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Aubier TG, Bürger R, Servedio MR. The effectiveness of pseudomagic traits in promoting premating isolation. Proc Biol Sci 2023; 290:20222108. [PMID: 36883275 PMCID: PMC9993058 DOI: 10.1098/rspb.2022.2108] [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: 10/20/2022] [Accepted: 02/10/2023] [Indexed: 03/09/2023] Open
Abstract
Upon the secondary contact of populations, speciation with gene flow is greatly facilitated when the same pleiotropic loci are both subject to divergent ecological selection and induce non-random mating, leading to loci with this fortuitous combination of functions being referred to as 'magic trait' loci. We use a population genetics model to examine whether 'pseudomagic trait' complexes, composed of physically linked loci fulfilling these two functions, are as efficient in promoting premating isolation as magic traits. We specifically measure the evolution of choosiness, which controls the strength of assortative mating. We show that, surprisingly, pseudomagic trait complexes, and to a lesser extent also physically unlinked loci, can lead to the evolution of considerably stronger assortative mating preferences than do magic traits, provided polymorphism at the involved loci is maintained. This is because assortative mating preferences are generally favoured when there is a risk of producing maladapted recombinants, as occurs with non-magic trait complexes but not with magic traits (since pleiotropy precludes recombination). Contrary to current belief, magic traits may not be the most effective genetic architecture for promoting strong premating isolation. Therefore, distinguishing between magic traits and pseudomagic trait complexes is important when inferring their role in premating isolation. This calls for further fine-scale genomic research on speciation genes.
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Affiliation(s)
- Thomas G. Aubier
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Laboratoire Évolution & Diversité Biologique, Université Paul Sabatier Toulouse III, UMR 5174, CNRS/IRD, 31077 Toulouse, France
| | - Reinhard Bürger
- Department of Mathematics, University of Vienna, 1090 Vienna, Austria
| | - Maria R. Servedio
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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2
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Sibly RM, Curnow RN. Sexual imprinting leads to speciation in locally adapted populations. Ecol Evol 2022; 12:e9479. [DOI: 10.1002/ece3.9479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
| | - Robert N. Curnow
- Department of Mathematics and Statistics University of Reading Reading UK
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3
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Clark JD, Benham PM, Maldonado JE, Luther DA, Lim HC. Maintenance of local adaptation despite gene flow in a coastal songbird. Evolution 2022; 76:1481-1494. [PMID: 35700208 PMCID: PMC9545442 DOI: 10.1111/evo.14538] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/09/2022] [Accepted: 03/19/2022] [Indexed: 01/22/2023]
Abstract
Adaptation to local environments is common in widespread species and the basis of ecological speciation. The song sparrow (Melospiza melodia) is a widespread, polytypic passerine that occurs in shrubland habitats throughout North America. We examined the population structure of two parapatric subspecies that inhabit different environments: the Atlantic song sparrow (M. m. atlantica), a coastal specialist, and the eastern song sparrow (M. m. melodia), a shrubland generalist. These populations lacked clear mitochondrial population structure, yet coastal birds formed a distinct nuclear genetic cluster. We found weak overall genomic differentiation between these subspecies, suggesting either recent divergence, extensive gene flow, or a combination thereof. There was a steep genetic cline at the transition to coastal habitats, consistent with isolation by environment, not isolation by distance. A phenotype under divergent selection, bill size, varied with the amount of coastal ancestry in transitional areas, but larger bill size was maintained in coastal habitats regardless of ancestry, further supporting a role for selection in the maintenance of these subspecies. Demographic modeling suggested a divergence history of limited gene flow followed by secondary contact, which has emerged as a common theme in adaptive divergence across taxa.
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Affiliation(s)
- Jonathan D. Clark
- Department of Environmental Science and PolicyGeorge Mason UniversityFairfaxVirginia22030,Current Address: Department of Natural Resources and the EnvironmentUniversity of New HampshireDurhamNew Hampshire03824
| | - Phred M. Benham
- Museum of Vertebrate ZoologyUniversity of California, BerkeleyBerkeleyCalifornia94720
| | - Jesus E. Maldonado
- Department of Environmental Science and PolicyGeorge Mason UniversityFairfaxVirginia22030,Center for Conservation GenomicsSmithsonian Conservation Biology InstituteWashingtonD.C.20013
| | - David A. Luther
- Department of BiologyGeorge Mason UniversityFairfaxVirginia22030
| | - Haw Chuan Lim
- Center for Conservation GenomicsSmithsonian Conservation Biology InstituteWashingtonD.C.20013,Department of BiologyGeorge Mason UniversityFairfaxVirginia22030
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Cotto O, Servedio MR, Day T. The evolution of age-specific choosiness and reproductive isolation in a model with overlapping generations. Evolution 2021; 76:225-235. [PMID: 34877658 DOI: 10.1111/evo.14417] [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: 10/22/2020] [Accepted: 10/31/2021] [Indexed: 11/30/2022]
Abstract
The strength of mate choice (choosiness) often varies with age, but theory to understand this variation is scarce. Additionally, theory has investigated the evolution of choosiness in speciation scenarios but has ignored that most organisms have overlapping generations. We investigate whether speciation can result in variation of choosiness with age, and whether such variation can in turn affect speciation. We develop a population-genetic model of the evolution of choosiness in organisms with overlapping generations in the context of secondary contact between two divergent populations. We assume that females choose males that match their phenotype, such that choosiness evolves by sexual selection. We demonstrate that speciation can result in the evolution of age-specific choosiness when the mating trait is under divergent ecological selection and age is not used as a mating cue. The cause of this result is that allele frequencies differ between choosy females and males. However, we find that the evolution of age-specific choosiness does not affect the overall level of reproductive isolation compared to a case without age-structure, supporting previous speciation theory. Overall, our results connect life history and speciation theory, and the mechanisms that we highlight have implications for the understanding of the role of sex-specific selection in the evolution of choosiness.
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Affiliation(s)
- Olivier Cotto
- Departments of Mathematics and Statistics, Department of Biology, Queens University, Kingston, Ontario, Canada.,Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, Université PSL, Paris, France
| | - Maria R Servedio
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, 27599, United States
| | - Troy Day
- Departments of Mathematics and Statistics, Department of Biology, Queens University, Kingston, Ontario, Canada
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McCulloch GA, Guhlin J, Dutoit L, Harrop TWR, Dearden PK, Waters JM. Genomic signatures of parallel alpine adaptation in recently evolved flightless insects. Mol Ecol 2021; 30:6677-6686. [PMID: 34592029 DOI: 10.1111/mec.16204] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/16/2021] [Accepted: 09/27/2021] [Indexed: 12/01/2022]
Abstract
Natural selection along elevational gradients has potential to drive predictable adaptations across distinct lineages, but the extent of such repeated evolution remains poorly studied for many widespread alpine taxa. We present parallel genomic analyses of two recently evolved flightless alpine insect lineages to test for molecular signatures of repeated alpine adaptation. Specifically, we compare low-elevation vs. alpine stonefly ecotypes from parallel stream populations in which flightless upland ecotypes have been independently derived. We map 67,922 polymorphic genetic markers, generated across 176 Zelandoperla fenestrata specimens from two independent alpine stream populations in New Zealand's Rock and Pillar Range, to a newly developed plecopteran reference genome. Genome-wide scans revealed 31 regions with outlier single nucleotide polymorphisms (SNPs) differentiating lowland vs. alpine ecotypes in Lug Creek, and 37 regions with outliers differentiating ecotypes in Six Mile Creek. Of these regions, 13% (8/60) yielded outlier SNPs across both within-stream ecotype comparisons, implying comparable genomic shifts contribute to this repeated alpine adaptation. Candidate genes closely linked to repeated outlier regions include several with documented roles in insect wing-development (e.g., dishevelled), suggesting that they may contribute to repeated alpine wing reduction. Additional candidate genes have been shown to influence insect fecundity (e.g., ovo) and lifespan (e.g., Mrp4), implying that they might contribute to life history differentiation between upland and lowland ecotypes. Additional outlier genes have potential roles in the evolution of reproductive isolation among ecotypes (hedgehog and Desaturase 1). These results demonstrate how replicated outlier tests across independent lineages can potentially contribute to the discovery of genes underpinning repeated adaptation.
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Affiliation(s)
| | - Joseph Guhlin
- Genomics Aotearoa and Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Ludovic Dutoit
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Thomas W R Harrop
- Genomics Aotearoa and Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Peter K Dearden
- Genomics Aotearoa and Department of Biochemistry, University of Otago, Dunedin, New Zealand
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The importance of species interactions in eco-evolutionary community dynamics under climate change. Nat Commun 2021; 12:4759. [PMID: 34362916 PMCID: PMC8346578 DOI: 10.1038/s41467-021-24977-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/14/2021] [Indexed: 02/07/2023] Open
Abstract
Eco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species' interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.
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Estandia A, Sendell-Price AT. Digest: The role of linkage in mimicking "magic traits". Evolution 2020; 74:2539-2540. [PMID: 32970330 DOI: 10.1111/evo.14102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/21/2020] [Indexed: 01/31/2023]
Abstract
Can divergence in a mating trait increase local adaption by increasing ecological divergence? Servedio and Bürger propose that "pseudomagic traits," tightly linked complexes consisting of an ecological locus under divergent selection and a locus acting as a mating cue, can effectively mimic pleiotropy. Such pseudomagic traits can form even when linkage between ecological and mating loci is limited.
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Affiliation(s)
- Andrea Estandia
- Department of Zoology, University of Oxford, Oxford, United Kingdom
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