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Zhou A, Ding Y, Zhang X, Zhou Y, Liu Y, Li T, Xiao L. Whole-genome resequencing reveals new mutations in candidate genes for Beichuan-white goat prolificacya. Anim Biotechnol 2024; 35:2258166. [PMID: 37729465 DOI: 10.1080/10495398.2023.2258166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
In this study, we evaluated the copy number variation in the genomes of two groups of Beichuan-white goat populations with large differences in litter size by FST method, and identified 1739 genes and 485 missense mutations in the genes subject to positive selection. Through functional enrichment, ITGAV, LRP4, CDH23, TPRN, RYR2 and CELSR1 genes, involved in embryonic morphogenesis, were essential for litter size trait, which received intensive attention. In addition, some mutation sites of these genes have been proposed (ITGAV: c.38C > T; TPRN: c.133A > T, c.1192A > G, c.1250A > C; CELSR1: c.7640T > C), whose allele frequencies were significantly changed in the high fecundity goat group. Besides, we found that new mutations at these sites altered the hydrophilicity and 3D structure of the protein. Candidate genes related to litter size in this study and their missense mutation sites were identified. These candidate genes are helpful to understand the genetic mechanism of fecundity in Beichuan white goat, and have important significance for future goat breeding.
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Affiliation(s)
- Aimin Zhou
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, P. R. China
| | - Yi Ding
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, P. R. China
| | - Xiaohui Zhang
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
| | - Yugang Zhou
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
| | - Yadong Liu
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
| | - Tingjian Li
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
| | - Long Xiao
- Animal Husbandry Research Institute, Mianyang Academy of Agricultural Sciences, Mianyang, P. R. China
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2
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Ansari S, Ghavi Hossein-Zadeh N, Shadparvar AA. Genomic predictions under different genetic architectures are impacted by mating designs. Vet Anim Sci 2024; 25:100373. [PMID: 39036417 PMCID: PMC11260037 DOI: 10.1016/j.vas.2024.100373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024] Open
Abstract
Mating in animal communities must be managed in a way that assures the performance increase in the progenies without increasing the rate of inbreeding. It has currently become possible to identify millions of single nucleotide polymorphisms (SNPs), and it is feasible to select animals based on genome-wide marker profiles. This study aimed to evaluate the impact of five mating designs among individuals (random, positive and negative assortative, minimized and maximized inbreeding) on genomic prediction accuracy. The choice of these five particular mating designs provides a thorough analysis of the way genetic diversity, relatedness, inbreeding, and biological conditions influence the accuracy of genomic predictions. Utilizing a stochastic simulation technique, various marker and quantitative trait loci (QTL) densities were taken into account. The heritabilities of a simulated trait were 0.05, 0.30, and 0.60. A validation population that only had genotypic records was taken into consideration, and a reference population that had both genotypic and phenotypic records was considered for every simulation scenario. By measuring the correlation between estimated and true breeding values, the prediction accuracy was calculated. Computing the regression of true genomic breeding value on estimated genomic breeding value allowed for the examination of prediction bias. The scenario with a positive assortative mating design had the highest accuracy of genomic prediction (0.733 ± 0.003 to 0.966 ± 0.001). In a case of negative assortative mating, the genomic evaluation's accuracy was lowest (0.680 ± 0.011 to 0.899 ± 0.003). Applying the positive assortative mating design resulted in the unbiased regression coefficients of true genomic breeding value on estimated genomic breeding value. Based on the current results, it is suggested to implement positive assortative mating in genomic evaluation programs to obtain unbiased genomic predictions with greater accuracy. This study implies that animal breeding programs can improve offspring performance without compromising genetic health by carefully managing mating strategies based on genetic diversity, relatedness, and inbreeding levels. To maximize breeding results and ensure long-term genetic improvement in animal populations, this study highlights the importance of considering different mating designs when evaluating genomic information. When incorporating positive assortative mating or other mating schemes into genomic evaluation programs, it is critical to consider the complex relationship between gene interactions, environmental influences, and genetic drift to ensure the stability and effectiveness of breeding efforts. Further research and comprehensive analyzes are needed to fully understand the impact of these factors and their possible complex interactions on the accuracy of genomic prediction and to develop strategies that optimize breeding outcomes in animal populations.
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Affiliation(s)
- Sahar Ansari
- Department of Animal Science, Faculty of Agricultural Sciences, University of Guilan, Rasht, 41635-1314, Iran
| | - Navid Ghavi Hossein-Zadeh
- Department of Animal Science, Faculty of Agricultural Sciences, University of Guilan, Rasht, 41635-1314, Iran
| | - Abdol Ahad Shadparvar
- Department of Animal Science, Faculty of Agricultural Sciences, University of Guilan, Rasht, 41635-1314, Iran
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3
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Bitter MC, Berardi S, Oken H, Huynh A, Lappo E, Schmidt P, Petrov DA. Continuously fluctuating selection reveals fine granularity of adaptation. Nature 2024:10.1038/s41586-024-07834-x. [PMID: 39143223 DOI: 10.1038/s41586-024-07834-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 07/16/2024] [Indexed: 08/16/2024]
Abstract
Temporally fluctuating environmental conditions are a ubiquitous feature of natural habitats. Yet, how finely natural populations adaptively track fluctuating selection pressures via shifts in standing genetic variation is unknown1,2. Here we generated genome-wide allele frequency data every 1-2 generations from a genetically diverse population of Drosophila melanogaster in extensively replicated field mesocosms from late June to mid-December (a period of approximately 12 total generations). Adaptation throughout the fundamental ecological phases of population expansion, peak density and collapse was underpinned by extremely rapid, parallel changes in genomic variation across replicates. Yet, the dominant direction of selection fluctuated repeatedly, even within each of these ecological phases. Comparing patterns of change in allele frequency to an independent dataset procured from the same experimental system demonstrated that the targets of selection are predictable across years. In concert, our results reveal a fitness relevance of standing variation that is likely to be masked by inference approaches based on static population sampling or insufficiently resolved time-series data. We propose that such fine-scaled, temporally fluctuating selection may be an important force contributing to the maintenance of functional genetic variation in natural populations and an important stochastic force impacting genome-wide patterns of diversity at linked neutral sites, akin to genetic draft.
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Affiliation(s)
- M C Bitter
- Department of Biology, Stanford University, Stanford, CA, USA.
| | - S Berardi
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - H Oken
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - A Huynh
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Egor Lappo
- Department of Biology, Stanford University, Stanford, CA, USA
| | - P Schmidt
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
| | - D A Petrov
- Department of Biology, Stanford University, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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4
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Ascensao JA, Lok K, Hallatschek O. Asynchronous abundance fluctuations can drive giant genotype frequency fluctuations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.23.581776. [PMID: 38562700 PMCID: PMC10983864 DOI: 10.1101/2024.02.23.581776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Large stochastic population abundance fluctuations are ubiquitous across the tree of life1-7, impacting the predictability of population dynamics and influencing eco-evolutionary outcomes. It has generally been thought that these large abundance fluctuations do not strongly impact evolution, as the relative frequencies of alleles in the population will be unaffected if the abundance of all alleles fluctuate in unison. However, we argue that large abundance fluctuations can lead to significant genotype frequency fluctuations if different genotypes within a population experience these fluctuations asynchronously. By serially diluting mixtures of two closely related E. coli strains, we show that such asynchrony can occur, leading to giant frequency fluctuations that far exceed expectations from models of genetic drift. We develop a flexible, effective model that explains the abundance fluctuations as arising from correlated offspring numbers between individuals, and the large frequency fluctuations result from even slight decoupling in offspring numbers between genotypes. This model accurately describes the observed abundance and frequency fluctuation scaling behaviors. Our findings suggest chaotic dynamics underpin these giant fluctuations, causing initially similar trajectories to diverge exponentially; subtle environmental changes can be magnified, leading to batch correlations in identical growth conditions. Furthermore, we present evidence that such decoupling noise is also present in mixed-genotype S. cerevisiae populations. We demonstrate that such decoupling noise can strongly influence evolutionary outcomes, in a manner distinct from genetic drift. Given the generic nature of asynchronous fluctuations, we anticipate that they are widespread in biological populations, significantly affecting evolutionary and ecological dynamics.
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Affiliation(s)
- Joao A Ascensao
- Department of Bioengineering, University of California Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA, USA
| | - Kristen Lok
- Department of Bioengineering, University of California Berkeley, Berkeley, CA, USA
- Present affiliation: Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Oskar Hallatschek
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
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5
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Santos MA, Carromeu-Santos A, Quina AS, Antunes MA, Kristensen TN, Santos M, Matos M, Fragata I, Simões P. Experimental Evolution in a Warming World: The Omics Era. Mol Biol Evol 2024; 41:msae148. [PMID: 39034684 PMCID: PMC11331425 DOI: 10.1093/molbev/msae148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 06/25/2024] [Accepted: 07/12/2024] [Indexed: 07/23/2024] Open
Abstract
A comprehensive understanding of the genetic mechanisms that shape species responses to thermal variation is essential for more accurate predictions of the impacts of climate change on biodiversity. Experimental evolution with high-throughput resequencing approaches (evolve and resequence) is a highly effective tool that has been increasingly employed to elucidate the genetic basis of adaptation. The number of thermal evolve and resequence studies is rising, yet there is a dearth of efforts to integrate this new wealth of knowledge. Here, we review this literature showing how these studies have contributed to increase our understanding on the genetic basis of thermal adaptation. We identify two major trends: highly polygenic basis of thermal adaptation and general lack of consistency in candidate targets of selection between studies. These findings indicate that the adaptive responses to specific environments are rather independent. A review of the literature reveals several gaps in the existing research. Firstly, there is a paucity of studies done with organisms of diverse taxa. Secondly, there is a need to apply more dynamic and ecologically relevant thermal environments. Thirdly, there is a lack of studies that integrate genomic changes with changes in life history and behavioral traits. Addressing these issues would allow a more in-depth understanding of the relationship between genotype and phenotype. We highlight key methodological aspects that can address some of the limitations and omissions identified. These include the need for greater standardization of methodologies and the utilization of new technologies focusing on the integration of genomic and phenotypic variation in the context of thermal adaptation.
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Affiliation(s)
- Marta A Santos
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Ana Carromeu-Santos
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Ana S Quina
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Almada, Portugal
| | - Marta A Antunes
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | | | - Mauro Santos
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departament de Genètica i de Microbiologia, Grup de Genòmica, Bioinformàtica i Biologia Evolutiva (GBBE), Universitat Autonòma de Barcelona, Bellaterra, Spain
| | - Margarida Matos
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Inês Fragata
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Simões
- CE3C—Centre for Ecology, Evolution and Environmental Changes & CHANGE, Global Change and Sustainability Institute, Lisboa, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
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6
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Lynch M, Wei W, Ye Z, Pfrender M. The genome-wide signature of short-term temporal selection. Proc Natl Acad Sci U S A 2024; 121:e2307107121. [PMID: 38959040 PMCID: PMC11252749 DOI: 10.1073/pnas.2307107121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/03/2024] [Indexed: 07/04/2024] Open
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multigenerational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a 10-y population-genomic survey of the microcrustacean Daphnia pulex. The genome sequences of [Formula: see text]800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the following: the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals); the preponderance of weak positive selection operating on minor alleles; and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that interannual fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the further development of theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ85287
| | - Zhiqiang Ye
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan430079, China
| | - Michael Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN46556
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7
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Driscoll RMH, Beaudry FEG, Cosgrove EJ, Bowman R, Fitzpatrick JW, Schoech SJ, Chen N. Allele frequency dynamics under sex-biased demography and sex-specific inheritance in a pedigreed jay population. Genetics 2024; 227:iyae075. [PMID: 38722645 PMCID: PMC11228872 DOI: 10.1093/genetics/iyae075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 06/12/2024] Open
Abstract
Sex-biased demography, including sex-biased survival or migration, can alter allele frequency changes across the genome. In particular, we can expect different patterns of genetic variation on autosomes and sex chromosomes due to sex-specific differences in life histories, as well as differences in effective population size, transmission modes, and the strength and mode of selection. Here, we demonstrate the role that sex differences in life history played in shaping short-term evolutionary dynamics across the genome. We used a 25-year pedigree and genomic dataset from a long-studied population of Florida Scrub-Jays (Aphelocoma coerulescens) to directly characterize the relative roles of sex-biased demography and inheritance in shaping genome-wide allele frequency trajectories. We used gene dropping simulations to estimate individual genetic contributions to future generations and to model drift and immigration on the known pedigree. We quantified differential expected genetic contributions of males and females over time, showing the impact of sex-biased dispersal in a monogamous system. Due to female-biased dispersal, more autosomal variation is introduced by female immigrants. However, due to male-biased transmission, more Z variation is introduced by male immigrants. Finally, we partitioned the proportion of variance in allele frequency change through time due to male and female contributions. Overall, most allele frequency change is due to variance in survival and births. Males and females make similar contributions to autosomal allele frequency change, but males make higher contributions to allele frequency change on the Z chromosome. Our work shows the importance of understanding sex-specific demographic processes in characterizing genome-wide allele frequency change in wild populations.
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Affiliation(s)
- Rose M H Driscoll
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Felix E G Beaudry
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Elissa J Cosgrove
- Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Reed Bowman
- Avian Ecology Program, Archbold Biological Station, Venus, FL 33960, USA
| | | | - Stephan J Schoech
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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8
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Angst P, Haag CR, Ben-Ami F, Fields PD, Ebert D. Genome-Wide Allele Frequency Changes Reveal That Dynamic Metapopulations Evolve Differently. Mol Biol Evol 2024; 41:msae128. [PMID: 38935572 PMCID: PMC11229820 DOI: 10.1093/molbev/msae128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/14/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
Two important characteristics of metapopulations are extinction-(re)colonization dynamics and gene flow between subpopulations. These processes can cause strong shifts in genome-wide allele frequencies that are generally not observed in "classical" (large, stable, and panmictic) populations. Subpopulations founded by one or a few individuals, the so-called propagule model, are initially expected to show intermediate allele frequencies at polymorphic sites until natural selection and genetic drift drive allele frequencies toward a mutation-selection-drift equilibrium characterized by a negative exponential-like distribution of the site frequency spectrum. We followed changes in site frequency spectrum distribution in a natural metapopulation of the cyclically parthenogenetic pond-dwelling microcrustacean Daphnia magna using biannual pool-seq samples collected over a 5-yr period from 118 ponds occupied by subpopulations of known age. As expected under the propagule model, site frequency spectra in newly founded subpopulations trended toward intermediate allele frequencies and shifted toward right-skewed distributions as the populations aged. Immigration and subsequent hybrid vigor altered this dynamic. We show that the analysis of site frequency spectrum dynamics is a powerful approach to understand evolution in metapopulations. It allowed us to disentangle evolutionary processes occurring in a natural metapopulation, where many subpopulations evolve in parallel. Thereby, stochastic processes like founder and immigration events lead to a pattern of subpopulation divergence, while genetic drift leads to converging site frequency spectrum distributions in the persisting subpopulations. The observed processes are well explained by the propagule model and highlight that metapopulations evolve differently from classical populations.
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Affiliation(s)
- Pascal Angst
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
| | - Christoph R Haag
- CEFE, Université de Montpellier, CNRS, EPHE, IRD, Montpellier 34293, France
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - Frida Ben-Ami
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
- School of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel 4051, Switzerland
- Tvärminne Zoological Station, University of Helsinki, Hanko 10900, Finland
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9
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Barton N. Limits to species' range: the tension between local and global adaptation. J Evol Biol 2024; 37:605-615. [PMID: 38683160 DOI: 10.1093/jeb/voae052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 04/02/2024] [Accepted: 05/08/2024] [Indexed: 05/01/2024]
Abstract
We know that heritable variation is abundant, and that selection causes all but the smallest populations to rapidly shift beyond their original trait distribution. So then, what limits the range of a species? There are physical constraints and also population genetic limits to the effectiveness of selection, ultimately set by population size. Global adaptation, where the same genotype is favoured over the whole range, is most efficient when based on a multitude of weakly selected alleles and is effective even when local demes are small, provided that there is some gene flow. In contrast, local adaptation is sensitive to gene flow and may require alleles with substantial effect. How can populations combine the advantages of large effective size with the ability to specialise into local niches? To what extent does reproductive isolation help resolve this tension? I address these questions using eco-evolutionary models of polygenic adaptation, contrasting discrete demes with continuousspace.
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Affiliation(s)
- Nicholas Barton
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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10
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Reynes L, Fouqueau L, Aurelle D, Mauger S, Destombe C, Valero M. Temporal genomics help in deciphering neutral and adaptive patterns in the contemporary evolution of kelp populations. J Evol Biol 2024; 37:677-692. [PMID: 38629140 DOI: 10.1093/jeb/voae048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 03/25/2024] [Accepted: 04/15/2024] [Indexed: 06/30/2024]
Abstract
The impact of climate change on populations will be contingent upon their contemporary adaptive evolution. In this study, we investigated the contemporary evolution of 4 populations of the cold-water kelp Laminaria digitata by analyzing their spatial and temporal genomic variations using ddRAD-sequencing. These populations were sampled from the center to the southern margin of its north-eastern Atlantic distribution at 2 time points, spanning at least 2 generations. Through genome scans for local adaptation at a single time point, we identified candidate loci that showed clinal variation correlated with changes in sea surface temperature (SST) along latitudinal gradients. This finding suggests that SST may drive the adaptive response of these kelp populations, although factors such as species' demographic history should also be considered. Additionally, we performed a simulation approach to distinguish the effect of selection from genetic drift in allele frequency changes over time. This enabled the detection of loci in the southernmost population that exhibited temporal differentiation beyond what would be expected from genetic drift alone: these are candidate loci which could have evolved under selection over time. In contrast, we did not detect any outlier locus based on temporal differentiation in the population from the North Sea, which also displayed low and decreasing levels of genetic diversity. The diverse evolutionary scenarios observed among populations can be attributed to variations in the prevalence of selection relative to genetic drift across different environments. Therefore, our study highlights the potential of temporal genomics to offer valuable insights into the contemporary evolution of marine foundation species facing climate change.
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Affiliation(s)
- Lauric Reynes
- IRL 3614, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, Roscoff 29688, France
| | - Louise Fouqueau
- IRL 3614, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, Roscoff 29688, France
| | - Didier Aurelle
- Aix-Marseille Université, Université de Toulon, CNRS, IRD, MIO, 13288 Marseille, France
- Institut de Systématique Évolution Biodiversité (ISYEB, UMR 7205), Muséum National d'Histoire Naturelle, CNRS, EPHE, Sorbonne Université, Paris, France
| | - Stéphane Mauger
- IRL 3614, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, Roscoff 29688, France
| | - Christophe Destombe
- IRL 3614, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, Roscoff 29688, France
| | - Myriam Valero
- IRL 3614, CNRS, Sorbonne Université, Pontificia Universidad Católica de Chile, Universidad Austral de Chile, Station Biologique de Roscoff, Roscoff 29688, France
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11
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Roberts M, Josephs EB. Previously unmeasured genetic diversity explains part of Lewontin's paradox in a k-mer-based meta-analysis of 112 plant species. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.17.594778. [PMID: 38798362 PMCID: PMC11118579 DOI: 10.1101/2024.05.17.594778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
At the molecular level, most evolution is expected to be neutral. A key prediction of this expectation is that the level of genetic diversity in a population should scale with population size. However, as was noted by Richard Lewontin in 1974 and reaffirmed by later studies, the slope of the population size-diversity relationship in nature is much weaker than expected under neutral theory. We hypothesize that one contributor to this paradox is that current methods relying on single nucleotide polymorphisms (SNPs) called from aligning short reads to a reference genome underestimate levels of genetic diversity in many species. To test this idea, we calculated nucleotide diversity ( π ) and k-mer-based metrics of genetic diversity across 112 plant species, amounting to over 205 terabases of DNA sequencing data from 27,488 individual plants. We then compared how these different metrics correlated with proxies of population size that account for both range size and population density variation across species. We found that our population size proxies scaled anywhere from about 3 to over 20 times faster with k-mer diversity than nucleotide diversity after adjusting for evolutionary history, mating system, life cycle habit, cultivation status, and invasiveness. The relationship between k-mer diversity and population size proxies also remains significant after correcting for genome size, whereas the analogous relationship for nucleotide diversity does not. These results suggest that variation not captured by common SNP-based analyses explains part of Lewontin's paradox in plants.
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12
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Glaser-Schmitt A, Ramnarine TJS, Parsch J. Rapid evolutionary change, constraints and the maintenance of polymorphism in natural populations of Drosophila melanogaster. Mol Ecol 2024; 33:e17024. [PMID: 37222070 DOI: 10.1111/mec.17024] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 04/28/2023] [Accepted: 05/05/2023] [Indexed: 05/25/2023]
Abstract
Allele frequencies can shift rapidly within natural populations. Under certain conditions, repeated rapid allele frequency shifts can lead to the long-term maintenance of polymorphism. In recent years, studies of the model insect Drosophila melanogaster have suggested that this phenomenon is more common than previously believed and is often driven by some form of balancing selection, such as temporally fluctuating or sexually antagonistic selection. Here we discuss some of the general insights into rapid evolutionary change revealed by large-scale population genomic studies, as well as the functional and mechanistic causes of rapid adaptation uncovered by single-gene studies. As an example of the latter, we consider a regulatory polymorphism of the D. melanogaster fezzik gene. Polymorphism at this site has been maintained at intermediate frequency over an extended period of time. Regular observations from a single population over a period of 7 years revealed significant differences in the frequency of the derived allele and its variance across collections between the sexes. These patterns are highly unlikely to arise from genetic drift alone or from the action of sexually antagonistic or temporally fluctuating selection individually. Instead, the joint action of sexually antagonistic and temporally fluctuating selection can best explain the observed rapid and repeated allele frequency shifts. Temporal studies such as those reviewed here further our understanding of how rapid changes in selection can lead to the long-term maintenance of polymorphism as well as improve our knowledge of the forces driving and limiting adaptation in nature.
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Affiliation(s)
- Amanda Glaser-Schmitt
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Timothy J S Ramnarine
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - John Parsch
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
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13
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Saubin M, Tellier A, Stoeckel S, Andrieux A, Halkett F. Approximate Bayesian Computation applied to time series of population genetic data disentangles rapid genetic changes and demographic variations in a pathogen population. Mol Ecol 2024; 33:e16965. [PMID: 37150947 DOI: 10.1111/mec.16965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 04/04/2023] [Accepted: 04/12/2023] [Indexed: 05/09/2023]
Abstract
Adaptation can occur at remarkably short timescales in natural populations, leading to drastic changes in phenotypes and genotype frequencies over a few generations only. The inference of demographic parameters can allow understanding how evolutionary forces interact and shape the genetic trajectories of populations during rapid adaptation. Here we propose a new Approximate Bayesian Computation (ABC) framework that couples a forward and individual-based model with temporal genetic data to disentangle genetic changes and demographic variations in a case of rapid adaptation. We test the accuracy of our inferential framework and evaluate the benefit of considering a dense versus sparse sampling. Theoretical investigations demonstrate high accuracy in both model and parameter estimations, even if a strong thinning is applied to time series data. Then, we apply our ABC inferential framework to empirical data describing the population genetic changes of the poplar rust pathogen following a major event of resistance overcoming. We successfully estimate key demographic and genetic parameters, including the proportion of resistant hosts deployed in the landscape and the level of standing genetic variation from which selection occurred. Inferred values are in accordance with our empirical knowledge of this biological system. This new inferential framework, which contrasts with coalescent-based ABC analyses, is promising for a better understanding of evolutionary trajectories of populations subjected to rapid adaptation.
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Affiliation(s)
- Méline Saubin
- Université de Lorraine, INRAE, IAM, Nancy, France
- Department for Life Science Systems, Technical University of Munich, Freising, Germany
| | - Aurélien Tellier
- Department for Life Science Systems, Technical University of Munich, Freising, Germany
| | - Solenn Stoeckel
- INRAE, Agrocampus Ouest, Université de Rennes, IGEPP, Le Rheu, France
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14
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Benfica LF, Brito LF, do Bem RD, de Oliveira LF, Mulim HA, Braga LG, Cyrillo JNSG, Bonilha SFM, Mercadante MEZ. Detection and characterization of copy number variation in three differentially-selected Nellore cattle populations. Front Genet 2024; 15:1377130. [PMID: 38694873 PMCID: PMC11061390 DOI: 10.3389/fgene.2024.1377130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/05/2024] [Indexed: 05/04/2024] Open
Abstract
Introduction: Nellore cattle (Bos taurus indicus) is the main beef cattle breed raised in Brazil. This breed is well adapted to tropical conditions and, more recently, has experienced intensive genetic selection for multiple performance traits. Over the past 43 years, an experimental breeding program has been developed in the Institute of Animal Science (IZ, Sertaozinho, SP, Brazil), which resulted in three differentially-selected lines known as Nellore Control (NeC), Nellore Selection (NeS), and Nellore Traditional (NeT). The primary goal of this selection experiment was to determine the response to selection for yearling weight (YW) and residual feed intake (RFI) on Nellore cattle. The main objectives of this study were to: 1) identify copy number variation (CNVs) in Nellore cattle from three selection lines; 2) identify and characterize CNV regions (CNVR) on these three lines; and 3) perform functional enrichment analyses of the CNVR identified. Results: A total of 14,914 unique CNVs and 1,884 CNVRs were identified when considering all lines as a single population. The CNVRs were non-uniformly distributed across the chromosomes of the three selection lines included in the study. The NeT line had the highest number of CNVRs (n = 1,493), followed by the NeS (n = 823) and NeC (n = 482) lines. The CNVRs covered 23,449,890 bp (0.94%), 40,175,556 bp (1.61%), and 63,212,273 bp (2.54%) of the genome of the NeC, NeS, and NeT lines, respectively. Two CNVRs were commonly identified between the three lines, and six, two, and four exclusive regions were identified for NeC, NeS, and NeT, respectively. All the exclusive regions overlap with important genes, such as SMARCD3, SLC15A1, and MAPK1. Key biological processes associated with the candidate genes were identified, including pathways related to growth and metabolism. Conclusion: This study revealed large variability in CNVs and CNVRs across three Nellore lines differentially selected for YW and RFI. Gene annotation and gene ontology analyses of the exclusive CNVRs to each line revealed specific genes and biological processes involved in the expression of growth and feed efficiency traits. These findings contribute to the understanding of the genetic mechanisms underlying the phenotypic differences among the three Nellore selection lines.
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Affiliation(s)
- Lorena F. Benfica
- Department of Animal Sciences, Purdue University, West Lafayette, IN, United States
- Department of Animal Science, Faculty of Agricultural and Veterinary Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil
| | - Luiz F. Brito
- Department of Animal Sciences, Purdue University, West Lafayette, IN, United States
| | - Ricardo D. do Bem
- Department of Animal Science, Faculty of Agricultural and Veterinary Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil
| | | | - Henrique A. Mulim
- Department of Animal Sciences, Purdue University, West Lafayette, IN, United States
| | - Larissa G. Braga
- Department of Animal Science, Faculty of Agricultural and Veterinary Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | | | - Sarah F. M. Bonilha
- Beef Cattle Research Center, Institute of Animal Science, Sertaozinho, São Paulo, Brazil
| | - Maria Eugenia Z. Mercadante
- Department of Animal Science, Faculty of Agricultural and Veterinary Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil
- Beef Cattle Research Center, Institute of Animal Science, Sertaozinho, São Paulo, Brazil
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15
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Dogantzis KA, Raffiudin R, Putra RE, Shaleh I, Conflitti IM, Pepinelli M, Roberts J, Holmes M, Oldroyd BP, Zayed A, Gloag R. Post-invasion selection acts on standing genetic variation despite a severe founding bottleneck. Curr Biol 2024; 34:1349-1356.e4. [PMID: 38428415 DOI: 10.1016/j.cub.2024.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/12/2023] [Accepted: 02/06/2024] [Indexed: 03/03/2024]
Abstract
Invasive populations often have lower genetic diversity relative to the native-range populations from which they derive.1,2 Despite this, many biological invaders succeed in their new environments, in part due to rapid adaptation.3,4,5,6 Therefore, the role of genetic bottlenecks in constraining the adaptation of invaders is debated.7,8,9,10 Here, we use whole-genome resequencing of samples from a 10-year time-series dataset, representing the natural invasion of the Asian honey bee (Apis cerana) in Australia, to investigate natural selection occurring in the aftermath of a founding event. We find that Australia's A. cerana population was founded by as few as one colony, whose arrival was followed by a period of rapid population expansion associated with an increase of rare variants.11 The bottleneck resulted in a steep loss of overall genetic diversity, yet we nevertheless detected loci with signatures of positive selection during the first years post-invasion. When we investigated the origin of alleles under selection, we found that selection acted primarily on the variation introduced by founders and not on the variants that arose post-invasion by mutation. In all, our data highlight that selection on standing genetic variation can occur in the early years post-invasion, even where founding bottlenecks are severe.
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Affiliation(s)
- Kathleen A Dogantzis
- York University, Department of Biology, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Rika Raffiudin
- IPB University, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor 16680, Indonesia
| | - Ramadhani Eka Putra
- Bandung Institute of Technology, School of Life Sciences and Technology, Bandung 40132, West Java, Indonesia
| | - Ismail Shaleh
- IPB University, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor 16680, Indonesia
| | - Ida M Conflitti
- York University, Department of Biology, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Mateus Pepinelli
- York University, Department of Biology, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - John Roberts
- Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT 2601, Australia
| | - Michael Holmes
- University of Sydney, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia
| | - Benjamin P Oldroyd
- University of Sydney, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia
| | - Amro Zayed
- York University, Department of Biology, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
| | - Rosalyn Gloag
- University of Sydney, School of Life and Environmental Sciences, Sydney, NSW 2006, Australia.
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16
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Grieshop K, Ho EKH, Kasimatis KR. Dominance reversals: the resolution of genetic conflict and maintenance of genetic variation. Proc Biol Sci 2024; 291:20232816. [PMID: 38471544 DOI: 10.1098/rspb.2023.2816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 02/05/2024] [Indexed: 03/14/2024] Open
Abstract
Beneficial reversals of dominance reduce the costs of genetic trade-offs and can enable selection to maintain genetic variation for fitness. Beneficial dominance reversals are characterized by the beneficial allele for a given context (e.g. habitat, developmental stage, trait or sex) being dominant in that context but recessive where deleterious. This context dependence at least partially mitigates the fitness consequence of heterozygotes carrying one non-beneficial allele for their context and can result in balancing selection that maintains alternative alleles. Dominance reversals are theoretically plausible and are supported by mounting empirical evidence. Here, we highlight the importance of beneficial dominance reversals as a mechanism for the mitigation of genetic conflict and review the theory and empirical evidence for them. We identify some areas in need of further research and development and outline three methods that could facilitate the identification of antagonistic genetic variation (dominance ordination, allele-specific expression and allele-specific ATAC-Seq (assay for transposase-accessible chromatin with sequencing)). There is ample scope for the development of new empirical methods as well as reanalysis of existing data through the lens of dominance reversals. A greater focus on this topic will expand our understanding of the mechanisms that resolve genetic conflict and whether they maintain genetic variation.
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Affiliation(s)
- Karl Grieshop
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada M5S 1A1
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Eddie K H Ho
- Department of Biology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202, USA
| | - Katja R Kasimatis
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada M5S 1A1
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
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17
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Bitter MC, Berardi S, Oken H, Huynh A, Schmidt P, Petrov DA. Continuously fluctuating selection reveals extreme granularity and parallelism of adaptive tracking. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.16.562586. [PMID: 37904939 PMCID: PMC10614893 DOI: 10.1101/2023.10.16.562586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
Temporally fluctuating environmental conditions are a ubiquitous feature of natural habitats. Yet, how finely natural populations adaptively track fluctuating selection pressures via shifts in standing genetic variation is unknown. We generated high-frequency, genome-wide allele frequency data from a genetically diverse population of Drosophila melanogaster in extensively replicated field mesocosms from late June to mid-December, a period of ∼12 generations. Adaptation throughout the fundamental ecological phases of population expansion, peak density, and collapse was underpinned by extremely rapid, parallel changes in genomic variation across replicates. Yet, the dominant direction of selection fluctuated repeatedly, even within each of these ecological phases. Comparing patterns of allele frequency change to an independent dataset procured from the same experimental system demonstrated that the targets of selection are predictable across years. In concert, our results reveal fitness-relevance of standing variation that is likely to be masked by inference approaches based on static population sampling, or insufficiently resolved time-series data. We propose such fine-scaled temporally fluctuating selection may be an important force maintaining functional genetic variation in natural populations and an important stochastic force affecting levels of standing genetic variation genome-wide.
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18
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Simon A, Coop G. The contribution of gene flow, selection, and genetic drift to five thousand years of human allele frequency change. Proc Natl Acad Sci U S A 2024; 121:e2312377121. [PMID: 38363870 PMCID: PMC10907250 DOI: 10.1073/pnas.2312377121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 01/09/2024] [Indexed: 02/18/2024] Open
Abstract
Genomic time series from experimental evolution studies and ancient DNA datasets offer us a chance to directly observe the interplay of various evolutionary forces. We show how the genome-wide variance in allele frequency change between two time points can be decomposed into the contributions of gene flow, genetic drift, and linked selection. In closed populations, the contribution of linked selection is identifiable because it creates covariances between time intervals, and genetic drift does not. However, repeated gene flow between populations can also produce directionality in allele frequency change, creating covariances. We show how to accurately separate the fraction of variance in allele frequency change due to admixture and linked selection in a population receiving gene flow. We use two human ancient DNA datasets, spanning around 5,000 y, as time transects to quantify the contributions to the genome-wide variance in allele frequency change. We find that a large fraction of genome-wide change is due to gene flow. In both cases, after correcting for known major gene flow events, we do not observe a signal of genome-wide linked selection. Thus despite the known role of selection in shaping long-term polymorphism levels, and an increasing number of examples of strong selection on single loci and polygenic scores from ancient DNA, it appears to be gene flow and drift, and not selection, that are the main determinants of recent genome-wide allele frequency change. Our approach should be applicable to the growing number of contemporary and ancient temporal population genomics datasets.
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Affiliation(s)
- Alexis Simon
- Center for Population Biology, University of California, Davis, CA95616
- Department of Evolution and Ecology, University of California, Davis, CA95616
| | - Graham Coop
- Center for Population Biology, University of California, Davis, CA95616
- Department of Evolution and Ecology, University of California, Davis, CA95616
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19
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Nunez JCB, Lenhart BA, Bangerter A, Murray CS, Mazzeo GR, Yu Y, Nystrom TL, Tern C, Erickson PA, Bergland AO. A cosmopolitan inversion facilitates seasonal adaptation in overwintering Drosophila. Genetics 2024; 226:iyad207. [PMID: 38051996 PMCID: PMC10847723 DOI: 10.1093/genetics/iyad207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023] Open
Abstract
Fluctuations in the strength and direction of natural selection through time are a ubiquitous feature of life on Earth. One evolutionary outcome of such fluctuations is adaptive tracking, wherein populations rapidly adapt from standing genetic variation. In certain circumstances, adaptive tracking can lead to the long-term maintenance of functional polymorphism despite allele frequency change due to selection. Although adaptive tracking is likely a common process, we still have a limited understanding of aspects of its genetic architecture and its strength relative to other evolutionary forces such as drift. Drosophila melanogaster living in temperate regions evolve to track seasonal fluctuations and are an excellent system to tackle these gaps in knowledge. By sequencing orchard populations collected across multiple years, we characterized the genomic signal of seasonal demography and identified that the cosmopolitan inversion In(2L)t facilitates seasonal adaptive tracking and shows molecular footprints of selection. A meta-analysis of phenotypic studies shows that seasonal loci within In(2L)t are associated with behavior, life history, physiology, and morphological traits. We identify candidate loci and experimentally link them to phenotype. Our work contributes to our general understanding of fluctuating selection and highlights the evolutionary outcome and dynamics of contemporary selection on inversions.
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Affiliation(s)
- Joaquin C B Nunez
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
- Department of Biology, University of Vermont, 109 Carrigan Drive, Burlington, VT 05405, USA
| | - Benedict A Lenhart
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Alyssa Bangerter
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Connor S Murray
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Giovanni R Mazzeo
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Yang Yu
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Taylor L Nystrom
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Courtney Tern
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
| | - Priscilla A Erickson
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
- Department of Biology, University of Richmond, 138 UR Drive, Richmond, VA 23173, USA
| | - Alan O Bergland
- Department of Biology, University of Virginia, 90 Geldard Drive, Charlottesville, VA 22901, USA
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20
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Howe NS, Hale MC, Waters CD, Schaal SM, Shedd KR, Larson WA. Genomic evidence for domestication selection in three hatchery populations of Chinook salmon, Oncorhynchus tshawytscha. Evol Appl 2024; 17:e13656. [PMID: 38357359 PMCID: PMC10866082 DOI: 10.1111/eva.13656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
Fish hatcheries are widely used to enhance fisheries and supplement declining wild populations. However, substantial evidence suggests that hatchery fish are subject to differential selection pressures compared to their wild counterparts. Domestication selection, or adaptation to the hatchery environment, poses a risk to wild populations if traits specific to success in the hatchery environment have a genetic component and there is subsequent introgression between hatchery and wild fish. Few studies have investigated domestication selection in hatcheries on a genomic level, and even fewer have done so in parallel across multiple hatchery-wild population pairs. In this study, we used low-coverage whole-genome sequencing to investigate signals of domestication selection in three separate hatchery populations of Chinook salmon, Oncorhynchus tshawytscha, after approximately seven generations of divergence from their corresponding wild progenitor populations. We sequenced 192 individuals from populations across Southeast Alaska and estimated genotype likelihoods at over six million loci. We discovered a total of 14 outlier peaks displaying high genetic differentiation (F ST) between hatchery-wild pairs, although no peaks were shared across the three comparisons. Peaks were small (53 kb on average) and often displayed elevated absolute genetic divergence (D xy) and linkage disequilibrium, suggesting some level of domestication selection has occurred. Our study provides evidence that domestication selection can lead to genetic differences between hatchery and wild populations in only a few generations. Additionally, our data suggest that population-specific adaptation to hatchery environments likely occurs through different genetic pathways, even for populations with similar standing genetic variation. These results highlight the need to collect paired genotype-phenotype data to understand how domestication may be affecting fitness and to identify potential management practices that may mitigate genetic risks despite multiple pathways of domestication.
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Affiliation(s)
- Natasha S. Howe
- Department of BiologyTexas Christian UniversityFort WorthTexasUSA
| | - Matthew C. Hale
- Department of BiologyTexas Christian UniversityFort WorthTexasUSA
| | - Charles D. Waters
- National Oceanographic and Atmospheric Administration, National Marine Fisheries ServiceAlaska Fisheries Science Center, Auke Bay LaboratoriesJuneauAlaskaUSA
| | - Sara M. Schaal
- National Oceanographic and Atmospheric Administration, National Marine Fisheries ServiceAlaska Fisheries Science Center, Auke Bay LaboratoriesJuneauAlaskaUSA
| | - Kyle R. Shedd
- Alaska Department of Fish and Game, Division of Commercial FisheriesGene Conservation LaboratoryAnchorageAlaskaUSA
| | - Wesley A. Larson
- National Oceanographic and Atmospheric Administration, National Marine Fisheries ServiceAlaska Fisheries Science Center, Auke Bay LaboratoriesJuneauAlaskaUSA
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21
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Simon A, Coop G. The contribution of gene flow, selection, and genetic drift to five thousand years of human allele frequency change. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.11.548607. [PMID: 37503227 PMCID: PMC10370008 DOI: 10.1101/2023.07.11.548607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Genomic time series from experimental evolution studies and ancient DNA datasets offer us a chance to directly observe the interplay of various evolutionary forces. We show how the genome-wide variance in allele frequency change between two time points can be decomposed into the contributions of gene flow, genetic drift, and linked selection. In closed populations, the contribution of linked selection is identifiable because it creates covariances between time intervals, and genetic drift does not. However, repeated gene flow between populations can also produce directionality in allele frequency change, creating covariances. We show how to accurately separate the fraction of variance in allele frequency change due to admixture and linked selection in a population receiving gene flow. We use two human ancient DNA datasets, spanning around 5,000 years, as time transects to quantify the contributions to the genome-wide variance in allele frequency change. We find that a large fraction of genome-wide change is due to gene flow. In both cases, after correcting for known major gene flow events, we do not observe a signal of genome-wide linked selection. Thus despite the known role of selection in shaping long-term polymorphism levels, and an increasing number of examples of strong selection on single loci and polygenic scores from ancient DNA, it appears to be gene flow and drift, and not selection, that are the main determinants of recent genome-wide allele frequency change. Our approach should be applicable to the growing number of contemporary and ancient temporal population genomics datasets.
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Affiliation(s)
- Alexis Simon
- Center for Population Biology, University of California, Davis, CA 95616
- Department of Evolution and Ecology, University of California, Davis, CA 95616
| | - Graham Coop
- Center for Population Biology, University of California, Davis, CA 95616
- Department of Evolution and Ecology, University of California, Davis, CA 95616
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22
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Pinsky ML, Clark RD, Bos JT. Coral Reef Population Genomics in an Age of Global Change. Annu Rev Genet 2023; 57:87-115. [PMID: 37384733 DOI: 10.1146/annurev-genet-022123-102748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
Coral reefs are both exceptionally biodiverse and threatened by climate change and other human activities. Here, we review population genomic processes in coral reef taxa and their importance for understanding responses to global change. Many taxa on coral reefs are characterized by weak genetic drift, extensive gene flow, and strong selection from complex biotic and abiotic environments, which together present a fascinating test of microevolutionary theory. Selection, gene flow, and hybridization have played and will continue to play an important role in the adaptation or extinction of coral reef taxa in the face of rapid environmental change, but research remains exceptionally limited compared to the urgent needs. Critical areas for future investigation include understanding evolutionary potential and the mechanisms of local adaptation, developing historical baselines, and building greater research capacity in the countries where most reef diversity is concentrated.
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Affiliation(s)
- Malin L Pinsky
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA;
| | - René D Clark
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
| | - Jaelyn T Bos
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, USA
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23
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Babik W, Dudek K, Marszałek M, Palomar G, Antunes B, Sniegula S. The genomic response to urbanization in the damselfly Ischnura elegans. Evol Appl 2023; 16:1805-1818. [PMID: 38029064 PMCID: PMC10681423 DOI: 10.1111/eva.13603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 09/19/2023] [Indexed: 12/01/2023] Open
Abstract
The complex and rapid environmental changes brought about by urbanization pose significant challenges to organisms. The multifaceted effects of urbanization often make it difficult to define and pinpoint the very nature of adaptive urban phenotypes. In such situations, scanning genomes for regions differentiated between urban and non-urban populations may be an attractive approach. Here, we investigated the genomic signatures of adaptation to urbanization in the damselfly Ischnura elegans sampled from 31 rural and urban localities in three geographic regions: southern and northern Poland, and southern Sweden. Genome-wide variation was assessed using more than 370,000 single nucleotide polymorphisms (SNPs) genotyped by ddRADseq. Associations between SNPs and the level of urbanization were tested using two genetic environment association methods: Latent Factors Mixed Models and BayPass. While we found numerous candidate SNPs and a highly significant overlap between candidates identified by the two methods within the geographic regions, there was a distinctive lack of repeatability between the geographic regions both at the level of individual SNPs and of genomic regions. However, we found "synapse organization" at the top of the functional categories enriched among the genes located in the proximity of the candidate urbanization SNPs. Interestingly, the overall significance of "synapse organization" was built up by the accretion of different genes associated with candidate SNPs in different geographic regions. This finding is consistent with the highly polygenic nature of adaptation, where the response may be achieved through a subtle adjustment of allele frequencies in different genes that contribute to adaptive phenotypes. Taken together, our results point to a polygenic adaptive response in the nervous system, specifically implicating genes involved in synapse organization, which mirrors the findings from several genomic and behavioral studies of adaptation to urbanization in other taxa.
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Affiliation(s)
- W. Babik
- Faculty of Biology, Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - K. Dudek
- Faculty of Biology, Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - M. Marszałek
- Faculty of Biology, Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - G. Palomar
- Faculty of Biology, Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
- Department of Genetics, Physiology and Microbiology, Faculty of Biological SciencesComplutense University of MadridMadridSpain
| | - B. Antunes
- Faculty of Biology, Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - S. Sniegula
- Department of Ecosystem Conservation, Institute of Nature ConservationPolish Academy of SciencesKrakówPoland
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24
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Reid BN, Star B, Pinsky ML. Detecting parallel polygenic adaptation to novel evolutionary pressure in wild populations: a case study in Atlantic cod ( Gadus morhua). Philos Trans R Soc Lond B Biol Sci 2023; 378:20220190. [PMID: 37246382 DOI: 10.1098/rstb.2022.0190] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/13/2023] [Indexed: 05/30/2023] Open
Abstract
Populations can adapt to novel selection pressures through dramatic frequency changes in a few genes of large effect or subtle shifts in many genes of small effect. The latter (polygenic adaptation) is expected to be the primary mode of evolution for many life-history traits but tends to be more difficult to detect than changes in genes of large effect. Atlantic cod (Gadus morhua) were subjected to intense fishing pressure over the twentieth century, leading to abundance crashes and a phenotypic shift toward earlier maturation across many populations. Here, we use spatially replicated temporal genomic data to test for a shared polygenic adaptive response to fishing using methods previously applied to evolve-and-resequence experiments. Cod populations on either side of the Atlantic show covariance in allele frequency change across the genome that are characteristic of recent polygenic adaptation. Using simulations, we demonstrate that the degree of covariance in allele frequency change observed in cod is unlikely to be explained by neutral processes or background selection. As human pressures on wild populations continue to increase, understanding and attributing modes of adaptation using methods similar to those demonstrated here will be important in identifying the capacity for adaptive responses and evolutionary rescue. This article is part of the theme issue 'Detecting and attributing the causes of biodiversity change: needs, gaps and solutions'.
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Affiliation(s)
- Brendan N Reid
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ 08540, USA
| | - Bastiaan Star
- Center for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, PO Box 1066, Blindern, 0316 Oslo, Norway
| | - Malin L Pinsky
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ 08540, USA
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25
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Whitehouse LS, Schrider DR. Timesweeper: accurately identifying selective sweeps using population genomic time series. Genetics 2023; 224:iyad084. [PMID: 37157914 PMCID: PMC10324941 DOI: 10.1093/genetics/iyad084] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 07/25/2022] [Accepted: 04/25/2023] [Indexed: 05/10/2023] Open
Abstract
Despite decades of research, identifying selective sweeps, the genomic footprints of positive selection, remains a core problem in population genetics. Of the myriad methods that have been developed to tackle this task, few are designed to leverage the potential of genomic time-series data. This is because in most population genetic studies of natural populations, only a single period of time can be sampled. Recent advancements in sequencing technology, including improvements in extracting and sequencing ancient DNA, have made repeated samplings of a population possible, allowing for more direct analysis of recent evolutionary dynamics. Serial sampling of organisms with shorter generation times has also become more feasible due to improvements in the cost and throughput of sequencing. With these advances in mind, here we present Timesweeper, a fast and accurate convolutional neural network-based tool for identifying selective sweeps in data consisting of multiple genomic samplings of a population over time. Timesweeper analyzes population genomic time-series data by first simulating training data under a demographic model appropriate for the data of interest, training a one-dimensional convolutional neural network on said simulations, and inferring which polymorphisms in this serialized data set were the direct target of a completed or ongoing selective sweep. We show that Timesweeper is accurate under multiple simulated demographic and sampling scenarios, identifies selected variants with high resolution, and estimates selection coefficients more accurately than existing methods. In sum, we show that more accurate inferences about natural selection are possible when genomic time-series data are available; such data will continue to proliferate in coming years due to both the sequencing of ancient samples and repeated samplings of extant populations with faster generation times, as well as experimentally evolved populations where time-series data are often generated. Methodological advances such as Timesweeper thus have the potential to help resolve the controversy over the role of positive selection in the genome. We provide Timesweeper as a Python package for use by the community.
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Affiliation(s)
- Logan S Whitehouse
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Daniel R Schrider
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27514, USA
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26
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Lynch M, Wei W, Ye Z, Pfrender M. The Genome-wide Signature of Short-term Temporal Selection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538790. [PMID: 37162919 PMCID: PMC10168312 DOI: 10.1101/2023.04.28.538790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multi-generational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a nine-year population-genomic survey of the microcrustacean Daphnia pulex. The genome-sequences of > 800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals), the preponderance of weak negative selection operating on minor alleles, and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the development of new theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Michael Pfrender
- Department of Biological Sciences, Notre Dame University, Notre Dame, IN 46556
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27
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Gauzere J, Pemberton JM, Slate J, Morris A, Morris S, Walling CA, Johnston SE. A polygenic basis for birth weight in a wild population of red deer (Cervus elaphus). G3 (BETHESDA, MD.) 2023; 13:jkad018. [PMID: 36652410 PMCID: PMC10085764 DOI: 10.1093/g3journal/jkad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/09/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023]
Abstract
The genetic architecture of traits under selection has important consequences for the response to selection and potentially for population viability. Early QTL mapping studies in wild populations have reported loci with large effect on trait variation. However, these results are contradicted by more recent genome-wide association analyses, which strongly support the idea that most quantitative traits have a polygenic basis. This study aims to re-evaluate the genetic architecture of a key morphological trait, birth weight, in a wild population of red deer (Cervus elaphus), using genomic approaches. A previous study using 93 microsatellite and allozyme markers and linkage mapping on a kindred of 364 deer detected a pronounced QTL on chromosome 21 explaining 29% of the variance in birth weight, suggesting that this trait is partly controlled by genes with large effects. Here, we used data for more than 2,300 calves genotyped at >39,000 SNP markers and two approaches to characterise the genetic architecture of birth weight. First, we performed a genome-wide association (GWA) analysis, using a genomic relatedness matrix to account for population structure. We found no SNPs significantly associated with birth weight. Second, we used genomic prediction to estimate the proportion of variance explained by each SNP and chromosome. This analysis confirmed that most genetic variance in birth weight was explained by loci with very small effect sizes. Third, we found that the proportion of variance explained by each chromosome was slightly positively correlated with its size. These three findings highlight a highly polygenic architecture for birth weight, which contradicts the previous QTL study. These results are probably explained by the differences in how associations are modelled between QTL mapping and GWA. Our study suggests that models of polygenic adaptation are the most appropriate to study the evolutionary trajectory of this trait.
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Affiliation(s)
- Julie Gauzere
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
- AGAP, Université Montpellier, CIRAD, INRAE, Institut Agro, 34090 Montpellier, France
| | | | - Jon Slate
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Alison Morris
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Sean Morris
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Craig A Walling
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK
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28
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Fluctuating selection and the determinants of genetic variation. Trends Genet 2023; 39:491-504. [PMID: 36890036 DOI: 10.1016/j.tig.2023.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 02/01/2023] [Accepted: 02/07/2023] [Indexed: 03/08/2023]
Abstract
Recent studies of cosmopolitan Drosophila populations have found hundreds to thousands of genetic loci with seasonally fluctuating allele frequencies, bringing temporally fluctuating selection to the forefront of the historical debate surrounding the maintenance of genetic variation in natural populations. Numerous mechanisms have been explored in this longstanding area of research, but these exciting empirical findings have prompted several recent theoretical and experimental studies that seek to better understand the drivers, dynamics, and genome-wide influence of fluctuating selection. In this review, we evaluate the latest evidence for multilocus fluctuating selection in Drosophila and other taxa, highlighting the role of potential genetic and ecological mechanisms in maintaining these loci and their impacts on neutral genetic variation.
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29
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Li Y, Barton JP. Estimating linkage disequilibrium and selection from allele frequency trajectories. Genetics 2023; 223:iyac189. [PMID: 36610715 PMCID: PMC9991507 DOI: 10.1093/genetics/iyac189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 10/14/2022] [Accepted: 12/11/2022] [Indexed: 01/09/2023] Open
Abstract
Genetic sequences collected over time provide an exciting opportunity to study natural selection. In such studies, it is important to account for linkage disequilibrium to accurately measure selection and to distinguish between selection and other effects that can cause changes in allele frequencies, such as genetic hitchhiking or clonal interference. However, most high-throughput sequencing methods cannot directly measure linkage due to short-read lengths. Here we develop a simple method to estimate linkage disequilibrium from time-series allele frequencies. This reconstructed linkage information can then be combined with other inference methods to infer the fitness effects of individual mutations. Simulations show that our approach reliably outperforms inference that ignores linkage disequilibrium and, with sufficient sampling, performs similarly to inference using the true linkage information. We also introduce two regularization methods derived from random matrix theory that help to preserve its performance under limited sampling effects. Overall, our method enables the use of linkage-aware inference methods even for data sets where only allele frequency time series are available.
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Affiliation(s)
- Yunxiao Li
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
| | - John P Barton
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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30
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DeVos TB, Bock DG, Kolbe JJ. Rapid introgression of non-native alleles following hybridization between a native Anolis lizard species and a cryptic invader across an urban landscape. Mol Ecol 2023; 32:2930-2944. [PMID: 36811388 DOI: 10.1111/mec.16897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 02/14/2023] [Accepted: 02/20/2023] [Indexed: 02/24/2023]
Abstract
Invasive species can impact native populations through competition, predation, habitat alteration, and disease transmission, but also genetically through hybridization. Potential outcomes of hybridization span the continuum from extinction to hybrid speciation and can be further complicated by anthropogenic habitat disturbance. Hybridization between the native green anole lizard (Anolis carolinensis) and a morphologically similar invader (A. porcatus) in south Florida provides an ideal opportunity to study interspecific admixture across a heterogeneous landscape. We used reduced-representation sequencing to describe introgression in this hybrid system and to test for a relationship between urbanization and non-native ancestry. Our findings indicate that hybridization between green anole lineages was probably a limited, historic event, producing a hybrid population characterized by a diverse continuum of ancestry proportions. Genomic cline analyses revealed rapid introgression and disproportionate representation of non-native alleles at many loci and no evidence for reproductive isolation between parental species. Three loci were associated with urban habitat characteristics; urbanization and non-native ancestry were positively correlated, although this relationship did not remain significant when accounting for spatial nonindependence. Ultimately, our study demonstrates the persistence of non-native genetic material even in the absence of ongoing immigration, indicating that selection favouring non-native alleles can override the demographic limitation of low propagule pressure. We also note that not all outcomes of admixture between native and non-native species should be considered intrinsically negative. Hybridization with ecologically robust invaders can lead to adaptive introgression, which may facilitate the long-term survival of native populations otherwise unable to adapt to anthropogenically mediated global change.
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Affiliation(s)
- Tyler B DeVos
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Dan G Bock
- Department of Biology, Washington University, St. Louis, Missouri, USA
| | - Jason J Kolbe
- Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island, USA
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31
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Steyn Y, Lawlor T, Masuda Y, Tsuruta S, Legarra A, Lourenco D, Misztal I. Nonparallel genome changes within subpopulations over time contributed to genetic diversity within the US Holstein population. J Dairy Sci 2023; 106:2551-2572. [PMID: 36797192 DOI: 10.3168/jds.2022-21914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 10/03/2022] [Indexed: 02/16/2023]
Abstract
Maintaining genetic variation in a population is important for long-term genetic gain. The existence of subpopulations within a breed helps maintain genetic variation and diversity. The 20,990 genotyped animals, representing the breeding animals in the year 2014, were identified as the sires of animals born after 2010 with at least 25 progenies, and females measured for type traits within the last 2 yr of data. K-means clustering with 5 clusters (C1, C2, C3, C4, and C5) was applied to the genomic relationship matrix based on 58,990 SNP markers to stratify the selected candidates into subpopulations. The general higher inbreeding resulting from within-cluster mating than across-cluster mating suggests the successful stratification into genetically different groups. The largest cluster (C4) contained animals that were less related to each animal within and across clusters. The average fixation index was 0.03, indicating that the populations were differentiated, and allele differences across the subpopulations were not due to drift alone. Starting with the selected candidates within each cluster, a family unit was identified by tracing back through the pedigree, identifying the genotyped ancestors, and assigning them to a pseudogeneration. Each of the 5 families (F1, F2, F3, F4, and F5) was traced back for 10 generations, allowing for changes in frequency of individual SNPs over time to be observed, which we call allele frequencies change. Alternative procedures were used to identify SNPs changing in a parallel or nonparallel way across families. For example, markers that have changed the most in the whole population, markers that have changed differently across families, and genes previously identified as those that have changed in allele frequency. The genomic trajectory taken by each family involves selective sweeps, polygenic changes, hitchhiking, and epistasis. The replicate frequency spectrum was used to measure the similarity of change across families and showed that populations have changed differently. The proportion of markers that reversed direction in allele frequency change varied from 0.00 to 0.02 if the rate of change was greater than 0.02 per generation, or from 0.14 to 0.24 if the rate of change was greater than 0.005 per generation within each family. Cluster-specific SNP effects for stature were estimated using only females and applied to obtain indirect genomic predictions for males. Reranking occurs depending on SNP effects used. Additive genetic correlations between clusters show possible differences in populations. Further research is required to determine how this knowledge can be applied to maintain diversity and optimize selection decisions in the future.
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Affiliation(s)
- Y Steyn
- Department of Animal and Dairy Science, University of Georgia, 425 River Road, Athens 30602.
| | - T Lawlor
- Holstein Association USA Inc., Brattleboro, VT 05302
| | - Y Masuda
- Department of Animal and Dairy Science, University of Georgia, 425 River Road, Athens 30602
| | - S Tsuruta
- Department of Animal and Dairy Science, University of Georgia, 425 River Road, Athens 30602
| | - A Legarra
- GenPhySE, INRA, INPT, ENVT, Université de Toulouse, Castanet-Tolosan 31520, France
| | - D Lourenco
- Department of Animal and Dairy Science, University of Georgia, 425 River Road, Athens 30602
| | - I Misztal
- Department of Animal and Dairy Science, University of Georgia, 425 River Road, Athens 30602
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32
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Jia Y, Xu M, Hu H, Chapman B, Watt C, Buerte B, Han N, Zhu M, Bian H, Li C, Zeng Z. Comparative gene retention analysis in barley, wild emmer, and bread wheat pangenome lines reveals factors affecting gene retention following gene duplication. BMC Biol 2023; 21:25. [PMID: 36747211 PMCID: PMC9903521 DOI: 10.1186/s12915-022-01503-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 12/16/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Gene duplication is a prevalent phenomenon and a major driving force underlying genome evolution. The process leading to the fixation of gene duplicates following duplication is critical to understand how genome evolves but remains fragmentally understood. Most previous studies on gene retention are based on gene duplicate analyses in single reference genome. No population-based comparative gene retention analysis has been performed to date. RESULTS Taking advantage of recently published genomic data in Triticeae, we dissected a divergent homogentisate phytyltransferase (HPT2) lineage caught in the middle stage of gene fixation following duplication. The presence/absence of HPT2 in barley (diploid), wild emmer (tetraploid), and bread wheat (hexaploid) pangenome lines appears to be associated with gene dosage constraint and environmental adaption. Based on these observations, we adopted a phylogeny-based orthology inference approach and performed comparative gene retention analyses across barley, wild emmer, and bread wheat. This led to the identification of 326 HPT2-pattern-like genes at whole genome scale, representing a pool of gene duplicates in the middle stage of gene fixation. Majority of these HPT2-pattern-like genes were identified as small-scale duplicates, such as dispersed, tandem, and proximal duplications. Natural selection analyses showed that HPT2-pattern-like genes have experienced relaxed selection pressure, which is generally accompanied with partial positive selection and transcriptional divergence. Functional enrichment analyses showed that HPT2-pattern-like genes are over-represented with molecular-binding and defense response functions, supporting the potential role of environmental adaption during gene retention. We also observed that gene duplicates from larger gene family are more likely to be lost, implying a gene dosage constraint effect. Further comparative gene retention analysis in barley and bread wheat pangenome lines revealed combined effects of species-specific selection and gene dosage constraint. CONCLUSIONS Comparative gene retention analyses at the population level support gene dosage constraint, environmental adaption, and species-specific selection as three factors that may affect gene retention following gene duplication. Our findings shed light on the evolutionary process leading to the retention of newly formed gene duplicates and will greatly improve our understanding on genome evolution via duplication.
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Affiliation(s)
- Yong Jia
- grid.1025.60000 0004 0436 6763Western Crop Genetic Alliance, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia ,grid.1025.60000 0004 0436 6763Western Australian State Agricultural Biotechnology Centre, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia
| | - Mingrui Xu
- grid.410595.c0000 0001 2230 9154College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121 China
| | - Haifei Hu
- grid.1025.60000 0004 0436 6763Western Crop Genetic Alliance, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia ,grid.1025.60000 0004 0436 6763Western Australian State Agricultural Biotechnology Centre, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia
| | - Brett Chapman
- grid.1025.60000 0004 0436 6763Western Crop Genetic Alliance, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia ,grid.1025.60000 0004 0436 6763Western Australian State Agricultural Biotechnology Centre, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia
| | - Calum Watt
- grid.1025.60000 0004 0436 6763Western Australian State Agricultural Biotechnology Centre, Murdoch University, 90 South Street, Murdoch, WA 6150 Australia ,grid.516230.30000 0005 0233 6218Intergrain Pty Ltd, Bibra Lake, WA 6163 Australia
| | - B. Buerte
- grid.13402.340000 0004 1759 700XInstitute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Ning Han
- grid.13402.340000 0004 1759 700XInstitute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Muyuan Zhu
- grid.13402.340000 0004 1759 700XInstitute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Hongwu Bian
- Institute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
| | - Chengdao Li
- Western Crop Genetic Alliance, College of Science, Health, Engineering and Education, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia. .,Western Australian State Agricultural Biotechnology Centre, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia. .,Department of Primary Industries and Regional Development, 3-Baron-Hay Court, South Perth, WA, 6151, Australia.
| | - Zhanghui Zeng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 311121, China. .,Institute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China. .,Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, Hangzhou, 311121, China.
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33
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Andrews KR, Seaborn T, Egan JP, Fagnan MW, New DD, Chen Z, Hohenlohe PA, Waits LP, Caudill CC, Narum SR. Whole genome resequencing identifies local adaptation associated with environmental variation for redband trout. Mol Ecol 2023; 32:800-818. [PMID: 36478624 PMCID: PMC9905331 DOI: 10.1111/mec.16810] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 11/20/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Aquatic ectotherms are predicted to harbour genomic signals of local adaptation resulting from selective pressures driven by the strong influence of climate conditions on body temperature. We investigated local adaptation in redband trout (Oncorhynchus mykiss gairdneri) using genome scans for 547 samples from 11 populations across a wide range of habitats and thermal gradients in the interior Columbia River. We estimated allele frequencies for millions of single nucleotide polymorphism loci (SNPs) across populations using low-coverage whole genome resequencing, and used population structure outlier analyses to identify genomic regions under divergent selection between populations. Twelve genomic regions showed signatures of local adaptation, including two regions associated with genes known to influence migration and developmental timing in salmonids (GREB1L, ROCK1, SIX6). Genotype-environment association analyses indicated that diurnal temperature variation was a strong driver of local adaptation, with signatures of selection driven primarily by divergence of two populations in the northern extreme of the subspecies range. We also found evidence for adaptive differences between high-elevation desert vs. montane habitats at a smaller geographical scale. Finally, we estimated vulnerability of redband trout to future climate change using ecological niche modelling and genetic offset analyses under two climate change scenarios. These analyses predicted substantial habitat loss and strong genetic shifts necessary for adaptation to future habitats, with the greatest vulnerability predicted for high-elevation desert populations. Our results provide new insight into the complexity of local adaptation in salmonids, and important predictions regarding future responses of redband trout to climate change.
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Affiliation(s)
- Kimberly R Andrews
- Institute for Interdisciplinary Data Sciences (IIDS), University of Idaho, Moscow, Idaho, USA
| | - Travis Seaborn
- Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, Moscow, Idaho, USA
| | - Joshua P Egan
- Department of Biological Sciences, College of Science, University of Idaho, Moscow, Idaho, USA.,Bell Museum of Natural History, University of Minnesota, Saint Paul, Minnesota, USA
| | - Matthew W Fagnan
- Institute for Interdisciplinary Data Sciences (IIDS), University of Idaho, Moscow, Idaho, USA
| | - Daniel D New
- Institute for Interdisciplinary Data Sciences (IIDS), University of Idaho, Moscow, Idaho, USA
| | - Zhongqi Chen
- Aquaculture Research Institute, University of Idaho, Hagerman, Idaho, USA
| | - Paul A Hohenlohe
- Department of Biological Sciences, College of Science, University of Idaho, Moscow, Idaho, USA
| | - Lisette P Waits
- Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, Moscow, Idaho, USA
| | - Christopher C Caudill
- Department of Fish and Wildlife Sciences, College of Natural Resources, University of Idaho, Moscow, Idaho, USA
| | - Shawn R Narum
- Aquaculture Research Institute, University of Idaho, Hagerman, Idaho, USA.,Columbia River Inter-Tribal Fish Commission, Hagerman, Idaho, USA
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34
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Pfenninger M, Foucault Q, Waldvogel AM, Feldmeyer B. Selective effects of a short transient environmental fluctuation on a natural population. Mol Ecol 2023; 32:335-349. [PMID: 36282585 DOI: 10.1111/mec.16748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 09/21/2022] [Accepted: 10/21/2022] [Indexed: 01/11/2023]
Abstract
Natural populations experience continuous and often transient changes of environmental conditions. These in turn may result in fluctuating selection pressures leading to variable demographic and evolutionary population responses. Rapid adaptation as short-term response to a sudden environmental change has in several cases been attributed to polygenic traits, but the underlying genomic dynamics and architecture are poorly understood. In this study, we took advantage of a natural experiment in an insect population of the non-biting midge Chironomus riparius by monitoring genome-wide allele frequencies before and after a cold snap event. Whole genome pooled sequencing of time series samples revealed 10 selected haplotypes carrying ancient polymorphisms, partially with signatures of balancing selection. By constantly cold exposing genetically variable individuals in the laboratory, we could demonstrate with whole genome resequencing (i) that among the survivors, the same alleles rose in frequency as in the wild, and (ii) that the identified variants additively predicted fitness (survival time) of its bearers. Finally, by simultaneously sequencing the genome and the transcriptome of cold exposed individuals we could tentatively link some of the selected SNPs to the cis- and trans-regulation of genes and pathways known to be involved in cold response of insects, such as cytochrome P450 and fatty acid metabolism. Altogether, our results shed light on the strength and speed of selection in natural populations and the genomic architecture of its underlying polygenic trait. Population genomic time series data thus appear as promising tool for measuring the selective tracking of fluctuating selection in natural populations.
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Affiliation(s)
- Markus Pfenninger
- Department of Molecular Ecology, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany.,LOEWE Centre for Translational Biodiversity Genomics, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany.,Institute for Molecular and Organismic Evolution, Johannes Gutenberg University, Mainz, Germany
| | - Quentin Foucault
- Department of Molecular Ecology, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
| | - Ann-Marie Waldvogel
- Department of Ecological Genomics, Institute of Zoology, University of Cologne, Köln, Germany
| | - Barbara Feldmeyer
- Department of Molecular Ecology, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
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35
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Barata C, Borges R, Kosiol C. Bait-ER: A Bayesian method to detect targets of selection in Evolve-and-Resequence experiments. J Evol Biol 2023; 36:29-44. [PMID: 36544394 PMCID: PMC10108205 DOI: 10.1111/jeb.14134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 12/24/2022]
Abstract
For over a decade, experimental evolution has been combined with high-throughput sequencing techniques. In so-called Evolve-and-Resequence (E&R) experiments, populations are kept in the laboratory under controlled experimental conditions where their genomes are sampled and allele frequencies monitored. However, identifying signatures of adaptation in E&R datasets is far from trivial, and it is still necessary to develop more efficient and statistically sound methods for detecting selection in genome-wide data. Here, we present Bait-ER - a fully Bayesian approach based on the Moran model of allele evolution to estimate selection coefficients from E&R experiments. The model has overlapping generations, a feature that describes several experimental designs found in the literature. We tested our method under several different demographic and experimental conditions to assess its accuracy and precision, and it performs well in most scenarios. Nevertheless, some care must be taken when analysing trajectories where drift largely dominates and starting frequencies are low. We compare our method with other available software and report that ours has generally high accuracy even for trajectories whose complexity goes beyond a classical sweep model. Furthermore, our approach avoids the computational burden of simulating an empirical null distribution, outperforming available software in terms of computational time and facilitating its use on genome-wide data. We implemented and released our method in a new open-source software package that can be accessed at https://doi.org/10.5281/zenodo.7351736.
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Affiliation(s)
- Carolina Barata
- Centre for Biological Diversity, University of St Andrews, St Andrews, UK
| | - Rui Borges
- Institute of Population Genetics, Wien, Austria
| | - Carolin Kosiol
- Centre for Biological Diversity, University of St Andrews, St Andrews, UK.,Institute of Population Genetics, Wien, Austria
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36
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Snead AA, Alda F. Time-Series Sequences for Evolutionary Inferences. Integr Comp Biol 2022; 62:1771-1783. [PMID: 36104153 DOI: 10.1093/icb/icac146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 01/05/2023] Open
Affiliation(s)
- Anthony A Snead
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Tuscaloosa, AL 35487, USA
| | - Fernando Alda
- Department of Biology, Geology and Environmental Science, University of Tennessee at Chattanooga, 615 McCallie Ave, Chattanooga, TN 37403, USA
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37
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Snead AA, Clark RD. The Biological Hierarchy, Time, and Temporal 'Omics in Evolutionary Biology: A Perspective. Integr Comp Biol 2022; 62:1872-1886. [PMID: 36057775 DOI: 10.1093/icb/icac138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 01/05/2023] Open
Abstract
Sequencing data-genomics, transcriptomics, epigenomics, proteomics, and metabolomics-have revolutionized biological research, enabling a more detailed study of processes, ranging from subcellular to evolutionary, that drive biological organization. These processes, collectively, are responsible for generating patterns of phenotypic variation and can operate over dramatically different timescales (milliseconds to billions of years). While researchers often study phenotypic variation at specific levels of biological organization to isolate processes operating at that particular scale, the varying types of sequence data, or 'omics, can also provide complementary inferences to link molecular and phenotypic variation to produce an integrated view of evolutionary biology, ranging from molecular pathways to speciation. We briefly describe how 'omics has been used across biological levels and then demonstrate the utility of integrating different types of sequencing data across multiple biological levels within the same study to better understand biological phenomena. However, single-time-point studies cannot evaluate the temporal dynamics of these biological processes. Therefore, we put forward temporal 'omics as a framework that can better enable researchers to study the temporal dynamics of target processes. Temporal 'omics is not infallible, as the temporal sampling regime directly impacts inferential ability. Thus, we also discuss the role the temporal sampling regime plays in deriving inferences about the environmental conditions driving biological processes and provide examples that demonstrate the impact of the sampling regime on biological inference. Finally, we forecast the future of temporal 'omics by highlighting current methodological advancements that will enable temporal 'omics to be extended across species and timescales. We extend this discussion to using temporal multi-omics to integrate across the biological hierarchy to evaluate and link the temporal dynamics of processes that generate phenotypic variation.
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Affiliation(s)
- Anthony A Snead
- Department of Biological Sciences, University of Alabama, 300 Hackberry Lane, Tuscaloosa, AL 35487, USA
| | - René D Clark
- Department of Ecology, Evolution and Natural Resources, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
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38
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Kelly JK. The genomic scale of fluctuating selection in a natural plant population. Evol Lett 2022; 6:506-521. [PMID: 36579169 PMCID: PMC9783439 DOI: 10.1002/evl3.308] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/08/2022] [Accepted: 11/13/2022] [Indexed: 12/30/2022] Open
Abstract
This study characterizes evolution at ≈1.86 million Single Nucleotide Polymorphisms (SNPs) within a natural population of yellow monkeyflower (Mimulus guttatus). Most SNPs exhibit minimal change over a span of 23 generations (less than 1% per year), consistent with neutral evolution in a large population. However, several thousand SNPs display strong fluctuations in frequency. Multiple lines of evidence indicate that these 'Fluctuating SNPs' are driven by temporally varying selection. Unlinked loci exhibit synchronous changes with the same allele increasing consistently in certain time intervals but declining in others. This synchrony is sufficiently pronounced that we can roughly classify intervals into two categories, "green" and "yellow," corresponding to conflicting selection regimes. Alleles increasing in green intervals are associated with early life investment in vegetative tissue and delayed flowering. The alternative alleles that increase in yellow intervals are associated with rapid progression to flowering. Selection on the Fluctuating SNPs produces a strong ripple effect on variation across the genome. Accounting for estimation error, we estimate the distribution of allele frequency change per generation in this population. While change is minimal for most SNPs, diffuse hitchhiking effects generated by selected loci may be driving neutral SNPs to a much greater extent than classic genetic drift.
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Affiliation(s)
- John K. Kelly
- Department of Ecology and Evolutionary BiologyUniversity of KansasLawrenceKansasUSA
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39
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Carrier A, Prunier J, Poisson W, Trottier-Lavoie M, Gilbert I, Cavedon M, Pokharel K, Kantanen J, Musiani M, Côté SD, Albert V, Taillon J, Bourret V, Droit A, Robert C. Design and validation of a 63K genome-wide SNP-genotyping platform for caribou/reindeer (Rangifer tarandus). BMC Genomics 2022; 23:687. [PMID: 36199020 PMCID: PMC9533608 DOI: 10.1186/s12864-022-08899-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Development of large single nucleotide polymorphism (SNP) arrays can make genomic data promptly available for conservation problematic. Medium and high-density panels can be designed with sufficient coverage to offer a genome-wide perspective and the generated genotypes can be used to assess different genetic metrics related to population structure, relatedness, or inbreeding. SNP genotyping could also permit sexing samples with unknown associated metadata as it is often the case when using non-invasive sampling methods favored for endangered species. Genome sequencing of wild species provides the necessary information to design such SNP arrays. We report here the development of a SNP-array for endangered Rangifer tarandus using a multi-platform sequencing approach from animals found in diverse populations representing the entire circumpolar distribution of the species. RESULTS From a very large comprehensive catalog of SNPs detected over the entire sample set (N = 894), a total of 63,336 SNPs were selected. SNP selection accounted for SNPs evenly distributed across the entire genome (~ every 50Kb) with known minor alleles across populations world-wide. In addition, a subset of SNPs was selected to represent rare and local alleles found in Eastern Canada which could be used for ecotype and population assignments - information urgently needed for conservation planning. In addition, heterozygosity from SNPs located in the X-chromosome and genotyping call-rate of SNPs located into the SRY gene of the Y-chromosome yielded an accurate and robust sexing assessment. All SNPs were validated using a high-throughput SNP-genotyping chip. CONCLUSION This design is now integrated into the first genome-wide commercially available genotyping platform for Rangifer tarandus. This platform would pave the way to future genomic investigation of populations for this endangered species, including estimation of genetic diversity parameters, population assignments, as well as animal sexing from genetic SNP data for non-invasive samples.
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Affiliation(s)
- Alexandra Carrier
- Département de sciences animales, Faculté de l'agriculture et d'alimentation, Université Laval, Quebec City, Québec, Canada.,Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Quebec City, Québec, Canada.,Réseau Québécois en reproduction (RQR), Saint-Hyacinthe, Québec, Canada
| | - Julien Prunier
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec City, Québec, Canada
| | - William Poisson
- Département de sciences animales, Faculté de l'agriculture et d'alimentation, Université Laval, Quebec City, Québec, Canada.,Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Quebec City, Québec, Canada.,Réseau Québécois en reproduction (RQR), Saint-Hyacinthe, Québec, Canada
| | - Mallorie Trottier-Lavoie
- Département de sciences animales, Faculté de l'agriculture et d'alimentation, Université Laval, Quebec City, Québec, Canada.,Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Quebec City, Québec, Canada.,Réseau Québécois en reproduction (RQR), Saint-Hyacinthe, Québec, Canada
| | - Isabelle Gilbert
- Département de sciences animales, Faculté de l'agriculture et d'alimentation, Université Laval, Quebec City, Québec, Canada.,Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Quebec City, Québec, Canada.,Réseau Québécois en reproduction (RQR), Saint-Hyacinthe, Québec, Canada
| | - Maria Cavedon
- Department of biological sciences, Faculty of Science, University of Calgary, Calgary, Canada
| | | | - Juha Kantanen
- Natural Resources Institute Finland, Jokioinen, Finland
| | - Marco Musiani
- Department of Biological, Geological and Environmental Sciences (BiGeA), University of Bologna, Bologna, Italy
| | - Steeve D Côté
- Département de biologie - Faculté de sciences et génie, Caribou Ungava, Université Laval, Quebec City, Québec, Canada
| | - Vicky Albert
- Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP), Quebec City, Québec, Canada
| | - Joëlle Taillon
- Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP), Quebec City, Québec, Canada
| | - Vincent Bourret
- Ministère des Forêts, de la Faune et des Parcs du Québec (MFFP), Quebec City, Québec, Canada
| | - Arnaud Droit
- Département de médecine moléculaire, Faculté de médecine, Université Laval, Quebec City, Québec, Canada
| | - Claude Robert
- Département de sciences animales, Faculté de l'agriculture et d'alimentation, Université Laval, Quebec City, Québec, Canada. .,Centre de recherche en reproduction, développement et santé intergénérationnelle (CRDSI), Quebec City, Québec, Canada. .,Réseau Québécois en reproduction (RQR), Saint-Hyacinthe, Québec, Canada.
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40
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Experimental evolution reveals the synergistic genomic mechanisms of adaptation to ocean warming and acidification in a marine copepod. Proc Natl Acad Sci U S A 2022; 119:e2201521119. [PMID: 36095205 PMCID: PMC9499500 DOI: 10.1073/pnas.2201521119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Metazoan adaptation to global change relies on selection of standing genetic variation. Determining the extent to which this variation exists in natural populations, particularly for responses to simultaneous stressors, is essential to make accurate predictions for persistence in future conditions. Here, we identified the genetic variation enabling the copepod Acartia tonsa to adapt to experimental ocean warming, acidification, and combined ocean warming and acidification (OWA) over 25 generations of continual selection. Replicate populations showed a consistent polygenic response to each condition, targeting an array of adaptive mechanisms including cellular homeostasis, development, and stress response. We used a genome-wide covariance approach to partition the allelic changes into three categories: selection, drift and replicate-specific selection, and laboratory adaptation responses. The majority of allele frequency change in warming (57%) and OWA (63%) was driven by shared selection pressures across replicates, but this effect was weaker under acidification alone (20%). OWA and warming shared 37% of their response to selection but OWA and acidification shared just 1%, indicating that warming is the dominant driver of selection in OWA. Despite the dominance of warming, the interaction with acidification was still critical as the OWA selection response was highly synergistic with 47% of the allelic selection response unique from either individual treatment. These results disentangle how genomic targets of selection differ between single and multiple stressors and demonstrate the complexity that nonadditive multiple stressors will contribute to predictions of adaptation to complex environmental shifts caused by global change.
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41
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Busch JW, Bodbyl‐Roels S, Tusuubira S, Kelly JK. Pollinator loss causes rapid adaptive evolution of selfing and dramatically reduces genome-wide genetic variability. Evolution 2022; 76:2130-2144. [PMID: 35852008 PMCID: PMC9543508 DOI: 10.1111/evo.14572] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/23/2022] [Accepted: 04/20/2022] [Indexed: 01/22/2023]
Abstract
Although selfing populations harbor little genetic variation limiting evolutionary potential, the causes are unclear. We experimentally evolved large, replicate populations of Mimulus guttatus for nine generations in greenhouses with or without pollinating bees and studied DNA polymorphism in descendants. Populations without bees adapted to produce more selfed seed yet exhibited striking reductions in DNA polymorphism despite large population sizes. Importantly, the genome-wide pattern of variation cannot be explained by a simple reduction in effective population size, but instead reflects the complicated interaction between selection, linkage, and inbreeding. Simulations demonstrate that the spread of favored alleles at few loci depresses neutral variation genome wide in large populations containing fully selfing lineages. It also generates greater heterogeneity among chromosomes than expected with neutral evolution in small populations. Genome-wide deviations from neutrality were documented in populations with bees, suggesting widespread influences of background selection. After applying outlier tests to detect loci under selection, two genome regions were found in populations with bees, yet no adaptive loci were otherwise mapped. Large amounts of stochastic change in selfing populations compromise evolutionary potential and undermine outlier tests for selection. This occurs because genetic draft in highly selfing populations makes even the largest changes in allele frequency unremarkable.
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Affiliation(s)
- Jeremiah W. Busch
- School of Biological SciencesWashington State UniversityPullmanWashington99164
| | - Sarah Bodbyl‐Roels
- Trefny Innovative Instruction CenterColorado School of MinesGoldenColorado80401
| | - Sharif Tusuubira
- Department of Ecology and Evolutionary BiologyUniversity of KansasLawrenceKansas66045
| | - John K. Kelly
- Department of Ecology and Evolutionary BiologyUniversity of KansasLawrenceKansas66045
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42
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Abstract
Abstract
Few doubt that effective population size (Ne) is one of the most important parameters in evolutionary biology, but how many can say they really understand the concept? Ne is the evolutionary analogue of the number of individuals (or adults) in the population, N. Whereas ecological consequences of population size depend on N, evolutionary consequences (rates of loss of genetic diversity and increase in inbreeding; relative effectiveness of selection) depend on Ne. Formal definitions typically relate effective size to a key population genetic parameter, such as loss of heterozygosity or variance in allele frequency. However, for practical application to real populations, it is more useful to define Ne in terms of three demographic parameters: number of potential parents (adult N), and mean and variance in offspring number. Defined this way, Ne determines the rate of random genetic drift across the entire genome in the offspring generation. Other evolutionary forces (mutation, migration, selection)—together with factors such as variation in recombination rate—can also affect genetic variation, and this leads to heterogeneity across the genome in observed rates of genetic change. For some, it has been convenient to interpret this heterogeneity in terms of heterogeneity in Ne, but unfortunately this has muddled the concepts of genetic drift and effective population size. A commonly-repeated misconception is that Ne is the number of parents that actually contribute genes to the next generation (NP). In reality, NP can be smaller or larger than Ne, and the NP/Ne ratio depends on the sex ratio, the mean and variance in offspring number, and whether inbreeding or variance Ne is of interest.
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Affiliation(s)
- Robin S Waples
- Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA, 98112 USA
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43
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Temperature effects on cellular host-microbe interactions explain continent-wide endosymbiont prevalence. Curr Biol 2022; 32:878-888.e8. [PMID: 34919808 PMCID: PMC8891084 DOI: 10.1016/j.cub.2021.11.065] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/09/2021] [Accepted: 11/26/2021] [Indexed: 01/03/2023]
Abstract
Endosymbioses influence host physiology, reproduction, and fitness, but these relationships require efficient microbe transmission between host generations to persist. Maternally transmitted Wolbachia are the most common known endosymbionts,1 but their frequencies vary widely within and among host populations for unknown reasons.2,3 Here, we integrate genomic, cellular, and phenotypic analyses with mathematical models to provide an unexpectedly simple explanation for global wMel Wolbachia prevalence in Drosophila melanogaster. Cooling temperatures decrease wMel cellular abundance at a key stage of host oogenesis, producing temperature-dependent variation in maternal transmission that plausibly explains latitudinal clines of wMel frequencies on multiple continents. wMel sampled from a temperate climate targets the germline more efficiently in the cold than a recently differentiated tropical variant (∼2,200 years ago), indicative of rapid wMel adaptation to climate. Genomic analyses identify a very narrow list of wMel alleles-most notably, a derived stop codon in the major Wolbachia surface protein WspB-that underlie thermal sensitivity of cellular Wolbachia abundance and covary with temperature globally. Decoupling temperate wMel and host genomes further reduces transmission in the cold, a pattern that is characteristic of host-microbe co-adaptation to a temperate climate. Complex interactions among Wolbachia, hosts, and the environment (GxGxE) mediate wMel cellular abundance and maternal transmission, implicating temperature as a key determinant of Wolbachia spread and equilibrium frequencies, in conjunction with Wolbachia effects on host fitness and reproduction.4,5 Our results motivate the strategic use of locally selected wMel variants for Wolbachia-based biocontrol efforts, which protect millions of individuals from arboviruses that cause human disease.6.
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Saleh D, Chen J, Leplé J, Leroy T, Truffaut L, Dencausse B, Lalanne C, Labadie K, Lesur I, Bert D, Lagane F, Morneau F, Aury J, Plomion C, Lascoux M, Kremer A. Genome-wide evolutionary response of European oaks during the Anthropocene. Evol Lett 2022; 6:4-20. [PMID: 35127134 PMCID: PMC8802238 DOI: 10.1002/evl3.269] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/26/2021] [Accepted: 12/02/2021] [Indexed: 12/23/2022] Open
Abstract
The pace of tree microevolution during Anthropocene warming is largely unknown. We used a retrospective approach to monitor genomic changes in oak trees since the Little Ice Age (LIA). Allelic frequency changes were assessed from whole-genome pooled sequences for four age-structured cohorts of sessile oak (Quercus petraea) dating back to 1680, in each of three different oak forests in France. The genetic covariances of allelic frequency changes increased between successive time periods, highlighting genome-wide effects of linked selection. We found imprints of parallel linked selection in the three forests during the late LIA, and a shift of selection during more recent time periods of the Anthropocene. The changes in allelic covariances within and between forests mirrored the documented changes in the occurrence of extreme events (droughts and frosts) over the last 300 years. The genomic regions with the highest covariances were enriched in genes involved in plant responses to pathogens and abiotic stresses (temperature and drought). These responses are consistent with the reported sequence of frost (or drought) and disease damage ultimately leading to the oak dieback after extreme events. They provide support for adaptive evolution of long-lived species during recent climatic changes. Although we acknowledge that other sources (e.g., gene flow, generation overlap) may have contributed to temporal covariances of allelic frequency changes, the consistent and correlated response across the three forests lends support to the existence of a systematic driving force such as natural selection.
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Affiliation(s)
- Dounia Saleh
- UMR BIOGECO, INRAEUniversité de BordeauxCestas33612France
| | - Jun Chen
- College of Life SciencesZhejiang UniversityHangzhou310058China
| | | | - Thibault Leroy
- Department of Botany and Biodiversity ResearchUniversity of ViennaVienna1010Austria
| | - Laura Truffaut
- UMR BIOGECO, INRAEUniversité de BordeauxCestas33612France
| | | | - Céline Lalanne
- UMR BIOGECO, INRAEUniversité de BordeauxCestas33612France
| | - Karine Labadie
- Genoscope, Institut de Biologie François Jacob, Commissariat à l’énergie atomique (CEA)Université de Paris‐SaclayEvry91057France
| | | | - Didier Bert
- UMR BIOGECO, INRAEUniversité de BordeauxCestas33612France
| | | | - François Morneau
- Département Recherche Développement InnovationOffice National des ForêtsBoigny‐Sur‐Bionne45760France,Current Address: Service de l'Information Statistique Forestière et EnvironnementaleInstitut National de l'Information géographique et ForestièreNogent‐sur‐Vernisson45290France
| | - Jean‐Marc Aury
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRSUniv Evry, Université Paris‐SaclayEvry91057France
| | | | - Martin Lascoux
- Department of Ecology and Genetics, Evolutionary Biology CentreUppsala UniversityUppsalaSE‐75236Sweden
| | - Antoine Kremer
- UMR BIOGECO, INRAEUniversité de BordeauxCestas33612France
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45
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Hayward LK, Sella G. Polygenic adaptation after a sudden change in environment. eLife 2022; 11:66697. [PMID: 36155653 PMCID: PMC9683794 DOI: 10.7554/elife.66697] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Polygenic adaptation is thought to be ubiquitous, yet remains poorly understood. Here, we model this process analytically, in the plausible setting of a highly polygenic, quantitative trait that experiences a sudden shift in the fitness optimum. We show how the mean phenotype changes over time, depending on the effect sizes of loci that contribute to variance in the trait, and characterize the allele dynamics at these loci. Notably, we describe the two phases of the allele dynamics: The first is a rapid phase, in which directional selection introduces small frequency differences between alleles whose effects are aligned with or opposed to the shift, ultimately leading to small differences in their probability of fixation during a second, longer phase, governed by stabilizing selection. As we discuss, key results should hold in more general settings and have important implications for efforts to identify the genetic basis of adaptation in humans and other species.
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Affiliation(s)
- Laura Katharine Hayward
- Department of Mathematics, Columbia UniversityNew YorkUnited States,Institute of Science and TechnologyMaria GuggingAustria
| | - Guy Sella
- Department of Biological Sciences, Columbia UniversityNew YorkUnited States,Program for Mathematical Genomics, Columbia UniversityNew YorkUnited States
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46
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Gene Flow and Genetic Structure Reveal Reduced Diversity between Generations of a Tropical Tree, Manilkara multifida Penn., in Atlantic Forest Fragments. Genes (Basel) 2021; 12:genes12122025. [PMID: 34946973 PMCID: PMC8701937 DOI: 10.3390/genes12122025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/16/2021] [Accepted: 12/03/2021] [Indexed: 12/27/2022] Open
Abstract
The Atlantic Forest remnants in southern Bahia, Brazil, contain large tree species that have suffered disturbances in recent decades. Anthropogenic activities have led to a decrease in the population of many tree species and a loss of alleles that can maintain the evolutionary fitness of their populations. This study assessed patterns of genetic diversity, spatial genetic structure, and genetic structure among Manilkara multifida Penn. populations, comparing the genetic parameters of adult and juvenile trees. In particular, we collected leaves from adults and juveniles of M. multifida in two protected areas, the Veracel Station (EVC) and the Una Biological Reserve (UBR), located in threatened Atlantic Forest fragments. We observed a substantial decay in genetic variability between generations in both areas i.e., adults’ HO values were higher (EVC = 0.720, UBR = 0.736) than juveniles’ (EVC = 0.463 and UBR = 0.560). Both juveniles and adults showed genetic structure between the two areas (θ = 0.017 for adults and θ = 0.109 for juveniles). Additionally, forest fragments indicated an unexpectedly short gene flow. Our results, therefore, highlight the pervasive effects of historical deforestation and other human disturbances on the genetic diversity of M. multifida populations within a key conservation region of the Atlantic Forest biodiversity hotspot.
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47
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Gompert Z, Feder JL, Nosil P. Natural selection drives genome-wide evolution via chance genetic associations. Mol Ecol 2021; 31:467-481. [PMID: 34704650 DOI: 10.1111/mec.16247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/29/2022]
Abstract
Understanding selection's impact on the genome is a major theme in biology. Functionally neutral genetic regions can be affected indirectly by natural selection, via their statistical association with genes under direct selection. The genomic extent of such indirect selection, particularly across loci not physically linked to those under direct selection, remains poorly understood, as does the time scale at which indirect selection occurs. Here, we use field experiments and genomic data in stick insects, deer mice and stickleback fish to show that widespread statistical associations with genes known to affect fitness cause many genetic loci across the genome to be impacted indirectly by selection. This includes regions physically distant from those directly under selection. Then, focusing on the stick insect system, we show that statistical associations between SNPs and other unknown, causal variants result in additional indirect selection in general and specifically within genomic regions of physically linked loci. This widespread indirect selection necessarily makes aspects of evolution more predictable. Thus, natural selection combines with chance genetic associations to affect genome-wide evolution across linked and unlinked loci and even in modest-sized populations. This process has implications for the application of evolutionary principles in basic and applied science.
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Affiliation(s)
- Zachariah Gompert
- Department of Biology, Utah State University, Logan, Utah, USA.,Ecology Center, Utah State University, Logan, Utah, USA
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Patrik Nosil
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, Montpellier, France
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48
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Bertram J. Allele frequency divergence reveals ubiquitous influence of positive selection in Drosophila. PLoS Genet 2021; 17:e1009833. [PMID: 34591854 PMCID: PMC8509871 DOI: 10.1371/journal.pgen.1009833] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 10/12/2021] [Accepted: 09/22/2021] [Indexed: 12/04/2022] Open
Abstract
Resolving the role of natural selection is a basic objective of evolutionary biology. It is generally difficult to detect the influence of selection because ubiquitous non-selective stochastic change in allele frequencies (genetic drift) degrades evidence of selection. As a result, selection scans typically only identify genomic regions that have undergone episodes of intense selection. Yet it seems likely such episodes are the exception; the norm is more likely to involve subtle, concurrent selective changes at a large number of loci. We develop a new theoretical approach that uncovers a previously undocumented genome-wide signature of selection in the collective divergence of allele frequencies over time. Applying our approach to temporally resolved allele frequency measurements from laboratory and wild Drosophila populations, we quantify the selective contribution to allele frequency divergence and find that selection has substantial effects on much of the genome. We further quantify the magnitude of the total selection coefficient (a measure of the combined effects of direct and linked selection) at a typical polymorphic locus, and find this to be large (of order 1%) even though most mutations are not directly under selection. We find that selective allele frequency divergence is substantially elevated at intermediate allele frequencies, which we argue is most parsimoniously explained by positive-not negative-selection. Thus, in these populations most mutations are far from evolving neutrally in the short term (tens of generations), including mutations with neutral fitness effects, and the result cannot be explained simply as an ongoing purging of deleterious mutations.
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Affiliation(s)
- Jason Bertram
- Environmental Resilience Institute, Indiana University, Bloomington, Indiana, United States of America
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
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Johnsson M, Henriksen R, Wright D. The neural crest cell hypothesis: no unified explanation for domestication. Genetics 2021; 219:iyab097. [PMID: 34849908 PMCID: PMC8633120 DOI: 10.1093/genetics/iyab097] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 02/11/2021] [Indexed: 12/03/2022] Open
Affiliation(s)
- Martin Johnsson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala 750 07, Sweden
| | - Rie Henriksen
- IFM Biology, Linköping University, Linköping 58183, Sweden
| | - Dominic Wright
- IFM Biology, Linköping University, Linköping 58183, Sweden
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Buffalo V. Quantifying the relationship between genetic diversity and population size suggests natural selection cannot explain Lewontin's Paradox. eLife 2021; 10:e67509. [PMID: 34409937 PMCID: PMC8486380 DOI: 10.7554/elife.67509] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 08/16/2021] [Indexed: 12/21/2022] Open
Abstract
Neutral theory predicts that genetic diversity increases with population size, yet observed levels of diversity across metazoans vary only two orders of magnitude while population sizes vary over several. This unexpectedly narrow range of diversity is known as Lewontin's Paradox of Variation (1974). While some have suggested selection constrains diversity, tests of this hypothesis seem to fall short. Here, I revisit Lewontin's Paradox to assess whether current models of linked selection are capable of reducing diversity to this extent. To quantify the discrepancy between pairwise diversity and census population sizes across species, I combine previously-published estimates of pairwise diversity from 172 metazoan taxa with newly derived estimates of census sizes. Using phylogenetic comparative methods, I show this relationship is significant accounting for phylogeny, but with high phylogenetic signal and evidence that some lineages experience shifts in the evolutionary rate of diversity deep in the past. Additionally, I find a negative relationship between recombination map length and census size, suggesting abundant species have less recombination and experience greater reductions in diversity due to linked selection. However, I show that even assuming strong and abundant selection, models of linked selection are unlikely to explain the observed relationship between diversity and census sizes across species.
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Affiliation(s)
- Vince Buffalo
- Institute for Ecology and Evolution, University of OregonEugeneUnited States
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