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Mrnjavac A, Khudiakova KA, Barton NH, Vicoso B. Slower-X: reduced efficiency of selection in the early stages of X chromosome evolution. Evol Lett 2023; 7:4-12. [PMID: 37065438 PMCID: PMC10091493 DOI: 10.1093/evlett/qrac004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/08/2022] [Accepted: 12/17/2022] [Indexed: 02/04/2023] Open
Abstract
Abstract
Differentiated X chromosomes are expected to have higher rates of adaptive divergence than autosomes, if new beneficial mutations are recessive (the “faster-X effect”), largely because these mutations are immediately exposed to selection in males. The evolution of X chromosomes after they stop recombining in males, but before they become hemizygous, has not been well explored theoretically. We use the diffusion approximation to infer substitution rates of beneficial and deleterious mutations under such a scenario. Our results show that selection is less efficient on diploid X loci than on autosomal and hemizygous X loci under a wide range of parameters. This “slower-X” effect is stronger for genes affecting primarily (or only) male fitness, and for sexually antagonistic genes. These unusual dynamics suggest that some of the peculiar features of X chromosomes, such as the differential accumulation of genes with sex-specific functions, may start arising earlier than previously appreciated.
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Affiliation(s)
- Andrea Mrnjavac
- Institute of Science and Technology Austria , Am Campus 1, 3400 Klosterneuburg , Austria
| | - Ksenia A Khudiakova
- Institute of Science and Technology Austria , Am Campus 1, 3400 Klosterneuburg , Austria
| | - Nicholas H Barton
- Institute of Science and Technology Austria , Am Campus 1, 3400 Klosterneuburg , Austria
| | - Beatriz Vicoso
- Institute of Science and Technology Austria , Am Campus 1, 3400 Klosterneuburg , Austria
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Pettie N, Llopart A, Comeron JM. Meiotic, genomic and evolutionary properties of crossover distribution in Drosophila yakuba. PLoS Genet 2022; 18:e1010087. [PMID: 35320272 PMCID: PMC8979470 DOI: 10.1371/journal.pgen.1010087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 04/04/2022] [Accepted: 02/09/2022] [Indexed: 12/14/2022] Open
Abstract
The number and location of crossovers across genomes are highly regulated during meiosis, yet the key components controlling them are fast evolving, hindering our understanding of the mechanistic causes and evolutionary consequences of changes in crossover rates. Drosophila melanogaster has been a model species to study meiosis for more than a century, with an available high-resolution crossover map that is, nonetheless, missing for closely related species, thus preventing evolutionary context. Here, we applied a novel and highly efficient approach to generate whole-genome high-resolution crossover maps in D. yakuba to tackle multiple questions that benefit from being addressed collectively within an appropriate phylogenetic framework, in our case the D. melanogaster species subgroup. The genotyping of more than 1,600 individual meiotic events allowed us to identify several key distinct properties relative to D. melanogaster. We show that D. yakuba, in addition to higher crossover rates than D. melanogaster, has a stronger centromere effect and crossover assurance than any Drosophila species analyzed to date. We also report the presence of an active crossover-associated meiotic drive mechanism for the X chromosome that results in the preferential inclusion in oocytes of chromatids with crossovers. Our evolutionary and genomic analyses suggest that the genome-wide landscape of crossover rates in D. yakuba has been fairly stable and captures a significant signal of the ancestral crossover landscape for the whole D. melanogaster subgroup, even informative for the D. melanogaster lineage. Contemporary crossover rates in D. melanogaster, on the other hand, do not recapitulate ancestral crossovers landscapes. As a result, the temporal stability of crossover landscapes observed in D. yakuba makes this species an ideal system for applying population genetic models of selection and linkage, given that these models assume temporal constancy in linkage effects. Our studies emphasize the importance of generating multiple high-resolution crossover rate maps within a coherent phylogenetic context to broaden our understanding of crossover control during meiosis and to improve studies on the evolutionary consequences of variable crossover rates across genomes and time.
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Affiliation(s)
- Nikale Pettie
- Interdisciplinary Program in Genetics, University of Iowa, Iowa City, Iowa, United States of America
| | - Ana Llopart
- Interdisciplinary Program in Genetics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Josep M. Comeron
- Interdisciplinary Program in Genetics, University of Iowa, Iowa City, Iowa, United States of America
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Go AC, Civetta A. Divergence of X-linked trans regulatory proteins and the misexpression of gene targets in sterile Drosophila pseudoobscura hybrids. BMC Genomics 2022; 23:30. [PMID: 34991488 PMCID: PMC8740060 DOI: 10.1186/s12864-021-08267-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/20/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The genetic basis of hybrid incompatibilities is characterized by pervasive cases of gene interactions. Sex chromosomes play a major role in speciation and X-linked hybrid male sterility (HMS) genes have been identified. Interestingly, some of these genes code for proteins with DNA binding domains, suggesting a capability to act as trans-regulatory elements and disturb the expression of a large number of gene targets. To understand how interactions between trans- and cis-regulatory elements contribute to speciation, we aimed to map putative X-linked trans-regulatory elements and to identify gene targets with disrupted gene expression in sterile hybrids between the subspecies Drosophila pseudoobscura pseudoobscura and D. p. bogotana. RESULTS We find six putative trans-regulatory proteins within previously mapped X chromosome HMS loci with sequence changes that differentiate the two subspecies. Among them, the previously characterized HMS gene Overdrive (Ovd) had the largest number of amino acid changes between subspecies, with some substitutions localized within the protein's DNA binding domain. Using an introgression approach, we detected transcriptional responses associated with a sterility/fertility Ovd allele swap. We found a network of 52 targets of Ovd and identified cis-regulatory effects among target genes with disrupted expression in sterile hybrids. However, a combined analysis of polymorphism and divergence in non-coding sequences immediately upstream of target genes found no evidence of changes in candidate regulatory proximal cis-elements. Finally, peptidases were over-represented among target genes. CONCLUSIONS We provide evidence of divergence between subspecies within the DNA binding domain of the HMS protein Ovd and identify trans effects on the expression of 52 gene targets. Our results identify a network of trans-cis interactions with possible effects on HMS. This network provides molecular evidence of gene × gene incompatibilities as contributors to hybrid dysfunction.
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Affiliation(s)
- Alwyn C Go
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada.
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Lichilín N, El Taher A, Böhne A. Sex-biased gene expression and recent sex chromosome turnover. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200107. [PMID: 34304591 PMCID: PMC8310714 DOI: 10.1098/rstb.2020.0107] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2020] [Indexed: 12/13/2022] Open
Abstract
Cichlids are well known for their propensity to radiate generating arrays of morphologically and ecologically diverse species in short evolutionary time. Following this rapid evolutionary pace, cichlids show high rates of sex chromosome turnover. We here studied the evolution of sex-biased gene (SBG) expression in 14 recently diverged taxa of the Lake Tanganyika Tropheini cichlids, which show different XY sex chromosomes. Across species, sex chromosome sequence divergence predates divergence in expression between the sexes. Only one sex chromosome, the oldest, showed signs of demasculinization in gene expression and potentially contribution to the resolution of sexual conflict. SBGs in general showed high rates of turnovers and evolved mostly under drift. Sexual selection did not shape the rapid evolutionary changes of SBGs. Male-biased genes evolved faster than female-biased genes, which seem to be under more phylogenetic constraint. We found a relationship between the degree of sex bias and sequence evolution driven by sequence differences among the sexes. Consistent with other species, strong sex bias towards sex-limited expression contributes to resolving sexual conflict in cichlids. This article is part of the theme issue 'Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)'.
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Affiliation(s)
- Nicolás Lichilín
- Zoological Institute, Department of Environmental Sciences, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Athimed El Taher
- Zoological Institute, Department of Environmental Sciences, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Astrid Böhne
- Zoological Institute, Department of Environmental Sciences, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
- Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Adenauerallee 160, 53113 Bonn, Germany
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Jayaswal V, Ndo C, Ma HC, Clifton BD, Pombi M, Cabrera K, Couhet A, Mouline K, Diabaté A, Dabiré R, Ayala D, Ranz JM. Intraspecific Transcriptome Variation and Sex-Biased Expression in Anopheles arabiensis. Genome Biol Evol 2021; 13:6357708. [PMID: 34432020 PMCID: PMC8449828 DOI: 10.1093/gbe/evab199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2021] [Indexed: 01/17/2023] Open
Abstract
The magnitude and functional patterns of intraspecific transcriptional variation in the anophelines, including those of sex-biased genes underlying sex-specific traits relevant for malaria transmission, remain understudied. As a result, how changes in expression levels drive adaptation in these species is poorly understood. We sequenced the female, male, and larval transcriptomes of three populations of Anopheles arabiensis from Burkina Faso. One-third of the genes were differentially expressed between populations, often involving insecticide resistance-related genes in a sample type-specific manner, and with the females showing the largest number of differentially expressed genes. At the genomic level, the X chromosome appears depleted of differentially expressed genes compared with the autosomes, chromosomes harboring inversions do not exhibit evidence for enrichment of such genes, and genes that are top contributors to functional enrichment patterns of population differentiation tend to be clustered in the genome. Further, the magnitude of variation for the sex expression ratio across populations did not substantially differ between male- and female-biased genes, except for some populations in which male-limited expressed genes showed more variation than their female counterparts. In fact, female-biased genes exhibited a larger level of interpopulation variation than male-biased genes, both when assayed in males and females. Beyond uncovering the extensive adaptive potential of transcriptional variation in An. Arabiensis, our findings suggest that the evolutionary rate of changes in expression levels on the X chromosome exceeds that on the autosomes, while pointing to female-biased genes as the most variable component of the An. Arabiensis transcriptome.
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Affiliation(s)
- Vivek Jayaswal
- School of Mathematics and Statistics, The University of Sydney, Sydney, NSW, Australia
| | - Cyrille Ndo
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Hsiu-Ching Ma
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, USA
| | - Bryan D Clifton
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, USA
| | - Marco Pombi
- Dipartimento di Sanità Pubblica e Malattie Infettive, University of Rome "Sapienza", Rome, Italy
| | - Kevin Cabrera
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, USA
| | - Anna Couhet
- Unité Mixte de Recherche Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, University of Montpellier, CNRS, Montpellier, IRD, France
| | - Karine Mouline
- Unité Mixte de Recherche Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, University of Montpellier, CNRS, Montpellier, IRD, France
| | - Abdoulaye Diabaté
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Roch Dabiré
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Diego Ayala
- Unité Mixte de Recherche Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, University of Montpellier, CNRS, Montpellier, IRD, France
| | - José M Ranz
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, California, USA
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Rieseberg L, Geraldes A, Belkin SE, Chambers KE, Kane N. Editorial 2019. Mol Ecol 2019; 28:1-28. [DOI: 10.1111/mec.14976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Payseur BA, Presgraves DC, Filatov DA. Introduction: Sex chromosomes and speciation. Mol Ecol 2018; 27:3745-3748. [PMID: 30086196 DOI: 10.1111/mec.14828] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Bret A Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin
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Support for the Dominance Theory in Drosophila Transcriptomes. Genetics 2018; 210:703-718. [PMID: 30131345 PMCID: PMC6216581 DOI: 10.1534/genetics.118.301229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/10/2018] [Indexed: 12/14/2022] Open
Abstract
Interactions among divergent elements of transcriptional networks from different species can lead to misexpression in hybrids through regulatory incompatibilities, some with the potential to generate sterility. While the possible contribution of faster-male evolution to this misexpression has been explored, the role of the hemizygous X chromosome (i.e., the dominance theory for transcriptomes) remains yet to be determined. Here, we study genome-wide patterns of gene expression in females and males of Drosophila yakuba, Drosophila santomea and their hybrids. We used attached-X stocks to specifically test the dominance theory, and we uncovered a significant contribution of recessive alleles on the X chromosome to hybrid misexpression. Our analyses also suggest a contribution of weakly deleterious regulatory mutations to gene expression divergence in genes with sex-biased expression, but only in the sex toward which the expression is biased (e.g., genes with female-biased expression when analyzed in females). In the opposite sex, we found stronger selective constraints on gene expression divergence. Although genes with a high degree of male-biased expression show a clear signal of faster-X evolution of gene expression, we also detected slower-X evolution in other gene classes (e.g., female-biased genes). This slower-X effect is mediated by significant decreases in cis- and trans-regulatory divergence. The distinct behavior of X-linked genes with a high degree of male-biased expression is consistent with these genes experiencing a higher incidence of positively selected regulatory mutations than their autosomal counterparts.
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