Role of Overlapping Generations in Maintaining Genetic Variation in a Fluctuating Environment
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Evolution of Amphimixis and Recombination Under Fluctuating Selection in One and Many Traits
Genet. Res., Camb. (1996), 68, pp. 165-173 With 7 text-figures Copyright © 1996 Cambridge University Press 165 Evolution of amphimixis and recombination under fluctuating selection in one and many traits ALEXEY S. KONDRASHOV* AND LEV YU. YAMPOLSKY Section of Ecology and Systematics, Cornell University, Ithaca, NY 14853, USA (Received 6 June 1995 and in revised form 14 May 1996) Summary Both stabilizing and directional selection acting on one or many quantitative traits usually reduce the genetic variance in a polymorphic population. Amphimixis and recombination restore the variance, pushing it closer to its value under linkage equilibrium. They thus increase the response of the population to fluctuating selection and decrease the genetic load when the mean phenotype is far from optimum. Amphimixis can have a short-term advantage over apomixis if selection fluctuates frequently and widely, so that every genotype often has a low fitness. Such selection causes high genetic variance due to frequent allele substitutions, and a high load even with amphimixis. Recombination in an amphimictic population is maintained only if selection is usually strong and effectively directional. A modifier allele causing free recombination can have a significant advantage only if fluctuations of selection are such that the load is substantial. With smaller fluctuations, an intermediate recombination rate can be established, either due to fixation of alleles that cause such a rate or due to the stable coexistence of alleles causing high and low recombination. If many traits simultaneously are under fluctuating selection, amphimixis and recombination can be maintained when selection associated with individual traits is weaker and the changes in their mean values are smaller than with a single trait. -
Effective Population Size and Genetic Conservation Criteria for Bull Trout
North American Journal of Fisheries Management 21:756±764, 2001 q Copyright by the American Fisheries Society 2001 Effective Population Size and Genetic Conservation Criteria for Bull Trout B. E. RIEMAN* U.S. Department of Agriculture Forest Service, Rocky Mountain Research Station, 316 East Myrtle, Boise, Idaho 83702, USA F. W. A LLENDORF Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA Abstract.ÐEffective population size (Ne) is an important concept in the management of threatened species like bull trout Salvelinus con¯uentus. General guidelines suggest that effective population sizes of 50 or 500 are essential to minimize inbreeding effects or maintain adaptive genetic variation, respectively. Although Ne strongly depends on census population size, it also depends on demographic and life history characteristics that complicate any estimates. This is an especially dif®cult problem for species like bull trout, which have overlapping generations; biologists may monitor annual population number but lack more detailed information on demographic population structure or life history. We used a generalized, age-structured simulation model to relate Ne to adult numbers under a range of life histories and other conditions characteristic of bull trout populations. Effective population size varied strongly with the effects of the demographic and environmental variation included in our simulations. Our most realistic estimates of Ne were between about 0.5 and 1.0 times the mean number of adults spawning annually. We conclude that cautious long-term management goals for bull trout populations should include an average of at least 1,000 adults spawning each year. Where local populations are too small, managers should seek to conserve a collection of interconnected populations that is at least large enough in total to meet this minimum. -
Negative Frequency-Dependent Selection Is Frequently Confounding
PERSPECTIVE published: 21 February 2018 doi: 10.3389/fevo.2018.00010 Negative Frequency-Dependent Selection Is Frequently Confounding Dustin Brisson* Biology Department, University of Pennsylvania, Philadelphia, PA, United States Persistent genetic variation within populations presents an evolutionary problem, as natural selection and genetic drift tend to erode genetic diversity. Models of balancing selection were developed to account for the maintenance of genetic variation observed in natural populations. Negative frequency-dependent selection is a powerful type of balancing selection that maintains many natural polymorphisms, but it is also commonly misinterpreted. This review aims to clarify the processes underlying negative frequency-dependent selection, describe classes of polymorphisms that can and cannot result from these processes, and discuss the empirical data needed to accurately identify processes that generate or maintain diversity in nature. Finally, the importance of accurately describing the processes affecting genetic diversity within populations as it relates to research progress is considered. Keywords: negative frequency dependent selection, balancing selection, killing the winner hypothesis, multiple niche polymorphism, density dependent selection Edited by: Norman A. Johnson, University of Massachusetts Amherst, United States INTRODUCTION Reviewed by: Natural diversity—the “endless forms most beautiful and most wonderful” (Darwin, 2012)— Rama Shankar Singh, Is an enduring focus of both evolutionary biologists and -
Host–Parasite Fluctuating Selection in the Absence of Specificity
Heriot-Watt University Research Gateway Host–parasite fluctuating selection in the absence of specificity Citation for published version: Best, A, Ashby, B, White, A, Bowers, R, Buckling, A, Koskella, B & Boots, M 2017, 'Host–parasite fluctuating selection in the absence of specificity', Proceedings of the Royal Society B: Biological Sciences, vol. 284, no. 1866, 20171615. https://doi.org/10.1098/rspb.2017.1615 Digital Object Identifier (DOI): 10.1098/rspb.2017.1615 Link: Link to publication record in Heriot-Watt Research Portal Document Version: Publisher's PDF, also known as Version of record Published In: Proceedings of the Royal Society B: Biological Sciences General rights Copyright for the publications made accessible via Heriot-Watt Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy Heriot-Watt University has made every reasonable effort to ensure that the content in Heriot-Watt Research Portal complies with UK legislation. If you believe that the public display of this file breaches copyright please contact [email protected] providing details, and we will remove access to the work immediately and investigate your claim. Download date: 25. Sep. 2021 Downloaded from http://rspb.royalsocietypublishing.org/ on March 5, 2018 Host–parasite fluctuating selection in the rspb.royalsocietypublishing.org absence of specificity Alex Best1, Ben Ashby2,3, Andy White4, Roger Bowers5, Angus Buckling6, Britt Koskella3 and Mike Boots3,6 Research 1School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK 2Department of Mathematical Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK Cite this article: Best A, Ashby B, White A, 3Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA 4 Bowers R, Buckling A, Koskella B, Boots M. -
Recent Selection Changes in Human Genes Under Long-Term Balancing Selection Cesare De Filippo,*,1 Felix M
MBE Advance Access published March 10, 2016 Recent Selection Changes in Human Genes under Long-Term Balancing Selection Cesare de Filippo,*,1 Felix M. Key,1 Silvia Ghirotto,2 Andrea Benazzo,2 Juan R. Meneu,1 Antje Weihmann,1 NISC Comparative Sequence Program,3 Genı´s Parra,1 Eric D. Green,3 and Aida M. Andre´s*,1 1Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany 2Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy 3National Human Genome Research Institute, National Institutes of Health, Bethesda, MD *Corresponding author: E-mail: cesare_fi[email protected]; [email protected]. Associate editor: Ryan Hernandez Abstract Balancing selection is an important evolutionary force that maintains genetic and phenotypic diversity in populations. Most studies in humans have focused on long-standing balancing selection, which persists over long periods of time and is generally shared across populations. But balanced polymorphisms can also promote fast adaptation, especially when the Downloaded from environment changes. To better understand the role of previously balanced alleles in novel adaptations, we analyzed in detail four loci as case examples of this mechanism. These loci show hallmark signatures of long-term balancing selection in African populations, but not in Eurasian populations. The disparity between populations is due to changes in allele frequencies, with intermediate frequency alleles in Africans (likely due to balancing selection) segregating instead at low- or high-derived allele frequency in Eurasia. We explicitly tested the support for different evolutionary models with an http://mbe.oxfordjournals.org/ approximate Bayesian computation approach and show that the patterns in PKDREJ, SDR39U1,andZNF473 are best explained by recent changes in selective pressure in certain populations. -
Multi-Mode Fluctuating Selection in Host-Parasite Coevolution
ORE Open Research Exeter TITLE Multi-mode fluctuating selection in host-parasite coevolution. AUTHORS Ashby, B; Boots, M JOURNAL Ecology Letters DEPOSITED IN ORE 15 February 2017 This version available at http://hdl.handle.net/10871/25858 COPYRIGHT AND REUSE Open Research Exeter makes this work available in accordance with publisher policies. A NOTE ON VERSIONS The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication Multi-mode fluctuating selection in host-parasite coevolution Ben Ashbya,b* and Mike Bootsb,c a. Department of Mathematical Sciences, University of Bath, Bath BA2 7AY, UK b. Integrative Biology, University of California Berkeley, Berkeley, CA, USA c. Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9EZ, UK *Corresponding author: [email protected] Statement of Authorship: BA & MB conceived the study and wrote the manuscript. BA analysed the theoretical model. This is the peer reviewed version of the following article: Ashby, B. and Boots, M. 2017 Multi-mode fluctuating selection in host-parasite coevolution. Ecol. Lett., which has been published in final form at http://onlinelibrary.wiley.com/wol1/doi/10.1111/ele.12734/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self- Archiving. Ashby, B. and Boots, M. 2017 Multi-mode fluctuating selection in host-parasite coevolution. Ecol. Lett. Understanding fluctuating selection is important for our understanding of patterns of spatial and temporal diversity in nature. Host-parasite theory has classically assumed fluctuations either occur between highly specific genotypes (Matching Alleles: MA) or from specialism to generalism (Gene- for-Gene: GFG). -
It's About Time: the Temporal Dynamics of Phenotypic Selection in the Wild
Ecology Letters, (2009) 12: 1261–1276 doi: 10.1111/j.1461-0248.2009.01381.x REVIEW AND SYNTHESIS ItÕs about time: the temporal dynamics of phenotypic selection in the wild Abstract Adam M. Siepielski,1* Joseph Selection is a central process in nature. Although our understanding of the strength and D. DiBattista2 and Stephanie form of selection has increased, a general understanding of the temporal dynamics of M. Carlson3 selection in nature is lacking. Here, we assembled a database of temporal replicates of 1 Department of Biological selection from studies of wild populations to synthesize what we do (and do not) know Sciences, Dartmouth College, about the temporal dynamics of selection. Our database contains 5519 estimates of Hanover, NH 03755, USA selection from 89 studies, including estimates of both direct and indirect selection as well 2Redpath Museum and as linear and nonlinear selection. Morphological traits and studies focused on vertebrates Department of Biology, McGill were well-represented, with other traits and taxonomic groups less well-represented. University, Montre´ al, QC H3A 2K6, Canada Overall, three major features characterize the temporal dynamics of selection. First, the 3University of California, strength of selection often varies considerably from year to year, although random Department of Environmental sampling error of selection coefficients may impose bias in estimates of the magnitude of Science, Policy, and such variation. Second, changes in the direction of selection are frequent. Third, changes Management, 137 Mulford Hall in the form of selection are likely common, but harder to quantify. Although few studies 3114, Berkeley, CA 94720, USA have identified causal mechanisms underlying temporal variation in the strength, *Correspondence: E-mail: direction and form of selection, variation in environmental conditions driven by climatic Adam.M.Siepielski@Dartmouth. -
A Genome-Wide Scan for Genes Under Balancing Selection in Drosophila Melanogaster
A genome-wide scan for genes under balancing selection in Drosophila melanogaster Dissertation an der Fakultät für Biologie der Ludwig-Maximilians-Universität München vorgelegt von Myriam Florence Croze aus Montélimar München, Januar 2017 1. Gutachter: Prof. Wolfgang Stephan 2. Gutachter: Prof. John Parsch Tag der Einreichung: 17.01.2017 Tag der mündlichen Prüfung: 13.03.2017 1 2 Erklärung: Diese Dissertation wurde im Sinne von §12 der Promotionsordnung von Prof. Dr. Stephan betreut. Ich erkläre hiermit, dass die Dissertation nicht ganz oder in wesentlichen Teilen einer anderen Prüfungskommission vorgelegt worden ist und dass ich mich nicht anderweitig einer Doktorprüfung ohne Erfolg unterzogen habe. Eidesstattliche Erklärung: Ich versichere hiermit an Eides statt, dass die vorgelegte Dissertation von mir selbstständig und ohne unerlaubte Hilfe angefertigt ist. München, den 17.01.2017 Myriam Croze 3 4 Table of contents Note .................................................................................................................................................. 7 List of abbreviations ......................................................................................................................... 9 List of figures ................................................................................................................................. 10 List of tables ................................................................................................................................... 11 CHAPTER 1: INTRODUCTION ................................................................................................. -
A Mathematical Model of the Evolution of Individual Differences in Developmental Plasticity Arising Through Parental Bet-Hedging
UC Davis UC Davis Previously Published Works Title A mathematical model of the evolution of individual differences in developmental plasticity arising through parental bet-hedging. Permalink https://escholarship.org/uc/item/4bh108gv Journal Developmental science, 19(2) ISSN 1363-755X Authors Frankenhuis, Willem E Panchanathan, Karthik Belsky, Jay Publication Date 2016-03-01 DOI 10.1111/desc.12309 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Developmental Science 19:2 (2016), pp 251–274 DOI: 10.1111/desc.12309 PAPER A mathematical model of the evolution of individual differences in developmental plasticity arising through parental bet-hedging Willem E. Frankenhuis,1 Karthik Panchanathan2 and Jay Belsky3 1. Behavioural Science Institute, Radboud University Nijmegen, The Netherlands 2. Department of Anthropology, University of Missouri, USA 3. Human Ecology, University of California, Davis, USA Abstract Children vary in the extent to which their development is shaped by particular experiences (e.g. maltreatment, social support). This variation raises a question: Is there no single level of plasticity that maximizes biological fitness? One influential hypothesis states that when different levels of plasticity are optimal in different environmental states and the environment fluctuates unpredictably, natural selection may favor parents producing offspring with varyinglevels of plasticity. The current article presents a mathematical model assessing the logic of this hypothesis – specifically, it examines what conditions are required for natural selection to favor parents to bet-hedge by varying their offspring’s plasticity. Consistent with existing theory from biology, results show that between- individual variation in plasticity cannot evolve when the environment only varies across space. -
Experimental Evolution of Chlamydomonas Reinhardtii Under Salt Stress
Experimental evolution of Chlamydomonas reinhardtii under salt stress Chase Curtis Moser Department of Biology McGill University, Montreal June 2010 A thesis submitted to McGill University in partial fulfilment of the requirements of the degree of Master of Science. © Chase Moser 2010 Library and Archives Bibliothèque et Canada Archives Canada Published Heritage Direction du Branch Patrimoine de l’édition 395 Wellington Street 395, rue Wellington Ottawa ON K1A 0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre référence ISBN: 978-0-494-72799-7 Our file Notre référence ISBN: 978-0-494-72799-7 NOTICE: AVIS: The author has granted a non- L’auteur a accordé une licence non exclusive exclusive license allowing Library and permettant à la Bibliothèque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par télécommunication ou par l’Internet, prêter, telecommunication or on the Internet, distribuer et vendre des thèses partout dans le loan, distribute and sell theses monde, à des fins commerciales ou autres, sur worldwide, for commercial or non- support microforme, papier, électronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L’auteur conserve la propriété du droit d’auteur ownership and moral rights in this et des droits moraux qui protège cette thèse. Ni thesis. Neither the thesis nor la thèse ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent être imprimés ou autrement printed or otherwise reproduced reproduits sans son autorisation. -
Memes of Haldane and Jayakar in a Theory of Sex
J. Genet. Vol. 69, No. 1, April 1990, pp. 17-32. 9 Printed in India. Memes of Haldane and Jayakar in a theory of sex W. D. HAMILTON Department of Zoology, South Parks Road, Oxford OX1 3PS, U.K. Abstract, The history of mathematical modelling of communities and polymorphisms under intrinsic fluctuating selection is outlined. Authors have usually encountered difficulty in obtaining stability in cases involving host-parasite relations. Stability may in fact be uncommon. On the other hand protection of diversity (non-extinction of rare species or variants) may instead be common and important. Within multilocus systems, mild truncation selection on a host-parasite system both protects variation and is supportative of sexuality against parthenogenesis even when sex pays a full cost-that is, even if sex has halved the efficiency of reproduction due to production of males. Truncation based on heritable health, which is itself based on polygenic resistance to parasites, provides the most robust and universal model supporting sex yet presented. The separate and joint roles of J. B. S. Haldane and S. D. Jayakar in originating ideas now incorporated in the model are discussed. Keywords. Cycles; protected polymorphism; parasites; multilocus genetics; truncation; sex. Introduction For the past ten years I have developed an idea that the ultimate evolutionary cause of sex is disease. The idea is increasingly credible. This is not so much because favourable evidence is accumulating, although the scraps that come to light from time to time, usually having been published incidental to some other objective, are mostly favourable. It is rather the model itself, its engineering and appropriateness for its task, that has improved. -
Effects of Overlapping Generations on Linkage Disequilibrium Estimates of Effective Population Size
INVESTIGATION Effects of Overlapping Generations on Linkage Disequilibrium Estimates of Effective Population Size Robin S. Waples,*,1 Tiago Antao,† and Gordon Luikart‡ *Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington 98112, †Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA United Kingdom, and ‡Flathead Lake Biological Station, Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Polson, Montana 59860 ABSTRACT Use of single-sample genetic methods to estimate effective population size has skyrocketed in recent years. Although the underlying models assume discrete generations, they are widely applied to age-structured species. We simulated genetic data for 21 iteroparous animal and plant species to evaluate two untested hypotheses regarding performance of the single-sample method based on linkage disequilibrium (LD): (1) estimates based on single-cohort samples reflect the effective number of breeders in one reproductive cycle (Nb), and (2) mixed-age samples reflect the effective size per generation (Ne). We calculated true Ne and Nb, using the model species’ vital rates, and verified these with individual-based simulations. We show that single-cohort samples should be ^ 2 equally influenced by Nb and Ne and confirm this with simulated results: Nb was a linear (r = 0.98) function of the harmonic mean of ^ Ne and Nb. We provide a quantitative bias correction for raw Nb based on the ratio Nb/Ne, which can be estimated from two or three simple life history traits. Bias-adjusted estimates were within 5% of true Nb for all 21 study species and proved robust when challenged with new data.