1
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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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2
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Sotola VA, Berg CS, Samuli M, Chen H, Mantel SJ, Beardsley PA, Yuan YW, Sweigart AL, Fishman L. Genomic mechanisms and consequences of diverse postzygotic barriers between monkeyflower species. Genetics 2023; 225:iyad156. [PMID: 37603838 DOI: 10.1093/genetics/iyad156] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/15/2023] [Accepted: 07/18/2023] [Indexed: 08/23/2023] Open
Abstract
The evolution of genomic incompatibilities causing postzygotic barriers to hybridization is a key step in species divergence. Incompatibilities take 2 general forms-structural divergence between chromosomes leading to severe hybrid sterility in F1 hybrids and epistatic interactions between genes causing reduced fitness of hybrid gametes or zygotes (Dobzhansky-Muller incompatibilities). Despite substantial recent progress in understanding the molecular mechanisms and evolutionary origins of both types of incompatibility, how each behaves across multiple generations of hybridization remains relatively unexplored. Here, we use genetic mapping in F2 and recombinant inbred line (RIL) hybrid populations between the phenotypically divergent but naturally hybridizing monkeyflowers Mimulus cardinalis and M. parishii to characterize the genetic basis of hybrid incompatibility and examine its changing effects over multiple generations of experimental hybridization. In F2s, we found severe hybrid pollen inviability (<50% reduction vs parental genotypes) and pseudolinkage caused by a reciprocal translocation between Chromosomes 6 and 7 in the parental species. RILs retained excess heterozygosity around the translocation breakpoints, which caused substantial pollen inviability when interstitial crossovers had not created compatible heterokaryotypic configurations. Strong transmission ratio distortion and interchromosomal linkage disequilibrium in both F2s and RILs identified a novel 2-locus genic incompatibility causing sex-independent gametophytic (haploid) lethality. The latter interaction eliminated 3 of the expected 9 F2 genotypic classes via F1 gamete loss without detectable effects on the pollen number or viability of F2 double heterozygotes. Along with the mapping of numerous milder incompatibilities, these key findings illuminate the complex genetics of plant hybrid breakdown and are an important step toward understanding the genomic consequences of natural hybridization in this model system.
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Affiliation(s)
- V Alex Sotola
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Colette S Berg
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Matthew Samuli
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Hongfei Chen
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Samuel J Mantel
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Paul A Beardsley
- Department of Biological Sciences, California State Polytechnic University, Pomona, CA 91768, USA
| | - Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Andrea L Sweigart
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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3
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Lollar MJ, Biewer-Heisler TJ, Danen CE, Pool JE. Hybrid breakdown in male reproduction between recently diverged Drosophila melanogaster populations has a complex and variable genetic architecture. Evolution 2023; 77:1550-1563. [PMID: 37071601 PMCID: PMC10309968 DOI: 10.1093/evolut/qpad060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/15/2023] [Accepted: 04/14/2023] [Indexed: 04/19/2023]
Abstract
Secondary contact between formerly isolated populations may result in hybrid breakdown, in which untested allelic combinations in hybrids are maladaptive and limit genetic exchange. Studying early-stage reproductive isolation may yield key insights into the genetic architectures and evolutionary forces underlying the first steps toward speciation. Here, we leverage the recent worldwide expansion of Drosophila melanogaster to test for hybrid breakdown between populations that diverged within the last 13,000 years. We found clear evidence for hybrid breakdown in male reproduction, but not female reproduction or viability, supporting the prediction that hybrid breakdown affects the heterogametic sex first. The frequency of non-reproducing F2 males varied among different crosses involving the same southern African and European populations, as did the qualitative effect of cross direction, implying a genetically variable basis of hybrid breakdown and a role for uniparentally inherited factors. The levels of breakdown observed in F2 males were not recapitulated in backcrossed individuals, consistent with the existence of incompatibilities with at least three partners. Thus, some of the very first steps toward reproductive isolation could involve incompatibilities with complex and variable genetic architectures. Collectively, our findings emphasize this system's potential for future studies on the genetic and organismal basis of early-stage reproductive isolation.
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Affiliation(s)
- Matthew J Lollar
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | | | - Clarice E Danen
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - John E Pool
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, United States
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4
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Alexander A, Robbins MB, Holmes J, Moyle RG, Peterson AT. Limited movement of an avian hybrid zone in relation to regional variation in magnitude of climate change. Mol Ecol 2022; 31:6634-6648. [PMID: 36210655 PMCID: PMC9729445 DOI: 10.1111/mec.16727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 01/13/2023]
Abstract
Studies of natural hybrid zones can provide documentation of range shifts in response to climate change and identify loci important to reproductive isolation. Using a temporal (36-38 years) comparison of the black-capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee hybrid zone, we investigated movement of the western portion of the zone (western Missouri) and assessed whether loci and pathways underpinning reproductive isolation were similar to those in the eastern portion of the hybrid zone. Using 92 birds sampled along the hybrid zone transect in 2016 and 68 birds sampled between 1978 and 1980, we generated 11,669 SNPs via ddRADseq. These SNPs were used to assess movement of the hybrid zone through time and to evaluate variation in introgression among loci. We demonstrate that the interface has moved ~5 km to the northwest over the last 36-38 years, that is, at only one-fifth the rate at which the eastern portion (e.g., Pennsylvania, Ohio) of the hybrid zone has moved. Temperature trends over the last 38 years reveal that eastern areas have warmed 50% more than western areas in terms of annual mean temperature, possibly providing an explanation for the slower movement of the hybrid zone in Missouri. Our results suggest hybrid zone movement in broadly distributed species, such as chickadees, will vary between areas in response to local differences in the impacts of climate change.
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Affiliation(s)
- Alana Alexander
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Anatomy, University of Otago, Dunedin 9016, New Zealand.,Corresponding author.
| | - Mark B. Robbins
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA
| | - Jesse Holmes
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - Robert G. Moyle
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
| | - A. Townsend Peterson
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA
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5
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Watson ET, Flanagan BA, Pascar JA, Edmands S. Mitochondrial effects on fertility and longevity in Tigriopus californicus contradict predictions of the mother's curse hypothesis. Proc Biol Sci 2022; 289:20221211. [PMID: 36382523 PMCID: PMC9667352 DOI: 10.1098/rspb.2022.1211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/20/2022] [Indexed: 11/17/2022] Open
Abstract
Strict maternal inheritance of mitochondria favours the evolutionary accumulation of sex-biased fitness effects, as mitochondrial evolution occurs exclusively in female lineages. The 'mother's curse' hypothesis proposes that male-harming mutations should accumulate in mitochondrial genomes when they have neutral or beneficial effects on female fitness. Rigorous empirical tests have largely focused on Drosophila, where support for the predictions of mother's curse has been mixed. We investigated the impact of mother's curse mutations in Tigriopus californicus, a minute crustacean. Using non-recombinant backcrosses, we introgressed four divergent mitochondrial haplotypes into two nuclear backgrounds and recorded measures of fertility and longevity. We found that the phenotypic effects of mitochondrial mutations were context dependent, being influenced by the nuclear background in which they were expressed, as well as the sex of the individual and rearing temperature. Mitochondrial haplotype effects were greater for fertility than longevity, and temperature effects were greater for longevity. However, in opposition to mother's curse expectations, females had higher mitochondrial genetic variance than males for fertility and longevity, little evidence of sexual antagonism favouring females was found, and the impacts of mitonuclear mismatch harmed females but not males. Together, this indicates that selection on mitochondrial variation has not resulted in the accumulation of male mutation load in Tigriopus californicus.
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Affiliation(s)
- Eric T. Watson
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Jane A. Pascar
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
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6
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Burton RS. The role of mitonuclear incompatibilities in allopatric speciation. Cell Mol Life Sci 2022; 79:103. [PMID: 35091831 PMCID: PMC11072163 DOI: 10.1007/s00018-021-04059-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/19/2021] [Accepted: 11/25/2021] [Indexed: 11/03/2022]
Abstract
Aerobic metabolism in eukaryotic cells requires extensive interactions between products of the nuclear and mitochondrial genomes. Rapid evolution of the mitochondrial genome, including fixation of both adaptive and deleterious mutations, creates intrinsic selection pressures favoring nuclear gene mutations that maintain mitochondrial function. As this process occurs independently in allopatry, the resulting divergence between conspecific populations can subsequently be manifest in mitonuclear incompatibilities in inter-population hybrids. Such incompatibilities, mitonuclear versions of Bateson-Dobzhansky-Muller incompatibilities that form the standard model for allopatric speciation, can potentially restrict gene flow between populations, ultimately resulting in varying degrees of reproductive isolation. The potential role of mitonuclear incompatibilities in speciation is further enhanced where mtDNA substitution rates are elevated compared to the nuclear genome and where population structure maintains allopatry for adequate time to evolve multiple mitonuclear incompatibilities. However, the fact that mitochondrial introgression occurs across species boundaries has raised questions regarding the efficacy of mitonuclear incompatibilities in reducing gene flow. Several scenarios now appear to satisfactorily explain this phenomenon, including cases where differences in mtDNA genetic load may drive introgression or where co-introgression of coadapted nuclear genes may support the function of introgressed mtDNA. Although asymmetries in reproductive isolation between taxa are consistent with mitonuclear incompatibilities, interactions between autosomes and sex chromosomes yield similar predictions that are difficult to disentangle. With regard to establishing reproductive isolation while in allopatry, existing studies clearly suggest that mitonuclear incompatibilities can contribute to the evolution of barriers to gene flow. However, there is to date relatively little definitive evidence supporting a primary role for mitonuclear incompatibilities in the speciation process.
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Affiliation(s)
- Ronald S Burton
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093-0202, USA.
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7
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Říčan O, Říčanová Š, Almirón A, Casciotta J, Piálek L. Parallel evolution of a new sympatric species pair of
Crenicichla
(Teleostei: Cichlidae) from Misiones, Argentina with a review of biogeography and mitonuclear discordance in the
C. mandelburgeri
species complex. J ZOOL SYST EVOL RES 2021. [DOI: 10.1111/jzs.12566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Oldřich Říčan
- Faculty of Science Department of Zoology University of South Bohemia České Budějovice Czech Republic
| | - Štěpánka Říčanová
- Faculty of Science Department of Zoology University of South Bohemia České Budějovice Czech Republic
| | - Adriana Almirón
- Facultad de Ciencias Naturales y Museo División Zoología Vertebrados UNLP La Plata Argentina
| | - Jorge Casciotta
- Facultad de Ciencias Naturales y Museo División Zoología Vertebrados UNLP La Plata Argentina
- CIC, Comisión de Investigaciones Científicas de la Provincia de Buenos Aires Buenos Aires Argentina
| | - Lubomír Piálek
- Faculty of Science Department of Zoology University of South Bohemia České Budějovice Czech Republic
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8
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Grummer JA, Avila LJ, Morando MM, Leaché AD. Four Species Linked by Three Hybrid Zones: Two Instances of Repeated Hybridization in One Species Group (Genus Liolaemus). Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.624109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hybridization is an evolutionary process that can generate diverse outcomes, such as reinforcing species boundaries, generating new species, or facilitating the introgression of locally-adapted alleles into new genomic backgrounds. Liolaemus is a highly diverse clade of South American lizards with ~260 species and as many as ten new species are described each year. Previous Liolaemus studies have detected gene flow and introgression among species using phylogenetic network methods and/or through comparisons of nuclear and mitochondrial DNA patterns, yet no study has systematically studied hybrid zones between Liolaemus species. Here, we compared three hybrid zones between four species in the Liolaemus fitzingerii group of lizards in Central Argentina where two species, L. melanops and L. xanthoviridis, each hybridize with two other species (L. shehuen and L. fitzingerii). We sampled three transects that were each ~120 km in length and sequenced both mitochondrial and genome-wide SNP data for 267 individuals. In our analyses of nuclear DNA, we also compared bi-allelic SNPs to phased alleles (50 bp RAD loci). Population structure analyses confirmed that boundaries separating species are sharp, and all clines are <65 km wide. Cline center estimates were consistent between SNPs and phased alleles, but cline width estimates were significantly different with the SNPs producing wider estimates. The mitochondrial clines are narrower and shifted 4–20 km southward in comparison to the nuclear clines in all three hybrid zones, indicating that either each of the species has sex-biased dispersal (males northward or females southward), the population densities are unequal, or that the hybrid zones are moving north over time. These comparisons indicate that some patterns of hybridization are similar across hybrid zones (mtDNA clines all narrower and shifted to the south), whereas cline width is variable. Hybridization in the L. fitzingerii group is common and geographically localized; further studies are needed to investigate whether hybrid zones act as hard species boundaries or promoters of speciation through processes such as reinforcement. Nonetheless, this study provides insights into both biotic and abiotic mechanisms helping to maintain species boundaries within the speciose Liolaemus system.
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9
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Pereira RJ, Lima TG, Pierce-Ward NT, Chao L, Burton RS. Recovery from hybrid breakdown reveals a complex genetic architecture of mitonuclear incompatibilities. Mol Ecol 2021; 30:6403-6416. [PMID: 34003535 DOI: 10.1111/mec.15985] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/29/2021] [Accepted: 05/11/2021] [Indexed: 01/03/2023]
Abstract
Reproductive isolation is often achieved when genes that are neutral or beneficial in their genomic background become functionally incompatible in a foreign genomic background, causing inviability, sterility or other forms of low fitness in hybrids. Recent studies suggest that mitonuclear interactions are among the initial incompatibilities to evolve at early stages of population divergence across taxa. Yet, the genomic architecture of mitonuclear incompatibilities has rarely been elucidated. We employ an experimental evolution approach starting with low-fitness F2 interpopulation hybrids of the copepod Tigriopus californicus, in which frequencies of compatible and incompatible nuclear alleles change in response to an alternative mitochondrial background. After about nine generations, we observe a generalized increase in population size and in survivorship, suggesting efficiency of selection against maladaptive phenotypes. Whole genome sequencing of evolved populations showed some consistent allele frequency changes across three replicates of each reciprocal cross, but markedly different patterns between mitochondrial backgrounds. In only a few regions (~6.5% of the genome), the same parental allele was overrepresented irrespective of the mitochondrial background. About 33% of the genome showed allele frequency changes consistent with divergent selection, with the location of these genomic regions strongly differing between mitochondrial backgrounds. In 87% and 89% of these genomic regions, the dominant nuclear allele matched the associated mitochondrial background, consistent with mitonuclear co-adaptation. These results suggest that mitonuclear incompatibilities have a complex polygenic architecture that differs between populations, potentially generating genome-wide barriers to gene flow between closely related taxa.
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Affiliation(s)
- Ricardo J Pereira
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thiago G Lima
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - N Tessa Pierce-Ward
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Lin Chao
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Ronald S Burton
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
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10
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Premachandra HKA, la Cruz FLD, Takeuchi Y, Miller A, Fielder S, O'Connor W, Frère CH, Nguyen NH, Bar I, Knibb W. Genomic DNA variation confirmed Seriola lalandi comprises three different populations in the Pacific, but with recent divergence. Sci Rep 2017; 7:9386. [PMID: 28839140 PMCID: PMC5571200 DOI: 10.1038/s41598-017-07419-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 07/10/2017] [Indexed: 01/07/2023] Open
Abstract
Captive breeding programs and aquaculture production have commenced worldwide for the globally distributed yellowtail kingfish (Seriola lalandi), and captive bred fingerlings are being shipped from the Southern Hemisphere to be farmed in the Northern Hemisphere. It was recently proposed that Pacific S. lalandi comprise at least three distinct species that diverged more than 2 million years ago. Here, we tested the hypothesis of different “species” in the Pacific using novel genomic data (namely single nucleotide polymorphisms and diversity array technology markers), as well as mtDNA and DNA microsatellite variation. These new data support the hypothesis of population subdivision between the Northeast Pacific, Northwest Pacific and South Pacific, and genetic divergence indicates restriction to the gene flow between hemispheres. However, our estimates of maximum mtDNA and nuclear DNA divergences of 2.43% and 0.67%, respectively, were within the ranges more commonly observed for populations within species than species within genera. Accordingly our data support the more traditional view that S. lalandi in the Pacific comprises three distinct populations rather than the subdivisions into several species.
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Affiliation(s)
- H K A Premachandra
- Genecology Research Centre, Faculty of Science, Health, Education, and Engineering, University of the Sunshine Coast, Maroochydore, DC, QLD 4558, Australia
| | | | - Yutaka Takeuchi
- Division of Fisheries Resource Sciences, Faculty of Fisheries, Kagoshima University, Shimoarata 4-50-20, Kagoshima city, 890-0056, Japan
| | - Adam Miller
- Clean Seas Tuna Limited, 7 North Quay Boulevard, Port Lincoln, SA, 5606, Australia
| | - Stewart Fielder
- Department of Primary Industries, Port Stephens Fisheries Institute, Taylors Beach Road, Taylors Beach, NSW 2316, Australia
| | - Wayne O'Connor
- Department of Primary Industries, Port Stephens Fisheries Institute, Taylors Beach Road, Taylors Beach, NSW 2316, Australia
| | - Celine H Frère
- Genecology Research Centre, Faculty of Science, Health, Education, and Engineering, University of the Sunshine Coast, Maroochydore, DC, QLD 4558, Australia
| | - Nguyen Hong Nguyen
- Genecology Research Centre, Faculty of Science, Health, Education, and Engineering, University of the Sunshine Coast, Maroochydore, DC, QLD 4558, Australia
| | - Ido Bar
- Genecology Research Centre, Faculty of Science, Health, Education, and Engineering, University of the Sunshine Coast, Maroochydore, DC, QLD 4558, Australia
| | - Wayne Knibb
- Genecology Research Centre, Faculty of Science, Health, Education, and Engineering, University of the Sunshine Coast, Maroochydore, DC, QLD 4558, Australia.
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11
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Ryan SF, Fontaine MC, Scriber JM, Pfrender ME, O'Neil ST, Hellmann JJ. Patterns of divergence across the geographic and genomic landscape of a butterfly hybrid zone associated with a climatic gradient. Mol Ecol 2017; 26:4725-4742. [DOI: 10.1111/mec.14236] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Sean F. Ryan
- USDA ARS Gainesville FL USA
- Department of Biological Sciences University of Notre Dame South Bend IN USA
| | - Michael C. Fontaine
- Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen AG Groningen The Netherlands
| | - J. Mark Scriber
- Department of Entomology Michigan State University East Lansing MI USA
- McGuire Center for Lepidoptera and Diversity University of Florida Gainesville FL USA
| | - Michael E. Pfrender
- Department of Biological Sciences University of Notre Dame South Bend IN USA
- Environmental Change Initiative University of Notre Dame South Bend IN USA
| | - Shawn T. O'Neil
- Department of Biological Sciences University of Notre Dame South Bend IN USA
- Center for Genome Research and Biocomputing Oregon State University Corvallis OR USA
| | - Jessica J. Hellmann
- Department of Biological Sciences University of Notre Dame South Bend IN USA
- Institute on the Environment and Department of Ecology, Evolution and Behavior University of Minnesota St. Paul MN USA
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12
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Ribardière A, Daguin-Thiébaut C, Houbin C, Coudret J, Broudin C, Timsit O, Broquet T. Geographically distinct patterns of reproductive isolation and hybridization in two sympatric species of the Jaera albifrons complex (marine isopods). Ecol Evol 2017; 7:5352-5365. [PMID: 28770073 PMCID: PMC5528242 DOI: 10.1002/ece3.3106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/28/2017] [Accepted: 05/10/2017] [Indexed: 01/25/2023] Open
Abstract
Sympatric species that in some populations hybridize and in other populations remain reproductively isolated open interesting research possibilities for the study of hybridization and speciation. Here, we test for such a situation in two littoral isopods (Jaera albifrons and J. praehirsuta) that occur in mixed populations and where past morphological descriptions suggested that the two species are generally reproductively isolated except in rare populations where hybridization may be happening. Using field surveys and microsatellite genetic structure analyses in two regions from France (Normandy and Brittany), we confirmed that introgressive hybridization occurs in a subset of mixed J. albifrons/J. praehirsuta populations (region Normandy) where the two species are found in the same habitat (pebbles on the shore). Moreover, we found that introgression in these populations is differential, 21 of 23 microsatellite markers showing little genetic divergence between species (hierarchical analysis of molecular variance FCT = 0.017) while the remaining two loci were strongly differentiated (FCT = 0.428). By contrast, J. albifrons and J. praehirsuta in mixed populations from region Brittany occupied distinct habitats (pebbles and seaweeds, respectively) with little overlap and showed stronger genetic divergence (FCT = 0.132). In hybridizing populations, the majority of individuals show morphological traits that are characteristic of one or the other species. This raises the question of the forces that act to maintain this polymorphism, noting that hybridizing populations seem to be geographically isolated from potential source parental populations and show no detectable habitat divergence between species.
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Affiliation(s)
- Ambre Ribardière
- Centre National de la Recherche Scientifique Team Diversity and Connectivity of Coastal Marine Landscapes Roscoff France.,Sorbonne Universités UPMC Univ Paris 06 Roscoff France
| | - Claire Daguin-Thiébaut
- Centre National de la Recherche Scientifique Team Diversity and Connectivity of Coastal Marine Landscapes Roscoff France.,Sorbonne Universités UPMC Univ Paris 06 Roscoff France
| | - Céline Houbin
- Sorbonne Universités UPMC Univ Paris 06 Roscoff France.,Centre National de la Recherche Scientifique Roscoff France
| | - Jérôme Coudret
- Centre National de la Recherche Scientifique Team Diversity and Connectivity of Coastal Marine Landscapes Roscoff France.,Sorbonne Universités UPMC Univ Paris 06 Roscoff France
| | - Caroline Broudin
- Sorbonne Universités UPMC Univ Paris 06 Roscoff France.,Centre National de la Recherche Scientifique Roscoff France
| | - Olivier Timsit
- Groupe d'Etude des Milieux Estuariens et Littoraux de Normandie Centre Régional d'Etudes Côtières Luc-sur-Mer France
| | - Thomas Broquet
- Centre National de la Recherche Scientifique Team Diversity and Connectivity of Coastal Marine Landscapes Roscoff France.,Sorbonne Universités UPMC Univ Paris 06 Roscoff France
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13
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Sloan DB, Havird JC, Sharbrough J. The on-again, off-again relationship between mitochondrial genomes and species boundaries. Mol Ecol 2017; 26:2212-2236. [PMID: 27997046 PMCID: PMC6534505 DOI: 10.1111/mec.13959] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 11/16/2016] [Accepted: 11/18/2016] [Indexed: 12/12/2022]
Abstract
The study of reproductive isolation and species barriers frequently focuses on mitochondrial genomes and has produced two alternative and almost diametrically opposed narratives. On one hand, mtDNA may be at the forefront of speciation events, with co-evolved mitonuclear interactions responsible for some of the earliest genetic incompatibilities arising among isolated populations. On the other hand, there are numerous cases of introgression of mtDNA across species boundaries even when nuclear gene flow is restricted. We argue that these seemingly contradictory patterns can result from a single underlying cause. Specifically, the accumulation of deleterious mutations in mtDNA creates a problem with two alternative evolutionary solutions. In some cases, compensatory or epistatic changes in the nuclear genome may ameliorate the effects of mitochondrial mutations, thereby establishing coadapted mitonuclear genotypes within populations and forming the basis of reproductive incompatibilities between populations. Alternatively, populations with high mitochondrial mutation loads may be rescued by replacement with a more fit, foreign mitochondrial haplotype. Coupled with many nonadaptive mechanisms of introgression that can preferentially affect cytoplasmic genomes, this form of adaptive introgression may contribute to the widespread discordance between mitochondrial and nuclear genealogies. Here, we review recent advances related to mitochondrial introgression and mitonuclear incompatibilities, including the potential for cointrogression of mtDNA and interacting nuclear genes. We also address an emerging controversy over the classic assumption that selection on mitochondrial genomes is inefficient and discuss the mechanisms that lead lineages down alternative evolutionary paths in response to mitochondrial mutation accumulation.
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Affiliation(s)
- Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Justin C Havird
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Joel Sharbrough
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
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14
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Bateman AW, Anholt BR. Maintenance of polygenic sex determination in a fluctuating environment: an individual-based model. J Evol Biol 2017; 30:915-925. [DOI: 10.1111/jeb.13054] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/21/2016] [Accepted: 02/07/2017] [Indexed: 01/25/2023]
Affiliation(s)
- A. W. Bateman
- Department of Biological Sciences; University of Alberta; Edmonton AB Canada
- Department of Biology; University of Victoria; Victoria BC Canada
| | - B. R. Anholt
- Department of Biology; University of Victoria; Victoria BC Canada
- Bamfield Marine Sciences Centre; Bamfield BC Canada
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15
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Hwang AS, Pritchard VL, Edmands S. Recovery from hybrid breakdown in a marine invertebrate is faster, stronger and more repeatable under environmental stress. J Evol Biol 2016; 29:1793-803. [DOI: 10.1111/jeb.12913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 05/30/2016] [Indexed: 11/26/2022]
Affiliation(s)
- A. S. Hwang
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - V. L. Pritchard
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - S. Edmands
- Department of Biological Sciences University of Southern California Los Angeles CA USA
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16
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Haines ML, Melville J, Sumner J, Clemann N, Chapple DG, Stuart-Fox D. Geographic variation in hybridization and ecological differentiation between three syntopic, morphologically similar species of montane lizards. Mol Ecol 2016; 25:2887-903. [DOI: 10.1111/mec.13652] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 03/28/2016] [Accepted: 04/12/2016] [Indexed: 11/28/2022]
Affiliation(s)
- M. L. Haines
- Sciences Department; Museum Victoria; GPO Box 666 Melbourne Vic. 3001 Australia
- Biosciences; University of Melbourne; Parkville Vic. 3010 Australia
| | - J. Melville
- Sciences Department; Museum Victoria; GPO Box 666 Melbourne Vic. 3001 Australia
| | - J. Sumner
- Sciences Department; Museum Victoria; GPO Box 666 Melbourne Vic. 3001 Australia
| | - N. Clemann
- Sciences Department; Museum Victoria; GPO Box 666 Melbourne Vic. 3001 Australia
- Arthur Rylah Institute for Environmental Research; Department of Environment; Land, Water, and Planning; PO Box 137 Heidelberg Vic. 3084 Australia
| | - D. G. Chapple
- School of Biological Sciences; Monash University; Clayton Vic. 3800 Australia
| | - D. Stuart-Fox
- Biosciences; University of Melbourne; Parkville Vic. 3010 Australia
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17
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Hereford J. Variance and variability, uncovering an underappreciated component of reproductive isolation. J Evol Biol 2016; 29:1338-45. [PMID: 27038347 DOI: 10.1111/jeb.12874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 03/08/2016] [Accepted: 03/21/2016] [Indexed: 11/30/2022]
Abstract
Estimating the fitness of line crosses has been a key element in studies of inbreeding depression, hybridization, and speciation. Fitness values are typically compared using differences in the arithmetic mean of a fitness component between types of crosses. One aspect of fitness that is often overlooked is variance in offspring fitness over time. In the majority of studies, ignoring this aspect of fitness is unavoidable because it is impossible to estimate variance in offspring fitness over long time periods. Here, I describe a method of estimating variance in offspring fitness by substituting spatial variation for temporal variation and provide an empirical example. The method is based on Levene's test of homogeneity of variances. It is implemented by quantifying differences in residual variation among cross types. In a previous study, I performed crosses between populations of the annual plant Diodia teres and quantified hybrid fitness. In this study, another component of isolation and heterosis was revealed when considering variance in offspring fitness. When taking into account variance in offspring fitness using geometric mean fitness as the measure of performance, hybrids between populations from different habitats showed less heterosis than when calculating fitness based on arithmetic mean. This study demonstrates that variance in offspring fitness can be an important aspect of fitness that should be measured more frequently.
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Affiliation(s)
- J Hereford
- Evoluiton and Ecology, University of California, Davis, Davis, CA, USA
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18
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Todesco M, Pascual MA, Owens GL, Ostevik KL, Moyers BT, Hübner S, Heredia SM, Hahn MA, Caseys C, Bock DG, Rieseberg LH. Hybridization and extinction. Evol Appl 2016; 9:892-908. [PMID: 27468307 PMCID: PMC4947151 DOI: 10.1111/eva.12367] [Citation(s) in RCA: 339] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/28/2016] [Indexed: 01/29/2023] Open
Abstract
Hybridization may drive rare taxa to extinction through genetic swamping, where the rare form is replaced by hybrids, or by demographic swamping, where population growth rates are reduced due to the wasteful production of maladaptive hybrids. Conversely, hybridization may rescue the viability of small, inbred populations. Understanding the factors that contribute to destructive versus constructive outcomes of hybridization is key to managing conservation concerns. Here, we survey the literature for studies of hybridization and extinction to identify the ecological, evolutionary, and genetic factors that critically affect extinction risk through hybridization. We find that while extinction risk is highly situation dependent, genetic swamping is much more frequent than demographic swamping. In addition, human involvement is associated with increased risk and high reproductive isolation with reduced risk. Although climate change is predicted to increase the risk of hybridization‐induced extinction, we find little empirical support for this prediction. Similarly, theoretical and experimental studies imply that genetic rescue through hybridization may be equally or more probable than demographic swamping, but our literature survey failed to support this claim. We conclude that halting the introduction of hybridization‐prone exotics and restoring mature and diverse habitats that are resistant to hybrid establishment should be management priorities.
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Affiliation(s)
- Marco Todesco
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Mariana A Pascual
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Gregory L Owens
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Katherine L Ostevik
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Brook T Moyers
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada; Department of Bioagricultural Sciences and Pest Management Colorado State University Ft Collins CO USA
| | - Sariel Hübner
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Sylvia M Heredia
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Min A Hahn
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Celine Caseys
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Dan G Bock
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada; Department of Biology Indiana University Bloomington IN USA
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19
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Alexander HJ, Richardson JML, Edmands S, Anholt BR. Sex without sex chromosomes: genetic architecture of multiple loci independently segregating to determine sex ratios in the copepod Tigriopus californicus. J Evol Biol 2015; 28:2196-207. [DOI: 10.1111/jeb.12743] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 08/19/2015] [Accepted: 08/25/2015] [Indexed: 11/27/2022]
Affiliation(s)
- H. J. Alexander
- Bamfield Marine Sciences Centre; Bamfield BC Canada
- Department of Biology; University of Victoria; Victoria BC Canada
| | - J. M. L. Richardson
- Bamfield Marine Sciences Centre; Bamfield BC Canada
- Department of Biology; University of Victoria; Victoria BC Canada
| | - S. Edmands
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - B. R. Anholt
- Bamfield Marine Sciences Centre; Bamfield BC Canada
- Department of Biology; University of Victoria; Victoria BC Canada
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20
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Beck EA, Thompson AC, Sharbrough J, Brud E, Llopart A. Gene flow between Drosophila yakuba and Drosophila santomea in subunit V of cytochrome c oxidase: A potential case of cytonuclear cointrogression. Evolution 2015; 69:1973-86. [PMID: 26155926 PMCID: PMC5042076 DOI: 10.1111/evo.12718] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 06/13/2015] [Accepted: 06/16/2015] [Indexed: 12/11/2022]
Abstract
Introgression is the effective exchange of genetic information between species through natural hybridization. Previous genetic analyses of the Drosophila yakuba—D. santomea hybrid zone showed that the mitochondrial genome of D. yakuba had introgressed into D. santomea and completely replaced its native form. Since mitochondrial proteins work intimately with nuclear‐encoded proteins in the oxidative phosphorylation (OXPHOS) pathway, we hypothesized that some nuclear genes in OXPHOS cointrogressed along with the mitochondrial genome. We analyzed nucleotide variation in the 12 nuclear genes that form cytochrome c oxidase (COX) in 33 Drosophila lines. COX is an OXPHOS enzyme composed of both nuclear‐ and mitochondrial‐encoded proteins and shows evidence of cytonuclear coadaptation in some species. Using maximum‐likelihood methods, we detected significant gene flow from D. yakuba to D. santomea for the entire COX complex. Interestingly, the signal of introgression is concentrated in the three nuclear genes composing subunit V, which shows population migration rates significantly greater than the background level of introgression in these species. The detection of introgression in three proteins that work together, interact directly with the mitochondrial‐encoded core, and are critical for early COX assembly suggests this could be a case of cytonuclear cointrogression.
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Affiliation(s)
- Emily A Beck
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, Iowa, 52242
| | - Aaron C Thompson
- The Department of Biology, The University of Iowa, Iowa City, IA, 52242
| | - Joel Sharbrough
- The Department of Biology, The University of Iowa, Iowa City, IA, 52242
| | - Evgeny Brud
- The Department of Biology, The University of Iowa, Iowa City, IA, 52242
| | - Ana Llopart
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, Iowa, 52242. .,The Department of Biology, The University of Iowa, Iowa City, IA, 52242.
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21
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Stelkens RB, Schmid C, Seehausen O. Hybrid breakdown in cichlid fish. PLoS One 2015; 10:e0127207. [PMID: 25996870 PMCID: PMC4440740 DOI: 10.1371/journal.pone.0127207] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/13/2015] [Indexed: 12/22/2022] Open
Abstract
Studies from a wide diversity of taxa have shown a negative relationship between genetic compatibility and the divergence time of hybridizing genomes. Theory predicts the main breakdown of fitness to happen after the F1 hybrid generation, when heterosis subsides and recessive allelic (Dobzhansky-Muller) incompatibilities are increasingly unmasked. We measured the fitness of F2 hybrids of African haplochromine cichlid fish bred from species pairs spanning several thousand to several million years divergence time. F2 hybrids consistently showed the lowest viability compared to F1 hybrids and non-hybrid crosses (crosses within the grandparental species), in agreement with hybrid breakdown. Especially the short- and long-term survival (2 weeks to 6 months) of F2 hybrids was significantly reduced. Overall, F2 hybrids showed a fitness reduction of 21% compared to F1 hybrids, and a reduction of 43% compared to the grandparental, non-hybrid crosses. We further observed a decrease of F2 hybrid viability with the genetic distance between grandparental lineages, suggesting an important role for negative epistatic interactions in cichlid fish postzygotic isolation. The estimated time window for successful production of F2 hybrids resulting from our data is consistent with the estimated divergence time between the multiple ancestral lineages that presumably hybridized in three major adaptive radiations of African cichlids.
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Affiliation(s)
| | - Corinne Schmid
- Department of Aquatic Ecology and Macroevolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
| | - Ole Seehausen
- Department of Aquatic Ecology and Macroevolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
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22
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Schumer M, Cui R, Rosenthal GG, Andolfatto P. Reproductive isolation of hybrid populations driven by genetic incompatibilities. PLoS Genet 2015; 11:e1005041. [PMID: 25768654 PMCID: PMC4359097 DOI: 10.1371/journal.pgen.1005041] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 01/29/2015] [Indexed: 12/25/2022] Open
Abstract
Despite its role in homogenizing populations, hybridization has also been proposed as a means to generate new species. The conceptual basis for this idea is that hybridization can result in novel phenotypes through recombination between the parental genomes, allowing a hybrid population to occupy ecological niches unavailable to parental species. Here we present an alternative model of the evolution of reproductive isolation in hybrid populations that occurs as a simple consequence of selection against genetic incompatibilities. Unlike previous models of hybrid speciation, our model does not incorporate inbreeding, or assume that hybrids have an ecological or reproductive fitness advantage relative to parental populations. We show that reproductive isolation between hybrids and parental species can evolve frequently and rapidly under this model, even in the presence of substantial ongoing immigration from parental species and strong selection against hybrids. An interesting prediction of our model is that replicate hybrid populations formed from the same pair of parental species can evolve reproductive isolation from each other. This non-adaptive process can therefore generate patterns of species diversity and relatedness that resemble an adaptive radiation. Intriguingly, several known hybrid species exhibit patterns of reproductive isolation consistent with the predictions of our model.
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Affiliation(s)
- Molly Schumer
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Rongfeng Cui
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, Calnali, Hidalgo, Mexico
- Max Planck Institute for the Biology of Ageing, Cologne, Germany
| | - Gil G. Rosenthal
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, Calnali, Hidalgo, Mexico
| | - Peter Andolfatto
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
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23
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Wallace GT, Kim TL, Neufeld CJ. Interpopulational variation in the cold tolerance of a broadly distributed marine copepod. CONSERVATION PHYSIOLOGY 2014; 2:cou041. [PMID: 27293662 PMCID: PMC4732475 DOI: 10.1093/conphys/cou041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 08/14/2014] [Accepted: 08/19/2014] [Indexed: 06/06/2023]
Abstract
Latitudinal trends in cold tolerance have been observed in many terrestrial ectotherms, but few studies have investigated interpopulational variation in the cold physiology of marine invertebrates. Here, the intertidal copepod Tigriopus californicus was used as a model system to study how local adaptation influences the cold tolerance of a broadly distributed marine crustacean. Among five populations spanning 18° in latitude, the following three metrics were used to compare cold tolerance: the temperature of chill-coma onset, the chill-coma recovery time and post-freezing recovery. In comparison to copepods from warmer southern latitudes, animals from northern populations exhibited lower chill-coma onset temperatures, shorter chill-coma recovery times and faster post-freezing recovery rates. Importantly, all three metrics showed a consistent latitudinal trend, suggesting that any single metric could be used equivalently in future studies investigating latitudinal variation in cold tolerance. Our results agree with previous studies showing that populations within a single species can display strong local adaptation to spatially varying climatic conditions. Thus, accounting for local adaptation in bioclimate models will be useful for understanding how broadly distributed species like T. californicus will respond to anthropogenic climate change.
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Affiliation(s)
- Gemma T. Wallace
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Biology Department, Whitman College, Walla Walla, WA 99362, USA
| | - Tiffany L. Kim
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Department of Environmental Sciences, Northwestern University, Evanston, IL 60208, USA
| | - Christopher J. Neufeld
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Quest University Canada, Squamish, BC, Canada VB8 0N8
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24
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Trier CN, Hermansen JS, Sætre GP, Bailey RI. Evidence for mito-nuclear and sex-linked reproductive barriers between the hybrid Italian sparrow and its parent species. PLoS Genet 2014; 10:e1004075. [PMID: 24415954 PMCID: PMC3886922 DOI: 10.1371/journal.pgen.1004075] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 11/18/2013] [Indexed: 11/19/2022] Open
Abstract
Studies of reproductive isolation between homoploid hybrid species and their parent species have rarely been carried out. Here we investigate reproductive barriers between a recently recognized hybrid bird species, the Italian sparrow Passer italiae and its parent species, the house sparrow P. domesticus and Spanish sparrow P. hispaniolensis. Reproductive barriers can be difficult to study in hybrid species due to lack of geographical contact between taxa. However, the Italian sparrow lives parapatrically with the house sparrow and both sympatrically and parapatrically with the Spanish sparrow. Through whole-transcriptome sequencing of six individuals of each of the two parent species we identified a set of putatively parent species-diagnostic single nucleotide polymorphism (SNP) markers. After filtering for coverage, genotyping success (>97%) and multiple SNPs per gene, we retained 86 species-informative, genic, nuclear and mitochondrial SNP markers from 84 genes for analysis of 612 male individuals. We show that a disproportionately large number of sex-linked genes, as well as the mitochondria and nuclear genes with mitochondrial function, exhibit sharp clines at the boundaries between the hybrid and the parent species, suggesting a role for mito-nuclear and sex-linked incompatibilities in forming reproductive barriers. We suggest that genomic conflict via interactions between mitochondria and sex-linked genes with mitochondrial function (“mother's curse”) at one boundary and centromeric drive at the other may best explain our findings. Hybrid speciation in the Italian sparrow may therefore be influenced by mechanisms similar to those involved in non-hybrid speciation, but with the formation of two geographically separated species boundaries instead of one. Spanish sparrow alleles at some loci have spread north to form reproductive barriers with house sparrows, while house sparrow alleles at different loci, including some on the same chromosome, have spread in the opposite direction to form barriers against Spanish sparrows. Hybridization between two species has the potential to create a third, hybrid species. However this process, known as hybrid speciation, is thought to be unlikely because it requires reproductive barriers against both parent species to develop despite the barriers between parents being weak enough to allow for the formation of viable, fertile hybrids. The Italian sparrow, which occupies the entire Italian peninsula and some Mediterranean islands, is the product of past hybridization between house and Spanish sparrows and therefore represents one of the few documented cases of vertebrate hybrid speciation in nature. We show that reproductive barriers between Italian sparrows and their parent species exist and that genes on the sex (Z) chromosome and mitochondria are heavily involved. We suggest that speciation in this system may have been driven by dissociation of the sex (Z) chromosome into blocks of different parent species-specific genes, which have shifted alongside mitochondrial genes to form reproductive barriers where the hybrid now meets each of its parent species.
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Affiliation(s)
- Cassandra N. Trier
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, Norway
| | - Jo S. Hermansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, Norway
| | - Glenn-Peter Sætre
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, Norway
- * E-mail:
| | - Richard I. Bailey
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, Oslo, Norway
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25
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Foley BR, Rose CG, Rundle DE, Leong W, Edmands S. Postzygotic isolation involves strong mitochondrial and sex-specific effects in Tigriopus californicus, a species lacking heteromorphic sex chromosomes. Heredity (Edinb) 2013; 111:391-401. [PMID: 23860232 DOI: 10.1038/hdy.2013.61] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 05/08/2013] [Accepted: 05/13/2013] [Indexed: 11/09/2022] Open
Abstract
Detailed studies of the genetics of speciation have focused on a few model systems, particularly Drosophila. The copepod Tigriopus californicus offers an alternative that differs from standard animal models in that it lacks heteromorphic chromosomes (instead, sex determination is polygenic) and has reduced opportunities for sexual conflict, because females mate only once. Quantitative trait loci (QTL) mapping was conducted on reciprocal F2 hybrids between two strongly differentiated populations, using a saturated linkage map spanning all 12 autosomes and the mitochondrion. By comparing sexes, a possible sex ratio distorter was found but no sex chromosomes. Although studies of standard models often find an excess of hybrid male sterility factors, we found no QTL for sterility and multiple QTL for hybrid viability (indicated by non-Mendelian adult ratios) and other characters. Viability problems were found to be stronger in males, but the usual explanations for weaker hybrid males (sex chromosomes, sensitivity of spermatogenesis, sexual selection) cannot fully account for these male viability problems. Instead, higher metabolic rates may amplify deleterious effects in males. Although many studies of standard speciation models find the strongest genetic incompatibilities to be nuclear-nuclear (specifically X chromosome-autosome), we found the strongest deleterious interaction in this system was mito-nuclear. Consistent with the snowball theory of incompatibility accumulation, we found that trigenic interactions in this highly divergent cross were substantially more frequent (>6×) than digenic interactions. This alternative system thus allows important comparisons to studies of the genetics of reproductive isolation in more standard model systems.
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Affiliation(s)
- B R Foley
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
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26
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Pritchard VL, Knutson VL, Lee M, Zieba J, Edmands S. Fitness and morphological outcomes of many generations of hybridization in the copepod Tigriopus californicus. J Evol Biol 2012; 26:416-33. [DOI: 10.1111/jeb.12060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 10/23/2012] [Accepted: 10/24/2012] [Indexed: 12/27/2022]
Affiliation(s)
- V. L. Pritchard
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - V. L. Knutson
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - M. Lee
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - J. Zieba
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - S. Edmands
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
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