of verbally constructed narratives that I claim model the general phenomenon of evolution by natural selection. In each of the cases I look at, a particular scenario is described that involves at least some fictitious elements but represents the salient causal components of natural selection. I pronounce the importance of prioritising observation of scientific practice for the philosophy of modelling and I suggest that there are other likely model types that are excluded from philosophical accounts.

  14. Multivariate Analysis for Animal Selection in Experimental Research

    PubMed Central

    Pinto, Renan Mercuri; de Campos, Dijon Henrique Salomé; Tomasi, Loreta Casquel; Cicogna, Antonio Carlos; Okoshi, Katashi; Padovani, Carlos Roberto

    2015-01-01

    Background Several researchers seek methods for the selection of homogeneous groups of animals in experimental studies, a fact justified because homogeneity is an indispensable prerequisite for casualization of treatments. The lack of robust methods that comply with statistical and biological principles is the reason why researchers use empirical or subjective methods, influencing their results. Objective To develop a multivariate statistical model for the selection of a homogeneous group of animals for experimental research and to elaborate a computational package to use it. Methods The set of echocardiographic data of 115 male Wistar rats with supravalvular aortic stenosis (AoS) was used as an example of model development. Initially, the data were standardized, and became dimensionless. Then, the variance matrix of the set was submitted to principal components analysis (PCA), aiming at reducing the parametric space and at retaining the relevant variability. That technique established a new Cartesian system into which the animals were allocated, and finally the confidence region (ellipsoid) was built for the profile of the animals’ homogeneous responses. The animals located inside the ellipsoid were considered as belonging to the homogeneous batch; those outside the ellipsoid were considered spurious. Results The PCA established eight descriptive axes that represented the accumulated variance of the data set in 88.71%. The allocation of the animals in the new system and the construction of the confidence region revealed six spurious animals as compared to the homogeneous batch of 109 animals. Conclusion The biometric criterion presented proved to be effective, because it considers the animal as a whole, analyzing jointly all parameters measured, in addition to having a small discard rate. PMID:25651342

  15. Human task animation from performance models and natural language input

    NASA Technical Reports Server (NTRS)

    Esakov, Jeffrey; Badler, Norman I.; Jung, Moon

    1989-01-01

    Graphical manipulation of human figures is essential for certain types of human factors analyses such as reach, clearance, fit, and view. In many situations, however, the animation of simulated people performing various tasks may be based on more complicated functions involving multiple simultaneous reaches, critical timing, resource availability, and human performance capabilities. One rather effective means for creating such a simulation is through a natural language description of the tasks to be carried out. Given an anthropometrically-sized figure and a geometric workplace environment, various simple actions such as reach, turn, and view can be effectively controlled from language commands or standard NASA checklist procedures. The commands may also be generated by external simulation tools. Task timing is determined from actual performance models, if available, such as strength models or Fitts' Law. The resulting action specification are animated on a Silicon Graphics Iris workstation in real-time.

  16. Nullomers: Really a Matter of Natural Selection?

    PubMed Central

    Acquisti, Claudia; Poste, George; Curtiss, David; Kumar, Sudhir

    2007-01-01

    Background Nullomers are short DNA sequences that are absent from the genomes of humans and other species. Assuming that nullomers are the signatures of natural selection against deleterious sequences in humans, the use of nullomers in drug target identification, pesticide development, environmental monitoring, and forensic applications has been envisioned. Results Here, we show that the hypermutability of CpG dinucleotides, rather than the natural selection against the nullomer sequences, is likely the reason for the phenomenal event of short sequence motifs becoming nullomers. Furthermore, many reported human nullomers differ by only one nucleotide, which reinforces the role of mutation in the evolution of the constellation of nullomers in populations and species. The known nullomers in chimpanzee, cow, dog, and mouse genomes show patterns that are consistent with those seen in humans. Conclusions The role of mutations, instead of selection, in generating nullomers cast doubt on the utility of nullomers in many envisioned applications, because of their dependence on the role of lethal selection on the origin of nullomers. PMID:17925870

  17. Detecting natural selection in genomic data.

    PubMed

    Vitti, Joseph J; Grossman, Sharon R; Sabeti, Pardis C

    2013-01-01

    The past fifty years have seen the development and application of numerous statistical methods to identify genomic regions that appear to be shaped by natural selection. These methods have been used to investigate the macro- and microevolution of a broad range of organisms, including humans. Here, we provide a comprehensive outline of these methods, explaining their conceptual motivations and statistical interpretations. We highlight areas of recent and future development in evolutionary genomics methods and discuss ongoing challenges for researchers employing such tests. In particular, we emphasize the importance of functional follow-up studies to characterize putative selected alleles and the use of selection scans as hypothesis-generating tools for investigating evolutionary histories.

  18. Ethical and Animal Welfare Considerations in Relation to Species Selection for Animal Experimentation

    PubMed Central

    Webster, John

    2014-01-01

    Simple Summary When making a choice of species for animal experimentation we must balance its suitability as a model for human medicine against the potential harms to the animals both from the procedures and the quality of their lifetime experience. The capacity to experience pain may be similar in mammals, birds and fish. The capacity to suffer from fear is governed more by sentience than cognitive ability, so it cannot be assumed that rodents or farm animals suffer less than dogs or primates. I suggest that it is unethical to base the choice of species for animal experimentation simply on the basis that it will cause less distress within society. Abstract Ethical principles governing the conduct of experiments with animals are reviewed, especially those relating to the choice of species. Legislation requires that the potential harm to animals arising from any procedure should be assessed in advance and justified in terms of its possible benefit to society. Potential harms may arise both from the procedures and the quality of the animals’ lifetime experience. The conventional approach to species selection is to use animals with the “lowest degree of neurophysiological sensitivity”. However; this concept should be applied with extreme caution in the light of new knowledge. The capacity to experience pain may be similar in mammals, birds and fish. The capacity to suffer from fear is governed more by sentience than cognitive ability, so it cannot be assumed that rodents or farm animals suffer less than dogs or primates. I suggest that it is unethical to base the choice of species for animal experimentation simply on the basis that it will cause less distress within society. A set of responsibilities is outlined for each category of moral agent. These include regulators, operators directly concerned with the conduct of scientific experiments and toxicology trials, veterinarians and animal care staff; and society at large. PMID:26479009

  19. Ethical and Animal Welfare Considerations in Relation to Species Selection for Animal Experimentation.

    PubMed

    Webster, John

    2014-12-03

    Ethical principles governing the conduct of experiments with animals are reviewed, especially those relating to the choice of species. Legislation requires that the potential harm to animals arising from any procedure should be assessed in advance and justified in terms of its possible benefit to society. Potential harms may arise both from the procedures and the quality of the animals' lifetime experience. The conventional approach to species selection is to use animals with the "lowest degree of neurophysiological sensitivity". However; this concept should be applied with extreme caution in the light of new knowledge. The capacity to experience pain may be similar in mammals, birds and fish. The capacity to suffer from fear is governed more by sentience than cognitive ability, so it cannot be assumed that rodents or farm animals suffer less than dogs or primates. I suggest that it is unethical to base the choice of species for animal experimentation simply on the basis that it will cause less distress within society. A set of responsibilities is outlined for each category of moral agent. These include regulators, operators directly concerned with the conduct of scientific experiments and toxicology trials, veterinarians and animal care staff; and society at large.

  20. Selection of artificial gravity by animals during suborbital rocket flights.

    PubMed

    Lange, K O; Belleville, R E; Clark, F C

    1975-06-01

    White rats selected preferred artificial gravity levels by locomotion in centrifuges consisting of two runways mounted in the nose of sounding rockets. Roll rate of the Aerobee 150A rocket was designed to produce an angular velocity of 45 r.p.m. during 5 min of free-fall, providing a gravity range range from 0.3 to 1.5 G depending on a subject's runway position. One animal was released at the high and one at the low gravity position in each flight. Animal positions were continuously recorded. Flight subjects were selected from about 100 trained animals adapted to the simulated launch environment for several months. In two flights excessive rollrates produced gravity ranges above the designed limits. In two other flights the desired range was produced. Locomotion patterns during these flights were similar. All four animals explored the entire available G-range. One rat settled at 0.4 G after 2 min; the others crossed the 1-G location in progressively narrower excursions and were near earth gravity at the end of the test period. Data were more varible than in laboratory tests above 1 G and the observation periods were necessarily few and short. Tentatively, however, the data suggest that normal earth-reared rats select earth gravity when available magnitudes include values above and below 1 B. Modification of gravity preference by prolonged exposure to higher or lower levels remains a possibility.

  1. Natural Vitamin D Content in Animal Products1

    PubMed Central

    Schmid, Alexandra; Walther, Barbara

    2013-01-01

    Humans derive most vitamin D from the action of sunlight in their skin. However, in view of the current Western lifestyle with most daily activities taking place indoors, sun exposure is often not sufficient for adequate vitamin D production. For this reason, dietary intake is also of great importance. Animal foodstuffs (e.g., fish, meat, offal, egg, dairy) are the main sources for naturally occurring cholecalciferol (vitamin D-3). This paper therefore aims to provide an up-to-date overview of vitamin D-3 content in various animal foods. The focus lies on the natural vitamin D-3 content because there are many countries in which foods are not regularly fortified with vitamin D. The published data show that the highest values of vitamin D are found in fish and especially in fish liver, but offal also provides considerable amounts of vitamin D. The content in muscle meat is generally much lower. Vitamin D concentrations in egg yolks range between the values for meat and offal. If milk and dairy products are not fortified, they are normally low in vitamin D, with the exception of butter because of its high fat content. However, as recommendations for vitamin D intake have recently been increased considerably, it is difficult to cover the requirements solely by foodstuffs. PMID:23858093

  2. Natural selection and age-structured populations.

    PubMed

    Demetrius, L

    1975-03-01

    This paper studies the properties of a new class of demographic parameters for age-structured populations and analyzes the effect of natural selection on these parameters. Two new demographic variables are introduced: the entropy of a population and the reproductive potential. The entropy of a population measures the variability of the contribution of the different age classes to the stationary population. The reproductive potential measures the mean of the contribution of the different age classes to the Malthusian parameter. The Malthusian parameter is precisely the difference between the entropy and the reproductive potential. The effect of these demographic variables on changes in gene frequency is discussed. The concept of entropy of a genotype is introduced and it is shown that in a random mating population in Hardy-Weinberg equilibrium and under slow selection, the rate of change of entropy is equal to the genetic variance in entropy minus the covariance in entropy and reproductive potential. This result is an information theoretic analog of Fisher's fundamental theorem of natural selection.

  3. Natural selection and cultural rates of change.

    PubMed

    Rogers, Deborah S; Ehrlich, Paul R

    2008-03-04

    It has been claimed that a meaningful theory of cultural evolution is not possible because human beliefs and behaviors do not follow predictable patterns. However, theoretical models of cultural transmission and observations of the development of societies suggest that patterns in cultural evolution do occur. Here, we analyze whether two sets of related cultural traits, one tested against the environment and the other not, evolve at different rates in the same populations. Using functional and symbolic design features for Polynesian canoes, we show that natural selection apparently slows the evolution of functional structures, whereas symbolic designs differentiate more rapidly. This finding indicates that cultural change, like genetic evolution, can follow theoretically derived patterns.

  4. Naturally acidified habitat selects for ocean acidification-tolerant mussels.

    PubMed

    Thomsen, Jörn; Stapp, Laura S; Haynert, Kristin; Schade, Hanna; Danelli, Maria; Lannig, Gisela; Wegner, K Mathias; Melzner, Frank

    2017-04-01

    Ocean acidification severely affects bivalves, especially their larval stages. Consequently, the fate of this ecologically and economically important group depends on the capacity and rate of evolutionary adaptation to altered ocean carbonate chemistry. We document successful settlement of wild mussel larvae (Mytilus edulis) in a periodically CO2-enriched habitat. The larval fitness of the population originating from the CO2-enriched habitat was compared to the response of a population from a nonenriched habitat in a common garden experiment. The high CO2-adapted population showed higher fitness under elevated Pco2 (partial pressure of CO2) than the non-adapted cohort, demonstrating, for the first time, an evolutionary response of a natural mussel population to ocean acidification. To assess the rate of adaptation, we performed a selection experiment over three generations. CO2 tolerance differed substantially between the families within the F1 generation, and survival was drastically decreased in the highest, yet realistic, Pco2 treatment. Selection of CO2-tolerant F1 animals resulted in higher calcification performance of F2 larvae during early shell formation but did not improve overall survival. Our results thus reveal significant short-term selective responses of traits directly affected by ocean acidification and long-term adaptation potential in a key bivalve species. Because immediate response to selection did not directly translate into increased fitness, multigenerational studies need to take into consideration the multivariate nature of selection acting in natural habitats. Combinations of short-term selection with long-term adaptation in populations from CO2-enriched versus nonenriched natural habitats represent promising approaches for estimating adaptive potential of organisms facing global change.

  5. Naturally acidified habitat selects for ocean acidification–tolerant mussels

    PubMed Central

    Thomsen, Jörn; Stapp, Laura S.; Haynert, Kristin; Schade, Hanna; Danelli, Maria; Lannig, Gisela; Wegner, K. Mathias; Melzner, Frank

    2017-01-01

    Ocean acidification severely affects bivalves, especially their larval stages. Consequently, the fate of this ecologically and economically important group depends on the capacity and rate of evolutionary adaptation to altered ocean carbonate chemistry. We document successful settlement of wild mussel larvae (Mytilus edulis) in a periodically CO2-enriched habitat. The larval fitness of the population originating from the CO2-enriched habitat was compared to the response of a population from a nonenriched habitat in a common garden experiment. The high CO2–adapted population showed higher fitness under elevated Pco2 (partial pressure of CO2) than the non-adapted cohort, demonstrating, for the first time, an evolutionary response of a natural mussel population to ocean acidification. To assess the rate of adaptation, we performed a selection experiment over three generations. CO2 tolerance differed substantially between the families within the F1 generation, and survival was drastically decreased in the highest, yet realistic, Pco2 treatment. Selection of CO2-tolerant F1 animals resulted in higher calcification performance of F2 larvae during early shell formation but did not improve overall survival. Our results thus reveal significant short-term selective responses of traits directly affected by ocean acidification and long-term adaptation potential in a key bivalve species. Because immediate response to selection did not directly translate into increased fitness, multigenerational studies need to take into consideration the multivariate nature of selection acting in natural habitats. Combinations of short-term selection with long-term adaptation in populations from CO2-enriched versus nonenriched natural habitats represent promising approaches for estimating adaptive potential of organisms facing global change. PMID:28508039

  6. Can natural selection encode Bayesian priors?

    PubMed

    Ramírez, Juan Camilo; Marshall, James A R

    2017-08-07

    The evolutionary success of many organisms depends on their ability to make decisions based on estimates of the state of their environment (e.g., predation risk) from uncertain information. These decision problems have optimal solutions and individuals in nature are expected to evolve the behavioural mechanisms to make decisions as if using the optimal solutions. Bayesian inference is the optimal method to produce estimates from uncertain data, thus natural selection is expected to favour individuals with the behavioural mechanisms to make decisions as if they were computing Bayesian estimates in typically-experienced environments, although this does not necessarily imply that favoured decision-makers do perform Bayesian computations exactly. Each individual should evolve to behave as if updating a prior estimate of the unknown environment variable to a posterior estimate as it collects evidence. The prior estimate represents the decision-maker's default belief regarding the environment variable, i.e., the individual's default 'worldview' of the environment. This default belief has been hypothesised to be shaped by natural selection and represent the environment experienced by the individual's ancestors. We present an evolutionary model to explore how accurately Bayesian prior estimates can be encoded genetically and shaped by natural selection when decision-makers learn from uncertain information. The model simulates the evolution of a population of individuals that are required to estimate the probability of an event. Every individual has a prior estimate of this probability and collects noisy cues from the environment in order to update its prior belief to a Bayesian posterior estimate with the evidence gained. The prior is inherited and passed on to offspring. Fitness increases with the accuracy of the posterior estimates produced. Simulations show that prior estimates become accurate over evolutionary time. In addition to these 'Bayesian' individuals, we also

  7. The natural selection of bad science.

    PubMed

    Smaldino, Paul E; McElreath, Richard

    2016-09-01

    Poor research design and data analysis encourage false-positive findings. Such poor methods persist despite perennial calls for improvement, suggesting that they result from something more than just misunderstanding. The persistence of poor methods results partly from incentives that favour them, leading to the natural selection of bad science. This dynamic requires no conscious strategizing-no deliberate cheating nor loafing-by scientists, only that publication is a principal factor for career advancement. Some normative methods of analysis have almost certainly been selected to further publication instead of discovery. In order to improve the culture of science, a shift must be made away from correcting misunderstandings and towards rewarding understanding. We support this argument with empirical evidence and computational modelling. We first present a 60-year meta-analysis of statistical power in the behavioural sciences and show that power has not improved despite repeated demonstrations of the necessity of increasing power. To demonstrate the logical consequences of structural incentives, we then present a dynamic model of scientific communities in which competing laboratories investigate novel or previously published hypotheses using culturally transmitted research methods. As in the real world, successful labs produce more 'progeny,' such that their methods are more often copied and their students are more likely to start labs of their own. Selection for high output leads to poorer methods and increasingly high false discovery rates. We additionally show that replication slows but does not stop the process of methodological deterioration. Improving the quality of research requires change at the institutional level.

  8. Selection of artificial gravity by animals during suborbital rocket flights

    NASA Technical Reports Server (NTRS)

    Lange, K. O.; Belleville, R. E.; Clark, F. C.

    1975-01-01

    White rats selected preferred artificial gravity levels by locomotion in centrifuges consisting of two runways mounted in the nose of sounding rockets. Roll rate of the Aerobee 150A rocket was designed to produce an angular velocity of 45 rpm during 5 min of free-fall, providing a gravity range from 0.3 to 1.5 G depending on a subject's runway position. One animal was released at the high and one at the low gravity position in each flight. Animal positions were continuously recorded. Locomotion patterns during these flights were similar. All four animals explored the entire available G-range. One rat settled at 0.4 G after 2 min; the others crossed the 1-G location in progressively narrower excursions and were near earth gravity at the end of the test period. Tentatively, the data suggest that normal earth-reared rats select earth gravity when available magnitudes include values above and below 1 G. Modification of gravity preference by prolonged exposure to higher or lower levels remains a possibility.

  9. Selection of artificial gravity by animals during suborbital rocket flights

    NASA Technical Reports Server (NTRS)

    Lange, K. O.; Belleville, R. E.; Clark, F. C.

    1975-01-01

    White rats selected preferred artificial gravity levels by locomotion in centrifuges consisting of two runways mounted in the nose of sounding rockets. Roll rate of the Aerobee 150A rocket was designed to produce an angular velocity of 45 rpm during 5 min of free-fall, providing a gravity range from 0.3 to 1.5 G depending on a subject's runway position. One animal was released at the high and one at the low gravity position in each flight. Animal positions were continuously recorded. Locomotion patterns during these flights were similar. All four animals explored the entire available G-range. One rat settled at 0.4 G after 2 min; the others crossed the 1-G location in progressively narrower excursions and were near earth gravity at the end of the test period. Tentatively, the data suggest that normal earth-reared rats select earth gravity when available magnitudes include values above and below 1 G. Modification of gravity preference by prolonged exposure to higher or lower levels remains a possibility.

  10. Natural selection and cultural rates of change

    PubMed Central

    Rogers, Deborah S.; Ehrlich, Paul R.

    2008-01-01

    It has been claimed that a meaningful theory of cultural evolution is not possible because human beliefs and behaviors do not follow predictable patterns. However, theoretical models of cultural transmission and observations of the development of societies suggest that patterns in cultural evolution do occur. Here, we analyze whether two sets of related cultural traits, one tested against the environment and the other not, evolve at different rates in the same populations. Using functional and symbolic design features for Polynesian canoes, we show that natural selection apparently slows the evolution of functional structures, whereas symbolic designs differentiate more rapidly. This finding indicates that cultural change, like genetic evolution, can follow theoretically derived patterns. PMID:18287028

  11. The natural selection of bad science

    PubMed Central

    2016-01-01

    Poor research design and data analysis encourage false-positive findings. Such poor methods persist despite perennial calls for improvement, suggesting that they result from something more than just misunderstanding. The persistence of poor methods results partly from incentives that favour them, leading to the natural selection of bad science. This dynamic requires no conscious strategizing—no deliberate cheating nor loafing—by scientists, only that publication is a principal factor for career advancement. Some normative methods of analysis have almost certainly been selected to further publication instead of discovery. In order to improve the culture of science, a shift must be made away from correcting misunderstandings and towards rewarding understanding. We support this argument with empirical evidence and computational modelling. We first present a 60-year meta-analysis of statistical power in the behavioural sciences and show that power has not improved despite repeated demonstrations of the necessity of increasing power. To demonstrate the logical consequences of structural incentives, we then present a dynamic model of scientific communities in which competing laboratories investigate novel or previously published hypotheses using culturally transmitted research methods. As in the real world, successful labs produce more ‘progeny,’ such that their methods are more often copied and their students are more likely to start labs of their own. Selection for high output leads to poorer methods and increasingly high false discovery rates. We additionally show that replication slows but does not stop the process of methodological deterioration. Improving the quality of research requires change at the institutional level. PMID:27703703

  12. Selection of AUG initiation codons differs in plants and animals.

    PubMed Central

    Lütcke, H A; Chow, K C; Mickel, F S; Moss, K A; Kern, H F; Scheele, G A

    1987-01-01

    The influence of the nucleotide at position -3 relative to the AUG initiation codon on the initiation of protein synthesis was studied in two different in vitro translation systems using synthetic mRNAs. The four mRNAs, transcribed from cDNAs directed by an SP6 promoter, were identical except for mutations at nucleotide -3. In each case, translation of mRNAs produced a single protein of Mr = 12,600. Relative translational efficiencies showed a hierarchy in the reticulocyte lysate system (100, 85, 61 and 38% for A, G, U and C in position -3, respectively) but no differences in the wheat germ system. Differential mRNA degradation or polypeptide chain elongation were excluded as causes of the differences observed in translation in the reticulocyte lysate. mRNA competition increased the differences observed in translational efficiencies in reticulocyte lysate but showed no effect in wheat germ. Analysis of 61 plant and 209 animal mRNA sequences revealed qualitative and quantitative differences between the consensus sequences surrounding AUG initiation codons. Whereas the consensus sequence for animals was CACCAUG that for plants was AACAAUGGC. Both the structural and functional findings suggest that the factors which select AUG initiation codons in plants and animals differ significantly. Images Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:3556162

  13. Companion Animals, Natural Disasters and the Law: An Australian Perspective.

    PubMed

    White, Steven

    2012-08-27

    This article examines the regulation of companion animal welfare during disasters, with some context provided by two recent major disaster events in Australia. Important general lessons for improved disaster management were identified in subsequent inquiries. However, the interests of companion animals continue to be inadequately addressed. This is because key assumptions underpinning disaster planning for companion animals-the primacy of human interests over animal interests and that individuals will properly address companion animal needs during times of disaster-are open to question. In particular these assumptions fail to recognise the inherent value of companion animals, underestimate the strong bond shared by some owners and their animals and, at the same time, overestimate the capacity of some owners to adequately meet the needs of their animals.

  14. Bridging Emergent Attributes and Darwinian Principles in Teaching Natural Selection

    ERIC Educational Resources Information Center

    Xu, Dongchen; Chi, Michelene T. H.

    2016-01-01

    Students often have misconceptions about natural selection as they misuse a direct causal schema to explain the process. Natural selection is in fact an emergent process where random interactions lead to changes in a population. The misconceptions stem from students' lack of emergent schema for natural selection. In order to help students…

  15. Using Card Games to Simulate the Process of Natural Selection

    ERIC Educational Resources Information Center

    Grilliot, Matthew E.; Harden, Siegfried

    2014-01-01

    In 1858, Darwin published "On the Origin of Species by Means of Natural Selection." His explanation of evolution by natural selection has become the unifying theme of biology. We have found that many students do not fully comprehend the process of evolution by natural selection. We discuss a few simple games that incorporate hands-on…

  16. Using Card Games to Simulate the Process of Natural Selection

    ERIC Educational Resources Information Center

    Grilliot, Matthew E.; Harden, Siegfried

    2014-01-01

    In 1858, Darwin published "On the Origin of Species by Means of Natural Selection." His explanation of evolution by natural selection has become the unifying theme of biology. We have found that many students do not fully comprehend the process of evolution by natural selection. We discuss a few simple games that incorporate hands-on…

  17. Natural selection and the elusiveness of happiness.

    PubMed Central

    Nesse, Randolph M

    2004-01-01

    The quest for happiness has expanded from a focus on relieving suffering to also considering how to promote happiness. However, both approaches have yet to be conducted in an evolutionary framework based on the situations that shaped the capacities for happiness and sadness. Because of this, the emphasis has almost all been on the disadvantages of negative states and the benefits of positive states, to the nearly total neglect of 'diagonal psychology', which also considers the dangers of unwarranted positive states and the benefits of negative emotions in certain situations. The situations that arise in goal pursuit contain adaptive challenges that have shaped domain-general positive and negative emotions that were partially differentiated by natural selection to cope with the more specific situations that arise in the pursuit of different kinds of goals. In cultures where large social groups give rise to specialized and competitive social roles, depression may be common because regulation systems are pushed far beyond the bounds for which they were designed. Research on the evolutionary origins of the capacities for positive and negative emotions is urgently needed to provide a foundation for sensible decisions about the use of new mood-manipulating technologies. PMID:15347525

  18. Natural selection and the elusiveness of happiness.

    PubMed

    Nesse, Randolph M

    2004-09-29

    The quest for happiness has expanded from a focus on relieving suffering to also considering how to promote happiness. However, both approaches have yet to be conducted in an evolutionary framework based on the situations that shaped the capacities for happiness and sadness. Because of this, the emphasis has almost all been on the disadvantages of negative states and the benefits of positive states, to the nearly total neglect of 'diagonal psychology', which also considers the dangers of unwarranted positive states and the benefits of negative emotions in certain situations. The situations that arise in goal pursuit contain adaptive challenges that have shaped domain-general positive and negative emotions that were partially differentiated by natural selection to cope with the more specific situations that arise in the pursuit of different kinds of goals. In cultures where large social groups give rise to specialized and competitive social roles, depression may be common because regulation systems are pushed far beyond the bounds for which they were designed. Research on the evolutionary origins of the capacities for positive and negative emotions is urgently needed to provide a foundation for sensible decisions about the use of new mood-manipulating technologies.

  19. [Natural selection and medical triage: everyday realities].

    PubMed

    Carpentier, J P; Petrognani, R; Raynal, M; Ponchel, C; Saby, R

    2002-01-01

    Most emergency care facilities in tropical areas are inefficient, underequipped, and quickly overwhelmed by the ever-growing attendance. As a result, mortality is higher than in developed countries. To speak in terms of natural selection would be tantamount to a fatalistic admission of powerlessness to deal with the situation. In Africa, the gross imbalance between supply and demand makes it necessary to make hard choices in order to make the most effective use of available staff and equipment. The objective of medical triage is to allocate scarce facilities to those patients with the greatest chance of survival. However it is difficult to define precise rules for making such choices since they are strongly dependent on available resources, type of pathology, and level of medical skill. Prognostic indicators are ill-suited to emergency situation since they require not only clinical data but also and above all, in most cases, laboratory data which is not always available or justifiable. Experience is probably the best guarantee for reliable triage, which is philosophically difficult to accept but often unavoidable in everyday practice.

  20. Does natural selection favour the Rescorla-Wagner rule?

    PubMed

    Trimmer, Pete C; McNamara, John M; Houston, Alasdair I; Marshall, James A R

    2012-06-07

    A fundamental question relating to animal behaviour is how animals learn; in particular, how they come to associate stimuli with rewards. Numerous empirical findings can be explained by assuming that animals use some mechanism similar to the Rescorla-Wagner learning rule, which is a relatively simple and highly general method of updating the associative strength between different stimuli. However, the Rescorla-Wagner rule is often not optimal, which raises the question of why a rule with such properties should have evolved. We consider the evolution of learning rules in a simple environment where there exists an optimal rule of similar complexity to the Rescorla-Wagner rule. We show that because the Rescorla-Wagner rule is less sensitive to changes in its parameters than the optimal rule, there is a wider range of parameter values over which the rule structure is initially viable. Consequently, the Rescorla-Wagner rule can be favoured by natural selection, ahead of other rules which are more accurate.

  1. Microbial Resistance to Triclosan: A Case Study in Natural Selection

    ERIC Educational Resources Information Center

    Serafini, Amanda; Matthews, Dorothy M.

    2009-01-01

    Natural selection is the mechanism of evolution caused by the environmental selection of organisms most fit to reproduce, sometimes explained as "survival of the fittest." An example of evolution by natural selection is the development of bacteria that are resistant to antimicrobial agents as a result of exposure to these agents. Triclosan, which…

  2. Microbial Resistance to Triclosan: A Case Study in Natural Selection

    ERIC Educational Resources Information Center

    Serafini, Amanda; Matthews, Dorothy M.

    2009-01-01

    Natural selection is the mechanism of evolution caused by the environmental selection of organisms most fit to reproduce, sometimes explained as "survival of the fittest." An example of evolution by natural selection is the development of bacteria that are resistant to antimicrobial agents as a result of exposure to these agents. Triclosan, which…

  3. Using Animation to Convey Natural Hazards and Anthropogenic Change

    NASA Astrophysics Data System (ADS)

    Kerlow, I.

    2016-12-01

    Moving images are a powerful medium for analyzing, exploring and visually communicating complex concepts, and they are also the premiere medium for contemporary storytelling. Animation is particularly adept for explaining complex concepts and also for creating emotional messages. On a practical level animation can be free from the production constraints and the expense of live action filming. This presentation shows and explains new Earth-inspired animated sequences produced by the Art+Media Research Group at the Earth Observatory of Singapore. These animations have been used in a variety of interdisciplinary projects with multiple roles: sometimes to clearly explain a concept, others to elicit a feeling, or to present an emotion that facilitates learning. The projects reviewed range from scientific documentaries, to narrative shorts and interactive games. http://art-science-media.com/

  4. Using Animation to Convey Natural Hazards and Anthropogenic Change

    NASA Astrophysics Data System (ADS)

    Kerlow, Isaac

    2016-04-01

    Moving images are a powerful medium for analyzing, exploring and visually communicating complex concepts, and they are also the premiere medium for contemporary storytelling. Animation is particularly adept for explaining complex concepts and also for creating emotional messages. On a practical level animation can be free from the production constraints and the expense of live action filming. This presentation shows and explains a variety of Earth-inspired animated sequences produced by the Art+Media Research Group at the Earth Observatory of Singapore. These animations have been used in a variety of interdisciplinary projects with multiple roles: sometimes to clearly explain a concept, others to elicit a feeling, or to present an emotion that facilitates learning. The projects reviewed range from scientific documentaries, to narrative shorts and interactive games. http://art-science-media.com/

  5. Animal density and track counts: understanding the nature of observations based on animal movements.

    PubMed

    Keeping, Derek; Pelletier, Rick

    2014-01-01

    Counting animals to estimate their population sizes is often essential for their management and conservation. Since practitioners frequently rely on indirect observations of animals, it is important to better understand the relationship between such indirect indices and animal abundance. The Formozov-Malyshev-Pereleshin (FMP) formula provides a theoretical foundation for understanding the relationship between animal track counts and the true density of species. Although this analytical method potentially has universal applicability wherever animals are readily detectable by their tracks, it has long been unique to Russia and remains widely underappreciated. In this paper, we provide a test of the FMP formula by isolating the influence of animal travel path tortuosity (i.e., convolutedness) on track counts. We employed simulations using virtual and empirical data, in addition to a field test comparing FMP estimates with independent estimates from line transect distance sampling. We verify that track counts (total intersections between animals and transects) are determined entirely by density and daily movement distances. Hence, the FMP estimator is theoretically robust against potential biases from specific shapes or patterns of animal movement paths if transects are randomly situated with respect to those movements (i.e., the transects do not influence animals' movements). However, detectability (the detection probability of individual animals) is not determined simply by daily travel distance but also by tortuosity, so ensuring that all intersections with transects are counted regardless of the number of individual animals that made them becomes critical for an accurate density estimate. Additionally, although tortuosity has no bearing on mean track encounter rates, it does affect encounter rate variance and therefore estimate precision. We discuss how these fundamental principles made explicit by the FMP formula have widespread implications for methods of

  6. Selective leak-detector for natural gas

    SciTech Connect

    Bonne, U.

    1985-03-26

    An improved detector for combustible gases and which is able to discriminate between natural gas (methane and ethane) and other sources of methane (e.g. swamp gas, petrochemical and automotive) or other combustible gases by measuring the characteristic methane/ethane ratio of natural gas, based on infrared absorption of methane and ethane, in combination with another non-specific combustible gas detector.

  7. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    SciTech Connect

    Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

    2007-05-15

    In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

  8. Natural selection stops the evolution of male attractiveness.

    PubMed

    Hine, Emma; McGuigan, Katrina; Blows, Mark W

    2011-03-01

    Sexual selection in natural populations acts on highly heritable traits and tends to be relatively strong, implicating sexual selection as a causal agent in many phenotypic radiations. Sexual selection appears to be ineffectual in promoting phenotypic divergence among contemporary natural populations, however, and there is little evidence from artificial selection experiments that sexual fitness can evolve. Here, we demonstrate that a multivariate male trait preferred by Drosophila serrata females can respond to selection and results in the maintenance of male mating success. The response to selection was associated with a gene of major effect increasing in frequency from 12 to 35% in seven generations. No further response to selection, or increase in frequency of the major gene, was observed between generations 7 and 11, indicating an evolutionary limit had been reached. Genetic analyses excluded both depletion of genetic variation and overdominance as causes of the evolutionary limit. Relaxing artificial selection resulted in the loss of 52% of the selection response after a further five generations, demonstrating that the response under artificial sexual selection was opposed by antagonistic natural selection. We conclude that male D. serrata sexually selected traits, and attractiveness to D. serrata females conferred by these traits, were held at an evolutionary limit by the lack of genetic variation that would allow an increase in sexual fitness while simultaneously maintaining nonsexual fitness. Our results suggest that sexual selection is unlikely to cause divergence among natural populations without a concomitant change in natural selection, a conclusion consistent with observational evidence from natural populations.

  9. Natural selection stops the evolution of male attractiveness

    PubMed Central

    Hine, Emma; McGuigan, Katrina; Blows, Mark W.

    2011-01-01

    Sexual selection in natural populations acts on highly heritable traits and tends to be relatively strong, implicating sexual selection as a causal agent in many phenotypic radiations. Sexual selection appears to be ineffectual in promoting phenotypic divergence among contemporary natural populations, however, and there is little evidence from artificial selection experiments that sexual fitness can evolve. Here, we demonstrate that a multivariate male trait preferred by Drosophila serrata females can respond to selection and results in the maintenance of male mating success. The response to selection was associated with a gene of major effect increasing in frequency from 12 to 35% in seven generations. No further response to selection, or increase in frequency of the major gene, was observed between generations 7 and 11, indicating an evolutionary limit had been reached. Genetic analyses excluded both depletion of genetic variation and overdominance as causes of the evolutionary limit. Relaxing artificial selection resulted in the loss of 52% of the selection response after a further five generations, demonstrating that the response under artificial sexual selection was opposed by antagonistic natural selection. We conclude that male D. serrata sexually selected traits, and attractiveness to D. serrata females conferred by these traits, were held at an evolutionary limit by the lack of genetic variation that would allow an increase in sexual fitness while simultaneously maintaining nonsexual fitness. Our results suggest that sexual selection is unlikely to cause divergence among natural populations without a concomitant change in natural selection, a conclusion consistent with observational evidence from natural populations. PMID:21321197

  10. Animal Density and Track Counts: Understanding the Nature of Observations Based on Animal Movements

    PubMed Central

    Keeping, Derek; Pelletier, Rick

    2014-01-01

    Counting animals to estimate their population sizes is often essential for their management and conservation. Since practitioners frequently rely on indirect observations of animals, it is important to better understand the relationship between such indirect indices and animal abundance. The Formozov-Malyshev-Pereleshin (FMP) formula provides a theoretical foundation for understanding the relationship between animal track counts and the true density of species. Although this analytical method potentially has universal applicability wherever animals are readily detectable by their tracks, it has long been unique to Russia and remains widely underappreciated. In this paper, we provide a test of the FMP formula by isolating the influence of animal travel path tortuosity (i.e., convolutedness) on track counts. We employed simulations using virtual and empirical data, in addition to a field test comparing FMP estimates with independent estimates from line transect distance sampling. We verify that track counts (total intersections between animals and transects) are determined entirely by density and daily movement distances. Hence, the FMP estimator is theoretically robust against potential biases from specific shapes or patterns of animal movement paths if transects are randomly situated with respect to those movements (i.e., the transects do not influence animals’ movements). However, detectability (the detection probability of individual animals) is not determined simply by daily travel distance but also by tortuosity, so ensuring that all intersections with transects are counted regardless of the number of individual animals that made them becomes critical for an accurate density estimate. Additionally, although tortuosity has no bearing on mean track encounter rates, it does affect encounter rate variance and therefore estimate precision. We discuss how these fundamental principles made explicit by the FMP formula have widespread implications for methods of

  11. Natural Selection, Nutrition Research, and Science Teaching.

    ERIC Educational Resources Information Center

    Nelson, Darby

    1980-01-01

    Provides examples of the teaching of hypothesis generation and scientific inquiry in biology. Specifically, the author applies the selection paradigm to considerations of the human nutrient-handling apparatus, finally suggesting a model of the selective forces that may have operated on the human genome since hunting-gathering and primitive…

  12. Natural Selection, Nutrition Research, and Science Teaching.

    ERIC Educational Resources Information Center

    Nelson, Darby

    1980-01-01

    Provides examples of the teaching of hypothesis generation and scientific inquiry in biology. Specifically, the author applies the selection paradigm to considerations of the human nutrient-handling apparatus, finally suggesting a model of the selective forces that may have operated on the human genome since hunting-gathering and primitive…

  13. Sexual selection and natural selection in bird speciation

    PubMed Central

    Price, T.

    1998-01-01

    The role of sexual selection in speciation is investigated, addressing two main issues. First, how do sexually selected traits become species recognition traits? Theory and empirical evidence suggest that female preferences often do not evolve as a correlated response to evolution of male traits. This implies that, contrary to runaway (Fisherian) models of sexual selection, premating isolation will not arise as an automatic side effect of divergence between populations in sexually selected traits. I evaluate premating isolating mechanisms in one group, the birds. In this group premating isolation is often a consequence of sexual imprinting, whereby young birds learn features of their parents and use these features in mate choice. Song, morphology and plumage are known recognition cues. I conclude that perhaps the main role for sexual selection in speciation is in generating differences between populations in traits. Sexual imprinting then leads to these traits being used as species recognition mechanisms. The second issue addressed in this paper is the role of sexual selection in adaptive radiation, again concentrating on birds. Ecological differences between species include large differences in size, which may in themselves be sufficient for species recognition, and differences in habitat, which seem to evolve frequently and at all stages of an adaptive radiation. Differences in habitat often cause song and plumage patterns to evolve as a result of sexual selection for efficient communication. Therefore sexual selection is likely to have an important role in generating premating isolating mechanisms throughout an adaptive radiation. It is also possible that sexual selection, by creating more allopatric species, creates more opportunity for ecological divergence to occur. The limited available evidence does not support this idea. A role for sexual selection in accelerating ecological diversification has yet to be demonstrated.

  14. Natural infection by endoparasites among free-living wild animals.

    PubMed

    Holsback, Luciane; Cardoso, Mauro José Lahm; Fagnani, Rafael; Patelli, Thaís Helena Constantino

    2013-01-01

    The objective of this study was to investigate the frequency of occurrence and variety of intestinal parasites among free-living wild animals. Fecal samples from wild mammals and birds at rehabilitation centers in the states of Mato Grosso do Sul and São Paulo were analyzed by sedimentation and flotation-centrifugation methods. Parasite eggs, oocysts, cysts and/or trophozoites were found in 71% of the samples. Cryptosporidium sp. oocysts were detected in fecal samples from oncillas (Leopardus tigrinus) and scaly-headed parrots (Pionus maximiliani). Giardia cysts were identified in the feces of a gray brocket (Mazama gouazoubira). Among the most common parasites found, there were eggs from Toxocara cati, Toxascaris leonina and Ancylostoma tubaeforme, and from Cestoda. Several Enterobius sp. eggs were found in the feces of red howler monkeys (Alouatta seniculus). It can be concluded from this study that despite the small number of samples, the diversity of parasites found was noteworthy. Additional information about parasite endofauna in wild animals is needed, since their presence might suggest that there could be proximity to and interactions with domestic animals and/or humans. In addition, further studies on parasites from free-living wild animals are of prime importance for understanding the intensity of anthropic changes in wild environments.

  15. The effects of natural variation in background radioactivity on humans, animals and other organisms.

    PubMed

    Møller, Anders P; Mousseau, Timothy A

    2013-02-01

    Natural levels of radioactivity on the Earth vary by more than a thousand-fold; this spatial heterogeneity may suffice to create heterogeneous effects on physiology, mutation and selection. We review the literature on the relationship between variation in natural levels of radioactivity and evolution. First, we consider the effects of natural levels of radiation on mutations, DNA repair and genetics. A total of 46 studies with 373 effect size estimates revealed a small, but highly significant mean effect that was independent of adjustment for publication bias. Second, we found different mean effect sizes when studies were based on broad categories like physiology, immunology and disease frequency; mean weighted effect sizes were larger for studies of plants than animals, and larger in studies conducted in areas with higher levels of radiation. Third, these negative effects of radiation on mutations, immunology and life history are inconsistent with a general role of hormetic positive effects of radiation on living organisms. Fourth, we reviewed studies of radiation resistance among taxa. These studies suggest that current levels of natural radioactivity may affect mutational input and thereby the genetic constitution and composition of natural populations. Susceptibility to radiation varied among taxa, and several studies provided evidence of differences in susceptibility among populations or strains. Crucially, however, these studies are few and scattered, suggesting that a concerted effort to address this lack of research should be made. © 2012 The Authors. Biological Reviews © 2012 Cambridge Philosophical Society.

  16. Population Genetics and Natural Selection in Rheumatic Disease.

    PubMed

    Ramos, Paula S

    2017-08-01

    Human genetic diversity is the result of population genetic forces. This genetic variation influences disease risk and contributes to health disparities. Natural selection is an important influence on human genetic variation. Because immune and inflammatory function genes are enriched for signals of positive selection, the prevalence of rheumatic disease-risk alleles seen in different populations is partially the result of differing selective pressures (eg, due to pathogens). This review summarizes the genetic regions associated with susceptibility to different rheumatic diseases and concomitant evidence for natural selection, including known agents of selection exerting selective pressure in these regions. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Sensitivity of Students to the Natural Environment, Animals, Social Problems and Cultural Heritage

    ERIC Educational Resources Information Center

    Kurtdede Fidan, Nuray

    2016-01-01

    The study aims to determine the sensitivity levels of fourth-grade students to the natural environment, animals, social concerns and cultural heritage. Besides, it has been investigated whether some personal characteristics of the students have differentiating effect on the views related to the sensitivity to the natural environment, animals,…

  18. Natural Selection in the Field and the Classroom

    ERIC Educational Resources Information Center

    Andrews, Tessa Marie

    2012-01-01

    This dissertation examined natural selection in westslope cutthroat trout ("Oncorhynchus clarkii lewisi") and undergraduate learning in the subject area natural selection. Translocation--moving individuals to a new habitat to establish, re-establish or supplement a population--is a crucial management strategy for cutthroat trout. One of…

  19. Are Humans Still Evolving? A Natural Selection Discussion Lesson

    ERIC Educational Resources Information Center

    Shields, Martin

    2004-01-01

    A study is conducted to develop sound comprehension of natural selection theory by prompting students to use its concept to explain the evolutionary status of humans. In relation to the current existence of human it is stated that human populations currently undergo microevolutionary changes in allele frequencies due to natural selection and other…

  20. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  1. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Thagard, Paul; Findlay, Scott

    2010-01-01

    Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

  2. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  3. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Thagard, Paul; Findlay, Scott

    2010-01-01

    Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

  4. Development and Evaluation of the Conceptual Inventory of Natural Selection.

    ERIC Educational Resources Information Center

    Anderson, Dianne L.; Fisher, Kathleen M.; Norman, Gregory J.

    2002-01-01

    Presents a diagnostic test to assess students' understanding of natural selection. Field-tests the Conceptual Inventory of Natural Selection (CINS) with nonmajors and biology majors at community colleges. Compares test scores of nonmajors with performances in interviews and discusses the correlation between the test scores and the interview…

  5. Are Humans Still Evolving? A Natural Selection Discussion Lesson

    ERIC Educational Resources Information Center

    Shields, Martin

    2004-01-01

    A study is conducted to develop sound comprehension of natural selection theory by prompting students to use its concept to explain the evolutionary status of humans. In relation to the current existence of human it is stated that human populations currently undergo microevolutionary changes in allele frequencies due to natural selection and other…

  6. Natural Selection in the Field and the Classroom

    ERIC Educational Resources Information Center

    Andrews, Tessa Marie

    2012-01-01

    This dissertation examined natural selection in westslope cutthroat trout ("Oncorhynchus clarkii lewisi") and undergraduate learning in the subject area natural selection. Translocation--moving individuals to a new habitat to establish, re-establish or supplement a population--is a crucial management strategy for cutthroat trout. One of…

  7. Natural selection can favour 'irrational' behaviour.

    PubMed

    McNamara, J M; Trimmer, P C; Houston, A I

    2014-01-01

    Understanding decisions is the fundamental aim of the behavioural sciences. The theory of rational choice is based on axiomatic principles such as transitivity and independence of irrelevant alternatives (IIA). Empirical studies have demonstrated that the behaviour of humans and other animals often seems irrational; there can be a lack of transitivity in choice and seemingly irrelevant alternatives can alter decisions. These violations of transitivity and IIA undermine rational choice theory. However, we show that an individual that is maximizing its rate of food gain can exhibit failure of transitivity and IIA. We show that such violations can be caused because a current option may disappear in the near future or a better option may reappear soon. Current food options can be indicative of food availability in the near future, and this key feature can result in apparently irrational behaviour.

  8. Animal genomics in natural reservoirs of infectious diseases.

    PubMed

    Cowled, C; Wang, L-F

    2016-04-01

    Natural virus reservoirs such as wild bats, birds, rodents and non-human primates are generally non-model organisms that have, until recently, presented limited opportunities for in-depth study. Next-generation sequencing provides a way to partially circumvent this limitation, since the methods required for data acquisition and analysis are largely species-independent. Comparative genomics and other 'omics' provide new opportunities to study the structure and function of various biological systems of wild species that are otherwise out of reach. Genomes of natural reservoir hosts can help to identify dominant pathways of virus-host interaction and to reveal differences between susceptible and resistant organisms, populations and species. This is of great scientific interest and may also provide a resource for the rational design of treatments for viral diseases in humans and livestock. In this way, we will 'learn from nature' and one day apply this knowledge to create disease-resistant livestock or develop novel therapeutic and prevention strategies. Reservoir host genomics will also open up possibilities for developing novel vaccines for wildlife, aid in the development of new diagnostic platforms, and have broad implications for developmental and evolutionary biology. In this review, the authors focus on natural reservoir hosts of viral pathogens, although most of the discussion points should be equally applicable to natural reservoirs of pathogenic bacteria, fungi or other parasites.

  9. Linkage and the Limits to Natural Selection

    PubMed Central

    Barton, N. H.

    1995-01-01

    The probability of fixation of a favorable mutation is reduced if selection at other loci causes inherited variation in fitness. A general method for calculating the fixation probability of an allele that can find itself in a variety of genetic backgrounds is applied to find the effect of substitutions, fluctuating polymorphisms, and deleterious mutations in a large population. With loose linkage, r, the effects depend on the additive genetic variance in relative fitness, var (W), and act by reducing effective population size by (N/N(e)) = 1 + var (W)/2r(2). However, tightly linked loci can have a substantial effect not predictable from N(e). Linked deleterious mutations reduce the fixation probability of weakly favored alleles by exp(-2U/R), where U is the total mutation rate and R is the map length in Morgans. Substitutions can cause a greater reduction: an allele with advantage s < s(crit) = (π(2)/6) log(e) (S/s)[var(W)/R] is very unlikely to be fixed. (S is the advantage of the substitution impeding fixation.) Fluctuating polymorphisms at many (n) linked loci can also have a substantial effect, reducing fixation probability by exp [ &2Kn var(W)/R] [K = -1/E((u - u)(2)/uv) depending on the frequencies (u,v) at the selected polymorphisms]. Hitchhiking due to all three kinds of selection may substantially impede adaptation that depends on weakly favored alleles. PMID:7498757

  10. The moral animal: virtue, vice, and human nature.

    PubMed

    Paulson, Steve; Berlin, Heather A; Miller, Christian B; Shermer, Michael

    2016-11-01

    In Leo Tolstoy's famous novella, The Death of Ivan Ilyich, a rich and meaningful inner life is sacrificed in pursuit of material rewards and social status. How can we cultivate something intrinsic that transcends our worldly accomplishments? Assuming that a basic model or map of human nature is needed to navigate the road to the good life, what desires, tendencies, and aversions constitute our core nature? How has our evolutionary history shaped our moral impulses? Are we inherently good or fundamentally flawed? Steve Paulson, executive producer and host of To the Best of Our Knowledge, moderated a discussion with philosopher Christian Miller, neuroscientist Heather Berlin, and historian of science Michael Shermer to examine our moral ecology and its influence on our underlying assumptions about human nature.

  11. Nature in the Classroom: Rare and Endangered Animals

    ERIC Educational Resources Information Center

    Doyle, Charles

    1977-01-01

    It is important that students become aware of the enormous impact that man has upon his environment and that they become concerned and participate in activities which will help them develop responsibile attitudes toward the natural world. Presents an ecology lesson and a conservation lesson with suggested teaching guides. (Author/RK)

  12. Pharmacokinetics and metabolism of natural methylxanthines in animal and man.

    PubMed

    Arnaud, Maurice J

    2011-01-01

    Caffeine, theophylline, theobromine, and paraxanthine administered to animals and humans distribute in all body fluids and cross all biological membranes. They do not accumulate in organs or tissues and are extensively metabolized by the liver, with less than 2% of caffeine administered excreted unchanged in human urine. Dose-independent and dose-dependent pharmacokinetics of caffeine and other dimethylxanthines may be observed and explained by saturation of metabolic pathways and impaired elimination due to the immaturity of hepatic enzyme and liver diseases. While gender and menstrual cycle have little effect on their elimination, decreased clearance is seen in women using oral contraceptives and during pregnancy. Obesity, physical exercise, diseases, and particularly smoking and the interactions of drugs affect their elimination owing to either stimulation or inhibition of CYP1A2. Their metabolic pathways exhibit important quantitative and qualitative differences in animal species and man. Chronic ingestion or restriction of caffeine intake in man has a small effect on their disposition, but dietary constituents, including broccoli and herbal tea, as well as alcohol were shown to modify their plasma pharmacokinetics. Using molar ratios of metabolites in plasma and/or urine, phenotyping of various enzyme activities, such as cytochrome monooxygenases, N-acetylation, 8-hydroxylation, and xanthine oxidase, has become a valuable tool to identify polymorphisms and to understand individual variations and potential associations with health risks in epidemiological surveys.

  13. Using the Animal Model to Accelerate Response to Selection in a Self-Pollinating Crop

    PubMed Central

    Cowling, Wallace A.; Stefanova, Katia T.; Beeck, Cameron P.; Nelson, Matthew N.; Hargreaves, Bonnie L. W.; Sass, Olaf; Gilmour, Arthur R.; Siddique, Kadambot H. M.

    2015-01-01

    We used the animal model in S0 (F1) recurrent selection in a self-pollinating crop including, for the first time, phenotypic and relationship records from self progeny, in addition to cross progeny, in the pedigree. We tested the model in Pisum sativum, the autogamous annual species used by Mendel to demonstrate the particulate nature of inheritance. Resistance to ascochyta blight (Didymella pinodes complex) in segregating S0 cross progeny was assessed by best linear unbiased prediction over two cycles of selection. Genotypic concurrence across cycles was provided by pure-line ancestors. From cycle 1, 102/959 S0 plants were selected, and their S1 self progeny were intercrossed and selfed to produce 430 S0 and 575 S2 individuals that were evaluated in cycle 2. The analysis was improved by including all genetic relationships (with crossing and selfing in the pedigree), additive and nonadditive genetic covariances between cycles, fixed effects (cycles and spatial linear trends), and other random effects. Narrow-sense heritability for ascochyta blight resistance was 0.305 and 0.352 in cycles 1 and 2, respectively, calculated from variance components in the full model. The fitted correlation of predicted breeding values across cycles was 0.82. Average accuracy of predicted breeding values was 0.851 for S2 progeny of S1 parent plants and 0.805 for S0 progeny tested in cycle 2, and 0.878 for S1 parent plants for which no records were available. The forecasted response to selection was 11.2% in the next cycle with 20% S0 selection proportion. This is the first application of the animal model to cyclic selection in heterozygous populations of selfing plants. The method can be used in genomic selection, and for traits measured on S0-derived bulks such as grain yield. PMID:25943522

  14. Canine evolution in sabretoothed carnivores: natural selection or sexual selection?

    PubMed

    Randau, Marcela; Carbone, Chris; Turvey, Samuel T

    2013-01-01

    The remarkable elongated upper canines of extinct sabretoothed carnivorous mammals have been the subject of considerable speculation on their adaptive function, but the absence of living analogues prevents any direct inference about their evolution. We analysed scaling relationships of the upper canines of 20 sabretoothed feliform carnivores (Nimravidae, Barbourofelidae, Machairodontinae), representing both dirk-toothed and scimitar-toothed sabretooth ecomorphs, and 33 non-sabretoothed felids in relation to body size in order to characterize and identify the evolutionary processes driving their development, using the scaling relationships of carnassial teeth in both groups as a control. Carnassials display isometric allometry in both sabretooths and non-sabretooths, supporting their close relationship with meat-slicing, whereas the upper canines of both groups display positive allometry with body size. Whereas there is no statistical difference in allometry of upper canine height between dirk-toothed and scimitar-toothed sabretooth ecomorphs, the significantly stronger positive allometry of upper canine height shown by sabretooths as a whole compared to non-sabretooths reveals that different processes drove canine evolution in these groups. Although sabretoothed canines must still have been effective for prey capture and processing by hypercarnivorous predators, canine morphology in these extinct carnivores was likely to have been driven to a greater extent by sexual selection than in non-sabretooths. Scaling relationships therefore indicate the probable importance of sexual selection in the evolution of the hypertrophied sabretooth anterior dentition.

  15. What is adaptation by natural selection? Perspectives of an experimental microbiologist.

    PubMed

    Lenski, Richard E

    2017-04-01

    Ever since Darwin, the role of natural selection in shaping the morphological, physiological, and behavioral adaptations of animals and plants across generations has been central to understanding life and its diversity. New discoveries have shown with increasing precision how genetic, molecular, and biochemical processes produce and express those organismal features during an individual's lifetime. When it comes to microorganisms, however, understanding the role of natural selection in producing adaptive solutions has historically been, and sometimes continues to be, contentious. This tension is curious because microbes enable one to observe the power of adaptation by natural selection with exceptional rigor and clarity, as exemplified by the burgeoning field of experimental microbial evolution. I trace the development of this field, describe an experiment with Escherichia coli that has been running for almost 30 years, and highlight other experiments in which natural selection has led to interesting dynamics and adaptive changes in microbial populations.

  16. Natural selective attention: Orienting and emotion

    PubMed Central

    BRADLEY, MARGARET M.

    2013-01-01

    The foundations of orienting and attention are hypothesized to stem from activation of defensive and appetitive motivational systems that evolved to protect and sustain the life of the individual. Motivational activation initiates a cascade of perceptual and motor processes that facilitate the selection of appropriate behavior. Among these are detection of significance, indexed by a late centro-parietal positivity in the event-related potential, enhanced perceptual processing, indexed by a initial cardiac deceleration, and preparation for action, indexed by electrodermal changes. Data exploring the role of stimulus novelty and significance in orienting are presented that indicate different components of the orienting response habituate at different rates. Taken together, it is suggested that orienting is mediated by activation of fundamental motivational systems that have evolved to support survival. PMID:18778317

  17. Apoptosis and the selective survival of host animals following thermal bleaching in zooxanthellate corals.

    PubMed

    Tchernov, Dan; Kvitt, Hagit; Haramaty, Liti; Bibby, Thomas S; Gorbunov, Maxim Y; Rosenfeld, Hanna; Falkowski, Paul G

    2011-06-14

    During the past several decades, numerous reports from disparate geographical areas have documented an increased frequency of "bleaching" in reef-forming corals. The phenomenon, triggered by increased sea surface temperatures, occurs when the cnidarian hosts digest and/or expel their intracellular, photosynthetic dinoflagellate symbionts ("zooxanthellae" in the genus Symbiodinium). Although coral bleaching is often followed by the death of the animal hosts, in some cases, the animal survives and can be repopulated with viable zooxanthellae. The physiological factors determining the ability of the coral to survive bleaching events are poorly understood. In this study, we experimentally established that bleaching and death of the host animal involve a caspase-mediated apoptotic cascade induced by reactive oxygen species produced primarily by the algal symbionts. In addition, we demonstrate that, although some corals naturally suppress caspase activity and significantly reduce caspase concentration under high temperatures as a mechanism to prevent colony death from apoptosis, even sensitive corals can be prevented from dying by application of exogenous inhibitors of caspases. Our results indicate that variability in response to thermal stress in corals is determined by a four-element, combinatorial genetic matrix intrinsic to the specific symbiotic association. Based on our experimental data, we present a working model in which the phenotypic expression of this symbiont/host relationship places a selective pressure on the symbiotic association. The model predicts the survival of the host animals in which the caspase-mediated apoptotic cascade is down-regulated.

  18. Selection of natural autoreactive B cells.

    PubMed

    Hardy, Richard R; Hayakawa, Kyoko

    2015-01-01

    Natural antibodies produced by CD5+ B1 B cells include anti-thymocyte autoantibody (ATA). Transgenic mice bearing the Ig-μ heavy chain of a prototypic ATA, V(H)3609Vκ21c, demonstrated a critical requirement for self-antigen in the accumulation of ATA B cells and production of high levels of serum ATA. Further work with ATA-μκ transgenic mice revealed that, while development of most B cells were blocked at an immature stage in spleen, some mature ATA B cells were present. ATA-μκ transgenic mice with varying levels of Thy-1 autoantigen showed a clear relationship between BCR crosslinking and B cell fate, with low levels generating marginal zone ATA B cells and complete antigen absence allowing maturation to follicular ATA B cells. Finally, different fates of developing ATA B cells encountering high levels self-antigen may be accounted for by variations in the response of newly formed B cells arising from foetal and adult development.

  19. Bayesian natural selection and the evolution of perceptual systems.

    PubMed Central

    Geisler, Wilson S; Diehl, Randy L

    2002-01-01

    In recent years, there has been much interest in characterizing statistical properties of natural stimuli in order to better understand the design of perceptual systems. A fruitful approach has been to compare the processing of natural stimuli in real perceptual systems with that of ideal observers derived within the framework of Bayesian statistical decision theory. While this form of optimization theory has provided a deeper understanding of the information contained in natural stimuli as well as of the computational principles employed in perceptual systems, it does not directly consider the process of natural selection, which is ultimately responsible for design. Here we propose a formal framework for analysing how the statistics of natural stimuli and the process of natural selection interact to determine the design of perceptual systems. The framework consists of two complementary components. The first is a maximum fitness ideal observer, a standard Bayesian ideal observer with a utility function appropriate for natural selection. The second component is a formal version of natural selection based upon Bayesian statistical decision theory. Maximum fitness ideal observers and Bayesian natural selection are demonstrated in several examples. We suggest that the Bayesian approach is appropriate not only for the study of perceptual systems but also for the study of many other systems in biology. PMID:12028784

  20. Natural selection on floral morphology can be influenced by climate

    PubMed Central

    Campbell, Diane R.; Powers, John M.

    2015-01-01

    Climate has the potential to influence evolution, but how it influences the strength or direction of natural selection is largely unknown. We quantified the strength of selection on four floral traits of the subalpine herb Ipomopsis sp. in 10 years that differed in precipitation, causing extreme temporal variation in the date of snowmelt in the Colorado Rocky Mountains. The chosen floral traits were under selection by hummingbird and hawkmoth pollinators, with hawkmoth abundance highly variable across years. Selection for flower length showed environmental sensitivity, with stronger selection in years with later snowmelt, as higher water resources can allow translation of pollination success into fitness based on seed production. Selection on corolla width also varied across years, favouring narrower corolla tubes in two unusual years with hawkmoths, and wider corollas in another late snowmelt year. Our results illustrate how changes in climate could alter natural selection even when the primary selective agent is not directly influenced. PMID:25972465

  1. Natural water loss in selected drainage basins

    USGS Publications Warehouse

    Williams, Gordon R.

    1940-01-01

    Determinations of areal rainfall, run-off, and water loss, comprising largely evaporation from land surfaces and transpiration by vegetation, are essential in indicating the hydrologic characteristics of river basins. This report is primarily a statistical study that presents the results of computations of annual water loss, or annual rainfall minus annual run-off, for river basins in the humid or semiarid regions east of the Rocky Mountains. The basic period for which the computations are made is the water year or year ending September 30. As it is impractical to present in this report all the basic data used in arriving at the results, only sample computations are given. The various steps in the computations and the probable accuracy of the results are discussed. The drainage areas for which data are presented are those above river-measuring stations that have records for 3 years or more. For each area there are determinations of annual rainfall, annual run-off, and annual water loss for each year of record .as well as the means for the period of record. Results are given for about 200 drainage areas with an aggregate period of record of more than 2,000 years. As an illustration of the magnitude involved, the annual water loss from the eastern streams draining directly into the Atlantic Ocean varies more or less closely with latitude from about 20 inches as an average in northern New England to about 30 inches in Georgia. As the annual water loss from a basin is affected by the temperature, a supplemental study was made of the relation between water loss and temperature. For 28 drainage areas selected in various parts 8f eastern and central United States, average temperatures were computed for each year of the period shown in table 1. The results indicate a relation between average annual water loss and average annual temperature.

  2. Influence of Rotational Nucleosome Positioning on Transcription Start Site Selection in Animal Promoters

    PubMed Central

    Ambrosini, Giovanna; Bucher, Philipp

    2016-01-01

    The recruitment of RNA-Pol-II to the transcription start site (TSS) is an important step in gene regulation in all organisms. Core promoter elements (CPE) are conserved sequence motifs that guide Pol-II to the TSS by interacting with specific transcription factors (TFs). However, only a minority of animal promoters contains CPEs. It is still unknown how Pol-II selects the TSS in their absence. Here we present a comparative analysis of promoters’ sequence composition and chromatin architecture in five eukaryotic model organisms, which shows the presence of common and unique DNA-encoded features used to organize chromatin. Analysis of Pol-II initiation patterns uncovers that, in the absence of certain CPEs, there is a strong correlation between the spread of initiation and the intensity of the 10 bp periodic signal in the nearest downstream nucleosome. Moreover, promoters’ primary and secondary initiation sites show a characteristic 10 bp periodicity in the absence of CPEs. We also show that DNA natural variants in the region immediately downstream the TSS are able to affect both the nucleosome-DNA affinity and Pol-II initiation pattern. These findings support the notion that, in addition to CPEs mediated selection, sequence–induced nucleosome positioning could be a common and conserved mechanism of TSS selection in animals. PMID:27716823

  3. Perrault, Buffon and the natural history of animals

    PubMed Central

    Guerrini, Anita

    2012-01-01

    In 1733, as part of a programme to publish its early works in a uniform format, the Paris Academy of Sciences reprinted Mémoires pour servir à l'histoire naturelle des animaux (Histoire des animaux), last published in 1676, a work of both natural history and mechanistic anatomy. However, unlike the other works in this enterprise, Histoire des animaux was extensively edited and updated. In 1749 Georges-Louis Leclerc de Buffon published the first volume of Histoire naturelle. Its volumes on quadrupeds, written with Louis-Jean-Marie Daubenton, held significant similarities to Histoire des animaux. The relationship between these works has not hitherto been examined. Buffon's early ideas on species, in particular, resemble the emphasis on particulars of Histoire des animaux.

  4. Natural Selection Is a Sorting Process: What Does that Mean?

    ERIC Educational Resources Information Center

    Price, Rebecca M.

    2013-01-01

    To learn why natural selection acts only on existing variation, students categorize processes as either creative or sorting. This activity helps students confront the misconception that adaptations evolve because species need them.

  5. Natural Selection Is a Sorting Process: What Does that Mean?

    ERIC Educational Resources Information Center

    Price, Rebecca M.

    2013-01-01

    To learn why natural selection acts only on existing variation, students categorize processes as either creative or sorting. This activity helps students confront the misconception that adaptations evolve because species need them.

  6. Improvement of Endurance of DMD Animal Model Using Natural Polyphenols

    PubMed Central

    Sitzia, Clementina; Farini, Andrea; Fortunato, Francesco; Razini, Paola; Erratico, Silvia; Tavelli, Alessandro; Fabrizi, Francesco; Belicchi, Marzia; Torrente, Yvan

    2015-01-01

    Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is characterized by muscular wasting caused by dystrophin deficiency that ultimately ends in force reduction and premature death. In addition to primary genetic defect, several mechanisms contribute to DMD pathogenesis. Recently, antioxidant supplementation was shown to be effective in the treatment of multiple diseases including muscular dystrophy. Different mechanisms were hypothesized such as reduced hydroxyl radicals, nuclear factor-κB deactivation, and NO protection from inactivation. Following these promising evidences, we investigated the effect of the administration of a mix of dietary natural polyphenols (ProAbe) on dystrophic mdx mice in terms of muscular architecture and functionality. We observed a reduction of muscle fibrosis deposition and myofiber necrosis together with an amelioration of vascularization. More importantly, the recovery of the morphological features of dystrophic muscle leads to an improvement of the endurance of treated dystrophic mice. Our data confirmed that ProAbe-based diet may represent a strategy to coadjuvate the treatment of DMD. PMID:25861640

  7. Equivalence between Step Selection Functions and Biased Correlated Random Walks for Statistical Inference on Animal Movement.

    PubMed

    Duchesne, Thierry; Fortin, Daniel; Rivest, Louis-Paul

    2015-01-01

    Animal movement has a fundamental impact on population and community structure and dynamics. Biased correlated random walks (BCRW) and step selection functions (SSF) are commonly used to study movements. Because no studies have contrasted the parameters and the statistical properties of their estimators for models constructed under these two Lagrangian approaches, it remains unclear whether or not they allow for similar inference. First, we used the Weak Law of Large Numbers to demonstrate that the log-likelihood function for estimating the parameters of BCRW models can be approximated by the log-likelihood of SSFs. Second, we illustrated the link between the two approaches by fitting BCRW with maximum likelihood and with SSF to simulated movement data in virtual environments and to the trajectory of bison (Bison bison L.) trails in natural landscapes. Using simulated and empirical data, we found that the parameters of a BCRW estimated directly from maximum likelihood and by fitting an SSF were remarkably similar. Movement analysis is increasingly used as a tool for understanding the influence of landscape properties on animal distribution. In the rapidly developing field of movement ecology, management and conservation biologists must decide which method they should implement to accurately assess the determinants of animal movement. We showed that BCRW and SSF can provide similar insights into the environmental features influencing animal movements. Both techniques have advantages. BCRW has already been extended to allow for multi-state modeling. Unlike BCRW, however, SSF can be estimated using most statistical packages, it can simultaneously evaluate habitat selection and movement biases, and can easily integrate a large number of movement taxes at multiple scales. SSF thus offers a simple, yet effective, statistical technique to identify movement taxis.

  8. Equivalence between Step Selection Functions and Biased Correlated Random Walks for Statistical Inference on Animal Movement

    PubMed Central

    Duchesne, Thierry; Fortin, Daniel; Rivest, Louis-Paul

    2015-01-01

    Animal movement has a fundamental impact on population and community structure and dynamics. Biased correlated random walks (BCRW) and step selection functions (SSF) are commonly used to study movements. Because no studies have contrasted the parameters and the statistical properties of their estimators for models constructed under these two Lagrangian approaches, it remains unclear whether or not they allow for similar inference. First, we used the Weak Law of Large Numbers to demonstrate that the log-likelihood function for estimating the parameters of BCRW models can be approximated by the log-likelihood of SSFs. Second, we illustrated the link between the two approaches by fitting BCRW with maximum likelihood and with SSF to simulated movement data in virtual environments and to the trajectory of bison (Bison bison L.) trails in natural landscapes. Using simulated and empirical data, we found that the parameters of a BCRW estimated directly from maximum likelihood and by fitting an SSF were remarkably similar. Movement analysis is increasingly used as a tool for understanding the influence of landscape properties on animal distribution. In the rapidly developing field of movement ecology, management and conservation biologists must decide which method they should implement to accurately assess the determinants of animal movement. We showed that BCRW and SSF can provide similar insights into the environmental features influencing animal movements. Both techniques have advantages. BCRW has already been extended to allow for multi-state modeling. Unlike BCRW, however, SSF can be estimated using most statistical packages, it can simultaneously evaluate habitat selection and movement biases, and can easily integrate a large number of movement taxes at multiple scales. SSF thus offers a simple, yet effective, statistical technique to identify movement taxis. PMID:25898019

  9. Overcrowding and Population Growth: The Nature and Relevance of Animal Behavior.

    ERIC Educational Resources Information Center

    Stettner, Laurence J.

    This paper provides a descriptive overview of research on the consequences of overcrowding and the development of high population densities in animals, and speculates on the relevance of these studies for similar human phenomena. Three major foci are distinguished: (1) the effect of high population densities on animal behavior; (2) the nature of…

  10. Beyond genomic selection: The animal model strikes back (one generation)!

    PubMed

    Cantet, R J C; García-Baccino, C A; Rogberg-Muñoz, A; Forneris, N S; Munilla, S

    2017-06-01

    Genome inheritance is by segments of DNA rather than by independent loci. We introduce the ancestral regression (AR) as a recursive system of simultaneous equations, with grandparental path coefficients as novel parameters. The information given by the pedigree in the AR is complementary with that provided by a dense set of genomic markers, such that the resulting linear function of grandparental BV is uncorrelated to the average of parental BV in the absence of inbreeding. AR is then connected to segmental inheritance by a causal multivariate Gaussian density for BV. The resulting covariance structure (Σ) is Markovian, meaning that conditional on the BV of parents and grandparents, the BV of the animal is independent of everything else. Thus, an algorithm is presented to invert the resulting covariance structure, with a computing effort that is linear in the number of animals as in the case of the inverse additive relationship matrix. © 2017 Blackwell Verlag GmbH.

  11. Natural Selection as an Emergent Process: Instructional Implications

    ERIC Educational Resources Information Center

    Cooper, Robert A.

    2017-01-01

    Student reasoning about cases of natural selection is often plagued by errors that stem from miscategorising selection as a direct, causal process, misunderstanding the role of randomness, and from the intuitive ideas of intentionality, teleology and essentialism. The common thread throughout many of these reasoning errors is a failure to apply…

  12. Annotated selected references on natural resources investigations, Collier County, Florida

    USGS Publications Warehouse

    Swayze, L.J.

    1981-01-01

    A data base for future natural resources investigations in Collier County, Fla., was initiated by compiling a selected annotated bibliography. This report provides references and annotations for selected reports released between 1950 and 1978. The references are presented by subject material as follows: biologic, ecologic, geologic, geochemical, and hydrologic. (USGS)

  13. Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity.

    PubMed

    Bell, Rayna C; Zamudio, Kelly R

    2012-12-07

    Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

  14. Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity

    PubMed Central

    Bell, Rayna C.; Zamudio, Kelly R.

    2012-01-01

    Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism. PMID:22993253

  15. Genomic selection in domestic animals: Principles, applications and perspectives.

    PubMed

    Boichard, Didier; Ducrocq, Vincent; Croiseau, Pascal; Fritz, Sébastien

    2016-01-01

    The principles of genomic selection are described, with the main factors affecting its efficiency and the assumptions underlying the different models proposed. The reasons of its fast adoption in dairy cattle are explained and the conditions of its application to other species are discussed. Perspectives of development include: selection for new traits and new breeding objectives; adoption of more robust approaches based on information on causal variants; predictions of genotype×environment interactions.

  16. Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis

    PubMed Central

    Briggs, D. E. G.

    1999-01-01

    The nature of organic material and the environment in which it is deposited exert a major influence on the extent to which biomacromolecules are preserved in the fossil record. The role of these factors is explored with a particular focus on the cuticle of arthropods and leaves. Preservation of the original chemistry of arthropod cuticles is favoured by their thickness and degree of sclerotization, and the presence of biominerals. Decay and burial in terrestrial as opposed to marine, and anoxic rather than oxygenated conditions, likewise appear to enhance preservation. The most important factor in the long-term preservation of the chemistry of both animal and plant cuticles, however, is diagenetic alteration to an aliphatic composition. This occurs even in amber, which encapsulates the fossil, eliminating almost all external factors. Some plants contain an original decay-resistant macromolecular aliphatic component but this is not the case in arthropods. It appears that the aliphatic components of many plant as well as animal fossils may be the result of diagenetic polymerization. Selective preservation as a result of decay resistance may explain the initial survival of organic materials in sediments, but in many cases longer-term preservation relies on chemical changes. Selective preservation is only a partial explanation for the origin of kerogen.

  17. The genetic consequences of selection in natural populations.

    PubMed

    Thurman, Timothy J; Barrett, Rowan D H

    2016-04-01

    The selection coefficient, s, quantifies the strength of selection acting on a genetic variant. Despite this parameter's central importance to population genetic models, until recently we have known relatively little about the value of s in natural populations. With the development of molecular genetic techniques in the late 20th century and the sequencing technologies that followed, biologists are now able to identify genetic variants and directly relate them to organismal fitness. We reviewed the literature for published estimates of natural selection acting at the genetic level and found over 3000 estimates of selection coefficients from 79 studies. Selection coefficients were roughly exponentially distributed, suggesting that the impact of selection at the genetic level is generally weak but can occasionally be quite strong. We used both nonparametric statistics and formal random-effects meta-analysis to determine how selection varies across biological and methodological categories. Selection was stronger when measured over shorter timescales, with the mean magnitude of s greatest for studies that measured selection within a single generation. Our analyses found conflicting trends when considering how selection varies with the genetic scale (e.g., SNPs or haplotypes) at which it is measured, suggesting a need for further research. Besides these quantitative conclusions, we highlight key issues in the calculation, interpretation, and reporting of selection coefficients and provide recommendations for future research.

  18. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed Central

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L.R.

    2015-01-01

    BACKGROUND In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. METHODS A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. RESULTS AND CONCLUSIONS New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. PMID:26386468

  19. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?

    PubMed

    Sakkas, Denny; Ramalingam, Mythili; Garrido, Nicolas; Barratt, Christopher L R

    2015-01-01

    In natural conception only a few sperm cells reach the ampulla or the site of fertilization. This population is a selected group of cells since only motile cells can pass through cervical mucus and gain initial entry into the female reproductive tract. In animals, some studies indicate that the sperm selected by the reproductive tract and recovered from the uterus and the oviducts have higher fertilization rates but this is not a universal finding. Some species show less discrimination in sperm selection and abnormal sperm do arrive at the oviduct. In contrast, assisted reproductive technologies (ART) utilize a more random sperm population. In this review we contrast the journey of the spermatozoon in vivo and in vitro and discuss this in the context of developing new sperm preparation and selection techniques for ART. A review of the literature examining characteristics of the spermatozoa selected in vivo is compared with recent developments in in vitro selection and preparation methods. Contrasts and similarities are presented. New technologies are being developed to aid in the diagnosis, preparation and selection of spermatozoa in ART. To date progress has been frustrating and these methods have provided variable benefits in improving outcomes after ART. It is more likely that examining the mechanisms enforced by nature will provide valuable information in regard to sperm selection and preparation techniques in vitro. Identifying the properties of those spermatozoa which do reach the oviduct will also be important for the development of more effective tests of semen quality. In this review we examine the value of sperm selection to see how much guidance for ART can be gleaned from the natural selection processes in vivo. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.

  20. Historical evidence for nature disconnection in a 70-year time series of Disney animated films.

    PubMed

    Prévot-Julliard, Anne-Caroline; Julliard, Romain; Clayton, Susan

    2015-08-01

    The assumed ongoing disconnection between humans and nature in Western societies represents a profoundly challenging conservation issue. Here, we demonstrate one manifestation of this nature disconnection, via an examination of the representation of natural settings in a 70-year time series of Disney animated films. We found that natural settings are increasingly less present as a representation of outdoor environments in these films. Moreover, these drawn natural settings tend to be more and more human controlled and are less and less complex in terms of the biodiversity they depict. These results demonstrate the increasing nature disconnection of the filmmaking teams, which we consider as a proxy of the Western relation to nature. Additionally, because nature experience of children is partly based on movies, the depleted representation of biodiversity in outdoor environments of Disney films may amplify the current disconnection from nature for children. This reduction in exposure to nature may hinder the implementation of biodiversity conservation measures. © The Author(s) 2014.

  1. Laser surgery for selected small animal soft-tissue conditions

    NASA Astrophysics Data System (ADS)

    Bartels, Kenneth E.

    1991-05-01

    With the acquisition of a Nd:YAG and a CO2 laser in the College of Veterinary Medicine at Oklahoma State University in 1989, over 100 small animal clinical cases have been managed with these modern modalities for surgical excision and tissue vaporization. Most procedures have been for oncologic problems, but inflammatory, infectious, or congenital conditions including vaporization of acral lick 'granulomas,' excision/vaporization of foreign body induced, infected draining tracts, and resection of elongated soft palates have been successfully accomplished. Laser excision or vaporization of both benign and malignant neoplasms have effectively been performed and include feline nasal squamous cell carcinoma, mast cell tumors, and rectal/anal neoplasms. Results to date have been excellent with animals exhibiting little postoperative pain, swelling, and inflammation. Investigations involving application of laser energy for tissue welding of esophageal lacerations and hepatitic interstitial hyperthermia for metastatic colorectal cancer have also shown potential. A review of cases with an emphasis on survival time and postoperative morbidity suggests that carefully planned laser surgical procedures in clinical veterinary practice done with standardized protocols and techniques offer an acceptable means of treating conditions that were previously considered extremely difficult or virtually impossible to perform.

  2. CNTRICS final animal model task selection: Control of attention

    PubMed Central

    Lustig, C.; Kozak, R.; Sarter, M.; Young, J.W.; Robbins, T.W.

    2012-01-01

    Schizophrenia is associated with impaired attention. The top-down control of attention, defined as the ability to guide and refocus attention in accordance with internal goals and representations, was identified by the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) initiative as an important construct for task development and research. A recent CNTRICS meeting identified three tasks commonly used with rodent models as having high construct validity and promise for further development: The 5-choice serial reaction time task, the 5-choice continuous performance task, and the distractor condition sustained attention task. Here we describe their current status, including data on their neural substrates, evidence for sensitivity to neuropharmacological manipulations and genetic influences, and data from animal models of the cognitive deficits of schizophrenia. A common strength is the development of parallel human tasks to facilitate connections to the neural circuitry and drug development research done in these animal models. We conclude with recommendations for the steps needed to improve testing so that it better represents the complex biological and behavioral picture presented by schizophrenia. PMID:22683929

  3. Natural selection has driven population differentiation in modern humans.

    PubMed

    Barreiro, Luis B; Laval, Guillaume; Quach, Hélène; Patin, Etienne; Quintana-Murci, Lluís

    2008-03-01

    The considerable range of observed phenotypic variation in human populations may reflect, in part, distinctive processes of natural selection and adaptation to variable environmental conditions. Although recent genome-wide studies have identified candidate regions under selection, it is not yet clear how natural selection has shaped population differentiation. Here, we have analyzed the degree of population differentiation at 2.8 million Phase II HapMap single-nucleotide polymorphisms. We find that negative selection has globally reduced population differentiation at amino acid-altering mutations, particularly in disease-related genes. Conversely, positive selection has ensured the regional adaptation of human populations by increasing population differentiation in gene regions, primarily at nonsynonymous and 5'-UTR variants. Our analyses identify a fraction of loci that have contributed, and probably still contribute, to the morphological and disease-related phenotypic diversity of current human populations.

  4. Natural selection on functional modules, a genome-wide analysis.

    PubMed

    Serra, François; Arbiza, Leonardo; Dopazo, Joaquín; Dopazo, Hernán

    2011-03-01

    Classically, the functional consequences of natural selection over genomes have been analyzed as the compound effects of individual genes. The current paradigm for large-scale analysis of adaptation is based on the observed significant deviations of rates of individual genes from neutral evolutionary expectation. This approach, which assumed independence among genes, has not been able to identify biological functions significantly enriched in positively selected genes in individual species. Alternatively, pooling related species has enhanced the search for signatures of selection. However, grouping signatures does not allow testing for adaptive differences between species. Here we introduce the Gene-Set Selection Analysis (GSSA), a new genome-wide approach to test for evidences of natural selection on functional modules. GSSA is able to detect lineage specific evolutionary rate changes in a notable number of functional modules. For example, in nine mammal and Drosophilae genomes GSSA identifies hundreds of functional modules with significant associations to high and low rates of evolution. Many of the detected functional modules with high evolutionary rates have been previously identified as biological functions under positive selection. Notably, GSSA identifies conserved functional modules with many positively selected genes, which questions whether they are exclusively selected for fitting genomes to environmental changes. Our results agree with previous studies suggesting that adaptation requires positive selection, but not every mutation under positive selection contributes to the adaptive dynamical process of the evolution of species.

  5. Genome-wide association and genomic selection in animal breeding.

    PubMed

    Hayes, Ben; Goddard, Mike

    2010-11-01

    Results from genome-wide association studies in livestock, and humans, has lead to the conclusion that the effect of individual quantitative trait loci (QTL) on complex traits, such as yield, are likely to be small; therefore, a large number of QTL are necessary to explain genetic variation in these traits. Given this genetic architecture, gains from marker-assisted selection (MAS) programs using only a small number of DNA markers to trace a limited number of QTL is likely to be small. This has lead to the development of alternative technology for using the available dense single nucleotide polymorphism (SNP) information, called genomic selection. Genomic selection uses a genome-wide panel of dense markers so that all QTL are likely to be in linkage disequilibrium with at least one SNP. The genomic breeding values are predicted to be the sum of the effect of these SNPs across the entire genome. In dairy cattle breeding, the accuracy of genomic estimated breeding values (GEBV) that can be achieved and the fact that these are available early in life have lead to rapid adoption of the technology. Here, we discuss the design of experiments necessary to achieve accurate prediction of GEBV in future generations in terms of the number of markers necessary and the size of the reference population where marker effects are estimated. We also present a simple method for implementing genomic selection using a genomic relationship matrix. Future challenges discussed include using whole genome sequence data to improve the accuracy of genomic selection and management of inbreeding through genomic relationships.

  6. Predicting local and non-local effects of resources on animal space use using a mechanistic step selection model.

    PubMed

    Potts, Jonathan R; Bastille-Rousseau, Guillaume; Murray, Dennis L; Schaefer, James A; Lewis, Mark A

    2014-03-01

    Predicting space use patterns of animals from their interactions with the environment is fundamental for understanding the effect of habitat changes on ecosystem functioning. Recent attempts to address this problem have sought to unify resource selection analysis, where animal space use is derived from available habitat quality, and mechanistic movement models, where detailed movement processes of an animal are used to predict its emergent utilization distribution. Such models bias the animal's movement towards patches that are easily available and resource-rich, and the result is a predicted probability density at a given position being a function of the habitat quality at that position. However, in reality, the probability that an animal will use a patch of the terrain tends to be a function of the resource quality in both that patch and the surrounding habitat.We propose a mechanistic model where this non-local effect of resources naturally emerges from the local movement processes, by taking into account the relative utility of both the habitat where the animal currently resides and that of where it is moving. We give statistical techniques to parametrize the model from location data and demonstrate application of these techniques to GPS location data of caribou (Rangifer tarandus) in Newfoundland.Steady-state animal probability distributions arising from the model have complex patterns that cannot be expressed simply as a function of the local quality of the habitat. In particular, large areas of good habitat are used more intensively than smaller patches of equal quality habitat, whereas isolated patches are used less frequently. Both of these are real aspects of animal space use missing from previous mechanistic resource selection models.Whilst we focus on habitats in this study, our modelling framework can be readily used with any environmental covariates and therefore represents a unification of mechanistic modelling and step selection approaches to

  7. Predicting local and non-local effects of resources on animal space use using a mechanistic step selection model

    PubMed Central

    Potts, Jonathan R; Bastille-Rousseau, Guillaume; Murray, Dennis L; Schaefer, James A; Lewis, Mark A

    2014-01-01

    Predicting space use patterns of animals from their interactions with the environment is fundamental for understanding the effect of habitat changes on ecosystem functioning. Recent attempts to address this problem have sought to unify resource selection analysis, where animal space use is derived from available habitat quality, and mechanistic movement models, where detailed movement processes of an animal are used to predict its emergent utilization distribution. Such models bias the animal's movement towards patches that are easily available and resource-rich, and the result is a predicted probability density at a given position being a function of the habitat quality at that position. However, in reality, the probability that an animal will use a patch of the terrain tends to be a function of the resource quality in both that patch and the surrounding habitat. We propose a mechanistic model where this non-local effect of resources naturally emerges from the local movement processes, by taking into account the relative utility of both the habitat where the animal currently resides and that of where it is moving. We give statistical techniques to parametrize the model from location data and demonstrate application of these techniques to GPS location data of caribou (Rangifer tarandus) in Newfoundland. Steady-state animal probability distributions arising from the model have complex patterns that cannot be expressed simply as a function of the local quality of the habitat. In particular, large areas of good habitat are used more intensively than smaller patches of equal quality habitat, whereas isolated patches are used less frequently. Both of these are real aspects of animal space use missing from previous mechanistic resource selection models. Whilst we focus on habitats in this study, our modelling framework can be readily used with any environmental covariates and therefore represents a unification of mechanistic modelling and step selection approaches to

  8. Reducing animal sequencing redundancy by preferentially selecting animals with low-frequency haplotypes

    USDA-ARS?s Scientific Manuscript database

    Many studies leverage targeted whole genome sequencing (WGS) experiments in order to identify rare and causal variants within populations. As a natural consequence of experimental design, many of these surveys tend to sequence redundant haplotype segments due to high frequency in the base population...

  9. Natural selection reduces energy metabolism in the garden snail, helix aspersa (cornu aspersum).

    PubMed

    Artacho, Paulina; Nespolo, Roberto F

    2009-04-01

    Phenotypic selection is widely recognized as the primary cause of adaptive evolution in natural populations, a fact that has been documented frequently over the last few decades, mainly in morphological and life-history traits. The energetic definition of fitness predicts that natural selection will maximize the residual energy available for growth and reproduction, suggesting that energy metabolism could be a target of selection. To address this problem, we chose the garden snail, Helix aspersa (Cornu aspersum). We performed a seminatural experiment for measuring phenotypic selection on standard metabolic rate (SMR), the minimum cost of maintenance in ectotherm organisms. To discount selection on correlated traits, we included two additional whole-organism performance traits (mean speed and maximum force of dislodgement). We found a combination of linear (negative directional selection, beta=-0.106 +/- 0.06; P= 0.001) and quadratic (stabilizing selection, gamma=-0.012 +/- 0.033; P= 0.061) selection on SMR. Correlational selection was not significant for any possible pair of traits. This suggests that individuals with average-to-reduced SMRs were promoted by selection. To the best of our knowledge, this is the first study showing significant directional selection on the obligatory cost of maintenance in an animal, providing support for the energetic definition of fitness.

  10. Natural selection on testosterone production in a wild songbird population.

    PubMed

    McGlothlin, Joel W; Whittaker, Danielle J; Schrock, Sara E; Gerlach, Nicole M; Jawor, Jodie M; Snajdr, Eric A; Ketterson, Ellen D

    2010-06-01

    Because of their role in mediating life-history trade-offs, hormones are expected to be strongly associated with components of fitness; however, few studies have examined how natural selection acts on hormonal variation in the wild. In a songbird, the dark-eyed junco (Junco hyemalis), field experiments have shown that exogenous testosterone alters individuals' resolution of the survival-reproduction trade-off, enhancing reproduction at the expense of survival. Here we used standardized injections of gonadotropin-releasing hormone (GnRH) to assay variation in the testosterone production of males. Using measurements of annual survival and reproduction, we found evidence of strong natural selection acting on GnRH-induced increases in testosterone. Opposite to what would be predicted from the survival-reproduction trade-off, patterns of selection via survival and reproduction were remarkably similar. Males with GnRH-induced testosterone production levels that were slightly above the population mean were more likely to survive and also produced more offspring, leading to strong stabilizing selection. Partitioning reproduction into separate components revealed positive directional selection via within-pair siring success and stabilizing selection via extrapair mating success. Our data represent the most complete demonstration of natural selection on hormones via multiple fitness components, and they complement previous experiments to illuminate testosterone's role in the evolution of life-history trade-offs.

  11. Natural and sexual selection in a monogamous historical human population.

    PubMed

    Courtiol, Alexandre; Pettay, Jenni E; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

    2012-05-22

    Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760-1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species.

  12. Natural and sexual selection in a monogamous historical human population

    PubMed Central

    Courtiol, Alexandre; Pettay, Jenni E.; Jokela, Markus; Rotkirch, Anna; Lummaa, Virpi

    2012-01-01

    Whether and how human populations exposed to the agricultural revolution are still affected by Darwinian selection remains controversial among social scientists, biologists, and the general public. Although methods of studying selection in natural populations are well established, our understanding of selection in humans has been limited by the availability of suitable datasets. Here, we present a study comparing the maximum strengths of natural and sexual selection in humans that includes the effects of sex and wealth on different episodes of selection. Our dataset was compiled from church records of preindustrial Finnish populations characterized by socially imposed monogamy, and it contains a complete distribution of survival, mating, and reproductive success for 5,923 individuals born 1760–1849. Individual differences in early survival and fertility (natural selection) were responsible for most variation in fitness, even among wealthier individuals. Variance in mating success explained most of the higher variance in reproductive success in males compared with females, but mating success also influenced reproductive success in females, allowing for sexual selection to operate in both sexes. The detected opportunity for selection is in line with measurements for other species but higher than most previous reports for human samples. This disparity results from biological, demographic, economic, and social differences across populations as well as from failures by most previous studies to account for variation in fitness introduced by nonreproductive individuals. Our results emphasize that the demographic, cultural, and technological changes of the last 10,000 y did not preclude the potential for natural and sexual selection in our species. PMID:22547810

  13. Natural abundance variations in stable isotopes and their potential uses in animal physiological ecology.

    PubMed

    Gannes, L Z; Martínez del Rio, C; Koch, P

    1998-03-01

    Chemical, biological, and physical processes lead to distinctive "isotopic signatures" in biological materials that allow tracing of the origins of organic substances. Isotopic variation has been extensively used by plant physiological ecologists and by paleontologists, and recently ecologists have adopted the use of stable isotopes to measure ecosystem patterns and processes. To date, animal physiological ecologists have made minimal use of naturally occurring stable isotopes as tracers. Here we provide a review of the current and potential uses of naturally occurring stable isotopes in animal physiological ecology. We outline the physical and biological processes that lead to variation in isotopic abundance in plants and animals. We summarize current uses in animal physiological ecology (diet reconstruction and animal movement patterns), and suggest areas of research where the use of stable isotopes can be fruitful (protein balance and turnover and the allocation of dietary nutrients). We argue that animal physiological ecologists can benefit from including the measurement of naturally occurring stable isotopes in their battery of techniques. We also argue that animal physiologists can make an important contribution to the emerging field of stable isotopes in biology by testing experimentally the plethora of assumptions upon which the techniques rely.

  14. Hard and Soft Selection Revisited: How Evolution by Natural Selection Works in the Real World.

    PubMed

    Reznick, David

    2016-01-01

    The modern synthesis of evolutionary biology unified Darwin's natural selection with Mendelian genetics, but at the same time it created the dilemma of genetic load. Lewontin and Hubby's (1966) and Harris's (1966) characterization of genetic variation in natural populations increased the apparent burden of this load. Neutrality or near neutrality of genetic variation was one mechanism proposed for the revealed excessive genetic variation. Bruce Wallace coined the term "soft selection" to describe an alternative way for natural selection to operate that was consistent with observed variation. He envisioned nature as presenting ecological vacancies that could be filled by diverse genotypes. Survival and successful reproduction was a combined function of population density, genotype, and genotype frequencies, rather than a fixed value of the relative fitness of each genotype. My goal in this review is to explore the importance of soft selection in the real world. My motive and that of my colleagues as described here is not to explain what maintains genetic variation in natural populations, but rather to understand the factors that shape how organisms adapt to natural environments. We characterize how feedbacks between ecology and evolution shape both evolution and ecology. These feedbacks are mediated by density- and frequency-dependent selection, the mechanisms that underlie soft selection. Here, I report on our progress in characterizing these types of selection with a combination of a consideration of the published literature and the results from my collaborators' and my research on natural populations of guppies.

  15. Animal Detection in Natural Images: Effects of Color and Image Database

    PubMed Central

    Zhu, Weina; Drewes, Jan; Gegenfurtner, Karl R.

    2013-01-01

    The visual system has a remarkable ability to extract categorical information from complex natural scenes. In order to elucidate the role of low-level image features for the recognition of objects in natural scenes, we recorded saccadic eye movements and event-related potentials (ERPs) in two experiments, in which human subjects had to detect animals in previously unseen natural images. We used a new natural image database (ANID) that is free of some of the potential artifacts that have plagued the widely used COREL images. Color and grayscale images picked from the ANID and COREL databases were used. In all experiments, color images induced a greater N1 EEG component at earlier time points than grayscale images. We suggest that this influence of color in animal detection may be masked by later processes when measuring reation times. The ERP results of go/nogo and forced choice tasks were similar to those reported earlier. The non-animal stimuli induced bigger N1 than animal stimuli both in the COREL and ANID databases. This result indicates ultra-fast processing of animal images is possible irrespective of the particular database. With the ANID images, the difference between color and grayscale images is more pronounced than with the COREL images. The earlier use of the COREL images might have led to an underestimation of the contribution of color. Therefore, we conclude that the ANID image database is better suited for the investigation of the processing of natural scenes than other databases commonly used. PMID:24130744

  16. Nonconsumptive predator-driven mortality causes natural selection on prey.

    PubMed

    Siepielski, Adam M; Wang, Jason; Prince, Garrett

    2014-03-01

    Predators frequently exert natural selection through differential consumption of their prey. However, predators may also cause prey mortality through nonconsumptive effects, which could cause selection if different prey phenotypes are differentially susceptible to this nonconsumptive mortality. Here we present an experimental test of this hypothesis, which reveals that nonconsumptive mortality imposed by predatory dragonflies causes selection on their damselfly prey favoring increased activity levels. These results are consistent with other studies of predator-driven selection, however, they reveal that consumption alone is not the only mechanism by which predators can exert selection on prey. Uncovering this mechanism also suggests that prey defensive traits may represent adaptations to not only avoid being consumed, but also for dealing with other sources of mortality caused by predators. Demonstrating selection through both consumptive and nonconsumptive predator mortality provides us with insight into the diverse effects of predators as an evolutionary force.

  17. Human genome variability, natural selection and infectious diseases.

    PubMed

    Fumagalli, Matteo; Sironi, Manuela

    2014-10-01

    The recent availability of large-scale sequencing DNA data allowed researchers to investigate how genomic variation is distributed among populations. While demographic factors explain genome-wide population genetic diversity levels, scans for signatures of natural selection pinpointed several regions under non-neutral evolution. Recent studies found an enrichment of immune-related genes subjected to natural selection, suggesting that pathogens and infectious diseases have imposed a strong selective pressure throughout human history. Pathogen-mediated selection often targeted regulatory sites of genes belonging to the same biological pathway. Results from these studies have the potential to identify mutations that modulate infection susceptibility by integrating a population genomic approach with molecular immunology data and large-scale functional annotations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    NASA Astrophysics Data System (ADS)

    Thagard, Paul; Findlay, Scott

    2010-06-01

    Darwin’s theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin’s theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

  19. Natural selection on floral morphology can be influenced by climate.

    PubMed

    Campbell, Diane R; Powers, John M

    2015-06-07

    Climate has the potential to influence evolution, but how it influences the strength or direction of natural selection is largely unknown. We quantified the strength of selection on four floral traits of the subalpine herb Ipomopsis sp. in 10 years that differed in precipitation, causing extreme temporal variation in the date of snowmelt in the Colorado Rocky Mountains. The chosen floral traits were under selection by hummingbird and hawkmoth pollinators, with hawkmoth abundance highly variable across years. Selection for flower length showed environmental sensitivity, with stronger selection in years with later snowmelt, as higher water resources can allow translation of pollination success into fitness based on seed production. Selection on corolla width also varied across years, favouring narrower corolla tubes in two unusual years with hawkmoths, and wider corollas in another late snowmelt year. Our results illustrate how changes in climate could alter natural selection even when the primary selective agent is not directly influenced. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  20. Imperfect mimicry and the limits of natural selection.

    PubMed

    Kikuchi, David W; Pfennig, David W

    2013-12-01

    Mimicry--when one organism (the mimic) evolves a phenotypic resemblance to another (the model) due to selective benefits--is widely used to illustrate natural selection's power to generate adaptations. However, many putative mimics resemble their models imprecisely, and such imperfect mimicry represents a specific challenge to mimicry theory and a general one to evolutionary theory. Here, we discuss 11 nonmutually exclusive hypotheses for imperfect mimicry. We group these hypotheses according to whether imperfect mimicry reflects: an artifact of human perception, which is not shared by any naturally occurring predators and therefore is not truly an instance of imperfect mimicry; genetic, developmental or time-lag constraints, which (temporarily) prevent a response to selection for perfect mimicry; relaxed selection, where imperfect mimicry is as adaptive as perfect mimicry; or tradeoffs, where imperfect mimicry is (locally) more adaptive than perfect mimicry. We find that the relaxed selection hypothesis has garnered the most support. However, because only a few study systems have thus far been comprehensively evaluated, the relative contributions of the various hypotheses toward explaining the evolution of imperfect mimicry remain unclear. Ultimately, clarifying why imperfect mimicry exists should provide critical insights into the limits of natural selection in producing complex adaptations.

  1. Pairing Animal Cartoon Characters With Produce Stimulates Selection Among Child Zoo Visitors.

    PubMed

    Karpyn, Allison; Allen, Michael; Marks, Samantha; Filion, Nicole; Humphrey, Debora; Ye, Ai; May, Henry; Gardner, Meryl P

    2016-11-18

    In order to address the pervasive trend of underconsumption of fruits and vegetables among children, we examined the hypothesis that children would be more likely to select fruits (apple slices, bananas, and oranges) and vegetables (baby carrots) when paired with animal cartoon image than when available without the character image. Tested in a randomized experiment using counterbalancing, products were arranged on two tables at two separate family fun nights held at a local zoo. Animal character produce parings were manipulated by placing one of two animals (tamarin or iguana) next to two of the four fruit or vegetable selections at each table, and by changing when available without the image. In total, 755 produce selections were made. Significantly more products paired with a character were selected (62.38%) than the same products, not paired (37.62%), χ(2) = 46.32, df = 1, p < .001. The odds ratio of the treatment versus control was 1.66 (i.e., 471/284), indicating that children were 66% more likely to select a snack when paired with an animal cartoon. Study findings highlight the positive impact of animal cartoons on children's fruit and vegetable snack selections, and results suggest the potential for using animal cartoons to encourage fruit and vegetable selection for children.

  2. A review of experimental and natural infections of animals with monkeypox virus between 1958 and 2012

    PubMed Central

    Parker, Scott; Buller, R Mark

    2013-01-01

    Monkeypox virus (MPXV) was discovered in 1958 during an outbreak in an animal facility in Copenhagen, Denmark. Since its discovery, MPXV has revealed a propensity to infect and induce disease in a large number of animals within the mammalia class from pan-geographical locations. This finding has impeded the elucidation of the natural host, although the strongest candidates are African squirrels and/or other rodents. Experimentally, MPXV can infect animals via a variety of multiple different inoculation routes; however, the natural route of transmission is unknown and is likely to be somewhat species specific. In this review we have attempted to compile and discuss all published articles that describe experimental or natural infections with MPXV, dating from the initial discovery of the virus through to the year 2012. We further discuss the comparative disease courses and pathologies of the host species. PMID:23626656

  3. Constraint, natural selection, and the evolution of human body form.

    PubMed

    Savell, Kristen R R; Auerbach, Benjamin M; Roseman, Charles C

    2016-08-23

    Variation in body form among human groups is structured by a blend of natural selection driven by local climatic conditions and random genetic drift. However, attempts to test ecogeographic hypotheses have not distinguished between adaptive traits (i.e., those that evolved as a result of selection) and those that evolved as a correlated response to selection on other traits (i.e., nonadaptive traits), complicating our understanding of the relationship between climate and morphological distinctions among populations. Here, we use evolutionary quantitative methods to test if traits previously identified as supporting ecogeographic hypotheses were actually adaptive by estimating the force of selection on individual traits needed to drive among-group differentiation. Our results show that not all associations between trait means and latitude were caused by selection acting directly on each individual trait. Although radial and tibial length and biiliac and femoral head breadth show signs of responses to directional selection matching ecogeographic hypotheses, the femur was subject to little or no directional selection despite having shorter values by latitude. Additionally, in contradiction to ecogeographic hypotheses, the humerus was under directional selection for longer values by latitude. Responses to directional selection in the tibia and radius induced a nonadaptive correlated response in the humerus that overwhelmed its own trait-specific response to selection. This result emphasizes that mean differences between groups are not good indicators of which traits are adaptations in the absence of information about covariation among characteristics.

  4. Hidden evolution: progress and limitations in detecting multifarious natural selection.

    PubMed

    Johnson, Norman A; Kliman, Richard M

    2002-04-01

    From illustrative examples of research on the best-studied group of species to date, Drosophila melanogaster and its closest relatives, we argue that selection is multifarious, but often hidden. Selective fixation of new, highly advantageous alleles is the most parsimonious explanation for a typical pattern of molecular variation observed in genomic regions characterized by very low recombination: drastically reduced DNA sequence variation within species and typical levels of sequence divergence among species. At the same time, the identity of the gene (or genes) influenced by selection is not just difficult to discern; it may be impossible. Studies of the genetic basis of reproductive isolation demonstrate that, although the D. melanogaster complex species appear virtually identical, dozens of currently unidentified genes contribute to hybrid sterility. We argue that these findings are best explained by selectively-driven functional divergence and demonstrate the multifarious nature of selection. Although multifarious selection certainly occurs, the exact characters responsible for differences in survival and reproductive success are unknown. We do not see these inherent limits as a cause for despair or a problem for evolutionary biology. Instead, we hope to raise awareness of these complexities of evolution by highlighting both the progress and the limitations of characterizing multifarious natural selection.

  5. Antiherbivore defenses alter natural selection on plant reproductive traits.

    PubMed

    Thompson, Ken A; Johnson, Marc T J

    2016-04-01

    While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether antiherbivore defenses affect selection on these traits. We hypothesized that antiherbivore defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent antiherbivore defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and antiherbivore defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how antiherbivore defenses interact with herbivores and pollinators to shape floral evolution.

  6. Natural selection and genital variation: a role for the environment, parasites and sperm ageing?

    PubMed

    Reinhardt, Klaus

    2010-01-01

    Male genitalia are more variable between species (and populations) than other organs, and are more morphologically complex in polygamous compared to monogamous species. Therefore, sexual selection has been put forward as the major explanation of genital variation and complexity, in particular cryptic female choice for male copulatory courtship. As cryptic female choice is based on differences between males it is somewhat paradoxical that there is such low within-species variation in male genitalia that they are a prime morphological identification character for animal species. Processes other than sexual selection may also lead to genitalia variation but they have recently become neglected. Here I focus on pleiotropy and natural selection and provide examples how they link genitalia morphology with genital environments. Pleiotropy appears to be important because most studies that specifically tested for pleiotropic effects on genital morphology found them. Natural selection likely favours certain genital morphology over others in various environments, as well as by reducing re-infection with sexually transmitted diseases or reducing the likelihood of fertilisation with aged sperm. Both pleiotropy and natural selection differ locally and between species so may contribute to local variation in genitalia and sometimes variation between monogamous and polygamous species. Furthermore, the multitude of genital environments will lead to a multitude of genital functions via natural selection and pleiotropy, and may also contribute to explaining the complexity of genitalia.

  7. Natural Selection VS. Random Drift: Evidence from Temporal Variation in Allele Frequencies in Nature

    PubMed Central

    Mueller, Laurence D.; Barr, Lorraine G.; Ayala, Francisco J.

    1985-01-01

    We have obtained monthly samples of two species, Drosophila pseudoobscura and Drosophila persimilis, in a natural population from Napa County, California. In each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from March 1972 to June 1975. Using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. The methods used do not detect natural selection when it is deterministic (e.g., overdominance or directional selection), but only when alleles at different loci vary simultaneously in response to the same environmental variations. Moreover, only relatively large fitness differences (of the order of 15%) are detectable. We have found strong evidence of correlated allele frequency variation in 13–20% of the cases examined. We interpret this as evidence that natural selection plays a major role in the evolution of protein polymorphisms in nature. PMID:4054608

  8. Using Different Examples of Natural Selection When Teaching Biology.

    ERIC Educational Resources Information Center

    Perry, Robert T.

    1993-01-01

    Describes the following examples of natural selection for use in science instruction: sickle-cell anemia and human beings, clogged crabs, the rounding of the human head, shell color in land snails, pollinator behavior and flower color, copper tolerance in a grass, lizards and quick change, and Darwin's finches. (PR)

  9. The Living Dead: Transformative Experiences in Modelling Natural Selection

    ERIC Educational Resources Information Center

    Petersen, Morten Rask

    2017-01-01

    This study considers how students change their coherent conceptual understanding of natural selection through a hands-on simulation. The results show that most students change their understanding. In addition, some students also underwent a transformative experience and used their new knowledge in a leisure time activity. These transformative…

  10. Selection criteria for forested natural areas in New England, USA

    Treesearch

    William B. Leak; Mariko Yamasaki; Marie-Louise Smith; David T. Funk

    1994-01-01

    The selection of forested natural areas for research and educational purposes is discussed. Five factors are important: sufficient size; representation of typical communities and sites; documented disturbance histories; acceptable current condition in terms of age, tree size, and successional stage; and administrative feasibility.

  11. The Nature of Selected English Teachers' Online Participation

    ERIC Educational Resources Information Center

    Rodesiler, Luke

    2015-01-01

    This article documents an investigation into the nature of selected secondary English teachers' online participation across platforms (i.e., blogs, microblogs, social networking sites) as they explored issues related to teaching, learning, and literacy. Ethnographic content analysis of online artifacts generated over approximately 10 months…

  12. Reconsidering the logical structure of the theory of natural selection

    PubMed Central

    Hunt, Tam

    2014-01-01

    Natural selection has been criticized as a tautology. This would be a major problem for evolutionary biology, if true, because tautological statements can't be falsified and, therefore, can't be scientific. There is merit to this critique insofar as the theory of natural selection is indeed generally described in a tautological manner. However, natural selection can be described non-tautologically if we’re careful. Natural selection should be defined as the theory that attempts to predict and retrodict evolutionary change through environmental forces acting upon organisms. However, this re-framing comes at a cost: it reveals, based on our current knowledge of evolutionary forces, the lack of ability to make accurate predictions about expected changes except in the most simple of circumstances. I suggest that evolutionary biologists should work to develop “principles of evolution,” based on an expanded and more focused research program designed to identify common trends in evolution, which will ultimately allow us to make more accurate predictions and retrodictions about evolution. PMID:26478764

  13. The Nature of Selected English Teachers' Online Participation

    ERIC Educational Resources Information Center

    Rodesiler, Luke

    2015-01-01

    This article documents an investigation into the nature of selected secondary English teachers' online participation across platforms (i.e., blogs, microblogs, social networking sites) as they explored issues related to teaching, learning, and literacy. Ethnographic content analysis of online artifacts generated over approximately 10 months…

  14. Using Different Examples of Natural Selection When Teaching Biology.

    ERIC Educational Resources Information Center

    Perry, Robert T.

    1993-01-01

    Describes the following examples of natural selection for use in science instruction: sickle-cell anemia and human beings, clogged crabs, the rounding of the human head, shell color in land snails, pollinator behavior and flower color, copper tolerance in a grass, lizards and quick change, and Darwin's finches. (PR)

  15. Optimizing Selection of Large Animals for Antibody Production by Screening Immune Response to Standard Vaccines

    PubMed Central

    Thompson, Mary K.; Fridy, Peter C.; Keegan, Sarah; Chait, Brian T.; Fenyö, David; Rout, Michael P.

    2016-01-01

    Antibodies made in large animals are integral to many biomedical research endeavors. Domesticated herd animals like goats, sheep, donkeys, horses and camelids all offer distinct advantages in antibody production. However, their cost of use is often prohibitive, especially where poor antigen response is commonplace; choosing a non-responsive animal can set a research program back or even prevent experiments from moving forward entirely. Over the course of production of antibodies from llamas, we found that some animals consistently produced a higher humoral antibody response than others, even to highly divergent antigens, as well as to their standard vaccines. Based on our initial data, we propose that these “high level responders” could be pre-selected by checking antibody titers against common vaccines given to domestic farm animals. Thus, time and money can be saved by reducing the chances of getting poor responding animals and minimizing the use of superfluous animals. PMID:26775851

  16. Optimizing selection of large animals for antibody production by screening immune response to standard vaccines.

    PubMed

    Thompson, Mary K; Fridy, Peter C; Keegan, Sarah; Chait, Brian T; Fenyö, David; Rout, Michael P

    2016-03-01

    Antibodies made in large animals are integral to many biomedical research endeavors. Domesticated herd animals like goats, sheep, donkeys, horses and camelids all offer distinct advantages in antibody production. However, their cost of use is often prohibitive, especially where poor antigen response is commonplace; choosing a non-responsive animal can set a research program back or even prevent experiments from moving forward entirely. Over the course of production of antibodies from llamas, we found that some animals consistently produced a higher humoral antibody response than others, even to highly divergent antigens, as well as to their standard vaccines. Based on our initial data, we propose that these "high level responders" could be pre-selected by checking antibody titers against common vaccines given to domestic farm animals. Thus, time and money can be saved by reducing the chances of getting poor responding animals and minimizing the use of superfluous animals. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Secrets and lies: "selective openness" in the apparatus of animal experimentation.

    PubMed

    Holmberg, Tora; Ideland, Malin

    2012-04-01

    Researchers and other (human) actors within the apparatus of animal experimentation find themselves in a tight corner. They rely on public acceptance to promote their legitimacy and to receive funding. At the same time, those working with animal experimentation take risks by going public, fearing that the public will misunderstand their work and animal rights activists may threaten them. The dilemma that emerges between openness and secrecy is fairly prevalent in scientific culture as a whole, but the apparatus of animal experimentation presents specific patterns of technologies of secrets. The aim of the paper is to describe and analyse the meanings of secrets and openness in contemporary animal experimentation. We suggest that these secrets--or "selective openness"--can be viewed as grease in the apparatus of animal experimentation, as a unifying ingredient that permits maintenance of status quo in human/animal relations and preserves existing institutional public/ science relations.

  18. Natural selection on floral volatile production in Penstemon digitalis

    PubMed Central

    Parachnowitsch, Amy L.; Burdon, Rosalie C. F.; Raguso, Robert A.; Kessler, André

    2013-01-01

    Natural selection is thought to have shaped the evolution of floral scent; however, unlike other floral characters, we have a rudimentary knowledge of how phenotypic selection acts on scent. We found that floral scent was under stronger selection than corolla traits such as flower size and flower color in weakly scented Penstemon digitalis. Our results suggest that to understand evolution in floral phenotypes, including scent in floral selection, studies are crucial. For P. digitalis, linalool was the direct target of selection in the scent bouquet. Therefore, we determined the enantiomeric configuration of linalool because interacting insects may perceive the enantiomers differentially. We found that P. digitalis produces only (S)-(+)-linalool and, more interestingly, it is also taken up into the nectar. Because the nectar is scented and flavored with (S)-(+)-linalool, it may be an important cue for pollinators visiting P. digitalis flowers. PMID:23221753

  19. When natural selection gives gene function the cold shoulder.

    PubMed

    Cutter, Asher D; Jovelin, Richard

    2015-11-01

    It is tempting to invoke organismal selection as perpetually optimizing the function of any given gene. However, natural selection can drive genic functional change without improvement of biochemical activity, even to the extinction of gene activity. Detrimental mutations can creep in owing to linkage with other selectively favored loci. Selection can promote functional degradation, irrespective of genetic drift, when adaptation occurs by loss of gene function. Even stabilizing selection on a trait can lead to divergence of the underlying molecular constituents. Selfish genetic elements can also proliferate independent of any functional benefits to the host genome. Here we review the logic and evidence for these diverse processes acting in genome evolution. This collection of distinct evolutionary phenomena - while operating through easily understandable mechanisms - all contribute to the seemingly counterintuitive notion that maintenance or improvement of a gene's biochemical function sometimes do not determine its evolutionary fate.

  20. Natural selection on immune responsiveness in blue tits Parus caeruleus.

    PubMed

    Råberg, Lars; Stjernman, Martin

    2003-07-01

    What is the form of natural selection on immune responsiveness? For a population at evolutionary equilibrium, there are two different scenarios. First, it is generally assumed that immune defense has both benefits and costs. If variation in immune responsiveness is due to variation in how individuals trade off these costs and benefits, one would expect immune responsiveness to be subject to stabilizing selection. Second, it is well known that an individual's immune responsiveness is often dependent on its overall condition. If immune responsiveness is condition-dependent, one would expect immune responsiveness to be under positive directional selection. We would therefore expect that the form of natural selection on immune responsiveness depends on the relative magnitude of these two sources of variation: variation in how individuals trade off the costs and benefits of defense, and variation in condition. We measured primary and secondary antibody responsiveness to diphtheria-tetanus vaccine in blue tits during winter and investigated the relationship between responsiveness and survival to the following breeding season. We use responsiveness to these antigens as measures of an individual's ability or propensity to mount an antibody response in case of an infection. Interestingly, different measures of responsiveness were subject to different selective regimes: primary responsiveness to diphtheria was subject to stabilizing selection, whereas secondary responsiveness to tetanus was subject to positive directional selection. In contrast, there was no significant selection on primary responsiveness to tetanus or secondary responsiveness to diphtheria. The finding of stabilizing selection on a measure of responsiveness is evidence that immune defense can incur fitness costs; a central but little-tested assumption of theories of the ecology and evolution of immunological defense. The finding of directional selection on a measure of responsiveness is consistent with the

  1. Rescuing valuable genomes by animal cloning: a case for natural disease resistance in cattle.

    PubMed

    Westhusin, M E; Shin, T; Templeton, J W; Burghardt, R C; Adams, L G

    2007-01-01

    Tissue banking and animal cloning represent a powerful tool for conserving and regenerating valuable animal genomes. Here we report an example involving cattle and the rescue of a genome affording natural disease resistance. During the course of a 2-decade study involving the phenotypic and genotypic analysis for the functional and genetic basis of natural disease resistance against bovine brucellosis, a foundation sire was identified and confirmed to be genetically resistant to Brucella abortus. This unique animal was utilized extensively in numerous animal breeding studies to further characterize the genetic basis for natural disease resistance. The bull died in 1996 of natural causes, and no semen was available for AI, resulting in the loss of this valuable genome. Fibroblast cell lines had been established in 1985, cryopreserved, and stored in liquid nitrogen for future genetic analysis. Therefore, we decided to utilize these cells for somatic cell nuclear transfer to attempt the production of a cloned bull and salvage this valuable genotype. Embryos were produced by somatic cell nuclear transfer and transferred to 20 recipient cows, 10 of which became pregnant as determined by ultrasound at d 40 of gestation. One calf survived to term. At present, the cloned bull is 4.5 yr old and appears completely normal as determined by physical examination and blood chemistry. Furthermore, in vitro assays performed to date indicate this bull is naturally resistant to B. abortus, Mycobacterium bovis, and Salmonella typhimurium, as was the original genetic donor.

  2. The Divergence and Natural Selection of Autocatalytic Primordial Metabolic Systems

    NASA Astrophysics Data System (ADS)

    Marakushev, Sergey A.; Belonogova, Ol'ga V.

    2013-06-01

    The diversity of the central metabolism of modern organisms is caused by the existence of a few metabolic modules, combination of which produces multiple metabolic pathways. This paper analyzes biomimetically reconstructed coupled autocatalytic cycles as the basis of ancestral metabolic systems. The mechanism for natural selection and evolution in autocatalytic chemical systems may be affected by natural homeostatic parameters such as ambient chemical potentials, temperature, and pressure. Competition between separate parts of an autocatalytic network with positive-plus-negative feedback resulted in the formation of primordial autotrophic, mixotrophic, and heterotrophic metabolic systems. This work examined the last common ancestor of a set of coupled metabolic cycles in a population of protocells. Physical-chemical properties of these cycles determined the main principles of natural selection for the ancestral Bacteria and Archaea taxa.

  3. Learning natural selection from the site frequency spectrum.

    PubMed

    Ronen, Roy; Udpa, Nitin; Halperin, Eran; Bafna, Vineet

    2013-09-01

    Genetic adaptation to external stimuli occurs through the combined action of mutation and selection. A central problem in genetics is to identify loci responsive to specific selective constraints. Many tests have been proposed to identify the genomic signatures of natural selection by quantifying the skew in the site frequency spectrum (SFS) under selection relative to neutrality. We build upon recent work that connects many of these tests under a common framework, by describing how selective sweeps affect the scaled SFS. We show that the specific skew depends on many attributes of the sweep, including the selection coefficient and the time under selection. Using supervised learning on extensive simulated data, we characterize the features of the scaled SFS that best separate different types of selective sweeps from neutrality. We develop a test, SFselect, that consistently outperforms many existing tests over a wide range of selective sweeps. We apply SFselect to polymorphism data from a laboratory evolution experiment of Drosophila melanogaster adapted to hypoxia and identify loci that strengthen the role of the Notch pathway in hypoxia tolerance, but were missed by previous approaches. We further apply our test to human data and identify regions that are in agreement with earlier studies, as well as many novel regions.

  4. Natural selection on immune defense: A field experiment.

    PubMed

    Langeloh, Laura; Behrmann-Godel, Jasminca; Seppälä, Otto

    2017-02-01

    Predicting the evolution of phenotypic traits requires an understanding of natural selection on them. Despite its indispensability in the fight against parasites, selection on host immune defense has remained understudied. Theory predicts immune traits to be under stabilizing selection due to associated trade-offs with other fitness-related traits. Empirical studies, however, report mainly positive directional selection. This discrepancy could be caused by low phenotypic variation in the examined individuals and/or variation in host resource level that confounds trade-offs in empirical studies. In a field experiment where we maintained Lymnaea stagnalis snails individually in cages in a lake, we investigated phenotypic selection on two immune defense traits, phenoloxidase (PO)-like activity and antibacterial activity, in hemolymph. We used a diverse laboratory population and manipulated snail resource level by limiting their food supply. For six weeks, we followed immune activity, growth, and two fitness components, survival and fecundity of snails. We found that PO-like activity and growth were under stabilizing selection, while antibacterial activity was under positive directional selection. Selection on immune traits was mainly driven by variation in survival. The form of selection on immune defense apparently depends on the particular trait, possibly due to its importance for countering the present parasite community. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  5. Coalition formation in animals and the nature of winner and loser effects.

    PubMed Central

    Johnstone, R A; Dugatkin, L A

    2000-01-01

    Coalition formation has been documented in a diverse array of taxa, yet there has been little formal analysis of polyadic interactions such as coalitions. Here, we develop an optimality model which examines the role of winner and loser effects in shaping coalition formation. We demonstrate that the predicted patterns of alliances are strongly dependent on the way in which winner and loser effects change with contestant strength. When winner and loser effects decrease with the resource-holding power (RHP) of the combatants, coalitions will be favoured between the strongest members of a group, but not between the weakest. If, in contrast, winner and loser effects increase with RHP, exactly the opposite predictions emerge. All other things being equal, intervention is more likely to prove worthwhile when the beneficiary of the aid is weaker (and its opponent is stronger), because the beneficiary is then less likely to win without help. Consequently, intervention is more probable when the impact of victory on the subsequent performance of a combatant increases with that individual's strength because this selects for intervention in favour of weaker combatants. The published literature on hierarchy formation does not reveal how winner and loser effects actually change with contestant strength and we therefore hope that our model will spur others to collect such data; in this light we suggest an experiment which will help to elucidate the nature of winner and loser effects and their impact on coalition formation in animals. PMID:10670947

  6. The insufficient part of abiogenesis theory - natural selection

    NASA Astrophysics Data System (ADS)

    Ploompuu, Tõnu

    2016-04-01

    Abiogenesis has already been studied for a whole century. There have been studies on the synthesis of precursors of biopolymers, concentration processes and polymerization pathways, sites of initiation of life. Autoreplication has been explained. Protocells have been constructed from abiogenic membranes. But one essential aspect for life - the natural selection - has been marginalized in these investigations. Despite the convincing use of natural selection in biology for one and half century, it has not been used sufficiently in the models of the beginning of life. Pictorially - Darwin's pond model is used without darwinism. This generates an unnecessary interruption on the path for understanding the process. Natural selection is essential in abiogenesis, in the genesis of biological information system. A selection of more collaborative autoreplicate biopolymers and the depolymerisation of others was required. Only natural selection was able to combine biopolymer molecules for life. The primary natural selection can operate only in an environment with variable physical and chemical conditions. The selective agent must constantly fluctuate during a long time span and a large area. Formation of the simplest complex of life needs homeostasis. The best sites for constant fluctuations are littoral areas of oceans. Two very constant fluctuations - waves and tides - occur there. The best conditions for the origin of life were exactly in the end of the Late Heavy Bombardment at temperature nealy 100° C. Earth's surface was then protected against the UV destruction by a thick cloud cover. High evaporation at the hotter parts of shore rocks increased the concentration of the primordial soup and there was excellent selective power by routine water level fluctuations. Because of the water level fluctuations salty ocean water and fresh water from continuous downpours alternated at the littoral zones. In low temperatures the formation of life would be hindered by UV

  7. Fisher's fundamental theorem of inclusive fitness and the change in fitness due to natural selection when conspecifics interact.

    PubMed

    Bijma, P

    2010-01-01

    Competition and cooperation is fundamental to evolution by natural selection, both in animals and plants. Here, I investigate the consequences of such interactions for response in fitness due to natural selection. I provide quantitative genetic expressions for heritable variance and response in fitness due to natural selection when conspecifics interact. Results show that interactions among conspecifics generate extra heritable variance in fitness, and that interacting with kin is the key to evolutionary success because it translates the extra heritable variance into response in fitness. This work also unifies Fisher's fundamental theorem of natural selection (FTNS) and Hamilton's inclusive fitness (IF). The FTNS implies that natural selection maximizes fitness, whereas Hamilton proposed maximization of IF. This work shows that the FTNS describes the increase in IF, rather than direct fitness, at a rate equal to the additive genetic variance in fitness. Thus, Hamilton's IF and Fisher's FTNS both describe the maximization of IF.

  8. Differential responses to distinct psychotropic agents of selectively bred dominant and submissive animals.

    PubMed

    Nesher, Elimelech; Gross, Moshe; Lisson, Serah; Tikhonov, Tatiana; Yadid, Gal; Pinhasov, Albert

    2013-01-01

    Dominance and submissiveness are two opposite poles of behavior representing important functional elements in the development of social interactions. We previously demonstrated the inheritability of these traits by selective breeding based upon the dominant-submissive relationships (DSR) food competition paradigm. Continued multigenerational behavioral selection of Sabra mice yielded animal populations with strong and stable features of dominance and submissiveness. We found that these animals react differentially to stressogenic triggers, antidepressants and mood stabilizing agents. The anxiolytic compound diazepam (1.5mg/kg, i.p.) reduced anxiety-like behavior of submissive animals, but showed anxiogenic effects among dominant animals. In the Forced Swim test, the antidepressant paroxetine (1, 3 and 10mg/kg, i.p.) markedly reduced immobility of submissive animals, demonstrating antidepressant-like effect. In contrast, when administered to dominant animals, paroxetine caused extreme (frenetic) activity. The mood stabilizer lithium (0.4%, p.o.) selectively influenced dominant mice, without affecting the behavior of submissive animals. In summary, we describe here two distinct animal populations possessing strong dominant and submissive phenotypes. We suggest that these populations hold potential as tools for studying the molecular basis and pharmacogenetics of dominant and submissive behavior. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Darwin and his pigeons. The analogy between artificial and natural selection revisited.

    PubMed

    Theunissen, Bert

    2012-01-01

    The analogy between artificial selection of domestic varieties and natural selection in nature was a vital element of Darwin's argument in his Origin of Species. Ever since, the image of breeders creating new varieties by artificial selection has served as a convincing illustration of how the theory works. In this paper I argue that we need to reconsider our understanding of Darwin's analogy. Contrary to what is often assumed, nineteenth-century animal breeding practices constituted a highly controversial field that was fraught with difficulties. It was only with considerable effort that Darwin forged his analogy, and he only succeeded by downplaying the importance of two other breeding techniques - crossing of varieties and inbreeding - that many breeders deemed essential to obtain new varieties. Part of the explanation for Darwin's gloss on breeding practices, I shall argue, was that the methods of his main informants, the breeders of fancy pigeons, were not representative of what went on in the breeding world at large. Darwin seems to have been eager to take the pigeon fanciers at their word, however, as it was only their methods that provided him with the perfect analogy with natural selection. Thus while his studies of domestic varieties were important for the development of the concept of natural selection, the reverse was also true: Darwin's comprehension of breeding practices was moulded by his understanding of the working of natural selection in nature. Historical studies of domestic breeding practices in the eighteenth and nineteenth century confirm that, besides selection, the techniques of inbreeding and crossing were much more important than Darwin's interpretation allowed for. And they still are today. This calls for a reconsideration of the pedagogic use of Darwin's analogy too.

  10. Assortment and the analysis of natural selection on social traits.

    PubMed

    McDonald, Grant C; Farine, Damien R; Foster, Kevin R; Biernaskie, Jay M

    2017-09-08

    A central problem in evolutionary biology is to determine whether and how social interactions contribute to natural selection. This can be addressed with selection analyses that relate individual fitness to individual and social phenotypes. One such approach, known as social selection analysis, leads to the intuitive result that fitness effects from social partners will contribute to selection only if there is a correlation between the traits of individuals and their social partners (non-random phenotypic assortment). However, there have been inconsistencies in the application of this approach that center around the measurement of phenotypic assortment. Here, we use data analysis and simulations to resolve these inconsistencies, showing that: (i) not all measures of assortment are suitable for social selection analysis; and (ii) the interpretation of assortment, and how to detect non-random assortment, will depend on the scale at which it is measured. We discuss links between social selection and kin selection theory, and we provide a practical guide for the social selection approach. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  11. Elementary Students' Investigations in Natural Selection

    ERIC Educational Resources Information Center

    Bartley, Nancy; Concannon, James P.; Brown, Patrick L.

    2014-01-01

    Students love learning about animals: how animals behave, what animals eat, why some animals are more dangerous than others are, and why animals look the way they do. In this 5E lesson, students investigate why some animals look the way they do--specifically, the advantages of camouflage and mimicry. What are an animal's advantages of being…

  12. Elementary Students' Investigations in Natural Selection

    ERIC Educational Resources Information Center

    Bartley, Nancy; Concannon, James P.; Brown, Patrick L.

    2014-01-01

    Students love learning about animals: how animals behave, what animals eat, why some animals are more dangerous than others are, and why animals look the way they do. In this 5E lesson, students investigate why some animals look the way they do--specifically, the advantages of camouflage and mimicry. What are an animal's advantages of being…

  13. Natural selection on plant physiological traits in an urban environment

    NASA Astrophysics Data System (ADS)

    Lambrecht, Susan C.; Mahieu, Stephanie; Cheptou, Pierre-Olivier

    2016-11-01

    Current rates of urbanization are creating new opportunities for studying urban plant ecology, but our knowledge of urban plant physiology lags behind that of other ecosystems. Moreover, higher temperatures, elevated CO2, and increased inorganic nitrogen deposition along with altered moisture regimes of urban as compared to rural areas creates a compelling analog for studying adaptations of plants to climate change. We grew plants under common conditions in a greenhouse to determine whether populations of Crepis sancta (Asteraceae) differed in phenological, morphological, and physiological traits. We also used a field experiment to test for natural selection on these traits in urban Montpellier, France. Urban plants flowered and senesced later than rural plants, and natural selection favored later phenology in the urban habitat. Natural selection also favored larger plants with more leaves, and increased photosynthesis and leaf nitrogen concentration. Ours is the first study to document selection on plant functional traits in an urban habitat and, as such, advances our understanding of urban plant ecology and possible adaptations to climate change.

  14. Of Animals, Nature and People. Teacher's Guide. Preparing for Tomorrow's World.

    ERIC Educational Resources Information Center

    Iozzi, Louis A.; And Others

    "Of Animals, Nature and People" is one of the "Preparing for Tomorrow's World" (PTW) program modules. PTW is an interdisciplinary, future-oriented program incorporating information from the sciences and social sciences and addressing societal concerns which interface science/technology/society. The program promotes responsible…

  15. Of Animals, Nature and People. [Student's Guide.] Preparing for Tomorrow's World.

    ERIC Educational Resources Information Center

    Iozzi, Louis A.; And Others

    Developing an awareness of the need to evolve an environmental ethic is the intent of this module, designed for the senior high school level (grades 10-11). The module is divided into two sections. Section 1 contains a series of dilemma/discussion activities raising issues regarding human behavior toward animals and the natural environment.…

  16. [Live Animals and Staged Nature : Drawing and Photography in German Popular Zoology between 1860 and 1910].

    PubMed

    Gall, Alexander

    2017-06-01

    It is the central thesis of this paper that the "biological perspective" (Lynn Nyhart) typical for Germany, with its interest in living animals, not only influenced natural history practices in many ways during the second half of the 19th century, rather also shaped the illustrations of popular zoology publications, as for example those in Brehms Thierleben. The illustrators of this period preferred to use live animals as models, which they studied in zoos. These animals were often depicted in their "natural" habitats. Since the illustrators knew only very little about these habitats, they had to be imagined. Another fashionable genre within popular zoology was the portrayal of animals fighting, which attracted attention because of their drama. The first wildlife photographers oriented themselves on the zoological illustrations and, with the aid of manipulation, staging and retouching, gave their photographs the impression of natural surroundings and drama. Yet both the illustrators and the photographers emphasized their truth to nature and - based on this - the scientific value of their pictures. In so doing, they developed a "biological" kind of wildlife photography, which, after the turn of the 19th century, allowed dedicated amateurs to create a popular zoological oeuvre that was well received by broad audiences.

  17. Animator

    ERIC Educational Resources Information Center

    Tech Directions, 2008

    2008-01-01

    Art and animation work is the most significant part of electronic game development, but is also found in television commercials, computer programs, the Internet, comic books, and in just about every visual media imaginable. It is the part of the project that makes an abstract design idea concrete and visible. Animators create the motion of life in…

  18. Animator

    ERIC Educational Resources Information Center

    Tech Directions, 2008

    2008-01-01

    Art and animation work is the most significant part of electronic game development, but is also found in television commercials, computer programs, the Internet, comic books, and in just about every visual media imaginable. It is the part of the project that makes an abstract design idea concrete and visible. Animators create the motion of life in…

  19. Naturally selecting solutions: the use of genetic algorithms in bioinformatics.

    PubMed

    Manning, Timmy; Sleator, Roy D; Walsh, Paul

    2013-01-01

    For decades, computer scientists have looked to nature for biologically inspired solutions to computational problems; ranging from robotic control to scheduling optimization. Paradoxically, as we move deeper into the post-genomics era, the reverse is occurring, as biologists and bioinformaticians look to computational techniques, to solve a variety of biological problems. One of the most common biologically inspired techniques are genetic algorithms (GAs), which take the Darwinian concept of natural selection as the driving force behind systems for solving real world problems, including those in the bioinformatics domain. Herein, we provide an overview of genetic algorithms and survey some of the most recent applications of this approach to bioinformatics based problems.

  20. Colloquium papers: Natural selection in a contemporary human population.

    PubMed

    Byars, Sean G; Ewbank, Douglas; Govindaraju, Diddahally R; Stearns, Stephen C

    2010-01-26

    Our aims were to demonstrate that natural selection is operating on contemporary humans, predict future evolutionary change for specific traits with medical significance, and show that for some traits we can make short-term predictions about our future evolution. To do so, we measured the strength of selection, estimated genetic variation and covariation, and predicted the response to selection for women in the Framingham Heart Study, a project of the National Heart, Lung, and Blood Institute and Boston University that began in 1948. We found that natural selection is acting to cause slow, gradual evolutionary change. The descendants of these women are predicted to be on average slightly shorter and stouter, to have lower total cholesterol levels and systolic blood pressure, to have their first child earlier, and to reach menopause later than they would in the absence of evolution. Selection is tending to lengthen the reproductive period at both ends. To better understand and predict such changes, the design of planned large, long-term, multicohort studies should include input from evolutionary biologists.

  1. Genetic signatures of natural selection in a model invasive ascidian

    PubMed Central

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-01-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta. PMID:28266616

  2. Genetic signatures of natural selection in a model invasive ascidian

    NASA Astrophysics Data System (ADS)

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-03-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta.

  3. Genome-wide scans for footprints of natural selection

    PubMed Central

    Oleksyk, Taras K.; Smith, Michael W.; O'Brien, Stephen J.

    2010-01-01

    Detecting recent selected ‘genomic footprints’ applies directly to the discovery of disease genes and in the imputation of the formative events that molded modern population genetic structure. The imprints of historic selection/adaptation episodes left in human and animal genomes allow one to interpret modern and ancestral gene origins and modifications. Current approaches to reveal selected regions applied in genome-wide selection scans (GWSSs) fall into eight principal categories: (I) phylogenetic footprinting, (II) detecting increased rates of functional mutations, (III) evaluating divergence versus polymorphism, (IV) detecting extended segments of linkage disequilibrium, (V) evaluating local reduction in genetic variation, (VI) detecting changes in the shape of the frequency distribution (spectrum) of genetic variation, (VII) assessing differentiating between populations (FST), and (VIII) detecting excess or decrease in admixture contribution from one population. Here, we review and compare these approaches using available human genome-wide datasets to provide independent verification (or not) of regions found by different methods and using different populations. The lessons learned from GWSSs will be applied to identify genome signatures of historic selective pressures on genes and gene regions in other species with emerging genome sequences. This would offer considerable potential for genome annotation in functional, developmental and evolutionary contexts. PMID:20008396

  4. Natural selection and infectious disease in human populations.

    PubMed

    Karlsson, Elinor K; Kwiatkowski, Dominic P; Sabeti, Pardis C

    2014-06-01

    The ancient biological 'arms race' between microbial pathogens and humans has shaped genetic variation in modern populations, and this has important implications for the growing field of medical genomics. As humans migrated throughout the world, populations encountered distinct pathogens, and natural selection increased the prevalence of alleles that are advantageous in the new ecosystems in both host and pathogens. This ancient history now influences human infectious disease susceptibility and microbiome homeostasis, and contributes to common diseases that show geographical disparities, such as autoimmune and metabolic disorders. Using new high-throughput technologies, analytical methods and expanding public data resources, the investigation of natural selection is leading to new insights into the function and dysfunction of human biology.

  5. Natural selection and infectious disease in human populations

    PubMed Central

    Karlsson, Elinor K.; Kwiatkowski, Dominic P.; Sabeti, Pardis C.

    2015-01-01

    The ancient biological 'arms race' between microbial pathogens and humans has shaped genetic variation in modern populations, and this has important implications for the growing field of medical genomics. As humans migrated throughout the world, populations encountered distinct pathogens, and natural selection increased the prevalence of alleles that are advantageous in the new ecosystems in both host and pathogens. This ancient history now influences human infectious disease susceptibility and microbiome homeostasis, and contributes to common diseases that show geographical disparities, such as autoimmune and metabolic disorders. Using new high-throughput technologies, analytical methods and expanding public data resources, the investigation of natural selection is leading to new insights into the function and dysfunction of human biology. PMID:24776769

  6. Programed Death is Favored by Natural Selection in Spatial Systems

    NASA Astrophysics Data System (ADS)

    Werfel, Justin; Ingber, Donald E.; Bar-Yam, Yaneer

    2015-06-01

    Standard evolutionary theories of aging and mortality, implicitly based on mean-field assumptions, hold that programed mortality is untenable, as it opposes direct individual benefit. We show that in spatial models with local reproduction, programed deaths instead robustly result in long-term benefit to a lineage, by reducing local environmental resource depletion via spatiotemporal patterns causing feedback over many generations. Results are robust to model variations, implying that direct selection for shorter life span may be quite widespread in nature.

  7. Natural Selection and Genetic Diversity in the Butterfly Heliconius melpomene

    PubMed Central

    Martin, Simon H.; Möst, Markus; Palmer, William J.; Salazar, Camilo; McMillan, W. Owen; Jiggins, Francis M.; Jiggins, Chris D.

    2016-01-01

    A combination of selective and neutral evolutionary forces shape patterns of genetic diversity in nature. Among the insects, most previous analyses of the roles of drift and selection in shaping variation across the genome have focused on the genus Drosophila. A more complete understanding of these forces will come from analyzing other taxa that differ in population demography and other aspects of biology. We have analyzed diversity and signatures of selection in the neotropical Heliconius butterflies using resequenced genomes from 58 wild-caught individuals of Heliconius melpomene and another 21 resequenced genomes representing 11 related species. By comparing intraspecific diversity and interspecific divergence, we estimate that 31% of amino acid substitutions between Heliconius species are adaptive. Diversity at putatively neutral sites is negatively correlated with the local density of coding sites as well as nonsynonymous substitutions and positively correlated with recombination rate, indicating widespread linked selection. This process also manifests in significantly reduced diversity on longer chromosomes, consistent with lower recombination rates. Although hitchhiking around beneficial nonsynonymous mutations has significantly shaped genetic variation in H. melpomene, evidence for strong selective sweeps is limited overall. We did however identify two regions where distinct haplotypes have swept in different populations, leading to increased population differentiation. On the whole, our study suggests that positive selection is less pervasive in these butterflies as compared to fruit flies, a fact that curiously results in very similar levels of neutral diversity in these very different insects. PMID:27017626

  8. Substitution rate and natural selection in parvovirus B19

    PubMed Central

    Stamenković, Gorana G.; Ćirković, Valentina S.; Šiljić, Marina M.; Blagojević, Jelena V.; Knežević, Aleksandra M.; Joksić, Ivana D.; Stanojević, Maja P.

    2016-01-01

    The aim of this study was to estimate substitution rate and imprints of natural selection on parvovirus B19 genotype 1. Studied datasets included 137 near complete coding B19 genomes (positions 665 to 4851) for phylogenetic and substitution rate analysis and 146 and 214 partial genomes for selection analyses in open reading frames ORF1 and ORF2, respectively, collected 1973–2012 and including 9 newly sequenced isolates from Serbia. Phylogenetic clustering assigned majority of studied isolates to G1A. Nucleotide substitution rate for total coding DNA was 1.03 (0.6–1.27) x 10−4 substitutions/site/year, with higher values for analyzed genome partitions. In spite of the highest evolutionary rate, VP2 codons were found to be under purifying selection with rare episodic positive selection, whereas codons under diversifying selection were found in the unique part of VP1, known to contain B19 immune epitopes important in persistent infection. Analyses of overlapping gene regions identified nucleotide positions under opposite selective pressure in different ORFs, suggesting complex evolutionary mechanisms of nucleotide changes in B19 viral genomes. PMID:27775080

  9. Preventing Alzheimer's disease by means of natural selection

    PubMed Central

    Demetrius, Lloyd A.; Driver, Jane A.

    2015-01-01

    The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes. PMID:25551134

  10. Natural selection against a circadian clock gene mutation in mice.

    PubMed

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S I; Hau, Michaela

    2016-01-19

    Circadian rhythms with an endogenous period close to or equal to the natural light-dark cycle are considered evolutionarily adaptive ("circadian resonance hypothesis"). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness.

  11. Preventing Alzheimer's disease by means of natural selection.

    PubMed

    Demetrius, Lloyd A; Driver, Jane A

    2015-01-06

    The amyloid cascade model for the origin of sporadic forms of Alzheimer's disease (AD) posits that the imbalance in the production and clearance of beta-amyloid is a necessary condition for the disease. A competing theory called the entropic selection hypothesis asserts that the primary cause of sporadic AD is age-induced mitochondrial dysregulation and the following cascade of events: (i) metabolic reprogramming—the upregulation of oxidative phosphorylation in compensation for insufficient energy production in neurons, (ii) natural selection—competition between intact and reprogrammed neurons for energy substrates and (iii) propagation—the spread of the disease due to the selective advantage of neurons with upregulated metabolism. Experimental studies to evaluate the predictions of the amyloid cascade model are being continually retuned to accommodate conflicts of the predictions with empirical data. Clinical trials of treatments for AD based on anti-amyloid therapy have been unsuccessful. We contend that these anomalies and failures stem from a fundamental deficit of the amyloid hypothesis: the model derives from a nuclear-genomic perspective of sporadic AD and discounts the bioenergetic processes that characterize the progression of most age-related disorders. In this article, we review the anomalies of the amyloid model and the theoretical and empirical support for the entropic selection theory. We also discuss the new therapeutic strategies based on natural selection which the model proposes.

  12. Natural selection against a circadian clock gene mutation in mice

    PubMed Central

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S. I.; Hau, Michaela

    2016-01-01

    Circadian rhythms with an endogenous period close to or equal to the natural light–dark cycle are considered evolutionarily adaptive (“circadian resonance hypothesis”). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness. PMID:26715747

  13. Using David Lack's Observations of Finch Beak Size to Teach Natural Selection & the Nature of Science

    ERIC Educational Resources Information Center

    Bierema, Andrea M.-K.; Rudge, David W.

    2014-01-01

    One of the key aspects of natural selection is competition, yet the concept of competition is not necessarily emphasized in explanations of natural selection. Because of this, we developed an activity for our class that focuses on competition and provides an example of the effects of competition on natural selection. This hands-on activity models…

  14. Using David Lack's Observations of Finch Beak Size to Teach Natural Selection & the Nature of Science

    ERIC Educational Resources Information Center

    Bierema, Andrea M.-K.; Rudge, David W.

    2014-01-01

    One of the key aspects of natural selection is competition, yet the concept of competition is not necessarily emphasized in explanations of natural selection. Because of this, we developed an activity for our class that focuses on competition and provides an example of the effects of competition on natural selection. This hands-on activity models…

  15. WordlePlus: Expanding Wordle's Use through Natural Interaction and Animation.

    PubMed

    Jo, Jaemin; Lee, Bongshin; Seo, Jinwook

    2015-01-01

    Wordle has been commonly used to summarize texts, with each word size-coded by its frequency of occurrences--the more often a word occurs in texts, the bigger it is. The interactive authoring tool WordlePlus leverages natural interaction and animation to give users more control over wordle development. WordlePlus supports direct manipulation of words with pen and touch interaction. It introduces two-word multitouch manipulation, such as concatenating and grouping two words, and provides pen interaction for adding and deleting words. In addition, WordlePlus employs animation to help users create more dynamic and engaging wordles.

  16. Natural selection in the field and the classroom

    NASA Astrophysics Data System (ADS)

    Andrews, Tessa Marie

    This dissertation examined natural selection in westslope cutthroat trout (Oncorhynchus clarkii lewisi) and undergraduate learning in the subject area natural selection. Translocation---moving individuals to a new habitat to establish, re-establish or supplement a population---is a crucial management strategy for cutthroat trout. One of the major questions managers face in a translocation is which population(s) should contribute individuals? Unfortunately, we often know little about the differences among potential contributing population. The goal of the first half of this dissertation was to look for differences in performance among individuals from five populations of westslope cutthroat trout. I assessed survival, growth, and condition (Chapter 2) and dispersal (Chapter 3) following the translocation of embryos from these five populations to six introduction sites in Cherry Creek. No differences existed among these populations in relative survival, growth, or condition at age 1 or 2. In contrast, statistically significant differences existed in dispersal distance among these populations. These differences were consistent across some, but not all, introduction locations. As our knowledge of evolutionary biology has continued to grow, so too has our knowledge of how students learn evolution. Students taught using active learning strategies can learn substantially more about complex scientific concepts than students taught using primarily lectures. The goal of the second half of this dissertation was to further examine how students learn natural selection and how instructors facilitate that learning. I conducted a national survey of the relationship between an instructor's use of active learning strategies and how much students learned about natural selection (Chapter 4). I used a random sample of instructors from the largest and most prestigious universities in the country so that my results could be inferred to this large population of instructors. The degree to

  17. A rational design for the nanoencapsulation of poisonous animal venoms in liposomes prepared with natural phospholipids.

    PubMed

    da Costa, Maria Helena Bueno; Sant'Anna, Osvaldo A; Quintilio, Wagner; Schwendener, Reto Albert; de Araujo, Pedro Soares

    2012-11-01

    Liposomes have been used since the 1970's to encapsulate drugs envisaging enhancement in efficacy and therapeutic index, avoidance of side effects and increase in the encapsulated agent stability. The major problem when encapsulating snake venoms is the liposomal membrane instability caused by venom phospholipases. Here the results obtained encapsulating Crotalus durissimus terrificus and a pool of Bothropic venoms within liposomes (LC and LB, respectively) used to produce anti-venom sera are presented. The strategy was to modify the immunization protocol to enhance antibody production and to minimize toxic effects by encapsulating inactivated venoms within stabilized liposomes. Chemically modified venoms were solubilized in a buffer containing an inhibitor and a chelating agent. The structures of the venoms were analyzed by UV, CD spectroscopy and ELISA. In spite of the differences in the helical content between natural and modified venoms, they were recognized by horse anti-sera. To maintain long-term stability, mannitol was used as a cryoprotectant. The encapsulation efficiencies were 59 % (LB) and 99 % (LC), as followed by filtration on Sephacryl S1000. Light scattering measurements led us to conclude that both, LB (119 ±47 nm) and LC (147±56 nm) were stable for 22 days at 4 °C, even after lyophilization. Genetically selected mice and mixed breed horses were immunized with these formulations. The animals did not show clinical symptoms of venom toxicity. Both, LB and LC enhanced by at least 30 % the antibody titers 25 days after injection and total IgG titers remained high 91 days after immunization. The liposomal formulation clearly exhibited adjuvant properties.

  18. The role of natural selection in the origin of life.

    PubMed

    Fry, Iris

    2011-02-01

    It is commonly accepted among origin-of-life scientists that the emergence of life was an evolutionary process involving at one stage or other the working of natural selection. Researchers disagree, however, on the nature of the chemical infrastructure that could have formed prebiotically, enabling the evolutionary process. The division of the origin-of-life research community into 'geneticists' and 'metabolists' usually revolves around the issue whether the first to arise prebiotically was a genetic polymer or a primitive metabolic system. In this paper I offer an alternative classification based on the attitude to the onset of natural selection. From this perspective I add to the conventional division between gene-first and metabolism-first groups a position I call "preparatory metabolism". By this line of thought, an RNA or an RNA-like polymer could not have emerged prebiotically. Nevertheless, the onset of natural selection had to wait until such a polymer had arised. This paper examines the RNA-first, RNA-later, metabolism-first and preparatory-metabolism scenarios, assessing the weaknesses and strengths of each. I conclude that despite the recent theoretical advances in all these lines of research, and despite experimental breakthroughs, especially in overcoming several RNA-first hurdles, none of the examined paradigms has yet attained decisive experimental support. Demonstrating the evolvability of a potentially prebiotic infrastructure, whether genetic or metabolic, is a most serious challenge. So is the experimental demonstration of the emergence of such an infrastructure under prebiotic conditions. The current agenda before origin-of-life researchers of all stripes and colors is the search for the experimental means to tackle all these difficulties.

  19. How selective sweeps in domestic animals provide new insight into biological mechanisms.

    PubMed

    Andersson, L

    2012-01-01

    Genetic studies of domestic animals are of general interest because there is more phenotypic diversity to explore in these species than in any experimental organism. Some mutations with favourable phenotypic effects have been highly enriched and gone through selective sweeps during the process of domestication and selective breeding. Three such selective sweeps are described in this review. All three mutations are intronic and constitute cis-acting regulatory mutations. Two of the mutations constitute structural changes (one duplication and one copy number expansion). These examples illustrate a general trend that noncoding mutations and structural changes have both contributed significantly to the evolution of phenotypic diversity in domestic animals. How the molecular characterization of trait loci in domestic animals can provide new basic knowledge of relevance for human medicine is discussed.

  20. Evidence from pyrosequencing indicates that natural variation in animal personality is associated with DRD4 DNA methylation.

    PubMed

    Verhulst, Eveline C; Mateman, A Christa; Zwier, Mathijs V; Caro, Samuel P; Verhoeven, Koen J F; van Oers, Kees

    2016-04-01

    Personality traits are heritable and respond to natural selection, but are at the same time influenced by the ontogenetic environment. Epigenetic effects, such as DNA methylation, have been proposed as a key mechanism to control personality variation. However, to date little is known about the contribution of epigenetic effects to natural variation in behaviour. Here, we show that great tit (Parus major) lines artificially selected for divergent exploratory behaviour for four generations differ in their DNA methylation levels at the dopamine receptor D4 (DRD4) gene. This D4 receptor is statistically associated with personality traits in both humans and nonhuman animals, including the great tit. Previous work in this songbird failed to detect functional genetic polymorphisms within DRD4 that could account for the gene-trait association. However, our observation supports the idea that DRD4 is functionally involved in exploratory behaviour but that its effects are mediated by DNA methylation. While the exact mechanism underlying the transgenerational consistency of DRD4 methylation remains to be elucidated, this study shows that epigenetic mechanisms are involved in shaping natural variation in personality traits. We outline how this first finding provides a basis for investigating the epigenetic contribution to personality traits in natural systems and its subsequent role for understanding the ecology and evolution of behavioural consistency. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  1. Natural selection and divergence in mate preference during speciation.

    PubMed

    Nosil, Patrik; Crespi, Bernard J; Gries, Regine; Gries, Gerhard

    2007-03-01

    Sexual isolation can evolve due to natural selection against hybrids (reinforcement). However, many different forms of hybrid dysfunction, and selective processes that do not involve hybrids, can contribute to the evolution of sexual isolation. Here we review how different selective processes affect the evolution of sexual isolation, describe approaches for distinguishing among them, and assess how they contribute to variation in sexual isolation among populations of Timema cristinae stick-insects. Pairs of allopatric populations of T. cristinae living on different host-plant species exhibit greater sexual isolation than those on the same host, indicating that some sexual isolation has evolved due to host adaptation. Sexual isolation is strongest in regions where populations on different hosts are in geographic contact, a pattern of reproductive character displacement that is indicative of reinforcement. Ecological costs to hybridization do occur but traits under ecological selection (predation) do not co-vary strongly with the probability of between-population mating such that selection on ecological traits is not predicted to produce a strong correlated evolutionary response in mate preference. Moreover, F1 hybrid egg inviability is lacking and the factors contributing to reproductive character displacement require further study. Finally, we show that sexual isolation involves, at least in part, olfactory communication. Our results illustrate how understanding of the evolution of sexual isolation can be enhanced by isolating the roles of diverse ecological and evolutionary processes.

  2. Signatures of selection in natural populations adapted to chronic pollution.

    PubMed

    Williams, Larissa M; Oleksiak, Marjorie F

    2008-10-10

    Populations of the teleost fish Fundulus heteroclitus appear to flourish in heavily polluted and geographically separated Superfund sites. Populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) have independently evolved adaptive resistance to chemical pollutants. In these polluted populations, natural selection likely has altered allele frequencies of loci that affect fitness or that are linked to these loci. The aim of this study was to identify loci that exhibit non-neutral behavior in the F. heteroclitus genome in polluted populations versus clean reference populations. To detect signatures of natural selection and thus identify genetic bases for adaptation to anthropogenic stressors, we examined allele frequencies for many hundreds of amplified fragment length polymorphism markers among populations of F. heteroclitus. Specifically, we contrasted populations from three Superfund sites (New Bedford Harbor, MA, Newark Bay, NJ, and Elizabeth River, VA) to clean reference populations flanking the polluted sites. When empirical FST values were compared to a simulated distribution of FST values, 24 distinct outlier loci were identified among pairwise comparisons of pollutant impacted F. heteroclitus populations and both surrounding reference populations. Upon removal of all outlier loci, there was a strong correlation (R2=0.79, p<0.0001) between genetic and geographical distance. This apparently neutral evolutionary pattern was not evident when outlier loci were included (R2=0.092, p=0.0721). Two outlier loci were shared between New Bedford Harbor and Elizabeth River populations, and two different loci were shared between Newark Bay and Elizabeth River populations. In total, 1% to 6% of loci are implicated as being under selection or linked to areas of the genome under selection in three F. heteroclitus populations that reside in polluted estuaries. Shared loci among polluted sites indicate that selection may be

  3. [Vancomycin-resistant enterococci - the nature of resistance and risk of transmission from animals to humans].

    PubMed

    Hermanovská, Lýdia; Bardoň, Jan; Čermák, Pavel

    2016-06-01

    Enterococci are part of the normal intestinal flora of humans and animals. Under certain circumstances, they are capable of extraintestinal conversion to opportunistic pathogens. They cause endogenous as well as exogenous community and nosocomial infections. The gastrointestinal tract of mammals provides them with favorable conditions for acquisition and spread of resistance genes, for example to vancomycin (van), from other symbiotic bacteria. Thus, vancomycin-resistant enterococci (VRE) become potential reservoirs and vectors of the van genes. Their occurrence in the population of the Czech Republic was first reported by Kolář et al. in 1997. Some variants of the vanA gene cluster carried on Tn1546 which encode resistance to vancomycin are identical in humans and in animals. It means that animals, especially cattle, poultry and pigs, could be an important reservoir of VRE for humans. Kolář and Bardoň detected VRE in animals in the Czech Republic for the first time in 2000. In Europe, the glycopeptide antibiotic avoparcin, used as a growth stimulator, is responsible for selection of VRE strains in animals. Strains of Enterococcus faecium from animals may offer genes of antimicrobial resistance to other enterococci or they can be directly dangerous to human. This is demonstrated by finding isolates of E. faecalis from human patients and from pigs having very similar profiles of resistance and virulence genes. The goal of the paper was to point out the similarity between isolates of human and animal strains of enterococci resistant to vancomycin, and the possibility of their bilateral transfer between humans and animals.

  4. Evolution of behavior by density-dependent natural selection

    SciTech Connect

    Pingzhong Guo; Mueller, L.D.; Ayala, F.J. )

    1991-12-01

    Theories of density-dependent natural selection predict that evolution should favor those genotypes with the highest per capita rates of population growth under the current density conditions. These theories are silent about the mechanisms that may give rise to these increases in density-dependent growth rates. The authors have observed the evolution of six populations of Drosophila melanogaster recently placed in crowded environments after nearly 200 generations at low-population density in the laboratory. After 25 generations in these crowded cultures all six populations showed the predicted increase in population growth rates at high-population density with the concomitant decrease in their growth rates at low densities. These changes in rates of population growth are accompanied by changes in the feeding and pupation behavior of the larvae: those populations that have evolve at high-population densities have higher feeding rates and are less likely to pupate on or near the food surface than populations maintained at low densities. A detailed understanding of the mechanisms by which populations evolve under density-dependent natural selection will provide a framework for understanding that nature of trade-offs in life history evolution.

  5. The Emergence of Physiology and Form: Natural Selection Revisited

    PubMed Central

    Torday, John S.

    2016-01-01

    Natural Selection describes how species have evolved differentially, but it is descriptive, non-mechanistic. What mechanisms does Nature use to accomplish this feat? One known way in which ancient natural forces affect development, phylogeny and physiology is through gravitational effects that have evolved as mechanotransduction, seen in the lung, kidney and bone, linking as molecular homologies to skin and brain. Tracing the ontogenetic and phylogenetic changes that have facilitated mechanotransduction identifies specific homologous cell-types and functional molecular markers for lung homeostasis that reveal how and why complex physiologic traits have evolved from the unicellular to the multicellular state. Such data are reinforced by their reverse-evolutionary patterns in chronic degenerative diseases. The physiologic responses of model organisms like Dictyostelium and yeast to gravity provide deep comparative molecular phenotypic homologies, revealing mammalian Target of Rapamycin (mTOR) as the final common pathway for vertical integration of vertebrate physiologic evolution; mTOR integrates calcium/lipid epistatic balance as both the proximate and ultimate positive selection pressure for vertebrate physiologic evolution. The commonality of all vertebrate structure-function relationships can be reduced to calcium/lipid homeostatic regulation as the fractal unit of vertebrate physiology, demonstrating the primacy of the unicellular state as the fundament of physiologic evolution. PMID:27534726

  6. Natural selection by pulsed predation: survival of the thickest.

    PubMed

    Bijleveld, Aller I; Twietmeyer, Sönke; Piechocki, Julia; van Gils, Jan A; Piersma, Theunis

    2015-07-01

    Selective predation can lead to natural selection in prey populations and may alleviate competition among surviving individuals. The processes of selection and competition can have substantial effects on prey population dynamics, but are rarely studied simultaneously. Moreover, field studies of predator-induced short-term selection pressures on prey populations are scarce. Here we report measurements of density dependence in body composition in a bivalve prey (edible cockle, Cerastoderma edule) during bouts of intense predation by an avian predator (Red Knot, Calidris canutus). We measured densities, patchiness, morphology, and body composition (shell and flesh mass) of cockles in a quasi-experimental setting, i.e., before and after predation in three similar plots of 1 ha each, two of which experienced predation, and one of which remained unvisited in the course of the short study period and served as a reference. An individual's shell and flesh mass declined with cockle density (negative density dependence). Before predation, cockles were patchily distributed. After predation, during which densities were reduced by 78% (from 232 to 50 cockles/m2), the patchiness was substantially reduced, i.e., the spatial distribution was homogenized. Red Knots selected juvenile cockles with an average length of 6.9 ± 1.0 mm (mean ± SD). Cockles surviving predation had heavier shells than before predation (an increase of 21.5 percentage points), but similar flesh masses. By contrast, in the reference plot shell mass did not differ statistically between initial and final sampling occasions, while flesh mass was larger (an increase of 13.2 percentage points). In this field study, we show that Red Knots imposed a strong selection pressure on cockles to grow fast with thick shells and little flesh mass, with selection gradients among the highest reported in the literature.

  7. Articular Osteochondrosis: A Comparison of Naturally-Occurring Human and Animal Disease

    PubMed Central

    McCoy, Annette M; Toth, Ferenc; Dolvik, Nils I; Ekman, Stina; Ellermann, Jutta; Olstad, Kristin; Ytrehus, Bjornar; Carlson, Cathy S

    2013-01-01

    Background Osteochondrosis (OC) is a common developmental orthopedic disease affecting both humans and animals. Despite increasing recognition of this disease among children and adolescents, its pathogenesis is incompletely understood because clinical signs are often not apparent until lesions have progressed to end-stage, and examination of cadaveric early lesions is not feasible. In contrast, both naturally-occurring and surgically-induced animal models of disease have been extensively studied, most notably in horses and swine, species in which OC is recognized to have profound health and economic implications. The potential for a translational model of human OC has not been recognized in the existing human literature. Objective The purpose of this review is to highlight the similarities in signalment, predilection sites and clinical presentation of naturally-occurring OC in humans and animals and to propose a common pathogenesis for this condition across species. Study Design Review Methods The published human and veterinary literature for the various manifestations of OC was reviewed. Peer-reviewed original scientific articles and species-specific review articles accessible in PubMed (US National Library of Medicine) were eligible for inclusion. Results A broad range of similarities exists between OC affecting humans and animals, including predilection sites, clinical presentation, radiographic/MRI changes, and histological appearance of the end stage lesion, suggesting a shared pathogenesis across species. Conclusion This proposed shared pathogenesis for OC between species implies that naturally-occurring and surgically-induced models of OC in animals may be useful in determining risk factors and for testing new diagnostic and therapeutic interventions that can be used in humans. PMID:23954774

  8. Population thinking and natural selection in dual-inheritance theory.

    PubMed

    Houkes, Wybo

    2012-05-01

    A deflationary perspective on theories of cultural evolution, in particular dual-inheritance theory, has recently been proposed by Lewens. On this 'pop-culture' analysis, dual-inheritance theorists apply population thinking to cultural phenomena, without claiming that cultural items evolve by natural selection. This paper argues against this pop-culture analysis of dual-inheritance theory. First, it focuses on recent dual-inheritance models of specific patterns of cultural change. These models exemplify population thinking without a commitment to natural selection of cultural items. There are grounds, however, for doubting the added explanatory value of the models in their disciplinary context-and thus grounds for engaging in other potentially explanatory projects based on dual-inheritance theory. One such project is suggested by advocates of the theory. Some of the motivational narratives that they offer can be interpreted as setting up an adaptationist project with regard to cumulative change in cultural items. We develop this interpretation here. On it, dual-inheritance theory features two interrelated selection processes, one on the level of genetically inherited learning mechanisms, another on the level of the cultural items transmitted through these mechanisms. This interpretation identifies a need for further modelling efforts, but also offers scope for enhancing the explanatory power of dual-inheritance theory.

  9. Lifetime selection on heritable life-history traits in a natural population of red squirrels.

    PubMed

    Réale, D; Berteaux, D; McAdam, A G; Boutin, S

    2003-10-01

    Despite their importance in evolutionary biology, heritability and the strength of natural selection have rarely been estimated in wild populations of iteroparous species or have usually been limited to one particular event during an organism's lifetime. Using an animal-model restricted maximum likelihood and phenotypic selection models, we estimated quantitative genetic parameters and the strength of lifetime selection on parturition date and litter size at birth in a natural population of North American red squirrels, Tamiasciurus hudsonicus. Litter size at birth and parturition date had low heritabilities (h2 = 0.15 and 0.16, respectively). We considered potential effects of temporal environmental covariances between phenotypes and fitness and of spatial environmental heterogeneity in estimates of selection. Selection favored early breeders and females that produced litter sizes close to the population average. Stabilizing selection on litter size at birth may occur because of a trade-off between number of offspring produced per litter and offspring survival or a trade-off between a female's fecundity and her future reproductive success and survival.

  10. The 'Disadapted' Animal: Niko Tinbergen on Human Nature and the Human Predicament.

    PubMed

    Vicedo, Marga

    2017-07-18

    This paper explores ethologist Niko Tinbergen's path from animal to human studies in the 1960s and 1970s and his views about human nature. It argues, first, that the confluence of several factors explains why Tinbergen decided to cross the animal/human divide in the mid 1960s: his concern about what he called "the human predicament," his relations with British child psychiatrist John Bowlby, the success of ethological explanations of human behavior, and his professional and personal situation. It also argues that Tinbergen transferred his general adaptationist view of animal behavior to the realm of human biology; here, his concern about disadaptation led him to a view of human behavior that was strongly determined by the species' evolutionary past, a position that I call evolutionary determinism. These ideas can be seen in the work he carried out with his wife, Elisabeth Tinbergen, on autism. The paper concludes that Tinbergen's vision of human nature constitutes another version of what anthropologist Clifford Geertz called in 1966 the "stratigraphic" conception of the human: a view of human nature as a composite of levels in which a universal ancestral biological core is superimposed by psychological and cultural layers that represent accidental variation at best and pathological deviation at worst.

  11. Overlapping neural response to the pain or harm of people, animals, and nature.

    PubMed

    Mathur, Vani A; Cheon, Bobby K; Harada, Tokiko; Scimeca, Jason M; Chiao, Joan Y

    2016-01-29

    Interpersonal pain perception is a fundamental and evolutionarily beneficial social process. While critical for navigating the social world, whether or not people rely on similar processes to perceive and respond to the harm of the non-human biological world remains largely unknown. Here we investigate whether neural reactivity toward the suffering of other people is distinct from or overlapping with the neural response to pain and harm inflicted upon non-human entities, specifically animals and nature. We used fMRI to measure neural activity while participants (n=15) perceived and reported how badly they felt for the pain or harm of humans, animals, and nature, relative to neutral situations. Neural regions associated with perceiving the pain of other people (e.g. dorsal anterior cingulate cortex, bilateral anterior insula) were similarly recruited when perceiving and responding to painful scenes across people, animals, and nature. These results suggest that similar brain responses are relied upon when perceiving the harm of social and non-social biological entities, broadly construed, and that activity within the dorsal anterior cingulate cortex and bilateral anterior insula in response to pain-relevant stimuli is not uniquely specific to humans. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Exploring natural selection to guide breeding for agriculture.

    PubMed

    Henry, Robert James; Nevo, Eviatar

    2014-08-01

    Climate change threatens reduced crop production and poses major challenges to food security. The breeding of climate-resilient crop varieties is increasingly urgent. Wild plant populations evolve to cope with changes in their environment due to the forces of natural selection. This adaptation may be followed over time in populations at the same site or explored by examining differences between populations growing in different environments or across an environmental gradient. Survival in the wild has important differences to the objective of agriculture to maximize crop yields. However, understanding the nature of adaptation in wild populations at the whole genome level may suggest strategies for crop breeding to deliver agricultural production with more resilience to climate variability. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  13. The natural selection of fidelity in social learning

    PubMed Central

    Sperber, Dan

    2010-01-01

    Social learning mechanisms are usually assumed to explain both the spread and the persistence of cultural behavior. In a recent article, we showed that the fidelity of social learning commonly found in transmission chain experiments is not high enough to explain cultural stability. Here we want to both enrich and qualify this conclusion by looking at the case of song transmission in song birds, which can be faithful to the point of being true replication. We argue that this high fidelity results from natural selection pressure on cognitive mechanisms. This observation strengthens our main argument. Social learning mechanisms are unlikely to be faithful enough to explain cultural stability because they are generally selected not for high fidelity but for generalization and adjustment to the individual’s needs, capacities and situation. PMID:20798823

  14. [Natural fruit colour selection by frugivorous birds in Xishuangbanna].

    PubMed

    Duan, Qiong; Quan, Rui-Chang

    2012-10-01

    Black and red are the most common colors of fruit, but the reason behind this has been subject to debate. Food preferences of avian frugivores for certain colors of food have been proposed as a selection mechanism that explains these traits, but there is little evidence supporting this hypothesis. Here, we conducted a lab experiment using four colors of natural fruit to evaluate color preferences of five avian species, and we also conducted this experiment in open area and understory habitats. Our results showed that red and black fruits were selected most often in lab experiment; in field experiment, red and black fruits were also the most preferred food, but the total amount of consumed fruits differed significantly between open areas and understory habitats. Our study suggested that differences in color preferences among frugivores may potentially reflect the diversity of fruit color and frequency in Xishuangbanna.

  15. Kaon condensation, black holes, and cosmological natural selection.

    PubMed

    Brown, G E; Lee, Chang-Hwan; Rho, Mannque

    2008-08-29

    It is argued that a well-measured double neutron-star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M > or approximately 2M(middle dot in circle) would put in serious doubt or simply falsify the following chain of predictions: (1) a nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n-3n0, (3) the Brown-Bethe maximum neutron-star mass Mmax approximately 1.5M(middle dot in circle), and (4) Smolin's "cosmological natural selection" hypothesis.

  16. Natural selection drives chemical resistance of Datura stramonium.

    PubMed

    Miranda-Pérez, Adán; Castillo, Guillermo; Hernández-Cumplido, Johnattan; Valverde, Pedro L; Borbolla, María; Cruz, Laura L; Tapia-López, Rosalinda; Fornoni, Juan; Flores-Ortiz, César M; Núñez-Farfán, Juan

    2016-01-01

    Plant resistance to herbivores involves physical and chemical plant traits that prevent or diminish damage by herbivores, and hence may promote coevolutionary arm-races between interacting species. Although Datura stramonium's concentration of tropane alkaloids is under selection by leaf beetles, it is not known whether chemical defense reduces seed predation by the specialist weevil, Trichobaris soror, and if it is evolving by natural selection. We measured infestation by T. soror as well as the concentration of the plants' two main tropane alkaloids in 278 D. stramonium plants belonging to 31 populations in central Mexico. We assessed whether the seed predator exerted preferences on the levels of both alkaloids and whether they affect plant fitness. Results show great variation across populations in the concentration of scopolamine and atropine in both leaves and seeds of plants of D. stramonium, as well as in the intensity of infestation and the proportion of infested fruits by T. soror. The concentration of scopolamine in seeds and leaves are negatively associated across populations. We found that scopolamine concentration increases plant fitness. Our major finding was the detection of a positive relationship between the population average concentrations of scopolamine with the selection differentials of scopolamine. Such spatial variation in the direction and intensity of selection on scopolamine may represent a coevolutionary selective mosaic. Our results support the view that variation in the concentration of scopolamine among-populations of D. stramonium in central Mexico is being driven, in part, by selection exerted by T. soror, pointing an adaptive role of tropane alkaloids in this plant species.

  17. Natural selection drives chemical resistance of Datura stramonium

    PubMed Central

    Miranda-Pérez, Adán; Castillo, Guillermo; Hernández-Cumplido, Johnattan; Valverde, Pedro L.; Borbolla, María; Cruz, Laura L.; Tapia-López, Rosalinda; Fornoni, Juan; Flores-Ortiz, César M.

    2016-01-01

    Plant resistance to herbivores involves physical and chemical plant traits that prevent or diminish damage by herbivores, and hence may promote coevolutionary arm-races between interacting species. Although Datura stramonium’s concentration of tropane alkaloids is under selection by leaf beetles, it is not known whether chemical defense reduces seed predation by the specialist weevil, Trichobaris soror, and if it is evolving by natural selection. We measured infestation by T. soror as well as the concentration of the plants’ two main tropane alkaloids in 278 D. stramonium plants belonging to 31 populations in central Mexico. We assessed whether the seed predator exerted preferences on the levels of both alkaloids and whether they affect plant fitness. Results show great variation across populations in the concentration of scopolamine and atropine in both leaves and seeds of plants of D. stramonium, as well as in the intensity of infestation and the proportion of infested fruits by T. soror. The concentration of scopolamine in seeds and leaves are negatively associated across populations. We found that scopolamine concentration increases plant fitness. Our major finding was the detection of a positive relationship between the population average concentrations of scopolamine with the selection differentials of scopolamine. Such spatial variation in the direction and intensity of selection on scopolamine may represent a coevolutionary selective mosaic. Our results support the view that variation in the concentration of scopolamine among-populations of D. stramonium in central Mexico is being driven, in part, by selection exerted by T. soror, pointing an adaptive role of tropane alkaloids in this plant species. PMID:27114866

  18. Selection maintains MHC diversity through a natural population bottleneck.

    PubMed

    Oliver, Matthew K; Piertney, Stuart B

    2012-07-01

    A perceived consequence of a population bottleneck is the erosion of genetic diversity and concomitant reduction in individual fitness and evolutionary potential. Although reduced genetic variation associated with demographic perturbation has been amply demonstrated for neutral molecular markers, the effective management of genetic resources in natural populations is hindered by a lack of understanding of how adaptive genetic variation will respond to population fluctuations, given these are affected by selection as well as drift. Here, we demonstrate that selection counters drift to maintain polymorphism at a major histocompatibility complex (MHC) locus through a population bottleneck in an inbred island population of water voles. Before and after the bottleneck, MHC allele frequencies were close to balancing selection equilibrium but became skewed by drift when the population size was critically low. MHC heterozygosity generally conformed to Hardy-Weinberg expectations except in one generation during the population recovery where there was a significant excess of heterozygous genotypes, which simulations ascribed to strong differential MHC-dependent survival. Low allelic diversity and highly skewed frequency distributions at microsatellite loci indicated potent genetic drift due to a strong founder affect and/or previous population bottlenecks. This study is a real-time examination of the predictions of fundamental evolutionary theory in low genetic diversity situations. The findings highlight that conservation efforts to maintain the genetic health and evolutionary potential of natural populations should consider the genetic basis for fitness-related traits, and how such adaptive genetic diversity will vary in response to both the demographic fluctuations and the effects of selection.

  19. The Impact of Designing and Evaluating Molecular Animations on How Well Middle School Students Understand the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Chang, Hsin-Yi; Quintana, Chris; Krajcik, Joseph S.

    2010-01-01

    In this study, we investigated whether the understanding of the particulate nature of matter by students was improved by allowing them to design and evaluate molecular animations of chemical phenomena. We developed Chemation, a learner-centered animation tool, to allow seventh-grade students to construct flipbook-like simple animations to show…

  20. The Impact of Designing and Evaluating Molecular Animations on How Well Middle School Students Understand the Particulate Nature of Matter

    ERIC Educational Resources Information Center

    Chang, Hsin-Yi; Quintana, Chris; Krajcik, Joseph S.

    2010-01-01

    In this study, we investigated whether the understanding of the particulate nature of matter by students was improved by allowing them to design and evaluate molecular animations of chemical phenomena. We developed Chemation, a learner-centered animation tool, to allow seventh-grade students to construct flipbook-like simple animations to show…

  1. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons.

    PubMed

    Baudot, Pierre; Levy, Manuel; Marre, Olivier; Monier, Cyril; Pananceau, Marc; Frégnac, Yves

    2013-01-01

    Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) "spike-less" periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non-linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: (1) broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; (2) tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; (3) signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual dense

  2. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons

    PubMed Central

    Baudot, Pierre; Levy, Manuel; Marre, Olivier; Monier, Cyril; Pananceau, Marc; Frégnac, Yves

    2013-01-01

    Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10–20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) “spike-less” periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non-linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: (1) broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; (2) tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; (3) signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual

  3. Pairing Animal Cartoon Characters with Produce Stimulates Selection among Child Zoo Visitors

    ERIC Educational Resources Information Center

    Karpyn, Allison; Allen, Michael; Marks, Samantha; Filion, Nicole; Humphrey, Debora; Ye, Ai; May, Henry; Gardner, Meryl P.

    2017-01-01

    In order to address the pervasive trend of underconsumption of fruits and vegetables among children, we examined the hypothesis that children would be more likely to select fruits (apple slices, bananas, and oranges) and vegetables (baby carrots) when paired with animal cartoon image than when available without the character image. Tested in a…

  4. Selection of the intrinsic polarization properties of animal optical materials creates enhanced structural reflectivity and camouflage

    PubMed Central

    Feller, Kathryn D.; Jordan, Thomas M.

    2017-01-01

    Many animals use structural coloration to create bright and conspicuous visual signals. Selection of the size and shape of the optical structures animals use defines both the colour and intensity of the light reflected. The material used to create these reflectors is also important; however, animals are restricted to a limited number of materials: commonly chitin, guanine and the protein, reflectin. In this work we highlight that a particular set of material properties can also be under selection in order to increase the optical functionality of structural reflectors. Specifically, polarization properties, such as birefringence (the difference between the refractive indices of a material) and chirality (which relates to molecular asymmetry) are both under selection to create enhanced structural reflectivity. We demonstrate that the structural coloration of the gold beetle Chrysina resplendens and silvery reflective sides of the Atlantic herring, Clupea harengus are two examples of this phenomenon. Importantly, these polarization properties are not selected to control the polarization of the reflected light as a source of visual information per se. Instead, by creating higher levels of reflectivity than are otherwise possible, such internal polarization properties improve intensity-matching camouflage. This article is part of the themed issue ‘Animal coloration: production, perception, function and application’. PMID:28533453

  5. Animal selection for whole genome sequencing by quantifying the unique contribution of homozygous haplotypes sequenced

    USDA-ARS?s Scientific Manuscript database

    Major whole genome sequencing projects promise to identify rare and causal variants within livestock species; however, the efficient selection of animals for sequencing remains a major problem within these surveys. The goal of this project was to develop a library of high accuracy genetic variants f...

  6. Human-induced evolution caused by unnatural selection through harvest of wild animals.

    PubMed

    Allendorf, Fred W; Hard, Jeffrey J

    2009-06-16

    Human harvest of phenotypically desirable animals from wild populations imposes selection that can reduce the frequencies of those desirable phenotypes. Hunting and fishing contrast with agricultural and aquacultural practices in which the most desirable animals are typically bred with the specific goal of increasing the frequency of desirable phenotypes. We consider the potential effects of harvest on the genetics and sustainability of wild populations. We also consider how harvesting could affect the mating system and thereby modify sexual selection in a way that might affect recruitment. Determining whether phenotypic changes in harvested populations are due to evolution, rather than phenotypic plasticity or environmental variation, has been problematic. Nevertheless, it is likely that some undesirable changes observed over time in exploited populations (e.g., reduced body size, earlier sexual maturity, reduced antler size, etc.) are due to selection against desirable phenotypes-a process we call "unnatural" selection. Evolution brought about by human harvest might greatly increase the time required for over-harvested populations to recover once harvest is curtailed because harvesting often creates strong selection differentials, whereas curtailing harvest will often result in less intense selection in the opposing direction. We strongly encourage those responsible for managing harvested wild populations to take into account possible selective effects of harvest management and to implement monitoring programs to detect exploitation-induced selection before it seriously impacts viability.

  7. Human-induced evolution caused by unnatural selection through harvest of wild animals

    PubMed Central

    Allendorf, Fred W.; Hard, Jeffrey J.

    2009-01-01

    Human harvest of phenotypically desirable animals from wild populations imposes selection that can reduce the frequencies of those desirable phenotypes. Hunting and fishing contrast with agricultural and aquacultural practices in which the most desirable animals are typically bred with the specific goal of increasing the frequency of desirable phenotypes. We consider the potential effects of harvest on the genetics and sustainability of wild populations. We also consider how harvesting could affect the mating system and thereby modify sexual selection in a way that might affect recruitment. Determining whether phenotypic changes in harvested populations are due to evolution, rather than phenotypic plasticity or environmental variation, has been problematic. Nevertheless, it is likely that some undesirable changes observed over time in exploited populations (e.g., reduced body size, earlier sexual maturity, reduced antler size, etc.) are due to selection against desirable phenotypes—a process we call “unnatural” selection. Evolution brought about by human harvest might greatly increase the time required for over-harvested populations to recover once harvest is curtailed because harvesting often creates strong selection differentials, whereas curtailing harvest will often result in less intense selection in the opposing direction. We strongly encourage those responsible for managing harvested wild populations to take into account possible selective effects of harvest management and to implement monitoring programs to detect exploitation-induced selection before it seriously impacts viability. PMID:19528656

  8. Evidence for evolution in response to natural selection in a contemporary human population.

    PubMed

    Milot, Emmanuel; Mayer, Francine M; Nussey, Daniel H; Boisvert, Mireille; Pelletier, Fanie; Réale, Denis

    2011-10-11

    It is often claimed that modern humans have stopped evolving because cultural and technological advancements have annihilated natural selection. In contrast, recent studies show that selection can be strong in contemporary populations. However, detecting a response to selection is particularly challenging; previous evidence from wild animals has been criticized for both applying anticonservative statistical tests and failing to consider random genetic drift. Here we study life-history variation in an insular preindustrial French-Canadian population and apply a recently proposed conservative approach to testing microevolutionary responses to selection. As reported for other such societies, natural selection favored an earlier age at first reproduction (AFR) among women. AFR was also highly heritable and genetically correlated to fitness, predicting a microevolutionary change toward earlier reproduction. In agreement with this prediction, AFR declined from about 26-22 y over a 140-y period. Crucially, we uncovered a substantial change in the breeding values for this trait, indicating that the change in AFR largely occurred at the genetic level. Moreover, the genetic trend was higher than expected under the effect of random genetic drift alone. Our results show that microevolution can be detectable over relatively few generations in humans and underscore the need for studies of human demography and reproductive ecology to consider the role of evolutionary processes.

  9. ["Artificial animals etc." Popular natural history and bourgeois curiosity around 1900].

    PubMed

    Wessely, Christina

    2008-01-01

    During the 19th and early 20th century zoological gardens ranged among the most prominent places of popular natural history While aristocratic owners of earlier menageries installed animal collections mostly to symbolize their power over nature as well as to display their extensive diplomatic relations, the zoological gardens founded from the 1830s onwards all over Europe by members of the local bourgeois elites were supposed to mediate their social and political values by "enjoyably educating" a broader public. The new zoos were introduced as places at the antipodes of the frenzy, noise and motion of modern urban life, as spaces of pure, authentic nature whose observation would teach people a reasonable and responsible way of life in a civilised bourgeois community. Taking the Berlin Zoo as an example this paper questions these programmatic imaginations by showing how popular Naturkunde (natural history) was informed by cultures of urban entertainment and spectacle. It discusses the numerous relations and productive tensions that evolved out of the establishment of a "realm of nature" in the middle of the ever growing modern metropolis and investigates the consequences the zoo's rise as "the city's most important attraction" around the turn of the century had for the public perception of natural history as well as for the institution's scientific program.

  10. The domestic cat as a natural animal model of Alzheimer's disease.

    PubMed

    Chambers, James K; Tokuda, Takahiko; Uchida, Kazuyuki; Ishii, Ryotaro; Tatebe, Harutsugu; Takahashi, Erika; Tomiyama, Takami; Une, Yumi; Nakayama, Hiroyuki

    2015-12-10

    Alzheimer's disease (AD) is the most dominant neurodegenerative disorder that causes dementia, and no effective treatments are available. To study its pathogenesis and develop therapeutics, animal models representing its pathologies are needed. Although many animal species develop senile plaques (SP) composed of amyloid-β (Aβ) proteins that are identical to those found in humans, none of them exhibit neurofibrillary tangles (NFT) and subsequent neurodegeneration, which are integral parts of the pathology of AD. The present study shows that Aβ accumulation, NFT formation, and significant neuronal loss all emerge naturally in the hippocampi of aged domestic cats. The NFT that form in the cat brain are identical to those seen in human AD in terms of their spatial distribution, the cells they affect, and the tau isoforms that comprise them. Interestingly, aged cats do not develop mature argyrophilic SP, but instead accumulate intraneuronal Aβ oligomers in their hippocampal pyramidal cells, which might be due to the amino acid sequence of felid Aβ. These results suggest that Aβ oligomers are more important than SP for NFT formation and the subsequent neurodegeneration. The domestic cat is a unique animal species that naturally replicates various AD pathologies, especially Aβ oligomer accumulation, NFT formation, and neuronal loss.

  11. Translational pain assessment: could natural animal models be the missing link?

    PubMed

    Klinck, Mary P; Mogil, Jeffrey S; Moreau, Maxim; Lascelles, B Duncan X; Flecknell, Paul A; Poitte, Thierry; Troncy, Eric

    2017-09-01

    Failure of analgesic drugs in clinical development is common. Along with the current "reproducibility crisis" in pain research, this has led some to question the use of animal models. Experimental models tend to comprise genetically homogeneous groups of young, male rodents in restricted and unvarying environments, and pain-producing assays that may not closely mimic the natural condition of interest. In addition, typical experimental outcome measures using thresholds or latencies for withdrawal may not adequately reflect clinical pain phenomena pertinent to human patients. It has been suggested that naturally occurring disease in veterinary patients may provide more valid models for the study of painful disease. Many painful conditions in animals resemble those in people. Like humans, veterinary patients are genetically diverse, often live to old age, and enjoy a complex environment, often the same as their owners. There is increasing interest in the development and validation of outcome measures for detecting pain in veterinary patients; these include objective (eg, locomotor activity monitoring, kinetic evaluation, quantitative sensory testing, and bioimaging) and subjective (eg, pain scales and quality of life scales) measures. Veterinary subject diversity, pathophysiological similarities to humans, and diverse outcome measures could yield better generalizability of findings and improved translation potential, potentially benefiting both humans and animals. The Comparative Oncology Trial Consortium in dogs has pawed the way for translational research, surmounting the challenges inherent in veterinary clinical trials. This review describes numerous conditions similarly applicable to pain research, with potential mutual benefits for human and veterinary clinicians, and their respective patients.

  12. Selecting appropriate animal models and experimental designs for endocrine disruptor research and testing studies.

    PubMed

    Stokes, William S

    2004-01-01

    Evidence that chemicals in the environment may cause developmental and reproductive abnormalities in fish and wildlife by disrupting normal endocrine functions has increased concern about potential adverse human health effects from such chemicals. US laws have now been enacted that require the US Environmental Protection Agency (EPA) to develop and validate a screening program to identify chemicals in food and water with potential endocrine-disrupting activity. EPA subsequently proposed an Endocrine Disruptor Screening Program that uses in vitro and in vivo test systems to identify chemicals that may adversely affect humans and ecologically important animal species. However, the endocrine system can be readily modulated by many experimental factors, including diet and the genetic background of the selected animal strain or stock. It is therefore desirable to minimize or avoid factors that cause or contribute to experimental variation in endocrine disruptor research and testing studies. Standard laboratory animal diets contain high and variable levels of phytoestrogens, which can modulate physiologic and behavioral responses similar to both endogenous estrogen as well as exogenous estrogenic chemicals. Other studies have determined that some commonly used outbred mice and rats are less responsive to estrogenic substances than certain inbred mouse and rat strains for various estrogen-sensitive endpoints. It is therefore critical to select appropriate biological models and diets for endocrine disruptor studies that provide optimal sensitivity and specificity to accomplish the research or testing objectives. An introduction is provided to 11 other papers in this issue that review these and other important laboratory animal experimental design considerations in greater detail, and that review laboratory animal and in vitro models currently being used or evaluated for endocrine disruptor research and testing. Selection of appropriate animal models and experimental design

  13. Darwinian fitness and the intensity of natural selection: studies in sensitivity analysis.

    PubMed

    Demetrius, Lloyd; Matthias Gundlach, Volker; Ziehe, Martin

    2007-12-21

    Darwinian fitness, the capacity of a variant type to establish itself in competition with the resident population, is determined by evolutionary entropy, a measure of the uncertainty in age of the mother of a randomly chosen newborn. This article shows that the intensity of natural selection, as measured by the sensitivity of entropy with respect to changes in the age-specific fecundity and mortality variables, is a convex function of age, decreasing at early and increasing at later ages. We exploit this result to provide quantitative evolutionary explanations of the large variation in survivorship curves observed in natural populations. Previous studies to explain variation in survivorship curves have been based on the proposition that Darwinian fitness is determined by the Malthusian parameter. Hence the intensity of natural selection will be determined by the sensitivity of the Malthusian parameter with respect to changes in the age-specific fecundity and mortality variables. This measure of the selection gradient is known to be a decreasing function of age, with implications which are inconsistent with empirical observations of survivorship curves in human and animal populations. The analysis described in this paper point to the mitigated import of sensitivity studies based on the Malthusian parameter. Our analysis provides theoretical and empirical support for the ecological and evolutionary significance of sensitivity analysis based on entropy, which is the appropriate measure of Darwinian fitness.

  14. Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation.

    PubMed

    Colautti, Robert I; Lau, Jennifer A

    2015-05-01

    Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. © 2015 John Wiley & Sons Ltd.

  15. Natural and sexual selection in a wild insect population.

    PubMed

    Rodríguez-Muñoz, R; Bretman, A; Slate, J; Walling, C A; Tregenza, T

    2010-06-04

    The understanding of natural and sexual selection requires both field and laboratory studies to exploit the advantages and avoid the disadvantages of each approach. However, studies have tended to be polarized among the types of organisms studied, with vertebrates studied in the field and invertebrates in the lab. We used video monitoring combined with DNA profiling of all of the members of a wild population of field crickets across two generations to capture the factors predicting the reproductive success of males and females. The factors that predict a male's success in gaining mates differ from those that predict how many offspring he has. We confirm the fundamental prediction that males vary more in their reproductive success than females, and we find that females as well as males leave more offspring when they mate with more partners.

  16. [Erythrocytes of hetero- and homoiothermal animals in natural and artificial hypothermia].

    PubMed

    Lomako, V V; Shilo, A V; Kovalenko, I F; Babiĭchuk, G A

    2015-01-01

    By the low-angle light scattering technique there are revealed peculiarities of dynamics of transformation (osmotic fragility, level of hemolysis and ratio of forms by index of sphericity) of erythrocytes of hetero- (golden hamsters Mesocricetus auratus) and homoiothermal (white rats Rattus norbegicus) animals in natural hibernation and suspended animation, craniocerebral and immersion hypothermia. In control in hamsters the osmotic fragility and the level of hemolysis of erythrocytes were higher than in rats, predominant were modified forms (in particular stomatocytes). Under artificial hypothermia, regardless of the way of achievement, depth and duration, we observed changes similar in direction, but different in expression: the osmotic fragility and hemolysis increased, the portion of discocytes decreased (especially sharply in hamsters under suspended animation), the number of changed erythrocytic forms rose. In contrast, under hiberation the osmotic fragility, hemolysis and the amount of stomatocytes declined, the portion of discocytes increased, but at the same time the amount of prehemolytic forms (spherocytes) rose too. In 24 hs there occurred a decrease of osmotic fragility (after suspended animation more pronounced in hamsters) and the level of hemolysis (especially after immersion hypothermia), the portion of discocytes was restored, in hamsters after suspended animation and in rats after immersion hypothermia it even exceeded the control level; spherocytes in blood of hamsters were not revealed, in rats they were elevated. Possibly, the observed qualitative change of population of spherocytes 24 h after hypothermia toward its homogeneity is determined not only at the level of elimination of old and defected cells, activation of erythropoiesis, the appearance of highly resistant erythrocytes, but also at the level of time membrane-stabilizing mechanisms.

  17. [The carnivorous fungi hyphomycetes are natural regulators of the size of animal parasitic nematodes].

    PubMed

    Tepliakova, T V; Efremova, E A; Riabchikova, E I

    2005-01-01

    The carnivorous fungi hyphomycetes are natural enemies of soil nematodes. Laboratory tests examining the effect of the effective strain Duddingtonia flagrans T-89 on equine strongyle larvae have indicated that their size can be reduced 5-48-fold under the action of the fungus. Using helminth-infected mice as an example has ascertained that when the animals are fed a biopreparation, the chlamydial spores of the carnivorous fungus D. flagrans remain viable and continue their development in the excrements. The dead nematodes show cell structural impairments in all tissues and organs, which may be associated with the action of the substances contained in the cell envelope of the fungus.

  18. Novel peptide chemistry in terrestrial animals: natural luciferin analogues from the bioluminescent earthworm Fridericia heliota.

    PubMed

    Dubinnyi, Maxim A; Tsarkova, Aleksandra S; Petushkov, Valentin N; Kaskova, Zinaida M; Rodionova, Natalja S; Kovalchuk, Sergey I; Ziganshin, Rustam H; Baranov, Mikhail S; Mineev, Konstantin S; Yampolsky, Ilia V

    2015-03-02

    We report isolation and structure elucidation of AsLn5, AsLn7, AsLn11 and AsLn12: novel luciferin analogs from the bioluminescent earthworm Fridericia heliota. They were found to be highly unusual modified peptides, comprising either of the two tyrosine-derived chromophores, CompX or CompY and a set of amino acids, including threonine, gamma-aminobutyric acid, homoarginine, and unsymmetrical N,N-dimethylarginine. These natural compounds represent a unique peptide chemistry found in terrestrial animals and rise novel questions concerning their biosynthetic origin. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. [Script animation: a method for describing and replicating natural human movements].

    PubMed

    Kempter, G

    1999-01-01

    Script-animation, a new method for prototypically describing and replicating natural movements of the human body, is introduced in this paper. The principal elements are the technique for producing scripts of behavior through biomechanical taxonomy, and the digital interface, which feeds the positional codes to the respective body structures of a computer doll. Illustrating the new method, all gestural movements from 59 political leaders as they appeared in TV-broadcasts news were reanimated on a simple doll. 84 subjects viewed the original sequences and 36 subjects viewed the reanimations. Simultaneously, the psychophysiological responses of the subjects were recorded. A comparison of physiological parameters shows high similarity in vegetative judgement.

  20. Effects of selected bioactive natural products on the vascular endothelium.

    PubMed

    Ahmad, Ajaz; Khan, Rao M A; Alkharfy, Khalid M

    2013-08-01

    The endothelium, a highly active structure, regulates vascular homeostasis through the release of numerous vasoactive factors that control vascular tone and vascular smooth cell proliferation. A larger number of medicinal plants and their isolated chemical constituents have been shown to beneficially affect the endothelium. For example, flavonoids in black tea, green tea, and concord grape cause a vasodilation possibly through their antioxidant properties. Allicin, a by-product of the enzyme alliinase, has been proposed to be the main active metabolite and responsible for most of the biological activities of garlic, including a dose-dependent dilation on the isolated coronaries. Thymoquinone, the principal phytochemical compound found in the volatile oil of the black seed, and the hawthorn extract have also been shown to improve aging-related impairment of endothelium-dependent relaxations in animal models. In this review, the effect of some of the natural products, including Camellia sinensis (black tea and green tea), Vitis labrusca (concord grape), Allium sativum (garlic), and Nigella sativa (black seed) and Crataegus ssp (hawthorn extract), is explored. The molecular mechanisms behind these potential therapeutic effects are also discussed.

  1. Natural Selection on Fecundity Variance in Subdivided Populations: Kin Selection Meets Bet Hedging

    PubMed Central

    Lehmann, Laurent; Balloux, François

    2007-01-01

    In a series of seminal articles in 1974, 1975, and 1977, J. H. Gillespie challenged the notion that the “fittest” individuals are those that produce on average the highest number of offspring. He showed that in small populations, the variance in fecundity can determine fitness as much as mean fecundity. One likely reason why Gillespie's concept of within-generation bet hedging has been largely ignored is the general consensus that natural populations are of large size. As a consequence, essentially no work has investigated the role of the fecundity variance on the evolutionary stable state of life-history strategies. While typically large, natural populations also tend to be subdivided in local demes connected by migration. Here, we integrate Gillespie's measure of selection for within-generation bet hedging into the inclusive fitness and game theoretic measure of selection for structured populations. The resulting framework demonstrates that selection against high variance in offspring number is a potent force in large, but structured populations. More generally, the results highlight that variance in offspring number will directly affect various life-history strategies, especially those involving kin interaction. The selective pressures on three key traits are directly investigated here, namely within-generation bet hedging, helping behaviors, and the evolutionary stable dispersal rate. The evolutionary dynamics of all three traits are markedly affected by variance in offspring number, although to a different extent and under different demographic conditions. PMID:17339208

  2. Selection against inbred song sparrows during a natural population bottleneck.

    PubMed

    Keller, L F; Arcese, P; Smith, J N; Hochachka, W M; Stearns, S C

    1994-11-24

    The genetic and demographic consequences of population subdivision have received considerable attention from conservation biologists. In particular, losses of genetic variability and reduced viability and fecundity due to inbreeding (inbreeding depression) are of concern. Studies of domestic, laboratory and zoo populations have shown inbreeding depression in a variety of traits related to fitness. Consequently, inbreeding depression is widely accepted as a fact. Recently, however, the relative impact of inbreeding on the viability of natural populations has been questioned. Work on the cheetah (Acinonyx jubatus), for example, has emphasized the overwhelming importance of environmental factors on mortality in the wild. Here we report that song sparrows (Melospiza melodia) that survived a severe population bottleneck were a non-random subset of the pre-crash population with respect to inbreeding, and that natural selection favoured outbred individuals. Thus, inbreeding depression was expressed in the face of an environmental challenge. Such challenges are also likely to be faced by inbred populations of endangered species. We suggest that environmental and genetic effects on survival may interact and, as a consequence, that their effects on individuals and populations should not be considered independently.

  3. Mixed strategies and natural selection in resource allocation.

    PubMed

    Kareva, Irina; Berezovkaya, Faina; Karev, Georgy

    2013-01-01

    An appropriate choice of strategy for resource allocation may frequently determine whether a population will be able to survive under the conditions of severe resource limitations. Here we focus on two classes of strategies allocation of resources towards rapid proliferation, or towards slower proliferation but increased physiological and environmental maintenance. We propose a generalized framework, where individuals within a population can use either strategy in different proportion for utilization of a common dynamical resource in order to maximize their fitness. We use the model to address two major questions, namely, whether either strategy is more likely to be selected for as a result of natural selection, and, if one allows for the possibility of resource over-consumption, whether either strategy is preferable for avoiding population collapse due to resource exhaustion. Analytical and numerical results suggest that the ultimate choice of strategy is determined primarily by the initial distribution of individuals in the population, and that while investment in physiological and environmental maintenance is a preferable strategy in a homogeneous population, no generalized prediction can be made about heterogeneous populations.

  4. Thermodynamics of natural selection II: Chemical Carnot cycles.

    PubMed

    Smith, Eric

    2008-05-21

    This is the second in a series of three papers devoted to energy flow and entropy changes in chemical and biological processes, and to their relations to the thermodynamics of computation. In the first paper of the series, it was shown that a general-form dimensional argument from the second law of thermodynamics captures a number of scaling relations governing growth and development across many domains of life. It was also argued that models of physiology based on reversible transformations provide sensible approximations within which the second-law scaling is realized. This paper provides a formal basis for decomposing general cyclic, fixed-temperature chemical reactions, in terms of the chemical equivalent of Carnot's cycle for heat engines. It is shown that the second law relates the minimal chemical work required to perform a cycle to the Kullback-Leibler divergence produced in its chemical output ensemble from that of a Gibbs equilibrium. Reversible models of physiology are used to create reversible models of natural selection, which relate metabolic energy requirements to information gain under optimal conditions. When dissipation is added to models of selection, the second-law constraint is generalized to a relation between metabolic work and the combined energies of growth and maintenance.

  5. Spatially-Correlated Risk in Nature Reserve Site Selection

    PubMed Central

    Albers, Heidi J.; Busby, Gwenlyn M.; Hamaide, Bertrand; Ando, Amy W.; Polasky, Stephen

    2016-01-01

    Establishing nature reserves protects species from land cover conversion and the resulting loss of habitat. Even within a reserve, however, many factors such as fires and defoliating insects still threaten habitat and the survival of species. To address the risk to species survival after reserve establishment, reserve networks can be created that allow some redundancy of species coverage to maximize the expected number of species that survive in the presence of threats. In some regions, however, the threats to species within a reserve may be spatially correlated. As examples, fires, diseases, and pest infestations can spread from a starting point and threaten neighboring parcels’ habitats, in addition to damage caused at the initial location. This paper develops a reserve site selection optimization framework that compares the optimal reserve networks in cases where risks do and do not reflect spatial correlation. By exploring the impact of spatially-correlated risk on reserve networks on a stylized landscape and on an Oregon landscape, this analysis demonstrates an appropriate and feasible method for incorporating such post-reserve establishment risks in the reserve site selection literature as an additional tool to be further developed for future conservation planning. PMID:26789127

  6. Spatially-Correlated Risk in Nature Reserve Site Selection.

    PubMed

    Albers, Heidi J; Busby, Gwenlyn M; Hamaide, Bertrand; Ando, Amy W; Polasky, Stephen

    2016-01-01

    Establishing nature reserves protects species from land cover conversion and the resulting loss of habitat. Even within a reserve, however, many factors such as fires and defoliating insects still threaten habitat and the survival of species. To address the risk to species survival after reserve establishment, reserve networks can be created that allow some redundancy of species coverage to maximize the expected number of species that survive in the presence of threats. In some regions, however, the threats to species within a reserve may be spatially correlated. As examples, fires, diseases, and pest infestations can spread from a starting point and threaten neighboring parcels' habitats, in addition to damage caused at the initial location. This paper develops a reserve site selection optimization framework that compares the optimal reserve networks in cases where risks do and do not reflect spatial correlation. By exploring the impact of spatially-correlated risk on reserve networks on a stylized landscape and on an Oregon landscape, this analysis demonstrates an appropriate and feasible method for incorporating such post-reserve establishment risks in the reserve site selection literature as an additional tool to be further developed for future conservation planning.

  7. Natural Selection for Operons Depends on Genome Size

    PubMed Central

    Nuñez, Pablo A.; Romero, Héctor; Farber, Marisa D.; Rocha, Eduardo P.C.

    2013-01-01

    In prokaryotes, genome size is associated with metabolic versatility, regulatory complexity, effective population size, and horizontal transfer rates. We therefore analyzed the covariation of genome size and operon conservation to assess the evolutionary models of operon formation and maintenance. In agreement with previous results, intraoperonic pairs of essential and of highly expressed genes are more conserved. Interestingly, intraoperonic pairs of genes are also more conserved when they encode proteins at similar cell concentrations, suggesting a role of cotranscription in diminishing the cost of waste and shortfall in gene expression. Larger genomes have fewer and smaller operons that are also less conserved. Importantly, lower conservation in larger genomes was observed for all classes of operons in terms of gene expression, essentiality, and balanced protein concentration. We reached very similar conclusions in independent analyses of three major bacterial clades (α- and β-Proteobacteria and Firmicutes). Operon conservation is inversely correlated to the abundance of transcription factors in the genome when controlled for genome size. This suggests a negative association between the complexity of genetic networks and operon conservation. These results show that genome size and/or its proxies are key determinants of the intensity of natural selection for operon organization. Our data fit better the evolutionary models based on the advantage of coregulation than those based on genetic linkage or stochastic gene expression. We suggest that larger genomes with highly complex genetic networks and many transcription factors endure weaker selection for operons than smaller genomes with fewer alternative tools for genetic regulation. PMID:24201372

  8. Natural selection for costly nutrient recycling in simulated microbial metacommunities.

    PubMed

    Boyle, Richard A; Williams, Hywel T P; Lenton, Timothy M

    2012-11-07

    Recycling of essential nutrients occurs at scales from microbial communities to global biogeochemical cycles, often in association with ecological interactions in which two or more species utilise each others' metabolic by-products. However, recycling loops may be unstable; sequences of reactions leading to net recycling may be parasitised by side-reactions causing nutrient loss, while some reactions in any closed recycling loop are likely to be costly to participants. Here we examine the stability of nutrient recycling loops in an individual-based ecosystem model based on microbial functional types that differ in their metabolism. A supplied nutrient is utilised by a "source" functional type, generating a secondary nutrient that is subsequently used by two other types-a "mutualist" that regenerates the initial nutrient at a growth rate cost, and a "parasite" that produces a refractory waste product but does not incur any additional cost. The three functional types are distributed across a metacommunity in which separate patches are linked by a stochastic diffusive migration process. Regions of high mutualist abundance feature high levels of nutrient recycling and increased local population density leading to greater export of individuals, allowing the source-mutualist recycling loop to spread across the system. Individual-level selection favouring parasites is balanced by patch-level selection for high productivity, indirectly favouring mutualists due to the synergistic productivity benefits of the recycling loop they support. This suggests that multi-level selection may promote nutrient cycling and thereby help to explain the apparent ubiquity and stability of nutrient recycling in nature.

  9. Natural selection on individual variation in tolerance of gastrointestinal nematode infection.

    PubMed

    Hayward, Adam D; Nussey, Daniel H; Wilson, Alastair J; Berenos, Camillo; Pilkington, Jill G; Watt, Kathryn A; Pemberton, Josephine M; Graham, Andrea L

    2014-07-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host-parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites.

  10. Natural Selection on Individual Variation in Tolerance of Gastrointestinal Nematode Infection

    PubMed Central

    Hayward, Adam D.; Nussey, Daniel H.; Wilson, Alastair J.; Berenos, Camillo; Pilkington, Jill G.; Watt, Kathryn A.; Pemberton, Josephine M.; Graham, Andrea L.

    2014-01-01

    Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host–parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites. PMID:25072883

  11. Minipig and beagle animal model genomes aid species selection in pharmaceutical discovery and development

    SciTech Connect

    Vamathevan, Jessica J.; Hall, Matthew D.; Hasan, Samiul; Woollard, Peter M.; Xu, Meng; Yang, Yulan; Li, Xin; Wang, Xiaoli; Kenny, Steve; Brown, James R.; Huxley-Jones, Julie; Lyon, Jon; Haselden, John; Min, Jiumeng; Sanseau, Philippe

    2013-07-15

    Improving drug attrition remains a challenge in pharmaceutical discovery and development. A major cause of early attrition is the demonstration of safety signals which can negate any therapeutic index previously established. Safety attrition needs to be put in context of clinical translation (i.e. human relevance) and is negatively impacted by differences between animal models and human. In order to minimize such an impact, an earlier assessment of pharmacological target homology across animal model species will enhance understanding of the context of animal safety signals and aid species selection during later regulatory toxicology studies. Here we sequenced the genomes of the Sus scrofa Göttingen minipig and the Canis familiaris beagle, two widely used animal species in regulatory safety studies. Comparative analyses of these new genomes with other key model organisms, namely mouse, rat, cynomolgus macaque, rhesus macaque, two related breeds (S. scrofa Duroc and C. familiaris boxer) and human reveal considerable variation in gene content. Key genes in toxicology and metabolism studies, such as the UGT2 family, CYP2D6, and SLCO1A2, displayed unique duplication patterns. Comparisons of 317 known human drug targets revealed surprising variation such as species-specific positive selection, duplication and higher occurrences of pseudogenized targets in beagle (41 genes) relative to minipig (19 genes). These data will facilitate the more effective use of animals in biomedical research. - Highlights: • Genomes of the minipig and beagle dog, two species used in pharmaceutical studies. • First systematic comparative genome analysis of human and six experimental animals. • Key drug toxicology genes display unique duplication patterns across species. • Comparison of 317 drug targets show species-specific evolutionary patterns.

  12. More than Meets the Eye--a Simulation of Natural Selection.

    ERIC Educational Resources Information Center

    Allen, J. A.; And Others

    1987-01-01

    Presents experiments using wild birds as predators and pastry as prey and colored stones as background to demonstrate natural selection. Describes the exercise as an exercise in simulating natural selection. (Author/CW)

  13. More than Meets the Eye--a Simulation of Natural Selection.

    ERIC Educational Resources Information Center

    Allen, J. A.; And Others

    1987-01-01

    Presents experiments using wild birds as predators and pastry as prey and colored stones as background to demonstrate natural selection. Describes the exercise as an exercise in simulating natural selection. (Author/CW)

  14. Edge co-occurrences can account for rapid categorization of natural versus animal images

    NASA Astrophysics Data System (ADS)

    Perrinet, Laurent U.; Bednar, James A.

    2015-06-01

    Making a judgment about the semantic category of a visual scene, such as whether it contains an animal, is typically assumed to involve high-level associative brain areas. Previous explanations require progressively analyzing the scene hierarchically at increasing levels of abstraction, from edge extraction to mid-level object recognition and then object categorization. Here we show that the statistics of edge co-occurrences alone are sufficient to perform a rough yet robust (translation, scale, and rotation invariant) scene categorization. We first extracted the edges from images using a scale-space analysis coupled with a sparse coding algorithm. We then computed the “association field” for different categories (natural, man-made, or containing an animal) by computing the statistics of edge co-occurrences. These differed strongly, with animal images having more curved configurations. We show that this geometry alone is sufficient for categorization, and that the pattern of errors made by humans is consistent with this procedure. Because these statistics could be measured as early as the primary visual cortex, the results challenge widely held assumptions about the flow of computations in the visual system. The results also suggest new algorithms for image classification and signal processing that exploit correlations between low-level structure and the underlying semantic category.

  15. Radiation prevulcanized natural rubber latex: Cytotoxicity and safety evaluation on animal

    NASA Astrophysics Data System (ADS)

    Keong, C. C.; Zin, W. M. Wan; Ibrahim, P.; Ibrahim, S.

    2010-05-01

    Radiation prevulcanized natural rubber latex (RVNRL) was claimed to be more user friendly than natural rubber latex prevulcanized by sulphur curing system. The absence of Type IV allergy inducing chemicals in RVNRL make it a suitable material for manufacturing of many kinds of latex products, especially those come into direct contact with users. This paper reveals and discusses the findings of cytotoxicity test and safety evaluation on animal for RVNRL. The test was done on RVNRL films prepared by coagulant dipping method and RVNRL dipped products produced by latex dipped product manufacturers. Cytotocixity test was carried out on mammalian cell culture American Type Culture Collection CCL 81, Vero. Results indicated that no cytotoxic effect from RVNRL films and products was found on the cell culture. Two animal studies, namely dermal sensitization study and primary skin irritation study, were done on gloves made from RVNRL. Albino white guinea pigs were used as test subjects in dermal sensitization study and results showed no sensitization induced by the application of test material in the guinea pigs. Primary skin irritation study was done on New Zealand white rabbits and results showed that the product tested was not corrosive and was not a primary irritant

  16. Senescence in natural populations of animals: Widespread evidence and its implications for bio-gerontology

    PubMed Central

    Nussey, Daniel H.; Froy, Hannah; Lemaitre, Jean-François; Gaillard, Jean-Michel; Austad, Steve N.

    2014-01-01

    That senescence is rarely, if ever, observed in natural populations is an oft-quoted fallacy within bio-gerontology. We identify the roots of this fallacy in the otherwise seminal works of Medawar and Comfort, and explain that under antagonistic pleiotropy or disposable soma explanations for the evolution of senescence there is no reason why senescence cannot evolve to be manifest within the life expectancies of wild organisms. The recent emergence of long-term field studies presents irrefutable evidence that senescence is commonly detected in nature. We found such evidence in 175 different animal species from 340 separate studies. Although the bulk of this evidence comes from birds and mammals, we also found evidence for senescence in other vertebrates and insects. We describe how high-quality longitudinal field data allow us to test evolutionary explanations for differences in senescence between the sexes and among traits and individuals. Recent studies indicate that genes, prior environment and investment in growth and reproduction influence aging rates in the wild. We argue that – with the fallacy that wild animals do not senesce finally dead and buried – collaborations between bio-gerontologists and field biologists can begin to test the ecological generality of purportedly ‘public’ mechanisms regulating aging in laboratory models. PMID:22884974

  17. Multi-mycotoxin analysis of animal feed and animal-derived food using LC-MS/MS system with timed and highly selective reaction monitoring.

    PubMed

    Zhao, Zhiyong; Liu, Na; Yang, Lingchen; Deng, Yifeng; Wang, Jianhua; Song, Suquan; Lin, Shanhai; Wu, Aibo; Zhou, Zhenlei; Hou, Jiafa

    2015-09-01

    Mycotoxins have the potential to enter the human food chain through carry-over of contaminants from feed into animal-derived products. The objective of the study was to develop a reliable and sensitive method for the analysis of 30 mycotoxins in animal feed and animal-derived food (meat, edible animal tissues, and milk) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the study, three extraction procedures, as well as various cleanup procedures, were evaluated to select the most suitable sample preparation procedure for different sample matrices. In addition, timed and highly selective reaction monitoring on LC-MS/MS was used to filter out isobaric matrix interferences. The performance characteristics (linearity, sensitivity, recovery, precision, and specificity) of the method were determined according to Commission Decision 2002/657/EC and 401/2006/EC. The established method was successfully applied to screening of mycotoxins in animal feed and animal-derived food. The results indicated that mycotoxin contamination in feed directly influenced the presence of mycotoxin in animal-derived food. Graphical abstract Multi-mycotoxin analysis of animal feed and animal-derived food using LC-MS/MS.

  18. Immunology (1955-1975): the natural selection theory, the two signal hypothesis and positive repertoire selection.

    PubMed

    Forsdyke, Donald R

    2012-01-01

    Observations suggesting the existence of natural antibody prior to exposure of an organism to the corresponding antigen, led to the natural selection theory of antibody formation of Jerne in 1955, and to the two signal hypothesis of Forsdyke in 1968. Aspects of these were not only first discoveries but also foundational discoveries in that they influenced contemporaries in a manner that, from our present vantage point, appears to have been constructive. Jerne's later hypothesis (1971, European Journal of Immunology 1: 1-9), that antibody-like receptors on lymphocytes were selected over evolutionary time for reactivity with the major histocompatibility complex (MHC) antigens of the species, was a first, but it was incorrect, and was foundational only to the extent that it emphasized the need to explain the Simonsen phenomenon. Although easily construed as derivative of Jerne (1971), the affinity/avidity model of Forsdyke (1975, Journal of Theoretical Biology 52: 187-198), which predicted that cell-surface components, including MHC antigens, would restrict antigen-reactivity by somatically shaping lymphocyte repertoires, was actually an extension of the two signal hypothesis. While presenting a mechanism for the positive selection of lymphocyte repertoires, and explaining the Simonsen phenomenon, the affinity/avidity model was not foundational in that it had to be independently rediscovered. For science to advance optimally we must seek to close temporal gaps so that first discoveries are also foundational. Listening to young scientists may be part of the solution.

  19. Contributions of natural and sexual selection to the evolution of premating reproductive isolation: a research agenda.

    PubMed

    Safran, Rebecca J; Scordato, Elizabeth S C; Symes, Laurel B; Rodríguez, Rafael L; Mendelson, Tamra C

    2013-11-01

    Speciation by divergent natural selection is well supported. However, the role of sexual selection in speciation is less well understood due to disagreement about whether sexual selection is a mechanism of evolution separate from natural selection, as well as confusion about various models and tests of sexual selection. Here, we outline how sexual selection and natural selection are different mechanisms of evolutionary change, and suggest that this distinction is critical when analyzing the role of sexual selection in speciation. Furthermore, we clarify models of sexual selection with respect to their interaction with ecology and natural selection. In doing so, we outline a research agenda for testing hypotheses about the relative significance of divergent sexual and natural selection in the evolution of reproductive isolation.

  20. Transient Fecal Shedding and Limited Animal-to-Animal Transmission of Clostridium difficile by Naturally Infected Finishing Feedlot Cattle ▿

    PubMed Central

    Rodriguez-Palacios, Alexander; Pickworth, Carrie; Loerch, Steve; LeJeune, Jeffrey T.

    2011-01-01

    To longitudinally assess fecal shedding and animal-to-animal transmission of Clostridium difficile among finishing feedlot cattle as a risk for beef carcass contamination, we tested 186 ± 12 steers (mean ± standard deviation; 1,369 samples) in an experimental feedlot facility during the finishing period and at harvest. Clostridium difficile was isolated from 12.9% of steers on arrival (24/186; 0 to 33% among five suppliers). Shedding decreased to undetectable levels a week later (0%; P < 0.001), and remained low (<3.6%) until immediately prior to shipment for harvest (1.2%). Antimicrobial use did not increase fecal shedding, despite treatment of 53% of animals for signs of respiratory disease. Animals shedding C. difficile on arrival, however, had 4.6 times higher odds of receiving antimicrobials for respiratory signs than nonshedders (95% confidence interval for the odds ratio, 1.4 to 14.8; P = 0.01). Neither the toxin genes nor toxin A or B was detected in most (39/42) isolates based on two complementary multiplex PCRs and enzyme-linked immunosorbent assay testing, respectively. Two linezolid- and clindamycin-resistant PCR ribotype 078 (tcdA+/tcdB+/cdtB+/39-bp-type deletion in tcdC) isolates were identified from two steers (at arrival and week 20), but these ribotypes did not become endemic. The other toxigenic isolate (tcdA+/tcdB+/cdtB+/classic tcdC; PCR ribotype 078-like) was identified in the cecum of one steer at harvest. Spatio-temporal analysis indicated transient shedding with no evidence of animal-to-animal transmission. The association between C. difficile shedding upon arrival and the subsequent need for antimicrobials for respiratory disease might indicate common predisposing factors. The isolation of toxigenic C. difficile from bovine intestines at harvest highlights the potential for food contamination in meat processing plants. PMID:21441320

  1. Effects of natural and sexual selection on adaptive population divergence and premating isolation in a damselfly.

    PubMed

    Svensson, Erik I; Eroukhmanoff, Fabrice; Friberg, Magne

    2006-06-01

    The relative strength of different types of directional selection has seldom been compared directly in natural populations. A recent meta-analysis of phenotypic selection studies in natural populations suggested that directional sexual selection may be stronger in magnitude than directional natural selection, although this pattern may have partly been confounded by the different time scales over which selection was estimated. Knowledge about the strength of different types of selection is of general interest for understanding how selective forces affect adaptive population divergence and how they may influence speciation. We studied divergent selection on morphology in parapatric, natural damselfly (Calopteryx splendens) populations. Sexual selection was stronger than natural selection measured on the same traits, irrespective of the time scale over which sexual selection was measured. Visualization of the fitness surfaces indicated that population divergence in overall morphology is more strongly influenced by divergent sexual selection rather than natural selection. Courtship success of experimental immigrant males was lower than that of resident males, indicating incipient sexual isolation between these populations. We conclude that current and strong sexual selection promotes adaptive population divergence in this species and that premating sexual isolation may have arisen as a correlated response to divergent sexual selection. Our results highlight the importance of sexual selection, rather than natural selection in the adaptive radiation of odonates, and supports previous suggestions that divergent sexual selection promotes speciation in this group.

  2. Selecting suitable sites for animal waste application using a raster GIS.

    PubMed

    Basnet, B B; Apan, A A; Raine, S R

    2001-10-01

    Rapid growth of intensive animal industries in southeast Queensland, Australia, has led to large volumes of animal waste production, which possess serious environmental problems in the Murray Darling Basin (MDB). This study presents a method of selecting sites for the safe application of animal waste as fertiliser to agricultural land. A site suitability map for the Westbrook subcatchment within the MDB was created using a geographic information system (GIS)-based weighted linear combination (WLC) model. The factors affecting the suitability of a site for animal waste application were selected, and digital data sets derived from up to 1:50,000 scale maps were acquired. After initial preprocessing, digital data sets were clipped to the size of the delineated subcatchment boundary producing input factors. These input factors were weighted using the analytical hierarchy process (AHP) that employed an objectives-oriented comparison (OOC) technique to formulate the pairwise comparison matrix. The OOC technique, which is capable of deriving factor weight independently, formulated the weight derivation process by making it more logical and systematic. The factor attributes were classified into multiple classes and weighted using the AHP. The effects of the number of input factors and factor weighting on the areal extent and the degree of site suitability were examined. Due to the presence of large nonagricultural and residential areas in the subcatchment, only 16% of the area was found suitable for animal waste application. The areal extent resulting from this site suitability assessment was found to be dependent on the areal constraints imposed on each input factor, while the degree of suitability was principally a function of the weight distribution between the factors.

  3. Estimating animal resource selection from telemetry data using point process models.

    PubMed

    Johnson, Devin S; Hooten, Mevin B; Kuhn, Carey E

    2013-11-01

    1. Analyses of animal resource selection functions (RSF) using data collected from relocations of individuals via remote telemetry devices have become commonplace. Increasing technological advances, however, have produced statistical challenges in analysing such highly autocorrelated data. Weighted distribution methods have been proposed for analysing RSFs with telemetry data. However, they can be computationally challenging due to an intractable normalizing constant and cannot be aggregated (i.e. collapsed) over time to make space-only inference. 2. In this study, we take a conceptually different approach to modelling animal telemetry data for making RSF inference. We consider the telemetry data to be a realization of a space-time point process. Under the point process paradigm, the times of the relocations are also considered to be random rather than fixed. 3. We show the point process models we propose are a generalization of the weighted distribution telemetry models. By generalizing the weighted model, we can access several numerical techniques for evaluating point process likelihoods that make use of common statistical software. Thus, the analysis methods can be readily implemented by animal ecologists. 4. In addition to ease of computation, the point process models can be aggregated over time by marginalizing over the temporal component of the model. This allows a full range of models to be constructed for RSF analysis at the individual movement level up to the study area level. 5. To demonstrate the analysis of telemetry data with the point process approach, we analysed a data set of telemetry locations from northern fur seals (Callorhinus ursinus) in the Pribilof Islands, Alaska. Both a space-time and an aggregated space-only model were fitted. At the individual level, the space-time analysis showed little selection relative to the habitat covariates. However, at the study area level, the space-only model showed strong selection relative to the covariates

  4. Using DNA Barcodes to Identify Road-Killed Animals in Two Atlantic Forest Nature Reserves, Brazil

    PubMed Central

    Klippel, Angélica H.; Oliveira, Pablo V.; Britto, Karollini B.; Freire, Bárbara F.; Moreno, Marcel R.; dos Santos, Alexandre R.; Banhos, Aureo; Paneto, Greiciane G.

    2015-01-01

    Road mortality is the leading source of biodiversity loss in the world, especially due to fragmentation of natural habitats and loss of wildlife. The survey of the main species victims of roadkill is of fundamental importance for the better understanding of the problem, being necessary, for this, the correct species identification. The aim of this study was to verify if DNA barcodes can be applied to identify road-killed samples that often cannot be determined morphologically. For this purpose, 222 vertebrate samples were collected in a stretch of the BR-101 highway that crosses two Discovery Coast Atlantic Forest Natural Reserves, the Sooretama Biological Reserve and the Vale Natural Reserve, in Espírito Santo, Brazil. The mitochondrial COI gene was amplified, sequenced and confronted with the BOLD database. It was possible to identify 62.16% of samples, totaling 62 different species, including Pyrrhura cruentata, Chaetomys subspinosus, Puma yagouaroundi and Leopardus wiedii considered Vulnerable in the National Official List of Species of Endangered Wildlife. The most commonly identified animals were a bat (Molossus molossus), an opossum (Didelphis aurita) and a frog (Trachycephalus mesophaeus) species. Only one reptile was identified using the technique, probably due to lack of reference sequences in BOLD. These data may contribute to a better understanding of the impact of roads on species biodiversity loss and to introduce the DNA barcode technique to road ecology scenarios. PMID:26244644

  5. Using DNA Barcodes to Identify Road-Killed Animals in Two Atlantic Forest Nature Reserves, Brazil.

    PubMed

    Klippel, Angélica H; Oliveira, Pablo V; Britto, Karollini B; Freire, Bárbara F; Moreno, Marcel R; Dos Santos, Alexandre R; Banhos, Aureo; Paneto, Greiciane G

    2015-01-01

    Road mortality is the leading source of biodiversity loss in the world, especially due to fragmentation of natural habitats and loss of wildlife. The survey of the main species victims of roadkill is of fundamental importance for the better understanding of the problem, being necessary, for this, the correct species identification. The aim of this study was to verify if DNA barcodes can be applied to identify road-killed samples that often cannot be determined morphologically. For this purpose, 222 vertebrate samples were collected in a stretch of the BR-101 highway that crosses two Discovery Coast Atlantic Forest Natural Reserves, the Sooretama Biological Reserve and the Vale Natural Reserve, in Espírito Santo, Brazil. The mitochondrial COI gene was amplified, sequenced and confronted with the BOLD database. It was possible to identify 62.16% of samples, totaling 62 different species, including Pyrrhura cruentata, Chaetomys subspinosus, Puma yagouaroundi and Leopardus wiedii considered Vulnerable in the National Official List of Species of Endangered Wildlife. The most commonly identified animals were a bat (Molossus molossus), an opossum (Didelphis aurita) and a frog (Trachycephalus mesophaeus) species. Only one reptile was identified using the technique, probably due to lack of reference sequences in BOLD. These data may contribute to a better understanding of the impact of roads on species biodiversity loss and to introduce the DNA barcode technique to road ecology scenarios.

  6. Maintenance of an aminopeptidase allele frequency cline by natural selection.

    PubMed Central

    Koehn, R K; Newell, R I; Immermann, F

    1980-01-01

    The product of the Lap locus in the marine bivalve Mytilus edulis is a neutral, membrane-associated aminopeptidase that is primarily localized on intestinal microvilli and in digestive cell lysosomes. Natural populations are genetically differentiated at the Lap locus between areas of differing salinity. A steep (0.55-0.15) allele frequency cline connects differentiated populations between the Atlantic Ocean and Long Island Sound. We demonstrate an annual gene flow/mortality cycle in cline populations whereby gene frequencies after mortality are correlated with salinity and enzyme activity. The cline is spatially and temporally unstable in immigrants, but stable in residents after mortality. Mortality is nonrandom with regard to the Lap locus; genotype-dependent properties of the aminopeptidase enzyme apparently led to a differential rate of the utilizaiton of nutrient reserves because selected genotypes exhibited an increased rate of tissue weight loss. Aminopeptidase genotypes are differentially adapted to different temperatures and salinities, which provides a mechanism for the relationship among biochemical, physiological, and population phenotypes. PMID:6933563

  7. Selective Chemical Labeling of Natural T Modifications in DNA

    PubMed Central

    2015-01-01

    We present a chemical method to selectively tag and enrich thymine modifications, 5-formyluracil (5-fU) and 5-hydroxymethyluracil (5-hmU), found naturally in DNA. Inherent reactivity differences have enabled us to tag 5-fU chemoselectively over its C modification counterpart, 5-formylcytosine (5-fC). We rationalized the enhanced reactivity of 5-fU compared to 5-fC via ab initio quantum mechanical calculations. We exploited this chemical tagging reaction to provide proof of concept for the enrichment of 5-fU containing DNA from a pool that contains 5-fC or no modification. We further demonstrate that 5-hmU can be chemically oxidized to 5-fU, providing a strategy for the enrichment of 5-hmU. These methods will enable the mapping of 5-fU and 5-hmU in genomic DNA, to provide insights into their functional role and dynamics in biology. PMID:25946119

  8. The use of marker-assisted selection in animal breeding and biotechnology.

    PubMed

    Williams, J L

    2005-04-01

    Improvement of livestock has focused on the selective breeding of individuals with superior phenotypes. With the development of increasingly advanced statistical methods that maximise selection for genetic gain, this simple approach has been extremely successful in increasing the quantity of agricultural output. However, information now available on the organisation and functioning of the genome could be used in breeding programmes to improve a range of traits. Many traits are under the control of several genetic loci, each of which contribute to the variation in the trait and hence are called quantitative trait loci (QTL). While genetic markers for QTL that are linked to the trait gene could be used to choose animals for selective breeding programmes, the most effective markers are the functional mutations within the trait genes. Strategies to identify markers for traits and the application of these markers are described by reference to examples of loci that control a range of different traits.

  9. Disease Risk Assessments Involving Companion Animals: an Overview for 15 Selected Pathogens Taking a European Perspective.

    PubMed

    Rijks, J M; Cito, F; Cunningham, A A; Rantsios, A T; Giovannini, A

    2016-07-01

    Prioritization of companion animal transmissible diseases was performed by the Companion Animals multisectoriaL interprofessionaL Interdisciplinary Strategic Think tank On zoonoses (CALLISTO) project. The project considered diseases occurring in domesticated species commonly kept as pets, such as dogs and cats, but also included diseases occurring in captive wild animals and production animal species. The prioritization process led to the selection of 15 diseases of prime public health relevance, agricultural economic importance, or both. An analysis was made of the current knowledge on the risk of occurrence and transmission of these diseases among companion animals, and from companion animals to man (zoonoses) or to livestock. The literature was scanned for risk assessments for these diseases. Studies were classified as import risk assessments (IRAs) or risk factor analyses (RFAs) in endemic areas. For those pathogens that are absent from Europe, only IRAs were considered; for pathogens present throughout Europe, only RFAs were considered. IRAs were identified for seven of the eight diseases totally or partially absent from Europe. IRAs for classical rabies and alveolar echinococcosis found an increased risk for introduction of the pathogen into officially disease-free areas as a consequence of abandoning national rules and adopting the harmonized EU rules for pet travel. IRAs for leishmaniosis focused on risk associated with the presence of persistently infected dogs in new geographical areas, taking into consideration the risk of disease establishment should a competent vector arise. IRAs for Crimean-Congo haemorrhagic fever and West Nile fever indicated that the likelihood of introduction via companion animals was low. IRAs for bluetongue paid no attention to the risk of introduction via companion animals, which was also the case for IRAs for foot-and-mouth disease, the only disease considered to be absent from Europe. RFAs dealing with the risk factors for

  10. Ecological factors drive natural selection pressure of avian aryl hydrocarbon receptor 1 genotypes

    PubMed Central

    Hwang, Ji-Hee; Park, Jin-Young; Park, Hae-Jeong; Bak, Su-Min; Hirano, Masashi; Iwata, Hisato; Park, Young-Suk; Kim, Eun-Young

    2016-01-01

    The aryl hydrocarbon receptor (AHR) mediates dioxin toxicities. Several studies have suggested that two amino acid residues corresponding to the 324th and 380th positions in the ligand binding domain (LBD) of the chicken AHR1 (Ile_Ser as high sensitivity, Ile_Ala as moderate sensitivity, and Val_Ala as low sensitivity), could be an important factor determining dioxin sensitivity in avian species. Here, we analyzed the association between ecological factors and AHR1 LBD genotypes of 113 avian species. Cluster analyses showed that 2 major clusters and sub-clusters of the cluster 3 were associated with specific AHR1 genotypes depending on the food, habitat, and migration of the animal. The majority of the species with Ile_Ala type were the Passeriformes, which are omnivorous or herbivorous feeders in the terrestrial environment. The species with Val_Ala type was primarily composed of raptors and waterbirds, which have been exposed to naturally occurring dioxins. An in vitro reporter gene assay revealed that the sensitivity to a natural dioxin, 1,3,7-tribromodibenzo-p-dioxin was in the order of Ile_Ser > Ile_Ala > Val_Ala. These results suggest that ecological factors related to the exposure of natural dioxins contribute to natural selection of the avian AHR1 genotype, which consequently leads to different sensitivity to man-made dioxins. PMID:27283192

  11. Animal movement constraints improve resource selection inference in the presence of telemetry error

    USGS Publications Warehouse

    Brost, Brian M.; Hooten, Mevin B.; Hanks, Ephraim M.; Small, Robert J.

    2016-01-01

    Multiple factors complicate the analysis of animal telemetry location data. Recent advancements address issues such as temporal autocorrelation and telemetry measurement error, but additional challenges remain. Difficulties introduced by complicated error structures or barriers to animal movement can weaken inference. We propose an approach for obtaining resource selection inference from animal location data that accounts for complicated error structures, movement constraints, and temporally autocorrelated observations. We specify a model for telemetry data observed with error conditional on unobserved true locations that reflects prior knowledge about constraints in the animal movement process. The observed telemetry data are modeled using a flexible distribution that accommodates extreme errors and complicated error structures. Although constraints to movement are often viewed as a nuisance, we use constraints to simultaneously estimate and account for telemetry error. We apply the model to simulated data, showing that it outperforms common ad hoc approaches used when confronted with measurement error and movement constraints. We then apply our framework to an Argos satellite telemetry data set on harbor seals (Phoca vitulina) in the Gulf of Alaska, a species that is constrained to move within the marine environment and adjacent coastlines.

  12. [Thinking and practice of animal ethology in study of cold and hot nature of traditional Chinese medicine].

    PubMed

    Xing, Xiaoyan; Zhao, Yanling; Kong, Weijun; Jia, Lei; Wang, Jiabo; Yan, Dan; Li, Ruisheng; Xiao, Xiaohe

    2011-02-01

    From the view of macroscopic animal ethology combined with computer and modem image processing technique, by monitoring the temperature tropism of animal affected by traditional Chinese medicine (TCM) with different Cold and Hot natures and obtaining many behavior parameters which were difficult to assess in direct observation, the differences between the Cold and Hot nature of TCM were evaluated and presented. This method could real-time, intuitively and objectively, qualitatively and quantitatively monitor the temperature tropism of experimental animals with no disturbance. Further, the Cold and Hot nature of TCM can be expressed from the whole animal level. This method met to the application peculiarity of TCM and suited for the TCM theoretical system. It is a attempt for the study of drug nature of TCM. It also contributed to elucidate the objective authenticity and scientific connotation of Cold and Hot nature of TCM, and express the inherent connection of this nature and the temperature tropism of animal. In this review, a new point and technology platform was provided for establishing an objective method for evaluating the Cold and Hot nature of TCM, which are corresponding with the feature of the application of TCM.

  13. Studying human respiratory disease in animals--role of induced and naturally occurring models.

    PubMed

    Williams, Kurt; Roman, Jesse

    2016-01-01

    Respiratory disorders like asthma, emphysema, and pulmonary fibrosis affect millions of Americans and many more worldwide. Despite advancements in medical research that have led to improved understanding of the pathophysiology of these conditions and sometimes to new therapeutic interventions, these disorders are for the most part chronic and progressive; current interventions are not curative and do not halt disease progression. A major obstacle to further advancements relates to the absence of animal models that exactly resemble the human condition, which delays the elucidation of relevant mechanisms of action, the unveiling of biomarkers of disease progression, and identification of new targets for intervention in patients. There are currently many induced animal models of human respiratory disease available for study, and even though they mimic features of human disease, discoveries in these models have not always translated into safe and effective treatments in humans. A major obstacle relates to the genetic, anatomical, and functional variations amongst species, which represents the major challenge to overcome when searching for appropriate models of respiratory disease. Nevertheless, rodents, in particular mice, have become the most common species used for experimentation, due to their relatively low cost, size, and adequate understanding of murine genetics, among other advantages. Less well known is the fact that domestic animals also suffer from respiratory illnesses similar to those found in humans. Asthma, bronchitis, pneumonia, and pulmonary fibrosis are among the many disorders occurring naturally in dogs, cats, and horses, among other species. These models might better resemble the human condition and are emphasized here, but further investigations are needed to determine their relevance.

  14. Natural Non-Trasgenic Animal Models for Research in Alzheimer’s Disease

    PubMed Central

    Sarasa, Manuel; Pesini, Pedro

    2009-01-01

    The most common animal models currently used for Alzheimer disease (AD) research are transgenic mice that express a mutant form of human Aβ precursor protein (APP) and/or some of the enzymes implicated in their metabolic processing. However, these transgenic mice carry their own APP and APP-processing enzymes, which may interfere in the production of different amyloid-beta (Aβ) peptides encoded by the human transgenes. Additionally, the genetic backgrounds of the different transgenic mice are a possible confounding factor with regard to crucial aspects of AD that they may (or may not) reproduce. Thus, although the usefulness of transgenic mice is undisputed, we hypothesized that additional relevant information on the physiopathology of AD could be obtained from other natural non-transgenic models. We have analyzed the chick embryo and the dog, which may be better experimental models because their enzymatic machinery for processing APP is almost identical to that of humans. The chick embryo is extremely easy to access and manipulate. It could be an advantageous natural model in which to study the cell biology and developmental function of APP and a potential assay system for drugs that regulate APP processing. The dog suffers from an age-related syndrome of cognitive dysfunction that naturally reproduces key aspects of AD including Aβ cortical pathology, neuronal degeneration and learning and memory disabilities. However, dense core neuritic plaques and neurofibrillary tangles have not been consistently demonstrated in the dog. Thus, these species may be natural models with which to study the biology of AD, and could also serve as assay systems for Aβ-targeted drugs or new therapeutic strategies against this devastating disease. PMID:19355852

  15. Impact and Influence of the Natural Vibrio-Squid Symbiosis in Understanding Bacterial–Animal Interactions

    PubMed Central

    Mandel, Mark J.; Dunn, Anne K.

    2016-01-01

    Animals are colonized by bacteria, and in many cases partners have co-evolved to perform mutually beneficial functions. An exciting and ongoing legacy of the past decade has been an expansion of technology to enable study of natural associations in situ/in vivo. As a result, more symbioses are being examined, and additional details are being revealed for well-studied systems with a focus on the interactions between partners in the native context. With this framing, we review recent literature from the Vibrio fischeri–Euprymna scolopes symbiosis and focus on key studies that have had an impact on understanding bacteria–animal interactions broadly. This is not intended to be a comprehensive review of the system, but rather to focus on particular studies that have excelled at moving from pattern to process in facilitating an understanding of the molecular basis to intriguing observations in the field of host–microbe interactions. In this review we discuss the following topics: processes regulating strain and species specificity; bacterial signaling to host morphogenesis; multiple roles for nitric oxide; flagellar motility and chemotaxis; and efforts to understand unannotated and poorly annotated genes. Overall these studies demonstrate how functional approaches in vivo in a tractable system have provided valuable insight into general principles of microbe–host interactions. PMID:28018314

  16. Impact and Influence of the Natural Vibrio-Squid Symbiosis in Understanding Bacterial-Animal Interactions.

    PubMed

    Mandel, Mark J; Dunn, Anne K

    2016-01-01

    Animals are colonized by bacteria, and in many cases partners have co-evolved to perform mutually beneficial functions. An exciting and ongoing legacy of the past decade has been an expansion of technology to enable study of natural associations in situ/in vivo. As a result, more symbioses are being examined, and additional details are being revealed for well-studied systems with a focus on the interactions between partners in the native context. With this framing, we review recent literature from the Vibrio fischeri-Euprymna scolopes symbiosis and focus on key studies that have had an impact on understanding bacteria-animal interactions broadly. This is not intended to be a comprehensive review of the system, but rather to focus on particular studies that have excelled at moving from pattern to process in facilitating an understanding of the molecular basis to intriguing observations in the field of host-microbe interactions. In this review we discuss the following topics: processes regulating strain and species specificity; bacterial signaling to host morphogenesis; multiple roles for nitric oxide; flagellar motility and chemotaxis; and efforts to understand unannotated and poorly annotated genes. Overall these studies demonstrate how functional approaches in vivo in a tractable system have provided valuable insight into general principles of microbe-host interactions.

  17. Parallel shifts in ecology and natural selection in an island lizard.

    PubMed

    Calsbeek, Ryan; Buermann, Wolfgang; Smith, Thomas B

    2009-01-06

    Natural selection is a potent evolutionary force that shapes phenotypic variation to match ecological conditions. However, we know little about the year-to-year consistency of selection, or how inter-annual variation in ecology shapes adaptive landscapes and ultimately adaptive radiations. Here we combine remote sensing data, field experiments, and a four-year study of natural selection to show that changes in vegetation structure associated with a severe drought altered both habitat use and natural selection in the brown anole, Anolis sagrei. In natural populations, lizards increased their use of vegetation in wet years and this was correlated with selection on limb length but not body size. By contrast, a die-back of vegetation caused by drought was followed by reduced arboreality, selection on body size, and relaxed selection on limb length. With the return of the rains and recovery of vegetation, selection reverted back to pre-drought pattern of selection acting on limb length but not body size. To test for the impact of vegetation loss on natural selection during the drought, we experimentally removed vegetation on a separate study island in a naturally wet year. The experiment revealed similar inter-annual changes in selection on body size but not limb length. Our results illustrate the dynamic nature of ecology driving natural selection on Anolis morphology and emphasize the importance of inter-annual environmental variation in shaping adaptive variation. In addition, results illustrate the utility of using remote sensing data to examine ecology's role in driving natural selection.

  18. Unique educational methods to improve the veterinary employment selection process for rural mixed-animal practices.

    PubMed

    White, Brad J; Gwinner, Kevin P; Andrus, David M; Prince, J Bruce

    2007-01-01

    The rural mixed-animal veterinarian is a critical control point for safe, wholesome, affordable food production and security. The population of students entering food-animal practice is decreasing, and future shortages are likely. Veterinary practice owners will continue to struggle to find associates to fill open positions. Identifying and hiring the correct veterinarian for an open position is a challenging proposition for the rural practitioner. Kansas State University hosted a forum to facilitate the hiring process and provide education regarding the mechanism of an effective selection interview. A unique experiential technique known as "speed interviews" was used to facilitate communication between conference participants and to practice newly acquired skills. A survey of participants revealed similar viewpoints toward most job attributes. Veterinary students and prospective employers expressed realistic expectations of job requirements, salaries, and debt load. Students expressed willingness to work and desire to practice in the types of practices defined by the veterinarians. The symposium provided valuable insight for practitioners and students regarding the recruitment process. Appropriate and accurate representation at the time of job/associate selection is critical for long-term success and employee retention. The goal of the event was to provide a service to both prospective employers and students by offering education regarding the employment selection interview process and placing attendees in an environment rich with people who have complimentary goals.

  19. Selective breeding for differential saccharin intake as an animal model of drug abuse.

    PubMed

    Carroll, Marilyn E; Morgan, Andrew D; Anker, Justin J; Perry, Jennifer L; Dess, Nancy K

    2008-09-01

    A positive relationship between the consumption of sweetened dietary substances (e.g. saccharin and sucrose) and drug abuse has been reported in both the human and other animal literature. The proposed genetic contribution to this relationship has been based on evidence from behavioral, neurobiological, and linkage studies in heterogeneous and homogeneous animal populations. Initial work in several laboratories indicated that rodents that are selected for high alcohol consumption also display an increased preference for sweets compared with low alcohol-consuming animals. More recently, Sprague-Dawley rats have been selectively bred based on high saccharin (HiS) or low saccharin (LoS) consumption, and these lines represent an ideal opportunity to determine whether a reciprocal genetic relationship exists between the consumption of sweetened substances and self-administration of drugs of abuse. The purpose of this review is to examine a series of studies on the HiS and LoS rats for drug-seeking and drug-taking behavior using laboratory animal models that represent critical phases of drug abuse in humans. The data support the hypothesis that sweet consumption and drug self-administration are closely related and genetically influenced. Other characteristics of HiS and LoS rats are discussed as possible mediators of the genetic differences such as activity, impulsivity, novelty reactivity, stress, and emotionality. The interaction of sweet preference with biological variables related to drug abuse, such as age, sex, and hormonal influences, was considered, as they may be additive vulnerability factors with consumption of sweet substances. In the studies that are discussed, the HiS and LoS lines emerge as ideal addiction-prone and addiction-resistant models, respectively, with vulnerability or resilience factors that will inform prevention and treatment strategies for drug abuse.

  20. Human fertility, molecular genetics, and natural selection in modern societies.

    PubMed

    Tropf, Felix C; Stulp, Gert; Barban, Nicola; Visscher, Peter M; Yang, Jian; Snieder, Harold; Mills, Melinda C

    2015-01-01

    Research on genetic influences on human fertility outcomes such as number of children ever born (NEB) or the age at first childbirth (AFB) has been solely based on twin and family-designs that suffer from problematic assumptions and practical limitations. The current study exploits recent advances in the field of molecular genetics by applying the genomic-relationship-matrix based restricted maximum likelihood (GREML) methods to quantify for the first time the extent to which common genetic variants influence the NEB and the AFB of women. Using data from the UK and the Netherlands (N = 6,758), results show significant additive genetic effects on both traits explaining 10% (SE = 5) of the variance in the NEB and 15% (SE = 4) in the AFB. We further find a significant negative genetic correlation between AFB and NEB in the pooled sample of -0.62 (SE = 0.27, p-value = 0.02). This finding implies that individuals with genetic predispositions for an earlier AFB had a reproductive advantage and that natural selection operated not only in historical, but also in contemporary populations. The observed postponement in the AFB across the past century in Europe contrasts with these findings, suggesting an evolutionary override by environmental effects and underscoring that evolutionary predictions in modern human societies are not straight forward. It emphasizes the necessity for an integrative research design from the fields of genetics and social sciences in order to understand and predict fertility outcomes. Finally, our results suggest that we may be able to find genetic variants associated with human fertility when conducting GWAS-meta analyses with sufficient sample size.

  1. The Fundamental Theorem of Natural Selection in Ewens' Sense (Case of Fertility Selection)

    PubMed Central

    Lessard, S.; Castilloux, A. M.

    1995-01-01

    We show that the Fundamental Theorem of Natural Selection in Ewens' sense is valid in the case of fertility selection: the additive genetic variance in fertility divided by the mean fertility is exactly equal to the partial change in the mean fertility from the current generation to the next. This partial change is the increase in the mean additive value caused by frequency changes from one generation to the next but keeping unchanged the additive values. The only hypothesis on mating is that it does not affect the allelic frequencies in the sense that these are the same before and after mating in the parental generation, which occurs for a wide range of mating patterns going from random mating to several regular systems of inbreeding and cases of assortative mating. The fertility of couples is determined by the genes at an arbitrary number of loci, and the additive (average) allelic effects are defined by a linear system of equations, which is used to extend Ewens' optimality principle to the case of fertility selection. PMID:8647406

  2. "Everything Has to Die One Day:" Children's Explorations of the Meanings of Death in Human-Animal-Nature Relationships

    ERIC Educational Resources Information Center

    Russell, Joshua

    2017-01-01

    Children's experiences of death are a potentially vital component of their developing sense of relatedness to non-human others and nature. Environmental education theory and practice would benefit from a broader understanding of how children view death and loss within ecological systems as well as within human-animal-nature relationships, but such…

  3. "Everything Has to Die One Day:" Children's Explorations of the Meanings of Death in Human-Animal-Nature Relationships

    ERIC Educational Resources Information Center

    Russell, Joshua

    2017-01-01

    Children's experiences of death are a potentially vital component of their developing sense of relatedness to non-human others and nature. Environmental education theory and practice would benefit from a broader understanding of how children view death and loss within ecological systems as well as within human-animal-nature relationships, but such…

  4. The Origin of Mutants Under Selection: How Natural Selection Mimics Mutagenesis (Adaptive Mutation)

    PubMed Central

    Maisnier-Patin, Sophie; Roth, John R.

    2015-01-01

    Selection detects mutants but does not cause mutations. Contrary to this dictum, Cairns and Foster plated a leaky lac mutant of Escherichia coli on lactose medium and saw revertant (Lac+) colonies accumulate with time above a nongrowing lawn. This result suggested that bacteria might mutagenize their own genome when growth is blocked. However, this conclusion is suspect in the light of recent evidence that revertant colonies are initiated by preexisting cells with multiple copies the conjugative F′lac plasmid, which carries the lac mutation. Some plated cells have multiple copies of the simple F′lac plasmid. This provides sufficient LacZ activity to support plasmid replication but not cell division. In nongrowing cells, repeated plasmid replication increases the likelihood of a reversion event. Reversion to lac+ triggers exponential cell growth leading to a stable Lac+ revertant colony. In 10% of these plated cells, the high-copy plasmid includes an internal tandem lac duplication, which provides even more LacZ activity—sufficient to support slow growth and formation of an unstable Lac+ colony. Cells with multiple copies of the F′lac plasmid have an increased mutation rate, because the plasmid encodes the error-prone (mutagenic) DNA polymerase, DinB. Without DinB, unstable and stable Lac+ revertant types form in equal numbers and both types arise with no mutagenesis. Amplification and selection are central to behavior of the Cairns–Foster system, whereas mutagenesis is a system-specific side effect or artifact caused by coamplification of dinB with lac. Study of this system has revealed several broadly applicable principles. In all populations, gene duplications are frequent stable genetic polymorphisms, common near-neutral mutant alleles can gain a positive phenotype when amplified under selection, and natural selection can operate without cell division when variability is generated by overreplication of local genome subregions. PMID:26134316

  5. Possible role of different animal species in maintenance and spread of murine gammaherpesvirus 68 in the nature.

    PubMed

    Wágnerová, M; Chalupková, A; Hrabovská, Z; Ančicová, L; Mistríková, J

    2015-03-01

    Murine gammaherpesvirus 68 (MHV-68), isolated from a bank vole (Clethrionomys glareolus) in Slovakia in 1976 is a natural pathogen of wild murid rodents. This review is focused to biological properties of this pathogen, the mode of its maintenance in murid rodents as reservoir animals, mechanisms of its spread to other animals in the same biotope as well as to livestock and household animals. Potential role of ticks as vectors and the possibility of infection of humans with this virus are considered as well. All the above evidence of the virus infection of various hosts is based on serological or molecular analytical data. The presented knowledge indicates important epizootologic consequences, namely harboring and permanent maintenance of the virus in murid rodents as reservoir animals with a real possibility of spread to other animals in the same biotope. These relationships imply a cross-species virus transmission with potential serious consequences for the infected animals or humans.

  6. Kin-selected cooperation without lifetime monogamy: human insights and animal implications.

    PubMed

    Kramer, Karen L; Russell, Andrew F

    2014-11-01

    Recent phylogenetic analyses suggest that monogamy precedes the evolution of cooperative breeding involving non-breeding helpers. The rationale: only through monogamy can helper-recipient relatedness coefficients match those of parent-offspring. Given that humans are cooperative breeders, these studies imply a monogamy bottleneck during hominin evolution. However, evidence from multiple sources is not compelling. In reconciliation, we propose that selection against cooperative breeding under alternative mating patterns will be mitigated by: (i) kin discrimination, (ii) reduced birth-intervals, and (iii) constraints on independent breeding, particularly for premature and post-fertile individuals. We suggest that such alternatives require consideration to derive a complete picture of the selection pressures acting on the evolution of cooperative breeding in humans and other animals.

  7. [Serotonin receptors in the brain of animals selected for their domesticated type of behavior].

    PubMed

    Maslova, G B; Avgustinovich, D F

    1989-01-01

    Participation was studied of central serotonin receptors of the first and second types in behaviour change of animals selected by the character of defensive reaction to man. Serotonin receptors were determined by radioligand method by binding of the brain preparations 3H-serotonin and 3H-spiperone. An increase of C2 receptors number was found in the frontal brain cortex of the tame brown rats in comparison with the aggressive ones. Differences were not found in specific C1-receptor binding in the frontal brain cortex of tame and aggressive brown rats, silver foxes and American minks in various relatively early selection stages. It is supposed that disappearance of aggressive reaction to man at domestication is connected with an increase of C2 receptors number.

  8. Kin selection and the evolution of social information use in animal conflict.

    PubMed

    Baker, Christopher C M; Dall, Sasha R X; Rankin, Daniel J

    2012-01-01

    Animals often use social information about conspecifics in making decisions about cooperation and conflict. While the importance of kin selection in the evolution of intraspecific cooperation and conflict is widely acknowledged, few studies have examined how relatedness influences the evolution of social information use. Here we specifically examine how relatedness affects the evolution of a stylised form of social information use known as eavesdropping. Eavesdropping involves individuals escalating conflicts with rivals observed to have lost their last encounter and avoiding fights with those seen to have won. We use a game theoretical model to examine how relatedness affects the evolution of eavesdropping, both when strategies are discrete and when they are continuous or mixed. We show that relatedness influences the evolution of eavesdropping, such that information use peaks at intermediate relatedness. Our study highlights the importance of considering kin selection when exploring the evolution of complex forms of information use.

  9. Tumor Selectivity of Oncolytic Parvoviruses: From in vitro and Animal Models to Cancer Patients

    PubMed Central

    Angelova, Assia L.; Geletneky, Karsten; Nüesch, Jürg P. F.; Rommelaere, Jean

    2015-01-01

    Oncolytic virotherapy of cancer is among the innovative modalities being under development and especially promising for targeting tumors, which are resistant to conventional treatments. Presently, at least a dozen of viruses, belonging to nine different virus families, are being tested within the frames of various clinical studies in cancer patients. Continuously growing preclinical evidence showing that the autonomous rat parvovirus H-1 (H-1PV) is able to kill tumor cells that resist conventional treatments and to achieve a complete cure of various human tumors in animal models argues for its inclusion in the arsenal of oncolytic viruses with an especially promising bench to bedside translation potential. Oncolytic parvovirus safe administration to humans relies on the intrinsic preference of these agents for quickly proliferating, metabolically, and biochemically disturbed tumor versus normal cells (tumor selectivity or oncotropism). The present review summarizes and discusses (i) preclinical evidence of H-1PV innocuousness for normal cells and healthy tissues in vitro and in animals, respectively, (ii) toxicological assessments of H-1PV mono- or combined therapy in tumor-bearing virus-permissive animal models, as well as (iii) historical results of experimental infection of human cancer patients with H-1PV. Altogether, these data argue against a risk of H-1PV inducing significant toxic effects in human patients. This highly favorable safety profile allowed the translation of H-1PV preclinical research into a Phase I/IIa clinical trial being currently in progress. PMID:25954743

  10. Prevalence of selected bacterial infections associated with the use of animal waste in Louisiana.

    PubMed

    Hill, Dagne D; Owens, William E; Tchounwou, Paul B

    2005-04-01

    Human health is a major concern when considering the disposal of large quantities of animal waste. Health concerns could arise from exposure to pathogens and excess nitrogen associated with this form of pollution. The objective was to collect and analyze health data related to selected bacterial infections associated with the use of animal waste in Louisiana. An analysis of adverse health effects has been conducted based on the incidence/prevalence rates of campylobacteriosis, E. coli O157:H7 infection, salmonellosis and shigellosis. The number of reported cases increased during the summer months. Analysis of health data showed that reported disease cases of E. coli O157:H7 were highest among Caucasian infants in the 0-4 year old age category and in Caucasian children in the 5-9 year old age category. Fatalities resulting from salmonellosis are low and increases sharply with age. The number of reported cases of shigellosis was found to be higher in African American males and females than in Caucasians. The high rate of identification in the younger population may result from the prompt seeking of medical care, as well as the frequent ordering of stool examination when symptoms become evident among this group of the population. The association with increasing age and fatality due to salmonellosis could be attributed to declining health and weaker immune systems often found in the older population. It is concluded that both animal waste and non-point source pollution may have a significant impact on human health.

  11. Toxicity of naturally-contaminated manganese soil to selected crops.

    PubMed

    Kováčik, Jozef; Štěrbová, Dagmar; Babula, Petr; Švec, Pavel; Hedbavny, Josef

    2014-07-23

    The impact of manganese excess using naturally contaminated soil (Mn-soil, pseudototal Mn 6494 vs 675 μg g(-1) DW in control soil) in the shoots of four crops was studied. Mn content decreased in the order Brassica napus > Hordeum vulgare > Zea mays > Triticum aestivum. Growth was strongly depressed just in Brassica (containing 13696 μg Mn g(-1) DW). Some essential metals (Zn, Fe) increased in Mn-cultured Brassica and Zea, while macronutrients (K, Ca, Mg) decreased in almost all species. Toxic metals (Ni and Cd) were rather elevated in Mn-soil. Microscopy of ROS, NO, lipid peroxidation, and thiols revealed stimulation in all Mn-cultured crops, but changes were less visible in Triticum, a species with low shoot Mn (2363 μg g(-1) DW). Antioxidative enzyme activities were typically enhanced in Mn-cultured plants. Soluble phenols increased in Brassica only while proteins rather decreased in response to Mn excess. Inorganic anions (chloride, sulfate, and phosphate) were less accumulated in almost all Mn-cultured crops, while the nitrate level rather increased. Organic anions (malate, citrate, oxalate, acetate, and formate) decreased or remained unaffected in response to Mn-soil culture in Brassica, Hordeum, and Triticum but not in Zea. However, the role of organic acids in Mn uptake in these species is not assumed. Because control and Mn-soil differed in pH (6.5 and 3.7), we further studied its impact on Mn uptake in solution culture (using Mn concentration ∼5 mM deducted from water-soluble fraction of Mn-soil). Shoot Mn contents in Mn-treated plants were similar to those observed in soil culture (high in Brassica and low in Triticum) and pH had negligible impact. Fluorescence indicator of "general ROS" revealed no extensive or pH-dependent impact either in control or Mn-cultured roots. Observed toxicity of Mn excess to common crops urges for selection of cultivars with higher tolerance.

  12. Natural selection reinforces speciation in a radiation of neotropical rainforest plants.

    PubMed

    Kay, Kathleen M; Schemske, Douglas W

    2008-10-01

    The importance of reinforcement, that is, natural selection that strengthens reproductive isolation between incipient species, remains controversial. We used two approaches to test for reinforcement in a species radiation of Neotropical gingers in the genus Costus. First, we conducted an intensive study of Costus pulverulentus and Costus scaber, two recently diverged species that co-occur and share hummingbird pollinators. The hummingbird pollinators transfer pollen between these Costus species, but hybrids are rarely found in nature. By performing pollinations between populations of C. pulverulentus and C. scaber from three sites across the species' geographic ranges, we find that pollen-pistil incompatibilities acting prior to fertilization have evolved only between locally sympatric populations, whereas geographically distant populations within the region of sympatry and allopatric populations remain fully interfertile. Second, we conducted a comparative study of isolating mechanisms across the genus. We find lower seed set due to pollen-pistil incompatibility between species pairs that co-occur and experience pollen transfer in nature compared to species pairs that are otherwise isolated, regardless of genetic distance. Taken together, these studies indicate that crossing barriers prevent potentially maladaptive hybridization and effectively reinforce the speciation process. Our results add to mounting evidence for reinforcement from animal studies and show that plant speciation may also involve complex mate recognition systems. Reinforcement may be particularly important in rapidly diverging lineages where ecological factors play a primary role in reproductive isolation, as may often be the case in tropical communities.

  13. Optimal energy window selection of a CZT-based small-animal SPECT for quantitative accuracy

    NASA Astrophysics Data System (ADS)

    Park, Su-Jin; Yu, A. Ram; Choi, Yun Young; Kim, Kyeong Min; Kim, Hee-Joung

    2015-05-01

    Cadmium zinc telluride (CZT)-based small-animal single-photon emission computed tomography (SPECT) has desirable characteristics such as superior energy resolution, but data acquisition for SPECT imaging has been widely performed with a conventional energy window. The aim of this study was to determine the optimal energy window settings for technetium-99 m (99mTc) and thallium-201 (201Tl), the most commonly used isotopes in SPECT imaging, using CZT-based small-animal SPECT for quantitative accuracy. We experimentally investigated quantitative measurements with respect to primary count rate, contrast-to-noise ratio (CNR), and scatter fraction (SF) within various energy window settings using Triumph X-SPECT. The two ways of energy window settings were considered: an on-peak window and an off-peak window. In the on-peak window setting, energy centers were set on the photopeaks. In the off-peak window setting, the ratios of energy differences between the photopeak from the lower- and higher-threshold varied from 4:6 to 3:7. In addition, the energy-window width for 99mTc varied from 5% to 20%, and that for 201Tl varied from 10% to 30%. The results of this study enabled us to determine the optimal energy windows for each isotope in terms of primary count rate, CNR, and SF. We selected the optimal energy window that increases the primary count rate and CNR while decreasing SF. For 99mTc SPECT imaging, the energy window of 138-145 keV with a 5% width and off-peak ratio of 3:7 was determined to be the optimal energy window. For 201Tl SPECT imaging, the energy window of 64-85 keV with a 30% width and off-peak ratio of 3:7 was selected as the optimal energy window. Our results demonstrated that the proper energy window should be carefully chosen based on quantitative measurements in order to take advantage of desirable characteristics of CZT-based small-animal SPECT. These results provided valuable reference information for the establishment of new protocol for CZT

  14. North American Natural Gas Markets: Selected technical studies

    SciTech Connect

    Huntington, H.G.; Schuler, G.E.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  15. North American Natural Gas Markets: Selected technical studies. Volume 3

    SciTech Connect

    Huntington, H.G.; Schuler, G.E.

    1989-04-01

    The Energy Modeling Forum (EMF) was established in 1976 at Stanford University to provide a structural framework within which energy experts, analysts, and policymakers could meet to improve their understanding of critical energy problems. The ninth EMF study, North American Natural Gas Markets, was conducted by a working group comprised of leading natural gas analysts and decision-makers from government, private companies, universities, and research and consulting organizations. The EMF 9 working group met five times from October 1986 through June 1988 to discuss key issues and analyze natural gas markets. This third volume includes technical papers that support many of the conclusions discussed in the EMF 9 summary report (Volume 1) and full working group report (Volume 2). These papers discuss the results from the individual models as well as some nonmodeling analysis related to US natural gas imports and industrial natural gas demand. Individual papers have been processed separately for inclusion in the Energy Science and Technology Database.

  16. Concurrent natural and sexual selection in wild male sockeye salmon, Oncorhynchus nerka.

    PubMed

    Hamon, Troy R; Foote, Chris J

    2005-05-01

    Concurrent natural and sexual selection have been inferred from laboratory and comparative studies in a number of taxa, but are rarely measured in natural populations. Because the interaction of these two general categories of selection may be complex when they occur simultaneously, empirical evidence from natural populations would help us to understand this interaction and probably give us greater insight into each separate episode as well. In male sockeye salmon, sexual selection for larger body size has been indicated in both deep and shallow water habitats. However, in shallow habitats male sockeye are generally smaller and less deep-bodied than in deep habitats, a difference that has been ascribed to natural selection. We measured concurrent natural and sexual selection in two years on breeding male sockeye salmon with respect to body size, body shape, and time of arrival to the breeding grounds. Natural selection was variable in effect and sexual selection was variable in intensity in these two years. The patterns of selection also appear to be interdependent; areas where predation on spawning adults is not intense have yielded different patterns of sexual selection than those measured here. It appears that some of the body shape differences in sockeye salmon associated with different spawning habitats, which were previously attributed to selective mortality, may be a result of different patterns of sexual selection in the different habitats. Total selection resulting from the combination of both natural and sexual selection was less intense than either natural or sexual selection in most cases. Measurement of concurrent selection episodes in nature may help us to understand whether the pattern of differential sexual selection is common, and whether observed patterns of habitat-related differentiation may be due to differences in sexual selection.

  17. Artificial selection for structural color on butterfly wings and comparison with natural evolution

    PubMed Central

    Wasik, Bethany R.; Liew, Seng Fatt; Lilien, David A.; Dinwiddie, April J.; Noh, Heeso; Cao, Hui; Monteiro, Antónia

    2014-01-01

    Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales’ structural color via slight modifications to the scales’ physical dimensions. PMID:25092295

  18. Artificial selection for structural color on butterfly wings and comparison with natural evolution.

    PubMed

    Wasik, Bethany R; Liew, Seng Fatt; Lilien, David A; Dinwiddie, April J; Noh, Heeso; Cao, Hui; Monteiro, Antónia

    2014-08-19

    Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related species and populations of Bicyclus butterflies have evolved violet structural color from brown-pigmented ancestors with UV structural color. We used artificial selection on a laboratory model butterfly, B. anynana, to evolve violet scales from UV brown scales and compared the mechanism of violet color production with that of two other Bicyclus species, Bicyclus sambulos and Bicyclus medontias, which have evolved violet/blue scales independently via natural selection. The UV reflectance peak of B. anynana brown scales shifted to violet over six generations of artificial selection (i.e., in less than 1 y) as the result of an increase in the thickness of the lower lamina in ground scales. Similar scale structures and the same mechanism for producing violet/blue structural colors were found in the other Bicyclus species. This work shows that populations harbor large amounts of standing genetic variation that can lead to rapid evolution of scales' structural color via slight modifications to the scales' physical dimensions.

  19. Selection of osteoprogenitors from the jaw periosteum by a specific animal-free culture medium.

    PubMed

    Alexander, Dorothea; Rieger, Melanie; Klein, Christian; Ardjomandi, Nina; Reinert, Siegmar

    2013-01-01

    The goal of our research work is to establish mesenchymal osteoprogenitors derived from human jaw periosteum for tissue engineering applications in oral and maxillofacial surgery. For future autologous and/or allogeneic transplantations, some issues must be addressed. On the one hand, animal-free culture conditions have yet to be established. On the other hand, attempts should be undertaken to shorten the in vitro culturing process efficiently. The aim of the present study is to compare and analyze the phenotype of osteoprogenitors from the jaw periosteum under normal FCS-containing and animal-free culture conditions. Therefore, we analyzed the proliferation rates of MesenCult-XF medium (MC-) in comparison to DMEM-cultured JPCs. Whereas jaw periosteal cells (JPCs) show relatively slow proliferation rates and a fibroblastoid shape under DMEM culture conditions, MC-cultured JPCs diminished their cell size significantly and proliferated rapidly. By live-monitoring measurements of adhesion and proliferation, we made an interesting observation: whereas the proliferation of the MSCA-1(+) subpopulation and the unseparated cell fraction were favored by the animal-free culture medium, the proliferation of the MSCA-1(-) subpopulation seemed to be repressed under these conditions. The alkaline phosphatase expression pattern showed similar results under both culture conditions. Comparison of the mineralization capacity revealed an earlier formation of calcium-phosphate precipitates under MC culture conditions; however, the mineralization capacity of the DMEM-cultured cells seemed to be higher. We conclude that the tested animal-free medium is suitable for the in vitro expansion and even for the specific selection of osteoprogenitor cells derived from the jaw periosteum.

  20. Natural habitats matter: Determinants of spatial pattern in the composition of animal assemblages of the Czech Republic

    NASA Astrophysics Data System (ADS)

    Divíšek, Jan; Zelený, David; Culek, Martin; Št'astný, Karel

    2014-08-01

    Studies that explore species-environment relationships at a broad scale are usually limited by the availability of sufficient habitat description, which is often too coarse to differentiate natural habitat patches. Therefore, it is not well understood how the distribution of natural habitats affects broad-scale patterns in the distribution of animal species. In this study, we evaluate the role of field-mapped natural habitats, land-cover types derived from remote sensing and climate on the composition of assemblages of five distinct animal groups, namely non-volant mammals, birds, reptiles, amphibians and butterflies native to the Czech Republic. First, we used variation partitioning based on redundancy analysis to evaluate the extent to which the environmental variables and their spatial structure might underlie the observed spatial patterns in the composition of animal assemblages. Second, we partitioned variations explained by climate, natural habitats and land-cover to compare their relative importance. Finally, we tested the independent effects of each variable in order to evaluate the significance of their contributions to the environmental model. Our results showed that spatial patterns in the composition of assemblages of almost all the considered animal groups may be ascribed mostly to variations in the environment. Although the shared effects of climatic variables, natural habitats and land-cover types explained the largest proportion of variation in each animal group, the variation explained purely by natural habitats was always higher than the variation explained purely by climate or land-cover. We conclude that most spatial variation in the composition of assemblages of almost all animal groups probably arises from biological processes operating within a spatially structured environment and suggest that natural habitats are important to explain observed patterns because they often perform better than habitat descriptions based on remote sensing. This

  1. Widespread genomic signatures of natural selection in hominid evolution.

    PubMed

    McVicker, Graham; Gordon, David; Davis, Colleen; Green, Phil

    2009-05-01

    Selection acting on genomic functional elements can be detected by its indirect effects on population diversity at linked neutral sites. To illuminate the selective forces that shaped hominid evolution, we analyzed the genomic distributions of human polymorphisms and sequence differences among five primate species relative to the locations of conserved sequence features. Neutral sequence diversity in human and ancestral hominid populations is substantially reduced near such features, resulting in a surprisingly large genome average diversity reduction due to selection of 19-26% on the autosomes and 12-40% on the X chromosome. The overall trends are broadly consistent with "background selection" or hitchhiking in ancestral populations acting to remove deleterious variants. Average selection is much stronger on exonic (both protein-coding and untranslated) conserved features than non-exonic features. Long term selection, rather than complex speciation scenarios, explains the large intragenomic variation in human/chimpanzee divergence. Our analyses reveal a dominant role for selection in shaping genomic diversity and divergence patterns, clarify hominid evolution, and provide a baseline for investigating specific selective events.

  2. Automated long-term tracking and social behavioural phenotyping of animal colonies within a semi-natural environment.

    PubMed

    Weissbrod, Aharon; Shapiro, Alexander; Vasserman, Genadiy; Edry, Liat; Dayan, Molly; Yitzhaky, Assif; Hertzberg, Libi; Feinerman, Ofer; Kimchi, Tali

    2013-01-01

    Social behaviour has a key role in animal survival across species, ranging from insects to primates and humans. However, the biological mechanisms driving natural interactions between multiple animals, over long-term periods, are poorly studied and remain elusive. Rigorous and objective quantification of behavioural parameters within a group poses a major challenge as it requires simultaneous monitoring of the positions of several individuals and comprehensive consideration of many complex factors. Automatic tracking and phenotyping of interacting animals could thus overcome the limitations of manual tracking methods. Here we report a broadly applicable system that automatically tracks the locations of multiple, uniquely identified animals, such as mice, within a semi-natural setting. The system combines video and radio frequency identified tracking data to obtain detailed behavioural profiles of both individuals and groups. We demonstrate the usefulness of these data in characterizing individual phenotypes, interactions between pairs and the collective social organization of groups.

  3. Use of the selective serotonin reuptake inhibitor citalopram in a possible animal analogue of obsessive-compulsive disorder.

    PubMed

    Stein, D J; Mendelsohn, I; Potocnik, F; Van Kradenberg, J; Wessels, C

    1998-01-01

    Canine acral lick dermatitis (ALD) has been suggested as an animal analogue of obsessive-compulsive disorder (OCD). A series of dogs with ALD or similar conditions were treated with citalopram, the most selective of the selective serotonin reuptake inhibitors. Six of nine (66.7%) dogs showed significant improvement. Given the apparent efficacy of citalopram in the treatment of OCD and related disorders, these data provide further evidence that ALD is a useful animal analogue of OCD.

  4. The minipig as an animal model to study Mycobacterium tuberculosis infection and natural transmission

    USDA-ARS?s Scientific Manuscript database

    Infants and children with tuberculosis (TB) account for more than 20% of cases in endemic countries. Current animal models study TB during adulthood but animal models for adolescent and infant TB are scarce. Here we propose that minipigs can be used as an animal model to study adult, adolescent and ...

  5. Unraveling the thread of nature's tapestry: the genetics of diversity and convergence in animal pigmentation.

    PubMed

    Kronforst, Marcus R; Barsh, Gregory S; Kopp, Artyom; Mallet, James; Monteiro, Antónia; Mullen, Sean P; Protas, Meredith; Rosenblum, Erica B; Schneider, Christopher J; Hoekstra, Hopi E

    2012-07-01

    Animals display incredibly diverse color patterns yet little is known about the underlying genetic basis of these phenotypes. However, emerging results are reshaping our view of how the process of phenotypic evolution occurs. Here, we outline recent research from three particularly active areas of investigation: melanin pigmentation in Drosophila, wing patterning in butterflies, and pigment variation in lizards. For each system, we highlight (i) the function and evolution of color variation, (ii) various approaches that have been used to explore the genetic basis of pigment variation, and (iii) conclusions regarding the genetic basis of convergent evolution which have emerged from comparative analyses. Results from these studies indicate that natural variation in pigmentation is a particularly powerful tool to examine the molecular basis of evolution, especially with regard to convergent or parallel evolution. Comparison of these systems also reveals that the molecular basis of convergent evolution is heterogeneous, sometimes involving conserved mechanisms and sometimes not. In the near future, additional work in other emerging systems will substantially expand the scope of available comparisons.

  6. Modelling nitrogen and carbon interactions in composting of animal manure in naturally aerated piles.

    PubMed

    Oudart, D; Robin, P; Paillat, J M; Paul, E

    2015-12-01

    Composting animal manure with natural aeration is a low-cost and low-energy process that can improve nitrogen recycling in millions of farms world-wide. Modelling can decrease the cost of choosing the best options for solid manure management in order to decrease the risk of loss of fertilizer value and ammonia emission. Semi-empirical models are suitable, considering the scarce data available in farm situations. Eleven static piles of pig or poultry manure were monitored to identify the main processes governing nitrogen transformations and losses. A new model was implemented to represent these processes in a pile considered as homogeneous. The model is based on four modules: biodegradation, nitrogen transformations and volatilization, thermal exchanges, and free air space evolution. When necessary, the parameters were calibrated with the data set. The results showed that microbial growth could reduce ammonia volatilization. Greatest nitrogen conservation is achieved when microbial growth was limited by nitrogen availability. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. The meaning of seasonal changes, nature, and animals for adolescent girls' wellbeing in northern Finland: A qualitative descriptive study.

    PubMed

    Wiens, Varpu; Kyngäs, Helvi; Pölkki, Tarja

    2016-01-01

    Wellbeing is complex, holistic, and subjectively perceived. Issues such as gender, age, and environment seem to affect it. Therefore, the aim of this qualitative study was to describe the meaning of seasonal changes, nature, and animals towards 13-16-year-old girls' wellbeing in Northern Finland. In the spring of 2014, through purposive sampling, a total of 19 girls participated in semi-structured interviews from various parts of Northern Finland. The data were analysed using content analysis. Afterwards, the analysis combining the category participatory involvement with environment was found, and this consisted of three main categories: adaptation to seasonal changes, restorative nature, and empowering interactivity with animals. Seasonal changes had an effect on girls' wellbeing; in the summertime, they felt happy and vivacious, active, and outgoing. Instead, during the winter months, girls' mood and activity seemed to be lower and they felt lazier and depressed. Nature brought mainly positive feelings to girls; being in nature was experienced as liberating and relaxing, and it offered opportunities to relax and have sensory perceptions. Interaction with animals was perceived as empowering. They were experienced as altruistic and comforting companions. Animals were important to girls, and they contributed to girls' lives through positive effects towards their mental and physical wellbeing. Based on the results of this study, we can recommend that being in nature and interacting with animals should be supported because they seem to have benefits towards adolescent girls' health and wellbeing. In order to facilitate the negative effects of winter, the school days should be arranged in such a way that it would be possible for girls to have outdoor activities during the daytime. The challenge for the future is perhaps the purposeful utilisation of nature's and the animals' positive effects towards their wellbeing.

  8. Plasmid DNA encoding targeted naturally processed peptides generates protective cytotoxic T lymphocyte responses in immunized animals.

    PubMed

    Hedley, M L; Strominger, J L; Urban, R G

    1998-02-10

    Genetic immunization has been widely applied in efforts to find novel and efficient mechanisms of stimulating the immune response. An effective attack against viral pathogens or tumors often requires activation of T cell-mediated immunity and the generation of cytotoxic T cells. Intramuscular immunization with plasmid DNA containing cDNAs that encode proteins results in expression and secretion of the foreign antigen by muscle cells. T cell activation occurs when peptide fragments of the exogenous protein are presented by major histocompatibility complex class I molecules on the surface of professional antigen-presenting cells. Identification of specific peptide epitopes from a protein antigen presented to T cells during an infectious process or tumor situation would provide all of the antigenic information needed to stimulate effective T cell-mediated immunity. Such peptides represent the naturally processed epitopes selected by the processing machinery of antigen presenting cells. Delivery of this information to the appropriate cells in vivo might be sufficient to stimulate T cell immunity and overcome the difficulties associated with overexpression of large protein antigens or those with potentially toxic side effects. This report describes the use of naturally processed T cell epitopes, administered in plasmid DNA vaccines, to stimulate cytotoxic T cell responses to two viral antigens effectively.

  9. Nature of men and higher animals' response to the lunar phases.

    NASA Astrophysics Data System (ADS)

    Troshichev, Oleg; Vladimir, Vorobeichikov; Viktor, Stepanov; Eduard, Gorshkov

    The Moon impact on the abnormal behavior of men and higher animals was marked during the entire mankind history, but the nature of this effect remained unclear. The popular hypothesis of the tidal influence of the Moon on the living organisms turned out to be incompatible with the contemporary biophysics concepts. In addition, the estimates of the lunar gravity influence on the men organism showed the negligible value of the possible effect. Vorobeichikov et al. [2006] were the first who suggested that the organisms' response to the lunar phases can be linked with the bacillus E.coli inhabiting in the bowels of the living organisms. E.coli belongs to family of enterobacteria, which are the important component of the human body microflora. Bacteria E.coli being sowed in the nutritious medium go in their development through four stages: adjusting, explosive reproducing, stationary, and dieing. The adjusting stage (or lagphase) is the most interesting for researchers, since duration of this phase L (the interval between the sowing time and the onset of the quick, exponential reproduction) is strongly influenced by the external conditions and can vary from standard 3 - 3.5 hours to some minutes. In our experiments the lag-phase L was determined for days of new moon and full moon, and for such exclusive events as the solar and lunar eclipses. The standard quantity of E.coli was sowed in the standard volume of the artificial nutritive. Lag-phase was detected every 1 minute near the key moment and every 15 minutes at other hours. It turned out that lag-phase is reduced to 1.5 hour for new moon, 1 hour for full moon, 0.5 hour for the lunar eclipse and falls to zero for the solar eclipse. In the latter case it took about 10 hours for the lag phase reduction before the eclipse and the lag-phase recovery after the eclipse. In case of a new moon the lag phase reduction lasted about half of hour. Thus, the close was the Moon to the line Sun-Earth, the shorter was lag phase and

  10. Copy number variants and selective sweeps in natural populations of the house mouse (Mus musculus domesticus)

    PubMed Central

    Bryk, Jarosław; Tautz, Diethard

    2014-01-01

    Copy–number variants (CNVs) may play an important role in early adaptations, potentially facilitating rapid divergence of populations. We describe an approach to study this question by investigating CNVs present in natural populations of mice in the early stages of divergence and their involvement in selective sweeps. We have analyzed individuals from two recently diverged natural populations of the house mouse (Mus musculus domesticus) from Germany and France using custom, high–density, comparative genome hybridization arrays (CGH) that covered almost 164 Mb and 2444 genes. One thousand eight hundred and sixty one of those genes we previously identified as differentially expressed between these populations, while the expression of the remaining genes was invariant. In total, we identified 1868 CNVs across all 10 samples, 200 bp to 600 kb in size and affecting 424 genic regions. Roughly two thirds of all CNVs found were deletions. We found no enrichment of CNVs among the differentially expressed genes between the populations compared to the invariant ones, nor any meaningful correlation between CNVs and gene expression changes. Among the CNV genes, we found cellular component gene ontology categories of the synapse overrepresented among all the 2444 genes tested. To investigate potential adaptive significance of the CNV regions, we selected six that showed large differences in frequency of CNVs between the two populations and analyzed variation in at least two microsatellites surrounding the loci in a sample of 46 unrelated animals from the same populations collected in field trappings. We identified two loci with large differences in microsatellite heterozygosity (Sfi1 and Glo1/Dnahc8 regions) and one locus with low variation across the populations (Cmah), thus suggesting that these genomic regions might have recently undergone selective sweeps. Interestingly, the Glo1 CNV has previously been implicated in anxiety–like behavior in mice, suggesting a

  11. Dynamics of extinction and the selection of nature reserves.

    PubMed Central

    Araújo, Miguel B; Williams, Paul H; Fuller, Robert J

    2002-01-01

    Familiar quantitative reserve-selection techniques are tailored to simple decision problems, where the representation of species is sought at minimum cost. However, conservationists have begun to ask whether representing species in reserve networks is sufficient to avoid local extinctions within selected areas. An attractive, but previously untested idea is to model current species' probabilities of occurrence as an estimate of local persistence in the near future. Using distribution data for passerine birds in Great Britain, we show that (i) species' probabilities of occurrence are negatively related to local probabilities of extinction, at least when a particular 20-year period is considered, and (ii) local extinctions can be reduced if areas are selected to maximize current species' probabilities of occurrence We suggest that more extinctions could be avoided if even a simple treatment of persistence were to be incorporated within reserve selection methods. PMID:12396495

  12. Natural selection on a major armor gene in threespine stickleback.

    PubMed

    Barrett, Rowan D H; Rogers, Sean M; Schluter, Dolph

    2008-10-10

    Experimental estimates of the effects of selection on genes determining adaptive traits add to our understanding of the mechanisms of evolution. We measured selection on genotypes of the Ectodysplasin locus, which underlie differences in lateral plates in threespine stickleback fish. A derived allele (low) causing reduced plate number has been fixed repeatedly after marine stickleback colonized freshwater from the sea, where the ancestral allele (complete) predominates. We transplanted marine sticklebacks carrying both alleles to freshwater ponds and tracked genotype frequencies over a generation. The low allele increased in frequency once lateral plates developed, most likely via a growth advantage. Opposing selection at the larval stage and changing dominance for fitness throughout life suggest either that the gene affects additional traits undergoing selection or that linked loci also are affecting fitness.

  13. Body Size Preference of Marine Animals in Relation to Extinction Selectivity

    NASA Astrophysics Data System (ADS)

    Sriram, A.; Idgunji, S.; Heim, N. A.; Payne, J.

    2014-12-01

    Our project encompasses an extremely specific aspect in relation to the five mass extinctions in geologic history. We asked ourselves whether larger or smaller body sizes would be better suited for surviving a mass extinction. To conduct research for our project, we used the body sizes of 17,172 marine animal genera as our primary data. These animals include echinoderms, arthropods, chordates, mollusks, and brachiopods. These creatures are perfect model organisms in terms of finding data on them because they have an excellent fossil record, and are well documented. We focused on the mean body size of these animals before and after each of the five mass extinctions (end-Ordovician, Late Devonian, end-Permian, end-Triassic, and end-Cretaceous). Our hypothesis was that the average biovolume of animals increased after each of the extinctions, with the mean size being greater after than it was before. Our size data is from the Ellis & Messina Catalogue of Ostracoda and the Treatise on Invertebrate Paleontology. We obtained stratigraphic range data The Treatise and Sepkoski (2002). In our analyses, we compared the mean size of the different animal genera before and after each extinction event. We further partitioned size change across mass extinction boundaries into three categories: the surviving genera, the extinct genera, and the newly originating genera that came about after the extinction. According to our analyses, the mean sizes did not change significantly from the genera living during the stages before the extinctions and after the extinctions. From our results, we can assume that there were not enough major increases in the overall volume of the organisms to warrant a definite conclusion that extinctions lead to larger body sizes. Further support for our findings came from the T-tests in our R code. Only the Cretaceous period showed true evidence for size changing because of the extinction; in this case, the mean size decreased. T-tests for the Cretaceous

  14. Phase-selective image reconstruction of the lungs in small animals using micro-CT

    NASA Astrophysics Data System (ADS)

    Johnston, S. M.; Perez, B. A.; Kirsch, D. G.; Badea, C. T.

    2010-04-01

    Gating in small animal imaging can compensate for artifacts due to physiological motion. This paper presents a strategy for sampling and image reconstruction in the rodent lung using micro-CT. The approach involves rapid sampling of freebreathing mice without any additional hardware to detect respiratory motion. The projection images are analyzed postacquisition to derive a respiratory signal, which is used to provide weighting factors for each projection that favor a selected phase of the respiration (e.g. end-inspiration or end-expiration) for the reconstruction. Since the sampling cycle and the respiratory cycle are uncorrelated, the sets of projections corresponding to any of the selected respiratory phases do not have a regular angular distribution. This drastically affects the image quality of reconstructions based on simple filtered backprojection. To address this problem, we use an iterative reconstruction algorithm that combines the Simultaneous Algebraic Reconstruction Technique with Total Variation minimization (SART-TV). At each SART-TV iteration, backprojection is performed with a set of weighting factors that favor the desired respiratory phase. To reduce reconstruction time, the algorithm is implemented on a graphics processing unit. The performance of the proposed approach was investigated in simulations and in vivo scans of mice with primary lung cancers imaged with our in-house developed dual tube/detector micro-CT system. We note that if the ECG signal is acquired during sampling, the same approach could be used for phase-selective cardiac imaging.

  15. A Selective Critique of Animal Experiments in Human-Orientated Biological Research.

    ERIC Educational Resources Information Center

    Webb, G. P.

    1990-01-01

    The advantages and justifications for using small animals in human-oriented research are reviewed. Some of the pitfalls of extrapolating animal-derived data to humans are discussed. Several specific problems with animal experimentation are highlighted. (CW)

  16. A Selective Critique of Animal Experiments in Human-Orientated Biological Research.

    ERIC Educational Resources Information Center

    Webb, G. P.

    1990-01-01

    The advantages and justifications for using small animals in human-oriented research are reviewed. Some of the pitfalls of extrapolating animal-derived data to humans are discussed. Several specific problems with animal experimentation are highlighted. (CW)

  17. Molecular bases for the selection of the chromophore of animal rhodopsins.

    PubMed

    Luk, Hoi Ling; Melaccio, Federico; Rinaldi, Silvia; Gozem, Samer; Olivucci, Massimo

    2015-12-15

    The functions of microbial and animal rhodopsins are triggered by the isomerization of their all-trans and 11-cis retinal chromophores, respectively. To lay the molecular basis driving the evolutionary transition from the all-trans to the 11-cis chromophore, multiconfigurational quantum chemistry is used to compare the isomerization mechanisms of the sensory rhodopsin from the cyanobacterium Anabaena PCC 7120 (ASR) and of the bovine rhodopsin (Rh). It is found that, despite their evolutionary distance, these eubacterial and vertebrate rhodopsins start to isomerize via distinct implementations of the same bicycle-pedal mechanism originally proposed by Warshel [Warshel A (1976) Nature 260:678-683]. However, by following the electronic structure changes of ASR (featuring the all-trans chromophore) during the isomerization, we find that ASR enters a region of degeneracy between the first and second excited states not found in Rh (featuring the 11-cis chromophore). We show that such degeneracy is modulated by the preorganized structure of the chromophore and by the position of the reactive double bond. It is argued that the optimization of the electronic properties of the chromophore, which affects the photoisomerization efficiency and the thermal isomerization barrier, provided a key factor for the emergence of the striking amino acid sequence divergence observed between the microbial and animal rhodopsins.

  18. Molecular bases for the selection of the chromophore of animal rhodopsins

    PubMed Central

    Luk, Hoi Ling; Melaccio, Federico; Rinaldi, Silvia; Gozem, Samer; Olivucci, Massimo

    2015-01-01

    The functions of microbial and animal rhodopsins are triggered by the isomerization of their all-trans and 11-cis retinal chromophores, respectively. To lay the molecular basis driving the evolutionary transition from the all-trans to the 11-cis chromophore, multiconfigurational quantum chemistry is used to compare the isomerization mechanisms of the sensory rhodopsin from the cyanobacterium Anabaena PCC 7120 (ASR) and of the bovine rhodopsin (Rh). It is found that, despite their evolutionary distance, these eubacterial and vertebrate rhodopsins start to isomerize via distinct implementations of the same bicycle-pedal mechanism originally proposed by Warshel [Warshel A (1976) Nature 260:678–683]. However, by following the electronic structure changes of ASR (featuring the all-trans chromophore) during the isomerization, we find that ASR enters a region of degeneracy between the first and second excited states not found in Rh (featuring the 11-cis chromophore). We show that such degeneracy is modulated by the preorganized structure of the chromophore and by the position of the reactive double bond. It is argued that the optimization of the electronic properties of the chromophore, which affects the photoisomerization efficiency and the thermal isomerization barrier, provided a key factor for the emergence of the striking amino acid sequence divergence observed between the microbial and animal rhodopsins. PMID:26607446

  19. Selected active naturals for atopic dermatitis: Atopic Dermatitis Part 1.

    PubMed

    Silverberg, Nanette B

    The desire for naturally derived agents is a growing trend for patients, physicians, and pharmaceutical companies. Studies indicate that complementary and alternative medicine is often used by patients and parents of children with atopic dermatitis, not necessarily with beneficial results. A half-dozen natural agents (ie, topical agents: coconut oil, colloidal oatmeal, sunflower oil, mustard oil, glycerin, and oral Chinese herbal therapy) are discussed because they have become popular for their expected activity in the therapy of atopic dermatitis. A critical review of the published literature on these agents is presented with specific focus on potential such side effects as hepatotoxicity with Chinese herbals. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Natural selection reduced diversity on human y chromosomes.

    PubMed

    Wilson Sayres, Melissa A; Lohmueller, Kirk E; Nielsen, Rasmus

    2014-01-01

    The human Y chromosome exhibits surprisingly low levels of genetic diversity. This could result from neutral processes if the effective population size of males is reduced relative to females due to a higher variance in the number of offspring from males than from females. Alternatively, selection acting on new mutations, and affecting linked neutral sites, could reduce variability on the Y chromosome. Here, using genome-wide analyses of X, Y, autosomal and mitochondrial DNA, in combination with extensive population genetic simulations, we show that low observed Y chromosome variability is not consistent with a purely neutral model. Instead, we show that models of purifying selection are consistent with observed Y diversity. Further, the number of sites estimated to be under purifying selection greatly exceeds the number of Y-linked coding sites, suggesting the importance of the highly repetitive ampliconic regions. While we show that purifying selection removing deleterious mutations can explain the low diversity on the Y chromosome, we cannot exclude the possibility that positive selection acting on beneficial mutations could have also reduced diversity in linked neutral regions, and may have contributed to lowering human Y chromosome diversity. Because the functional significance of the ampliconic regions is poorly understood, our findings should motivate future research in this area.

  1. Natural Selection Reduced Diversity on Human Y Chromosomes

    PubMed Central

    Wilson Sayres, Melissa A.; Lohmueller, Kirk E.; Nielsen, Rasmus

    2014-01-01

    The human Y chromosome exhibits surprisingly low levels of genetic diversity. This could result from neutral processes if the effective population size of males is reduced relative to females due to a higher variance in the number of offspring from males than from females. Alternatively, selection acting on new mutations, and affecting linked neutral sites, could reduce variability on the Y chromosome. Here, using genome-wide analyses of X, Y, autosomal and mitochondrial DNA, in combination with extensive population genetic simulations, we show that low observed Y chromosome variability is not consistent with a purely neutral model. Instead, we show that models of purifying selection are consistent with observed Y diversity. Further, the number of sites estimated to be under purifying selection greatly exceeds the number of Y-linked coding sites, suggesting the importance of the highly repetitive ampliconic regions. While we show that purifying selection removing deleterious mutations can explain the low diversity on the Y chromosome, we cannot exclude the possibility that positive selection acting on beneficial mutations could have also reduced diversity in linked neutral regions, and may have contributed to lowering human Y chromosome diversity. Because the functional significance of the ampliconic regions is poorly understood, our findings should motivate future research in this area. PMID:24415951

  2. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    PubMed Central

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural selection and also include discussions on sexual selection, molecular evolution, evolution of complex traits, and the evolution of behavior. The set of six topics gives students the opportunity to see how natural selection operates in a variety of contexts. Pre- and postinstruction testing showed students’ understanding of natural selection increased substantially after completing this series of learning activities. Testing throughout this unit showed steadily increasing student understanding, and surveys indicated students enjoyed the activities. PMID:24006396

  3. Six classroom exercises to teach natural selection to undergraduate biology students.

    PubMed

    Kalinowski, Steven T; Leonard, Mary J; Andrews, Tessa M; Litt, Andrea R

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural selection and also include discussions on sexual selection, molecular evolution, evolution of complex traits, and the evolution of behavior. The set of six topics gives students the opportunity to see how natural selection operates in a variety of contexts. Pre- and postinstruction testing showed students' understanding of natural selection increased substantially after completing this series of learning activities. Testing throughout this unit showed steadily increasing student understanding, and surveys indicated students enjoyed the activities.

  4. Comparative Analysis of Transcriptional Profiles of Adult Schistosoma japonicum from Different Laboratory Animals and the Natural Host, Water Buffalo

    PubMed Central

    Wu, Chuang; Hou, Nan; Chen, Qijun

    2015-01-01

    Background Schistosomiasis is one of the most widely distributed parasitic diseases in the world. Schistosoma japonicum, a zoonotic parasite with a wide range of mammalian hosts, is one of the major pathogens of this disease. Although numerous studies on schistosomiasis japonica have been performed using laboratory animal models, systematic comparative analysis of whole-genome expression profiles in parasites from different laboratory animals and nature mammalian hosts is lacking to date. Methodology/Principal Findings Adult schistosomes were obtained from laboratory animals BALB/c mice, C57BL/6 mice, New Zealand white rabbits and the natural host, water buffaloes. The gene expression profiles of schistosomes from these animals were obtained and compared by genome-wide oligonucleotide microarray analysis. The results revealed that the gene expression profiles of schistosomes from different laboratory animals and buffaloes were highly consistent (r>0.98) genome-wide. Meanwhile, a total of 450 genes were identified to be differentially expressed in schistosomes which can be clustered into six groups. Pathway analysis revealed that these genes were mainly involved in multiple signal transduction pathways, amino acid, energy, nucleotide and lipid metabolism. We also identified a group of 1,540 abundantly and stably expressed gene products in adult worms, including a panel of 179 Schistosoma- or Platyhelminthes-specific genes that may be essential for parasitism and may be regarded as novel potential anti-parasite intervention targets for future research. Conclusions/Significance This study provides a comprehensive database of gene expression profiles of schistosomes derived from different laboratory animals and water buffaloes. An expanded number of genes potentially affecting the development of schistosomes in different animals were identified. These findings lay the foundation for schistosomiasis research in different laboratory animals and natural hosts at the

  5. Comparative Analysis of Transcriptional Profiles of Adult Schistosoma japonicum from Different Laboratory Animals and the Natural Host, Water Buffalo.

    PubMed

    Liu, Shuai; Zhou, Xiaosu; Piao, Xianyu; Wu, Chuang; Hou, Nan; Chen, Qijun

    2015-08-01

    Schistosomiasis is one of the most widely distributed parasitic diseases in the world. Schistosoma japonicum, a zoonotic parasite with a wide range of mammalian hosts, is one of the major pathogens of this disease. Although numerous studies on schistosomiasis japonica have been performed using laboratory animal models, systematic comparative analysis of whole-genome expression profiles in parasites from different laboratory animals and nature mammalian hosts is lacking to date. Adult schistosomes were obtained from laboratory animals BALB/c mice, C57BL/6 mice, New Zealand white rabbits and the natural host, water buffaloes. The gene expression profiles of schistosomes from these animals were obtained and compared by genome-wide oligonucleotide microarray analysis. The results revealed that the gene expression profiles of schistosomes from different laboratory animals and buffaloes were highly consistent (r>0.98) genome-wide. Meanwhile, a total of 450 genes were identified to be differentially expressed in schistosomes which can be clustered into six groups. Pathway analysis revealed that these genes were mainly involved in multiple signal transduction pathways, amino acid, energy, nucleotide and lipid metabolism. We also identified a group of 1,540 abundantly and stably expressed gene products in adult worms, including a panel of 179 Schistosoma- or Platyhelminthes-specific genes that may be essential for parasitism and may be regarded as novel potential anti-parasite intervention targets for future research. This study provides a comprehensive database of gene expression profiles of schistosomes derived from different laboratory animals and water buffaloes. An expanded number of genes potentially affecting the development of schistosomes in different animals were identified. These findings lay the foundation for schistosomiasis research in different laboratory animals and natural hosts at the transcriptional level and provide a valuable resource for screening anti

  6. Selected References on Asbestos: Its Nature, Hazards, Detection, and Control.

    ERIC Educational Resources Information Center

    National Education Association, Washington, DC.

    This document provides teachers with sources of information about the nature, hazards, detection, and control of asbestos. Because many school buildings include asbestos-containing materials, teachers and other school personnel must be aware of the potential dangers to students and to themselves and take steps to have asbestos hazards contained or…

  7. The magnitude and selectivity of natural and multiple anthropogenic mortality causes in hunted brown bears.

    PubMed

    Bischof, Richard; Swenson, Jon E; Yoccoz, Nigel G; Mysterud, Atle; Gimenez, Olivier

    2009-05-01

    1. The population dynamic and evolutionary effects of harvesting are receiving growing attention among biologists. Cause-specific estimates of mortality are necessary to determine and compare the magnitude and selectivity of hunting and other types of mortalities. In addition to the logistic and financial constraints on longitudinal studies, they are complicated by the fact that nonhunting mortality in managed populations usually consists of a mix of natural and human-caused factors. 2. We used multistate capture-recapture (MCR) models to estimate cause-specific survival of brown bears (Ursus arctos) in two subpopulations in Sweden over a 23-year period. In our analysis, we distinguished between legal hunting and other sources of mortality, such as intraspecific predation, accidents, poaching, and damage control removals. We also tested whether a strong increase in harvest quotas after 1997 in one of the subpopulations affected vulnerability to legal hunting. 3. Although only a fraction of mortalities other than legal hunting could be considered natural, this group of causes showed a general pattern of demographic selectivity expected from natural mortality regimes in populations of long-lived species, namely greater vulnerability of young animals. On the other hand, demographic effects on hunting vulnerability were weak and inconsistent. Our findings support the assumption that hunting and other mortalities were additive. 4. As expected, an increase in hunting pressure coincided with a correspondingly large increase in vulnerability to hunting in the affected subpopulation. Because even unbiased harvest can lead to selective pressures on life-history traits, such as size at primiparity, increasing harvest quotas may not only affect population growth directly, but could also alter optimal life-history strategies in brown bears and other carnivores. 5. Legal hunting is the most conveniently assessed and the most easily managed cause of mortality in many wild

  8. Poised for survival: criticality, natural selection, and excitation-transcription coupling.

    PubMed

    Wallace, Ron

    2015-04-01

    Neurologically-complex species utilize two intricately coupled information-processing systems to adapt to their social and natural environments. Action potentials (APs) facilitate rapid responses to the nearly continuous fluctuations in the animal's surroundings. By contrast, genetic encodings comprise a molecular memory of ancient adaptive responses expressed as cognitive, emotional, or behavioral phenotypes. The linking of the two systems via intracellular Ca(2+) networks which address transcription factors - e.g., cAMP response element-binding protein (CREB) - is an appropriate focus for the biology of human behavior. Computational modeling utilizing Boolean networks (BNs) is a suitable qualitative method, requiring no kinetic information, for eliciting the systems' architectural properties. In particular, BNs can reveal critical intracellular regimes of possible evolutionary significance. As a platform for future research, we propose that those networks sufficiently robust to attenuate damaging intracellular noise and deleterious mutations, yet sufficiently close to chaos to permit or amplify adaptive noise and favorable mutations, would be favored by natural selection. Critical regimes of this type would be, literally, "poised for survival", and would stabilize and promote the survival of their correlated cultural phenotypes.

  9. Parallel shifts in ecology and natural selection in an island lizard

    PubMed Central

    Calsbeek, Ryan; Buermann, Wolfgang; Smith, Thomas B

    2009-01-01

    Background Natural selection is a potent evolutionary force that shapes phenotypic variation to match ecological conditions. However, we know little about the year-to-year consistency of selection, or how inter-annual variation in ecology shapes adaptive landscapes and ultimately adaptive radiations. Here we combine remote sensing data, field experiments, and a four-year study of natural selection to show that changes in vegetation structure associated with a severe drought altered both habitat use and natural selection in the brown anole, Anolis sagrei. Results In natural populations, lizards increased their use of vegetation in wet years and this was correlated with selection on limb length but not body size. By contrast, a die-back of vegetation caused by drought was followed by reduced arboreality, selection on body size, and relaxed selection on limb length. With the return of the rains and recovery of vegetation, selection reverted back to pre-drought pattern of selection acting on limb length but not body size. To test for the impact of vegetation loss on natural selection during the drought, we experimentally removed vegetation on a separate study island in a naturally wet year. The experiment revealed similar inter-annual changes in selection on body size but not limb length. Conclusion Our results illustrate the dynamic nature of ecology driving natural selection on Anolis morphology and emphasize the importance of inter-annual environmental variation in shaping adaptive variation. In addition, results illustrate the utility of using remote sensing data to examine ecology's role in driving natural selection. PMID:19126226

  10. Genetic signature of natural selection in first Americans

    PubMed Central

    G. Amorim, Carlos Eduardo; Nunes, Kelly; Meyer, Diogo; Comas, David; Bortolini, Maria Cátira; Salzano, Francisco Mauro; Hünemeier, Tábita

    2017-01-01

    When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases (FADS) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a protein-rich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments. PMID:28193867

  11. Parental assessment and treatment of food selectivity in natural settings.

    PubMed

    Najdowski, Adel C; Wallace, Michele D; Doney, Janice K; Ghezzi, Patrick M

    2003-01-01

    This study evaluated the effects of a parent-conducted functional analysis and treatment consisting of differential reinforcement of an alternative behavior, escape extinction, and demand fading on food selectivity in a young child with autism. Increases in food acceptance at home and in a restaurant were obtained.

  12. Evolutionary stasis in pollen morphogenesis due to natural selection.

    PubMed

    Matamoro-Vidal, Alexis; Prieu, Charlotte; Furness, Carol A; Albert, Béatrice; Gouyon, Pierre-Henri

    2016-01-01

    The contribution of developmental constraints and selective forces to the determination of evolutionary patterns is an important and unsolved question. We test whether the long-term evolutionary stasis observed for pollen morphogenesis (microsporogenesis) in eudicots is due to developmental constraints or to selection on a morphological trait shaped by microsporogenesis: the equatorial aperture pattern. Most eudicots have three equatorial apertures but several taxa have independently lost the equatorial pattern and have microsporogenesis decoupled from aperture pattern determination. If selection on the equatorial pattern limits variation, we expect to see increased variation in microsporogenesis in the nonequatorial clades. Variation of microsporogenesis was studied using phylogenetic comparative analyses in 83 species dispersed throughout eudicots including species with and without equatorial apertures. The species that have lost the equatorial pattern have highly variable microsporogenesis at the intra-individual and inter-specific levels regardless of their pollen morphology, whereas microsporogenesis remains stable in species with the equatorial pattern. The observed burst of variation upon loss of equatorial apertures shows that there are no strong developmental constraints precluding variation in microsporogenesis, and that the stasis is likely to be due principally to selective pressure acting on pollen morphogenesis because of its implication in the determination of the equatorial aperture pattern.

  13. Genetic signature of natural selection in first Americans.

    PubMed

    G Amorim, Carlos Eduardo; Nunes, Kelly; Meyer, Diogo; Comas, David; Bortolini, Maria Cátira; Salzano, Francisco Mauro; Hünemeier, Tábita

    2017-02-28

    When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases (FADS) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a protein-rich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments.

  14. Allozyme diversity of selected and natural loblolly pine populations

    Treesearch

    Ronald C. Schmidtling; E. Carroll; T. LaFarge

    1999-01-01

    Loblolly pine (Pinus taeda L.) megagametophytes and embryos were examined electrophoretically to compare the extent and distribution of genetic variability in allozymes of selected and wild populations. Range-wide collections of three different types were investigated in this study. These consisted of seed sampled from (1) a provenance test...

  15. Population differentiation in G matrix structure due to natural selection in Rana temporaria.

    PubMed

    Cano, José Manuel; Laurila, Anssi; Pało, Jukka; Merilä, Juha

    2004-09-01

    The additive genetic variance-covariance matrix (G) is a concept central to discussions about evolutionary change over time in a suite of traits. However, at the moment we do not know how fast G itself changes as a consequence of selection or how sensitive it is to environmental influences. We investigated possible evolutionary divergence and environmental influences on G using data from a factorial common-garden experiment where common frog (Rana temporaria) tadpoles from two divergent populations were exposed to three different environmental treatments. G-matrices were estimated using an animal model approach applied to data from a NCII breeding design. Matrix comparisons using both Flury and multivariate analysis of variance methods revealed significant differences in G matrices both between populations and between treatments within populations, the former being generally larger than the latter. Comparison of levels of population differentiation in trait means using Q(ST) indices with that observed in microsatellite markers (F(ST)) revealed that the former values generally exceeded the neutral expectation set by F(ST). Hence, the results suggest that intraspecific divergence in G matrix structure has occurred mainly due to natural selection.

  16. Relative contribution of dispersal and natural selection to the maintenance of a hybrid zone in Littorina.

    PubMed

    Cruz, Raquel; Vilas, Carlos; Mosquera, Javier; García, Carlos

    2004-12-01

    Habitat preference behavior may play an important role in nonallopatric speciation. However, most examples of habitat preference contributing to differentiation within natural populations correspond to parasites or herbivores living in the discrete environments constituted by their animal or plant hosts. In the present study we investigated migration guided by habitat preference in the intertidal snail Littorina saxatilis in a hybrid zone associated with an ecotone across the shore, which is therefore a continuously varying environment. First, we found evidence for this behavior in one of the two locations studied. Second, we made reciprocal transplants to suppress the phenotypic gradient observed across the hybrid zone and measured the relative contributions of selection and migration to its regeneration. Selection played an important role at the two locations studied, but migration was only important at one, where it accounted for between a third and a half of the regenerated gradient. This overall minor effect of migration was relevant for theoretical models dealing with nonallopatric speciation, because it suggested that variation for habitat preference did not have an important role in the initiation of the differentiation process. The preference behavior observed in the hybrid zone would have evolved secondarily, as a consequence of habitat-dependent fitness differences between phenotypes.

  17. The meaning of seasonal changes, nature, and animals for adolescent girls’ wellbeing in northern Finland: A qualitative descriptive study

    PubMed Central

    Wiens, Varpu; Kyngäs, Helvi; Pölkki, Tarja

    2016-01-01

    Wellbeing is complex, holistic, and subjectively perceived. Issues such as gender, age, and environment seem to affect it. Therefore, the aim of this qualitative study was to describe the meaning of seasonal changes, nature, and animals towards 13–16-year-old girls’ wellbeing in Northern Finland. In the spring of 2014, through purposive sampling, a total of 19 girls participated in semi-structured interviews from various parts of Northern Finland. The data were analysed using content analysis. Afterwards, the analysis combining the category participatory involvement with environment was found, and this consisted of three main categories: adaptation to seasonal changes, restorative nature, and empowering interactivity with animals. Seasonal changes had an effect on girls’ wellbeing; in the summertime, they felt happy and vivacious, active, and outgoing. Instead, during the winter months, girls’ mood and activity seemed to be lower and they felt lazier and depressed. Nature brought mainly positive feelings to girls; being in nature was experienced as liberating and relaxing, and it offered opportunities to relax and have sensory perceptions. Interaction with animals was perceived as empowering. They were experienced as altruistic and comforting companions. Animals were important to girls, and they contributed to girls’ lives through positive effects towards their mental and physical wellbeing. Based on the results of this study, we can recommend that being in nature and interacting with animals should be supported because they seem to have benefits towards adolescent girls’ health and wellbeing. In order to facilitate the negative effects of winter, the school days should be arranged in such a way that it would be possible for girls to have outdoor activities during the daytime. The challenge for the future is perhaps the purposeful utilisation of nature's and the animals’ positive effects towards their wellbeing. PMID:26905401

  18. Aberrant Time to Most Recent Common Ancestor as a Signature of Natural Selection.

    PubMed

    Hunter-Zinck, Haley; Clark, Andrew G

    2015-10-01

    Natural selection inference methods often target one mode of selection of a particular age and strength. However, detecting multiple modes simultaneously, or with atypical representations, would be advantageous for understanding a population's evolutionary history. We have developed an anomaly detection algorithm using distributions of pairwise time to most recent common ancestor (TMRCA) to simultaneously detect multiple modes of natural selection in whole-genome sequences. As natural selection distorts local genealogies in distinct ways, the method uses pairwise TMRCA distributions, which approximate genealogies at a nonrecombining locus, to detect distortions without targeting a specific mode of selection. We evaluate the performance of our method, TSel, for both positive and balancing selection over different time-scales and selection strengths and compare TSel's performance with that of other methods. We then apply TSel to the Complete Genomics diversity panel, a set of human whole-genome sequences, and recover loci previously inferred to be under positive or balancing selection.

  19. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    ERIC Educational Resources Information Center

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural…

  20. Evolution of Students' Ideas about Natural Selection through a Constructivist Framework

    ERIC Educational Resources Information Center

    Baumgartner, Erin; Duncan, Kanesa

    2009-01-01

    Educating students about the process of evolution through natural selection is vitally important because not only is it the unifying theory of biological science, it is also widely regarded as difficult for students to fully comprehend. Anderson and colleagues (2002) describe alternative ideas and misconceptions about natural selection as highly…

  1. Six Classroom Exercises to Teach Natural Selection to Undergraduate Biology Students

    ERIC Educational Resources Information Center

    Kalinowski, Steven T.; Leonard, Mary J.; Andrews, Tessa M.; Litt, Andrea R.

    2013-01-01

    Students in introductory biology courses frequently have misconceptions regarding natural selection. In this paper, we describe six activities that biology instructors can use to teach undergraduate students in introductory biology courses how natural selection causes evolution. These activities begin with a lesson introducing students to natural…

  2. Evolution of Students' Ideas about Natural Selection through a Constructivist Framework

    ERIC Educational Resources Information Center

    Baumgartner, Erin; Duncan, Kanesa

    2009-01-01

    Educating students about the process of evolution through natural selection is vitally important because not only is it the unifying theory of biological science, it is also widely regarded as difficult for students to fully comprehend. Anderson and colleagues (2002) describe alternative ideas and misconceptions about natural selection as highly…

  3. Natural selection can favour ‘irrational’ behaviour

    PubMed Central

    McNamara, J. M.; Trimmer, P. C.; Houston, A. I.

    2014-01-01

    Understanding decisions is the fundamental aim of the behavioural sciences. The theory of rational choice is based on axiomatic principles such as transitivity and independence of irrelevant alternatives (IIA). Empirical studies have demonstrated that the behaviour of humans and other animals often seems irrational; there can be a lack of transitivity in choice and seemingly irrelevant alternatives can alter decisions. These violations of transitivity and IIA undermine rational choice theory. However, we show that an individual that is maximizing its rate of food gain can exhibit failure of transitivity and IIA. We show that such violations can be caused because a current option may disappear in the near future or a better option may reappear soon. Current food options can be indicative of food availability in the near future, and this key feature can result in apparently irrational behaviour. PMID:24429682

  4. Measuring Animal Movements in a Natural Ecosystem: A Mark-Recapture Investigation Using Stream-Dwelling Snails

    ERIC Educational Resources Information Center

    Stewart, Timothy W.

    2007-01-01

    In this investigation, students measure and describe movements of animals in a natural ecosystem. Students mark stream-dwelling snails with nail polish, then search for these snails 1-7 days later. Distances and directions moved by recaptured snails are recorded. Simple statistical techniques are used to answer specific research questions and…

  5. Animal Sociology and a Natural Economy of the Body Politic, Part 1: A Political Physiology of Dominance

    ERIC Educational Resources Information Center

    Haraway, Donna

    1978-01-01

    Justification of male dominance in society has been based frequently on findings in biobehavioral sciences, especially the science of animal groups. The natural and social sciences must be remade and forged in a dialectical understanding of social relations that is not based on domination. (Author/KR)

  6. Measuring Animal Movements in a Natural Ecosystem: A Mark-Recapture Investigation Using Stream-Dwelling Snails

    ERIC Educational Resources Information Center

    Stewart, Timothy W.

    2007-01-01

    In this investigation, students measure and describe movements of animals in a natural ecosystem. Students mark stream-dwelling snails with nail polish, then search for these snails 1-7 days later. Distances and directions moved by recaptured snails are recorded. Simple statistical techniques are used to answer specific research questions and…

  7. Interaction between natural and sexual selection during the evolution of mate recognition.

    PubMed

    Blows, Mark W

    2002-06-07

    The interaction between natural and sexual selection is central to many theories of how mate choice and reproductive isolation evolve, but their joint effect on the evolution of mate recognition has not, to my knowledge, been investigated in an evolutionary experiment. Natural and sexual selection were manipulated in interspecific hybrid populations of Drosophila to determine their effects on the evolution of a mate recognition system comprised of cuticular hydrocarbons (CHCs). The effect of natural selection in isolation indicated that CHCs were costly for males and females to produce. The effect of sexual selection in isolation indicated that females preferred males with a particular CHC composition. However, the interaction between natural and sexual selection had a greater effect on the evolution of the mate recognition system than either process in isolation. When natural and sexual selection were permitted to operate in combination, male CHCs became exaggerated to a greater extent than in the presence of sexual selection alone, and female CHCs evolved against the direction of natural selection. This experiment demonstrated that the interaction between natural and sexual selection is critical in determining the direction and magnitude of the evolutionary response of the mate recognition system.

  8. Flowering phenology: An example of relaxation of natural selection?

    PubMed

    Ollerton, J; Lack, A J

    1992-08-01

    Flowering phenology has normally been viewed as fundamental to a plant species' reproductive ecology. Researchers in the field have emphasized the adaptive importance of flowering at a particular time relative to other individuals in the population, or other species in the community. An alternative view, however, is that flowering phenology is a trait that may not be under strong selection, and this may have allowed some variation to appear in populations by chance. Copyright © 1992. Published by Elsevier Ltd.

  9. Development and Validation of the Conceptual Assessment of Natural Selection (CANS)

    PubMed Central

    Kalinowski, Steven T.; Leonard, Mary J.; Taper, Mark L.

    2016-01-01

    We developed and validated the Conceptual Assessment of Natural Selection (CANS), a multiple-choice test designed to assess how well college students understand the central principles of natural selection. The expert panel that reviewed the CANS concluded its questions were relevant to natural selection and generally did a good job sampling the specific concepts they were intended to assess. Student interviews confirmed questions on the CANS provided accurate reflections of how students think about natural selection. And, finally, statistical analysis of student responses using item response theory showed that the CANS did a very good job of estimating how well students understood natural selection. The empirical reliability of the CANS was substantially higher than the Force Concept Inventory, a highly regarded test in physics that has a similar purpose. PMID:27856552

  10. Just like the rest of evolution in Mother Nature, the evolution of cancers may be driven by natural selection, and not by haphazard mutations

    PubMed Central

    Zhang, Ju; Lou, Xiaomin; Zellmer, Lucas; Liu, Siqi; Xu, Ningzhi; Liao, D. Joshua

    2014-01-01

    Sporadic carcinogenesis starts from immortalization of a differentiated somatic cell or an organ-specific stem cell. The immortalized cell incepts a new or quasinew organism that lives like a parasite in the patient and usually proceeds to progressive simplification, constantly engendering intermediate organisms that are simpler than normal cells. Like organismal evolution in Mother Nature, this cellular simplification is a process of Darwinian selection of those mutations with growth- or survival-advantages, from numerous ones that occur randomly and stochastically. Therefore, functional gain of growth- or survival-sustaining oncogenes and functional loss of differentiation-sustaining tumor suppressor genes, which are hallmarks of cancer cells and contribute to phenotypes of greater malignancy, are not drivers of carcinogenesis but are results from natural selection of advantageous mutations. Besides this mutation-load dependent survival mechanism that is evolutionarily low and of an asexual nature, cancer cells may also use cell fusion for survival, which is an evolutionarily-higher mechanism and is of a sexual nature. Assigning oncogenes or tumor suppressor genes or their mutants as drivers to induce cancer in animals may somewhat coerce them to create man-made oncogenic pathways that may not really be a course of sporadic cancer formations in the human. PMID:25594068

  11. Animals Alive! An Ecological Guide to Animal Activities.

    ERIC Educational Resources Information Center

    Holley, Dennis

    Animals Alive! is designed to help teachers develop an inquiry-oriented program for studying the animal kingdom in which, whenever possible, live animals are collected locally, studied, observed, and then released completely unharmed back into their natural habitats. By careful selection and modification of the chapter questions, activities, and…

  12. Animals Alive! An Ecological Guide to Animal Activities.

    ERIC Educational Resources Information Center

    Holley, Dennis

    Animals Alive! is designed to help teachers develop an inquiry-oriented program for studying the animal kingdom in which, whenever possible, live animals are collected locally, studied, observed, and then released completely unharmed back into their natural habitats. By careful selection and modification of the chapter questions, activities, and…

  13. Tardigrades living in extreme environments have naturally selected prerequisites useful to space conquer

    NASA Astrophysics Data System (ADS)

    Guidetti, Roberto; Tiziana, Altiero; Cesari, Michele; Rizzo, Angela Maria; Bertolani, Roberto; Galletta, Giuseppe; Dalessandro, Maurizio; Rebecchi, Lorena

    Extreme habitats are highly selective and can host only living organisms possessing specific adaptations to stressors. Among extreme habitats, space environment has particular charac-teristics of radiations, vacuum, microgravity and temperature, which induce rapid changes in living systems. Consequently, the response of multicellular complex organisms, able to colo-nize extreme environments, to space stresses can give very useful information on the ability to withstand a single stress or stress combinations. This knowledge on changes in living systems in space, with their similarity to the ageing processes, offers the opportunity to improve human life both on Earth and in space. Even though experimentation in space has often been carried out using unicellular organisms, multicellular organisms are very relevant in order to develop the appropriate countermeasures to avoid the risks imposed by environmental space in humans. The little attention received by multicellular organisms is probably due, other than to difficul-ties in the manipulation of biological materials in space, to the presence of only few organisms with the potential to tolerate environmental space stresses. Among them, tardigrades are small invertebrates representing an attractive animal model to study adaptive strategies for surviving extreme environments, including space environment. Tardigrades are little known microscopic aquatic animals (250-800 m in body length) distributed in different environments (from the deep sea to high mountains and deserts all over the world), and frequently inhabiting very unstable and unpredictable habitats (e.g. interstices of mosses, lichens, leaf litter, freshwater ponds, cryoconite holes). Their ability to live in the extreme environments is related to a wide variety of their life histories and adaptive strategies. A widespread and crucial strategy is cryptobiosis, a form of quiescence. It includes strategies such as anhydrobiosis and cryobiosis, characterized by

  14. Predator-mediated natural selection on the wings of the damselfly Calopteryx splendens: differences in selection among trait types.

    PubMed

    Kuchta, Shawn R; Svensson, Erik I

    2014-07-01

    Traits that increase mating success in males may come at a cost, such as an increased risk of predation. However, predator-mediated selection is challenging to document in natural populations, hampering our understanding of the trade-offs between sexual selection and predation. Here we report on a study of predator-mediated natural selection on wing traits in the damselfly Calopteryx splendens, the males of which possess conspicuous wing patches. Wagtails (genus Motacilla) are important avian predators of C. splendens, capturing them in flight and removing the wings prior to consumption. Using geometric morphometric techniques, we quantified the strength and mode of selection on wing traits by comparing wings from depredated individuals with the standing variation present in the population. Our results reveal that predator-mediated selection is stronger on secondary sexual characters than on size and shape, suggesting that traits related to flight performance are closer to their adaptive peaks. This could be a consequence of the long-term evolutionary association with avian predators, whereas stronger selection on conspicuous secondary sexual traits may reflect trade-offs between sexual and natural selection. Finally, even though C. splendens possesses nearly identical fore- and hindwings, we found evidence for divergent selection between them.

  15. Pollinators exert natural selection on flower size and floral display in Penstemon digitalis.

    PubMed

    Parachnowitsch, Amy L; Kessler, André

    2010-10-01

    • A major gap in our understanding of floral evolution, especially micro-evolutionary processes, is the role of pollinators in generating patterns of natural selection on floral traits. Here we explicitly tested the role of pollinators in selecting floral traits in a herbaceous perennial, Penstemon digitalis. • We manipulated the effect of pollinators on fitness through hand pollinations and compared phenotypic selection in open- and hand-pollinated plants. • Despite the lack of pollen limitation in our population, pollinators mediated selection on floral size and floral display. Hand pollinations removed directional selection for larger flowers and stabilizing selection on flower number, suggesting that pollinators were the agents of selection on both of these traits. • We reviewed studies that measured natural selection on floral traits by biotic agents and generally found stronger signatures of selection imposed by pollinators than by herbivores and co-flowering plant species. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

  16. Selective looking at natural scenes: Hedonic content and gender.

    PubMed

    Bradley, Margaret M; Costa, Vincent D; Lang, Peter J

    2015-10-01

    Choice viewing behavior when looking at affective scenes was assessed to examine differences due to hedonic content and gender by monitoring eye movements in a selective looking paradigm. On each trial, participants viewed a pair of pictures that included a neutral picture together with an affective scene depicting either contamination, mutilation, threat, food, nude males, or nude females. The duration of time that gaze was directed to each picture in the pair was determined from eye fixations. Results indicated that viewing choices varied with both hedonic content and gender. Initially, gaze duration for both men and women was heightened when viewing all affective contents, but was subsequently followed by significant avoidance of scenes depicting contamination or nude males. Gender differences were most pronounced when viewing pictures of nude females, with men continuing to devote longer gaze time to pictures of nude females throughout viewing, whereas women avoided scenes of nude people, whether male or female, later in the viewing interval. For women, reported disgust of sexual activity was also inversely related to gaze duration for nude scenes. Taken together, selective looking as indexed by eye movements reveals differential perceptual intake as a function of specific content, gender, and individual differences. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Selective looking at natural scenes: Hedonic content and gender☆

    PubMed Central

    Bradley, Margaret M.; Costa, Vincent D.; Lang, Peter J.

    2015-01-01

    Choice viewing behavior when looking at affective scenes was assessed to examine differences due to hedonic content and gender by monitoring eye movements in a selective looking paradigm. On each trial, participants viewed a pair of pictures that included a neutral picture together with an affective scene depicting either contamination, mutilation, threat, food, nude males, or nude females. The duration of time that gaze was directed to each picture in the pair was determined from eye fixations. Results indicated that viewing choices varied with both hedonic content and gender. Initially, gaze duration for both men and women was heightened when viewing all affective contents, but was subsequently followed by significant avoidance of scenes depicting contamination or nude males. Gender differences were most pronounced when viewing pictures of nude females, with men continuing to devote longer gaze time to pictures of nude females throughout viewing, whereas women avoided scenes of nude people, whether male or female, later in the viewing interval. For women, reported disgust of sexual activity was also inversely related to gaze duration for nude scenes. Taken together, selective looking as indexed by eye movements reveals differential perceptual intake as a function of specific content, gender, and individual differences. PMID:26156939

  18. Coevolution of cooperation and network structure under natural selection

    NASA Astrophysics Data System (ADS)

    Yang, D.-P.; Lin, H.; Shuai, J. W.

    2011-02-01

    A coevolution model by coupling mortality and fertility selection is introduced to investigate the evolution of cooperation and network structure in the prisoner's dilemma game. The cooperation level goes through a continuous phase transition vs. defection temptation b for low mortality selection intensity β and through a discontinuous one for infinite β. The cooperation level is enhanced most at β≈1 for any b. The local and global properties of the network structure, such as cluster and cooperating k-core, are investigated for the understanding of cooperation evolution. Cooperation is promoted by forming a tight cooperating k-core at moderate β, but too large β will destroy the cooperating k-core rapidly resulting in a rapid drop of the cooperation level. Importantly, the infinite β changes the normalized sucker's payoff S from 0 to 1-b and its dynamics of the cooperation level undergoes a very slow power-law decay, which leads the evolution into the regime of neutral evolution.

  19. Natural and sexual selection act on different axes of variation in avian plumage color

    PubMed Central

    Dunn, Peter O.; Armenta, Jessica K.; Whittingham, Linda A.

    2015-01-01

    The bright colors of birds are often attributed to sexual selection on males, but in many species both sexes are colorful and it has been long debated whether sexual selection can also explain this variation. We show that most evolutionary transitions in color have been toward similar plumage in both sexes, and the color of both sexes (for example, bright or dull) was associated with indices of natural selection (for example, habitat type), whereas sexual differences in color were primarily associated with indices of sexual selection on males (for example, polygyny and large testes size). Debate about the evolution of bird coloration can be resolved by recognizing that both natural and sexual selection have been influential, but they have generally acted on two different axes: sexual selection on an axis of sexual differences and natural selection on both sexes for the type of color (for example, bright or dull). PMID:26601146

  20. Affective Neuronal Selection: The Nature of the Primordial Emotion Systems

    PubMed Central

    Toronchuk, Judith A.; Ellis, George F. R.

    2013-01-01

    Based on studies in affective neuroscience and evolutionary psychiatry, a tentative new proposal is made here as to the nature and identification of primordial emotional systems. Our model stresses phylogenetic origins of emotional systems, which we believe is necessary for a full understanding of the functions of emotions and additionally suggests that emotional organizing systems play a role in sculpting the brain during ontogeny. Nascent emotional systems thus affect cognitive development. A second proposal concerns two additions to the affective systems identified by Panksepp. We suggest there is substantial evidence for a primary emotional organizing program dealing with power, rank, dominance, and subordination which instantiates competitive and territorial behavior and is an evolutionary contributor to self-esteem in humans. A program underlying disgust reactions which originally functioned in ancient vertebrates to protect against infection and toxins is also suggested. PMID:23316177

  1. Affective neuronal selection: the nature of the primordial emotion systems.

    PubMed

    Toronchuk, Judith A; Ellis, George F R

    2012-01-01

    Based on studies in affective neuroscience and evolutionary psychiatry, a tentative new proposal is made here as to the nature and identification of primordial emotional systems. Our model stresses phylogenetic origins of emotional systems, which we believe is necessary for a full understanding of the functions of emotions and additionally suggests that emotional organizing systems play a role in sculpting the brain during ontogeny. Nascent emotional systems thus affect cognitive development. A second proposal concerns two additions to the affective systems identified by Panksepp. We suggest there is substantial evidence for a primary emotional organizing program dealing with power, rank, dominance, and subordination which instantiates competitive and territorial behavior and is an evolutionary contributor to self-esteem in humans. A program underlying disgust reactions which originally functioned in ancient vertebrates to protect against infection and toxins is also suggested.

  2. Natural selection of the critical period for language acquisition.

    PubMed Central

    Komarova, N. L.; Nowak, M. A.

    2001-01-01

    The language acquisition period in humans lasts about 13 years. After puberty it becomes increasingly difficult to learn a language. We explain this phenomenon by using an evolutionary framework. We present a dynamical system describing competition between language acquisition devices, which differ in the length of the learning period. There are two selective forces that play a role in determining the critical learning period: (i) having a longer learning period increases the accuracy of language acquisition; (ii) learning is associated with certain costs that affect fitness. As a result, there exists a limited learning period which is evolutionarily stable. This result is obtained analytically by means of a Nash equilibrium analysis of language acquisition devices. Interestingly, the evolutionarily stable learning period does not maximize the average fitness of the population. PMID:11375108

  3. The Nature of Irac-selected Extremely Red Objects

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Huang, J.; Gu, Q.

    2010-05-01

    Using deep U-8um photometry from GEMs, MUSYC and SIMPLE surveys, we investigate properties of a large sample of IRAC-selected extremely red galaxies(IEROs). The sample comprises 304 brightest IEROs distributed over the GEMS field with a total area of 800 arcmin2, which satisfy ([3.6]+[4.5]/2)<21.2 and z-[3.6] > 3.25). Combined with the deepest Chandra and Spitzer surveys in this field, we are able to determine relative contributions of AGNs, (dusty) star-forming galaxies and passively evolving systems to the RED population; 51 sources are detected in at least one of three X-ray bands, leaving 253 non-Xray sources with 179 detected in 24um( 20uJy, 3sigma), indicating that at most 25% of these IEROs are passively evolving.We derive and examine photometric redshift using different methods; their redshift range from 1 to 2.6 with the median value at 1.5. Stellar masses of non-Xray sources are also derived with SED fitting methods, achieving a median value of 0.4*1011 Msun for a chrabrier initial mass function. The properties of best-fitting BC03 models are consistent with templates used for estimating redshifts, which have on average E(B-V) of 0.5 for 24um-deteced galaxies. The corresponding star-formation rates of these star-forming galaxies through SED fitting are within 40-100 Msun yr-1, consistent with that derived from their 24μm flux, which show a median total infrared luminosity 1*1011Lsun. We argue that such selected IEROs may represent a transient population from ULIRGs to LIRGs, and are likely descents of SMGs or DOGs.

  4. Geographical structure and differential natural selection among North European populations.

    PubMed

    McEvoy, Brian P; Montgomery, Grant W; McRae, Allan F; Ripatti, Samuli; Perola, Markus; Spector, Tim D; Cherkas, Lynn; Ahmadi, Kourosh R; Boomsma, Dorret; Willemsen, Gonneke; Hottenga, Jouke J; Pedersen, Nancy L; Magnusson, Patrik K E; Kyvik, Kirsten Ohm; Christensen, Kaare; Kaprio, Jaakko; Heikkilä, Kauko; Palotie, Aarno; Widen, Elisabeth; Muilu, Juha; Syvänen, Ann-Christine; Liljedahl, Ulrika; Hardiman, Orla; Cronin, Simon; Peltonen, Leena; Martin, Nicholas G; Visscher, Peter M

    2009-05-01

    Population structure can provide novel insight into the human past, and recognizing and correcting for such stratification is a practical concern in gene mapping by many association methodologies. We investigate these patterns, primarily through principal component (PC) analysis of whole genome SNP polymorphism, in 2099 individuals from populations of Northern European origin (Ireland, United Kingdom, Netherlands, Denmark, Sweden, Finland, Australia, and HapMap European-American). The major trends (PC1 and PC2) demonstrate an ability to detect geographic substructure, even over a small area like the British Isles, and this information can then be applied to finely dissect the ancestry of the European-Australian and European-American samples. They simultaneously point to the importance of considering population stratification in what might be considered a small homogeneous region. There is evidence from F(ST)-based analysis of genic and nongenic SNPs that differential positive selection has operated across these populations despite their short divergence time and relatively similar geographic and environmental range. The pressure appears to have been focused on genes involved in immunity, perhaps reflecting response to infectious disease epidemic. Such an event may explain a striking selective sweep centered on the rs2508049-G allele, close to the HLA-G gene on chromosome 6. Evidence of the sweep extends over a 8-Mb/3.5-cM region. Overall, the results illustrate the power of dense genotype and sample data to explore regional population variation, the events that have crafted it, and their implications in both explaining disease prevalence and mapping these genes by association.

  5. The Birds and the Beasts Were There: Animals in Their Natural Habitats. (A Multimedia Bibliography Revised). Library Media for Grades 4-6, Library Media for Grades 9-11.

    ERIC Educational Resources Information Center

    Sullivan, Marjorie; Strader, Helen

    This compilation lists 247 print and non-print materials dealing with animal life, nature, and ecology and is designed to assist teachers and school librarians in selecting media suitable for pupils in grades 4 through 6 and 9 through 12. A few of the materials date back to 1951, but the majority are of more recent issue. The collection for…

  6. Revisiting the syntactic abilities of non-human animals: natural vocalizations and artificial grammar learning

    PubMed Central

    ten Cate, Carel; Okanoya, Kazuo

    2012-01-01

    The domain of syntax is seen as the core of the language faculty and as the most critical difference between animal vocalizations and language. We review evidence from spontaneously produced vocalizations as well as from perceptual experiments using artificial grammars to analyse animal syntactic abilities, i.e. abilities to produce and perceive patterns following abstract rules. Animal vocalizations consist of vocal units (elements) that are combined in a species-specific way to create higher order strings that in turn can be produced in different patterns. While these patterns differ between species, they have in common that they are no more complex than a probabilistic finite-state grammar. Experiments on the perception of artificial grammars confirm that animals can generalize and categorize vocal strings based on phonetic features. They also demonstrate that animals can learn about the co-occurrence of elements or learn simple ‘rules’ like attending to reduplications of units. However, these experiments do not provide strong evidence for an ability to detect abstract rules or rules beyond finite-state grammars. Nevertheless, considering the rather limited number of experiments and the difficulty to design experiments that unequivocally demonstrate more complex rule learning, the question of what animals are able to do remains open. PMID:22688634

  7. Revisiting the syntactic abilities of non-human animals: natural vocalizations and artificial grammar learning.

    PubMed

    ten Cate, Carel; Okanoya, Kazuo

    2012-07-19

    The domain of syntax is seen as the core of the language faculty and as the most critical difference between animal vocalizations and language. We review evidence from spontaneously produced vocalizations as well as from perceptual experiments using artificial grammars to analyse animal syntactic abilities, i.e. abilities to produce and perceive patterns following abstract rules. Animal vocalizations consist of vocal units (elements) that are combined in a species-specific way to create higher order strings that in turn can be produced in different patterns. While these patterns differ between species, they have in common that they are no more complex than a probabilistic finite-state grammar. Experiments on the perception of artificial grammars confirm that animals can generalize and categorize vocal strings based on phonetic features. They also demonstrate that animals can learn about the co-occurrence of elements or learn simple 'rules' like attending to reduplications of units. However, these experiments do not provide strong evidence for an ability to detect abstract rules or rules beyond finite-state grammars. Nevertheless, considering the rather limited number of experiments and the difficulty to design experiments that unequivocally demonstrate more complex rule learning, the question of what animals are able to do remains open.

  8. Opportunity for natural selection among five population groups of Manipur, North East India.

    PubMed

    Asghar, M; Meitei, S Y; Luxmi, Y; Achoubi, N; Meitei, K S; Murry, B; Sachdeva, M P; Saraswathy, K N

    2014-01-01

    Opportunity for natural selection among five population groups of Manipur in comparison with other North East Indian population has been studied. Crow's index as well as Johnston and Kensinger's index for natural selection were calculated based on differential fertility and mortality. The mortality component was found to be lower compared to fertility component in all the populations which may attribute to comparatively improved and easily accessible health care facilities. However, different selection pressures, artificial and natural, seem to be influencing the selection intensity through induced abortion and spontaneous abortion among the two non-tribal migrant groups: Bamon and Muslims, respectively. This study highlights the probable interaction of artificial and natural selection in determining the evolutionary fate of any population group.

  9. Selective toxicity of Catechin-a natural flavonoid towards bacteria.

    PubMed

    Fathima, Aafreen; Rao, Jonnalagadda Raghava

    2016-07-01

    Catechin is a plant polyphenol composed of epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) as diastereoisomers. Among the various classes of flavonoids, catechin was found to be the most powerful free radical scavenger, scavenging the reactive oxygen species (ROS) generated due to oxidative damage with antibacterial and anti-inflammatory activity. The toxicity of catechin towards bacteria was studied using gram-positive bacteria (B. subtilis) and gram-negative bacteria (E. coli) as model organisms and was found to be more toxic towards gram-positive bacteria. From the results, catechin was found to be beneficial as well as toxic (inhibitory) to the bacteria at a selective concentration behaving as double-edged swords with an IC50 value of 9 ppm for both the bacteria. The inhibitory mechanism of catechin was by oxidative damage through membrane permeabilization which was confirmed by the formation and treatment of bacterial liposomes. SEM images of the control and treated bacteria reveals membrane damage with morphological changes.

  10. Change in genetic correlation due to selection using animal model evaluation.

    PubMed

    Strandén, I; Mäntysaari, E A; Mäki-Tanila, A

    1993-01-12

    Monte Carlo simulation and analytical calculations were used to study the effect of selection on genetic correlation between two traits. The simulated breeding program was based on a closed adult multiple ovulation and embryo transfer nucleus breeding scheme. Selection was on an index calculated using multi-trait animal model (AM). Analytical formulae applicable to any evaluation method were derived to predict change in genetic (co)variance due to selection under multi-trait selection using different evaluation methods. Two formulae were investigated, one assuming phenotypic selection and the other based on a recursive two-generation AM selection index. The recursive AM method approximated information due to relatives by a relationship matrix of two generations. Genetic correlation after selection was compared under different levels of initial genetic and environmental correlations with two different selection criteria. Changes in genetic correlation were similar in simulation and analytical predictions. After one round of selection the recursive AM method and the simulation gave similar predictions while the phenotypic selection predicted usually more change in genetic correlation. After several rounds of selection both analytical formulae predicted more change in genetic correlation than the simulation. ZUSAMMENFASSUNG: Änderung der genetischen Korrelation bei Selektion mit einem Tiermodell Der Selektionseffekt auf die genetische Korrelation zwischen zwei Merkmalen wurde mit Hilfe von Monte Carlo-Simulation und analytischen Berechnungen untersucht. Ein geschlossener Adulter - MOET (Multiple Ovulation and Embryo Transfer) Zuchtplan wurde simuliert. Die Selektion gründete sich auf einen Index, der die Zuchtwertschätzung des Mehrmerkmals-Tiermodells benutzte. Analytische Formeln für die Voraussage der Änderung der genetischen (Ko)varianz unter multivariate Selektion für verschiedene Zuchtwertschätzungsmethode wurden deduziert. Zwei Formeln wurden studiert

  11. Responses of isolator-derived Japanese quail and quail cell cultures to selected animal viruses.

    PubMed Central

    Farrow, W M; Schmitt, M W; Groupé, V

    1975-01-01

    Thirteen oncogenic and necrotizing animal viruses were assayed in LIFE Sciences, Inc. (LSI)-specific pathogen-free Japanese quail and LSI-specific pathogen-free chicken embryo cell cultures. Nine viruses produced similar titers in the quail and chicken cell systems, whereas four viruses showed significantly higher titers in chickens. Young Japanese quail and chickens were inoculated with five selected avain viruses and maintained in stainless-steel isolators. Comparable responses were noted in quail and chickens injected with Newcastle disease virus and avain leukosis virus, but quail were significantly more resistant than chickens to fowl pox virus, laryngotracheitis virus, and Marek's disease herpesvirus. Although no overt symptoms of disease were observed in Japanese quail inoculated with most avain viruses, neutralizing antibody or virus was detected, indicating presence of an inapparent infection. In one experiment, neutralizing antibody was detected in a comparable number of quail and chickens after inoculation with avian leukosis virus. Avian leukosis virus viremia was observed at 12 and 70 days postinoculation, with the COFAL (complement fixation for avian leukosis) titers similar for quail and chickens. Most quail infected with Marek's disease herpesvirus produced neutralizing antibody within 70 days but showed no classical symptoms of Marek's disease even when held for 5 months. In contrast, all chickens inoculated with Marek's disease herpesvirus died within 20 days. The utility of quail embryo cell cultured in the preparation of vaccines and biological reagents is discussed. PMID:172527

  12. Incorporating in situ habitat patchiness in site selection models reveals that site fidelity is not always a consequence of animal choice.

    PubMed

    Martinez, Aline S; Queiroz, Eduardo V; Bryson, Mitch; Byrne, Maria; Coleman, Ross A

    2017-03-25

    1.Understanding site fidelity is important in animal ecology, but evidence is lacking that this behaviour is due to an animal choosing a specific location. To discern site selection behaviour it is necessary to consider the spatial distribution of habitats that animals can occupy within a landscape. Tracking animals and defining clear habitat boundaries, however, is often difficult. 2.We use in situ habitat distribution data and animal movement simulations to investigate behavioural choice in site fidelity patterns. We resolved the difficulty of gathering data by working with intertidal rock pool systems, which are of manageable size and where boundaries are easy to define. Movements of the intertidal starfish Parvulastra exigua were quantified to test the hypotheses that (1) this species displays fidelity to a particular rock pool and that (2) rock pool fidelity is due to site selection behaviour. Observed patterns of individuals (n=10 starfish) returning to a previously occupied rock pool (n = 5 pools per location) were tested against an expected null distribution generated through simulations of random movements within their natural patchy environment. 3. Starfish exhibited site selection behaviour at only one location even though site fidelity was high (av. 7.4 starfish out of 10 found in test pools) in 2 of the 3 locations. The random chance of a starfish returning to a pool increased 67% for each metre further a rock pool was from the original pool, and 120% for each square metre increase in surface area of an original pool. The decision of returning to an original rock pool was influenced by food availability. When microalgal cover was > 60%, there was a ~ 50% chance of animals staying faithful to that pool. 4. Our results show the importance to consider spatial distribution of habitats in understanding patterns of animal movement associated with animal choices and site fidelity. Returning to a particular place does not necessarily mean that an

  13. From prebiotic chemistry to cellular metabolism--the chemical evolution of metabolism before Darwinian natural selection.

    PubMed

    Meléndez-Hevia, Enrique; Montero-Gómez, Nancy; Montero, Francisco

    2008-06-07

    It is generally assumed that the complex map of metabolism is a result of natural selection working at the molecular level. However, natural selection can only work on entities that have three basic features: information, metabolism and membrane. Metabolism must include the capability of producing all cellular structures, as well as energy (ATP), from external sources; information must be established on a material that allows its perpetuity, in order to safeguard the goals achieved; and membranes must be able to preserve the internal material, determining a selective exchange with external material in order to ensure that both metabolism and information can be individualized. It is not difficult to understand that protocellular entities that boast these three qualities can evolve through natural selection. The problem is rather to explain the origin of such features under conditions where natural selection could not work. In the present work we propose that these protocells could be built by chemical evolution, starting from the prebiotic primordial soup, by means of chemical selection. This consists of selective increases of the rates of certain specific reactions because of the kinetic or thermodynamic features of the process, such as stoichiometric catalysis or autocatalysis, cooperativity and others, thereby promoting their prevalence among the whole set of chemical possibilities. Our results show that all chemical processes necessary for yielding the basic materials that natural selection needs to work may be achieved through chemical selection, thus suggesting a way for life to begin.

  14. Natural selection on body size is mediated by multiple interacting factors: a comparison of beetle populations varying naturally and experimentally in body size

    PubMed Central

    Amarillo-Suárez, Angela R; Stillwell, R Craig; Fox, Charles W

    2011-01-01

    Body size varies considerably among species and among populations within species, exhibiting many repeatable patterns. However, which sources of selection generate geographic patterns, and which components of fitness mediate evolution of body size, are not well understood. For many animals, resource quality and intraspecific competition may mediate selection on body size producing large-scale geographic patterns. In two sequential experiments, we examine how variation in larval competition and resource quality (seed size) affects the fitness consequences of variation in body size in a scramble-competing seed-feeding beetle, Stator limbatus. Specifically, we compared fitness components among three natural populations of S. limbatus that vary in body size, and then among three lineages of beetles derived from a single base population artificially selected to vary in size, all reared on three sizes of seeds at variable larval density. The effects of larval competition and seed size on larval survival and development time were similar for larger versus smaller beetles. However, larger-bodied beetles suffered a greater reduction in adult body mass with decreasing seed size and increasing larval density; the relative advantage of being large decreased with decreasing seed size and increasing larval density. There were highly significant interactions between the effects of seed size and larval density on body size, and a significant three-way interaction (population-by-density-by-seed size), indicating that environmental effects on the fitness consequences of being large are nonadditive. Our study demonstrates how multiple ecological variables (resource availability and resource competition) interact to affect organismal fitness components, and that such interactions can mediate natural selection on body size. Studying individual factors influencing selection on body size may lead to misleading results given the potential for nonlinear interactions among selective agents

  15. Selective isolation of components from natural volatile oil by countercurrent chromatography with cyclodextrins as selective reagent.

    PubMed

    Tong, Shengqiang; Lu, Mengxia; Chu, Chu; Yan, Jizhong; Huang, Juan; Ying, Yongfei

    2016-04-29

    Selective separation of chemical components from seven kinds of volatile oil by countercurrent chromatography with three types of cyclodextrins as selective reagent was investigated in this work. Preparative separation of chemical components from volatile oil is generally quite challenging due to their extremely complexity of the composition. A biphasic solvent system n-hexane-0.10 mol L(-1) cyclodextrin (1:1, v/v) was selected for separation of components from volatile oil and three types of cyclodextrins were investigated, including β-cyclodexrin, methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin. All kinds of volatile oils are from seven kinds of traditional Chinese herb. Results showed that some chemical components could be well separated with high purity from each kind of volatile oil using different type of cyclodextrin as selective reagent. For example, germacrone and curcumenone could be selectively separated from volatile oil of Curcumae Rhizoma with methyl-β-cyclodexrin and hydroxypropyl-β-cyclodexrin as selector respectively, and other five components were selectively separated from volatile oil of Chuanxiong Rhizoma, Myristicae Semen, Aucklandiae Radix and Angelicae Sinensis Radix by countercurrent chromatography with different cyclodexrin as selective reagent. Separation mechanism for separation of components from volatile oil by countercurrent chromatography with cyclodextrin as selective reagent was proposed. Peak resolution of the present separation method could be greatly influenced by the chemical compositions of volatile oil. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Pixel selection for near-infrared chemical imaging (NIR-CI) discrimination between fish and terrestrial animal species in animal protein by-product meals.

    PubMed

    Riccioli, Cecilia; Pérez-Marín, Dolores; Guerrero-Ginel, José Emilio; Saeys, Wouter; Garrido-Varo, Ana

    2011-07-01

    This paper proposes a method based on near-infrared hyperspectral imaging for discriminating between terrestrial and fish species in animal protein by-products used in livestock feed. Four algorithms (Mahalanobis distance, Kennard-Stone, spatial interpolation, and binning) were compared in order to select an appropriate subset of pixels for further partial least squares discriminant analysis (PLS-DA). The method was applied to a set of 50 terrestrial and 40 fish meals analyzed in the 1000-1700 nm range. Models were then tested using an external validation set comprising 45 samples (25 fish and 20 terrestrial). The PLS-DA models obtained using the four subset-selection algorithms yielded a classification accuracy of 99.80%, 99.79%, 99.85%, and 99.61%, respectively. The results represent a first step for the analysis of mixtures of species and suggest that NIR-CI, providing valuable information on the origin of animal components in processed animal proteins, is a promising method that could be used as part of the EU feed control program aimed at eradicating and preventing bovine spongiform encephalopathy (BSE) and related diseases.

  17. The nature of X-ray selected star candidates

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.; Paronyan, G. M.; Abrahamyan, H. V.; Gigoyan, K. S.; Gyulzadyan, M. V.; Kostandyan, G. R.

    2016-12-01

    The joint HRC/BHRC catalogue of optical identifications of ROSAT BSC and FSC X-ray sources is based on merging the Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both have been made by optical identifications of X-ray sources based on low-dispersion spectra of the Hamburg Quasar Survey (HQS) using the ROSAT Catalogues. HRC/BHRC contains a sample of 8132 (5341+2791) optically identified X-ray sources with count rate (CR) of photons > 0.04 ct/s in the area of the low-dispersion Hamburg Quasar Survey (HQS), [b] > 20 and DEC > 0 degrees. Based on low-dispersion spectral classification, there are 4253 AGN, 492 galaxies, 1800 stars and 1587 unknown objects in the sample. 1800 star candidates include 1429 objects listed in SDSS DR12 photometric catalogue and 433 given in SDSS spectroscopic catalogue. Using these spectra, we have carried out classification of these star candidates to reveal new interesting objects, as well as to define the true content of our sample. 34 cataclysmic variables (including 7 new ones), 19 white dwarfs, 19 late-type stars (K-M and C types), 16 early type stars (O-B), 40 hot coronal stars (A-F types), 2 composite spectrum objects, and 17 bright stars have been revealed, as well as 286 objects which turned out to be extragalactic ones; 75 emission-line galaxies (HII/SB and AGN, including QSOs, Seyferts, and LINERs) and 211 absorption line galaxies were revealed (wrong classifications in HRC/BHRC due to their faint images and low-quality spectra). We have retrieved multiwavelength data from recent catalogues and carried out statistical investigations of the multiwavelength properties for the whole sample of stars. All stars have been found in GSC 2.3.2, as well as most of them are in GALEX, USNO-B1.0, 2MASS and WISE catalogues. Relations between the radiation fluxes in different bands from X-ray to radio for different types of sources are studied and analysis of their characteristics is made. X-ray selected stars are an

  18. Disruptive selection in natural populations: the roles of ecological specialization and resource competition.

    PubMed

    Martin, Ryan A; Pfennig, David W

    2009-08-01

    Disruptive selection is potentially critical in maintaining variation and initiating speciation. Yet there are few convincing examples of disruptive selection from nature. Moreover, relatively little is known about the causes of disruptive selection. Here, we document disruptive selection and its causes in natural populations of spadefoot toad tadpoles (Spea multiplicata), which are highly variable in trophic phenotype and resource use. Using a mark-recapture experiment in a natural pond, we show that selection favors extreme trophic phenotypes over intermediate individuals. We further show that such disruptive selection likely reflects both ecological specialization and resource competition. Evidence for ecological specialization comes from two field experiments, which demonstrate that extreme phenotypes forage more effectively on the main alternative resource types. Support for competition's role in disruptive selection comes from two additional experiments, which demonstrate that intermediate phenotypes, which are often the most common phenotype, compete more with each other than with extreme forms and that the intensity of disruptive selection increases with conspecific density. Generally, ecological specialization and competition are widespread, suggesting that many populations may experience some level of disruptive selection. Thus, disruptive selection may be a more common force contributing to phenotypic variation in natural populations than is currently recognized.

  19. Assessing the alignment of sexual and natural selection using radiomutagenized seed beetles.

    PubMed

    Power, D J; Holman, L

    2015-05-01

    A major unsolved question in evolutionary biology concerns the relationship between natural and sexual selection. Sexual selection might augment natural selection, for example if mutations that harm female fecundity also reduce male mating success. Conversely, sexual selection might favour traits that impair naturally selected fitness components. We induced detrimental mutations in Callosobruchus maculatus beetles using X-ray irradiation and then experimentally measured the effect of precopulatory sexual selection on offspring number and survival rate. Sexual selection treatment had a negative effect on egg-to-adult survivorship, although the number of progeny reaching adulthood was unaffected, perhaps because eggs and juveniles that failed to develop lessened competition on the survivors. We hypothesize that the negative effect of sexual selection arose because sexually competitive males transmitted a smaller nuptial gift or carried alleles that conferred reduced survival. Although we found no evidence that sexual selection on males can purge alleles that are detrimental to naturally selected fitness components, such benefits might exist in other environmental or genetic contexts.

  20. Tribology studies of the natural knee using an animal model in a new whole joint natural knee simulator.

    PubMed

    Liu, Aiqin; Jennings, Louise M; Ingham, Eileen; Fisher, John

    2015-09-18

    The successful development of early-stage cartilage and meniscus repair interventions in the knee requires biomechanical and biotribological understanding of the design of the therapeutic interventions and their tribological function in the natural joint. The aim of this study was to develop and validate a porcine knee model using a whole joint knee simulator for investigation of the tribological function and biomechanical properties of the natural knee, which could then be used to pre-clinically assess the tribological performance of cartilage and meniscal repair interventions prior to in vivo studies. The tribological performance of standard artificial bearings in terms of anterior-posterior (A/P) shear force was determined in a newly developed six degrees of freedom tribological joint simulator. The porcine knee model was then developed and the tribological properties in terms of shear force measurements were determined for the first time for three levels of biomechanical constraints including A/P constrained, spring force semi-constrained and A/P unconstrained conditions. The shear force measurements showed higher values under the A/P constrained condition (predominantly sliding motion) compared to the A/P unconstrained condition (predominantly rolling motion). This indicated that the shear force simulation model was able to differentiate between tribological behaviours when the femoral and tibial bearing was constrained to slide or/and roll. Therefore, this porcine knee model showed the potential capability to investigate the effect of knee structural, biomechanical and kinematic changes, as well as different cartilage substitution therapies on the tribological function of natural knee joints.

  1. Lipids in selected abyssal benthopelagic animals: links to the epipelagic zone?

    NASA Astrophysics Data System (ADS)

    Bühring, Solveig I.; Christiansen, Bernd

    A detailed study of the lipids of selected zooplankton species and scavenging amphipods in the near-bottom water layer (15-100 m above bottom, mab) was carried out at the BENGAL site in late summer 1998. Copepoda were the main contributors to the zooplankton, comprising 75% of the total abundance, followed by Ostracoda and Chaetognatha. Calanoid copepods of the family Metridinidae were predominant and accounted for more than 50% of all copepods. Two types of storage lipids were distinguished: triacylglycerols and wax esters. Ostracoda and the polychaete Vanadis sp. stored exclusively triacylglycerols whilst the bulk of the Copepoda accumulated wax esters, with the exception of the family Aetideidae. In the amphipods both lipid classes were found: Eurythenes gryllus stored wax esters and Paralicella spp. and Orchomene sp. triacylglycerols. The fatty acid composition was characterized by a high level of monounsaturated 18:1 ( n-9), which is described as characteristic for animals living in the deeper layers of the water column, and to a lesser degree by 16:1 ( n-7) and 20:5 ( n-3), which are typical components of diatom lipids, and 22:6 ( n-3), typical of dinoflagellates. The ratio of 18:1 ( n-9):18:1 ( n-7) fatty acids was between 5 and 10 in the copepods and indicates a carnivorous/omnivorous feeding behaviour in this group, whereas the higher ratios of 8-18 in the amphipods confirm their necrophagy. The fatty alcohols of the animals storing wax esters were dominated by the monounsaturated isomers 18:1 ( n-9) and 18:1 ( n-7). The predominance of wax esters as storage lipids in the deep-sea copepods indicates a strong seasonality in the availability of food. This is supported by the high levels of 16:1 ( n-7), 20:5 ( n-3) and 22:6 ( n-3) fatty acids, which point to there being a direct link between the surface primary production and deep-sea copepods, probably via the rapid deposition of phytodetritus.

  2. Concentration-mortality responses of Myzus persicae and natural enemies to selected insecticides.

    PubMed

    Bacci, Leandro; Rosado, Jander F; Picanço, Marcelo C; Pereira, Eliseu J G; Silva, Gerson A; Martins, Júlio C

    2012-01-01

    The toxicity of six insecticides was determined for the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae), and some of its natural enemies - the predatory beetles Cycloneda sanguinea (Coccinellidae) and Acanthinus sp. (Anthicidae), and the wasp parasitoid Diaeretiella rapae (Aphidiidae). Natural enemies from these groups are important natural biological control agents in a number of agroecosystems, and insecticides potentially safe to these non-target organisms should be identified using standardized tests. Thus, concentration-mortality bioassays were carried out with both the aphid and its natural enemies to assess the toxicity and selectivity of acephate, deltamethrin, dimethoate, methamidophos, methyl parathion, and pirimicarb. The latter insecticide was highly selective to all natural enemies tested, and its LC(90) for M. persicae was 14-fold lower than the field rate recommended for control of the aphid in brassica crops. Methyl parathion also showed selectivity to C. sanguinea and Acanthinus sp., but not to D. rapae. Acephate was the least potent insecticide against M. persicae and was equally or more toxic to the natural enemies relative to the aphid. Pirimicarb and methyl parathion were efficient against M. persicae and selective in favor of two of the natural enemies tested. Acanthinus sp. and C. sanguinea were more tolerant to the insecticides than was the parasitoid D. rapae. This study shows that there are selective insecticides that may be compatible with conservation of natural enemies in brassica crops, which is important practical information to improve integrated pest management systems in these crops.

  3. How could it be? calling for science curricula that cultivate morals and values towards other animals and nature

    NASA Astrophysics Data System (ADS)

    Logan, Marianne R.; Russell, Joshua J.

    2016-12-01

    Can science curricula truly cultivate morals and values towards nature? This is the question that is raised by Carolina Castano Rodriguez in her critique of the new Australian Science curriculum. In this response to Castano Rodriguez's paper we ask two questions relating to: the influence of curricula on the relationships of children and other animals; and other models of science education regarding animals and nature that may be more relevant, just, or caring. In responding to these questions stimulated by the reading of Castano Rodriguez's paper, we reflect on our own experiences. We note the conflict between the values depicted in the curriculum priorities and the underlying anthropocentric view that appears to be embedded in the Australian Science Curriculum and in curricula generally. With this conflict in mind we encourage educators to examine our own practices regarding how the relationships between humans and other animals are promoted. We put forward the idea of science education that responds to the shifting views of science and its applications outside the confines of the laboratory to one that encourages both ethical and political discussion that is already taking place in the community relating to the role of science and technology in our lives and the lives of other animals.

  4. Animal and vegetation patterns in natural and man-made bog pools: implications for restoration

    USGS Publications Warehouse

    Mazerolle, M.J.; Poulin, M.; Lavoie, C.; Rochefort, L.; Desrochers, A.; Drolet, B.

    2006-01-01

    1. Peatlands have suffered great losses following drainage for agriculture, forestry, urbanisation, or peat mining, near inhabited areas. We evaluated the faunal and vegetation patterns after restoration of a peatland formerly mined for peat. We assessed whether bog pools created during restoration are similar to natural bog pools in terms of water chemistry, vegetation structure and composition, as well as amphibian and arthropod occurrence patterns. 2. Both avian species richness and peatland vegetation cover at the site increased following restoration. Within bog pools, however, the vegetation composition differed between natural and man-made pools. The cover of low shrubs, Sphagnum moss, submerged, emergent and floating vegetation in man-made pools was lower than in natural pools, whereas pH was higher than in typical bog pools. Dominant plant species also differed between man-made and natural pools. 3. Amphibian tadpoles, juveniles and adults occurred more often in man-made pools than natural bog pools. Although some arthropods, including Coleoptera bog specialists, readily colonised the pools, their abundance was two to 26 times lower than in natural bog pools. Plant introduction in bog pools, at the stocking densities we applied, had no effect on the occurrence of most groups. 4. We conclude that our restoration efforts were partially successful. Peatland-wide vegetation patterns following restoration mimicked those of natural peatlands, but 4 years were not sufficient for man-made pools to fully emulate the characteristics of natural bog pools.

  5. Opportunity for natural selection among some selected population groups of Northeast India

    PubMed Central

    Das, Farida Ahmed; Mithun, Sikdar

    2010-01-01

    BACKGROUND: Selection potential based on differential fertility and mortality has been computed for seven population groups inhabiting different geographical locations of Northeast India. MATERIALS AND METHODS: Crow’s as well as Johnston and Kensinger’s index have been used for the present purpose. RESULTS AND CONCLUSION: Irrespective of the methodology, the total index of selection was found to be highest among the Deoris followed by the Kaibartas. The lowest selection index was found among the Oraon population. If the relative contribution of fertility and mortality components to the total index is considered to be multiplicative, it is observed that in all these communities the fertility component exceeds that of mortality component, which may indicate initiation of demographic transitional phase in the selected populations with the betterment of healthcare and socioeconomic condition within the last few decades. PMID:21031053

  6. Synergistic combinatorial antihyperlipidemic study of selected natural antioxidants; modulatory effects on lipid profile and endogenous antioxidants.

    PubMed

    Hannan, Peer Abdul; Khan, Jamshaid Ali; Ullah, Irfan; Ullah, Safi

    2016-09-09

    Hyperlipidemia, a major pathological condition associated with disrupted lipid levels and physiological redox homeostasis. The excessive release of reactive oxygen species (ROS) leads to enhanced lipid peroxidation, aggravated atherosclerosis and oxidative stress. Integration of natural antioxidant blends in alone or with conventional treatments can alleviate these issues synergistically contributing least side effects. Published literature reported the efficacy of natural antioxidants as individual and in combinations in various conditions but less data is available on their evaluation in low dose ratio blends particularly in hypercholesterolemic diet. Antihyperlipidemic effects of selected natural antioxidants; the phenolic oligomeric proanthocyanidins (OPC) and pterostilbene (PT) with niacin (NA) were investigated in current study. Their effects on lipid profile, lipid peroxidation and their aptitude to establish redox state between oxidants and antioxidants in body were evaluated in high cholesterol diet fed animal model. Male albino rabbits (n = 6) weighing 1.2-1.6 kg, supplemented with high cholesterol diet (400 mg/kg) for 12 weeks were used in the experiment. Antioxidants were administered individual high (100 mg/kg) and in low dose combinations (total dose = 100 mg/kg). Student's t test and one way analysis of variance (ANOVA) followed by Dunnet's test were used as statistical tools for evaluation. The results showed synergistic effects of low dose antioxidant blends. Therapies retarded elevation in blood lipid levels, lipid peroxidation and blood antioxidant depletion and consequently contributed in reestablishing redox homeostasis. The LDL/HDL ratio and atherogenic index were suppressed significantly in blend therapies with maximum effects of 59.3 and 25 % (p >0.001) observed in 50:30:20 ratios of OPC, NA and PT, compared to individual therapies 37 and 18 % max respectively. Moreover the results were also in close proximity with the statin

  7. The transcriptional consequences of mutation and natural selection in Caenorhabditis elegans.

    PubMed

    Denver, Dee R; Morris, Krystalynne; Streelman, J Todd; Kim, Stuart K; Lynch, Michael; Thomas, W Kelley

    2005-05-01

    The evolutionary importance of gene-expression divergence is unclear: some studies suggest that it is an important mechanism for evolution by natural selection, whereas others claim that most between-species regulatory changes are neutral or nearly neutral. We examined global transcriptional divergence patterns in a set of Caenorhabditis elegans mutation-accumulation lines and natural isolate lines to provide insights into the evolutionary importance of transcriptional variation and to discriminate between the forces of mutation and natural selection in shaping the evolution of gene expression. We detected the effects of selection on transcriptional divergence patterns and characterized them with respect to coexpressed gene sets, chromosomal clustering of expression changes and functional gene categories. We directly compared observed transcriptional variation patterns in the mutation-accumulation and natural isolate lines to a neutral model of transcriptome evolution to show that strong stabilizing selection dominates the evolution of transcriptional change for thousands of C. elegans expressed sequences.

  8. The Darwin cure for apiculture? Natural selection and managed honeybee health.

    PubMed

    Neumann, Peter; Blacquière, Tjeerd

    2017-03-01

    Recent major losses of managed honeybee, Apis mellifera, colonies at a global scale have resulted in a multitude of research efforts to identify the underlying mechanisms. Numerous factors acting singly and/or in combination have been identified, ranging from pathogens, over nutrition to pesticides. However, the role of apiculture in limiting natural selection has largely been ignored. This is unfortunate, because honeybees are more exposed to environmental stressors compared to other livestock and management can severely compromise bee health. Here, we briefly review apicultural factors that influence bee health and focus on those most likely interfering with natural selection, which offers a broad range of evolutionary applications for field practice. Despite intense breeding over centuries, natural selection appears to be much more relevant for the health of managed A. mellifera colonies than previously thought. We conclude that sustainable solutions for the apicultural sector can only be achieved by taking advantage of natural selection and not by attempting to limit it.

  9. Young children can be taught basic natural selection using a picture-storybook intervention.

    PubMed

    Kelemen, Deborah; Emmons, Natalie A; Seston Schillaci, Rebecca; Ganea, Patricia A

    2014-04-01

    Adaptation by natural selection is a core mechanism of evolution. It is also one of the most widely misunderstood scientific processes. Misconceptions are rooted in cognitive biases found in preschoolers, yet concerns about complexity mean that adaptation by natural selection is generally not comprehensively taught until adolescence. This is long after untutored theoretical misunderstandings are likely to have become entrenched. In a novel approach, we explored 5- to 8-year-olds' capacities to learn a basic but theoretically coherent mechanistic explanation of adaptation through a custom storybook intervention. Experiment 1 showed that children understood the population-based logic of natural selection and also generalized it. Furthermore, learning endured 3 months later. Experiment 2 replicated these results and showed that children understood and applied an even more nuanced mechanistic causal explanation. The findings demonstrate that, contrary to conventional educational wisdom, basic natural selection is teachable in early childhood. Theory-driven interventions using picture storybooks with rich explanatory structure are beneficial.

  10. Classroom Companions: A Nature-Lover's Case for Bringing Animals Back into the Classroom

    ERIC Educational Resources Information Center

    Bartlett, Cindy

    2006-01-01

    In this article, the author relates her experiences in sharing her love of animals with her students. She observes how some children who struggled with reading would risk reading passages aloud when given the opportunity to hold a rabbit, and how students seemed to come alive as they interacted with or included the rabbit in a writing piece. She…

  11. Classroom Companions: A Nature-Lover's Case for Bringing Animals Back into the Classroom

    ERIC Educational Resources Information Center

    Bartlett, Cindy

    2006-01-01

    In this article, the author relates her experiences in sharing her love of animals with her students. She observes how some children who struggled with reading would risk reading passages aloud when given the opportunity to hold a rabbit, and how students seemed to come alive as they interacted with or included the rabbit in a writing piece. She…

  12. Ticks collected from wild and domestic animals and natural habitats in the Republic of Korea.

    PubMed

    Kim, Baek-Jun; Kim, Hyewon; Won, Sohyun; Kim, Heung-Chul; Chong, Sung-Tae; Klein, Terry A; Kim, Ki-Gyoung; Seo, Hong-Yul; Chae, Joon-Seok

    2014-06-01

    Ticks were collected from 35 animals from 5 provinces and 3 metropolitan cities during 2012. Ticks also were collected by tick drag from 4 sites in Gyeonggi-do (2) and Jeollabuk-do (2) Provinces. A total of 612 ticks belonging to 6 species and 3 genera were collected from mammals and a bird (n=573) and by tick drag (n=39). Haemaphyalis longicornis (n=434) was the most commonly collected tick, followed by H. flava (158), Ixodes nipponensis (11), Amblyomma testudinarium (7), H. japonica (1), and H. formosensis (1). H. longicornis and H. flava were collected from all animal hosts examined. For animal hosts (n>1), the highest Tick Index (TI) was observed for domestic dogs (29.6), followed by Siberian roe deer (17.4), water deer (14.4), and raccoon dogs (1.3). A total of 402 H. longicornis (adults 86, 21.4%; nymphs 160, 39.8%; larvae 156, 38.9%) were collected from wild and domestic animals. A total of 158 H. flava (n=158) were collected from wild and domestic animals and 1 ring-necked pheasant, with a higher proportion of adults (103, 65.2%), while nymphs and larvae only accounted for 12.7% (20) and 22.2% (35), respectively. Only 7 A. testudinarium were collected from the wild boar (6 adults) and Eurasian badger (1 nymph), while only 5 I. nipponensis were collected from the water deer (4 adults) and a raccoon dog (1 adult). One adult female H. formosensis was first collected from vegetation by tick drag from Mara Island, Seogwipo-si, Jeju-do Province.

  13. Phytochemicals in animal health: diet selection and trade-offs between costs and benefits.

    PubMed

    Villalba, Juan J; Costes-Thiré, Morgane; Ginane, Cécile

    2017-05-01

    Many plant tissues contain plant secondary compounds (PSC), which have long been recognised as defensive chemicals that deter herbivory via their toxic effects. However, herbivores may also benefit from including PSC into their diets. Plant-derived phenolics, terpenes and alkaloids have antiparasitic properties and sesquiterpene lactones have antibacterial, antifungal and antiparasitic properties. These actions are in part a consequence of the negative actions that PSC exert across several trophic levels, including the bacteria, parasites and fungi that inhabit herbivores' bodies. Given the dual action, toxin and medicine, it is possible to hypothesise that self-selection of PSC by herbivores should occur when the benefits outweigh the costs of PSC ingestion. Recent research suggests that sheep and goats self-medicate against parasitic infections. They increase preference for condensed tannin-containing foods when experiencing a parasitic burden. This behaviour improves health; it is triggered by parasitism and weakens when parasitism subsides. However, the causes underlying these responses are not straightforward when viewed under a unidimensional cost-benefit analysis. This is because the intensity of antinutritional/toxic and medicinal effects of PSC is not static or just dependent upon the isolated post-ingestive effects of single PSC. Nutrient-PSC and PSC-PSC interactions, social models, as well as feeding patterns, all influence the perceived net benefit of incorporating medicines into a diet. A better understanding of the net benefit of self-medication in complex feeding environments will allow for the development of innovative managing strategies aimed at providing the food alternatives and conditions for improving the nutrition, health and welfare of grazing animals.

  14. Selective cytoprotective effect of histamine on doxorubicin-induced hepatic and cardiac toxicity in animal models

    PubMed Central

    Lamas, DJMartinel; Nicoud, MB; Sterle, HA; Carabajal, E; Tesan, F; Perazzo, JC; Cremaschi, GA; Rivera, ES; Medina, VA

    2015-01-01

    The aim of the present work was to evaluate the potential protective effect of histamine on Doxorubicin (Dox)-induced hepatic and cardiac toxicity in different rodent species and in a triple-negative breast tumor-bearing mice model. Male Sprague Dawley rats and Balb/c mice were divided into four groups: control (received saline), histamine (5 mg/kg for rats and 1 mg/kg for mice, daily subcutaneous injection starting 24 h before treatment with Dox), Dox (2 mg/kg, intraperitoneally injected three times a week for 2 weeks) and Dox+histamine (received both treatments). Tissue toxicity was evaluated by histopathological studies and oxidative stress and biochemical parameters. The combined effect of histamine and Dox was also investigated in vitro and in vivo in human MDA-MB-231 triple-negative breast cancer model. Heart and liver of Dox-treated animals displayed severe histological damage, loss of tissue weight, increased TBARS levels and DNA damage along with an augment in serum creatine kinase-myocardial band. Pretreatment with histamine prevented Dox-induced tissue events producing a significant preservation of the integrity of both rat and mouse myocardium and liver, through the reduction of Dox-induced oxidative stress and apoptosis. Histamine treatment preserved anti-tumor activity of Dox, exhibiting differential cytotoxicity and increasing the Dox-induced inhibition of breast tumor growth. Findings provide preclinical evidence indicating that histamine could be a promising candidate as a selective cytoprotective agent for the treatment of Dox-induced cardiac and hepatic toxicity, and encourage the translation to clinical practice. PMID:27551485

  15. Epistasis and natural selection shape the mutational architecture of complex traits.

    PubMed

    Jones, Adam G; Bürger, Reinhard; Arnold, Stevan J

    2014-05-14

    The evolutionary trajectories of complex traits are constrained by levels of genetic variation as well as genetic correlations among traits. As the ultimate source of all genetic variation is mutation, the distribution of mutations entering populations profoundly affects standing variation and genetic correlations. Here we use an individual-based simulation model to investigate how natural selection and gene interactions (that is, epistasis) shape the evolution of mutational processes affecting complex traits. We find that the presence of epistasis allows natural selection to mould the distribution of mutations, such that mutational effects align with the selection surface. Consequently, novel mutations tend to be more compatible with the current forces of selection acting on the population. These results suggest that in many cases mutational effects should be seen as an outcome of natural selection rather than as an unbiased source of genetic variation that is independent of other evolutionary processes.

  16. Natural selection constrains neutral diversity across a wide range of species.

    PubMed

    Corbett-Detig, Russell B; Hartl, Daniel L; Sackton, Timothy B

    2015-04-01

    The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics.

  17. Natural Selection Constrains Neutral Diversity across A Wide Range of Species

    PubMed Central

    Corbett-Detig, Russell B.; Hartl, Daniel L.; Sackton, Timothy B.

    2015-01-01

    The neutral theory of molecular evolution predicts that the amount of neutral polymorphisms within a species will increase proportionally with the census population size (Nc). However, this prediction has not been borne out in practice: while the range of Nc spans many orders of magnitude, levels of genetic diversity within species fall in a comparatively narrow range. Although theoretical arguments have invoked the increased efficacy of natural selection in larger populations to explain this discrepancy, few direct empirical tests of this hypothesis have been conducted. In this work, we provide a direct test of this hypothesis using population genomic data from a wide range of taxonomically diverse species. To do this, we relied on the fact that the impact of natural selection on linked neutral diversity depends on the local recombinational environment. In regions of relatively low recombination, selected variants affect more neutral sites through linkage, and the resulting correlation between recombination and polymorphism allows a quantitative assessment of the magnitude of the impact of selection on linked neutral diversity. By comparing whole genome polymorphism data and genetic maps using a coalescent modeling framework, we estimate the degree to which natural selection reduces linked neutral diversity for 40 species of obligately sexual eukaryotes. We then show that the magnitude of the impact of natural selection is positively correlated with Nc, based on body size and species range as proxies for census population size. These results demonstrate that natural selection removes more variation at linked neutral sites in species with large Nc than those with small Nc and provides direct empirical evidence that natural selection constrains levels of neutral genetic diversity across many species. This implies that natural selection may provide an explanation for this longstanding paradox of population genetics. PMID:25859758

  18. Critical-like self-organization and natural selection: two facets of a single evolutionary process?

    PubMed

    Halley, Julianne D; Winkler, David A

    2008-05-01

    We argue that critical-like dynamics self-organize relatively easily in non-equilibrium systems, and that in biological systems such dynamics serve as templates upon which natural selection builds further elaborations. These critical-like states can be modified by natural selection in two fundamental ways, reflecting the selective advantage (if any) of heritable variations either among avalanche participants or among whole systems. First, reproducing (avalanching) units can differentiate, as units adopt systematic behavioural variations. Second, whole systems that are exposed to natural selection can become increasingly or decreasingly critical. We suggest that these interactions between SOC-like dynamics and natural selection have profound consequences for biological systems because they could have facilitated the evolution of division of labour, compartmentalization and computation, key features of biological systems. The logical conclusion of these ideas is that the fractal geometry of nature is anything but coincidental, and that natural selection is itself a fractal process, occurring on many temporal and spatial scales.

  19. Darwinian agriculture: when can humans find solutions beyond the reach of natural selection?

    PubMed

    Denison, R Ford; Kiers, E Toby; West, Stuart A

    2003-06-01

    Progress in genetic improvement of crop yield potential has slowed since 1985. Simultaneously, more sustainable management of agricultural ecosystems is needed. A better understanding of natural selection can help solve both problems. We illustrate this point with two specific examples. First, the genetic legacy of crop plants has been refined by millions of years of natural selection, often driven by competition among plants. We therefore suggest that most simple, tradeoff-free options to increase competitiveness (e.g., increased gene expression, or minor modifications of existing plant genes) have already been tested by natural selection. Further genetic improvement of crop yield potential over the next decade will mainly involve tradeoffs, either between fitness in past versus present environments, or between individual competitiveness and the collective performance of plant communities. Eventually, we may develop the ability to predict the consequences of genetic alterations so radical that they have not yet been tested by natural selection. Second, natural selection acts mainly at the level of genes, individuals, and family groups, rather than ecosystems as a whole. Consequently, there is no reason to expect the structure of natural ecosystems (diversity, spatial, or temporal patterns) to be a reliable blueprint for agricultural ecosystems. Natural ecosystems are nonetheless an important source of information that could be used to improve agriculture.

  20. ANTI-ULCEROGENIC EFFICACY AND MECHANISMS OF EDIBLE AND NATURAL INGREDIENTS IN NSAID-INDUCED ANIMAL MODELS

    PubMed Central

    Bi, Weiping; Hu, Lizhi; Man, Mao-Qiang

    2017-01-01

    Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of the most commonly used medicines and proven to be effective for certain disorders. Some people use NSAIDs on daily basis for preventive purpose. But a variety of severe side effects can be induced by NSAIDs. Studies have shown that edible natural ingredients exhibit preventive benefit of gastric ulcer. This paper reviews the efficacy and safety of edible natural ingredients in preventing the development of gastric ulcer induced by NSAIDs in animal models. Methods: A systematic literature search was conducted on PubMed, using the terms “herbal medicines” and “gastric ulcer”, “herbal medicines” and “peptic ulcer”, “food” and “peptic ulcer”, “food” and “gastric ulcer”, “natural ingredient” and “peptic ulcer”, “natural ingredient” and “gastric ulcer”, “alternative medicine” and “peptic ulcer”, “alternative medicine” and “gastric ulcer”, “complementary medicine” and “peptic ulcer”, “complementary medicine” and “gastric ulcer” in papers published in English between January 1, 1960 and January 31, 2016, resulting in a total of 6146 articles containing these terms. After exclusion of studies not related prevention, not in NSAID model or using non-edible natural ingredients, 54 articles were included in this review. Results: Numerous studies have demonstrated that edible natural ingredients exhibit antiulcerogenic benefit in NSAID-induced animal models. The mechanisms by which edible, ingredient-induced anti-ulcerogenic effects include stimulation of mucous cell proliferation, antioxidation, inhibition of gastric acid secretion, as well as inhibition of H (+), K (+)- ATPase activities. Utilization of edible, natural ingredients could be a safe, valuable alternative to prevent the development of NSAID-induced gastric ulcer, particularly for the subjects who are long-term users of NSAIDs. PMID:28638885

  1. Considerations for the selection of a generator as a back-up power source for an animal facility.

    PubMed

    Stich, Elizabeth B

    2013-10-01

    Loss of power, whether or not it is related to a disaster, is a potential problem for animal facilities. The lack of light and the inability to operate mechanical systems related to ventilation, security, access, water, sewer and environmental control; to use laboratory instruments and equipment such as cage-washers and automatic watering systems; and to access computers and electronic files, potentially including animal health records and environmental monitoring data, present substantial challenges to facility operation. Therefore, an animal research facility must develop a contingency plan to address loss of power and other potential threats. Use of a back-up power source such as a generator is a common component of such a plan. Here the author discusses factors that should be considered in the selection of a generator as a back-up power source for an animal facility.

  2. Can more be learned from selection experiments of value in animal breeding programmes? Or is it time for an obituary?

    PubMed

    Hill, W G

    2011-04-01

    Selection experiments in laboratory animals and livestock have provided a wealth of information on genetic parameters of quantitative traits and on the effectiveness of selection in the short and long term on both directly selected and correlated traits. They have stimulated developments in theory and tests of it, and extreme selected lines continue to be source material for biological study. Some of the main questions and findings are briefly reviewed. Yet much of successful animal breeding practice has been based essentially on statistical methods, assuming where necessary the infinitesimal model, and new developments such as genomic selection are similarly not based on selection experiments. Information on the genetic architecture of quantitative traits is provided by selection experiments, but new methods for deeper studies of the biology are available. I discuss the future role for selection experiments in view of changes in funding streams and technology and conclude that there is little case for starting new experiments, but retention of existing long-term lines is desirable and DNA should be collected from all lines on a continuing basis.

  3. Selected References and Aids for Teaching Animal Science to Students of Agricultural Education.

    ERIC Educational Resources Information Center

    Miller, Larry E.

    The resource guide for animal science education is divided into six subject areas: general animal science, beef, dairy, poultry, sheep, and swine. Within each of these areas, the guide provides bibliographic and availability data for relevant materials in the following forms: bulletins and circulars; textbooks; films, filmstrips, and slides; and…

  4. Four decades of opposing natural and human-induced artificial selection acting on Windermere pike (Esox lucius).

    PubMed

    Carlson, Stephanie M; Edeline, Eric; Asbjørn Vøllestad, L; Haugen, Thrond O; Winfield, Ian J; Fletcher, Janice M; Ben James, J; Stenseth, Nils Chr

    2007-06-01

    The ability of natural selection to drive local adaptation has been appreciated ever since Darwin. Whether human impacts can impede the adaptive process has received less attention. We tested this hypothesis by quantifying natural selection and harvest selection acting on a freshwater fish (pike) over four decades. Across the time series, directional natural selection tended to favour large individuals whereas the fishery targeted large individuals. Moreover, non-linear natural selection tended to favour intermediate sized fish whereas the fishery targeted intermediate sized fish because the smallest and largest individuals were often not captured. Thus, our results unequivocally demonstrate that natural selection and fishery selection often acted in opposite directions within this natural system. Moreover, the two selective factors combined to produce reduced fitness overall and stronger stabilizing selection relative to natural selection acting alone. The long-term ramifications of such human-induced modifications to adaptive landscapes are currently unknown and certainly warrant further investigation.

  5. Notice of release of Amethyst Germplasm hoaty tansyaster: Selected class of natural germplasm

    Treesearch

    Derek J. Tilley

    2015-01-01

    The US Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS), Aberdeen Plant Materials Center, Aberdeen, Idaho, announces the release of Amethyst Germplasm hoary tansyaster (Machaeronthero canescens (Pursh) A. Gray [Asteraceae]}, a selected class natural track germplasm identified by NRCS accession number 9076670 for conservation plantings in...

  6. Naturally seeded versus planted ponderosa pine seedlings in group-selection openings

    Treesearch

    Philip M. McDonald; Gary Fiddler; Martin Ritchie; Paula Anderson

    2009-01-01

    The purpose of this article was to determine whether natural regeneration or planted seedlings should be used in group-selection openings. The answer dependson the survival and growth rate of both types of seedlings, and that could depend on the size of the openings and the effect of trees on their edge. In thisside-by-side study, the natural pine seedlings originated...

  7. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    ERIC Educational Resources Information Center

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-01-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also…

  8. From Ends to Causes (and Back Again) by Metaphor: The Paradox of Natural Selection

    ERIC Educational Resources Information Center

    Blancke, Stefaan; Schellens, Tammy; Soetaert, Ronald; Van Keer, Hilde; Braeckman, Johan

    2014-01-01

    Natural selection is one of the most famous metaphors in the history of science. Charles Darwin used the metaphor and the underlying analogy to frame his ideas about evolution and its main driving mechanism into a full-fledged theory. Because the metaphor turned out to be such a powerful epistemic tool, Darwin naturally assumed that he could also…

  9. Mycoflora and Natural Incidence of Selected Mycotoxins in Rabbit and Chinchilla Feeds

    PubMed Central

    Greco, Mariana Vanesa; Pardo, Alejandro Guillermo; Ludemann, Vanesa; Martino, Pablo Eduardo; Pose, Graciela Noemí

    2012-01-01

    Mycotoxins are secondary metabolites produced by filamentous fungi that cause a toxic response when ingested by animals or man. Demand of natural fur, such as those from rabbit and chinchilla, produced under controlled conditions, has increased worldwide. The toxicogenic mycoflora contaminating feeds for these animals was enumerated and identified. Six of the major mycotoxins implicated in animal mycotoxicosis were detected and quantified. Moulds count ranged from <10 to 4.7 × 105 CFU g−1; 14% of the samples exceeded the limit that determines hygienic feed quality. More than twenty species belonging to the five most important mycotoxigenic mould genera were recovered. Among the analyzed mycotoxins, aflatoxins were recovered in 100% of the examined samples, deoxynivalenol in 95%, fumonisins in 100%, ochratoxin A in 98%, T2 toxin in 98%, and zearalenone in 100%. Cooccurrence of mycotoxins was observed in 100% of the samples analyzed. Exposure to multiple mycotoxins was thus demonstrated for these animals. PMID:22649328

  10. Forest fragmentation and selective logging have inconsistent effects on multiple animal-mediated ecosystem processes in a tropical forest.

    PubMed

    Schleuning, Matthias; Farwig, Nina; Peters, Marcell K; Bergsdorf, Thomas; Bleher, Bärbel; Brandl, Roland; Dalitz, Helmut; Fischer, Georg; Freund, Wolfram; Gikungu, Mary W; Hagen, Melanie; Garcia, Francisco Hita; Kagezi, Godfrey H; Kaib, Manfred; Kraemer, Manfred; Lung, Tobias; Naumann, Clas M; Schaab, Gertrud; Templin, Mathias; Uster, Dana; Wägele, J Wolfgang; Böhning-Gaese, Katrin

    2011-01-01

    Forest fragmentation and selective logging are two main drivers of global environmental change and modify biodiversity and environmental conditions in many tropical forests. The consequences of these changes for the functioning of tropical forest ecosystems have rarely been explored in a comprehensive approach. In a Kenyan rainforest, we studied six animal-mediated ecosystem processes and recorded species richness and community composition of all animal taxa involved in these processes. We used linear models and a formal meta-analysis to test whether forest fragmentation and selective logging affected ecosystem processes and biodiversity and used structural equation models to disentangle direct from biodiversity-related indirect effects of human disturbance on multiple ecosystem processes. Fragmentation increased decomposition and reduced antbird predation, while selective logging consistently increased pollination, seed dispersal and army-ant raiding. Fragmentation modified species richness or community composition of five taxa, whereas selective logging did not affect any component of biodiversity. Changes in the abundance of functionally important species were related to lower predation by antbirds and higher decomposition rates in small forest fragments. The positive effects of selective logging on bee pollination, bird seed dispersal and army-ant raiding were direct, i.e. not related to changes in biodiversity, and were probably due to behavioural changes of these highly mobile animal taxa. We conclude that animal-mediated ecosystem processes respond in distinct ways to different types of human disturbance in Kakamega Forest. Our findings suggest that forest fragmentation affects ecosystem processes indirectly by changes in biodiversity, whereas selective logging influences processes directly by modifying local environmental conditions and resource distributions. The positive to neutral effects of selective logging on ecosystem processes show that the

  11. Forest Fragmentation and Selective Logging Have Inconsistent Effects on Multiple Animal-Mediated Ecosystem Processes in a Tropical Forest

    PubMed Central

    Schleuning, Matthias; Farwig, Nina; Peters, Marcell K.; Bergsdorf, Thomas; Bleher, Bärbel; Brandl, Roland; Dalitz, Helmut; Fischer, Georg; Freund, Wolfram; Gikungu, Mary W.; Hagen, Melanie; Garcia, Francisco Hita; Kagezi, Godfrey H.; Kaib, Manfred; Kraemer, Manfred; Lung, Tobias; Schaab, Gertrud; Templin, Mathias; Uster, Dana; Wägele, J. Wolfgang; Böhning-Gaese, Katrin

    2011-01-01

    Forest fragmentation and selective logging are two main drivers of global environmental change and modify biodiversity and environmental conditions in many tropical forests. The consequences of these changes for the functioning of tropical forest ecosystems have rarely been explored in a comprehensive approach. In a Kenyan rainforest, we studied six animal-mediated ecosystem processes and recorded species richness and community composition of all animal taxa involved in these processes. We used linear models and a formal meta-analysis to test whether forest fragmentation and selective logging affected ecosystem processes and biodiversity and used structural equation models to disentangle direct from biodiversity-related indirect effects of human disturbance on multiple ecosystem processes. Fragmentation increased decomposition and reduced antbird predation, while selective logging consistently increased pollination, seed dispersal and army-ant raiding. Fragmentation modified species richness or community composition of five taxa, whereas selective logging did not affect any component of biodiversity. Changes in the abundance of functionally important species were related to lower predation by antbirds and higher decomposition rates in small forest fragments. The positive effects of selective logging on bee pollination, bird seed dispersal and army-ant raiding were direct, i.e. not related to changes in biodiversity, and were probably due to behavioural changes of these highly mobile animal taxa. We conclude that animal-mediated ecosystem processes respond in distinct ways to different types of human disturbance in Kakamega Forest. Our findings suggest that forest fragmentation affects ecosystem processes indirectly by changes in biodiversity, whereas selective logging influences processes directly by modifying local environmental conditions and resource distributions. The positive to neutral effects of selective logging on ecosystem processes show that the

  12. Geological nature of mineral licks and the reasons for geophagy among animals

    NASA Astrophysics Data System (ADS)

    Panichev, Alexander M.; Popov, Vladimir K.; Chekryzhov, Igor Yu.; Seryodkin, Ivan V.; Sergievich, Alexander A.; Golokhvast, Kirill S.

    2017-06-01

    In this paper, the reasons for geophagy (the eating of rocks by wild herbivores) in two regions of the eastern Sikhote-Alin volcanic belt are considered. The mineralogical and chemical features of the consumed rocks, as well as the geological conditions of their formation, are investigated. A comparative analysis of the mineral and chemical composition of the consumed rocks and the excrement of the animals, almost completely consisting of mineral substances, is carried out. It is established that the consumed rocks are hydrothermally altered rhyolitic tuffs located in the volcanic calderas and early Cenozoic volcano-tectonic depressions. They consist of 30-65 % from zeolites (mainly clinoptilolites) and smectites, possessing powerful sorption properties. According to the obtained data, the main reason for geophagy may be connected with the animals' urge to discard excessive and toxic concentrations of certain elements that are widespread in specific habitats and ingested with forage plants.

  13. Increased incidence of domestic animal bites following a disaster due to natural hazards.

    PubMed

    Warner, G Scott

    2010-01-01

    During deployment following Hurricane Ike in September 2008, bites from domestic animals were among the top three trauma complaints seen at the National Disaster Medical System (NDMS) Disaster Medical Assistance Team (DMAT) base of operations. Unlike previous reports of frightened, misplaced dogs and cats biting strangers and rescue workers, there was an increase in bites associated with presumed non-rabid pets who were known to the bite victim. This was an observational sampling of all patients presenting for medical care during deployment to the AL-3 DMAT base of operations in Webster, Texas, following Hurricane Ike. Findings were compared with unofficial local norms and observations from the literature. Of the people with animal bites presenting to the field hospital, dog bites accounted for 55%, cat bites, 40%, and snake bites, 5%. Most of the wounds required suturing and were not simple punctures. Most bites (70%) involved the hand(s). Some patients presented >24 hours after the bite, and already had developed cellulitis. One patient required transfer and inpatient admission for intravenous antibiotics and debridement of a hand injury with spread into the metacarpophalangeal space. Most of the bites were severe and occurred within the first 72 hours after the hurricane, and waned steadily over the following weeks to baseline levels. No animal bites caused by misplaced dogs and cats biting strangers were seen. There was an increase in bites associated with domesticated pets known to the bite victim. The current NDMS cache is stocked adequately to care for most wounds caused by animal bites. However post-exposure rabies treatment is not part of the routine medications offered. For future disaster preparedness training, pet owners should be aware of the increased potential for dog and cat bites.

  14. Heterogeneous selection at specific loci in natural environments in Arabidopsis thaliana.

    PubMed

    Weinig, Cynthia; Dorn, Lisa A; Kane, Nolan C; German, Zachary M; Halldorsdottir, Solveig S; Ungerer, Mark C; Toyonaga, Yuko; Mackay, Trudy F C; Purugganan, Michael D; Schmitt, Johanna

    2003-09-01

    Genetic variation for quantitative traits is often greater than that expected to be maintained by mutation in the face of purifying natural selection. One possible explanation for this observed variation is the action of heterogeneous natural selection in the wild. Here we report that selection on quantitative trait loci (QTL) for fitness traits in the model plant species Arabidopsis thaliana differs among natural ecological settings and genetic backgrounds. At one QTL, the allele that enhanced the viability of fall-germinating seedlings in North Carolina reduced the fecundity of spring-germinating seedlings in Rhode Island. Several other QTL experienced strong directional selection, but only in one site and seasonal cohort. Thus, different loci were exposed to selection in different natural environments. Selection on allelic variation also depended upon the genetic background. The allelic fitness effects of two QTL reversed direction depending on the genotype at the other locus. Moreover, alternative alleles at each of these loci caused reversals in the allelic fitness effects of a QTL closely linked to TFL1, a candidate developmental gene displaying nucleotide sequence polymorphism consistent with balancing selection. Thus, both environmental heterogeneity and epistatic selection may maintain genetic variation for fitness in wild plant species.

  15. Heterogeneous selection at specific loci in natural environments in Arabidopsis thaliana.

    PubMed Central

    Weinig, Cynthia; Dorn, Lisa A; Kane, Nolan C; German, Zachary M; Halldorsdottir, Solveig S; Ungerer, Mark C; Toyonaga, Yuko; Mackay, Trudy F C; Purugganan, Michael D; Schmitt, Johanna

    2003-01-01

    Genetic variation for quantitative traits is often greater than that expected to be maintained by mutation in the face of purifying natural selection. One possible explanation for this observed variation is the action of heterogeneous natural selection in the wild. Here we report that selection on quantitative trait loci (QTL) for fitness traits in the model plant species Arabidopsis thaliana differs among natural ecological settings and genetic backgrounds. At one QTL, the allele that enhanced the viability of fall-germinating seedlings in North Carolina reduced the fecundity of spring-germinating seedlings in Rhode Island. Several other QTL experienced strong directional selection, but only in one site and seasonal cohort. Thus, different loci were exposed to selection in different natural environments. Selection on allelic variation also depended upon the genetic background. The allelic fitness effects of two QTL reversed direction depending on the genotype at the other locus. Moreover, alternative alleles at each of these loci caused reversals in the allelic fitness effects of a QTL closely linked to TFL1, a candidate developmental gene displaying nucleotide sequence polymorphism consistent with balancing selection. Thus, both environmental heterogeneity and epistatic selection may maintain genetic variation for fitness in wild plant species. PMID:14504239

  16. The Nature of Selection and Judging for the Teacher of the Year Award.

    ERIC Educational Resources Information Center

    McKenna, Bonnie; And Others

    This paper reports on the investigation of the operation of the Teacher of the Year Award program in 28 states. It focuses on the method of selection for recipients of this award, and explores the nature of the judging process used in selecting candidates at both the state and national levels. Specific objectives are: (1) to determine the criteria…

  17. An analysis of phenotypic selection in natural stands of northern red oak (Quercus rubra L.)

    Treesearch

    Jeffery W. Stringer; David B. Wagner; Scott E. Schlarbaum; Daniel B. Houston

    1995-01-01

    Comparison of growth and stem quality parameters of 19-year-old progeny from superior and comparison trees indicates that rigorous phenotypic selection of trees in natural stands may not be an efficient method of parent tree selection for Quercus rubra L. Total tree height, dbh, number of branches in the butt log, fork height, and number of mainstem...

  18. Genetic constraints and the evolution of display trait sexual dimorphism by natural and sexual selection.

    PubMed

    Chenoweth, Stephen F; Rundle, Howard D; Blows, Mark W

    2008-01-01

    The evolution of sexual dimorphism involves an interaction between sex-specific selection and a breakdown of genetic constraints that arise because the two sexes share a genome. We examined genetic constraints and the effect of sex-specific selection on a suite of sexually dimorphic display traits in Drosophila serrata. Sexual dimorphism varied among nine natural populations covering a substantial portion of the species range. Quantitative genetic analyses showed that intersexual genetic correlations were high because of autosomal genetic variance but that the inclusion of X-linked effects reduced genetic correlations substantially, indicating that sex linkage may be an important mechanism by which intersexual genetic constraints are reduced in this species. We then explored the potential for both natural and sexual selection to influence these traits, using a 12-generation laboratory experiment in which we altered the opportunities for each process as flies adapted to a novel environment. Sexual dimorphism evolved, with natural selection reducing sexual dimorphism, whereas sexual selection tended to increase it overall. To this extent, our results are consistent with the hypothesis that sexual selection favors evolutionary divergence of the sexes. However, sex-specific responses to natural and sexual selection contrasted with the classic model because sexual selection affected females rather than males.

  19. Thoughts Toward a Theory of Natural Selection: The Importance of Microbial Experimental Evolution.

    PubMed

    Dykhuizen, Daniel

    2016-01-08

    Natural selection should no longer be thought of simply as a primitive (magical) concept that can be used to support all kinds of evolutionary theorizing. We need to develop causal theories of natural selection; how it arises. Because the factors contributing to the creation of natural selection are expected to be complex and intertwined, theories explaining the causes of natural selection can only be developed through the experimental method. Microbial experimental evolution provides many benefits that using other organisms does not. Microorganisms are small, so millions can be housed in a test tube; they have short generation times, so evolution over hundreds of generations can be easily studied; they can grow in chemically defined media, so the environment can be precisely defined; and they can be frozen, so the fitness of strains or populations can be directly compared across time. Microbial evolution experiments can be divided into two types. The first is to measure the selection coefficient of two known strains over the first 50 or so generations, before advantageous mutations rise to high frequency. This type of experiment can be used to directly test hypotheses. The second is to allow microbial cultures to evolve over many hundreds or thousands of generations and follow the genetic changes, to infer what phenotypes are selected. In the last section of this article, I propose that selection coefficients are not constant, but change as the population becomes fitter, introducing the idea of the selection space.

  20. The basic science and mathematics of random mutation and natural selection.

    PubMed

    Kleinman, Alan

    2014-12-20

    The mutation and natural selection phenomenon can and often does cause the failure of antimicrobial, herbicidal, pesticide and cancer treatments selection pressures. This phenomenon operates in a mathematically predictable behavior, which when understood leads to approaches to reduce and prevent the failure of the use of these selection pressures. The mathematical behavior of mutation and selection is derived using the principles given by probability theory. The derivation of the equations describing the mutation and selection phenomenon is carried out in the context of an empirical example. Copyright © 2014 John Wiley & Sons, Ltd.

  1. Index of opportunity for natural selection among the Gowdas of Kodagahalli village, Karnataka, India.

    PubMed

    Sohkhlet, Bhaboklang

    2013-07-01

    In order to understand how selection is operating in the Gowda population, the index of opportunity for selection was calculated and the present findings were compared with some related findings from other South Indian (SI) populations. Crow (1958) and the modified method by Johnston and Kensinger (1971) were used for the present purpose. The index of total selection intensity (I) was found to be moderate taking into consideration the range for many Indian populations. Considering certain differences in fertility and mortality heritable, it appears that natural selection play an important role in shaping the genetic constitution of the Gowda population. Analysis of data indicates that the index due to fertility seems to contribute more towards selection than mortality. This trend might be because of better living condition and health-care system among the Gowdas which have a positive impact on the lower contribution of mortality for the evolution mechanism of the Gowda population through natural selection.

  2. Emergence of life: from functional RNA selection to natural selection and beyond.

    PubMed

    Wong, Jeffrey Tze-Fei

    2014-06-01

    This study tracks the rise, evolution and post-evolution of the genetic information system through emergence of life. The major stages traversed include prebiotic synthesis, functional RNA selection by metabolite, RNA World, peptidated RNA world, co-evolution of genetic code and amino acid biosynthesis, last universal common ancestor, Darwinian evolution and synthetic life.

  3. Response to selection under controlled environment versus natural selection in diverse regions across Canada

    USDA-ARS?s Scientific Manuscript database

    Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

  4. Natural Selection

    ERIC Educational Resources Information Center

    Hall, Julie

    2006-01-01

    For education administrators, summer break is the time to regroup and prepare facilities for the next influx of students. Ensuring that facilities are equipped with proper furnishings is part of this preparation. Through careful research and planning, education administrators can choose furniture that will become a lasting investment. This article…

  5. The paradoxical advantages and disadvantages of natural selection: the case history of Charles Darwin.

    PubMed

    Lieb, J

    2007-01-01

    The biology of natural selection is an enduring mystery, as is the nature of Charles Darwin's chronic illness. Of the theories advanced to explain the latter, Oedipal conflicts and Chagas' disease are preeminent. Hypomania, however, propelled Darwin to the pinnacle of scientific achievement and good health, the depression that followed condemning him to intellectual stagnation, lethargy, impaired memory and concentration, and incapacitating gastrointestinal disorders. Examples of natural selection in humans are much sought after when, ironically, one need look no further than Darwin himself.

  6. Select agent and toxin regulations: beyond the eighth edition of the Guide for the Care and Use of Laboratory Animals.

    PubMed

    Kastenmayer, Robin J; Moore, Rashida M; Bright, Allison L; Torres-Cruz, Rafael; Elkins, William R

    2012-05-01

    In the interval between the publication of the seventh and eighth editions of the Guide for the Care and Use of Laboratory Animals (Guide), much has changed with regard to the regulation and funding of highly pathogenic biologic agents and toxins (Select Agents). Funding of research involving highly pathogenic agents has increased dramatically during this time, thus increasing the demand for facilities capable of supporting this work. The eighth edition of the Guide briefly mentions Select Agents and provides a limited set of references. Here we provide some background information regarding the relevant laws and regulations, as well as an overview of the programmatic requirements pertaining to the use of Select Agents, with a focus on use in animals.

  7. Select Agent and Toxin Regulations: Beyond the Eighth Edition of the Guide for the Care and Use of Laboratory Animals

    PubMed Central

    Kastenmayer, Robin J; Moore, Rashida M; Bright, Allison L; Torres-Cruz, Rafael; Elkins, William R

    2012-01-01

    In the interval between the publication of the seventh and eighth editions of the Guide for the Care and Use of Laboratory Animals (Guide), much has changed with regard to the regulation and funding of highly pathogenic biologic agents and toxins (Select Agents). Funding of research involving highly pathogenic agents has increased dramatically during this time, thus increasing the demand for facilities capable of supporting this work. The eighth edition of the Guide briefly mentions Select Agents and provides a limited set of references. Here we provide some background information regarding the relevant laws and regulations, as well as an overview of the programmatic requirements pertaining to the use of Select Agents, with a focus on use in animals. PMID:22776191

  8. Estimating selection through male fitness: three complementary methods illuminate the nature and causes of selection on flowering time.

    PubMed

    Austen, Emily J; Weis, Arthur E

    2016-02-24

    Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution. Selection differentials estimated by the first method disagreed with those estimated by the other two, indicating that mating opportunity was not the principal driver of selection on flowering time. The genetic and experimental evolution methods exhibited striking agreement overall, but a slight discrepancy between the two suggested that negative environmental covariance between age at flowering and male fitness may have contributed to phenotypic selection. Together, the three methods enriched our understanding of selection on flowering time, from mating opportunity to phenotypic selection to evolutionary response. The novel experimental evolution method may provide a means of examining selection through male fitness when genetic paternity analysis is not possible.

  9. Estimating selection through male fitness: three complementary methods illuminate the nature and causes of selection on flowering time

    PubMed Central

    Austen, Emily J.; Weis, Arthur E.

    2016-01-01

    Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution. Selection differentials estimated by the first method disagreed with those estimated by the other two, indicating that mating opportunity was not the principal driver of selection on flowering time. The genetic and experimental evolution methods exhibited striking agreement overall, but a slight discrepancy between the two suggested that negative environmental covariance between age at flowering and male fitness may have contributed to phenotypic selection. Together, the three methods enriched our understanding of selection on flowering time, from mating opportunity to phenotypic selection to evolutionary response. The novel experimental evolution method may provide a means of examining selection through male fitness when genetic paternity analysis is not possible. PMID:26911957

  10. New directions for studying selection in nature: studies of performance and communities.

    PubMed

    Irschick, Duncan; Bailey, Joseph K; Schweitzer, Jennifer A; Husak, Jerry F; Meyers, Jerry J

    2007-01-01

    Natural and sexual selection are crucial factors in the evolutionary process, yet recent reviews show that researchers have focused narrowly on this topic, with the majority of research centered on the morphological traits of single species. However, in the past several years, several bodies of work have emerged that have examined both selection on performance capacity and selection in a community context, and our goal is to highlight these two growing areas and point toward future directions. Recent studies of selection on performance capacity point toward directional selection favoring high levels of performance, and we detected less evidence for selection favoring intermediate (i.e., stabilizing) or bimodal (i.e., disruptive) kinds of performance levels. Studies of selection in a community context, using the paradigm of indirect genetic effects, show significant community heritability and strong capacity for evolution to occur in a community context via the force of natural selection. For future directions, we argue that researchers should shift toward longer-term studies of selection on both individual species and communities, and we also encourage researchers to publish negative selection results for both performance and community studies to act as balancing influences on published positive selection results.

  11. Understanding Cellular Mechanisms Underlying Airway Epithelial Repair: Selecting the Most Appropriate Animal Models

    PubMed Central

    Yahaya, B.

    2012-01-01

    Understanding the mechanisms underlying the process of regeneration and repair of airway epithelial structures demands close characterization of the associated cellular and molecular events. The choice of an animal model system to study these processes and the role of lung stem cells is debatable since ideally the chosen animal model should offer a valid comparison with the human lung. Species differences may include the complex three-dimensional lung structures, cellular composition of the lung airway as well as transcriptional control of the molecular events in response to airway epithelium regeneration, and repair following injury. In this paper, we discuss issues related to the study of the lung repair and regeneration including the role of putative stem cells in small- and large-animal models. At the end of this paper, the author discuss the potential for using sheep as a model which can help bridge the gap between small-animal model systems and humans. PMID:23049478

  12. Modifying effects of phenotypic plasticity on interactions among natural selection, adaptation and gene flow.

    PubMed

    Crispo, E

    2008-11-01

    Divergent natural selection, adaptive divergence and gene flow may interact in a number of ways. Recent studies have focused on the balance between selection and gene flow in natural populations, and empirical work has shown that gene flow can constrain adaptive divergence, and that divergent selection can constrain gene flow. A caveat is that phenotypic diversification may be under the direct influence of environmental factors (i.e. it may be due to phenotypic plasticity), in addition to partial genetic influence. In this case, phenotypic divergence may occur between populations despite high gene flow that imposes a constraint on genetic divergence. Plasticity may dampen the effects of natural selection by allowing individuals to rapidly adapt phenotypically to new conditions, thus slowing adaptive genetic divergence. On the other hand, plasticity may promote future adaptive divergence by allowing populations to persist in novel environments. Plasticity may promote gene flow between selective regimes by allowing dispersers to adapt to alternate conditions, or high gene flow may result in the selection for increased plasticity. Here I expand frameworks for understanding relationships among selection, adaptation and gene flow to include the effects of phenotypic plasticity in natural populations, and highlight its importance in evolutionary diversification.

  13. Natural selection affects multiple aspects of genetic variation at putatively neutral sites across the human genome.

    PubMed

    Lohmueller, Kirk E; Albrechtsen, Anders; Li, Yingrui; Kim, Su Yeon; Korneliussen, Thorfinn; Vinckenbosch, Nicolas; Tian, Geng; Huerta-Sanchez, Emilia; Feder, Alison F; Grarup, Niels; Jørgensen, Torben; Jiang, Tao; Witte, Daniel R; Sandbæk, Annelli; Hellmann, Ines; Lauritzen, Torsten; Hansen, Torben; Pedersen, Oluf; Wang, Jun; Nielsen, Rasmus

    2011-10-01

    A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries of genetic variation, like allele frequencies, are also correlated with recombination rate and whether these correlations can be explained solely by negative selection against deleterious mutations or whether positive selection acting on favorable alleles is also required. Here we attempt to address these questions by analyzing three different genome-wide resequencing datasets from European individuals. We document several significant correlations between different genomic features. In particular, we find that average minor allele frequency and diversity are reduced in regions of low recombination and that human diversity, human-chimp divergence, and average minor allele frequency are reduced near genes. Population genetic simulations show that either positive natural selection acting on favorable mutations or negative natural selection acting against deleterious mutations can explain these correlations. However, models with strong positive selection on nonsynonymous mutations and little negative selection predict a stronger negative correlation between neutral diversity and nonsynonymous divergence than observed in the actual data, supporting the importance of negative, rather than positive, selection throughout the genome. Further, we show that the widespread presence of weakly deleterious alleles, rather than a small number of strongly positively selected mutations, is responsible for the correlation between neutral genetic diversity and recombination rate. This work suggests that natural selection has affected multiple aspects of linked neutral variation throughout the human genome and that positive selection is not required to explain these observations.

  14. Natural Selection Affects Multiple Aspects of Genetic Variation at Putatively Neutral Sites across the Human Genome

    PubMed Central

    Lohmueller, Kirk E.; Albrechtsen, Anders; Li, Yingrui; Kim, Su Yeon; Korneliussen, Thorfinn; Vinckenbosch, Nicolas; Tian, Geng; Huerta-Sanchez, Emilia; Feder, Alison F.; Grarup, Niels; Jørgensen, Torben; Jiang, Tao; Witte, Daniel R.; Sandbæk, Annelli; Hellmann, Ines; Lauritzen, Torsten; Hansen, Torben

    2011-01-01

    A major question in evolutionary biology is how natural selection has shaped patterns of genetic variation across the human genome. Previous work has documented a reduction in genetic diversity in regions of the genome with low recombination rates. However, it is unclear whether other summaries of genetic variation, like allele frequencies, are also correlated with recombination rate and whether these correlations can be explained solely by negative selection against deleterious mutations or whether positive selection acting on favorable alleles is also required. Here we attempt to address these questions by analyzing three different genome-wide resequencing datasets from European individuals. We document several significant correlations between different genomic features. In particular, we find that average minor allele frequency and diversity are reduced in regions of low recombination and that human diversity, human-chimp divergence, and average minor allele frequency are reduced near genes. Population genetic simulations show that either positive natural selection acting on favorable mutations or negative natural selection acting against deleterious mutations can explain these correlations. However, models with strong positive selection on nonsynonymous mutations and little negative selection predict a stronger negative correlation between neutral diversity and nonsynonymous divergence than observed in the actual data, supporting the importance of negative, rather than positive, selection throughout the genome. Further, we show that the widespread presence of weakly deleterious alleles, rather than a small number of strongly positively selected mutations, is responsible for the correlation between neutral genetic diversity and recombination rate. This work suggests th