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Fouqueau L, Polechová J. Eco-evolutionary dynamics in changing environments: integrating theory with data. J Evol Biol 2024; 37:579-587. [PMID: 38941551 DOI: 10.1093/jeb/voae067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 05/23/2024] [Accepted: 05/31/2024] [Indexed: 06/30/2024]
Affiliation(s)
- Louise Fouqueau
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jitka Polechová
- Department of Mathematics, University of Vienna, Vienna, Austria
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2
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Bruni G, Chiocchio A, Nascetti G, Cimmaruta R. Different patterns of introgression in a three species hybrid zone among European cave salamanders. Ecol Evol 2023; 13:e10437. [PMID: 37636870 PMCID: PMC10447881 DOI: 10.1002/ece3.10437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 08/29/2023] Open
Abstract
Hybrid zones occur where genetically distinct populations meet, mate and produce offspring with mixed ancestry. In Plethodontid salamanders, introgressive hybridization is a common phenomenon, where hybrids backcross with parental populations leading to the spread of new alleles into the parental genomes. Whereas many hybrid zones have been reported in American Plethodontid salamanders, only a single hybrid zone has been documented in European plethodontids so far, which is located at the Apuan Alps in the Italian Peninsula. Here, we describe a previously unreported hybrid zone in the Northern Apennines involving all the three Plethodontid salamander species inhabiting the Italian Peninsula. We found 21 new Speleomantes sites of occurrence, from a hitherto unexplored area located at the boundaries between three Speleomantes species ranges. Using mitochondrial (Cytb and ND2 genes) and nuclear markers (two diagnostic SNPs at the NCX1 gene), we revealed a three-way contact zone where all the three mainland species hybridize: S. strinatii, S. ambrosii and S. italicus. We observed a strong mitonuclear discordance, with mitochondrial markers showing a conspicuous geographic pattern, while diagnostic nuclear SNPs coexisted in both the same populations and individuals, providing evidence of hybridization in many possible combinations. The introgression is asymmetric, with S. italicus mitogenome usually associated with S. a. ambrosii and, to a lesser extent, to S. strinatii nuclear alleles. This finding confirms that Plethodontid are a group of choice to investigate hybridization mechanisms and suggests that behavioural, genetic and ecological components may concur in determining the direction and extent of introgression.
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Affiliation(s)
| | - Andrea Chiocchio
- Department of Ecological and Biological SciencesTuscia UniversityViterboItaly
| | - Giuseppe Nascetti
- Department of Ecological and Biological SciencesTuscia UniversityViterboItaly
| | - Roberta Cimmaruta
- Department of Ecological and Biological SciencesTuscia UniversityViterboItaly
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3
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Irregularities in Meiotic Prophase I as Prerequisites for Reproductive Isolation in Experimental Hybrids Carrying Robertsonian Translocations. DIVERSITY 2023. [DOI: 10.3390/d15030364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The basic causes of postzygotic isolation can be elucidated if gametogenesis is studied, which is a drastically different process in males and females. As a step toward clarifying this problem, we obtained an experimental inbred lineage of the eastern mole vole Ellobius tancrei, whose founder animals were animals with identical diploid numbers 2n = 50 but with different Robertsonian translocations (Rb), namely 2Rb4.12 and 2Rb9.13 in the female and 2Rb.2.18 and 2Rb5.9 in the male. Here, we analyzed strictly inbred hybrids (F1, fertile and F10, sterile) using immunocytochemical methods in order to study spermatocytes during the meiotic prophase I. Previously, the presence of trivalents was assumed to have no significant effect on spermatogenesis and fertility in hybrids, but we demonstrated that spermatogenesis might be disturbed due to the cumulative effects of the retarded synapses of Rb bivalents as well as trivalents and their associations with XX sex bivalents. Alterations in the number of gametes due to the described processes led to a decrease in reproductive capacity up to sterility and can be examined as a mechanism for reproductive isolation, thus starting speciation.
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4
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Gaczorek TS, Marszałek M, Dudek K, Arntzen JW, Wielstra B, Babik W. Interspecific introgression of MHC genes in Triturus newts: Evidence from multiple contact zones. Mol Ecol 2023; 32:867-880. [PMID: 36458894 PMCID: PMC10108261 DOI: 10.1111/mec.16804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 11/03/2022] [Accepted: 11/29/2022] [Indexed: 12/04/2022]
Abstract
The major histocompatibility complex (MHC) genes are central to the adaptive immune response in vertebrates. Selection generally maintains high MHC variation because the spectrum of recognized pathogens depends on MHC polymorphism. Novel alleles favoured by selection originate by interallelic recombination or de novo mutations but may also be acquired by introgression from related species. However, the extent and prevalence of MHC introgression remain an open question. In this study, we tested for MHC introgression in six hybrid zones formed by six Triturus newt species. We sequenced and genotyped the polymorphic second exons of the MHC class I and II genes and compared their interspecific similarity at various distances from the centre of the hybrid zone. We found evidence for introgression of both MHC classes in the majority of examined hybrid zones, with support for a more substantial class I introgression. Furthermore, the overall MHC allele sharing outside of hybrid zones was elevated between pairs of Triturus species with abutting ranges, regardless of the phylogenetic distance between them. No effect of past hybrid zone movement on MHC allele sharing was found. Finally, using previously published genome-wide data, we demonstrated that MHC introgression was more extensive than genome-wide introgression, supporting its adaptive potential. Our study thus provides evidence for the prevalence of MHC introgression across multiple Triturus hybrid zones, indicating that MHC introgression between divergent hybridizing species may be widespread and adaptive.
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Affiliation(s)
- Tomasz S Gaczorek
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Marzena Marszałek
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Katarzyna Dudek
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Jan W Arntzen
- Naturalis Biodiversity Center, Leiden, The Netherlands.,Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Ben Wielstra
- Naturalis Biodiversity Center, Leiden, The Netherlands.,Institute of Biology, Leiden University, Leiden, The Netherlands
| | - Wiesław Babik
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
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5
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Mallet J, Mullen SP. Reproductive isolation is a heuristic, not a measure: a commentary on Westram et al., 2022. J Evol Biol 2022; 35:1175-1182. [PMID: 36063161 DOI: 10.1111/jeb.14052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 12/17/2022]
Abstract
Reproductive isolation is the heuristic basis of the biological species concept, but what is it? Westram et al. (this issue) propose that it is a measurable quantity, "barrier strength," that prevents gene flow among populations. However, their attempt to make the concept of reproductive isolation more scientific is unlikely to satisfy the diverse opinions of all evolutionary biologists. There are many different opinions about the nature of species, even under the biological species concept. Complete reproductive isolation, where gene flow is effectively zero, is regarded by some biologists as an important end point of speciation. Others, including Westram et al., argue for a more nuanced approach, and they also suggest that reproductive isolation may differ in different parts of the genome due to variation in genetic linkage to divergently selected loci. In contrast to both these approaches, we favour as a key criterion of speciation the stable coexistence of divergent populations in sympatry. Obviously, such populations must be reproductively isolated in some sense, but neither the fraction of the genome that is exchanged, nor measures of overall barrier strength acting on neutral variation will yield very precise predictions as to species status. Although an overall measure of reproductive isolation is virtually unattainable for these reasons, its early generation components, such as assortative mating, divergent selection, or hybrid inviability and sterility are readily measurable and remain informative. For example, we can make the prediction that to remain divergent in sympatry, almost all sexual species will require strong assortative mating, as well as some sort of ecological or intrinsic selection against hybrids and introgressed variants.
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Affiliation(s)
- James Mallet
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Sean P Mullen
- Department of Biology, Boston University, Boston, Massachusetts, USA
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6
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The historical nature of biological complexity and the ineffectiveness of the mathematical approach to it. Theory Biosci 2022; 141:213-231. [PMID: 35583727 PMCID: PMC9184406 DOI: 10.1007/s12064-022-00369-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 04/12/2022] [Indexed: 11/29/2022]
Abstract
Contemporary scientific knowledge is built on both methodological and epistemological reductionism. The discovery of the limitations of the reductionist paradigm in the mathematical treatment of certain physical phenomena originated the notion of complexity, both as a pattern and process. After clarifying some very general terms and ideas on biological evolution and biological complexity, the article will tackle to seek to summarize the debate on biological complexity and discuss the difference between complexities of living and inert matter. Some examples of the major successes of mathematics applied to biological problems will follow; the notion of an intrinsic limitation in the application of mathematics to biological complexity as a global, relational, and historical phenomenon at the individual and species level will also be advanced.
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7
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Buck R, Flores-Rentería L. The Syngameon Enigma. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11070895. [PMID: 35406874 PMCID: PMC9002738 DOI: 10.3390/plants11070895] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 05/17/2023]
Abstract
Despite their evolutionary relevance, multispecies networks or syngameons are rarely reported in the literature. Discovering how syngameons form and how they are maintained can give insight into processes such as adaptive radiations, island colonizations, and the creation of new hybrid lineages. Understanding these complex hybridization networks is even more pressing with anthropogenic climate change, as syngameons may have unique synergistic properties that will allow participating species to persist. The formation of a syngameon is not insurmountable, as several ways for a syngameon to form have been proposed, depending mostly on the magnitude and frequency of gene flow events, as well as the relatedness of its participants. Episodic hybridization with small amounts of introgression may keep syngameons stable and protect their participants from any detrimental effects of gene flow. As genomic sequencing becomes cheaper and more species are included in studies, the number of known syngameons is expected to increase. Syngameons must be considered in conservation efforts as the extinction of one participating species may have detrimental effects on the survival of all other species in the network.
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8
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Arntzen JW, Jehle R, Wielstra B. Genetic and morphological data demonstrate hybridization and backcrossing in a pair of salamanders at the far end of the speciation continuum. Evol Appl 2021; 14:2784-2793. [PMID: 34950229 PMCID: PMC8674889 DOI: 10.1111/eva.13312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 09/05/2021] [Accepted: 10/01/2021] [Indexed: 12/23/2022] Open
Abstract
Deeply diverged yet hybridizing species provide a system to investigate the final stages of the speciation process. We study a hybridizing pair of salamander species-the morphologically and genetically drastically different newts Triturus cristatus and T. marmoratus-with a panel of 32 nuclear and mitochondrial genetic markers. Morphologically identified hybrids are mostly of the F1 generation and mothered by T. cristatus. The sex ratio of the F1 hybrid class is reciprocally skewed, with a preponderance of females in T. cristatus-mothered hybrids and males in T. marmoratus-mothered hybrids. This amounts to the Haldane effect operating in one direction of the cross. Deeper generation hybrids are occasionally produced, possibly including F1 hybrid × backcross hybrid offspring. Interspecific gene flow is low, yet skewed toward T. cristatus. This asymmetry may be caused by hybrid zone movement, with the superseding species being predisposed to introgression. The persisting gene flow between deeply differentiated species supports the notion that full genetic isolation may be selected against. Conversely, published morphological data suggest that introgressive hybridization is detrimental, with digital malformations occurring more frequently in the area of sympatry. Finally, to assist field identification, both within the area of natural range overlap and concerning anthropogenic introductions elsewhere, we document the phenotypical variation of two generations of hybrids compared with both parental species. We suggest that fluctuating range boundaries, ecological segregation, cytonuclear incompatibilities and hybrid breakdown through Bateson-Dobzhansky-Muller incompatibilities all contribute to species integrity, despite incomplete isolation during secondary contact.
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Affiliation(s)
- Jan W. Arntzen
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of BiologyLeiden UniversityLeidenThe Netherlands
| | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
| | - Ben Wielstra
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of BiologyLeiden UniversityLeidenThe Netherlands
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9
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Abstract
Alleles that introgress between species can influence the evolutionary and ecological fate of species exposed to novel environments. Hybrid offspring of different species are often unfit, and yet it has long been argued that introgression can be a potent force in evolution, especially in plants. Over the last two decades, genomic data have increasingly provided evidence that introgression is a critically important source of genetic variation and that this additional variation can be useful in adaptive evolution of both animals and plants. Here, we review factors that influence the probability that foreign genetic variants provide long-term benefits (so-called adaptive introgression) and discuss their potential benefits. We find that introgression plays an important role in adaptive evolution, particularly when a species is far from its fitness optimum, such as when they expand their range or are subject to changing environments.
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Affiliation(s)
- Nathaniel B Edelman
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA; .,Current affiliation: Yale Institute for Biospheric Studies and Yale School of the Environment, Yale University, New Haven, Connecticut 06511, USA;
| | - James Mallet
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA;
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10
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Porter CK, Confer JL, Aldinger KR, Canterbury RA, Larkin JL, McNeil DJ. Strong yet incomplete reproductive isolation in Vermivora is not contradicted by other lines of evidence: A reply to Toews et al. Ecol Evol 2021; 11:10724-10730. [PMID: 34367609 PMCID: PMC8328446 DOI: 10.1002/ece3.7763] [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: 02/11/2021] [Revised: 05/14/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022] Open
Abstract
Toews et al. assert that strong reproductive isolation in Vermivora is inconsistent with other lines of evidence. Here, we discuss how strong yet incomplete reproductive isolation is consistent with other results from this system.
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Affiliation(s)
- Cody K. Porter
- Wildlife Biology ProgramLees‐McRae CollegeBanner ElkNCUSA
| | | | - Kyle R. Aldinger
- West Virginia Cooperative Fish and Wildlife Research UnitDivision of Forestry and Natural ResourcesWest Virginia UniversityMorgantownWVUSA
| | | | | | - Darin J. McNeil
- Department of EntomologyThe Pennsylvania State UniversityUniversity ParkPAUSA
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11
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Subramani T, Gunasagaran K, Natesan M. Genetic variability of Artemia franciscana populations from different salterns of southeast coast of India. Meta Gene 2021. [DOI: 10.1016/j.mgene.2021.100887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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12
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Stankowski S, Ravinet M. Defining the speciation continuum. Evolution 2021; 75:1256-1273. [PMID: 33754340 DOI: 10.1111/evo.14215] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 03/01/2021] [Accepted: 03/13/2021] [Indexed: 02/06/2023]
Abstract
A primary roadblock to our understanding of speciation is that it usually occurs over a timeframe that is too long to study from start to finish. The idea of a speciation continuum provides something of a solution to this problem; rather than observing the entire process, we can simply reconstruct it from the multitude of speciation events that surround us. But what do we really mean when we talk about the speciation continuum, and can it really help us understand speciation? We explored these questions using a literature review and online survey of speciation researchers. Although most researchers were familiar with the concept and thought it was useful, our survey revealed extensive disagreement about what the speciation continuum actually tells us. This is due partly to the lack of a clear definition. Here, we provide an explicit definition that is compatible with the Biological Species Concept. That is, the speciation continuum is a continuum of reproductive isolation. After outlining the logic of the definition in light of alternatives, we explain why attempts to reconstruct the speciation process from present-day populations will ultimately fail. We then outline how we think the speciation continuum concept can continue to act as a foundation for understanding the continuum of reproductive isolation that surrounds us.
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Affiliation(s)
- Sean Stankowski
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.,Current Address: Sean Stankowski, IST Austria, Klosterneuburg, 3400, Austria
| | - Mark Ravinet
- Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, 0316, Norway.,School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, United Kingdom
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13
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Ortego J, Gutiérrez-Rodríguez J, Noguerales V. Demographic consequences of dispersal-related trait shift in two recently diverged taxa of montane grasshoppers. Evolution 2021; 75:1998-2013. [PMID: 33646593 DOI: 10.1111/evo.14205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/03/2021] [Accepted: 02/17/2021] [Indexed: 12/19/2022]
Abstract
Although the pervasiveness of intraspecific wing-size polymorphism and transitions to flightlessness have long captivated biologists, the demographic outcomes of shifts in dispersal ability are not yet well understood and have been seldom studied at early stages of diversification. Here, we use genomic data to infer the consequences of dispersal-related trait variation in the taxonomically controversial short-winged (Chorthippus corsicus corsicus) and long-winged (Chorthippus corsicus pascuorum) Corsican grasshoppers. Our analyses revealed lack of contemporary hybridization between sympatric long- and short-winged forms and phylogenomic reconstructions supported their taxonomic distinctiveness, rejecting the hypothesis of intraspecific wing polymorphism. Statistical evaluation of alternative models of speciation strongly supported a scenario of Pleistocene divergence (<1.5 Ma) with ancestral gene flow. According to neutral expectations from differences in dispersal capacity, historical effective migration rates from the long- to the short-winged taxon were threefold higher than in the opposite direction. Although populations of the two taxa present a marked genetic structure and have experienced parallel demographic histories, our coalescent-based analyses suggest that reduced dispersal has fueled diversification in the short-winged C. c. corsicus. Collectively, our study illustrates how dispersal reduction can speed up geographical diversification and increase the opportunity for allopatric speciation in topographically complex landscapes.
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Affiliation(s)
- Joaquín Ortego
- Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), Seville, Spain
| | | | - Víctor Noguerales
- Island Ecology and Evolution Research Group, Institute of Natural Products and Agrobiology (IPNA-CSIC), La Laguna, Tenerife, Canarias, Spain
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14
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Kulmuni J, Butlin RK, Lucek K, Savolainen V, Westram AM. Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190528. [PMID: 32654637 PMCID: PMC7423269 DOI: 10.1098/rstb.2019.0528] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2020] [Indexed: 12/12/2022] Open
Abstract
Speciation, that is, the evolution of reproductive barriers eventually leading to complete isolation, is a crucial process generating biodiversity. Recent work has contributed much to our understanding of how reproductive barriers begin to evolve, and how they are maintained in the face of gene flow. However, little is known about the transition from partial to strong reproductive isolation (RI) and the completion of speciation. We argue that the evolution of strong RI is likely to involve different processes, or new interactions among processes, compared with the evolution of the first reproductive barriers. Transition to strong RI may be brought about by changing external conditions, for example, following secondary contact. However, the increasing levels of RI themselves create opportunities for new barriers to evolve and, and interaction or coupling among barriers. These changing processes may depend on genomic architecture and leave detectable signals in the genome. We outline outstanding questions and suggest more theoretical and empirical work, considering both patterns and processes associated with strong RI, is needed to understand how speciation is completed. 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)
- Jonna Kulmuni
- Organismal and Evolutionary Biology, University of Helsinki, Finland
| | - Roger K. Butlin
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
- Department of Marine Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Kay Lucek
- Department of Environmental Sciences, University of Basel, 4056 Basel, Switzerland
| | - Vincent Savolainen
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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