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Xiong T, Mallet J. On the impermanence of species: The collapse of genetic incompatibilities in hybridizing populations. Evolution 2022; 76:2498-2512. [PMID: 36097352 PMCID: PMC9827863 DOI: 10.1111/evo.14626] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/23/2022] [Indexed: 01/22/2023]
Abstract
Species pairs often become genetically incompatible during divergence, which is an important source of reproductive isolation. An idealized picture is often painted where incompatibility alleles accumulate and fix between diverging species. However, recent studies have shown both that incompatibilities can collapse with ongoing hybridization, and that incompatibility loci can be polymorphic within species. This paper suggests some general rules for the behavior of incompatibilities under hybridization. In particular, we argue that redundancy of genetic pathways can strongly affect the dynamics of intrinsic incompatibilities. Since fitness in genetically redundant systems is unaffected by introducing a few foreign alleles, higher redundancy decreases the stability of incompatibilities during hybridization, but also increases tolerance of incompatibility polymorphism within species. We use simulations and theories to show that this principle leads to two types of collapse: in redundant systems, exemplified by classical Dobzhansky-Muller incompatibilities, collapse is continuous and approaches a quasi-neutral polymorphism between broadly sympatric species, often as a result of isolation-by-distance. In nonredundant systems, exemplified by co-evolution among genetic elements, incompatibilities are often stable, but can collapse abruptly with spatial traveling waves. As both types are common, the proposed principle may be useful in understanding the abundance of genetic incompatibilities in natural populations.
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Affiliation(s)
- Tianzhu Xiong
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMA02138USA
| | - James Mallet
- Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeMA02138USA
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Westram AM, Stankowski S, Surendranadh P, Barton N. What is reproductive isolation? J Evol Biol 2022; 35:1143-1164. [PMID: 36063156 PMCID: PMC9542822 DOI: 10.1111/jeb.14005] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/18/2022] [Accepted: 02/23/2022] [Indexed: 12/12/2022]
Abstract
Reproductive isolation (RI) is a core concept in evolutionary biology. It has been the central focus of speciation research since the modern synthesis and is the basis by which biological species are defined. Despite this, the term is used in seemingly different ways, and attempts to quantify RI have used very different approaches. After showing that the field lacks a clear definition of the term, we attempt to clarify key issues, including what RI is, how it can be quantified in principle, and how it can be measured in practice. Following other definitions with a genetic focus, we propose that RI is a quantitative measure of the effect that genetic differences between populations have on gene flow. Specifically, RI compares the flow of neutral alleles in the presence of these genetic differences to the flow without any such differences. RI is thus greater than zero when genetic differences between populations reduce the flow of neutral alleles between populations. We show how RI can be quantified in a range of scenarios. A key conclusion is that RI depends strongly on circumstances-including the spatial, temporal and genomic context-making it difficult to compare across systems. After reviewing methods for estimating RI from data, we conclude that it is difficult to measure in practice. We discuss our findings in light of the goals of speciation research and encourage the use of methods for estimating RI that integrate organismal and genetic approaches.
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Affiliation(s)
- Anja M. Westram
- IST AustriaKlosterneuburgAustria
- Faculty of Biosciences and AquacultureNord UniversityBodøNorway
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Westram AM, Stankowski S, Surendranadh P, Barton NH. Reproductive isolation, speciation, and the value of disagreement: A reply to the commentaries on 'What is reproductive isolation?'. J Evol Biol 2022; 35:1200-1205. [PMID: 36063160 PMCID: PMC9542782 DOI: 10.1111/jeb.14082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 08/05/2022] [Indexed: 01/06/2023]
Affiliation(s)
- Anja M Westram
- Insitute of Science and Technology Austria (ISTA), Klosterneuburg, Austria.,Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Sean Stankowski
- Insitute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | | | - Nicholas H Barton
- Insitute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
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Meier JI, Salazar PA, Kučka M, Davies RW, Dréau A, Aldás I, Box Power O, Nadeau NJ, Bridle JR, Rolian C, Barton NH, McMillan WO, Jiggins CD, Chan YF. Haplotype tagging reveals parallel formation of hybrid races in two butterfly species. Proc Natl Acad Sci U S A 2021; 118:e2015005118. [PMID: 34155138 PMCID: PMC8237668 DOI: 10.1073/pnas.2015005118] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genetic variation segregates as linked sets of variants or haplotypes. Haplotypes and linkage are central to genetics and underpin virtually all genetic and selection analysis. Yet, genomic data often omit haplotype information due to constraints in sequencing technologies. Here, we present "haplotagging," a simple, low-cost linked-read sequencing technique that allows sequencing of hundreds of individuals while retaining linkage information. We apply haplotagging to construct megabase-size haplotypes for over 600 individual butterflies (Heliconius erato and H. melpomene), which form overlapping hybrid zones across an elevational gradient in Ecuador. Haplotagging identifies loci controlling distinctive high- and lowland wing color patterns. Divergent haplotypes are found at the same major loci in both species, while chromosome rearrangements show no parallelism. Remarkably, in both species, the geographic clines for the major wing-pattern loci are displaced by 18 km, leading to the rise of a novel hybrid morph in the center of the hybrid zone. We propose that shared warning signaling (Müllerian mimicry) may couple the cline shifts seen in both species and facilitate the parallel coemergence of a novel hybrid morph in both comimetic species. Our results show the power of efficient haplotyping methods when combined with large-scale sequencing data from natural populations.
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Affiliation(s)
- Joana I Meier
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
- St. John's College, University of Cambridge, Cambridge CB2 1TP, United Kingdom
| | - Patricio A Salazar
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Marek Kučka
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | | | - Andreea Dréau
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany
| | | | - Olivia Box Power
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Nicola J Nadeau
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Jon R Bridle
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Campbell Rolian
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Nicholas H Barton
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Panamá, Apartado Postal 0843-00153, República de Panamá
| | - Chris D Jiggins
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom;
- Smithsonian Tropical Research Institute, Panamá, Apartado Postal 0843-00153, República de Panamá
| | - Yingguang Frank Chan
- Friedrich Miescher Laboratory of the Max Planck Society, 72076 Tübingen, Germany;
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Parris MJ. HYBRIDIZATION IN LEOPARD FROGS (
RANA PIPIENS
COMPLEX): LARVAL FITNESS COMPONENTS IN SINGLE‐GENOTYPE POPULATIONS AND MIXTURES. Evolution 2017; 53:1872-1883. [DOI: 10.1111/j.1558-5646.1999.tb04569.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/1998] [Accepted: 05/21/1999] [Indexed: 11/26/2022]
Affiliation(s)
- Matthew J. Parris
- Division of Biological Sciences, 105 Tucker Hall University of Missouri Columbia Missouri 65211‐7400
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Gündüz I, Pollock CL, Giménez MD, Förster DW, White TA, Sans-Fuentes MA, Hauffe HC, Ventura J, López-Fuster MJ, Searle JB. Staggered chromosomal hybrid zones in the house mouse: relevance to reticulate evolution and speciation. Genes (Basel) 2010; 1:193-209. [PMID: 24710041 PMCID: PMC3954089 DOI: 10.3390/genes1020193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/05/2010] [Accepted: 07/08/2010] [Indexed: 01/14/2023] Open
Abstract
In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed 'zonal raciation'). In this way they can add to the total 'stock' of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event.
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Affiliation(s)
- Islam Gündüz
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
| | | | - Mabel D Giménez
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
| | - Daniel W Förster
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
| | - Thomas A White
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK.
| | - Maria A Sans-Fuentes
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
| | - Heidi C Hauffe
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
| | - Jacint Ventura
- Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia, Facultat de Biociènces, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - María José López-Fuster
- Departament de Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028 Barcelona, Spain.
| | - Jeremy B Searle
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
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Sites JW, Barton NH, Reed KM. THE GENETIC STRUCTURE OF A HYBRID ZONE BETWEEN TWO CHROMOSOME RACES OF THE
SCELOPORUS GRAMMICUS
COMPLEX (SAURIA, PHRYNOSOMATIDAE) IN CENTRAL MEXICO. Evolution 1995; 49:9-36. [DOI: 10.1111/j.1558-5646.1995.tb05955.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/1993] [Accepted: 05/27/1994] [Indexed: 11/30/2022]
Affiliation(s)
- Jack W. Sites
- Department of Zoology Brigham Young University Provo Utah 84602
| | - Nicholas H. Barton
- Division of Biology University of Edinburgh King's Buildings Edinburgh EH9 3JT United Kingdom
| | - Kent M. Reed
- Department of Biology Texas A & M University College Station Texas 77843
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