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Feller AF, Peichel CL, Seehausen O. Testing for a role of postzygotic incompatibilities in rapidly speciated Lake Victoria cichlids. Evolution 2024; 78:652-664. [PMID: 38288653 DOI: 10.1093/evolut/qpae007] [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: 09/29/2023] [Revised: 12/22/2023] [Accepted: 01/29/2024] [Indexed: 03/27/2024]
Abstract
Intrinsic postzygotic hybrid incompatibilities are usually due to negative epistatic interactions between alleles from different parental genomes. While such incompatibilities are thought to be uncommon in speciation with gene flow, they may be important if such speciation results from a hybrid population. Here we aimed to test this idea in the endemic cichlid fishes of Lake Victoria. Hundreds of species have evolved within the lake in <15k years from hybrid progenitors. While the importance of prezygotic barriers to gene flow is well established in this system, the possible relevance of postzygotic genetic incompatibilities is unknown. We inferred the presence of negative epistatic interactions from systematic patterns of genotype ratio distortions in experimental crosses and wild samples. We then compared the positions of putative incompatibility loci to regions of high genetic differentiation between sympatric sister species and between members of clades that may have arisen in the early history of this radiation, and further determined if the loci showed fixed differences between the closest living relatives of the lineages ancestral to the hybrid progenitors. Overall, we find little evidence for a major role of intrinsic postzygotic incompatibilities in the Lake Victoria radiation. However, we find putative incompatibility loci significantly more often coinciding with islands of genetic differentiation between species that separated early in the radiation than between the younger sister species, consistent with the hypothesis that such variants segregated in the hybrid swarm and were sorted between species in the early speciation events.
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Affiliation(s)
- Anna F Feller
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, Eawag Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
- Arnold Arboretum of Harvard University, Boston, MA, United States
| | - Catherine L Peichel
- Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Ole Seehausen
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, Eawag Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
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Merrill RM, Arenas-Castro H, Feller AF, Harenčár J, Rossi M, Streisfeld MA, Kay KM. Genetics and the Evolution of Prezygotic Isolation. Cold Spring Harb Perspect Biol 2024; 16:a041439. [PMID: 37848246 PMCID: PMC10835618 DOI: 10.1101/cshperspect.a041439] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 10/19/2023]
Abstract
The significance of prezygotic isolation for speciation has been recognized at least since the Modern Synthesis. However, fundamental questions remain. For example, how are genetic associations between traits that contribute to prezygotic isolation maintained? What is the source of genetic variation underlying the evolution of these traits? And how do prezygotic barriers affect patterns of gene flow? We address these questions by reviewing genetic features shared across plants and animals that influence prezygotic isolation. Emerging technologies increasingly enable the identification and functional characterization of the genes involved, allowing us to test established theoretical expectations. Embedding these genes in their developmental context will allow further predictions about what constrains the evolution of prezygotic isolation. Ongoing improvements in statistical and computational tools will reveal how pre- and postzygotic isolation may differ in how they influence gene flow across the genome. Finally, we highlight opportunities for progress by combining theory with appropriate data.
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Affiliation(s)
- Richard M Merrill
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Henry Arenas-Castro
- School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Anna F Feller
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Arnold Arboretum of Harvard University, Boston, Massachusetts 02131, USA
| | - Julia Harenčár
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, California 95060, USA
| | - Matteo Rossi
- Faculty of Biology, Division of Evolutionary Biology, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Matthew A Streisfeld
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon 97403-5289, USA
| | - Kathleen M Kay
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, California 95060, USA
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Feller AF, Seehausen O. Genetic architecture of adaptive radiation across two trophic levels. Proc Biol Sci 2022; 289:20220377. [PMID: 35506225 PMCID: PMC9065965 DOI: 10.1098/rspb.2022.0377] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Evolution of trophic diversity is a hallmark of adaptive radiation. Yet, transitions between carnivory and herbivory are rare in young adaptive radiations. Haplochromine cichlid fish of the African Great Lakes are exceptional in this regard. Lake Victoria was colonized by an insectivorous generalist and in less than 20 000 years, several clades of specialized herbivores evolved. Carnivorous versus herbivorous lifestyles in cichlids require many different adaptations in functional morphology, physiology and behaviour. Ecological transitions in either direction thus require many traits to change in a concerted fashion, which could be facilitated if genomic regions underlying these traits were physically linked or pleiotropic. However, linkage/pleiotropy could also constrain evolvability. To investigate components of the genetic architecture of a suite of traits that distinguish invertivores from algae scrapers, we performed quantitative trait locus (QTL) mapping using a second-generation hybrid cross. While we found indications of linkage/pleiotropy within trait complexes, QTLs for distinct traits were distributed across several unlinked genomic regions. Thus, a mixture of independently segregating variation and some pleiotropy may underpin the rapid trophic transitions. We argue that the emergence and maintenance of associations between the different genomic regions underpinning co-adapted traits that evolved and persist against some gene flow required reproductive isolation.
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Affiliation(s)
- Anna F. Feller
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland,Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Ole Seehausen
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland,Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
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Feller AF, Ogi V, Seehausen O, Meier JI. Identification of a novel sex determining chromosome in cichlid fishes that acts as XY or ZW in different lineages. Hydrobiologia 2021; 848:3727-3745. [PMID: 34720170 PMCID: PMC8550731 DOI: 10.1007/s10750-021-04560-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 02/02/2021] [Accepted: 02/23/2021] [Indexed: 05/02/2023]
Abstract
UNLABELLED Sex determination systems are highly conserved among most vertebrates with genetic sex determination, but can be variable and evolve rapidly in some. Here, we study sex determination in a clade with exceptionally high sex chromosome turnover rates. We identify the sex determining chromosomes in three interspecific crosses of haplochromine cichlid fishes from Lakes Victoria and Malawi. We find evidence for different sex determiners in each cross. In the Malawi cross and one Victoria cross the same chromosome is sex-linked but while females are the heterogametic sex in the Malawi species, males are the heterogametic sex in the Victoria species. This chromosome has not previously been reported to be sex determining in cichlids, increasing the number of different chromosomes shown to be sex determining in cichlids to 12. All Lake Victoria species of our crosses are less than 15,000 years divergent, and we identified different sex determiners among them. Our study provides further evidence for the diversity and evolutionary flexibility of sex determination in cichlids, factors which might contribute to their rapid adaptive radiations. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10750-021-04560-7.
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Affiliation(s)
- Anna F. Feller
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Vera Ogi
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Ole Seehausen
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
| | - Joana I. Meier
- Division of Aquatic Ecology & Evolution, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry (CEEB), Eawag Swiss Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6047 Kastanienbaum, Switzerland
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ UK
- St John’s College, University of Cambridge, St John’s Street, Cambridge, CB2 1TP UK
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Feller AF, Selz OM, McGee MD, Meier JI, Mwaiko S, Seehausen O. Rapid generation of ecologically relevant behavioral novelty in experimental cichlid hybrids. Ecol Evol 2020; 10:7445-7462. [PMID: 32760540 PMCID: PMC7391563 DOI: 10.1002/ece3.6471] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 01/28/2020] [Revised: 05/15/2020] [Accepted: 05/16/2020] [Indexed: 01/25/2023] Open
Abstract
The East African cichlid radiations are characterized by repeated and rapid diversification into many distinct species with different ecological specializations and by a history of hybridization events between nonsister species. Such hybridization might provide important fuel for adaptive radiation. Interspecific hybrids can have extreme trait values or novel trait combinations and such transgressive phenotypes may allow some hybrids to explore ecological niches neither of the parental species could tap into. Here, we investigate the potential of second-generation (F2) hybrids between two generalist cichlid species from Lake Malawi to exploit a resource neither parental species is specialized on: feeding by sifting sand. Some of the F2 hybrids phenotypically resembled fish of species that are specialized on sand sifting. We combined experimental behavioral and morphometric approaches to test whether the F2 hybrids are transgressive in both morphology and behavior related to sand sifting. We then performed a quantitative trait loci (QTL) analysis using RADseq markers to investigate the genetic architecture of morphological and behavioral traits. We show that transgression is present in several morphological traits, that novel trait combinations occur, and we observe transgressive trait values in sand sifting behavior in some of the F2 hybrids. Moreover, we find QTLs for morphology and for sand sifting behavior, suggesting the existence of some loci with moderate to large effects. We demonstrate that hybridization has the potential to rapidly generate novel and ecologically relevant phenotypes that may be suited to a niche neither of the parental species occupies. Interspecific hybridization may thereby contribute to the rapid generation of ecological diversity in cichlid radiations.
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Affiliation(s)
- Anna F. Feller
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Oliver M. Selz
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Matthew D. McGee
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
- School of Biological SciencesMonash UniversityClaytonVic.Australia
| | - Joana I. Meier
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
- Department of ZoologyUniversity of CambridgeCambridgeUK
- St John’s CollegeUniversity of CambridgeCambridgeUK
| | - Salome Mwaiko
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
| | - Ole Seehausen
- Division of Aquatic Ecology and EvolutionInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
- Department of Fish Ecology and EvolutionCentre of Ecology, Evolution and BiogeochemistryEAWAG Swiss Federal Institute of Aquatic Science and TechnologyKastanienbaumSwitzerland
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Feller AF, Haesler MP, Peichel CL, Seehausen O. Genetic architecture of a key reproductive isolation trait differs between sympatric and non-sympatric sister species of Lake Victoria cichlids. Proc Biol Sci 2020; 287:20200270. [PMID: 32259470 PMCID: PMC7209058 DOI: 10.1098/rspb.2020.0270] [Citation(s) in RCA: 8] [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] [Indexed: 01/06/2023] Open
Abstract
One hallmark of the East African cichlid radiations is the rapid evolution of reproductive isolation that is robust to full sympatry of many closely related species. Theory predicts that species persistence and speciation in sympatry with gene flow are facilitated if loci of large effect or physical linkage (or pleiotropy) underlie traits involved in reproductive isolation. Here, we investigate the genetic architecture of a key trait involved in behavioural isolation, male nuptial coloration, by crossing two sister species pairs of Lake Victoria cichlids of the genus Pundamilia and mapping nuptial coloration in the F2 hybrids. One is a young sympatric species pair, representative of an axis of colour motif differentiation, red-dorsum versus blue, that is highly recurrent in closely related sympatric species. The other is a species pair representative of colour motifs, red-chest versus blue, that are common in allopatric but uncommon in sympatric closely related species. We find significant quantitative trait loci (QTLs) with moderate to large effects (some overlapping) for red and yellow in the sympatric red-dorsum × blue cross, whereas we find no significant QTLs in the non-sympatric red-chest × blue cross. These findings are consistent with theory predicting that large effect loci or linkage/pleiotropy underlying mating trait differentiation could facilitate speciation and species persistence with gene flow in sympatry.
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Affiliation(s)
- Anna F Feller
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland.,Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
| | - Marcel P Haesler
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland.,Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
| | - Catherine L Peichel
- Division of Evolutionary Ecology, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Ole Seehausen
- Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland.,Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
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Abstract
A clear understanding of infant mental health will significantly assist a clinician's ability to provide high-quality paediatric care for children and their families, given the new understanding of its role in overall development. The present commentary describes the mental health needs of children <3 years of age and provides practical suggestions for the office setting.
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Affiliation(s)
- J Clinton
- Department of Pediatrics, McMaster University, Hamilton, Ontario
| | - A F Feller
- Department of Pediatrics, McMaster University, Hamilton, Ontario
| | - R C Williams
- Department of Pediatrics, McMaster University, Hamilton, Ontario
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