1
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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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2
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Kawamura W, Tani R, Yahagi H, Kamio S, Morita T, Takeuchi Y, Yazawa R, Yoshizaki G. Suitability of hybrid mackerel (Scomber australasicus × S. japonicus) with germ cell-less sterile gonads as a recipient for transplantation of bluefin tuna germ cells. Gen Comp Endocrinol 2020; 295:113525. [PMID: 32502497 DOI: 10.1016/j.ygcen.2020.113525] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/25/2020] [Accepted: 05/30/2020] [Indexed: 01/11/2023]
Abstract
We aim to establish a small-bodied surrogate broodstock, such as mackerel, which produces functional bluefin tuna gametes by spermatogonial transplantation. When reproductively fertile fish are used as recipients, endogenous gametogenesis outcompetes donor-derived gametogenesis, and recipient fish predominantly produce their gametes. In this study, we assessed fertility of hybrid mackerel, Scomber australasicus × S. japonicus, and its suitability as a recipient for transplantation of bluefin tuna germ cells. Hybrid mackerel were produced by artificially inseminating S. australasicus eggs with S. japonicus spermatozoa. Cellular DNA content and PCR analyses revealed that F1 offspring were diploid carrying both paternal and maternal genomes. Surprisingly, histological observations found no germ cells in hybrid mackerel gonads at 120 days post-hatch (dph), although they were present in the gonad of 30- and 60-dph hybrid mackerel. The frequency of germ cell-less fish was 100% at 120-dph, 63.1% at 1-year-old, and 81.8% at 2-year-old. We also confirmed a lack of expression of germ cell marker (DEAD-box helicase 4, ddx4) in the germ cell-less gonads of hybrid mackerel. By contrast, expression of Sertoli cell marker (gonadal soma-derived growth factor, gsdf) and of Leydig cell marker (steroid 11-beta-hydroxlase, cyp11b1) were clearly detected in hybrid mackerel gonads. Together these results showed that most of the hybrid gonads were germ cell-less sterile, but still possessed supporting cells and steroidogenic cells, both of which are indispensable for nursing donor-derived germ cells. To determine whether hybrid gonads could attract and incorporate donor bluefin tuna germ cells, testicular cells labeled with PKH26 fluorescent dye were intraperitoneally transplanted. Fluorescence observation of hybrid recipients at 14 days post-transplantation revealed that donor cells had been incorporated into the recipient's gonads. This suggests that hybrid mackerel show significant promise for use as a recipient to produce bluefin tuna gametes.
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Affiliation(s)
- Wataru Kawamura
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
| | - Reoto Tani
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
| | - Hana Yahagi
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
| | - Shigeharu Kamio
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan
| | - Tetsuro Morita
- Oita Marine Biological Technology Center, Nippon Suisan Kaisha, Ltd., 508-8, Ariakrura Turumi, Saiki-shi, Oita 876-1204, Japan
| | - Yutaka Takeuchi
- Noto Center for Fisheries Science and Technology, Faculty of Biological Science and Technology, Kanazawa University, 11-4-1 Otsusaka, Noto-cho, Ishikawa 927-0552, Japan
| | - Ryosuke Yazawa
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
| | - Goro Yoshizaki
- Department of Marine Biosciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
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3
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Abstract
It has long been acknowledged that changes in the regulation of gene expression may account for major organismal differences. However, we still do not fully understand how changes in gene expression evolve and how do such changes influence organisms' differences. We are even less aware of the impact such changes might have in restricting gene flow between species. Here, we focus on studies of gene expression and speciation in the Drosophila model. We review studies that have identified gene interactions in post-mating reproductive isolation and speciation, particularly those that modulate male gene expression. We also address studies that have experimentally manipulated changes in gene expression to test their effect in post-mating reproductive isolation. We highlight the need for a more in-depth analysis of the role of selection causing disrupted gene expression of such candidate genes in sterile/inviable hybrids. Moreover, we discuss the relevance to incorporate more routinely assays that simultaneously evaluate the potential effects of environmental factors and genetic background in modulating plastic responses in male genes and their potential role in speciation.
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Affiliation(s)
- Bahar Patlar
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada.,Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
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4
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Evaluation of Drosophila chromosomal segments proposed by means of simulations of possessing hybrid sterility genes from reproductive isolation. J Genet 2020. [DOI: 10.1007/s12041-020-01215-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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5
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Pischedda A, Shahandeh MP, Turner TL. The Loci of Behavioral Evolution: Evidence That Fas2 and tilB Underlie Differences in Pupation Site Choice Behavior between Drosophila melanogaster and D. simulans. Mol Biol Evol 2020; 37:864-880. [PMID: 31774527 DOI: 10.1093/molbev/msz274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The behaviors of closely related species can be remarkably different, and these differences have important ecological and evolutionary consequences. Although the recent boom in genotype-phenotype studies has led to a greater understanding of the genetic architecture and evolution of a variety of traits, studies identifying the genetic basis of behaviors are, comparatively, still lacking. This is likely because they are complex and environmentally sensitive phenotypes, making them difficult to measure reliably for association studies. The Drosophila species complex holds promise for addressing these challenges, as the behaviors of closely related species can be readily assayed in a common environment. Here, we investigate the genetic basis of an evolved behavioral difference, pupation site choice, between Drosophila melanogaster and D. simulans. In this study, we demonstrate a significant contribution of the X chromosome to the difference in pupation site choice behavior between these species. Using a panel of X-chromosome deficiencies, we screened the majority of the X chromosome for causal loci and identified two regions associated with this X-effect. We then collect gene disruption and RNAi data supporting a single gene that affects pupation behavior within each region: Fas2 and tilB. Finally, we show that differences in tilB expression correlate with the differences in pupation site choice behavior between species. This evidence associating two genes with differences in a complex, environmentally sensitive behavior represents the first step toward a functional and evolutionary understanding of this behavioral divergence.
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Affiliation(s)
- Alison Pischedda
- Department of Biology, Barnard College, Columbia University, New York, NY
| | - Michael P Shahandeh
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA
| | - Thomas L Turner
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA
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6
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Go A, Alhazmi D, Civetta A. Altered expression of cell adhesion genes and hybrid male sterility between subspecies ofDrosophila pseudoobscura. Genome 2019; 62:657-663. [DOI: 10.1139/gen-2019-0066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Drosophila pseudoobscura pseudoobscura and Drosophila pseudoobscura bogotana are two closely related subspecies with incomplete reproductive isolation. A genome-wide comparison of expression in hybrids relative to parental subspecies has been previously used to identify genes with significant changes in expression uniquely associated with the sterile condition. The misexpression (i.e., gene expression beyond levels found in parentals) of such genes could be directly linked to the onset of sterility or could alternatively be caused by incompatibilities in a hybrid genome without a direct link to sterility. Cell adhesion was previously found to be one of the largest gene ontologies with changes in expression linked to sterility. Here we used gene expression assays in fertile backcross male progeny, along with introgression progeny in which we swap a major hybrid male sterility (HMS) allele, to generate fertile and sterile males genotypically similar to F1sterile hybrids. We identify a cell adhesion gene (GA10921) whose change in expression is directly linked to sterility and modulated by a previously characterized HMS protein. GA10921 adds to our rather limited knowledge of changes in gene expression associated with HMS, and to the identification of gene interacting partners linked to HMS.
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Affiliation(s)
- Alwyn Go
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Doaa Alhazmi
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
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7
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Testes Proteases Expression and Hybrid Male Sterility Between Subspecies of Drosophila pseudoobscura. G3-GENES GENOMES GENETICS 2019; 9:1065-1074. [PMID: 30723102 PMCID: PMC6469408 DOI: 10.1534/g3.119.300580] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hybrid male sterility (HMS) is a form of postmating postzygotic isolation among closely related species that can act as an effective barrier to gene flow. The Dobzhansky-Muller model provides a framework to explain how gene interactions can cause HMS between species. Genomics highlights the preponderance of non-coding DNA targets that could be involved in gene interactions resulting in gene expression changes and the establishment of isolating barriers. However, we have limited knowledge of changes in gene expression associated with HMS, gene interacting partners linked to HMS, and whether substitutions in DNA regulatory regions (cis) causes misexpression (i.e., expression of genes beyond levels found in parental species) of HMS genes in sterile hybrids. A previous transcriptome survey in a pair of D. pseudoobscura species found male reproductive tract (MRT) proteases as the largest class of genes misregulated in sterile hybrids. Here we assay gene expression in backcross (BC) and introgression (IG) progeny, along with site of expression within the MRT, to identify misexpression of proteases that might directly contribute to HMS. We find limited evidence of an accumulation of cis-regulatory changes upstream of such candidate HMS genes. The expression of four genes was differentially modulated by alleles of the previously characterized HMS gene Ovd.
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8
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Hybrid Sterility in Fish Caused by Mitotic Arrest of Primordial Germ Cells. Genetics 2018; 209:507-521. [PMID: 29610216 DOI: 10.1534/genetics.118.300777] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/23/2018] [Indexed: 11/18/2022] Open
Abstract
Sterility in hybrid animals is widely known to be due to a cytological mechanism of aberrant homologous chromosome pairing during meiosis in hybrid germ cells. In this study, the gametes of four marine fish species belonging to the Sciaenid family were artificially fertilized, and germ cell development was examined at the cellular and molecular levels. One of the intergeneric hybrids had gonads that were testis-like in structure, small in size, and lacked germ cells. Specification of primordial germ cells (PGCs) and their migration toward genital ridges occurred normally in hybrid embryos, but these PGCs did not proliferate in the hybrid gonads. By germ cell transplantation assay, we showed that the gonadal microenvironment in hybrid recipients produced functional donor-derived gametes, suggesting that the germ cell-less phenotype was caused by cell autonomous proliferative defects of hybrid PGCs. This is the first evidence of mitotic arrest of germ cells causing hybrid sterility in animals.
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9
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Matute DR, Gavin-Smyth J, Liu G. Variable post-zygotic isolation in Drosophila melanogaster/D. simulans
hybrids. J Evol Biol 2014; 27:1691-705. [DOI: 10.1111/jeb.12422] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 04/13/2014] [Accepted: 04/28/2014] [Indexed: 11/29/2022]
Affiliation(s)
- D. R. Matute
- Department of Human Genetics; The University of Chicago; Chicago IL USA
- The Chicago Fellows Program; The University of Chicago; Chicago IL USA
| | - J. Gavin-Smyth
- The Chicago Fellows Program; The University of Chicago; Chicago IL USA
- Department of Ecology and Evolution; The University of Chicago; Chicago IL USA
| | - G. Liu
- Department of Human Genetics; The University of Chicago; Chicago IL USA
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10
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Fraïsse C, Elderfield JAD, Welch JJ. The genetics of speciation: are complex incompatibilities easier to evolve? J Evol Biol 2014; 27:688-99. [PMID: 24581268 DOI: 10.1111/jeb.12339] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/11/2013] [Accepted: 01/04/2014] [Indexed: 01/22/2023]
Abstract
Reproductive isolation can evolve readily when genotypes containing incompatible alleles are connected by chains of fit intermediates. Experimental crosses show that such Dobzhansky-Muller incompatibilities (DMIs) are often complex (involving alleles at three or more loci) and asymmetrical (such that reciprocal introgressions have very different effects on fitness). One possible explanation is that asymmetrical and complex DMIs are 'easier to evolve', because they block fewer of the possible evolutionary paths between the parental genotypes. To assess this argument, we model evolutionary divergence in allopatry and calculate the delays to divergence caused by DMIs of different kinds. We find that the number of paths is sometimes, though not always, a reliable predictor of the time to divergence. In particular, we find limited support for the idea that symmetrical DMIs take longer to evolve, but this applies largely to two-locus symmetrical DMIs (which leave no path of fit intermediates). Symmetrical complex DMIs can also delay divergence, but only in a limited region of parameter space. In most other cases, the presence and form of DMIs have little influence on times to divergence, and so we argue that ease of evolution is unlikely to be important in explaining the experimental data.
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Affiliation(s)
- C Fraïsse
- Université Montpellier 2, Montpellier Cedex 5, France; Station Méditerranéenne de l'Environnement Littoral, CNRS, Institut des Sciences de l'Evolution (ISEM UMR 5554), Sete, France; Department of Genetics, University of Cambridge, Cambridge, UK
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11
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Laturney M, Moehring AJ. Fine-scale genetic analysis of species-specific female preference in Drosophila simulans. J Evol Biol 2012; 25:1718-31. [PMID: 22694106 DOI: 10.1111/j.1420-9101.2012.02550.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Behavioural differences are thought to be the first components to contribute to species isolation, yet the precise genetic basis of behavioural isolation remains poorly understood. Here, we used a combination of behaviour assays and genetic mapping to provide the first refined map locating candidate genes for interspecific female preference isolating Drosophila simulans from D. melanogaster. First, we tested whether two genes identified as affecting D. melanogaster female intraspecific mate choice also affect interspecific mate choice; neither of these genes was found to contribute to species-specific female preference. Next, we used deficiency mapping to locate genes on the right arm of the third chromosome for species-specific female preference and identified five small significant regions that contain candidate genes contributing to behavioural isolation. All five regions were located in areas that would have low interspecific recombination, which mirrors the results of other behavioural isolation studies that used quantitative trait locus (QTL) mapping, but without the potential concern of bias towards regions of low recombination that QTL mapping may have. As this model system may be refined to the individual gene level using the same methodology, this initial map we provide may potentially serve as a ready template for the identification and characterization of the first behavioural isolation genes.
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Affiliation(s)
- M Laturney
- Department of Biology, The University of Western Ontario, London, ON, Canada
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12
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Incompatibility between X chromosome factor and pericentric heterochromatic region causes lethality in hybrids between Drosophila melanogaster and its sibling species. Genetics 2012; 191:549-59. [PMID: 22446316 DOI: 10.1534/genetics.112.139683] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Dobzhansky-Muller model posits that postzygotic reproductive isolation results from the evolution of incompatible epistatic interactions between species: alleles that function in the genetic background of one species can cause sterility or lethality in the genetic background of another species. Progress in identifying and characterizing factors involved in postzygotic isolation in Drosophila has remained slow, mainly because Drosophila melanogaster, with all of its genetic tools, forms dead or sterile hybrids when crossed to its sister species, D. simulans, D. sechellia, and D. mauritiana. To circumvent this problem, we used chromosome deletions and duplications from D. melanogaster to map two hybrid incompatibility loci in F(1) hybrids with its sister species. We mapped a recessive factor to the pericentromeric heterochromatin of the X chromosome in D. simulans and D. mauritiana, which we call heterochromatin hybrid lethal (hhl), which causes lethality in F(1) hybrid females with D. melanogaster. As F(1) hybrid males hemizygous for a D. mauritiana (or D. simulans) X chromosome are viable, the lethality of deficiency hybrid females implies that a dominant incompatible partner locus exists on the D. melanogaster X. Using small segments of the D. melanogaster X chromosome duplicated onto the Y chromosome, we mapped a dominant factor that causes hybrid lethality to a small 24-gene region of the D. melanogaster X. We provide evidence suggesting that it interacts with hhl(mau). The location of hhl is consistent with the emerging theme that hybrid incompatibilities in Drosophila involve heterochromatic regions and factors that interact with the heterochromatin.
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13
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Chromatin evolution and molecular drive in speciation. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2011; 2012:301894. [PMID: 22191063 PMCID: PMC3235502 DOI: 10.1155/2012/301894] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 10/05/2011] [Indexed: 11/17/2022]
Abstract
Are there biological generalities that underlie hybrid sterility or inviability? Recently, around a dozen "speciation genes" have been identified mainly in Drosophila, and the biological functions of these genes are revealing molecular generalities. Major cases of hybrid sterility and inviability seem to result from chromatin evolution and molecular drive in speciation. Repetitive satellite DNAs within heterochromatin, especially at centromeres, evolve rapidly through molecular drive mechanisms (both meiotic and centromeric). Chromatin-binding proteins, therefore, must also evolve rapidly to maintain binding capability. As a result, chromatin binding proteins may not be able to interact with chromosomes from another species in a hybrid, causing hybrid sterility and inviability.
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14
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Araripe LO, Montenegro H, Lemos B, Hartl DL. Fine-scale genetic mapping of a hybrid sterility factor between Drosophila simulans and D. mauritiana: the varied and elusive functions of "speciation genes". BMC Evol Biol 2010; 10:385. [PMID: 21144061 PMCID: PMC3020225 DOI: 10.1186/1471-2148-10-385] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 12/14/2010] [Indexed: 11/10/2022] Open
Abstract
Background Hybrid male sterility (HMS) is a usual outcome of hybridization between closely related animal species. It arises because interactions between alleles that are functional within one species may be disrupted in hybrids. The identification of genes leading to hybrid sterility is of great interest for understanding the evolutionary process of speciation. In the current work we used marked P-element insertions as dominant markers to efficiently locate one genetic factor causing a severe reduction in fertility in hybrid males of Drosophila simulans and D. mauritiana. Results Our mapping effort identified a region of 9 kb on chromosome 3, containing three complete and one partial coding sequences. Within this region, two annotated genes are suggested as candidates for the HMS factor, based on the comparative molecular characterization and public-source information. Gene Taf1 is partially contained in the region, but yet shows high polymorphism with four fixed non-synonymous substitutions between the two species. Its molecular functions involve sequence-specific DNA binding and transcription factor activity. Gene agt is a small, intronless gene, whose molecular function is annotated as methylated-DNA-protein-cysteine S-methyltransferase activity. High polymorphism and one fixed non-synonymous substitution suggest this is a fast evolving gene. The gene trees of both genes perfectly separate D. simulans and D. mauritiana into monophyletic groups. Analysis of gene expression using microarray revealed trends that were similar to those previously found in comparisons between whole-genome hybrids and parental species. Conclusions The identification following confirmation of the HMS candidate gene will add another case study leading to understanding the evolutionary process of hybrid incompatibility.
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Affiliation(s)
- Luciana O Araripe
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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15
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Chang AS, Bennett SM, Noor MAF. Epistasis among Drosophila persimilis factors conferring hybrid male sterility with D. pseudoobscura bogotana. PLoS One 2010; 5:e15377. [PMID: 21060872 PMCID: PMC2965152 DOI: 10.1371/journal.pone.0015377] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 09/02/2010] [Indexed: 01/13/2023] Open
Abstract
The Bateson-Dobzhansky-Muller model posits that hybrid incompatibilities result from genetic changes that accumulate during population divergence. Indeed, much effort in recent years has been devoted to identifying genes associated with hybrid incompatibilities, often with limited success, suggesting that hybrid sterility and inviability are frequently caused by complex interactions between multiple loci and not by single or a small number of gene pairs. Our previous study showed that the nature of epistasis between sterility-conferring QTL in the Drosophila persimilis-D. pseudoobscura bogotana species pair is highly specific. Here, we further dissect one of the three QTL underlying hybrid male sterility between these species and provide evidence for multiple factors within this QTL. This result indicates that the number of loci thought to contribute to hybrid dysfunction may have been underestimated, and we discuss how linkage and complex epistasis may be characteristic of the genetics of hybrid incompatibilities. We further pinpoint the location of one locus that confers hybrid male sterility when homozygous, dubbed "mule-like", to roughly 250 kilobases.
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Affiliation(s)
- Audrey S. Chang
- Biology Department, Duke University, Durham, North Carolina, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Sarah M. Bennett
- Biology Department, Duke University, Durham, North Carolina, United States of America
| | - Mohamed A. F. Noor
- Biology Department, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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16
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Introgression of Drosophila simulans nuclear pore protein 160 in Drosophila melanogaster alone does not cause inviability but does cause female sterility. Genetics 2010; 186:669-76. [PMID: 20647504 DOI: 10.1534/genetics.110.119867] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have been analyzing genes for reproductive isolation by replacing Drosophila melanogaster genes with homologs from Drosophila simulans by interspecific backcrossing. Among the introgressions established, we found that a segment of the left arm of chromosome 2, Int(2L)S, carried recessive genes for hybrid sterility and inviability. That nuclear pore protein 160 (Nup160) in the introgression region is involved in hybrid inviability, as suggested by others, was confirmed by the present analysis. Male hybrids carrying an X chromosome of D. melanogaster were not rescued by the Lethal hybrid rescue (Lhr) mutation when the D. simulans Nup160 allele was made homozygous or hemizygous. Furthermore, we uniquely found that Nup160 is also responsible for hybrid sterility. Females were sterile when D. simulans Nup160 was made homozygous or hemizygous in the D. melanogaster genetic background. Genetic analyses indicated that the D. simulans Nup160 introgression into D. melanogaster was sufficient to cause female sterility but that other autosomal genes of D. simulans were also necessary to cause lethality. The involvement of Nup160 in hybrid inviability and female sterility was confirmed by transgene experiment.
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17
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Distinct functions of Mst77F and protamines in nuclear shaping and chromatin condensation during Drosophila spermiogenesis. Eur J Cell Biol 2010; 89:326-38. [DOI: 10.1016/j.ejcb.2009.09.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 09/17/2009] [Accepted: 09/18/2009] [Indexed: 11/23/2022] Open
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18
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A role for a neo-sex chromosome in stickleback speciation. Nature 2009; 461:1079-83. [PMID: 19783981 PMCID: PMC2776091 DOI: 10.1038/nature08441] [Citation(s) in RCA: 245] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 08/20/2009] [Indexed: 01/03/2023]
Abstract
Sexual antagonism, or conflict between the sexes, has been proposed as a driving force in both sex-chromosome turnover and speciation. Although closely related species often have different sex-chromosome systems, it is unknown whether sex-chromosome turnover contributes to the evolution of reproductive isolation between species. Here we show that a newly evolved sex chromosome contains genes that contribute to speciation in threespine stickleback fish (Gasterosteus aculeatus). We first identified a neo-sex chromosome system found only in one member of a sympatric species pair in Japan. We then performed genetic linkage mapping of male-specific traits important for reproductive isolation between the Japanese species pair. The neo-X chromosome contains loci for male courtship display traits that contribute to behavioural isolation, whereas the ancestral X chromosome contains loci for both behavioural isolation and hybrid male sterility. Our work not only provides strong evidence for a large X-effect on reproductive isolation in a vertebrate system, but also provides direct evidence that a young neo-X chromosome contributes to reproductive isolation between closely related species. Our data indicate that sex-chromosome turnover might have a greater role in speciation than was previously appreciated.
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Polymorphism in hybrid male sterility in wild-derived Mus musculus musculus strains on proximal chromosome 17. Mamm Genome 2009; 20:83-91. [PMID: 19123034 DOI: 10.1007/s00335-008-9164-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 11/25/2008] [Indexed: 10/21/2022]
Abstract
The hybrid sterility-1 (Hst1) locus at Chr 17 causes male sterility in crosses between the house mouse subspecies Mus musculus domesticus (Mmd) and M. m. musculus (Mmm). This locus has been defined by its polymorphic variants in two laboratory strains (Mmd genome) when mated to PWD/Ph mice (Mmm genome): C57BL/10 (carrying the sterile allele) and C3H (fertile allele). The occurrence of sterile and/or fertile (wild Mmm x C57BL)F1 males is evidence that polymorphism for this trait also exists in natural populations of Mmm; however, the nature of this polymorphism remains unclear. Therefore, we derived two wild-origin Mmm strains, STUS and STUF, that produce sterile and fertile males, respectively, in crosses with C57BL mice. To determine the genetic basis underlying male fertility, the (STUS x STUF)F1 females were mated to C57BL/10 J males. About one-third of resulting hybrid males (33.8%) had a significantly smaller epididymis and testes than parental animals and lacked spermatozoa due to meiotic arrest. A further one-fifth of males (20.3%) also had anomalous reproductive traits but produced some spermatozoa. The remaining fertile males (45.9%) displayed no deviation from values found in parental individuals. QTL analysis of the progeny revealed strong associations of male fitness components with the proximal end of Chr 17, and a significant effect of the central section of Chr X on testes mass. The data suggest that genetic incompatibilities associated with male sterility have evolved independently at the proximal end of Chr 17 and are polymorphic within both Mmd and Mmm genomes.
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Good JM, Dean MD, Nachman MW. A complex genetic basis to X-linked hybrid male sterility between two species of house mice. Genetics 2008; 179:2213-28. [PMID: 18689897 PMCID: PMC2516092 DOI: 10.1534/genetics.107.085340] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 06/13/2008] [Indexed: 11/18/2022] Open
Abstract
The X chromosome plays a central role in the evolution of reproductive isolation, but few studies have examined the genetic basis of X-linked incompatibilities during the early stages of speciation. We report the results of a large experiment focused on the reciprocal introgression of the X chromosome between two species of house mice, Mus musculus and M. domesticus. Introgression of the M. musculus X chromosome into a wild-derived M. domesticus genetic background produced male-limited sterility, qualitatively consistent with previous experiments using classic inbred strains to represent M. domesticus. The genetic basis of sterility involved a minimum of four X-linked factors. The phenotypic effects of major sterility QTL were largely additive and resulted in complete sterility when combined. No sterility factors were uncovered on the M. domesticus X chromosome. Overall, these results revealed a complex and asymmetric genetic basis to X-linked hybrid male sterility during the early stages of speciation in mice. Combined with data from previous studies, we identify one relatively narrow interval on the M. musculus X chromosome involved in hybrid male sterility. Only a handful of spermatogenic genes are within this region, including one of the most rapidly evolving genes on the mouse X chromosome.
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Affiliation(s)
- Jeffrey M Good
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA
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Chatterjee RN, Chatterjee P, Pal A, Pal-Bhadra M. Drosophila simulans Lethal hybrid rescue mutation (Lhr) rescues inviable hybrids by restoring X chromosomal dosage compensation and causes fluctuating asymmetry of development. J Genet 2008; 86:203-15. [PMID: 18305340 DOI: 10.1007/s12041-007-0028-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Drosophila simulans Lhr rescues lethal hybrids from the cross of D. melanogaster and D. simulans. We describe here, the phenotypes of Lhr dependent rescue hybrids and demonstrate the effects of Lhr on functional morphology of the salivary chromosomes in the hybrids. Our results reveal that the phenotypes of the 'Lhr dependent rescued' hybrids were largely dependent on the genetic background and the dominance in species and hybrids, and not on Lhr. Cytological examination reveal that while the salivary chromosome of 'larval lethal' male carrying melanogaster X chromosome was unusually thin and contracted, in 'rescued' hybrid males (C(mel)X(mel)Y(sim); A(mel)A(sim)) the X chromosome showed typical pale staining, enlarged diameter and incorporated higher rate of (3)H-uridine in presence of one dose Lhr in the genome. In hybrid males carrying simulans X chromosome (C(mel)X(sim)Y(mel); A(mel)A(sim)), enlarged width of the polytene X chromosome was noted in most of the nuclei, in Lhr background, and transcribed at higher rate than that of the single X chromosome of male. In hybrid females (both viable, e.g., C(mel)X(mel)X(sim); A(mel)A(sim) and rescued, e.g., C(mel)X(mel)X(mel); A(mel)A(sim)), the functional morphology of the X chromosomes were comparable to that of diploid autosomes in presence of one dose of Lhr. In hybrid metafemales (C(mel)X(mel)X(mel)X(sim); A(mel)A(sim)), two dose of melanogaster X chromosomes and one dose of simulans X chromosome were transcribed almost at 'female' rate in hybrid genetic background in presence of one dose of Lhr. In rescued hybrid males, the melanogaster-derived X chromosome appeared to complete its replication faster than autosomes. These results together have been interpreted to have suggested that Lhr suppresses the lethality of hybrids by regulating functional activities of the X chromosome(s) for dosage compensation.
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Affiliation(s)
- R N Chatterjee
- Department of Zoology, University of Calcutta, 35 B. C. Road, Kolkata, India.
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Putnam AS, Scriber JM, Andolfatto P. DISCORDANT DIVERGENCE TIMES AMONG Z-CHROMOSOME REGIONS BETWEEN TWO ECOLOGICALLY DISTINCT SWALLOWTAIL BUTTERFLY SPECIES. Evolution 2007; 61:912-27. [PMID: 17439621 DOI: 10.1111/j.1558-5646.2007.00076.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigate multilocus patterns of differentiation between parental populations of two swallowtail butterfly species that differ at a number of ecologically important sex-linked traits. Using a new coalescent-based approach, we show that there is significant heterogeneity in estimated divergence times among five Z-linked markers, rejecting a purely allopatric speciation model. We infer that the Z chromosome is a mosaic of regions that differ in the extent of historical gene flow, potentially due to isolating barriers that prevent the introgression of species-specific traits that result in hybrid incompatibilities. Surprisingly, a candidate region for a strong barrier to introgression, Ldh, does not show a significantly deeper divergence time than other markers on the Z chromosome. Our approach can be used to test alternative models of speciation and can potentially assign chronological order to the appearance of factors contributing to reproductive isolation between species.
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Affiliation(s)
- Andrea S Putnam
- Section of Ecology, Behavior, and Evolution, Division of Biological Sciences, University of California, San Diego, La Jolla, California 92093, USA.
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Sweigart AL, Fishman L, Willis JH. A simple genetic incompatibility causes hybrid male sterility in mimulus. Genetics 2006; 172:2465-79. [PMID: 16415357 PMCID: PMC1456371 DOI: 10.1534/genetics.105.053686] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Accepted: 01/10/2006] [Indexed: 11/18/2022] Open
Abstract
Much evidence has shown that postzygotic reproductive isolation (hybrid inviability or sterility) evolves by the accumulation of interlocus incompatibilities between diverging populations. Although in theory only a single pair of incompatible loci is needed to isolate species, empirical work in Drosophila has revealed that hybrid fertility problems often are highly polygenic and complex. In this article we investigate the genetic basis of hybrid sterility between two closely related species of monkeyflower, Mimulus guttatus and M. nasutus. In striking contrast to Drosophila systems, we demonstrate that nearly complete hybrid male sterility in Mimulus results from a simple genetic incompatibility between a single pair of heterospecific loci. We have genetically mapped this sterility effect: the M. guttatus allele at the hybrid male sterility 1 (hms1) locus acts dominantly in combination with recessive M. nasutus alleles at the hybrid male sterility 2 (hms2) locus to cause nearly complete hybrid male sterility. In a preliminary screen to find additional small-effect male sterility factors, we identified one additional locus that also contributes to some of the variation in hybrid male fertility. Interestingly, hms1 and hms2 also cause a significant reduction in hybrid female fertility, suggesting that sex-specific hybrid defects might share a common genetic basis. This possibility is supported by our discovery that recombination is reduced dramatically in a cross involving a parent with the hms1-hms2 incompatibility.
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Affiliation(s)
- Andrea L Sweigart
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.
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Torgerson DG, Whitty BR, Singh RS. Sex-Specific Functional Specialization and the Evolutionary Rates of Essential Fertility Genes. J Mol Evol 2005; 61:650-8. [PMID: 16245009 DOI: 10.1007/s00239-005-0007-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Accepted: 06/07/2005] [Indexed: 11/30/2022]
Abstract
Genes related to sex and reproduction are known to evolve rapidly, however, the mechanism for rapid evolutionary change is proving to be more complex than a simple relaxation of selective constraint. We compared the divergence between orthologous human and mouse fertility genes according to their degree of dispensability as suggested by mouse knockout mutation phenotypes. The dataset consisted of 161 orthologous genes affecting fertility and 803 orthologous genes affecting viability. We find that essential fertility genes affecting both sexes evolve at a similar rate as essential viability genes, but that within sexes the degree of dispensability is not an important factor affecting the rate of fertility gene evolution. We also find no difference in the evolutionary rates of fertility genes that affect the male versus the female, however, there are a greater number of sterility genes that affect the male. Generally there are a significantly greater number of fertility genes that affect one sex rather than both, suggesting that fertility genes tend toward sex-specific functions, particularly in the male. Our findings support the hypothesis that the rapid evolution of sex- and reproduction-related genes is facilitated through an increased specialization of gene function and that dispensability is not a major factor determining their evolutionary rate.
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Affiliation(s)
- Dara G Torgerson
- Department of Biology, McMaster University, Hamilton, Ontario L8S 1J4, Canada.
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Dworkin I, Palsson A, Gibson G. Replication of an Egfr-wing shape association in a wild-caught cohort of Drosophila melanogaster. Genetics 2005; 169:2115-25. [PMID: 15687273 PMCID: PMC1449590 DOI: 10.1534/genetics.104.035766] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 01/10/2005] [Indexed: 11/18/2022] Open
Abstract
Linkage disequilibrium mapping has been used extensively in medical and evolutionary genetics to map causal polymorphisms within genes associated with disease status or phenotypic variation for a trait. However, the initial findings of most nonhuman studies have not been replicated in subsequent studies, due in part to false positives, as well as additional factors that can render true positives unreplicable. These factors may be more severe when the initial study is performed using an experimental population of organisms reared under controlled lab conditions. We demonstrate that despite considerable phenotypic differences for wing shape between a lab-reared experimental population and a wild-caught cohort of Drosophila melanogaster, an association between a putative regulatory polymorphism in Egfr and wing shape can be replicated. These results are discussed both within the framework of future association-mapping studies and within the context of the evolutionary dynamics of alleles in populations.
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Affiliation(s)
- Ian Dworkin
- Department of Genetics, North Carolina State University, Raleigh, 27695-7614, USA.
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Abstract
Until recently, the genes that cause reproductive isolation remained black boxes. Consequently, evolutionary biologists were unable to answer several questions about the identities and characteristics of "speciation genes". Over the past few years, however, evolutionary geneticists have finally succeeded in isolating several such genes, providing our first glimpse at factors that are thought to be representative of those underlying the origin of species. Evolutionary analysis of these genes suggests that speciation results from positive Darwinian selection within species. Molecular evolutionary study of the genes causing reproductive isolation may represent an important new phase in the study of speciation.
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Affiliation(s)
- H Allen Orr
- Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY 14853, USA.
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