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] [What about the content of this article? (0)] [Affiliation(s)] [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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Groh JS, Coop G. The temporal and genomic scale of selection following hybridization. Proc Natl Acad Sci U S A 2024; 121:e2309168121. [PMID: 38489387 PMCID: PMC10962946 DOI: 10.1073/pnas.2309168121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 01/30/2024] [Indexed: 03/17/2024] Open
Abstract
Genomic evidence supports an important role for selection in shaping patterns of introgression along the genome, but frameworks for understanding the evolutionary dynamics within hybrid populations that underlie these patterns have been lacking. Due to the clock-like effect of recombination in hybrids breaking up parental haplotypes, drift and selection produce predictable patterns of ancestry variation at varying spatial genomic scales through time. Here, we develop methods based on the Discrete Wavelet Transform to study the genomic scale of local ancestry variation and its association with recombination rates and show that these methods capture temporal dynamics of drift and genome-wide selection after hybridization. We apply these methods to published datasets from hybrid populations of swordtail fish (Xiphophorus) and baboons (Papio) and to inferred Neanderthal introgression in modern humans. Across systems, upward of 20% of variation in local ancestry at the broadest genomic scales can be attributed to systematic selection against introgressed alleles, consistent with strong selection acting on early-generation hybrids. Signatures of selection at fine genomic scales suggest selection over longer time scales; however, we suggest that our ability to confidently infer selection at fine scales is likely limited by inherent biases in current methods for estimating local ancestry from contiguous segments of genomic similarity. Wavelet approaches will become widely applicable as genomic data from systems with introgression become increasingly available and can help shed light on generalities of the genomic consequences of interspecific hybridization.
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Affiliation(s)
- Jeffrey S. Groh
- Department of Evolution and Ecology and Center for Population Biology, University of California, Davis, CA95616
| | - Graham Coop
- Department of Evolution and Ecology and Center for Population Biology, University of California, Davis, CA95616
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3
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Berdan EL, Aubier TG, Cozzolino S, Faria R, Feder JL, Giménez MD, Joron M, Searle JB, Mérot C. Structural Variants and Speciation: Multiple Processes at Play. Cold Spring Harb Perspect Biol 2024; 16:a041446. [PMID: 38052499 PMCID: PMC10910405 DOI: 10.1101/cshperspect.a041446] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Research on the genomic architecture of speciation has increasingly revealed the importance of structural variants (SVs) that affect the presence, abundance, position, and/or direction of a nucleotide sequence. SVs include large chromosomal rearrangements such as fusion/fissions and inversions and translocations, as well as smaller variants such as duplications, insertions, and deletions (CNVs). Although we have ample evidence that SVs play a key role in speciation, the underlying mechanisms differ depending on the type and length of the SV, as well as the ecological, demographic, and historical context. We review predictions and empirical evidence for classic processes such as underdominance due to meiotic aberrations and the coupling effect of recombination suppression before exploring how recent sequencing methodologies illuminate the prevalence and diversity of SVs. We discuss specific properties of SVs and their impact throughout the genome, highlighting that multiple processes are at play, and possibly interacting, in the relationship between SVs and speciation.
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Affiliation(s)
- Emma L Berdan
- Department of Marine Sciences, Gothenburg University, Gothenburg 40530, Sweden
- Bioinformatics Core, Department of Biostatistics, Harvard T.H. Chan School of Public Health, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Thomas G Aubier
- Laboratoire Évolution & Diversité Biologique, Université Paul Sabatier Toulouse III, UMR 5174, CNRS/IRD, 31077 Toulouse, France
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Salvatore Cozzolino
- Department of Biology, University of Naples Federico II, Complesso Universitario di Monte S. Angelo, 80126 Napoli, Italia
| | - Rui Faria
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, 4485-661 Vairão, Portugal
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Mabel D Giménez
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Genética Humana de Misiones (IGeHM), Parque de la Salud de la Provincia de Misiones "Dr. Ramón Madariaga," N3300KAZ Posadas, Misiones, Argentina
- Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, N3300LQH Posadas, Misiones, Argentina
| | - Mathieu Joron
- Centre d'Ecologie Fonctionnelle et Evolutive, Université de Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Jeremy B Searle
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA
| | - Claire Mérot
- CNRS, UMR 6553 Ecobio, OSUR, Université de Rennes, 35000 Rennes, France
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4
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Wang Z, Luo W, Ping J, Xia Y, Ran J, Zeng X. Large X-effects are absent in torrent frogs with nascent sex chromosomes. Mol Ecol 2023; 32:5338-5349. [PMID: 37602937 DOI: 10.1111/mec.17113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/23/2023] [Accepted: 08/09/2023] [Indexed: 08/22/2023]
Abstract
Sex chromosomes are popularized as a special role in driving speciation. However, the empirical evidence from natural population processes has been limited to organisms with degenerated sex chromosomes, where hemizygosity is mainly considered to act as the driver of reproductive isolation. Here, we examined several hybrid zones of torrent frog Amolops mantzorum species complex, using an approach by mapping species-diagnostic loci onto the reference genome to compare sex-linked versus autosomal patterns of introgression. We find little support in sex-linked incompatibilities for large X-effects for these populations in hybrid zones with homomorphic sex chromosomes, due to the absence of the hemizygous effects. As expected, the large X-effects were not found in those with heteromorphic but newly evolved sex chromosomes, owing to the absence of strong genetic differences between X and Y chromosomes. The available data so far on amphibians suggest little role for sex-linked genes in speciation. The large X-effects in those with nascent sex chromosomes may not be as ubiquitous as presumed across the animal kingdom.
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Affiliation(s)
- Ziwen Wang
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wei Luo
- Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University, Mianyang, China
| | - Jun Ping
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yun Xia
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Jianghong Ran
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Xiaomao Zeng
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
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5
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Barnbrook M, Durán‐Castillo M, Critchley J, Wilson Y, Twyford A, Hudson A. Recent parallel speciation in Antirrhinum involved complex haplotypes and multiple adaptive characters. Mol Ecol 2023; 32:5305-5322. [PMID: 37602497 PMCID: PMC10947308 DOI: 10.1111/mec.17101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 08/22/2023]
Abstract
A role of ecological adaptation in speciation can be obscured by stochastic processes and differences that species accumulate after genetic isolation. One way to identify adaptive characters and their underlying genes is to study cases of speciation involving parallel adaptations. Recently resolved phylogenies reveal that alpine morphology has evolved in parallel in the genus Antirrhinum (snapdragons): first in an early split of an alpine from a lowland lineage and, more recently, from within the lowland lineage to produce closely related sympatric species with contrasting alpine and lowland forms. Here, we find that two of these later diverged sympatric species are differentiated by only around 2% of nuclear loci. Though showing evidence of recent gene flow, the species remain distinct for a suite of morphological characters typical of earlier-diverged alpine or lowland lineages and their morphologies correlate with features of the local landscape, as expected of ecological adaptations. Morphological differences between the two species involve multiple, unlinked genes so that parental character combinations are readily broken up by recombination in hybrids. We detect little evidence for post-pollination barriers to gene flow or recombination, suggesting that genetic isolation related to ecological adaptation is important in maintaining character combinations and might have contributed to parallel speciation. We also find evidence that genes involved in the earlier alpine-lowland split were reused in parallel evolution of alpine species, consistent with introgressive hybridisation, and speculate that many non-ecological barriers to gene flow might have been purged during the process.
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Affiliation(s)
| | | | - Jo Critchley
- University of Edinburgh School of Biological SciencesEdinburghUK
| | - Yvette Wilson
- University of Edinburgh School of Biological SciencesEdinburghUK
| | - Alex Twyford
- University of Edinburgh School of Biological SciencesEdinburghUK
- Royal Botanic Garden EdinburghEdinburghUK
| | - Andrew Hudson
- University of Edinburgh School of Biological SciencesEdinburghUK
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6
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Abstract
Genomic evidence supports an important role for selection in shaping patterns of introgression along the genome, but frameworks for understanding the dynamics underlying these patterns within hybrid populations have been lacking. Here, we develop methods based on the Wavelet Transform to understand the spatial genomic scale of local ancestry variation and its association with recombination rates. We present theory and use simulations to show how wavelet-based decompositions of ancestry variance along the genome and the correlation between ancestry and recombination reflect the joint effects of recombination, genetic drift, and genome-wide selection against introgressed alleles. Due to the clock-like effect of recombination in hybrids breaking up parental haplotypes, drift and selection produce predictable patterns of local ancestry variation at varying spatial genomic scales through time. Using wavelet approaches to identify the genomic scale of variance in ancestry and its correlates, we show that these methods can detect temporally localized effects of drift and selection. We apply these methods to previously published datasets from hybrid populations of swordtail fish (Xiphophorus) and baboons (Papio), and to inferred Neanderthal introgression in modern humans. Across systems, we find that upwards of 20% of the variation in local ancestry at the broadest genomic scales can be attributed to systematic selection against introgressed alleles, consistent with strong selection acting on early-generation hybrids. We also see signals of selection at fine genomic scales and much longer time scales. However, we show that our ability to confidently infer selection at fine scales is likely limited by inherent biases in current methods for estimating local ancestry from genomic similarity. Wavelet approaches will become widely applicable as genomic data from systems with introgression become increasingly available, and can help shed light on generalities of the genomic consequences of interspecific hybridization.
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Affiliation(s)
- Jeffrey Groh
- Department of Evolution and Ecology, and Center for Population Biology, University of California, Davis, CA 95616
| | - Graham Coop
- Department of Evolution and Ecology, and Center for Population Biology, University of California, Davis, CA 95616
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7
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van Riemsdijk I, Arntzen JW, Bucciarelli GM, McCartney-Melstad E, Rafajlović M, Scott PA, Toffelmier E, Shaffer HB, Wielstra B. Two transects reveal remarkable variation in gene flow on opposite ends of a European toad hybrid zone. Heredity (Edinb) 2023:10.1038/s41437-023-00617-6. [PMID: 37106116 DOI: 10.1038/s41437-023-00617-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 03/27/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Speciation entails a reduction in gene flow between lineages. The rates at which genomic regions become isolated varies across space and time. Barrier markers are linked to putative genes involved in (processes of) reproductive isolation, and, when observed over two transects, indicate species-wide processes. In contrast, transect-specific putative barrier markers suggest local processes. We studied two widely separated transects along the 900 km hybrid zone between Bufo bufo and B. spinosus, in northern and southern France, for ~1200 RADseq markers. We used genomic and geographic cline analyses to identify barrier markers based on their restricted introgression, and found that some markers are transect-specific, while others are shared between transects. Twenty-six barrier markers were shared across both transects, of which some are clustered in the same chromosomal region, suggesting that their associated genes are involved in reduced gene flow across the entire hybrid zone. Transect-specific barrier markers were twice as numerous in the southern than in the northern transect, suggesting that the overall barrier effect is weaker in northern France. We hypothesize that this is consistent with a longer period of secondary contact in southern France. The smaller number of introgressed genes in the northern transect shows considerably more gene flow towards the southern (B. spinosus) than the northern species (B. bufo). We hypothesize that hybrid zone movement in northern France and hybrid zone stability in southern France explain this pattern. The Bufo hybrid zone provides an excellent opportunity to separate a general barrier effect from localized gene flow-reducing conditions.
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Affiliation(s)
- I van Riemsdijk
- Naturalis Biodiversity Center, Leiden, the Netherlands.
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands.
- Institute for Evolution and Ecology, Plant Evolutionary Ecology, Tübingen University, Tübingen, Germany.
| | - J W Arntzen
- Naturalis Biodiversity Center, Leiden, the Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
| | - G M Bucciarelli
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
- Institute of the Environment, UC Davis, Davis, CA, USA
- Department of Wildlife, Fish, and Conservation Biology, UC Davis, Davis, CA, USA
| | - E McCartney-Melstad
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - M Rafajlović
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden
| | - P A Scott
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- Natural Sciences Collegium, Eckerd College, 4200 54 Ave S, St Petersburg, FL, 33711, USA
| | - E Toffelmier
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - H B Shaffer
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - B Wielstra
- Naturalis Biodiversity Center, Leiden, the Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
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8
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Schneemann H, Munzur AD, Thompson KA, Welch JJ. The diverse effects of phenotypic dominance on hybrid fitness. Evolution 2022; 76:2846-2863. [PMID: 36221216 PMCID: PMC10092378 DOI: 10.1111/evo.14645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/14/2022] [Indexed: 01/22/2023]
Abstract
When divergent populations interbreed, their alleles are brought together in hybrids. In the initial F1 cross, most divergent loci are heterozygous. Therefore, F1 fitness can be influenced by dominance effects that could not have been selected to function well together. We present a systematic study of these F1 dominance effects by introducing variable phenotypic dominance into Fisher's geometric model. We show that dominance often reduces hybrid fitness, which can generate optimal outbreeding followed by a steady decline in F1 fitness, as is often observed. We also show that "lucky" beneficial effects sometimes arise by chance, which might be important when hybrids can access novel environments. We then show that dominance can lead to violations of Haldane's Rule (reduced fitness of the heterogametic F1) but strengthens Darwin's Corollary (F1 fitness differences between cross directions). Taken together, results show that the effects of dominance on hybrid fitness can be surprisingly difficult to isolate, because they often resemble the effects of uniparental inheritance or expression. Nevertheless, we identify a pattern of environment-dependent heterosis that only dominance can explain, and for which there is some suggestive evidence. Our results also show how existing data set upper bounds on the size of dominance effects. These bounds could explain why additive models often provide good predictions for later-generation recombinant hybrids, even when dominance qualitatively changes outcomes for the F1.
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Affiliation(s)
- Hilde Schneemann
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, UK
| | - Aslı D Munzur
- Department of Zoology & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Ken A Thompson
- Department of Zoology & Biodiversity Research Centre, University of British Columbia, Vancouver, Canada.,Current address: Department of Biology, Stanford University & Department of Plant Biology, Carnegie Institution for Science, Stanford, USA
| | - John J Welch
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, UK
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9
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Foe VE. Does the Pachytene Checkpoint, a Feature of Meiosis, Filter Out Mistakes in Double-Strand DNA Break Repair and as a side-Effect Strongly Promote Adaptive Speciation? Integr Org Biol 2022; 4:obac008. [PMID: 36827645 PMCID: PMC8998493 DOI: 10.1093/iob/obac008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This essay aims to explain two biological puzzles: why eukaryotic transcription units are composed of short segments of coding DNA interspersed with long stretches of non-coding (intron) DNA, and the near ubiquity of sexual reproduction. As is well known, alternative splicing of its coding sequences enables one transcription unit to produce multiple variants of each encoded protein. Additionally, padding transcription units with non-coding DNA (often many thousands of base pairs long) provides a readily evolvable way to set how soon in a cell cycle the various mRNAs will begin being expressed and the total amount of mRNA that each transcription unit can make during a cell cycle. This regulation complements control via the transcriptional promoter and facilitates the creation of complex eukaryotic cell types, tissues, and organisms. However, it also makes eukaryotes exceedingly vulnerable to double-strand DNA breaks, which end-joining break repair pathways can repair incorrectly. Transcription units cover such a large fraction of the genome that any mis-repair producing a reorganized chromosome has a high probability of destroying a gene. During meiosis, the synaptonemal complex aligns homologous chromosome pairs and the pachytene checkpoint detects, selectively arrests, and in many organisms actively destroys gamete-producing cells with chromosomes that cannot adequately synapse; this creates a filter favoring transmission to the next generation of chromosomes that retain the parental organization, while selectively culling those with interrupted transcription units. This same meiotic checkpoint, reacting to accidental chromosomal reorganizations inflicted by error-prone break repair, can, as a side effect, provide a mechanism for the formation of new species in sympatry. It has been a long-standing puzzle how something as seemingly maladaptive as hybrid sterility between such new species can arise. I suggest that this paradox is resolved by understanding the adaptive importance of the pachytene checkpoint, as outlined above.
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10
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MacPherson A, Wang S, Yamaguchi R, Rieseberg L, Otto S. Parental Population Range Expansion Before Secondary Contact Promotes Heterosis. Am Nat 2022; 200:E1-E15. [DOI: 10.1086/719656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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11
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Abstract
Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles—including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
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Affiliation(s)
- Sarah E Banker
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - François Bonhomme
- Institut des Sciences de l'Evolution, Université de Montpellier, Montpellier, France
| | - Michael W Nachman
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, 94720, USA
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12
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Wong ELY, Hiscock SJ, Filatov DA. The Role of Interspecific Hybridisation in Adaptation and Speciation: Insights From Studies in Senecio. Front Plant Sci 2022; 13:907363. [PMID: 35812981 PMCID: PMC9260247 DOI: 10.3389/fpls.2022.907363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 06/03/2022] [Indexed: 05/08/2023]
Abstract
Hybridisation is well documented in many species, especially plants. Although hybrid populations might be short-lived and do not evolve into new lineages, hybridisaiton could lead to evolutionary novelty, promoting adaptation and speciation. The genus Senecio (Asteraceae) has been actively used to unravel the role of hybridisation in adaptation and speciation. In this article, we first briefly describe the process of hybridisation and the state of hybridisation research over the years. We then discuss various roles of hybridisation in plant adaptation and speciation illustrated with examples from different Senecio species, but also mention other groups of organisms whenever necessary. In particular, we focus on the genomic and transcriptomic consequences of hybridisation, as well as the ecological and physiological aspects from the hybrids' point of view. Overall, this article aims to showcase the roles of hybridisation in speciation and adaptation, and the research potential of Senecio, which is part of the ecologically and economically important family, Asteraceae.
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Affiliation(s)
- Edgar L. Y. Wong
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- *Correspondence: Edgar L. Y. Wong,
| | - Simon J. Hiscock
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- Oxford Botanic Garden and Arboretum, Oxford, United Kingdom
| | - Dmitry A. Filatov
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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13
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O'Donnell ST, Fitz-Gibbon ST, Sork VL. Ancient Introgression Between Distantly Related White Oaks (Quercus sect. Quercus) Shows Evidence of Climate-Associated Asymmetric Gene Exchange. J Hered 2021; 112:663-670. [PMID: 34508641 DOI: 10.1093/jhered/esab053] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 09/10/2021] [Indexed: 12/14/2022] Open
Abstract
Ancient introgression can be an important source of genetic variation that shapes the evolution and diversification of many taxa. Here, we estimate the timing, direction, and extent of gene flow between two distantly related oak species in the same section (Quercus sect. Quercus). We estimated these demographic events using genotyping by sequencing data, which generated 25 702 single nucleotide polymorphisms for 24 individuals of California scrub oak (Quercus berberidifolia) and 23 individuals of Engelmann oak (Quercus engelmannii). We tested several scenarios involving gene flow between these species using the diffusion approximation-based population genetic inference framework and model-testing approach of the Python package DaDi. We found that the most likely demographic scenario includes a bottleneck in Q. engelmannii that coincides with asymmetric gene flow from Q. berberidifolia into Q. engelmannii. Given that the timing of this gene flow coincides with the advent of a Mediterranean-type climate in the California Floristic Province, we propose that changing precipitation patterns and seasonality may have favored the introgression of climate-associated genes from the endemic into the non-endemic California oak.
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Affiliation(s)
- Scott T O'Donnell
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Sorel T Fitz-Gibbon
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Victoria L Sork
- Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
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14
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Zhao X, Fu X, Yin C, Lu F. Wheat speciation and adaptation: perspectives from reticulate evolution. aBIOTECH 2021; 2:386-402. [PMID: 36311810 PMCID: PMC9590565 DOI: 10.1007/s42994-021-00047-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022]
Abstract
Reticulate evolution through the interchanging of genetic components across organisms can impact significantly on the fitness and adaptation of species. Bread wheat (Triticum aestivum subsp. aestivum) is one of the most important crops in the world. Allopolyploid speciation, frequent hybridization, extensive introgression, and occasional horizontal gene transfer (HGT) have been shaping a typical paradigm of reticulate evolution in bread wheat and its wild relatives, which is likely to have a substantial influence on phenotypic traits and environmental adaptability of bread wheat. In this review, we outlined the evolutionary history of bread wheat and its wild relatives with a highlight on the interspecific hybridization events, demonstrating the reticulate relationship between species/subspecies in the genera Triticum and Aegilops. Furthermore, we discussed the genetic mechanisms and evolutionary significance underlying the introgression of bread wheat and its wild relatives. An in-depth understanding of the evolutionary process of Triticum species should be beneficial to future genetic study and breeding of bread wheat.
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Affiliation(s)
- Xuebo Zhao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiangdong Fu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Changbin Yin
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Fei Lu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- CAS-JIC Centre of Excellence for Plant and Microbial Science (CEPAMS), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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15
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Malinovskaya LP, Tishakova KV, Bikchurina TI, Slobodchikova AY, Torgunakov NY, Torgasheva AA, Tsepilov YA, Volkova NA, Borodin PM. Negative heterosis for meiotic recombination rate in spermatocytes of the domestic chicken Gallus gallus. Vavilovskii Zhurnal Genet Selektsii 2021; 25:661-668. [PMID: 34782886 PMCID: PMC8558918 DOI: 10.18699/vj21.075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/24/2022] Open
Abstract
Benef its and costs of meiotic recombination are a matter of discussion. Because recombination breaks
allele combinations already tested by natural selection and generates new ones of unpredictable f itness, a high
recombination rate is generally benef icial for the populations living in a f luctuating or a rapidly changing environment
and costly in a stable environment. Besides genetic benef its and costs, there are cytological effects of recombination,
both positive and negative. Recombination is necessary for chromosome synapsis and segregation. However,
it involves a massive generation of double-strand DNA breaks, erroneous repair of which may lead to germ
cell death or various mutations and chromosome rearrangements. Thus, the benef its of recombination (generation
of new allele combinations) would prevail over its costs (occurrence of deleterious mutations) as long as the population
remains suff iciently heterogeneous. Using immunolocalization of MLH1, a mismatch repair protein, at the
synaptonemal complexes, we examined the number and distribution of recombination nodules in spermatocytes
of two chicken breeds with high (Pervomai) and low (Russian Crested) recombination rates and their F1 hybrids and
backcrosses. We detected negative heterosis for recombination rate in the F1 hybrids. Backcrosses to the Pervomai
breed were rather homogenous and showed an intermediate recombination rate. The differences in overall recombination
rate between the breeds, hybrids and backcrosses were mainly determined by the differences in the crossing
over number in the seven largest macrochromosomes. The decrease in recombination rate in F1 is probably
determined by diff iculties in homology matching between the DNA sequences of genetically divergent breeds. The
suppression of recombination in the hybrids may impede gene f low between parapatric populations and therefore
accelerate their genetic divergence.
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Affiliation(s)
- L P Malinovskaya
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | | | - T I Bikchurina
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A Yu Slobodchikova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - N Yu Torgunakov
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A A Torgasheva
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Y A Tsepilov
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - N A Volkova
- L.K. Ernst Federal Research Center for Animal Husbandry, Dubrovitsy, Moscow region, Russia
| | - P M Borodin
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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16
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Metzler D, Knief U, Peñalba JV, Wolf JBW. Assortative mating and epistatic mating-trait architecture induce complex movement of the crow hybrid zone. Evolution 2021; 75:3154-3174. [PMID: 34694633 DOI: 10.1111/evo.14386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/06/2021] [Indexed: 12/20/2022]
Abstract
Hybrid zones provide a window into the evolutionary processes governing species divergence. Yet, the contribution of mate choice to the temporal and spatial stability of hybrid zones remains poorly explored. Here, we investigate the effects of assortative mating on hybrid-zone dynamics by means of a mathematical model parameterized with phenotype and genotype data from the hybrid zone between all-black carrion and gray-coated hooded crows. In the best-fit model, narrow clines of the two mating-trait loci were maintained by a moderate degree of assortative mating inducing pre- and postzygotic isolation via positive frequency-dependent selection. Epistasis between the two loci induced hybrid-zone movement in favor of alleles conveying dark plumage followed by a shift in the opposite direction favoring gray-coated phenotypes ∼ 1 200 generations after secondary contact. Unlinked neutral loci diffused near-unimpeded across the zone. These results were generally robust to the choice of matching rule (self-referencing or parental imprinting) and effects of genetic drift. Overall, this study illustrates under which conditions assortative mating can maintain steep clines in mating-trait loci without generalizing to genome-wide reproductive isolation. It further emphasizes the importance of the genetic mating-trait architecture for spatio-temporal hybrid-zone dynamics.
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Affiliation(s)
- Dirk Metzler
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Ulrich Knief
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Joshua V Peñalba
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
| | - Jochen B W Wolf
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, Munich, 80539, Germany
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17
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Wold J, Koepfli KP, Galla SJ, Eccles D, Hogg CJ, Le Lec MF, Guhlin J, Santure AW, Steeves TE. Expanding the conservation genomics toolbox: Incorporating structural variants to enhance genomic studies for species of conservation concern. Mol Ecol 2021; 30:5949-5965. [PMID: 34424587 PMCID: PMC9290615 DOI: 10.1111/mec.16141] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 07/28/2021] [Accepted: 08/18/2021] [Indexed: 12/28/2022]
Abstract
Structural variants (SVs) are large rearrangements (>50 bp) within the genome that impact gene function and the content and structure of chromosomes. As a result, SVs are a significant source of functional genomic variation, that is, variation at genomic regions underpinning phenotype differences, that can have large effects on individual and population fitness. While there are increasing opportunities to investigate functional genomic variation in threatened species via single nucleotide polymorphism (SNP) data sets, SVs remain understudied despite their potential influence on fitness traits of conservation interest. In this future-focused Opinion, we contend that characterizing SVs offers the conservation genomics community an exciting opportunity to complement SNP-based approaches to enhance species recovery. We also leverage the existing literature-predominantly in human health, agriculture and ecoevolutionary biology-to identify approaches for readily characterizing SVs and consider how integrating these into the conservation genomics toolbox may transform the way we manage some of the world's most threatened species.
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Affiliation(s)
- Jana Wold
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Klaus-Peter Koepfli
- Smithsonian-Mason School of Conservation, Front Royal, Virginia, USA.,Centre for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, District of Columbia, USA.,Computer Technologies Laboratory, ITMO University, Saint Petersburg, Russia
| | - Stephanie J Galla
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.,Department of Biological Sciences, Boise State University, Boise, Idaho, USA
| | - David Eccles
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Carolyn J Hogg
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Marissa F Le Lec
- Department of Biochemistry, University of Otago, Dunedin, Otago, New Zealand
| | - Joseph Guhlin
- Department of Biochemistry, University of Otago, Dunedin, Otago, New Zealand.,Genomics Aotearoa, Dunedin, Otago, New Zealand
| | - Anna W Santure
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Tammy E Steeves
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
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18
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Zhang L, Reifová R, Halenková Z, Gompert Z. How Important Are Structural Variants for Speciation? Genes (Basel) 2021; 12:1084. [PMID: 34356100 DOI: 10.3390/genes12071084] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/04/2021] [Accepted: 07/14/2021] [Indexed: 12/11/2022] Open
Abstract
Understanding the genetic basis of reproductive isolation is a central issue in the study of speciation. Structural variants (SVs); that is, structural changes in DNA, including inversions, translocations, insertions, deletions, and duplications, are common in a broad range of organisms and have been hypothesized to play a central role in speciation. Recent advances in molecular and statistical methods have identified structural variants, especially inversions, underlying ecologically important traits; thus, suggesting these mutations contribute to adaptation. However, the contribution of structural variants to reproductive isolation between species—and the underlying mechanism by which structural variants most often contribute to speciation—remain unclear. Here, we review (i) different mechanisms by which structural variants can generate or maintain reproductive isolation; (ii) patterns expected with these different mechanisms; and (iii) relevant empirical examples of each. We also summarize the available sequencing and bioinformatic methods to detect structural variants. Lastly, we suggest empirical approaches and new research directions to help obtain a more complete assessment of the role of structural variants in speciation.
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19
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Vasiliev D, Greenwood S. The role of climate change in pollinator decline across the Northern Hemisphere is underestimated. Sci Total Environ 2021; 775:145788. [PMID: 33618305 DOI: 10.1016/j.scitotenv.2021.145788] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/02/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
Pollinator biodiversity loss occurs at unprecedented rates globally, with particularly sharp declines documented in the North Temperate Zone. There is currently no consensus on the main drivers of the decline. Although climate change is expected to drive biodiversity loss in the future, current warming is often suggested to have positive impacts on pollinator assemblages in higher latitudes. Consequently, pollinator conservation initiatives in Europe and the USA tend to lack climate adaptation initiatives, an omission of which may be risky if climate change has significant negative impacts on pollinators. To gain an understanding of the impacts of climate change on pollinator biodiversity in the Northern Hemisphere, we conducted a literature review on genetic, species and community level diversity. Our findings suggest that global heating most likely causes homogenization of pollinator assemblages at all levels of pollinator biodiversity, making them less resilient to future stochasticity. Aspects of biodiversity that are rarely measured (e.g. genetic diversity, β-diversity, species evenness) tend to be most affected, while some dimensions of climate change, such as fluctuations in winter weather conditions, changes in the length of the vegetational season and increased frequency of extreme weather events, that seldom receive attention in empirical studies, tend to be particularly detrimental to pollinators. Negative effects of global heating on pollinator biodiversity are most likely exacerbated by homogenous and fragmented landscapes, widespread across Europe and the US, which limit opportunities for range-shifts and reduce micro-climatic buffering. This suggests the need for conservation initiatives to focus on increasing landscape connectivity and heterogeneity at multiple spatial scales.
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Affiliation(s)
- Denis Vasiliev
- Biodiversity, Wildlife and Ecosystem Health MSc, Biomedical Sciences, The University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, United Kingdom of Great Britain and Northern Ireland.
| | - Sarah Greenwood
- Biodiversity, Wildlife and Ecosystem Health MSc, Biomedical Sciences, The University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, United Kingdom of Great Britain and Northern Ireland
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20
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Abstract
Natural hybrid zones offer a powerful framework for understanding the genetic basis of speciation in progress because ongoing hybridization continually creates unfavorable gene combinations. Evidence indicates that postzygotic reproductive isolation is often caused by epistatic interactions between mutations in different genes that evolved independently of one another (hybrid incompatibilities). We examined the potential to detect epistatic selection against incompatibilities from genome sequence data using the site frequency spectrum (SFS) of polymorphisms by conducting individual-based simulations in SLiM. We found that the genome-wide SFS in hybrid populations assumes a diagnostic shape, with the continual input of fixed differences between source populations via migration inducing a mass at intermediate allele frequency. Epistatic selection locally distorts the SFS as non-incompatibility alleles rise in frequency in a manner analogous to a selective sweep. Building on these results, we present a statistical method to identify genomic regions containing incompatibility loci that locates departures in the local SFS compared with the genome-wide SFS. Cross-validation studies demonstrate that our method detects recessive and codominant incompatibilities across a range of scenarios varying in the strength of epistatic selection, migration rate, and hybrid zone age. Our approach takes advantage of whole genome sequence data, does not require knowledge of demographic history, and can be applied to any pair of nascent species that forms a hybrid zone.
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Affiliation(s)
- Alexandre Blanckaert
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, United States
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, United States
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21
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De Santis V, Quadroni S, Britton RJ, Carosi A, Gutmann Roberts C, Lorenzoni M, Crosa G, Zaccara S. Biological and trophic consequences of genetic introgression between endemic and invasive Barbus fishes. Biol Invasions 2021;:1-18. [PMID: 34054333 DOI: 10.1007/s10530-021-02577-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 05/13/2021] [Indexed: 12/02/2022]
Abstract
Genetic introgression with native species is recognized as a detrimental impact resulting from biological invasions involving taxonomically similar invaders. Whilst the underlying genetic mechanisms are increasingly understood, the ecological consequences of introgression are relatively less studied, despite their utility for increasing knowledge on how invasion impacts can manifest. Here, the ecological consequences of genetic introgression from an invasive congener were tested using the endemic barbel populations of central Italy, where the invader was the European barbel Barbus barbus. Four populations of native Barbus species (B. plebejus and B. tyberinus) were studied: two purebred and two completely introgressed with alien B. barbus. Across the four populations, differences in their biological traits (growth, body condition and population demographic structure) and trophic ecology (gut content analysis and stable isotope analysis) were tested. While all populations had similar body condition and were dominated by fish up to 2 years of age, the introgressed fish had substantially greater lengths at the same age, with maximum lengths 410–460 mm in hybrids versus 340–360 mm in native purebred barbel. The population characterized by the highest number of introgressed B. barbus alleles (81 %) had the largest trophic niche and a substantially lower trophic position than the other populations through its exploitation of a wider range of resources (e.g. small fishes and plants). These results attest that the genetic introgression of an invasive congener with native species can result in substantial ecological consequences, including the potential for cascading effects.
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22
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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] [What about the content of this article? (0)] [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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23
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Barke BH, Karbstein K, Daubert M, Hörandl E. The relation of meiotic behaviour to hybridity, polyploidy and apomixis in the Ranunculus auricomus complex (Ranunculaceae). BMC Plant Biol 2020; 20:523. [PMID: 33203395 PMCID: PMC7672892 DOI: 10.1186/s12870-020-02654-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/20/2020] [Indexed: 05/23/2023]
Abstract
BACKGROUND Hybridization and polyploidization are powerful evolutionary factors that are associated with manifold developmental changes in plants such as irregular progression of meiosis and sporogenesis. The emergence of apomixis, which is asexual reproduction via seeds, is supposed to be connected to these factors and was often regarded as an escape from hybrid sterility. However, the functional trigger of apomixis is still unclear. Recently formed di- and polyploid Ranunculus hybrids, as well as their parental species were analysed for their modes of mega- and microsporogenesis by microscopy. Chromosomal configurations during male meiosis were screened for abnormalities. Meiotic and developmental abnormalities were documented qualitatively and collected quantitatively for statistical evaluations. RESULTS Allopolyploids showed significantly higher frequencies of erroneous microsporogenesis than homoploid hybrid plants. Among diploids, F2 hybrids had significantly more disturbed meiosis than F1 hybrids and parental plants. Chromosomal aberrations included laggard chromosomes, chromatin bridges and disoriented spindle activities. Failure of megasporogenesis appeared to be much more frequent in than of microsporogenesis is correlated to apomixis onset. CONCLUSIONS Results suggest diverging selective pressures on female and male sporogenesis, with only minor effects of hybridity on microsporogenesis, but fatal effects on the course of megasporogenesis. Hence, pollen development continues without major alterations, while selection will favour apomixis as alternative to the female meiotic pathway. Relation of investigated errors of megasporogenesis with the observed occurrence of apospory in Ranunculus hybrids identifies disturbed female meiosis as potential elicitor of apomixis in order to rescue these plants from hybrid sterility. Male meiotic disturbance appears to be stronger in neopolyploids than in homoploid hybrids, while disturbances of megasporogenesis were not ploidy-dependent.
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Affiliation(s)
- Birthe H Barke
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany.
| | - Kevin Karbstein
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
| | - Mareike Daubert
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
- Present Address: Carl von Ossietzky University, Institute of Biology and Environmental Sciences, Carl von Ossietzky Straße 9-11, D-26129, Oldenburg, Germany
| | - Elvira Hörandl
- Department of Systematics, Biodiversity and Evolution of Plants, Albrecht-von-Haller Institute for Plant Sciences, University of Goettingen, Untere Karspuele 2, D-37073, Goettingen, Germany
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24
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Gao L, Rieseberg LH. While neither universally applicable nor practical operationally, the biological species concept continues to offer a compelling framework for studying species and speciation. Natl Sci Rev 2020; 7:1398-1400. [PMID: 34692167 PMCID: PMC8288963 DOI: 10.1093/nsr/nwaa108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Lexuan Gao
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, China
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Canada
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Canada
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25
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Chaturvedi S, Lucas LK, Buerkle CA, Fordyce JA, Forister ML, Nice CC, Gompert Z. Recent hybrids recapitulate ancient hybrid outcomes. Nat Commun 2020; 11:2179. [PMID: 32358487 PMCID: PMC7195404 DOI: 10.1038/s41467-020-15641-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/20/2020] [Indexed: 02/07/2023] Open
Abstract
Genomic outcomes of hybridization depend on selection and recombination in hybrids. Whether these processes have similar effects on hybrid genome composition in contemporary hybrid zones versus ancient hybrid lineages is unknown. Here we show that patterns of introgression in a contemporary hybrid zone in Lycaeides butterflies predict patterns of ancestry in geographically adjacent, older hybrid populations. We find a particularly striking lack of ancestry from one of the hybridizing taxa, Lycaeides melissa, on the Z chromosome in both the old and contemporary hybrids. The same pattern of reduced L. melissa ancestry on the Z chromosome is seen in two other ancient hybrid lineages. More generally, we find that patterns of ancestry in old or ancient hybrids are remarkably predictable from contemporary hybrids, which suggests selection and recombination affect hybrid genomes in a similar way across disparate time scales and during distinct stages of speciation and species breakdown.
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Affiliation(s)
- Samridhi Chaturvedi
- Department of Biology, Utah State University, Logan, UT, 84322, USA
- Ecology Center, Utah State University, Logan, UT, 84322, USA
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Lauren K Lucas
- Department of Biology, Utah State University, Logan, UT, 84322, USA
| | - C Alex Buerkle
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
| | - James A Fordyce
- Department of Ecology & Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | | | - Chris C Nice
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA
| | - Zachariah Gompert
- Department of Biology, Utah State University, Logan, UT, 84322, USA.
- Ecology Center, Utah State University, Logan, UT, 84322, USA.
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26
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Abstract
Comparative genomic approaches are increasingly being used to study the evolution of reproductive barriers in nonmodel species. Although numerous studies have examined prezygotic isolation in darters (Percidae), investigations into postzygotic barriers have remained rare due to long generation times and a lack of genomic resources. Orangethroat and rainbow darters naturally hybridize and provide a remarkable example of male-driven speciation via character displacement. Backcross hybrids suffer from high mortality, which appears to promote behavioral isolation in sympatry. To investigate the genomic architecture of postzygotic isolation, we used Illumina and PacBio sequencing to generate a chromosome-level, annotated assembly of the orangethroat darter genome and high-density linkage maps for orangethroat and rainbow darters. We also analyzed genome-wide RADseq data from wild-caught adults of both species and laboratory-generated backcrosses to identify genomic regions associated with hybrid incompatibles. Several putative chromosomal translocations and inversions were observed between orangethroat and rainbow darters, suggesting structural rearrangements may underlie postzygotic isolation. We also found evidence of selection against recombinant haplotypes and transmission ratio distortion in backcross hybrid genomes, providing further insight into the genomic architecture of genetic incompatibilities. Notably, regions with high levels of genetic divergence between species were enriched for genes associated with developmental and meiotic processes, providing strong candidates for postzygotic isolating barriers. These findings mark significant contributions to our understanding of the genetic basis of reproductive isolation between species undergoing character displacement. Furthermore, the genomic resources presented here will be instrumental for studying speciation in darters, the most diverse vertebrate group in North America.
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Affiliation(s)
- Rachel L Moran
- Program in Ecology, Evolution, and Conservation Biology, Department of Animal Biology, University of Illinois at Urbana-Champaign, Champaign, IL
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN
| | - Julian M Catchen
- Program in Ecology, Evolution, and Conservation Biology, Department of Animal Biology, University of Illinois at Urbana-Champaign, Champaign, IL
| | - Rebecca C Fuller
- Program in Ecology, Evolution, and Conservation Biology, Department of Animal Biology, University of Illinois at Urbana-Champaign, Champaign, IL
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Schultze N, Laufer H, Kindler C, Fritz U. Distribution and hybridisation of barred and common grass snakes (Natrix helvetica, N. natrix) in Baden-Württemberg, South-western Germany. HERPETOZOA 2019. [DOI: 10.3897/herpetozoa.32.e38897] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The distribution and hybridisation zone of the two grass snake species occurring in the German state of Baden-Württemberg are described, based on genetic data from maternally inherited mitochondrial DNA (mtDNA, up to 1983 bp) and biparentally inherited microsatellite DNA (13 loci). In agreement with previously published morphological evidence, the barred grass snake (Natrix helvetica) occurs in the Upper Rhine Valley and the Black Forest, while the common grass snake (N. natrix, ‘yellow lineage’) is distributed across the remaining, more eastern parts of Baden-Württemberg. Cline analyses across two transects running through the region of Karlsruhe and the Black Forest indicate that the hybrid zone is similarly narrow here as in the previously characterised stretch near Lake Constance. With respect to nuclear DNA, the Black Forest constitutes no impediment to gene flow in comparison with lowland regions (Karlsruhe, Lake Constance). However, on the eastern slope of the Black Forest, the abrupt replacement of mtDNA of N. helvetica by that of N. natrix indicates male-mediated gene flow and that the Black Forest represents a dispersal barrier for female grass snakes.
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Coyle AE, Voss ER, Tepolt CK, Carlon DB. Mitochondrial genotype influences the response to cold stress in the European green crab, Carcinus maenas. J Exp Biol 2019; 222:jeb203521. [PMID: 31285243 DOI: 10.1242/jeb.203521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/03/2019] [Indexed: 12/20/2022]
Abstract
Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear single nucleotide polymorphisms (SNPs) representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5°C that was sex specific: haplotypes originally from northern Europe gave male crabs an advantage while there was no haplotype effect on righting in female crabs. By contrast, the two nuclear SNPs that were significant outliers in a comparison between northern and southern C. maenas populations had no effect on righting response at low temperature. These results add C. maenas to the shortlist of ectotherms in which mitochondrial variation has been shown to affect thermal tolerance, and suggest that natural selection is shaping the structure of the hybrid zone across the Gulf of Maine. Our limited genomic sampling does not eliminate the strong possibility that mito-nuclear co-adaptation may play a role in the differences in thermal phenotypes documented here. Linkage between mitochondrial genotype and thermal tolerance suggests a role for local adaptation in promoting the spread of invasive populations of C. maenas around the world.
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Affiliation(s)
- Aspen E Coyle
- Department of Biology & Schiller Coastal Studies Center, Bowdoin College, Brunswick, ME 04011, USA
| | - Erin R Voss
- Department of Biology & Schiller Coastal Studies Center, Bowdoin College, Brunswick, ME 04011, USA
| | - Carolyn K Tepolt
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - David B Carlon
- Department of Biology & Schiller Coastal Studies Center, Bowdoin College, Brunswick, ME 04011, USA
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Bresadola L, Caseys C, Castiglione S, Buerkle CA, Wegmann D, Lexer C. Admixture mapping in interspecific Populus hybrids identifies classes of genomic architectures for phytochemical, morphological and growth traits. New Phytol 2019; 223:2076-2089. [PMID: 31104343 PMCID: PMC6771622 DOI: 10.1111/nph.15930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 05/06/2019] [Indexed: 05/03/2023]
Abstract
The genomic architecture of functionally important traits is key to understanding the maintenance of reproductive barriers and trait differences when divergent populations or species hybridize. We conducted a genome-wide association study (GWAS) to study trait architecture in natural hybrids of two ecologically divergent Populus species. We genotyped 472 seedlings from a natural hybrid zone of Populus alba and Populus tremula for genome-wide markers from reduced representation sequencing, phenotyped the plants in common gardens for 46 phytochemical (phenylpropanoid), morphological and growth traits, and used a Bayesian polygenic model for mapping. We detected three classes of genomic architectures: traits with finite, detectable associations of genetic loci with phenotypic variation in addition to highly polygenic heritability; traits with indications for polygenic heritability only; and traits with no detectable heritability. For the first class, we identified genome regions with plausible candidate genes for phenylpropanoid biosynthesis or its regulation, including MYB transcription factors and glycosyl transferases. GWAS in natural, recombinant hybrids represent a promising step towards resolving the genomic architecture of phenotypic traits in long-lived species. This facilitates the fine-mapping and subsequent functional characterization of genes and networks causing differences in hybrid performance and fitness.
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Affiliation(s)
- Luisa Bresadola
- Department of BiologyUniversity of FribourgChemin du Musée 101700FribourgSwitzerland
| | - Céline Caseys
- Department of BiologyUniversity of FribourgChemin du Musée 101700FribourgSwitzerland
- Department of Plant SciencesUniversity of California DavisOne Shields AvenueDavisCA95616USA
| | - Stefano Castiglione
- Department of Chemistry and Biology ‘A. Zambelli’University of SalernoVia Giovanni Paolo II 13284084Fisciano, SalernoItaly
| | - C. Alex Buerkle
- Department of BotanyUniversity of Wyoming1000 E. University Ave.LaramieWY82071USA
| | - Daniel Wegmann
- Department of BiologyUniversity of FribourgChemin du Musée 101700FribourgSwitzerland
- Swiss Institute of Bioinformatics1700FribourgSwitzerland
| | - Christian Lexer
- Department of BiologyUniversity of FribourgChemin du Musée 101700FribourgSwitzerland
- Department of Botany and Biodiversity ResearchFaculty of Life SciencesUniversity of ViennaRennweg 12A‐1030ViennaAustria
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Abstract
Introgression is emerging as an important source of novel genetic variation, alongside standing variation and mutation. It is adaptive when such introgressed alleles are maintained by natural selection. Recently, there has been an explosion in the number of studies on adaptive introgression. In this review, we take a plant perspective centred on four lines of evidence: (i) introgression, (ii) selection, (iii) phenotype and (iv) fitness. While advances in genomics have contributed to our understanding of introgression and porous species boundaries (task 1), and the detection of signatures of selection in introgression (task 2), the investigation of adaptive introgression critically requires links to phenotypic variation and fitness (tasks 3 and 4). We also discuss the conservation implications of adaptive introgression in the face of climate change. Adaptive introgression is particularly important in rapidly changing environments, when standing genetic variation and mutation alone may only offer limited potential for adaptation. We conclude that clarifying the magnitude and fitness effects of introgression with improved statistical techniques, coupled with phenotypic evidence, has great potential for conservation and management efforts.
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Affiliation(s)
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Quentin C B Cronk
- Department of Botany, University of British Columbia, Vancouver, Canada
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Ruiz-García M, Pinedo-Castro M, Shostell JM. Mitogenomics of the jaguarundi (Puma yagouaroundi, Felidae, Carnivora): Disagreement between morphological subspecies and molecular data. Mamm Biol 2018. [DOI: 10.1016/j.mambio.2018.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Doellman MM, Ragland GJ, Hood GR, Meyers PJ, Egan SP, Powell THQ, Lazorchak P, Glover MM, Tait C, Schuler H, Hahn DA, Berlocher SH, Smith JJ, Nosil P, Feder JL. Genomic Differentiation during Speciation-with-Gene-Flow: Comparing Geographic and Host-Related Variation in Divergent Life History Adaptation in Rhagoletis pomonella. Genes (Basel) 2018; 9:E262. [PMID: 29783692 DOI: 10.3390/genes9050262] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 05/09/2018] [Accepted: 05/09/2018] [Indexed: 12/16/2022] Open
Abstract
A major goal of evolutionary biology is to understand how variation within populations gets partitioned into differences between reproductively isolated species. Here, we examine the degree to which diapause life history timing, a critical adaptation promoting population divergence, explains geographic and host-related genetic variation in ancestral hawthorn and recently derived apple-infesting races of Rhagoletis pomonella. Our strategy involved combining experiments on two different aspects of diapause (initial diapause intensity and adult eclosion time) with a geographic survey of genomic variation across four sites where apple and hawthorn flies co-occur from north to south in the Midwestern USA. The results demonstrated that the majority of the genome showing significant geographic and host-related variation can be accounted for by initial diapause intensity and eclosion time. Local genomic differences between sympatric apple and hawthorn flies were subsumed within broader geographic clines; allele frequency differences within the races across the Midwest were two to three-fold greater than those between the races in sympatry. As a result, sympatric apple and hawthorn populations displayed more limited genomic clustering compared to geographic populations within the races. The findings suggest that with reduced gene flow and increased selection on diapause equivalent to that seen between geographic sites, the host races may be recognized as different genotypic entities in sympatry, and perhaps species, a hypothesis requiring future genomic analysis of related sibling species to R. pomonella to test. Our findings concerning the way selection and geography interplay could be of broad significance for many cases of earlier stages of divergence-with-gene flow, including (1) where only modest increases in geographic isolation and the strength of selection may greatly impact genetic coupling and (2) the dynamics of how spatial and temporal standing variation is extracted by selection to generate differences between new and discrete units of biodiversity.
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Schumer M, Xu C, Powell DL, Durvasula A, Skov L, Holland C, Blazier JC, Sankararaman S, Andolfatto P, Rosenthal GG, Przeworski M. Natural selection interacts with recombination to shape the evolution of hybrid genomes. Science 2018; 360:656-660. [PMID: 29674434 PMCID: PMC6069607 DOI: 10.1126/science.aar3684] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 03/23/2018] [Indexed: 12/29/2022]
Abstract
To investigate the consequences of hybridization between species, we studied three replicate hybrid populations that formed naturally between two swordtail fish species, estimating their fine-scale genetic map and inferring ancestry along the genomes of 690 individuals. In all three populations, ancestry from the "minor" parental species is more common in regions of high recombination and where there is linkage to fewer putative targets of selection. The same patterns are apparent in a reanalysis of human and archaic admixture. These results support models in which ancestry from the minor parental species is more likely to persist when rapidly uncoupled from alleles that are deleterious in hybrids. Our analyses further indicate that selection on swordtail hybrids stems predominantly from deleterious combinations of epistatically interacting alleles.
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Affiliation(s)
- Molly Schumer
- Howard Hughes Medical Institute (HHMI), Boston, MA, USA.
- Harvard Society of Fellows, Harvard University, Cambridge, MA, USA
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
| | - Chenling Xu
- Center for Computational Biology, University of California at Berkeley, Berkeley, CA, USA
| | - Daniel L Powell
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Arun Durvasula
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Laurits Skov
- Bioinformatics Research Centre, Aarhus University, Aarhus, Denmark
| | - Chris Holland
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - John C Blazier
- Department of Biology, Texas A&M University, College Station, TX, USA
- Texas A&M Institute for Genome Sciences and Society, College Station, TX, USA
| | - Sriram Sankararaman
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Computer Science, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peter Andolfatto
- Department of Ecology and Evolutionary Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Gil G Rosenthal
- Centro de Investigaciones Científicas de las Huastecas "Aguazarca," Calnali, Hidalgo, Mexico
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Molly Przeworski
- Department of Biological Sciences, Columbia University, New York, NY, USA.
- Department of Systems Biology, Columbia University, New York, NY, USA
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Sharbrough J, Havird JC, Noe GR, Warren JM, Sloan DB. The Mitonuclear Dimension of Neanderthal and Denisovan Ancestry in Modern Human Genomes. Genome Biol Evol 2018; 9:1567-1581. [PMID: 28854627 PMCID: PMC5509035 DOI: 10.1093/gbe/evx114] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2017] [Indexed: 12/15/2022] Open
Abstract
Some human populations interbred with Neanderthals and Denisovans, resulting in substantial contributions to modern-human genomes. Therefore, it is now possible to use genomic data to investigate mechanisms that shaped historical gene flow between humans and our closest hominin relatives. More generally, in eukaryotes, mitonuclear interactions have been argued to play a disproportionate role in generating reproductive isolation. There is no evidence of mtDNA introgression into modern human populations, which means that all introgressed nuclear alleles from archaic hominins must function on a modern-human mitochondrial background. Therefore, mitonuclear interactions are also potentially relevant to hominin evolution. We performed a detailed accounting of mtDNA divergence among hominin lineages and used population-genomic data to test the hypothesis that mitonuclear incompatibilities have preferentially restricted the introgression of nuclear genes with mitochondrial functions. We found a small but significant underrepresentation of introgressed Neanderthal alleles at such nuclear loci. Structural analyses of mitochondrial enzyme complexes revealed that these effects are unlikely to be mediated by physically interacting sites in mitochondrial and nuclear gene products. We did not detect any underrepresentation of introgressed Denisovan alleles at mitochondrial-targeted loci, but this may reflect reduced power because locus-specific estimates of Denisovan introgression are more conservative. Overall, we conclude that genes involved in mitochondrial function may have been subject to distinct selection pressures during the history of introgression from archaic hominins but that mitonuclear incompatibilities have had, at most, a small role in shaping genome-wide introgression patterns, perhaps because of limited functional divergence in mtDNA and interacting nuclear genes.
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Affiliation(s)
- Joel Sharbrough
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Justin C Havird
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Gregory R Noe
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Jessica M Warren
- Department of Biology, Colorado State University, Fort Collins, CO
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO
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35
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Rajeh A, Lv J, Lin Z. Heterogeneous rates of genome rearrangement contributed to the disparity of species richness in Ascomycota. BMC Genomics 2018; 19:282. [PMID: 29690866 PMCID: PMC5937819 DOI: 10.1186/s12864-018-4683-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/16/2018] [Indexed: 01/06/2023] Open
Abstract
Background Chromosomal rearrangements have been shown to facilitate speciation through creating a barrier of gene flow. However, it is not known whether heterogeneous rates of chromosomal rearrangement at the genome scale contributed to the huge disparity of species richness among different groups of organisms, which is one of the most remarkable and pervasive patterns on Earth. The largest fungal phylum Ascomycota is an ideal study system to address this question because it comprises three subphyla (Saccharomycotina, Taphrinomycotina, and Pezizomycotina) whose species numbers differ by two orders of magnitude (59,000, 1000, and 150 respectively). Results We quantified rates of genome rearrangement for 71 Ascomycota species that have well-assembled genomes. The rates of inter-species genome rearrangement, which were inferred based on the divergence rates of gene order, are positively correlated with species richness at both ranks of subphylum and class in Ascomycota. This finding is further supported by our quantification of intra-species rearrangement rates based on paired-end genome sequencing data of 216 strains from three representative species, suggesting a difference of intrinsic genome instability among Ascomycota lineages. Our data also show that different rates of imbalanced rearrangements, such as deletions, are a major contributor to the heterogenous rearrangement rates. Conclusions Various lines of evidence in this study support that a higher rate of rearrangement at the genome scale might have accelerated the speciation process and increased species richness during the evolution of Ascomycota species. Our findings provide a plausible explanation for the species disparity among Ascomycota lineages, which will be valuable to unravel the underlying causes for the huge disparity of species richness in various taxonomic groups. Electronic supplementary material The online version of this article (10.1186/s12864-018-4683-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ahmad Rajeh
- Department of Biology, Saint Louis University, St. Louis, MO, 63103, USA.,Department of Computer Science, Saint Louis University, St. Louis, MO, 63103, USA
| | - Jie Lv
- Department of BioSciences, Rice University, Houston, TX, 77005, USA
| | - Zhenguo Lin
- Department of Biology, Saint Louis University, St. Louis, MO, 63103, USA.
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Schmidt L, Fischer M, Oja T. Two closely related species differ in their regional genetic differentiation despite admixing. AoB Plants 2018; 10:ply007. [PMID: 29479408 PMCID: PMC5817946 DOI: 10.1093/aobpla/ply007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/09/2018] [Indexed: 06/08/2023]
Abstract
Regional genetic differentiation within species is often addressed in evolutionary ecology and conservation biology. Here, we address regional differentiation in two closely related hybridizing taxa, the perennial sedges Carex flava and C. viridula and their hybrid C. × subviridula in 37 populations in the north and centre of their distribution range in Europe (Estonia, Lowland (<1000 m a.s.l.) and Highland Switzerland) using 10 putative microsatellite loci. We ask whether regional differentiation was larger in the less common taxon C. viridula or whether, possibly due to hybridization, it was similar between taxa. Our results showed similar, low to moderate genetic diversity for the three studied taxa. In total, we found 12 regional species-specific alleles. Analysis of molecular variance (AMOVA), STRUCTURE and multidimensional scaling analysis showed regional structure in genetic variation, where intraspecific differentiation between regions was lower for C. flava (AMOVA: 6.84 %) than for C. viridula (20.77 %) or C. × subviridula (18.27 %) populations. Hybrids differed from the parental taxa in the two regions where they occurred, i.e. in Estonia and Lowland Switzerland. We conclude that C. flava and C. viridula clearly differ from each other genetically, that there is pronounced regional differentiation and that, despite hybridization, this regional differentiation is more pronounced in the less common taxon, C. viridula. We encourage future studies on hybridizing taxa to work with plant populations from more than one region.
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Affiliation(s)
- Lisanna Schmidt
- Institute of Ecology and Earth Sciences, Department of Botany, University of Tartu, Tartu, Estonia
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Markus Fischer
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
- Botanical Garden, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Tatjana Oja
- Institute of Ecology and Earth Sciences, Department of Botany, University of Tartu, Tartu, Estonia
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Reeve J, Ortiz-Barrientos D, Engelstädter J. The evolution of recombination rates in finite populations during ecological speciation. Proc Biol Sci 2017; 283:rspb.2016.1243. [PMID: 27798297 DOI: 10.1098/rspb.2016.1243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 10/04/2016] [Indexed: 11/12/2022] Open
Abstract
Recombination can impede ecological speciation with gene flow by mixing locally adapted genotypes with maladapted migrant genotypes from a divergent population. In such a scenario, suppression of recombination can be selectively favoured. However, in finite populations evolving under the influence of random genetic drift, recombination can also facilitate adaptation by reducing Hill-Robertson interference between loci under selection. In this case, increased recombination rates can be favoured. Although these two major effects on recombination have been studied individually, their joint effect on ecological speciation with gene flow remains unexplored. Using a mathematical model, we investigated the evolution of recombination rates in two finite populations that exchange migrants while adapting to contrasting environments. Our results indicate a two-step dynamic where increased recombination is first favoured (in response to the Hill-Robertson effect), and then disfavoured, as the cost of recombining locally with maladapted migrant genotypes increases over time (the maladaptive gene flow effect). In larger populations, a stronger initial benefit for recombination was observed, whereas high migration rates intensify the long-term cost of recombination. These dynamics may have important implications for our understanding of the conditions that facilitate incipient speciation with gene flow and the evolution of recombination in finite populations.
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Affiliation(s)
- James Reeve
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Daniel Ortiz-Barrientos
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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Mondon A, Owens GL, Poverene M, Cantamutto M, Rieseberg LH. Gene flow in Argentinian sunflowers as revealed by genotyping-by-sequencing data. Evol Appl 2017; 11:193-204. [PMID: 29387155 PMCID: PMC5775495 DOI: 10.1111/eva.12527] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 07/26/2017] [Indexed: 01/04/2023] Open
Abstract
Gene flow can have several different applied consequences, ranging from extinction to the escape of transgenes to the evolution of weedy or invasive lineages. Here, we describe patterns of hybridization and gene flow involving domesticated and wild sunflowers in Argentina. To address the risks of introgression of variants from the cultivated sunflower into invasive wild Helianthus, we used genotyping‐by‐sequencing (GBS) to genotype 182 samples from 11 sites in Argentina, along with previously published data from samples from the native range (North America), to determine the native source populations of the Argentinian samples and to detect admixture. We unexpectedly discovered two distinctive forms of H. petiolaris in Argentina, one from H. petiolaris subsp. petiolaris as expected, but the other from an unknown source. Extensive admixture was observed among Argentinian sunflowers, largely confirming phenotypic predictions. While many hybrids are F1s, there were signals consistent with introgression from the domesticated sunflower into H. petiolaris. Whether this introgression is incidental or a causal driver of invasiveness is not yet clear, but it seems likely that genes found in the domesticated sunflower genome (whether engineered or not) will quickly find their way into wild Argentinian sunflower populations.
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Affiliation(s)
- Ana Mondon
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) CCT Bahía Blanca Provincia de Buenos Aires Argentina
| | - Gregory L Owens
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
| | - Mónica Poverene
- Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) CCT Bahía Blanca Provincia de Buenos Aires Argentina.,Dpto. Agronomía Universidad Nacional del Sur (UNS) Bahía Blanca Argentina
| | - Miguel Cantamutto
- Estación Experimental Agropecuaria Instituto Nacional de Tecnología Agropecuaria (INTA) Hilario Ascasubi Argentina
| | - Loren H Rieseberg
- Department of Botany and Biodiversity Research Centre University of British Columbia Vancouver BC Canada
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Blackburn GS, Brunet BMT, Muirhead K, Cusson M, Béliveau C, Levesque RC, Lumley LM, Sperling FAH. Distinct sources of gene flow produce contrasting population genetic dynamics at different range boundaries of aChoristoneurabudworm. Mol Ecol 2017; 26:6666-6684. [DOI: 10.1111/mec.14386] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 09/26/2017] [Accepted: 10/07/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Gwylim S. Blackburn
- Department of Biological Sciences; CW405 Biosciences Centre; University of Alberta; Edmonton AB Canada
- Laurentian Forestry Centre; Natural Resources Canada; Canadian Forest Service; Quebec City QC Canada
- Institut de Biologie Intégrative et des Systèmes (IBIS); Université Laval; Québec QC Canada
| | - Bryan M. T. Brunet
- Department of Biological Sciences; CW405 Biosciences Centre; University of Alberta; Edmonton AB Canada
| | - Kevin Muirhead
- Department of Biological Sciences; CW405 Biosciences Centre; University of Alberta; Edmonton AB Canada
| | - Michel Cusson
- Laurentian Forestry Centre; Natural Resources Canada; Canadian Forest Service; Quebec City QC Canada
| | - Catherine Béliveau
- Laurentian Forestry Centre; Natural Resources Canada; Canadian Forest Service; Quebec City QC Canada
| | - Roger C. Levesque
- Institut de Biologie Intégrative et des Systèmes (IBIS); Université Laval; Québec QC Canada
| | - Lisa M. Lumley
- Department of Biological Sciences; CW405 Biosciences Centre; University of Alberta; Edmonton AB Canada
- Laurentian Forestry Centre; Natural Resources Canada; Canadian Forest Service; Quebec City QC Canada
| | - Felix A. H. Sperling
- Department of Biological Sciences; CW405 Biosciences Centre; University of Alberta; Edmonton AB Canada
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Affiliation(s)
- Zachariah Gompert
- Department of Biology and Ecology Center, Utah State University, Logan, Utah 84322
| | - Elizabeth G. Mandeville
- Department of Botany and Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, Laramie, Wyoming 82071
| | - C. Alex Buerkle
- Department of Botany and Program in Ecology, University of Wyoming, Laramie, Wyoming 82071
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Delahaie B, Cornuault J, Masson C, Bertrand JAM, Bourgeois YXC, Milá B, Thébaud C. Narrow hybrid zones in spite of very low population differentiation in neutral markers in an island bird species complex. J Evol Biol 2017; 30:2132-2145. [DOI: 10.1111/jeb.13177] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/26/2017] [Accepted: 09/07/2017] [Indexed: 02/06/2023]
Affiliation(s)
- B. Delahaie
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
- Centre d'Ecologie Fonctionnelle et Evolutive; CNRS-UMR5175 CEFE; Montpellier France
| | - J. Cornuault
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - C. Masson
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - J. A. M. Bertrand
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - Y. X. C. Bourgeois
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
| | - B. Milá
- National Museum of Natural Sciences; Spanish National Research Council (CSIC); Madrid Spain
| | - C. Thébaud
- Laboratoire Évolution et Diversité Biologique (EDB); UMR 5174 Centre National de la Recherche Scientifique (CNRS) - Université Paul Sabatier - Ecole Nationale de Formation Agronomique (ENFA); Toulouse France
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Fouet C, Kamdem C, Gamez S, White BJ. Genomic insights into adaptive divergence and speciation among malaria vectors of the Anopheles nili group. Evol Appl 2017; 10:897-906. [PMID: 29151881 PMCID: PMC5680430 DOI: 10.1111/eva.12492] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/27/2017] [Indexed: 01/16/2023] Open
Abstract
Ongoing speciation in the most important African malaria vectors gives rise to cryptic populations, which differ remarkably in their behavior, ecology, and capacity to vector malaria parasites. Understanding the population structure and the drivers of genetic differentiation among mosquitoes is crucial for effective disease control because heterogeneity within vector species contributes to variability in malaria cases and allow fractions of populations to escape control efforts. To examine population structure and the potential impacts of recent large-scale control interventions, we have investigated the genomic patterns of differentiation in mosquitoes belonging to the Anopheles nili group-a large taxonomic group that diverged ~3 Myr ago. Using 4,343 single nucleotide polymorphisms (SNPs), we detected strong population structure characterized by high-FST values between multiple divergent populations adapted to different habitats within the Central African rainforest. Delineating the cryptic species within the Anopheles nili group is challenging due to incongruence between morphology, ribosomal DNA, and SNP markers consistent with incomplete lineage sorting and/or interspecific gene flow. A very high proportion of loci are fixed (FST = 1) within the genome of putative species, which suggests that ecological and/or reproductive barriers are maintained by strong selection on a substantial number of genes.
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Affiliation(s)
- Caroline Fouet
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Colince Kamdem
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Stephanie Gamez
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
| | - Bradley J. White
- Department of EntomologyUniversity of CaliforniaRiversideCAUSA
- Center for Disease Vector ResearchInstitute for Integrative Genome BiologyUniversity of CaliforniaRiversideCAUSA
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Abstract
The interplay of divergent selection and gene flow is key to understanding how populations adapt to local environments and how new species form. Here, we use DNA polymorphism data and genome-wide variation in recombination rate to jointly infer the strength and timing of selection, as well as the baseline level of gene flow under various demographic scenarios. We model how divergent selection leads to a genome-wide negative correlation between recombination rate and genetic differentiation among populations. Our theory shows that the selection density (i.e., the selection coefficient per base pair) is a key parameter underlying this relationship. We then develop a procedure for parameter estimation that accounts for the confounding effect of background selection. Applying this method to two datasets from Mimulus guttatus, we infer a strong signal of adaptive divergence in the face of gene flow between populations growing on and off phytotoxic serpentine soils. However, the genome-wide intensity of this selection is not exceptional compared with what M. guttatus populations may typically experience when adapting to local conditions. We also find that selection against genome-wide introgression from the selfing sister species M. nasutus has acted to maintain a barrier between these two species over at least the last 250 ky. Our study provides a theoretical framework for linking genome-wide patterns of divergence and recombination with the underlying evolutionary mechanisms that drive this differentiation.
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Affiliation(s)
- Simon Aeschbacher
- Department of Evolution and Ecology, University of California, Davis, CA 95616;
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
- Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | | | - John H Willis
- Department of Biology, Duke University, Durham, NC 27708
| | - Graham Coop
- Department of Evolution and Ecology, University of California, Davis, CA 95616
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45
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de Lafontaine G, Bousquet J. Asymmetry matters: A genomic assessment of directional biases in gene flow between hybridizing spruces. Ecol Evol 2017; 7:3883-3893. [PMID: 28616185 PMCID: PMC5468134 DOI: 10.1002/ece3.2682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/16/2016] [Accepted: 11/20/2016] [Indexed: 01/08/2023] Open
Abstract
Assessing directional bias in interspecific gene flow might be important in determining the evolutionary trajectory of closely related species pairs. Using a set of 300 single nucleotide polymorphisms (SNPs) having variable propensity to cross species boundary, we evaluated the genomic extent and direction of interspecific gene flow in a progenitor‐derivative spruce species pair (black spruce and red spruce). A higher rate of gene flow was found from black spruce toward red spruce purebreds than vice versa. This asymmetry could reflect the historical gene flow between the two taxa at the time of species inception and during postglacial colonization. A clear asymmetry in introgression was depicted by a greater gene flow between red spruce and hybrids than between black spruce and hybrids. While backcrossing toward red spruce was invariably high across the genome, the actual species boundary is between hybrids and black spruce where gene flow is impeded at those genomic regions impermeable to introgression. Associations between hybrid index and climatic variables (total annual precipitation and mean annual temperature) were tested, as these might indicate a role for exogenous selection in maintaining the species boundary. While an apparent association was found between the hybrid index and precipitation, it collapsed when considered in light of the directional bias in interspecific gene flow. Hence, considering asymmetrical patterns of introgression allowed us to falsify an apparent role for exogenous selection. Although this was not formerly tested here, we suggest that this pattern could result from asymmetrical endogenous selection, a contention that deserves further investigations.
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Affiliation(s)
- Guillaume de Lafontaine
- Canada Research Chair in Forest Genomics Centre for Forest Research and Institute of Systems and Integrative Biology Université Laval Québec QC Canada.,Department of Plant Biology University of Illinois Urbana IL USA
| | - Jean Bousquet
- Canada Research Chair in Forest Genomics Centre for Forest Research and Institute of Systems and Integrative Biology Université Laval Québec QC Canada
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46
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Stacy EA, Paritosh B, Johnson MA, Price DK. Incipient ecological speciation between successional varieties of a dominant tree involves intrinsic postzygotic isolating barriers. Ecol Evol 2017; 7:2501-2512. [PMID: 28428842 PMCID: PMC5395442 DOI: 10.1002/ece3.2867] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/06/2017] [Accepted: 02/06/2017] [Indexed: 01/18/2023] Open
Abstract
Whereas disruptive selection imposed by heterogeneous environments can lead to the evolution of extrinsic isolating barriers between diverging populations, the evolution of intrinsic postzygotic barriers through divergent selection is less certain. Long-lived species such as trees may be especially slow to evolve intrinsic isolating barriers. We examined postpollination reproductive isolating barriers below the species boundary, in an ephemeral hybrid zone between two successional varieties of the landscape-dominant Hawaiian tree, Metrosideros polymorpha, on volcanically active Hawai'i Island. These archipelago-wide sympatric varieties show the weakest neutral genetic divergence of any taxon pair on Hawai'i Island but significant morphological and ecological differentiation consistent with adaptation to new and old lava flows. Cross-fertility between varieties was high and included heterosis of F1 hybrids at the seed germination stage, consistent with a substantial genetic load apparent within varieties through low self-fertility and a lack of self-pollen discrimination. However, a partial, but significant, barrier was observed in the form of reduced female and male fertility of hybrids, especially backcross hybrids, consistent with the accumulation of genetic incompatibilities between varieties. These results suggest that partial intrinsic postzygotic barriers can arise through disruptive selection acting on large, hybridizing populations of a long-lived species.
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Affiliation(s)
- Elizabeth A Stacy
- Department of Biology University of Hawai'i Hilo Hilo HI USA.,Tropical Conservation Biology and Environmental Science Graduate Program University of Hawai'i Hilo Hilo HI USA.,Present address: School of Life Sciences University of Nevada, Las Vegas 4505 S Maryland Pkwy Las Vegas NV 89154 USA
| | - Bhama Paritosh
- Department of Biology University of Hawai'i Hilo Hilo HI USA
| | - Melissa A Johnson
- Tropical Conservation Biology and Environmental Science Graduate Program University of Hawai'i Hilo Hilo HI USA.,Present address: Department of Botany Claremont Graduate University, Rancho Santa Ana Botanic Garden 1500 N. College Ave. Claremont CA 91711 USA
| | - Donald K Price
- Department of Biology University of Hawai'i Hilo Hilo HI USA.,Tropical Conservation Biology and Environmental Science Graduate Program University of Hawai'i Hilo Hilo HI USA.,Present address: School of Life Sciences University of Nevada, Las Vegas 4505 S Maryland Pkwy Las Vegas NV 89154 USA
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Souissi A, Gagnaire PA, Bonhomme F, Bahri-Sfar L. Introgressive hybridization and morphological transgression in the contact zone between two Mediterranean Solea species. Ecol Evol 2017; 7:1394-1402. [PMID: 28261451 PMCID: PMC5330901 DOI: 10.1002/ece3.2533] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 09/04/2016] [Accepted: 09/13/2016] [Indexed: 11/12/2022] Open
Abstract
Hybrid zones provide natural experiments where new combinations of genotypes and phenotypes are produced. Studying the reshuffling of genotypes and remodeling of phenotypes in these zones is of particular interest to document the building of reproductive isolation and the possible emergence of transgressive phenotypes that can be a source of evolutionary novelties. Here, we specifically investigate the morphological variation patterns associated with introgressive hybridization between two species of sole, Solea senegalensis and Solea aegyptiaca. The relationship between genetic composition at nuclear loci and individual body shape variation was studied in four populations sampled across the hybrid zone located in northern Tunisia. A strong correlation between genetic and phenotypic variation was observed among all individuals but not within populations, including the two most admixed ones. Morphological convergence between parental species was observed close to the contact zone. Nevertheless, the samples taken closest to the hybrid zone also displayed deviant segregation of genotypes and phenotypes, as well as transgressive phenotypes. In these samples, deviant body shape variation could be partly attributed to a reduced condition index, and the distorted genetic composition was most likely due to missing allelic combinations. These results were interpreted as an indication of hybrid breakdown, which likely contributes to postmating reproductive isolation between the two species.
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Affiliation(s)
- Ahmed Souissi
- Université de Tunis El Manar Faculté des Sciences de Tunis UR 11ES08 Biologie integrative et écologie évolutive et fonctionnelle des milieu aquatiques, 2092 Tunis Tunisie; Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France
| | - Pierre-Alexandre Gagnaire
- Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France
| | - François Bonhomme
- Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France
| | - Lilia Bahri-Sfar
- Université de Tunis El Manar Faculté des Sciences de Tunis UR 11ES08 Biologie integrative et écologie évolutive et fonctionnelle des milieu aquatiques, 2092 Tunis Tunisie
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48
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Romero Navarro JA, Willcox M, Burgueño J, Romay C, Swarts K, Trachsel S, Preciado E, Terron A, Delgado HV, Vidal V, Ortega A, Banda AE, Montiel NOG, Ortiz-monasterio I, Vicente FS, Espinoza AG, Atlin G, Wenzl P, Hearne S, Buckler ES. A study of allelic diversity underlying flowering-time adaptation in maize landraces. Nat Genet 2017; 49:476-80. [DOI: 10.1038/ng.3784] [Citation(s) in RCA: 188] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 01/10/2017] [Indexed: 12/15/2022]
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49
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Holliday JA, Aitken SN, Cooke JEK, Fady B, González-Martínez SC, Heuertz M, Jaramillo-Correa JP, Lexer C, Staton M, Whetten RW, Plomion C. Advances in ecological genomics in forest trees and applications to genetic resources conservation and breeding. Mol Ecol 2017; 26:706-717. [PMID: 27997049 DOI: 10.1111/mec.13963] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/07/2016] [Accepted: 12/14/2016] [Indexed: 12/25/2022]
Abstract
Forest trees are an unparalleled group of organisms in their combined ecological, economic and societal importance. With widespread distributions, predominantly random mating systems and large population sizes, most tree species harbour extensive genetic variation both within and among populations. At the same time, demographic processes associated with Pleistocene climate oscillations and land-use change have affected contemporary range-wide diversity and may impinge on the potential for future adaptation. Understanding how these adaptive and neutral processes have shaped the genomes of trees species is therefore central to their management and conservation. As for many other taxa, the advent of high-throughput sequencing methods is expected to yield an understanding of the interplay between the genome and environment at a level of detail and depth not possible only a few years ago. An international conference entitled 'Genomics and Forest Tree Genetics' was held in May 2016, in Arcachon (France), and brought together forest geneticists with a wide range of research interests to disseminate recent efforts that leverage contemporary genomic tools to probe the population, quantitative and evolutionary genomics of trees. An important goal of the conference was to discuss how such data can be applied to both genome-enabled breeding and the conservation of forest genetic resources under land use and climate change. Here, we report discoveries presented at the meeting and discuss how the ecological genomic toolkit can be used to address both basic and applied questions in tree biology.
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Affiliation(s)
- Jason A Holliday
- Department of Forest Resources and Environmental Conservation, Virginia Tech, 304 Cheatham Hall, Blacksburg, VA 24061, USA
| | - Sally N Aitken
- Department of Forest and Conservation Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC V6T1Z4, Canada
| | - Janice E K Cooke
- Department of Biological Sciences, University of Alberta, 5-108 Centennial Centre for Interdisciplinary Science, Edmonton, AB T6G2E9, Canada
| | - Bruno Fady
- Mediterranean Forest Ecology (URFM), Institut National de la Recherche Agronomique (INRA), Domaine St Paul, Site Agroparc, 84914 Avignon, France
| | | | - Myriam Heuertz
- BIOGECO, INRA, Universite de Bordeaux, 69 Route d'Arcachon, 33612 Cestas, France
| | - Juan-Pablo Jaramillo-Correa
- Institute of Ecology, Universidad Nacional Autonoma de Mexico (UNAM) Circuito Exterior s/n, Apartado Postal 70-275, 04510 Ciudad de México, Mexico City, Mexico
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna Faculty of Life SciencesRennweg 14, Room 217, A-1030, Vienna, Austria
| | - Margaret Staton
- Department of Entomology and Plant Pathology, University of Tennessee, 370 Plant Biotechnology Building, 2505 EJ Chapman Drive, Knoxville, TN 37996, USA
| | - Ross W Whetten
- Department of Forestry and Environmental Resources, North Carolina State University Jordan Hall Addition 5231, Raleigh, NC 27695, USA
| | - Christophe Plomion
- BIOGECO, INRA, Universite de Bordeaux, 69 Route d'Arcachon, 33612 Cestas, France
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50
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Nosil P, Feder JL, Flaxman SM, Gompert Z. Tipping points in the dynamics of speciation. Nat Ecol Evol 2017; 1. [DOI: 10.1038/s41559-016-0001] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 10/11/2016] [Indexed: 01/06/2023]
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