1
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Long KM, Rivera-Colón AG, Bennett KFP, Catchen JM, Braun MJ, Brawn JD. Ongoing introgression of a secondary sexual plumage trait in a stable avian hybrid zone. Evolution 2024; 78:1539-1553. [PMID: 38753474 DOI: 10.1093/evolut/qpae076] [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: 04/03/2023] [Accepted: 05/14/2024] [Indexed: 05/18/2024]
Abstract
Hybrid zones are dynamic systems where natural selection, sexual selection, and other evolutionary forces can act on reshuffled combinations of distinct genomes. The movement of hybrid zones, individual traits, or both are of particular interest for understanding the interplay between selective processes. In a hybrid zone involving two lek-breeding birds, secondary sexual plumage traits of Manacus vitellinus, including bright yellow collar and olive belly color, have introgressed ~50 km asymmetrically across the genomic center of the zone into populations more genetically similar to Manacus candei. Males with yellow collars are preferred by females and are more aggressive than parental M. candei, suggesting that sexual selection was responsible for the introgression of male traits. We assessed the spatial and temporal dynamics of this hybrid zone using historical (1989-1994) and contemporary (2017-2020) transect samples to survey both morphological and genetic variation. Genome-wide single nucleotide polymorphism data and several male phenotypic traits show that the genomic center of the zone has remained spatially stable, whereas the olive belly color of male M. vitellinus has continued to introgress over this time period. Our data suggest that sexual selection can continue to shape phenotypes dynamically, independent of a stable genomic transition between species.
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Affiliation(s)
- Kira M Long
- Program in Ecology, Evolution and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID, United States
| | - Angel G Rivera-Colón
- Department of Evolution, Ecology, and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Kevin F P Bennett
- Behavior, Ecology, Evolution, and Systematics Program, University of Maryland, College Park, MD, United States
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States
| | - Julian M Catchen
- Department of Evolution, Ecology, and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Michael J Braun
- Behavior, Ecology, Evolution, and Systematics Program, University of Maryland, College Park, MD, United States
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States
| | - Jeffrey D Brawn
- Department of Natural Resources & Environmental Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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2
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Massey DJ, Szpiech ZA, Goldberg A. Differentiating mechanism from outcome for ancestry-assortative mating in admixed human populations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.06.597727. [PMID: 38895317 PMCID: PMC11185628 DOI: 10.1101/2024.06.06.597727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Population genetic theory, and the empirical methods built upon it, often assume that individuals pair randomly for reproduction. However, natural populations frequently violate this assumption, which may potentially confound genome-wide association studies, selection scans, and demographic inference. Within several recently admixed human populations, empirical genetic studies have reported a correlation in global ancestry proportion between spouses, referred to as ancestry-assortative mating. Here, we use forward genomic simulations to link correlations in ancestry between mates to the underlying mechanistic mate-choice process. We consider the impacts of two types of mate-choice model, using either ancestry-based preferences or social groups as the basis for mate pairing. We find that multiple mate-choice models can produce the same correlations in ancestry proportion between spouses; however, we also highlight alternative analytic approaches and circumstances in which these models may be distinguished. With this work, we seek to highlight potential pitfalls when interpreting correlations in empirical data as evidence for a particular model of human mating practices, as well as to offer suggestions toward development of new best practices for analysis of human ancestry-assortative mating.
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Affiliation(s)
| | - Zachary A Szpiech
- Department of Biology, Pennsylvania State University, USA 16801
- Institute for Computational and Data Sciences, Pennsylvania State University, USA 16801
| | - Amy Goldberg
- Department of Evolutionary Anthropology, Duke University, USA 27708
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3
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McFarlane SE, Jahner JP, Lindtke D, Buerkle CA, Mandeville EG. Selection leads to remarkable variability in the outcomes of hybridisation across replicate hybrid zones. Mol Ecol 2024; 33:e17359. [PMID: 38699787 DOI: 10.1111/mec.17359] [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: 09/24/2022] [Revised: 04/03/2024] [Accepted: 04/05/2024] [Indexed: 05/05/2024]
Abstract
Hybrid zones have been viewed as an opportunity to see speciation in action. When hybrid zones are replicated, it is assumed that if the same genetic incompatibilities are maintaining reproductive isolation across all instances of secondary contact, those incompatibilities should be identifiable by consistent patterns in the genome. In contrast, changes in allele frequencies due to genetic drift should be idiosyncratic for each hybrid zone. To test this assumption, we simulated 20 replicates of each of 12 hybrid zone scenarios with varied genetic incompatibilities, rates of migration, selection and different starting population size ratios of parental species. We found remarkable variability in the outcomes of hybridisation in replicate hybrid zones, particularly with Bateson-Dobzhansky-Muller incompatibilities and strong selection. We found substantial differences among replicates in the overall genomic composition of individuals, including admixture proportions, inter-specific ancestry complement and number of ancestry junctions. Additionally, we found substantial variation in genomic clines among replicates at focal loci, regardless of locus-specific selection. We conclude that processes other than selection are responsible for some consistent outcomes of hybridisation, whereas selection on incompatibilities can lead to genomically widespread and highly variable outcomes. We highlight the challenge of mapping between pattern and process in hybrid zones and call attention to how selection against incompatibilities will commonly lead to variable outcomes. We hope that this study informs future research on replicate hybrid zones and encourages further development of statistical techniques, theoretical models and exploration of additional axes of variation to understand reproductive isolation.
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Affiliation(s)
- S Eryn McFarlane
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Joshua P Jahner
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
| | | | - C Alex Buerkle
- Department of Botany, University of Wyoming, Laramie, Wyoming, USA
| | - Elizabeth G Mandeville
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
- Biology Department, Northern Michigan University, Marquette, Michigan, USA
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4
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Aguillon SM, Haase Cox SK, Langdon QK, Gunn TR, Baczenas JJ, Banerjee SM, Donny AE, Moran BM, Gutiérrez-Rodríguez C, Ríos-Cárdenas O, Morris MR, Powell DL, Schumer M. Pervasive gene flow despite strong and varied reproductive barriers in swordtails. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589374. [PMID: 38659793 PMCID: PMC11042374 DOI: 10.1101/2024.04.16.589374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
One of the mechanisms that can lead to the formation of new species occurs through the evolution of reproductive barriers. However, recent research has demonstrated that hybridization has been pervasive across the tree of life even in the presence of strong barriers. Swordtail fishes (genus Xiphophorus) are an emerging model system for studying the interface between these barriers and hybridization. We document overlapping mechanisms that act as barriers between closely related species, X. birchmanni and X. cortezi, by combining genomic sequencing from natural hybrid populations, artificial crosses, behavioral assays, sperm performance, and developmental studies. We show that strong assortative mating plays a key role in maintaining subpopulations with distinct ancestry in natural hybrid populations. Lab experiments demonstrate that artificial F1 crosses experience dysfunction: crosses with X. birchmanni females were largely inviable and crosses with X. cortezi females had a heavily skewed sex ratio. Using F2 hybrids we identify several genomic regions that strongly impact hybrid viability. Strikingly, two of these regions underlie genetic incompatibilities in hybrids between X. birchmanni and its sister species X. malinche. Our results demonstrate that ancient hybridization has played a role in the origin of this shared genetic incompatibility. Moreover, ancestry mismatch at these incompatible regions has remarkably similar consequences for phenotypes and hybrid survival in X. cortezi × X. birchmanni hybrids as in X. malinche × X. birchmanni hybrids. Our findings identify varied reproductive barriers that shape genetic exchange between naturally hybridizing species and highlight the complex evolutionary outcomes of hybridization.
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Affiliation(s)
- Stepfanie M. Aguillon
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - Quinn K. Langdon
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
- Gladstone Institute of Virology, Gladstone Institutes, San Francisco, CA, USA
| | - Theresa R. Gunn
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
| | | | - Shreya M. Banerjee
- Department of Biology, Stanford University, Stanford, CA, USA
- Center for Population Biology, University of California, Davis, Davis, CA, USA
| | | | - Benjamin M. Moran
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
| | | | - Oscar Ríos-Cárdenas
- Red de Biología Evolutiva, Instituto de Ecología A.C., Xalapa, Veracruz, México
| | - Molly R. Morris
- Department of Biological Sciences, Ohio University, Athens, Ohio, USA
| | - Daniel L. Powell
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
| | - Molly Schumer
- Department of Biology, Stanford University, Stanford, CA, USA
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Hidalgo, México
- Freeman Hrabowski Fellow, Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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5
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Deville D, Kawai K, Fujita H, Umino T. Genetic divergences and hybridization within the Sebastes inermis complex. PeerJ 2023; 11:e16391. [PMID: 38025733 PMCID: PMC10656903 DOI: 10.7717/peerj.16391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
The Sebastes inermis complex includes three sympatric species (Sebastes cheni, viz Sebastes inermis, and Sebastes ventricosus) with clear ecomorphological differences, albeit incomplete reproductive isolation. The presence of putative morphological hybrids (PMH) with plausibly higher fitness than the parent species indicates the need to confirm whether hybridization occurs within the complex. In this sense, we assessed the dynamics of genetic divergence and hybridization within the species complex using a panel of 10 microsatellite loci, and sequences of the mitochondrial control region (D-loop) and the intron-free rhodopsin (RH1) gene. The analyses revealed the presence of three distinct genetic clusters, large genetic distances using D-loop sequences, and distinctive mutations within the RH1 gene. These results are consistent with the descriptions of the three species. Two microsatellite loci had signatures of divergent selection, indicating that they are linked to genomic regions that are crucial for speciation. Furthermore, nonsynonymous mutations within the RH1 gene detected in S. cheni and "Kumano" (a PMH) suggest dissimilar adaptations related to visual perception in dim-light environments. The presence of individuals with admixed ancestry between two species confirmed hybridization. The presence of nonsynonymous mutations within the RH1 gene and the admixed ancestry of the "Kumano" morphotype highlight the potential role of hybridization in generating novelties within the species complex. We discuss possible outcomes of hybridization within the species complex, considering hybrid fitness and assortative mating. Overall, our findings indicate that the genetic divergence of each species is maintained in the presence of hybridization, as expected in a scenario of speciation-with-gene-flow.
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Affiliation(s)
- Diego Deville
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima, Japón
| | - Kentaro Kawai
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima, Japón
| | - Hiroki Fujita
- Seto Marine Biological Laboratory, Field Science Education and Research Center, Kyoto University, Shirahama, Wakayama, Japan
| | - Tetsuya Umino
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Hiroshima, Japón
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6
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Lu Y, Rice E, Du K, Kneitz S, Naville M, Dechaud C, Volff JN, Boswell M, Boswell W, Hillier L, Tomlinson C, Milin K, Walter RB, Schartl M, Warren WC. High resolution genomes of multiple Xiphophorus species provide new insights into microevolution, hybrid incompatibility, and epistasis. Genome Res 2023; 33:557-571. [PMID: 37147111 PMCID: PMC10234306 DOI: 10.1101/gr.277434.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 03/29/2023] [Indexed: 05/07/2023]
Abstract
Because of diverged adaptative phenotypes, fish species of the genus Xiphophorus have contributed to a wide range of research for a century. Existing Xiphophorus genome assemblies are not at the chromosomal level and are prone to sequence gaps, thus hindering advancement of the intra- and inter-species differences for evolutionary, comparative, and translational biomedical studies. Herein, we assembled high-quality chromosome-level genome assemblies for three distantly related Xiphophorus species, namely, X. maculatus, X. couchianus, and X. hellerii Our overall goal is to precisely assess microevolutionary processes in the clade to ascertain molecular events that led to the divergence of the Xiphophorus species and to progress understanding of genetic incompatibility to disease. In particular, we measured intra- and inter-species divergence and assessed gene expression dysregulation in reciprocal interspecies hybrids among the three species. We found expanded gene families and positively selected genes associated with live bearing, a special mode of reproduction. We also found positively selected gene families are significantly enriched in nonpolymorphic transposable elements, suggesting the dispersal of these nonpolymorphic transposable elements has accompanied the evolution of the genes, possibly by incorporating new regulatory elements in support of the Britten-Davidson hypothesis. We characterized inter-specific polymorphisms, structural variants, and polymorphic transposable element insertions and assessed their association to interspecies hybridization-induced gene expression dysregulation related to specific disease states in humans.
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Affiliation(s)
- Yuan Lu
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA;
| | - Edward Rice
- Department of Animal Sciences, Department of Surgery, Institute for Data Science and Informatics, University of Missouri, Bond Life Sciences Center, Columbia, Missouri 65201, USA
| | - Kang Du
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - Susanne Kneitz
- Biochemistry and Cell Biology, Biozentrum, University of Würzburg, 97074 Würzburg, Germany
| | - Magali Naville
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Corentin Dechaud
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Mikki Boswell
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - William Boswell
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - LaDeana Hillier
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Chad Tomlinson
- McDonnell Genome Institute, Washington University, St. Louis, Missouri 63108, USA
| | - Kremitzki Milin
- McDonnell Genome Institute, Washington University, St. Louis, Missouri 63108, USA
| | - Ronald B Walter
- Department of Life Sciences, Texas A&M University, Corpus Christi, Texas 78412, USA
| | - Manfred Schartl
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
- Developmental Biochemistry, Biozentrum, University of Würzburg, 97074 Würzburg, Germany
| | - Wesley C Warren
- Department of Animal Sciences, Department of Surgery, Institute for Data Science and Informatics, University of Missouri, Bond Life Sciences Center, Columbia, Missouri 65201, USA
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7
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Walsh J, Billerman SM, Butcher BG, Rohwer VG, Toews DPL, Vila-Coury V, Lovette IJ. A complex genomic architecture underlies reproductive isolation in a North American oriole hybrid zone. Commun Biol 2023; 6:154. [PMID: 36747071 PMCID: PMC9902562 DOI: 10.1038/s42003-023-04532-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 01/26/2023] [Indexed: 02/08/2023] Open
Abstract
Natural hybrid zones provide powerful opportunities for identifying the mechanisms that facilitate and inhibit speciation. Documenting the extent of genomic admixture allows us to discern the architecture of reproductive isolation through the identification of isolating barriers. This approach is particularly powerful for characterizing the accumulation of isolating barriers in systems exhibiting varying levels of genomic divergence. Here, we use a hybrid zone between two species-the Baltimore (Icterus galbula) and Bullock's (I. bullockii) orioles-to investigate this architecture of reproductive isolation. We combine whole genome re-sequencing with data from an additional 313 individuals amplityped at ancestry-informative markers to characterize fine-scale patterns of admixture, and to quantify links between genes and the plumage traits. On a genome-wide scale, we document several putative barriers to reproduction, including elevated peaks of divergence above a generally high genomic baseline, a large putative inversion on the Z chromosome, and complex interactions between melanogenesis-pathway candidate genes. Concordant and coincident clines for these different genomic regions further suggest the coupling of pre- and post-mating barriers. Our findings of complex and coupled interactions between pre- and post-mating barriers suggest a relatively rapid accumulation of barriers between these species, and they demonstrate the complexities of the speciation process.
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Affiliation(s)
- Jennifer Walsh
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA.
| | - Shawn M Billerman
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
| | - Bronwyn G Butcher
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
| | - Vanya G Rohwer
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
| | - David P L Toews
- Department of Biology, Penn State University, University Park, Pennsylvania, USA
| | - Vicens Vila-Coury
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
| | - Irby J Lovette
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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8
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Qvarnström A, Veen T, Husby A, Ålund M, Weissing FJ. Assortative Mating in an Ecological Context: Effects of Mate Choice Errors and Relative Species Abundance on the Frequency and Asymmetry of Hybridization. Am Nat 2023; 201:125-137. [PMID: 36524936 DOI: 10.1086/722156] [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: 11/03/2022]
Abstract
AbstractThe frequency and asymmetry of mixed-species mating set the initial stage for the ecological and evolutionary implications of hybridization. How such patterns of mixed-species mating, in turn, are influenced by the combination of mate choice errors and relative species abundance remains largely unknown. We develop a mathematical model that generates predictions for how relative species abundances and mate choice errors affect hybridization patterns. When mate choice errors are small (<5%), the highest frequency of hybridization occurs when one of the hybridizing species is at low abundance, but when mate choice errors are high (>5%), the highest hybridization frequency occurs when species occur in equal proportions. Furthermore, females of the less abundant species are overrepresented in mixed-species matings. We compare our theoretical predictions with empirical data on naturally hybridizing Ficedula flycatchers and find that hybridization is highest when the two species occur in equal abundance, implying rather high mate choice errors. We discuss ecological and evolutionary implications of our findings and encourage future work on hybrid zone dynamics that take demographic aspects, such as relative species abundance, into account.
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9
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Christie K, Fraser LS, Lowry DB. The strength of reproductive isolating barriers in seed plants: Insights from studies quantifying premating and postmating reproductive barriers over the past 15 years. Evolution 2022; 76:2228-2243. [PMID: 35838076 PMCID: PMC9796645 DOI: 10.1111/evo.14565] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 06/23/2022] [Accepted: 06/30/2022] [Indexed: 01/22/2023]
Abstract
Speciation is driven by the evolution of reproductive isolating barriers that reduce, and ultimately prevent, substantial gene flow between lineages. Despite its central role in evolutionary biology, the process can be difficult to study because it proceeds differently among groups and may occur over long timescales. Due to this complexity, we typically rely on generalizations of empirical data to describe and understand the process. Previous reviews of reproductive isolation (RI) in flowering plants have suggested that prezygotic or extrinsic barriers generally have a stronger effect on reducing gene flow compared to postzygotic or intrinsic barriers. Past conclusions have rested on relatively few empirical estimates of RI; however, RI data have become increasingly abundant over the past 15 years. We analyzed data from recent studies quantifying multiple pre- and postmating barriers in plants and compared the strengths of isolating barriers across 89 taxa pairs using standardized RI metrics. Individual prezygotic barriers were on average stronger than individual postzygotic barriers, and the total strength of prezygotic RI was approximately twice that of postzygotic RI. These findings corroborate that ecological divergence and extrinsic factors, as opposed to solely the accumulation of genetic incompatibilities, are important to speciation and the maintenance of species boundaries in plants. Despite an emphasis in the literature on asymmetric postmating and postzygotic RI, we found that prezygotic barriers acted equally asymmetrically. Overall, substantial variability in the strengths of 12 isolating barriers highlights the great diversity of mechanisms that contribute to plant diversification.
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Affiliation(s)
- Kyle Christie
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824,Department of Biological SciencesNorthern Arizona UniversityFlagstaffArizona86011
| | - Linnea S. Fraser
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824
| | - David B. Lowry
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan48824
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10
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Yang R, Deng YW, Liu Y, Zhao J, Bao L, Ge JP, Wang HF. Genetic structure and trait variation within a maple hybrid zone underscore North China as an overlooked diversity hotspot. Sci Rep 2022; 12:13949. [PMID: 35977961 PMCID: PMC9385851 DOI: 10.1038/s41598-022-17538-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/27/2022] [Indexed: 11/30/2022] Open
Abstract
Tertiary relict flora in East Asia can be divided into northern and southern regions. North China is a diversity hotspot because it can be the secondary contact zone of ancient lineages from the two regions. To test the extent of ancient lineages hybridization and distinguish between the putative species pair Acer pictum subsp. mono and Acer truncatum, we conducted genetic and ecological studies within a maple hybrid zone in North China. Our results suggest that the two lineages of Acer coexist in the hybrid zone and that adult and offspring populations show typical bimodal genetic patterns. Hybrid individuals are established at intermediate altitudes between the two parental lineages. Flowering phenology is divergent between lineages, whereas the complex sexual system of Acer may ensure pollination among lineages. Leaf and fruit morphologies are different between the northern and southern origin lineages, corresponding to A. pictum subsp. mono and A. truncatum, respectively. Reduced gene flow between lineages suggests that they should be considered as two species. However, large morphological variations within each species and the existence of hybrids offer low reliability of species identification based solely on morphological traits. Our study underscores North China as an overlooked diversity hotspot that requires further study in the future.
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Affiliation(s)
- Rui Yang
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China.,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China.,College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Ya-Wen Deng
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China.,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China.,College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Yan Liu
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China.,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China.,College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Jing Zhao
- Daheishan Administrative District, Beipiao City, 122000, Liaoning Province, China
| | - Lei Bao
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China.,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China.,College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Jian-Ping Ge
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China.,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China.,College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Hong-Fang Wang
- National Forestry and Grassland Administration Key Laboratory for Conservation Ecology in the Northeast Tiger and Leopard National Park, Beijing, 100875, China. .,Northeast Tiger and Leopard Biodiversity National Observation and Research Station, Beijing, 100875, China. .,College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
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11
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Muralidhar P, Coop G, Veller C. Assortative mating enhances postzygotic barriers to gene flow via ancestry bundling. Proc Natl Acad Sci U S A 2022; 119:e2122179119. [PMID: 35858444 PMCID: PMC9335313 DOI: 10.1073/pnas.2122179119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 06/06/2022] [Indexed: 01/21/2023] Open
Abstract
Hybridization and subsequent genetic introgression are now known to be common features of the histories of many species, including our own. Following hybridization, selection often purges introgressed DNA genome-wide. While assortative mating can limit hybridization in the first place, it is also known to play an important role in postzygotic selection against hybrids and, thus, the purging of introgressed DNA. However, this role is usually thought of as a direct one: a tendency for mates to be conspecific reduces the sexual fitness of hybrids, reducing the transmission of introgressed ancestry. Here, we explore a second, indirect role of assortative mating as a postzygotic barrier to gene flow. Under assortative mating, parents covary in their ancestry, causing ancestry to be "bundled" in their offspring and later generations. This bundling effect increases ancestry variance in the population, enhancing the efficiency with which postzygotic selection purges introgressed DNA. Using whole-genome simulations, we show that the bundling effect can comprise a substantial portion of mate choice's overall effect as a postzygotic barrier to gene flow. We then derive a simple method for estimating the impact of the bundling effect from standard metrics of assortative mating. Applying this method to data from a diverse set of hybrid zones, we find that the bundling effect increases the purging of introgressed DNA by between 1.2-fold (in a baboon system with weak assortative mating) and 14-fold (in a swordtail system with strong assortative mating). Thus, assortative mating's bundling effect contributes substantially to the genetic isolation of species.
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Affiliation(s)
- Pavitra Muralidhar
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
| | - Graham Coop
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
| | - Carl Veller
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
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12
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Payne C, Bovio R, Powell DL, Gunn TR, Banerjee SM, Grant V, Rosenthal GG, Schumer M. Genomic insights into variation in thermotolerance between hybridizing swordtail fishes. Mol Ecol 2022. [PMID: 35510780 DOI: 10.1111/mec.16489] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 02/22/2022] [Accepted: 04/19/2022] [Indexed: 11/30/2022]
Abstract
Understanding how organisms adapt to changing environments is a core focus of research in evolutionary biology. One common mechanism is adaptive introgression, which has received increasing attention as a potential route to rapid adaptation in populations struggling in the face of ecological change, particularly global climate change. However, hybridization can also result in deleterious genetic interactions that may limit the benefits of adaptive introgression. Here, we used a combination of genome-wide quantitative trait locus mapping and differential gene expression analyses between the swordtail fish species Xiphophorus malinche and X. birchmanni to study the consequences of hybridization on thermotolerance. While these two species are adapted to different thermal environments, we document a complicated architecture of thermotolerance in hybrids. We identify a region of the genome that contributes to reduced thermotolerance in individuals heterozygous for X. malinche and X. birchmanni ancestry, as well as widespread misexpression in hybrids of genes that respond to thermal stress in the parental species, particularly in the circadian clock pathway. We also show that a previously mapped hybrid incompatibility between X. malinche and X. birchmanni contributes to reduced thermotolerance in hybrids. Together, our results highlight the challenges of understanding the impact of hybridization on complex ecological traits and its potential impact on adaptive introgression.
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Affiliation(s)
- Cheyenne Payne
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
| | - Richard Bovio
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
- Department of Biology, Texas A&M University, College Station, Texas, USA
| | - Daniel L Powell
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
| | - Theresa R Gunn
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
| | - Shreya M Banerjee
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
| | - Victoria Grant
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
| | - Gil G Rosenthal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
- Department of Biology, Texas A&M University, College Station, Texas, USA
- Department of Biology, University of Padua, Italy
| | - Molly Schumer
- Department of Biology, Stanford University, Stanford, California, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, México
- Department of Biology, University of Padua, Italy
- Hanna H. Gray Fellow, Howard Hughes Medical Institute, Stanford, California, USA
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13
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Imbalanced segregation of recombinant haplotypes in hybrid populations reveals inter- and intrachromosomal Dobzhansky-Muller incompatibilities. PLoS Genet 2022; 18:e1010120. [PMID: 35344560 PMCID: PMC8989332 DOI: 10.1371/journal.pgen.1010120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 04/07/2022] [Accepted: 02/25/2022] [Indexed: 11/19/2022] Open
Abstract
Dobzhansky-Muller incompatibilities (DMIs) are a major component of reproductive isolation between species. DMIs imply negative epistasis and are exposed when two diverged populations hybridize. Mapping the locations of DMIs has largely relied on classical genetic mapping. Approaches to date are hampered by low power and the challenge of identifying DMI loci on the same chromosome, because strong initial linkage of parental haplotypes weakens statistical tests. Here, we propose new statistics to infer negative epistasis from haplotype frequencies in hybrid populations. When two divergent populations hybridize, the variance in heterozygosity at two loci decreases faster with time at DMI loci than at random pairs of loci. When two populations hybridize at near-even admixture proportions, the deviation of the observed variance from its expectation becomes negative for the DMI pair. This negative deviation enables us to detect intermediate to strong negative epistasis both within and between chromosomes. In practice, the detection window in hybrid populations depends on the demographic scenario, the recombination rate, and the strength of epistasis. When the initial proportion of the two parental populations is uneven, only strong DMIs can be detected with our method unless migration prevents parental haplotypes from being lost. We use the new statistics to infer candidate DMIs from three hybrid populations of swordtail fish. We identify numerous new DMI candidates, some of which are inferred to interact with several loci within and between chromosomes. Moreover, we discuss our results in the context of an expected enrichment in intrachromosomal over interchromosomal DMIs.
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14
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Langdon QK, Powell DL, Kim B, Banerjee SM, Payne C, Dodge TO, Moran B, Fascinetto-Zago P, Schumer M. Predictability and parallelism in the contemporary evolution of hybrid genomes. PLoS Genet 2022; 18:e1009914. [PMID: 35085234 PMCID: PMC8794199 DOI: 10.1371/journal.pgen.1009914] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/28/2021] [Indexed: 12/28/2022] Open
Abstract
Hybridization between species is widespread across the tree of life. As a result, many species, including our own, harbor regions of their genome derived from hybridization. Despite the recognition that this process is widespread, we understand little about how the genome stabilizes following hybridization, and whether the mechanisms driving this stabilization tend to be shared across species. Here, we dissect the drivers of variation in local ancestry across the genome in replicated hybridization events between two species pairs of swordtail fish: Xiphophorus birchmanni × X. cortezi and X. birchmanni × X. malinche. We find unexpectedly high levels of repeatability in local ancestry across the two types of hybrid populations. This repeatability is attributable in part to the fact that the recombination landscape and locations of functionally important elements play a major role in driving variation in local ancestry in both types of hybrid populations. Beyond these broad scale patterns, we identify dozens of regions of the genome where minor parent ancestry is unusually low or high across species pairs. Analysis of these regions points to shared sites under selection across species pairs, and in some cases, shared mechanisms of selection. We show that one such region is a previously unknown hybrid incompatibility that is shared across X. birchmanni × X. cortezi and X. birchmanni × X. malinche hybrid populations.
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Affiliation(s)
- Quinn K. Langdon
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Daniel L. Powell
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Bernard Kim
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Shreya M. Banerjee
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Cheyenne Payne
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Tristram O. Dodge
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Ben Moran
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
| | - Paola Fascinetto-Zago
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Molly Schumer
- Department of Biology, Stanford University, Stanford, California, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C., Calnali, Mexico
- Hanna H. Gray Fellow, Howard Hughes Medical Institutes, Chevy Chase, Maryland, United States of America
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15
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Metzler D, Knief U, Peñalba JV, Wolf JBW. Assortative mating and epistatic mating-trait architecture induce complex movement of the crow hybrid zone. Evolution 2021; 75:3154-3174. [PMID: 34694633 DOI: 10.1111/evo.14386] [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: 06/04/2021] [Accepted: 10/06/2021] [Indexed: 12/20/2022]
Abstract
Hybrid zones provide a window into the evolutionary processes governing species divergence. Yet, the contribution of mate choice to the temporal and spatial stability of hybrid zones remains poorly explored. Here, we investigate the effects of assortative mating on hybrid-zone dynamics by means of a mathematical model parameterized with phenotype and genotype data from the hybrid zone between all-black carrion and gray-coated hooded crows. In the best-fit model, narrow clines of the two mating-trait loci were maintained by a moderate degree of assortative mating inducing pre- and postzygotic isolation via positive frequency-dependent selection. Epistasis between the two loci induced hybrid-zone movement in favor of alleles conveying dark plumage followed by a shift in the opposite direction favoring gray-coated phenotypes ∼ 1 200 generations after secondary contact. Unlinked neutral loci diffused near-unimpeded across the zone. These results were generally robust to the choice of matching rule (self-referencing or parental imprinting) and effects of genetic drift. Overall, this study illustrates under which conditions assortative mating can maintain steep clines in mating-trait loci without generalizing to genome-wide reproductive isolation. It further emphasizes the importance of the genetic mating-trait architecture for spatio-temporal hybrid-zone dynamics.
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Affiliation(s)
- Dirk Metzler
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Ulrich Knief
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Joshua V Peñalba
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Jochen B W Wolf
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
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16
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Powell DL, Moran B, Kim B, Banerjee SM, Aguillon SM, Fascinetto-Zago P, Langdon Q, Schumer M. Two new hybrid populations expand the swordtail hybridization model system. Evolution 2021; 75:2524-2539. [PMID: 34460102 PMCID: PMC8659863 DOI: 10.1111/evo.14337] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/11/2021] [Accepted: 06/22/2021] [Indexed: 12/25/2022]
Abstract
Natural hybridization events provide unique windows into the barriers that keep species apart as well as the consequences of their breakdown. Here, we characterize hybrid populations formed between the northern swordtail fish Xiphophorus cortezi and Xiphophorus birchmanni from collection sites on two rivers. We use simulations and new genetic reference panels to develop sensitive and accurate local ancestry calling in this novel system. Strikingly, we find that hybrid populations on both rivers consist of two genetically distinct subpopulations: a cluster of pure X. birchmanni individuals and one of phenotypically intermediate hybrids that derive ∼85-90% of their genome from X. cortezi. Simulations suggest that initial hybridization occurred ∼150 generations ago at both sites, with little evidence for contemporary gene flow between subpopulations. This population structure is consistent with strong assortative mating between individuals of similar ancestry. The patterns of population structure uncovered here mirror those seen in hybridization between X. birchmanni and its sister species, Xiphophorus malinche, indicating an important role for assortative mating in the evolution of hybrid populations. Future comparisons will provide a window into the shared mechanisms driving the outcomes of hybridization not only among independent hybridization events between the same species but also across distinct species pairs.
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Affiliation(s)
- Daniel L. Powell
- Department of Biology, Stanford University,Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C.,Correspondence to: and
| | - Ben Moran
- Department of Biology, Stanford University,Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | | | - Shreya M. Banerjee
- Department of Biology, Stanford University,Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Stepfanie M. Aguillon
- Department of Biology, Stanford University,Department of Ecology and Evolutionary Biology, Cornell University
| | - Paola Fascinetto-Zago
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C.,Department of Biology, Texas A&M University
| | - Quinn Langdon
- Department of Biology, Stanford University,Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Molly Schumer
- Department of Biology, Stanford University,Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C.,Hanna H. Gray Fellow, Howard Hughes Medical Institutes,Correspondence to: and
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17
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Jofre GI, Rosenthal GG. A narrow window for geographic cline analysis using genomic data: Effects of age, drift, and migration on error rates. Mol Ecol Resour 2021; 21:2278-2287. [PMID: 33979028 DOI: 10.1111/1755-0998.13428] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 05/04/2021] [Accepted: 05/07/2021] [Indexed: 01/11/2023]
Abstract
The use of genomic and phenotypic data to scan for outliers is a mainstay for studies of hybridization and speciation. Geographic cline analysis of natural hybrid zones is widely used to identify putative signatures of selection by detecting deviations from baseline patterns of introgression. As with other outlier-based approaches, demographic histories can make neutral regions appear to be under selection and vice versa. In this study, we use a forward-time individual-based simulation approach to evaluate the robustness of geographic cline analysis under different evolutionary scenarios. We modelled multiple stepping-stone hybrid zones with distinct age, deme sizes, and migration rates, and evolving under different types of selection. We found that drift distorts cline shapes and increases false positive rates for signatures of selection. This effect increases with hybrid zone age, particularly if migration between demes is low. Drift can also distort the signature of deleterious effects of hybridization, with genetic incompatibilities and particularly underdominance prone to spurious typing as adaptive introgression. Our results suggest that geographic clines are most useful for outlier analysis in young hybrid zones with large populations of hybrid individuals. Current approaches may overestimate adaptive introgression and underestimate selection against maladaptive genotypes.
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Affiliation(s)
- Gaston I Jofre
- Department of Biology, Texas A&M University, TAMU, College Station, TX, USA.,Centro de Investigaciones Cientıficas de las Huastecas "Aguazarca", Calnali Hidalgo, Mexico.,Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Gil G Rosenthal
- Department of Biology, Texas A&M University, TAMU, College Station, TX, USA.,Centro de Investigaciones Cientıficas de las Huastecas "Aguazarca", Calnali Hidalgo, Mexico
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18
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Franklin-Alming FV, Kaspersen H, Hetland MAK, Bakksjø RJ, Nesse LL, Leangapichart T, Löhr IH, Telke AA, Sunde M. Exploring Klebsiella pneumoniae in Healthy Poultry Reveals High Genetic Diversity, Good Biofilm-Forming Abilities and Higher Prevalence in Turkeys Than Broilers. Front Microbiol 2021; 12:725414. [PMID: 34557173 PMCID: PMC8453068 DOI: 10.3389/fmicb.2021.725414] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/18/2021] [Indexed: 11/13/2022] Open
Abstract
Klebsiella pneumoniae is a well-studied human pathogen for which antimicrobial resistant and hypervirulent clones have emerged globally. K. pneumoniae is also present in a variety of environmental niches, but currently there is a lack of knowledge on the occurrence and characteristics of K. pneumoniae from non-human sources. Certain environmental niches, e.g., animals, may be associated with high K. pneumoniae abundance, and these can constitute a reservoir for further transmission of strains and genetic elements. The aim of this study was to explore and characterize K. pneumoniae from healthy broilers and turkeys. A total of 511 cecal samples (broiler n = 356, turkey n = 155), included in the Norwegian monitoring program for antimicrobial resistance (AMR) in the veterinary sector (NORM-VET) in 2018, were screened for K. pneumoniae by culturing on SCAI agar. K. pneumoniae was detected in 207 (40.5%) samples. Among the broiler samples, 25.8% were positive for K. pneumoniae, in contrast to turkey with 74.2% positive samples (p < 0.01). Antibiotic susceptibility testing was performed, in addition to investigating biofilm production. Whole genome sequencing was performed on 203 K. pneumoniae isolates, and analysis was performed utilizing comparative genomics tools. The genomes grouped into 66 sequence types (STs), with ST35, ST4710 and ST37 being the most prevalent at 13.8%, 7.4%, and 5.4%, respectively. The overall AMR occurrence was low, with only 11.3% of the isolates showing both pheno- and genotypic resistance. Genes encoding aerobactin, salmochelin or yersiniabactin were detected in 47 (23.2%) genomes. Fifteen hypervirulent genomes belonging to ST4710 and isolated from turkey were identified. These all encoded the siderophore virulence loci iuc5 and iro5 on an IncF plasmid. Isolates from both poultry species displayed good biofilm-forming abilities with an average of OD595 0.69 and 0.64. To conclude, the occurrence of K. pneumoniae in turkey was significantly higher than in broiler, indicating that turkey might be an important zoonotic reservoir for K. pneumoniae compared to broilers. Furthermore, our results show a highly diverse K. pneumoniae population in poultry, low levels of antimicrobial resistance, good biofilm-forming abilities and a novel hypervirulent ST4710 clone circulating in the turkey population.
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Affiliation(s)
- Fiona V Franklin-Alming
- Section for Microbiology, Department of Analysis and Diagnostics, Norwegian Veterinary Institute, Oslo, Norway
| | - Håkon Kaspersen
- Research Section Food Safety and Animal Health, Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
| | - Marit A K Hetland
- Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway.,Department of Biological Sciences, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen, Norway
| | - Ragna-Johanne Bakksjø
- Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway
| | - Live L Nesse
- Research Section Food Safety and Animal Health, Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
| | - Thongpan Leangapichart
- Research Section Food Safety and Animal Health, Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
| | - Iren H Löhr
- Department of Medical Microbiology, Stavanger University Hospital, Stavanger, Norway
| | - Amar A Telke
- Research Section Food Safety and Animal Health, Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
| | - Marianne Sunde
- Research Section Food Safety and Animal Health, Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway
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19
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Undin M, Lockhart PJ, Hills SFK, Armstrong DP, Castro I. Mixed Mating in a Multi-Origin Population Suggests High Potential for Genetic Rescue in North Island Brown Kiwi, Apteryx mantelli. FRONTIERS IN CONSERVATION SCIENCE 2021. [DOI: 10.3389/fcosc.2021.702128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Reinforcement translocations are increasingly utilised in conservation with the goal of achieving genetic rescue. However, concerns regarding undesirable results, such as genetic homogenisation or replacement, are widespread. One factor influencing translocation outcomes is the rate at which the resident and the introduced individuals interbreed. Consequently, post-release mate choice is a key behaviour to consider in conservation planning. Here we studied mating, and its consequences for genomic admixture, in the North Island brown kiwi Apteryx mantelli population on Ponui Island which was founded by two translocation events over 50 years ago. The two source populations used are now recognised as belonging to two separate management units between which birds differ in size and are genetically differentiated. We examined the correlation between male and female morphometrics for 17 known pairs and quantified the relatedness of 20 pairs from this admixed population. In addition, we compared the genetic similarity and makeup of 106 Ponui Island birds, including 23 known pairs, to birds representing the source populations for the original translocations. We found no evidence for size-assortative mating. On the contrary, genomic SNP data suggested that kiwi of one feather did not flock together, meaning that mate choice resulted in pairing between individuals that were less related than expected by random chance. Furthermore, the birds in the current Ponui Island population were found to fall along a gradient of genomic composition consistent with non-clustered representation of the two parental genomes. These findings indicate potential for successful genetic rescue in future Apteryx reinforcement translocations, a potential that is currently under utilised due to restrictive translocation policies. In light of our findings, we suggest that reconsideration of these policies could render great benefits for the future diversity of this iconic genus in New Zealand.
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20
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Moran BM, Payne C, Langdon Q, Powell DL, Brandvain Y, Schumer M. The genomic consequences of hybridization. eLife 2021; 10:e69016. [PMID: 34346866 PMCID: PMC8337078 DOI: 10.7554/elife.69016] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/09/2021] [Indexed: 12/29/2022] Open
Abstract
In the past decade, advances in genome sequencing have allowed researchers to uncover the history of hybridization in diverse groups of species, including our own. Although the field has made impressive progress in documenting the extent of natural hybridization, both historical and recent, there are still many unanswered questions about its genetic and evolutionary consequences. Recent work has suggested that the outcomes of hybridization in the genome may be in part predictable, but many open questions about the nature of selection on hybrids and the biological variables that shape such selection have hampered progress in this area. We synthesize what is known about the mechanisms that drive changes in ancestry in the genome after hybridization, highlight major unresolved questions, and discuss their implications for the predictability of genome evolution after hybridization.
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Affiliation(s)
- Benjamin M Moran
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Cheyenne Payne
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Quinn Langdon
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Daniel L Powell
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Yaniv Brandvain
- Department of Ecology, Evolution & Behavior and Plant and Microbial Biology, University of MinnesotaMinneapolisUnited States
| | - Molly Schumer
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
- Hanna H. Gray Fellow, Howard Hughes Medical InstituteStanfordUnited States
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21
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Jahner JP, Parchman TL, Matocq MD. Multigenerational backcrossing and introgression between two woodrat species at an abrupt ecological transition. Mol Ecol 2021; 30:4245-4258. [PMID: 34219316 DOI: 10.1111/mec.16056] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/28/2021] [Indexed: 12/27/2022]
Abstract
When organisms experience secondary contact after allopatric divergence, genomic regions can introgress differentially depending on their relationships with adaptation, reproductive isolation, recombination, and drift. Analyses of genome-wide patterns of divergence and introgression could provide insight into the outcomes of hybridization and the potential relationship between allopatric divergence and reproductive isolation. Here, we generate population genetic data (26,262 SNPs; 353 individuals) using a reduced-representation sequencing approach to quantify patterns of ancestry, differentiation, and introgression between a pair of ecologically distinct mammals-the desert woodrat (N. lepida) and Bryant's woodrat (N. bryanti)-that hybridize at a sharp ecotone in southern California. Individual ancestry estimates confirmed that hybrids were rare in this bimodal hybrid zone, and entirely consisted of a few F1 individuals and a broad range of multigenerational backcrosses. Genomic cline analyses indicated more than half of loci had elevated introgression from one genomic background into the other. However, introgression was not associated with relative or absolute measures of divergence, and loci with extreme values for both were not typically found near detoxification enzymes previously implicated in dietary specialization for woodrats. The decoupling of differentiation and introgression suggests that processes other than adaptation, such as drift, may underlie the extreme clines at this contact zone.
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Affiliation(s)
- Joshua P Jahner
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Department of Botany, University of Wyoming, Laramie, Wyoming, USA
| | - Thomas L Parchman
- Department of Biology, University of Nevada, Reno, Nevada, USA.,Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA
| | - Marjorie D Matocq
- Program in Ecology, Evolution, and Conservation Biology, University of Nevada, Reno, Nevada, USA.,Department of Natural Resources and Environmental Science, University of Nevada, Reno, Nevada, USA
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22
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Mikkelsen EK, Irwin D. Ongoing production of low-fitness hybrids limits range overlap between divergent cryptic species. Mol Ecol 2021; 30:4090-4102. [PMID: 34101940 DOI: 10.1111/mec.16015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 05/13/2021] [Accepted: 05/26/2021] [Indexed: 01/23/2023]
Abstract
Contact zones between recently diverged taxa provide opportunities to examine the causes of reproductive isolation and the processes that determine whether two species can coexist over a broad region. The Pacific wren (Troglodytes pacificus) and winter wren (Troglodytes hiemalis) are two morphologically similar songbirds that started diverging about 4 million years ago, older than most sister species pairs of temperate songbirds. The ranges of these species come into narrow contact in western Canada, where the two species remain distinct. To assess evidence for differentiation, hybridization and introgression in this system, we examined variation in over 250,000 single nucleotide polymorphism markers distributed across the genome. The two species formed highly divergent genetic clusters, consistent with long-term differentiation. In a set of 75 individuals, two first-generation hybrids (i.e., F1 's) were detected, indicating only moderate levels of assortative mating between these taxa. We found no recent backcrosses or other evidence of recent breeding success of F1 's, indicating very low or zero fitness of F1 hybrids. Examination of genomic variation shows evidence for only a single backcrossing event many generations ago. The moderate rate of hybridization combined with very low F1 hybrid fitness is expected to result in a population sink in the contact zone, largely explaining the narrow overlap of the two species. If such dynamics are common in nature, they could explain the narrow range overlap often observed between pairs of closely related species.
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Affiliation(s)
- Else K Mikkelsen
- Department of Zoology, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Darren Irwin
- Department of Zoology, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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23
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Brachmann MK, Parsons K, Skúlason S, Ferguson MM. The interaction of resource use and gene flow on the phenotypic divergence of benthic and pelagic morphs of Icelandic Arctic charr ( Salvelinus alpinus). Ecol Evol 2021; 11:7315-7334. [PMID: 34188815 PMCID: PMC8216915 DOI: 10.1002/ece3.7563] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 02/09/2021] [Accepted: 03/02/2021] [Indexed: 12/11/2022] Open
Abstract
Conceptual models of adaptive divergence and ecological speciation in sympatry predict differential resource use, phenotype-environment correlations, and reduced gene flow among diverging phenotypes. While these predictions have been assessed in past studies, connections among them have rarely been assessed collectively. We examined relationships among phenotypic, ecological, and genetic variation in Arctic charr (Salvelinus alpinus) from six Icelandic localities that have undergone varying degrees of divergence into sympatric benthic and pelagic morphs. We characterized morphological variation with geometric morphometrics, tested for differential resource use between morphs using stable isotopes, and inferred the amount of gene flow from single nucleotide polymorphisms. Analysis of stable isotopic signatures indicated that sympatric morphs showed similar difference in resource use across populations, likely arising from the common utilization of niche space within each population. Carbon isotopic signature was also a significant predictor of individual variation in body shape and size, suggesting that variation in benthic and pelagic resource use is associated with phenotypic variation. The estimated percentage of hybrids between sympatric morphs varied across populations (from 0% to 15.6%) but the majority of fish had genotypes (ancestry coefficients) characteristic of pure morphs. Despite evidence of reduced gene flow between sympatric morphs, we did not detect the expected negative relationship between divergence in resource use and gene flow. Three lakes showed the expected pattern, but morphs in the fourth showed no detectable hybridization and had relatively low differences in resource use between them. This coupled with the finding that resource use and genetic differentiation had differential effects on body shape variation across populations suggests that reproductive isolation maintains phenotypic divergence between benthic and pelagic morphs when the effects of resource use are relatively low. Our ability to assess relationships between phenotype, ecology, and genetics deepens our understanding of the processes underlying adaptive divergence in sympatry.
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Affiliation(s)
| | - Kevin Parsons
- Institute of Biodiversity, Animal Health and Comparative MedicineSchool of Life ScienceUniversity of GlasgowGlasgowUK
| | - Skúli Skúlason
- Department of Aquaculture and Fish BiologyHólar UniversitySaudárkrókurIceland
- Icelandic Museum of Natural HistoryReykjavíkIceland
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24
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Powell DL, Payne C, Banerjee SM, Keegan M, Bashkirova E, Cui R, Andolfatto P, Rosenthal GG, Schumer M. The Genetic Architecture of Variation in the Sexually Selected Sword Ornament and Its Evolution in Hybrid Populations. Curr Biol 2021; 31:923-935.e11. [PMID: 33513352 DOI: 10.1016/j.cub.2020.12.049] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/27/2020] [Accepted: 12/25/2020] [Indexed: 10/22/2022]
Abstract
Biologists since Darwin have been fascinated by the evolution of sexually selected ornaments, particularly those that reduce viability. Uncovering the genetic architecture of these traits is key to understanding how they evolve and are maintained. Here, we investigate the genetic architecture and evolutionary loss of a sexually selected ornament, the "sword" fin extension that characterizes many species of swordtail fish (Xiphophorus). Using sworded and swordless sister species of Xiphophorus, we generated a mapping population and show that the sword ornament is polygenic-with ancestry across the genome explaining substantial variation in the trait. After accounting for the impacts of genome-wide ancestry, we identify one major-effect quantitative trait locus (QTL) that explains ~5% of the overall variation in the trait. Using a series of approaches, we narrow this large QTL interval to several likely candidate genes, including genes involved in fin regeneration and growth. Furthermore, we find evidence of selection on ancestry at one of these candidates in four natural hybrid populations, consistent with selection against the sword in these populations.
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Affiliation(s)
- Daniel L Powell
- Department of Biology, Stanford University, 327 Campus Drive, Stanford, CA 94305, USA; Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México; Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX 77843, USA.
| | - Cheyenne Payne
- Department of Biology, Stanford University, 327 Campus Drive, Stanford, CA 94305, USA; Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México
| | - Shreya M Banerjee
- Department of Biology, Stanford University, 327 Campus Drive, Stanford, CA 94305, USA; Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México
| | - Mackenzie Keegan
- Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Elizaveta Bashkirova
- Department of Biochemistry and Molecular Biophysics, Columbia University, 701 West 168th Street, New York, NY 10032, USA; Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University Irving Medical Center, 622 West 168th Street, New York, NY 10032, USA
| | - Rongfeng Cui
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México; Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX 77843, USA; Max Planck Institute for the Biology of Aging, Postfach 41 06 23, 50931 Cologne, Germany; School of Ecology, Sun Yat-sen University, 135 Xingang West Road, Binjiang Road, Haizhu District, Guangdong Province, China
| | - Peter Andolfatto
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Avenue, New York, NY 10027, USA
| | - Gil G Rosenthal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México; Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX 77843, USA
| | - Molly Schumer
- Department of Biology, Stanford University, 327 Campus Drive, Stanford, CA 94305, USA; Centro de Investigaciones Científicas de las Huastecas "Aguazarca," A.C., 16 de Septiembre, 392 Barrio Aguazarca, Calnali, Hidalgo 43240, México; Howard Hughes Medical Institute, 327 Campus Drive, Stanford, CA 94305, USA.
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25
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Broder ED, Elias DO, Rodríguez RL, Rosenthal GG, Seymoure BM, Tinghitella RM. Evolutionary novelty in communication between the sexes. Biol Lett 2021; 17:20200733. [PMID: 33529546 PMCID: PMC8086948 DOI: 10.1098/rsbl.2020.0733] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/11/2021] [Indexed: 12/18/2022] Open
Abstract
The diversity of signalling traits within and across taxa is vast and striking, prompting us to consider how novelty evolves in the context of animal communication. Sexual selection contributes to diversification, and here we endeavour to understand the initial conditions that facilitate the maintenance or elimination of new sexual signals and receiver features. New sender and receiver variants can occur through mutation, plasticity, hybridization and cultural innovation, and the initial conditions of the sender, the receiver and the environment then dictate whether a novel cue becomes a signal. New features may arise in the sender, the receiver or both simultaneously. We contend that it may be easier than assumed to evolve new sexual signals because sexual signals may be arbitrary, sexual conflict is common and receivers are capable of perceiving much more of the world than just existing sexual signals. Additionally, changes in the signalling environment can approximate both signal and receiver changes through a change in transmission characteristics of a given environment or the use of new environments. The Anthropocene has led to wide-scale disruption of the environment and may thus generate opportunity to directly observe the evolution of new signals to address questions that are beyond the reach of phylogenetic approaches.
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Affiliation(s)
- E. Dale Broder
- Department of Biology, St Ambrose University, Davenport, IA 52803, USA
| | - Damian O. Elias
- Department of Environmental Science, Policy and Management, UC Berkeley, Berkeley, CA 94720, USA
| | - Rafael L. Rodríguez
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
| | - Gil G. Rosenthal
- Department of Biology, Texas A&M, College Station, TX 77843, USA
| | - Brett M. Seymoure
- Living Earth Collaborative, Washington University in St. Louis, St. Louis, MO 63130, USA
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26
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Sato K, Yamamoto D. Contact-Chemosensory Evolution Underlying Reproductive Isolation in Drosophila Species. Front Behav Neurosci 2020; 14:597428. [PMID: 33343311 PMCID: PMC7746553 DOI: 10.3389/fnbeh.2020.597428] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/11/2020] [Indexed: 11/13/2022] Open
Abstract
The main theme of the review is how changes in pheromone biochemistry and the sensory circuits underlying pheromone detection contribute to mate choice and reproductive isolation. The review focuses primarily on gustatory and non-volatile signals in Drosophila. Premating isolation is prevalent among closely related species. In Drosophila, preference for conspecifics against other species in mate choice underlies premating isolation, and such preference relies on contact chemosensory communications between a female and male along with other biological factors. For example, although D. simulans and D. melanogaster are sibling species that yield hybrids, their premating isolation is maintained primarily by the contrasting effects of 7,11-heptacosadiene (7,11-HD), a predominant female pheromone in D. melanogaster, on males of the two species: it attracts D. melanogaster males and repels D. simulans males. The contrasting preference for 7,11-HD in males of these two species is mainly ascribed to opposite effects of 7,11-HD on neural activities in the courtship decision-making neurons in the male brain: 7,11-HD provokes both excitatory and inhibitory inputs in these neurons and differences in the balance between the two counteracting inputs result in the contrasting preference for 7,11-HD, i.e., attraction in D. melanogaster and repulsion in D. simulans. Introduction of two double bonds is a key step in 7,11-HD biosynthesis and is mediated by the desaturase desatF, which is active in D. melanogaster females but transcriptionally inactivated in D. simulans females. Thus, 7,11-HD biosynthesis diversified in females and 7,11-HD perception diversified in males, yet it remains elusive how concordance of the changes in the two sexes was attained in evolution.
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Affiliation(s)
| | - Daisuke Yamamoto
- Neuro-Network Evolution Project, Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
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27
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Coughlan JM, Matute DR. The importance of intrinsic postzygotic barriers throughout the speciation process. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190533. [PMID: 32654642 DOI: 10.1098/rstb.2019.0533] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Intrinsic postzygotic barriers can play an important and multifaceted role in speciation, but their contribution is often thought to be reserved to the final stages of the speciation process. Here, we review how intrinsic postzygotic barriers can contribute to speciation, and how this role may change through time. We outline three major contributions of intrinsic postzygotic barriers to speciation. (i) reduction of gene flow: intrinsic postzygotic barriers can effectively reduce gene exchange between sympatric species pairs. We discuss the factors that influence how effective incompatibilities are in limiting gene flow. (ii) early onset of species boundaries via rapid evolution: intrinsic postzygotic barriers can evolve between recently diverged populations or incipient species, thereby influencing speciation relatively early in the process. We discuss why the early origination of incompatibilities is expected under some biological models, and detail how other (and often less obvious) incompatibilities may also serve as important barriers early on in speciation. (iii) reinforcement: intrinsic postzygotic barriers can promote the evolution of subsequent reproductive isolation through processes such as reinforcement, even between relatively recently diverged species pairs. We incorporate classic and recent empirical and theoretical work to explore these three facets of intrinsic postzygotic barriers, and provide our thoughts on recent challenges and areas in the field in which progress can be made. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- Jenn M Coughlan
- Department of Biology, University of North Carolina, 120 South Road, Coker Hall, Chapel Hill, NC 27599, USA
| | - Daniel R Matute
- Department of Biology, University of North Carolina, 120 South Road, Coker Hall, Chapel Hill, NC 27599, USA
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28
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Stewart KA, Taylor SA. Leveraging eDNA to expand the study of hybrid zones. Mol Ecol 2020; 29:2768-2776. [PMID: 32557920 PMCID: PMC7496085 DOI: 10.1111/mec.15514] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 04/18/2020] [Accepted: 06/05/2020] [Indexed: 02/06/2023]
Abstract
Hybrid zones are important windows into ecological and evolutionary processes. Our understanding of the significance and prevalence of hybridization in nature has expanded with the generation and analysis of genome‐spanning data sets. That said, most hybridization research still has restricted temporal and spatial resolution, which limits our ability to draw broad conclusions about evolutionary and conservation related outcomes. Here, we argue that rapidly advancing environmental DNA (eDNA) methodology could be adopted for studies of hybrid zones to increase temporal sampling (contemporary and historical), refine and geographically expand sampling density, and collect data for taxa that are difficult to directly sample. Genomic data in the environment offer the potential for near real‐time biological tracking of hybrid zones, and eDNA provides broad, but as yet untapped, potential to address eco‐evolutionary questions.
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Affiliation(s)
- Kathryn A Stewart
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Scott A Taylor
- Department Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, USA
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29
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Irwin DE. Assortative Mating in Hybrid Zones Is Remarkably Ineffective in Promoting Speciation. Am Nat 2020; 195:E150-E167. [DOI: 10.1086/708529] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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30
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Powell DL, García-Olazábal M, Keegan M, Reilly P, Du K, Díaz-Loyo AP, Banerjee S, Blakkan D, Reich D, Andolfatto P, Rosenthal GG, Schartl M, Schumer M. Natural hybridization reveals incompatible alleles that cause melanoma in swordtail fish. Science 2020; 368:731-736. [PMID: 32409469 PMCID: PMC8074799 DOI: 10.1126/science.aba5216] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/27/2020] [Indexed: 12/21/2022]
Abstract
The establishment of reproductive barriers between populations can fuel the evolution of new species. A genetic framework for this process posits that "incompatible" interactions between genes can evolve that result in reduced survival or reproduction in hybrids. However, progress has been slow in identifying individual genes that underlie hybrid incompatibilities. We used a combination of approaches to map the genes that drive the development of an incompatibility that causes melanoma in swordtail fish hybrids. One of the genes involved in this incompatibility also causes melanoma in hybrids between distantly related species. Moreover, this melanoma reduces survival in the wild, likely because of progressive degradation of the fin. This work identifies genes underlying a vertebrate hybrid incompatibility and provides a glimpse into the action of these genes in natural hybrid populations.
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Affiliation(s)
- Daniel L Powell
- Department of Biology, Stanford University and Howard Hughes Medical Institute, Stanford, CA, USA.
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Mateo García-Olazábal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | | | - Patrick Reilly
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Kang Du
- Developmental Biochemistry, Biocenter, University of Würzburg, Würzburg, Bavaria, Germany
| | - Alejandra P Díaz-Loyo
- Laboratorio de Ecología de la Conducta, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Shreya Banerjee
- Department of Biology, Stanford University and Howard Hughes Medical Institute, Stanford, CA, USA
| | - Danielle Blakkan
- Department of Biology, Stanford University and Howard Hughes Medical Institute, Stanford, CA, USA
| | - David Reich
- Department of Genetics, Harvard Medical School, Howard Hughes Medical Institute, and the Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Peter Andolfatto
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Gil G Rosenthal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Manfred Schartl
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca", A.C., Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
- Developmental Biochemistry, Biocenter, University of Würzburg, Würzburg, Bavaria, Germany
- Hagler Institute for Advanced Study, Texas A&M University, College Station, TX, USA
- Xiphophorus Genetic Stock Center, Texas State University San Marcos, San Marcos, TX, USA
| | - Molly Schumer
- Department of Biology, Stanford University and Howard Hughes Medical Institute, Stanford, CA, USA.
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31
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Goldberg A, Rastogi A, Rosenberg NA. Assortative mating by population of origin in a mechanistic model of admixture. Theor Popul Biol 2020; 134:129-146. [PMID: 32275920 DOI: 10.1016/j.tpb.2020.02.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/11/2020] [Accepted: 02/27/2020] [Indexed: 02/01/2023]
Abstract
Populations whose mating pairs have levels of similarity in phenotypes or genotypes that differ systematically from the level expected under random mating are described as experiencing assortative mating. Excess similarity in mating pairs is termed positive assortative mating, and excess dissimilarity is negative assortative mating. In humans, empirical studies suggest that mating pairs from various admixed populations - whose ancestry derives from two or more source populations - possess correlated ancestry components that indicate the occurrence of positive assortative mating on the basis of ancestry. Generalizing a two-sex mechanistic admixture model, we devise a model of one form of ancestry-assortative mating that occurs through preferential mating based on source population. Under the model, we study the moments of the admixture fraction distribution for different assumptions about mating preferences, including both positive and negative assortative mating by population. We demonstrate that whereas the mean admixture under assortative mating is equivalent to that of a corresponding randomly mating population, the variance of admixture depends on the level and direction of assortative mating. We consider two special cases of assortative mating by population: first, a single admixture event, and second, constant contributions to the admixed population over time. In contrast to standard settings in which positive assortment increases variation within a population, certain assortative mating scenarios allow the variance of admixture to decrease relative to a corresponding randomly mating population: with the three populations we consider, the variance-increasing effect of positive assortative mating within a population might be overwhelmed by a variance-decreasing effect emerging from mating preferences involving other pairs of populations. The effect of assortative mating is smaller on the X chromosome than on the autosomes because inheritance of the X in males depends only on the mother's ancestry, not on the mating pair. Because the variance of admixture is informative about the timing of admixture and possibly about sex-biased admixture contributions, the effects of assortative mating are important to consider in inferring features of population history from distributions of admixture values. Our model provides a framework to quantitatively study assortative mating under flexible scenarios of admixture over time.
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Affiliation(s)
- Amy Goldberg
- Department of Evolutionary Anthropology, Duke University, Durham, NC, USA; Department of Biology, Stanford University, Stanford, CA, USA.
| | - Ananya Rastogi
- Department of Systems Immunology & Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
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32
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Wagner DN, Curry RL, Chen N, Lovette IJ, Taylor SA. Genomic regions underlying metabolic and neuronal signaling pathways are temporally consistent in a moving avian hybrid zone. Evolution 2020; 74:1498-1513. [PMID: 32243568 DOI: 10.1111/evo.13970] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 12/15/2022]
Abstract
The study of hybrid zones can provide insight into the genetic basis of species differences that are relevant for the maintenance of reproductive isolation. Hybrid zones can also provide insight into climate change, species distributions, and evolution. The hybrid zone between black-capped chickadees (Poecile atricapillus) and Carolina chickadees (Poecile carolinensis) is shifting northward in response to increasing winter temperatures but is not increasing in width. This pattern indicates strong selection against chickadees with admixed genomes. Using high-resolution genomic data, we identified regions of the genomes that are outliers in both time points and do not introgress between the species; these regions may be involved in the maintenance of reproductive isolation. Genes involved in metabolic regulation processes were overrepresented in this dataset. Several gene ontology categories were also temporally consistent-including glutamate signaling, synaptic transmission, and catabolic processes-but the nucleotide variants leading to this pattern were not. Our results support recent findings that hybrids between black-capped and Carolina chickadees have higher basal metabolic rates than either parental species and suffer spatial memory and problem-solving deficits. Metabolic breakdown, as well as spatial memory and problem-solving, in hybrid chickadees may act as strong postzygotic isolation mechanisms in this moving hybrid zone.
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Affiliation(s)
- Dominique N Wagner
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
| | - Robert L Curry
- Department of Biology, Villanova University, Villanova, Pennsylvania, 19085
| | - Nancy Chen
- Department of Biology, University of Rochester, Rochester, New York, 14627
| | - Irby J Lovette
- Cornell Lab of Ornithology, Cornell University, Ithaca, New York, 14850
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, 80309
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33
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Sawangproh W, Hedenäs L, Lang AS, Hansson B, Cronberg N. Gene transfer across species boundaries in bryophytes: evidence from major life cycle stages in Homalothecium lutescens and H. sericeum. ANNALS OF BOTANY 2020; 125:565-579. [PMID: 31872857 PMCID: PMC7102947 DOI: 10.1093/aob/mcz209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/20/2019] [Indexed: 05/14/2023]
Abstract
BACKGROUND AND AIMS The mosses Homalothecium lutescens and H. sericeum are genetically, morphologically and ecologically differentiated; mixed populations sometimes occur. In sympatric populations, intermediate character states among gametophytes and sporophytes have been observed, suggesting hybridization and introgression in such populations. METHODS We determined genotypes using bi-allelic co-dominant single nucleotide polymorphism (SNP) markers, specific to either H. lutescens or H. sericeum, to estimate the degree of genetic mixing in 449 moss samples collected from seven sympatric and five allopatric populations on the island of Öland, south Sweden. The samples represented three generations: haploid maternal gametophytes; diploid sporophytes; and haploid sporelings. KEY RESULTS Admixture analyses of SNP genotypes identified a majority as pure H. lutescens or H. sericeum, but 76 samples were identified as mildly admixed (17 %) and 17 samples (3.8 %) as strongly admixed. Admixed samples were represented in all three generations in several populations. Hybridization and introgression were bidirectional. CONCLUSIONS Our results demonstrate that admixed genomes are transferred between the generations, so that the populations behave as true hybrid zones. Earlier studies of sympatric bryophyte populations with admixed individuals have not been able to show that admixed alleles are transferred beyond the first generation. The presence of true hybrid zones has strong evolutionary implications because genetic material transferred across species boundaries can be directly exposed to selection in the long-lived haploid generation of the bryophyte life cycle, and contribute to local adaptation, long-term survival and speciation.
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Affiliation(s)
- W Sawangproh
- Biodiversity, Department of Biology, Lund University, Lund, Sweden
- Division of Conservation Biology, School of Interdisciplinary Studies, Mahidol University (Kanchanaburi Campus), Kanchanaburi Province, Thailand
| | - L Hedenäs
- Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden
| | - A S Lang
- Biodiversity, Department of Biology, Lund University, Lund, Sweden
| | - B Hansson
- Department of Biology, Lund University, Lund, Sweden
| | - N Cronberg
- Biodiversity, Department of Biology, Lund University, Lund, Sweden
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34
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Delclos PJ, Forero SA, Rosenthal GG. Divergent neurogenomic responses shape social learning of both personality and mate preference. J Exp Biol 2020; 223:jeb220707. [PMID: 32054683 DOI: 10.1242/jeb.220707] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/05/2020] [Indexed: 12/21/2022]
Abstract
Behavior plays a fundamental role in shaping the origin and fate of species. Mating decisions can act to promote or restrict gene flow, as can personality traits that influence dispersal and niche use. Mate choice and personality are often both learned and therefore influenced by an individual's social environment throughout development. Likewise, the molecular pathways that shape these behaviors may also be co-expressed. In this study on swordtail fish (Xiphophorus birchmanni), we show that female mating preferences for species-typical pheromone cues are entirely dependent on social experience with adult males. Experience with adults also shapes development along the shy-bold personality axis, with shy behaviors arising from exposure to risk-averse heterospecifics as a potential stress-coping strategy. In maturing females, conspecific exposure results in a strong upregulation of olfaction and vision genes compared with heterospecific exposure, as well as immune response genes previously linked to anxiety, learning and memory. Conversely, heterospecific exposure involves an increased expression of genes important for neurogenesis, synaptic plasticity and social decision-making. We identify subsets of genes within the social decision-making network and with known stress-coping roles that may be directly coupled to the olfactory processes females rely on for social communication. Based on these results, we conclude that the social environment affects the neurogenomic trajectory through which socially sensitive behaviors are learned, resulting in adult phenotypes adapted for specific social groupings.
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Affiliation(s)
- Pablo J Delclos
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
- Centro de Investigaciones Científicas de las Huastecas 'Aguazarca', A. C., Calnali, Hidalgo 43233, Mexico
- Department of Biology & Biochemistry, University of Houston, Houston, TX 77004, USA
| | - Santiago A Forero
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
- Department of Psychology, Cornell University, Ithaca, NY 14850, USA
| | - Gil G Rosenthal
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
- Centro de Investigaciones Científicas de las Huastecas 'Aguazarca', A. C., Calnali, Hidalgo 43233, Mexico
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35
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Moser FN, Wilson AB. Reproductive isolation following hybrid speciation in Mediterranean pipefish (Syngnathus spp.). Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Knutson AE, Tracy JL, Ritzi C, Moran PJ, Royer T, Deloach CJ. Establishment, Hybridization, Dispersal, Impact, and Decline of Diorhabda spp. (Coleoptera: Chrysomelidae) Released for Biological Control of Tamarisk in Texas and New Mexico. ENVIRONMENTAL ENTOMOLOGY 2019; 48:1297-1316. [PMID: 31603984 DOI: 10.1093/ee/nvz107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Indexed: 06/10/2023]
Abstract
Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from 2003 to 2010 for biological control of tamarisk (Tamarix spp.): Mediterranean tamarisk beetles, D. elongata (Brullé) from Greece, also established in New Mexico; subtropical tamarisk beetles, D. sublineata (Lucas) from Tunisia; and larger tamarisk beetles, D. carinata (Faldermann) from Uzbekistan. More than one million tamarisk beetles were released at 99 sites. Species establishment success ranged from 52 to 83%. All three species now co-occur in New Mexico with the northern tamarisk beetles, D. carinulata (Desbrochers). A phenotypic hybrid scoring system was developed to assess Diorhabda phenotype distributions and character mixing in hybrid zones. Widespread field populations of bispecific hybrid phenotypes for D. carinata/D. elongata and D. sublineata/D. elongata rapidly appeared following contact of parental species. Initial distributions and dispersal of Diorhabda spp. and hybrids are mapped for Texas, New Mexico, Oklahoma, and Kansas, where they produced large-scale tamarisk defoliation and localized dieback for 3-4 yr. However, populations subsequently severely declined, now producing only isolated defoliation and allowing tamarisk to recover. Diorhabda sublineata and D. elongata temporarily produced nontarget spillover defoliation of ornamental athel, Tamarix aphylla (L.) Karst, along the Rio Grande. Hybrid phenotypes were generally bimodally distributed, indicating some degree of reproductive isolation. Additional diagnostic phenotypic characters in males allowed more precise hybrid scoring. Character mixing in some hybrid populations approached or reached that of a hybrid swarm. The significance of hybridization for tamarisk biocontrol is discussed.
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Affiliation(s)
- Allen E Knutson
- Texas A&M AgriLife Extension, Department of Entomology, Texas A&M AgriLife Research and Extension Center, Dallas, TX
| | - James L Tracy
- Knowledge Engineering Laboratory, Department of Entomology, Texas A&M University, TAMU, College Station, TX
| | - Chris Ritzi
- Biology, Geology, and Physical Sciences Department, Sul Ross State University, Alpine, TX
| | - Patrick J Moran
- USDA Agricultural Research Service, Invasive Species and Pollinator Health, Albany, CA
| | - Tom Royer
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK
| | - C Jack Deloach
- USDA Agricultural Research Service (Retired), Austin, TX
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Abstract
Interspecific hybridization is the process where closely related species mate and produce offspring with admixed genomes. The genomic revolution has shown that hybridization is common, and that it may represent an important source of novel variation. Although most interspecific hybrids are sterile or less fit than their parents, some may survive and reproduce, enabling the transfer of adaptive variants across the species boundary, and even result in the formation of novel evolutionary lineages. There are two main variants of hybrid species genomes: allopolyploid, which have one full chromosome set from each parent species, and homoploid, which are a mosaic of the parent species genomes with no increase in chromosome number. The establishment of hybrid species requires the development of reproductive isolation against parental species. Allopolyploid species often have strong intrinsic reproductive barriers due to differences in chromosome number, and homoploid hybrids can become reproductively isolated from the parent species through assortment of genetic incompatibilities. However, both types of hybrids can become further reproductively isolated, gaining extrinsic isolation barriers, by exploiting novel ecological niches, relative to their parents. Hybrids represent the merging of divergent genomes and thus face problems arising from incompatible combinations of genes. Thus hybrid genomes are highly dynamic and undergo rapid evolutionary change, including genome stabilization in which selection against incompatible combinations results in fixation of compatible ancestry block combinations within the hybrid species. The potential for rapid adaptation or speciation makes hybrid genomes a particularly exciting subject of in evolutionary biology. Here we summarize how introgressed alleles or hybrid species can establish and how the resulting hybrid genomes evolve.
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Affiliation(s)
- Anna Runemark
- Department of Biology, Lund University, Lund, Sweden
- * E-mail:
| | - Mario Vallejo-Marin
- Biological and Environmental Sciences, University of Stirling, Stirling, Scotland, United Kingdom
| | - Joana I. Meier
- St John's College, Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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38
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Servedio MR, Hermisson J. The evolution of partial reproductive isolation as an adaptive optimum. Evolution 2019; 74:4-14. [DOI: 10.1111/evo.13880] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/07/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Maria R. Servedio
- Department of Biology University of North Carolina Chapel Hill North Carolina 27599
| | - Joachim Hermisson
- Mathematics and BioSciences Group, Faculty of Mathematics and Max F. Perutz Laboratories University of Vienna Vienna Austria
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Abstract
Microsatellites are repetitive DNA sequences usually found in non-coding regions of the genome. Their quantification and analysis have applications in fields from population genetics to evolutionary biology. As genome assemblies become commonplace, the need for software that can facilitate analyses has never been greater. In particular, R packages that can analyze genomic data are particularly important since this is one of the most popular software environments for biologists. We created an R package, micRocounter, to quantify microsatellites. We have optimized our package for speed, accessibility, and portability, making the automated analysis of large genomic data sets feasible. Computationally intensive algorithms were built in C++ to increase speed. Tests using benchmark datasets show a 200-fold improvement in speed over existing software. A moderately sized genome of 500 Mb can be processed in under 50 sec. Results are output as an object in R increasing accessibility and flexibility for practitioners.
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Marques DA, Meier JI, Seehausen O. A Combinatorial View on Speciation and Adaptive Radiation. Trends Ecol Evol 2019; 34:531-544. [DOI: 10.1016/j.tree.2019.02.008] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 02/07/2019] [Accepted: 02/13/2019] [Indexed: 01/28/2023]
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Caspase-8-dependent control of NK- and T cell responses during cytomegalovirus infection. Med Microbiol Immunol 2019; 208:555-571. [PMID: 31098689 DOI: 10.1007/s00430-019-00616-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 04/17/2019] [Indexed: 12/26/2022]
Abstract
Caspase-8 (CASP8) impacts antiviral immunity in expected as well as unexpected ways. Mice with combined deficiency in CASP8 and RIPK3 cannot support extrinsic apoptosis or RIPK3-dependent programmed necrosis, enabling studies of CASP8 function without complications of unleashed necroptosis. These extrinsic cell death pathways are naturally targeted by murine cytomegalovirus (MCMV)-encoded cell death suppressors, showing they are key to cell-autonomous host defense. Remarkably, Casp8-/-Ripk3-/-, Ripk1-/-Casp8-/-Ripk3-/- and Casp8-/-Ripk3K51A/K51A mice mount robust antiviral T cell responses to control MCMV infection. Studies in Casp8-/-Ripk3-/- mice show that CASP8 restrains expansion of MCMV-specific natural killer (NK) and CD8 T cells without compromising contraction or immune memory. Infected Casp8-/-Ripk3-/- or Casp8-/-Ripk3K51A/K51A mice have higher levels of virus-specific NK cells and CD8 T cells compared to matched RIPK3-deficient littermates or WT mice. CASP8, likely acting downstream of Fas death receptor, dampens proliferation of CD8 T cells during expansion. Importantly, contraction proceeds unimpaired in the absence of extrinsic death pathways owing to intact Bim-dependent (intrinsic) apoptosis. CD8 T cell memory develops in Casp8-/-Ripk3-/- mice, but memory inflation characteristic of MCMV infection is not sustained in the absence of CASP8 function. Despite this, Casp8-/-Ripk3-/- mice are immune to secondary challenge. Interferon (IFN)γ is recognized as a key cytokine for adaptive immune control of MCMV. Ifngr-/-Casp8-/-Ripk3-/- mice exhibit increased lifelong persistence in salivary glands as well as lungs compared to Ifngr-/- and Casp8-/-Ripk3-/- mice. Thus, mice deficient in CASP8 and RIPK3 are more dependent on IFNγ mechanisms for sustained T cell immune control of MCMV. Overall, appropriate NK- and T cell immunity to MCMV is dependent on host CASP8 function independent of RIPK3-regulated pathways.
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42
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Yang Y, Blomenkamp S, Dugas MB, Richards-Zawacki CL, Pröhl H. Mate Choice versus Mate Preference: Inferences about Color-Assortative Mating Differ between Field and Lab Assays of Poison Frog Behavior. Am Nat 2019; 193:598-607. [PMID: 30912970 DOI: 10.1086/702249] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Codivergence of mating traits and mate preferences can lead to behavioral isolation among lineages in early stages of speciation. However, mate preferences limit gene flow only when expressed as mate choice, and numerous factors might be more important than preferences in nature. In the extremely color polytypic strawberry poison frog (Oophaga pumilio), female mate preferences have codiverged with color in most allopatric populations tested. Whether these lab-assayed preferences predict mating (gene flow) in the wild remains unclear. We observed courting pairs in a natural contact zone between red and blue lineages until oviposition or courtship termination. We found color-assortative mating in a disturbed habitat with high population density but not in a secondary forest with lower density. Our results suggest color-assortative O. pumilio mate choice in the wild but also mating patterns that do not match those predicted by lab-assayed preferences.
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43
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Taylor SA, Larson EL. Insights from genomes into the evolutionary importance and prevalence of hybridization in nature. Nat Ecol Evol 2019; 3:170-177. [DOI: 10.1038/s41559-018-0777-y] [Citation(s) in RCA: 211] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 12/04/2018] [Indexed: 01/27/2023]
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Lenart P, Bienertová-Vašků J, Berec L. Evolution favours aging in populations with assortative mating and in sexually dimorphic populations. Sci Rep 2018; 8:16072. [PMID: 30375446 PMCID: PMC6207771 DOI: 10.1038/s41598-018-34391-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 10/17/2018] [Indexed: 01/27/2023] Open
Abstract
Since aging seems omnipresent, many authors regard it as an inevitable consequence of the laws of physics. However, recent research has conclusively shown that some organisms do not age, or at least do not age on a scale comparable with other aging organisms. This begets the question why aging evolved in some organisms yet not in others. Here we present a simulation model of competition between aging and non-aging individuals in a sexually reproducing population. We find that the aging individuals may outcompete the non-aging ones if they have a sufficiently but not excessively higher initial fecundity or if individuals mate assortatively with respect to their own phenotype. Furthermore, the aging phenotype outcompetes the non-aging one or resists dominance of the latter for a longer period in populations composed of genuine males and females compared to populations of simultaneous hermaphrodites. Finally, whereas sterilizing parasites promote non-aging, the effect of mortality-enhancing parasites is to enable longer persistence of the aging phenotype relative to when parasites are absent. Since the aging individuals replace the non-aging ones in diverse scenarios commonly found in nature, our study provides important insights into why aging has evolved in most, but not all organisms.
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Affiliation(s)
- Peter Lenart
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A18, 625 00, Brno, Czech Republic
- Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 5, Building A29, 625 00, Brno, Czech Republic
| | - Julie Bienertová-Vašků
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A18, 625 00, Brno, Czech Republic
- Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 5, Building A29, 625 00, Brno, Czech Republic
| | - Luděk Berec
- Centre for Mathematical Biology, Institute of Mathematics, Faculty of Science, University of South Bohemia, Branišovská 1760, 37005, České Budějovice, Czech Republic.
- Czech Academy of Sciences, Biology Centre, Institute of Entomology, Department of Ecology, Branišovská 31, 37005, České Budějovice, Czech Republic.
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45
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Role of sexual imprinting in assortative mating and premating isolation in Darwin's finches. Proc Natl Acad Sci U S A 2018; 115:E10879-E10887. [PMID: 30348758 DOI: 10.1073/pnas.1813662115] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Global biodiversity is being degraded at an unprecedented rate, so it is important to preserve the potential for future speciation. Providing for the future requires understanding speciation as a contemporary ecological process. Phylogenetically young adaptive radiations are a good choice for detailed study because diversification is ongoing. A key question is how incipient species become reproductively isolated from each other. Barriers to gene exchange have been investigated experimentally in the laboratory and in the field, but little information exists from the quantitative study of mating patterns in nature. Although the degree to which genetic variation underlying mate-preference learning is unknown, we provide evidence that two species of Darwin's finches imprint on morphological cues of their parents and mate assortatively. Statistical evidence of presumed imprinting is stronger for sons than for daughters and is stronger for imprinting on fathers than on mothers. In combination, morphology and species-specific song learned from the father constitute a barrier to interbreeding. The barrier becomes stronger the more the species diverge morphologically and ecologically. It occasionally breaks down, and the species hybridize. Hybridization is most likely to happen when species are similar to each other in adaptive morphological traits, e.g., body size and beak size and shape. Hybridization can lead to the formation of a new species reproductively isolated from the parental species as a result of sexual imprinting. Conservation of sufficiently diverse natural habitat is needed to sustain a large sample of extant biota and preserve the potential for future speciation.
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46
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Beckman EJ, Benham PM, Cheviron ZA, Witt C. Detecting introgression despite phylogenetic uncertainty: The case of the South American siskins. Mol Ecol 2018; 27:4350-4367. [DOI: 10.1111/mec.14795] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 05/21/2018] [Accepted: 05/23/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Elizabeth J. Beckman
- Division of Biological Sciences University of Montana Missoula Montana
- Department of Biology and Museum of Southwestern Biology University of New Mexico Albuquerque New Mexico
| | - Phred M. Benham
- Division of Biological Sciences University of Montana Missoula Montana
| | | | - Christopher C. Witt
- Department of Biology and Museum of Southwestern Biology University of New Mexico Albuquerque New Mexico
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47
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Au KLE. Digest: The evolution of sexual imprinting as an assortative mating mechanism. Evolution 2018; 72:1529-1530. [PMID: 29920665 DOI: 10.1111/evo.13527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 06/08/2018] [Indexed: 11/30/2022]
Abstract
In this issue, Yeh et al. (2018) investigated whether sexual imprinting could act as an assortative mating mechanism, reducing hybridization and increasing premating isolation. While they indeed find that imprinting leads to assortative mating and reduced hybridization, the strength at which imprinting evolves is usually intermediate, because it is counterbalanced by the costs of imprinting and the benefits of adaptive hybridization. Thus, while sexual imprinting can act as an assortative mating mechanism, it is often not the sole element of female mate choice.
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Affiliation(s)
- Kwan Lung Elroy Au
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, Australia
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48
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Schumer M, Xu C, Powell DL, Durvasula A, Skov L, Holland C, Blazier JC, Sankararaman S, Andolfatto P, Rosenthal GG, Przeworski M. Natural selection interacts with recombination to shape the evolution of hybrid genomes. Science 2018; 360:656-660. [PMID: 29674434 PMCID: PMC6069607 DOI: 10.1126/science.aar3684] [Citation(s) in RCA: 229] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 03/23/2018] [Indexed: 12/29/2022]
Abstract
To investigate the consequences of hybridization between species, we studied three replicate hybrid populations that formed naturally between two swordtail fish species, estimating their fine-scale genetic map and inferring ancestry along the genomes of 690 individuals. In all three populations, ancestry from the "minor" parental species is more common in regions of high recombination and where there is linkage to fewer putative targets of selection. The same patterns are apparent in a reanalysis of human and archaic admixture. These results support models in which ancestry from the minor parental species is more likely to persist when rapidly uncoupled from alleles that are deleterious in hybrids. Our analyses further indicate that selection on swordtail hybrids stems predominantly from deleterious combinations of epistatically interacting alleles.
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Affiliation(s)
- Molly Schumer
- Howard Hughes Medical Institute (HHMI), Boston, MA, USA.
- Harvard Society of Fellows, Harvard University, Cambridge, MA, USA
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
| | - Chenling Xu
- Center for Computational Biology, University of California at Berkeley, Berkeley, CA, USA
| | - Daniel L Powell
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Arun Durvasula
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Laurits Skov
- Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
| | - Chris Holland
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - John C Blazier
- Department of Biology, Texas A&M University, College Station, TX, USA
- Texas A&M Institute for Genome Sciences and Society, College Station, TX, USA
| | - Sriram Sankararaman
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Computer Science, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peter Andolfatto
- Department of Ecology and Evolutionary Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Gil G Rosenthal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Molly Przeworski
- Department of Biological Sciences, Columbia University, New York, NY, USA.
- Department of Systems Biology, Columbia University, New York, NY, USA
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49
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Zimmer C, Riesch R, Jourdan J, Bierbach D, Arias-Rodriguez L, Plath M. Female Choice Undermines the Emergence of Strong Sexual Isolation between Locally Adapted Populations of Atlantic Mollies ( Poecilia mexicana). Genes (Basel) 2018; 9:E232. [PMID: 29724050 PMCID: PMC5977172 DOI: 10.3390/genes9050232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/23/2018] [Accepted: 04/25/2018] [Indexed: 11/16/2022] Open
Abstract
Divergent selection between ecologically dissimilar habitats promotes local adaptation, which can lead to reproductive isolation (RI). Populations in the Poecilia mexicana species complex have independently adapted to toxic hydrogen sulfide and show varying degrees of RI. Here, we examined the variation in the mate choice component of prezygotic RI. Mate choice tests across drainages (with stimulus males from another drainage) suggest that specific features of the males coupled with a general female preference for yellow color patterns explain the observed variation. Analyses of male body coloration identified the intensity of yellow fin coloration as a strong candidate to explain this pattern, and common-garden rearing suggested heritable population differences. Male sexual ornamentation apparently evolved differently across sulfide-adapted populations, for example because of differences in natural counterselection via predation. The ubiquitous preference for yellow color ornaments in poeciliid females likely undermines the emergence of strong RI, as female discrimination in favor of own males becomes weaker when yellow fin coloration in the respective sulfide ecotype increases. Our study illustrates the complexity of the (partly non-parallel) pathways to divergence among replicated ecological gradients. We suggest that future work should identify the genomic loci involved in the pattern reported here, making use of the increasing genomic and transcriptomic datasets available for our study system.
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Affiliation(s)
- Claudia Zimmer
- College of Animal Science & Technology, Northwest A&F University, Yangling 712100, China.
- Department of Ecology and Evolution, Goethe University of Frankfurt, Max-von-Laue-Straße 13, D-60438 Frankfurt am Main, Germany.
| | - Rüdiger Riesch
- Centre for Ecology, Evolution and Behaviour, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK.
| | - Jonas Jourdan
- Department of River Ecology and Conservation, Senckenberg Research Institute and Natural History Museum Frankfurt, D-63571 Gelnhausen, Germany.
| | - David Bierbach
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, D-12587 Berlin, Germany.
| | - Lenin Arias-Rodriguez
- División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco (UJAT), 86150 Villahermosa, Tabasco, Mexico.
| | - Martin Plath
- College of Animal Science & Technology, Northwest A&F University, Yangling 712100, China.
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A&F University, Yangling 712100, China.
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