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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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2
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Villoutreix R, de Carvalho CF, Feder JL, Gompert Z, Nosil P. Disruptive selection and the evolution of discrete color morphs in Timema stick insects. SCIENCE ADVANCES 2023; 9:eabm8157. [PMID: 37000882 PMCID: PMC10065444 DOI: 10.1126/sciadv.abm8157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/27/2023] [Indexed: 06/19/2023]
Abstract
A major unresolved issue in biology is why phenotypic and genetic variation is sometimes continuous, yet other times packaged into discrete units of diversity, such as morphs, ecotypes, and species. In theory, ecological discontinuities can impose strong disruptive selection that promotes the evolution of discrete forms, but direct tests of this hypothesis are lacking. Here, we show that Timema stick insects exhibit genetically determined color morphs that range from weakly to strongly discontinuous. Color data from nature and a manipulative field experiment demonstrate that greater morph differentiation is associated with shifts from host plants exhibiting more continuous color variation to those exhibiting greater coloration distance between green leaves and brown stems, the latter of which generates strong disruptive selection. Our results show how ecological factors can promote discrete variation, and we further present results on how this can have variable effects on the genetic differentiation that promotes speciation.
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Affiliation(s)
| | - Clarissa F. de Carvalho
- CEFE, Université Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Departamento de Ecologia e Biologia Evolutiva, UNIFESP, Diadema 09972-270, Brazil
| | - Jeffrey L. Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | | | - Patrik Nosil
- CEFE, Université Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Department of Biology, Utah State University, Logan, UT 84322, USA
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3
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Chaturvedi S, Gompert Z, Feder JL, Osborne OG, Muschick M, Riesch R, Soria-Carrasco V, Nosil P. Climatic similarity and genomic background shape the extent of parallel adaptation in Timema stick insects. Nat Ecol Evol 2022; 6:1952-1964. [PMID: 36280782 PMCID: PMC7613875 DOI: 10.1038/s41559-022-01909-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 09/13/2022] [Indexed: 12/15/2022]
Abstract
Evolution can repeat itself, resulting in parallel adaptations in independent lineages occupying similar environments. Moreover, parallel evolution sometimes, but not always, uses the same genes. Two main hypotheses have been put forth to explain the probability and extent of parallel evolution. First, parallel evolution is more likely when shared ecologies result in similar patterns of natural selection in different taxa. Second, parallelism is more likely when genomes are similar because of shared standing variation and similar mutational effects in closely related genomes. Here we combine ecological, genomic, experimental and phenotypic data with Bayesian modelling and randomization tests to quantify the degree of parallelism and its relationship with ecology and genetics. Our results show that the extent to which genomic regions associated with climate are parallel among species of Timema stick insects is shaped collectively by shared ecology and genomic background. Specifically, the extent of genomic parallelism decays with divergence in climatic conditions (that is, habitat or ecological similarity) and genomic similarity. Moreover, we find that climate-associated loci are likely subject to selection in a field experiment, overlap with genetic regions associated with cuticular hydrocarbon traits and are not strongly shaped by introgression between species. Our findings shed light on when evolution is most expected to repeat itself.
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Affiliation(s)
- Samridhi Chaturvedi
- Department of Integrative Biology, University of California, Berkeley, CA, USA.
- Department of Biology and Ecology Center, Utah State University, Logan, UT, USA.
| | - Zachariah Gompert
- Department of Biology and Ecology Center, Utah State University, Logan, UT, USA.
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Owen G Osborne
- Molecular Ecology and Evolution Bangor, Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, UK
| | - Moritz Muschick
- Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute for Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Rüdiger Riesch
- Department of Biological Sciences, Royal Holloway University of London, Egham, UK
| | | | - Patrik Nosil
- Department of Biology and Ecology Center, Utah State University, Logan, UT, USA
- CEFE, Univ. Montpellier, CNRS, EPHE, IRD, Univ. Paul Valéry Montpellier 3, Montpellier, France
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4
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Arnqvist G, Sayadi A. A possible genomic footprint of polygenic adaptation on population divergence in seed beetles? Ecol Evol 2022; 12:e9440. [PMID: 36311399 PMCID: PMC9608792 DOI: 10.1002/ece3.9440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 09/14/2022] [Accepted: 09/29/2022] [Indexed: 11/25/2022] Open
Abstract
Efforts to unravel the genomic basis of incipient speciation are hampered by a mismatch between our toolkit and our understanding of the ecology and genetics of adaptation. While the former is focused on detecting selective sweeps involving few independently acting or linked speciation genes, the latter states that divergence typically occurs in polygenic traits under stabilizing selection. Here, we ask whether a role of stabilizing selection on polygenic traits in population divergence may be unveiled by using a phenotypically informed integrative approach, based on genome‐wide variation segregating in divergent populations. We compare three divergent populations of seed beetles (Callosobruchus maculatus) where previous work has demonstrated a prominent role for stabilizing selection on, and population divergence in, key life history traits that reflect rate‐dependent metabolic processes. We derive and assess predictions regarding the expected pattern of covariation between genetic variation segregating within populations and genetic differentiation between populations. Population differentiation was considerable (mean FST = 0.23–0.26) and was primarily built by genes showing high selective constraints and an imbalance in inferred selection in different populations (positive Tajima's DNS in one and negative in one), and this set of genes was enriched with genes with a metabolic function. Repeatability of relative population differentiation was low at the level of individual genes but higher at the level of broad functional classes, again spotlighting metabolic genes. Absolute differentiation (dXY) showed a very different general pattern at this scale of divergence, more consistent with an important role for genetic drift. Although our exploration is consistent with stabilizing selection on polygenic metabolic phenotypes as an important engine of genome‐wide relative population divergence and incipient speciation in our study system, we note that it is exceedingly difficult to firmly exclude other scenarios.
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Affiliation(s)
- Göran Arnqvist
- Animal Ecology, Department of Ecology and Genetics, EBCUppsala UniversityUppsalaSweden
| | - Ahmed Sayadi
- Animal Ecology, Department of Ecology and Genetics, EBCUppsala UniversityUppsalaSweden,Rheumatology, Department of Medical SciencesUppsala UniversityUppsalaSweden
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5
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Villoutreix R, de Carvalho CF, Gompert Z, Parchman TL, Feder JL, Nosil P. Testing for fitness epistasis in a transplant experiment identifies a candidate adaptive locus in Timema stick insects. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200508. [PMID: 35634927 PMCID: PMC9149791 DOI: 10.1098/rstb.2020.0508] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 12/18/2021] [Indexed: 07/20/2023] Open
Abstract
Identifying the genetic basis of adaptation is a central goal of evolutionary biology. However, identifying genes and mutations affecting fitness remains challenging because a large number of traits and variants can influence fitness. Selected phenotypes can also be difficult to know a priori, complicating top-down genetic approaches for trait mapping that involve crosses or genome-wide association studies. In such cases, experimental genetic approaches, where one maps fitness directly and attempts to infer the traits involved afterwards, can be valuable. Here, we re-analyse data from a transplant experiment involving Timema stick insects, where five physically clustered single-nucleotide polymorphisms associated with cryptic body coloration were shown to interact to affect survival. Our analysis covers a larger genomic region than past work and revealed a locus previously not identified as associated with survival. This locus resides near a gene, Punch (Pu), involved in pteridine pigments production, implying that it could be associated with an unmeasured coloration trait. However, by combining previous and newly obtained phenotypic data, we show that this trait is not eye or body coloration. We discuss the implications of our results for the discovery of traits, genes and mutations associated with fitness in other systems, as well as for supergene evolution. This article is part of the theme issue 'Genetic basis of adaptation and speciation: from loci to causative mutations'.
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Affiliation(s)
- Romain Villoutreix
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, Montpellier 34293, France
| | | | | | | | - Jeffrey L. Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Patrik Nosil
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, Montpellier 34293, France
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6
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A method to predict the response to directional selection using a Kalman filter. Proc Natl Acad Sci U S A 2022; 119:e2117916119. [PMID: 35867739 DOI: 10.1073/pnas.2117916119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Predicting evolution remains challenging. The field of quantitative genetics provides predictions for the response to directional selection through the breeder's equation, but these predictions can have errors. The sources of these errors include omission of traits under selection, inaccurate estimates of genetic variance, and nonlinearities in the relationship between genetic and phenotypic variation. Previous research showed that the expected value of these prediction errors is often not zero, so predictions are systematically biased. Here, we propose that this bias, rather than being a nuisance, can be used to improve the predictions. We use this to develop a method to predict evolution, which is built on three key innovations. First, the method predicts change as the breeder's equation plus a bias term. Second, the method combines information from the breeder's equation and from the record of past changes in the mean to predict change using a Kalman filter. Third, the parameters of the filter are fitted in each generation using a learning algorithm on the record of past changes. We compare the method to the breeder's equation in two artificial selection experiments, one using the wing of the fruit fly and another using simulations that include a complex mapping of genotypes to phenotypes. The proposed method outperforms the breeder's equation, particularly when traits under selection are omitted from the analysis, when data are noisy, and when additive genetic variance is estimated inaccurately or not estimated at all. The proposed method is easy to apply, requiring only the trait means over past generations.
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7
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Patton AH, Richards EJ, Gould KJ, Buie LK, Martin CH. Hybridization alters the shape of the genotypic fitness landscape, increasing access to novel fitness peaks during adaptive radiation. eLife 2022; 11:e72905. [PMID: 35616528 PMCID: PMC9135402 DOI: 10.7554/elife.72905] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 04/14/2022] [Indexed: 12/30/2022] Open
Abstract
Estimating the complex relationship between fitness and genotype or phenotype (i.e. the adaptive landscape) is one of the central goals of evolutionary biology. However, adaptive walks connecting genotypes to organismal fitness, speciation, and novel ecological niches are still poorly understood and processes for surmounting fitness valleys remain controversial. One outstanding system for addressing these connections is a recent adaptive radiation of ecologically and morphologically novel pupfishes (a generalist, molluscivore, and scale-eater) endemic to San Salvador Island, Bahamas. We leveraged whole-genome sequencing of 139 hybrids from two independent field fitness experiments to identify the genomic basis of fitness, estimate genotypic fitness networks, and measure the accessibility of adaptive walks on the fitness landscape. We identified 132 single nucleotide polymorphisms (SNPs) that were significantly associated with fitness in field enclosures. Six out of the 13 regions most strongly associated with fitness contained differentially expressed genes and fixed SNPs between trophic specialists; one gene (mettl21e) was also misexpressed in lab-reared hybrids, suggesting a potential intrinsic genetic incompatibility. We then constructed genotypic fitness networks from adaptive alleles and show that scale-eating specialists are the most isolated of the three species on these networks. Intriguingly, introgressed and de novo variants reduced fitness landscape ruggedness as compared to standing variation, increasing the accessibility of genotypic fitness paths from generalist to specialists. Our results suggest that adaptive introgression and de novo mutations alter the shape of the fitness landscape, providing key connections in adaptive walks circumventing fitness valleys and triggering the evolution of novelty during adaptive radiation.
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Affiliation(s)
- Austin H Patton
- Department of Integrative Biology, University of California, BerkeleyBerkeleyUnited States
- Museum of Vertebrate Zoology, University of California, BerkeleyBerkeleyUnited States
| | - Emilie J Richards
- Department of Integrative Biology, University of California, BerkeleyBerkeleyUnited States
- Museum of Vertebrate Zoology, University of California, BerkeleyBerkeleyUnited States
| | - Katelyn J Gould
- Department of Biology, University of North CarolinaChapel HillUnited States
| | - Logan K Buie
- Department of Biology, University of North CarolinaChapel HillUnited States
| | - Christopher H Martin
- Department of Integrative Biology, University of California, BerkeleyBerkeleyUnited States
- Museum of Vertebrate Zoology, University of California, BerkeleyBerkeleyUnited States
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8
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Thompson KA, Schluter D. Heterosis counteracts hybrid breakdown to forestall speciation by parallel natural selection. Proc Biol Sci 2022; 289:20220422. [PMID: 35506223 PMCID: PMC9065978 DOI: 10.1098/rspb.2022.0422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In contrast to ecological speciation, where reproductive isolation evolves as a consequence of divergent natural selection, speciation by parallel natural selection has been less thoroughly studied. To test whether parallel evolution drives speciation, we leveraged the repeated evolution of benthic and limnetic ecotypes of threespine stickleback fish and estimated fitness for pure crosses and within-ecotype hybrids in semi-natural ponds and in laboratory aquaria. In ponds, we detected hybrid breakdown in both ecotypes but this was counterbalanced by heterosis and the strength of post-zygotic isolation was nil. In aquaria, we detected heterosis in limnetic crosses and breakdown in benthic crosses, which is suggestive of process- and ecotype-specific environment-dependence. In ponds, heterosis and breakdown were three times greater in limnetic crosses than in benthic crosses, contrasting the prediction that the fitness consequences of hybridization should be greater in crosses among more derived ecotypes. Consistent with a primary role for stochastic processes, patterns differed among crosses between populations from different lakes. Yet, the observation of qualitatively similar patterns of heterosis and hybrid breakdown for both ecotypes when averaging the lake pairs indicates that the outcome of hybridization is repeatable in a general sense.
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Affiliation(s)
- Ken A. Thompson
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dolph Schluter
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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9
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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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10
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Nosil P, Feder JL, Gompert Z. Biodiversity, resilience and the stability of evolutionary systems. Curr Biol 2021; 31:R1149-R1153. [PMID: 34637720 DOI: 10.1016/j.cub.2021.01.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Various macro-evolutionary phenomena, such as long-term stability punctuated by bursts of evolution, are difficult to explain via the micro-evolutionary process of weak selection acting steadily on individual mutations. In contrast, bursts of change are expected if evolutionary systems are complex and balanced, with occasional disruption of balance. Such disruption represents the collapse of resilience, akin to the snapping of an elastic band. It can be driven by external factors, or by self-propagating feedback loops internal to a system. Thus, evolutionary resilience could help explain how evolution generates broader patterns of biodiversity. We outline evidence and tests for this hypothesis, which emphasizes the processes balancing evolution, as urged fifty years ago in ecological genetics and via modern results in a range of systems.
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Affiliation(s)
- Patrik Nosil
- CEFE, Univ. Montpellier, CNRS, EPHE, IRD, Univ Paul Valery Montpellier 3, Montpellier, 34293, France; Department of Biology, Utah State University, Logan, UT 84322, USA.
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
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11
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Messina FJ, Lish AM, Gompert Z. Disparate genetic variants associated with distinct components of cowpea resistance to the seed beetle Callosobruchus maculatus. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2021; 134:2749-2766. [PMID: 34117909 DOI: 10.1007/s00122-021-03856-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/08/2021] [Indexed: 06/12/2023]
Abstract
Polygenic genome-wide association mapping identified two regions of the cowpea genome associated with different components of resistance to its major post-harvest pest, the seed beetle Callosobruchus maculatus. Cowpea (Vigna unguiculata) is an important grain and fodder crop in arid and semi-arid regions of Africa, Asia, and South America, where the cowpea seed beetle, Callosobruchus maculatus, is a serious post-harvest pest. Development of cultivars resistant to C. maculatus population growth in storage could increase grain yield and quality and reduce reliance on insecticides. Here, we use a MAGIC (multi-parent, advanced-generation intercross) population of cowpea consisting of 305 recombinant inbred lines (RILs) to identify genetic variants associated with resistance to seed beetles. Because inferences regarding the genetic basis of resistance may depend on the source of the pest or the assay protocol, we used two divergent geographic populations of C. maculatus and two complementary assays to measure several aspects of resistance. Using polygenic genome-wide association mapping models, we found that the cowpea RILs harbor substantial additive-genetic variation for most resistance measures. Variation in several components of resistance, including larval development time and survival, was largely explained by one or several linked loci on chromosome 5. A second region on chromosome 8 explained increased seed resistance via the induction of early-exiting larvae. Neither of these regions contained genes previously associated with resistance to insects that infest grain legumes. We found some evidence of gene-gene interactions affecting resistance, but epistasis did not contribute substantially to resistance variation in this mapping population. The combination of mostly high heritabilities and a relatively consistent and simple genetic architecture increases the feasibility of breeding for enhanced resistance to C. maculatus.
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Affiliation(s)
- Frank J Messina
- Department of Biology, Utah State University, Logan, UT, 84322, USA
| | - Alexandra M Lish
- Department of Biology, Utah State University, Logan, UT, 84322, USA
| | - Zachariah Gompert
- Department of Biology, Utah State University, Logan, UT, 84322, USA.
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12
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Morrison AJ, Wonderlick DR, Harms MJ. Ensemble epistasis: thermodynamic origins of nonadditivity between mutations. Genetics 2021; 219:iyab105. [PMID: 34849909 PMCID: PMC8633102 DOI: 10.1093/genetics/iyab105] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/19/2021] [Indexed: 01/02/2023] Open
Abstract
Epistasis-when mutations combine nonadditively-is a profoundly important aspect of biology. It is often difficult to understand its mechanistic origins. Here, we show that epistasis can arise from the thermodynamic ensemble, or the set of interchanging conformations a protein adopts. Ensemble epistasis occurs because mutations can have different effects on different conformations of the same protein, leading to nonadditive effects on its average, observable properties. Using a simple analytical model, we found that ensemble epistasis arises when two conditions are met: (1) a protein populates at least three conformations and (2) mutations have differential effects on at least two conformations. To explore the relative magnitude of ensemble epistasis, we performed a virtual deep-mutational scan of the allosteric Ca2+ signaling protein S100A4. We found that 47% of mutation pairs exhibited ensemble epistasis with a magnitude on the order of thermal fluctuations. We observed many forms of epistasis: magnitude, sign, and reciprocal sign epistasis. The same mutation pair could even exhibit different forms of epistasis under different environmental conditions. The ubiquity of thermodynamic ensembles in biology and the pervasiveness of ensemble epistasis in our dataset suggests that it may be a common mechanism of epistasis in proteins and other macromolecules.
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Affiliation(s)
- Anneliese J Morrison
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene OR 97403, USA
| | - Daria R Wonderlick
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene OR 97403, USA
| | - Michael J Harms
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
- Department of Chemistry and Biochemistry, University of Oregon, Eugene OR 97403, USA
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13
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Machado HE, Bergland AO, Taylor R, Tilk S, Behrman E, Dyer K, Fabian DK, Flatt T, González J, Karasov TL, Kim B, Kozeretska I, Lazzaro BP, Merritt TJS, Pool JE, O'Brien K, Rajpurohit S, Roy PR, Schaeffer SW, Serga S, Schmidt P, Petrov DA. Broad geographic sampling reveals the shared basis and environmental correlates of seasonal adaptation in Drosophila. eLife 2021; 10:e67577. [PMID: 34155971 PMCID: PMC8248982 DOI: 10.7554/elife.67577] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/21/2021] [Indexed: 11/16/2022] Open
Abstract
To advance our understanding of adaptation to temporally varying selection pressures, we identified signatures of seasonal adaptation occurring in parallel among Drosophila melanogaster populations. Specifically, we estimated allele frequencies genome-wide from flies sampled early and late in the growing season from 20 widely dispersed populations. We identified parallel seasonal allele frequency shifts across North America and Europe, demonstrating that seasonal adaptation is a general phenomenon of temperate fly populations. Seasonally fluctuating polymorphisms are enriched in large chromosomal inversions, and we find a broad concordance between seasonal and spatial allele frequency change. The direction of allele frequency change at seasonally variable polymorphisms can be predicted by weather conditions in the weeks prior to sampling, linking the environment and the genomic response to selection. Our results suggest that fluctuating selection is an important evolutionary force affecting patterns of genetic variation in Drosophila.
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Affiliation(s)
- Heather E Machado
- Department of Biology, Stanford UniversityStanfordUnited States
- Wellcome Sanger InstituteHinxtonUnited Kingdom
| | - Alan O Bergland
- Department of Biology, Stanford UniversityStanfordUnited States
- Department of Biology, University of VirginiaCharlottesvilleUnited States
| | - Ryan Taylor
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Susanne Tilk
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Emily Behrman
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Kelly Dyer
- Department of Genetics, University of GeorgiaAthensUnited States
| | - Daniel K Fabian
- Institute of Population Genetics, Vetmeduni ViennaViennaAustria
- Centre for Pathogen Evolution, Department of Zoology, University of CambridgeCambridgeUnited Kingdom
| | - Thomas Flatt
- Institute of Population Genetics, Vetmeduni ViennaViennaAustria
- Department of Biology, University of FribourgFribourgSwitzerland
| | - Josefa González
- Institute of Evolutionary Biology, CSIC- Universitat Pompeu FabraBarcelonaSpain
| | - Talia L Karasov
- Department of Biology, University of UtahSalt Lake CityUnited States
| | - Bernard Kim
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Iryna Kozeretska
- Taras Shevchenko National University of KyivKyivUkraine
- National Antarctic Scientific Centre of Ukraine, Taras Shevchenko Blvd.KyivUkraine
| | - Brian P Lazzaro
- Department of Entomology, Cornell UniversityIthacaUnited States
| | - Thomas JS Merritt
- Department of Chemistry & Biochemistry, Laurentian UniversitySudburyCanada
| | - John E Pool
- Laboratory of Genetics, University of Wisconsin-MadisonMadisonUnited States
| | - Katherine O'Brien
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Subhash Rajpurohit
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Paula R Roy
- Department of Ecology and Evolutionary Biology, University of KansasLawrenceUnited States
| | - Stephen W Schaeffer
- Department of Biology, The Pennsylvania State UniversityUniversity ParkUnited States
| | - Svitlana Serga
- Taras Shevchenko National University of KyivKyivUkraine
- National Antarctic Scientific Centre of Ukraine, Taras Shevchenko Blvd.KyivUkraine
| | - Paul Schmidt
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Dmitri A Petrov
- Department of Biology, Stanford UniversityStanfordUnited States
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14
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Correlational selection in the age of genomics. Nat Ecol Evol 2021; 5:562-573. [PMID: 33859374 DOI: 10.1038/s41559-021-01413-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/11/2021] [Indexed: 02/01/2023]
Abstract
Ecologists and evolutionary biologists are well aware that natural and sexual selection do not operate on traits in isolation, but instead act on combinations of traits. This long-recognized and pervasive phenomenon is known as multivariate selection, or-in the particular case where it favours correlations between interacting traits-correlational selection. Despite broad acknowledgement of correlational selection, the relevant theory has often been overlooked in genomic research. Here, we discuss theory and empirical findings from ecological, quantitative genetic and genomic research, linking key insights from different fields. Correlational selection can operate on both discrete trait combinations and quantitative characters, with profound implications for genomic architecture, linkage, pleiotropy, evolvability, modularity, phenotypic integration and phenotypic plasticity. We synthesize current knowledge and discuss promising research approaches that will enable us to understand how correlational selection shapes genomic architecture, thereby linking quantitative genetic approaches with emerging genomic methods. We suggest that research on correlational selection has great potential to integrate multiple fields in evolutionary biology, including developmental and functional biology, ecology, quantitative genetics, phenotypic polymorphisms, hybrid zones and speciation processes.
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Increasing our ability to predict contemporary evolution. Nat Commun 2020; 11:5592. [PMID: 33154385 PMCID: PMC7645684 DOI: 10.1038/s41467-020-19437-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 10/15/2020] [Indexed: 12/21/2022] Open
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