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Hunnicutt KE, Callahan C, Keeble S, Moore EC, Good JM, Larson EL. Different complex regulatory phenotypes underlie hybrid male sterility in divergent rodent crosses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.30.564782. [PMID: 37961317 PMCID: PMC10634954 DOI: 10.1101/2023.10.30.564782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Hybrid incompatibilities are a critical component of species barriers and may arise due to negative interactions between divergent regulatory elements in parental species. We used a comparative approach to identify common themes in the regulatory phenotypes associated with hybrid male sterility in two divergent rodent crosses, dwarf hamsters and house mice. We investigated three potential characteristic gene expression phenotypes in hybrids including the propensity of transgressive differentially expressed genes in hybrids towards over or underexpression relative to parental species, the influence of developmental stage on the extent of misexpression, and the role of the sex chromosomes on misexpression phenotypes. In contrast to near pervasive overexpression in hybrid house mice, we found that misexpression in hybrid dwarf hamsters was dependent on developmental stage. In both house mouse and dwarf hamster hybrids, however, transgressive misexpression increased with the progression of spermatogenesis, although to varying extents and with potentially different consequences. In both systems, we detected sex-chromosome specific overexpression in stages of spermatogenesis where inactivated X chromosome expression was expected, but the hybrid overexpression phenotypes were fundamentally different. Importantly, misexpression phenotypes support the presence of multiple developmental blocks to spermatogenesis in dwarf hamster hybrids, including a potential role of meiotic stalling or breakdown early in spermatogenesis. Collectively, we demonstrate that while there are some similarities in hybrid expression phenotypes of house mice and dwarf hamsters, there are also clear differences that point towards unique mechanisms underlying hybrid male sterility in each system. Our results highlight the potential of comparative approaches in helping to understand the causes and consequences of disrupted gene expression in speciation.
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Affiliation(s)
| | - Colin Callahan
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812
| | - Sara Keeble
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812
| | - Emily C. Moore
- University of Denver, Department of Biological Sciences, Denver, CO, 80208
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812
| | - Jeffrey M. Good
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812
| | - Erica L. Larson
- University of Denver, Department of Biological Sciences, Denver, CO, 80208
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2
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Erkine AM, Oliveira MA, Class CA. The Enigma of Transcriptional Activation Domains. J Mol Biol 2024; 436:168766. [PMID: 39214280 DOI: 10.1016/j.jmb.2024.168766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 08/22/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024]
Abstract
Activation domains (ADs) of eukaryotic gene activators remain enigmatic for decades as short, extremely variable sequences which often are intrinsically disordered in structure and interact with an uncertain number of targets. The general absence of specificity increasingly complicates the utilization of the widely accepted mechanism of AD function by recruitment of coactivators. The long-standing enigma at the heart of molecular biology demands a fundamental rethinking of established concepts. Here, we review the experimental evidence supporting a novel mechanistic model of gene activation, based on ADs functioning via surfactant-like near-stochastic interactions with gene promoter nucleosomes. This new model is consistent with recent information-rich experimental data obtained using high-throughput synthetic biology and bioinformatics analysis methods, including machine learning. We clarify why the conventional biochemical principle of specificity for sequence, structures, and interactions fails to explain activation domain function. This perspective provides connections to the liquid-liquid phase separation model, signifies near-stochastic interactions as fundamental for the biochemical function, and can be generalized to other cellular functions.
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3
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Majane AC, Cridland JM, Blair LK, Begun DJ. Evolution and genetics of accessory gland transcriptome divergence between Drosophila melanogaster and D. simulans. Genetics 2024; 227:iyae039. [PMID: 38518250 PMCID: PMC11151936 DOI: 10.1093/genetics/iyae039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 08/27/2023] [Accepted: 02/15/2024] [Indexed: 03/24/2024] Open
Abstract
Studies of allele-specific expression in interspecific hybrids have provided important insights into gene-regulatory divergence and hybrid incompatibilities. Many such investigations in Drosophila have used transcriptome data from complex mixtures of many tissues or from gonads, however, regulatory divergence may vary widely among species, sexes, and tissues. Thus, we lack sufficiently broad sampling to be confident about the general biological principles of regulatory divergence. Here, we seek to fill some of these gaps in the literature by characterizing regulatory evolution and hybrid misexpression in a somatic male sex organ, the accessory gland, in F1 hybrids between Drosophila melanogaster and D. simulans. The accessory gland produces seminal fluid proteins, which play an important role in male and female fertility and may be subject to adaptive divergence due to male-male or male-female interactions. We find that trans differences are relatively more abundant than cis, in contrast to most of the interspecific hybrid literature, though large effect-size trans differences are rare. Seminal fluid protein genes have significantly elevated levels of expression divergence and tend to be regulated through both cis and trans divergence. We find limited misexpression (over- or underexpression relative to both parents) in this organ compared to most other Drosophila studies. As in previous studies, male-biased genes are overrepresented among misexpressed genes and are much more likely to be underexpressed. ATAC-Seq data show that chromatin accessibility is correlated with expression differences among species and hybrid allele-specific expression. This work identifies unique regulatory evolution and hybrid misexpression properties of the accessory gland and suggests the importance of tissue-specific allele-specific expression studies.
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Affiliation(s)
- Alex C Majane
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
| | - Julie M Cridland
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
| | - Logan K Blair
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
| | - David J Begun
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA
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4
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Yazdi HP, Ravinet M, Rowe M, Saetre GP, Guldvog CØ, Eroukhmanoff F, Marzal A, Magallanes S, Runemark A. Extensive transgressive gene expression in testis but not ovary in the homoploid hybrid Italian sparrow. Mol Ecol 2022; 31:4067-4077. [PMID: 35726533 PMCID: PMC9542029 DOI: 10.1111/mec.16572] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 05/01/2022] [Accepted: 05/12/2022] [Indexed: 11/30/2022]
Abstract
Hybridization can result in novel allelic combinations which can impact the hybrid phenotype through changes in gene expression. While misexpression in F1 hybrids is well documented, how gene expression evolves in stabilized hybrid taxa remains an open question. As gene expression evolves in a stabilizing manner, break‐up of co‐evolved cis‐ and trans‐regulatory elements could lead to transgressive patterns of gene expression in hybrids. Here, we address to what extent gonad gene expression has evolved in an established and stable homoploid hybrid, the Italian sparrow (Passer italiae). Through comparison of gene expression in gonads from individuals of the two parental species (i.e., house and Spanish sparrow) to that of Italian sparrows, we find evidence for strongly transgressive expression in male Italian sparrows—2530 genes (22% of testis genes tested for inheritance) exhibit expression patterns outside the range of both parent species. In contrast, Italian sparrow ovary expression was similar to that of one of the parent species, the house sparrow (Passer domesticus). Moreover, the Italian sparrow testis transcriptome is 26 times as diverged from those of the parent species as the parental transcriptomes are from each other, despite being genetically intermediate. This highlights the potential for regulation of gene expression to produce novel variation following hybridization. Genes involved in mitochondrial respiratory chain complexes and protein synthesis are enriched in the subset that is over‐dominantly expressed in Italian sparrow testis, suggesting that selection on key functions has moulded the hybrid Italian sparrow transcriptome.
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Affiliation(s)
| | - Mark Ravinet
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Melissah Rowe
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), AB, Wageningen, The Netherlands
| | - Glenn-Peter Saetre
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, PO, Oslo, Norway
| | - Caroline Øien Guldvog
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, PO, Oslo, Norway
| | - Fabrice Eroukhmanoff
- Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, PO, Oslo, Norway
| | - Alfonso Marzal
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Badajoz, Spain
| | - Sergio Magallanes
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Badajoz, Spain.,Department of Wetland Ecology, Doñana Biological Station (EBD-CSIC), Avda. Américo Vespucio, 41092, Seville, Spain
| | - Anna Runemark
- Department of Biology, Lund University, Lund, Sweden
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5
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A microscopy investigation of the complex problem of infertility of insect hybrids. Studies on the reproductive systems, eggshells, and karyotypes of the representatives of the genus Platymeris (Heteroptera, Reduviidae) and their hybrids. Micron 2022; 158:103248. [DOI: 10.1016/j.micron.2022.103248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 01/08/2023]
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6
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Abstract
Even if a species' phenotype does not change over evolutionary time, the underlying mechanism may change, as distinct molecular pathways can realize identical phenotypes. Here we use linear system theory to explore the consequences of this idea, describing how a gene network underlying a conserved phenotype evolves, as the genetic drift of small changes to these molecular pathways causes a population to explore the set of mechanisms with identical phenotypes. To do this, we model an organism's internal state as a linear system of differential equations for which the environment provides input and the phenotype is the output, in which context there exists an exact characterization of the set of all mechanisms that give the same input-output relationship. This characterization implies that selectively neutral directions in genotype space should be common and that the evolutionary exploration of these distinct but equivalent mechanisms can lead to the reproductive incompatibility of independently evolving populations. This evolutionary exploration, or system drift, is expected to proceed at a rate proportional to the amount of intrapopulation genetic variation divided by the effective population size ( Ne$N_e$ ). At biologically reasonable parameter values this could lead to substantial interpopulation incompatibility, and thus speciation, on a time scale of Ne$N_e$ generations. This model also naturally predicts Haldane's rule, thus providing a concrete explanation of why heterogametic hybrids tend to be disrupted more often than homogametes during the early stages of speciation.
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Affiliation(s)
- Joshua S. Schiffman
- New York Genome CenterNew YorkNew York 10013,Weill Cornell MedicineNew YorkNew York 10065,Department of Molecular and Computational BiologyUniversity of Southern CaliforniaLos AngelesCalifornia 90089
| | - Peter L. Ralph
- Department of Molecular and Computational BiologyUniversity of Southern CaliforniaLos AngelesCalifornia 90089,Department of Mathematics, Institute of Ecology and EvolutionUniversity of OregonEugeneOregon 97403,Department of Biology, Institute of Ecology and EvolutionUniversity of OregonEugeneOregon 97403
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7
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Environment-Dependent Heterosis and Transgressive Gene Expression in Reciprocal Hybrids between the Channel Catfish Ictalurus punctatus and the Blue Catfish Ictalurus furcatus. BIOLOGY 2022; 11:biology11010117. [PMID: 35053114 PMCID: PMC8772901 DOI: 10.3390/biology11010117] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 12/13/2022]
Abstract
The hybrid between female channel catfish (Ictalurus punctatus) and male blue catfish (Ictalurus furcatus) is superior in feed conversion, disease resistance, carcass yield, and harvestability compared to both parental species. However, heterosis and heterobeltiosis only occur in pond culture, and channel catfish grow much faster than the other genetic types in small culture units. This environment-dependent heterosis is intriguing, but the underlying genetic mechanisms are not well understood. In this study, phenotypic characterization and transcriptomic analyses were performed in the channel catfish, blue catfish, and their reciprocal F1s reared in tanks. The results showed that the channel catfish is superior in growth-related morphometrics, presumably due to significantly lower innate immune function, as investigated by reduced lysozyme activity and alternative complement activity. RNA-seq analysis revealed that genes involved in fatty acid metabolism/transport are significantly upregulated in channel catfish compared to blue catfish and hybrids, which also contributes to the growth phenotype. Interestingly, hybrids have a 40-80% elevation in blood glucose than the parental species, which can be explained by a phenomenon called transgressive expression (overexpression/underexpression in F1s than the parental species). A total of 1140 transgressive genes were identified in F1 hybrids, indicating that 8.5% of the transcriptome displayed transgressive expression. Transgressive genes upregulated in F1s are enriched for glycan degradation function, directly related to the increase in blood glucose level. This study is the first to explore molecular mechanisms of environment-dependent heterosis/heterobeltiosis in a vertebrate species and sheds light on the regulation and evolution of heterosis vs. hybrid incompatibility.
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8
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Neural divergence and hybrid disruption between ecologically isolated Heliconius butterflies. Proc Natl Acad Sci U S A 2021; 118:2015102118. [PMID: 33547240 DOI: 10.1073/pnas.2015102118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The importance of behavioral evolution during speciation is well established, but we know little about how this is manifest in sensory and neural systems. A handful of studies have linked specific neural changes to divergence in host or mate preferences associated with speciation. However, the degree to which brains are adapted to local environmental conditions, and whether this contributes to reproductive isolation between close relatives that have diverged in ecology, remains unknown. Here, we examine divergence in brain morphology and neural gene expression between closely related, but ecologically distinct, Heliconius butterflies. Despite ongoing gene flow, sympatric species pairs within the melpomene-cydno complex are consistently separated across a gradient of open to closed forest and decreasing light intensity. By generating quantitative neuroanatomical data for 107 butterflies, we show that Heliconius melpomene and Heliconius cydno clades have substantial shifts in brain morphology across their geographic range, with divergent structures clustered in the visual system. These neuroanatomical differences are mirrored by extensive divergence in neural gene expression. Differences in both neural morphology and gene expression are heritable, exceed expected rates of neutral divergence, and result in intermediate traits in first-generation hybrid offspring. Strong evidence of divergent selection implies local adaptation to distinct selective optima in each parental microhabitat, suggesting the intermediate traits of hybrids are poorly matched to either condition. Neural traits may therefore contribute to coincident barriers to gene flow, thereby helping to facilitate speciation.
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9
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Banho CA, Mérel V, Oliveira TYK, Carareto CMA, Vieira C. Comparative transcriptomics between Drosophila mojavensis and D. arizonae reveals transgressive gene expression and underexpression of spermatogenesis-related genes in hybrid testes. Sci Rep 2021; 11:9844. [PMID: 33972659 PMCID: PMC8110761 DOI: 10.1038/s41598-021-89366-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/19/2021] [Indexed: 01/02/2023] Open
Abstract
Interspecific hybridization is a stressful condition that can lead to sterility and/or inviability through improper gene regulation in Drosophila species with a high divergence time. However, the extent of these abnormalities in hybrids of recently diverging species is not well known. Some studies have shown that in Drosophila, the mechanisms of postzygotic isolation may evolve more rapidly in males than in females and that the degree of viability and sterility is associated with the genetic distance between species. Here, we used transcriptomic comparisons between two Drosophila mojavensis subspecies and D. arizonae (repleta group, Drosophila) and identified greater differential gene expression in testes than in ovaries. We tested the hypothesis that the severity of the interspecies hybrid phenotype is associated with the degree of gene misregulation. We showed limited gene misregulation in fertile females and an increase in the amount of misregulation in males with more severe sterile phenotypes (motile vs. amotile sperm). In addition, for these hybrids, we identified candidate genes that were mostly associated with spermatogenesis dysfunction.
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Affiliation(s)
- Cecilia A Banho
- Department of Biology, UNESP - São Paulo State University, São José do Rio Preto, São Paulo State (SP), Brazil.,Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France
| | - Vincent Mérel
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France
| | - Thiago Y K Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY, USA
| | - Claudia M A Carareto
- Department of Biology, UNESP - São Paulo State University, São José do Rio Preto, São Paulo State (SP), Brazil
| | - Cristina Vieira
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Claude Bernard Lyon 1, University of Lyon, 69622, Villeurbanne, France.
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10
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Kerwin RE, Sweigart AL. Rampant Misexpression in a Mimulus (Monkeyflower) Introgression Line Caused by Hybrid Sterility, Not Regulatory Divergence. Mol Biol Evol 2021; 37:2084-2098. [PMID: 32196085 PMCID: PMC7306685 DOI: 10.1093/molbev/msaa071] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Divergence in gene expression regulation is common between closely related species and may give rise to incompatibilities in their hybrid progeny. In this study, we investigated the relationship between regulatory evolution within species and reproductive isolation between species. We focused on a well-studied case of hybrid sterility between two closely related yellow monkeyflower species, Mimulus guttatus and Mimulus nasutus, that is caused by two epistatic loci, hybrid male sterility 1 (hms1) and hybrid male sterility 2 (hms2). We compared genome-wide transcript abundance across male and female reproductive tissues (i.e., stamens and carpels) from four genotypes: M. guttatus, M. nasutus, and sterile and fertile progeny from an advanced M. nasutus–M. guttatus introgression line carrying the hms1–hms2 incompatibility. We observed substantial variation in transcript abundance between M. guttatus and M. nasutus, including distinct but overlapping patterns of tissue-biased expression, providing evidence for regulatory divergence between these species. We also found rampant genome-wide misexpression, but only in the affected tissues (i.e., stamens) of sterile introgression hybrids carrying incompatible alleles at hms1 and hms2. Examining patterns of allele-specific expression in sterile and fertile introgression hybrids, we found evidence for interspecific divergence in cis- and trans-regulation, including compensatory cis–trans mutations likely to be driven by stabilizing selection. Nevertheless, species divergence in gene regulatory networks cannot explain the vast majority of the gene misexpression we observe in Mimulus introgression hybrids, which instead likely manifests as a downstream consequence of sterility itself.
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Affiliation(s)
- Rachel E Kerwin
- Department of Genetics, University of Georgia, Athens, GA.,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI
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11
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Liu Y, El-Kassaby YA. Transcriptome-wide analysis of introgression-resistant regions reveals genetic divergence genes under positive selection in Populus trichocarpa. Heredity (Edinb) 2021; 126:442-462. [PMID: 33214679 PMCID: PMC8027638 DOI: 10.1038/s41437-020-00388-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 11/04/2020] [Accepted: 11/04/2020] [Indexed: 11/09/2022] Open
Abstract
Comparing gene expression patterns and genetic polymorphisms between populations is of central importance for understanding the origin and maintenance of biodiversity. Based on population-specific gene expression levels and allele frequency differences, we sought to identify population divergence (PD) genes across the introgression-resistant genomic regions of Populus trichocarpa. Genes containing highly diverged loci [i.e., genetic divergence (GD)] or showing expression divergence (ED) between populations were widely distributed in the genome and substantially enriched in functional categories related to stress responses, disease resistance, timing of flowering, cell cycle regulation, plant growth, and development. Nine genomic regions showing evidence of strong positive selection were overlapped with GD genes, which had significant differences between Oregon (a southernmost peripheral deme) and the other demes. However, we did not find evidence that genes under positive selection show an enrichment for ED. PD genes and genes under selection pertained to the same gene classes, such as SERINE/CYSTEINE PROTEASE, ABC TRANSPORTER, GLYCOSYLTRANSFERASE and other transferases. Our analysis also revealed that GD genes were polymorphic within the species (41.9 ± 3.66 biallelic variants per gene), as previously reported in herbaceous plants. By contrast, ED genes contained less genetic variants (10.73 ± 1.14) and were likely highly expressed. In addition, we found that trans- rather than cis-acting variants considerably contribute to the evolution of >90% PD genes. Overall, this study elucidates that cohorts of PD genes agree with the general attributes of known speciation genes and GD genes will provide substrates for positive selection to operate on.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
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12
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Adashev VE, Kotov AA, Bazylev SS, Shatskikh AS, Aravin AA, Olenina LV. Stellate Genes and the piRNA Pathway in Speciation and Reproductive Isolation of Drosophila melanogaster. Front Genet 2021; 11:610665. [PMID: 33584811 PMCID: PMC7874207 DOI: 10.3389/fgene.2020.610665] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 12/29/2020] [Indexed: 12/12/2022] Open
Abstract
One of the main conditions of the species splitting from a common precursor lineage is the prevention of a gene flow between diverging populations. The study of Drosophila interspecific hybrids allows to reconstruct the speciation mechanisms and to identify hybrid incompatibility factors that maintain post-zygotic reproductive isolation between closely related species. The regulation, evolution, and maintenance of the testis-specific Ste-Su(Ste) genetic system in Drosophila melanogaster is the subject of investigation worldwide. X-linked tandem testis-specific Stellate genes encode proteins homologous to the regulatory β-subunit of protein kinase CK2, but they are permanently repressed in wild-type flies by the piRNA pathway via piRNAs originating from the homologous Y-linked Su(Ste) locus. Derepression of Stellate genes caused by Su(Ste) piRNA biogenesis disruption leads to the accumulation of crystalline aggregates in spermatocytes, meiotic defects and male sterility. In this review we summarize current data about the origin, organization, evolution of the Ste-Su(Ste) system, and piRNA-dependent regulation of Stellate expression. The Ste-Su(Ste) system is fixed only in the D. melanogaster genome. According to our hypothesis, the acquisition of the Ste-Su(Ste) system by a part of the ancient fly population appears to be the causative factor of hybrid sterility in crosses of female flies with males that do not carry Y-linked Su(Ste) repeats. To support this scenario, we have directly demonstrated Stellate derepression and the corresponding meiotic disorders in the testes of interspecies hybrids between D. melanogaster and D. mauritiana. This finding embraces our hypothesis about the contribution of the Ste-Su(Ste) system and the piRNA pathway to the emergence of reproductive isolation of D. melanogaster lineage from initial species.
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Affiliation(s)
- Vladimir E. Adashev
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, National Research Centre “Kurchatov Institute”, Moscow, Russia
| | - Alexei A. Kotov
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, National Research Centre “Kurchatov Institute”, Moscow, Russia
| | - Sergei S. Bazylev
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, National Research Centre “Kurchatov Institute”, Moscow, Russia
| | - Aleksei S. Shatskikh
- Laboratory of Analysis of Clinical and Model Tumor Pathologies at the Organismal Level, Institute of Molecular Genetics, National Research Centre “Kurchatov Institute”, Moscow, Russia
| | - Alexei A. Aravin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Ludmila V. Olenina
- Laboratory of Biochemical Genetics of Animals, Institute of Molecular Genetics, National Research Centre “Kurchatov Institute”, Moscow, Russia
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13
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Go AC, Civetta A. Hybrid Incompatibilities and Transgressive Gene Expression Between Two Closely Related Subspecies of Drosophila. Front Genet 2020; 11:599292. [PMID: 33362859 PMCID: PMC7758320 DOI: 10.3389/fgene.2020.599292] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/12/2020] [Indexed: 11/13/2022] Open
Abstract
Genome-wide assays of expression between species and their hybrids have identified genes that become either over- or underexpressed relative to the parental species (i.e., transgressive). Transgressive expression in hybrids is of interest because it highlights possible changes in gene regulation linked to hybrid dysfunction. Previous studies in Drosophila that used long-diverged species pairs with complete or nearly complete isolation (i.e., full sterility and partial inviability of hybrids) and high-levels of genome misregulation have found correlations between expression and coding sequence divergence. The work highlighted the possible effects of directional selection driving sequence divergence and transgressive expression. Whether the same is true for taxa at early stages of divergence that have only achieved partial isolation remains untested. Here, we reanalyze previously published genome expression data and available genome sequence reads from a pair of partially isolated subspecies of Drosophila to compare expression and sequence divergence. We find a significant correlation in rates of expression and sequence evolution, but no support for directional selection driving transgressive expression in hybrids. We find that most transgressive genes in hybrids show no differential expression between parental subspecies and used SNP data to explore the role of stabilizing selection through compensatory mutations. We also examine possible misregulation through cascade effects that could be driven by interacting gene networks or co-option of off-target cis-regulatory elements.
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Affiliation(s)
- Alwyn C Go
- Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada
| | - Alberto Civetta
- Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada
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14
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Mugal CF, Wang M, Backström N, Wheatcroft D, Ålund M, Sémon M, McFarlane SE, Dutoit L, Qvarnström A, Ellegren H. Tissue-specific patterns of regulatory changes underlying gene expression differences among Ficedula flycatchers and their naturally occurring F 1 hybrids. Genome Res 2020; 30:1727-1739. [PMID: 33144405 PMCID: PMC7706733 DOI: 10.1101/gr.254508.119] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/28/2020] [Indexed: 12/27/2022]
Abstract
Changes in interacting cis- and trans-regulatory elements are important candidates for Dobzhansky-Muller hybrid incompatibilities and may contribute to hybrid dysfunction by giving rise to misexpression in hybrids. To gain insight into the molecular mechanisms and determinants of gene expression evolution in natural populations, we analyzed the transcriptome from multiple tissues of two recently diverged Ficedula flycatcher species and their naturally occurring F1 hybrids. Differential gene expression analysis revealed that the extent of differentiation between species and the set of differentially expressed genes varied across tissues. Common to all tissues, a higher proportion of Z-linked genes than autosomal genes showed differential expression, providing evidence for a fast-Z effect. We further found clear signatures of hybrid misexpression in brain, heart, kidney, and liver. However, while testis showed the highest divergence of gene expression among tissues, it showed no clear signature of misexpression in F1 hybrids, even though these hybrids were found to be sterile. It is therefore unlikely that incompatibilities between cis-trans regulatory changes explain the observed sterility. Instead, we found evidence that cis-regulatory changes play a significant role in the evolution of gene expression in testis, which illustrates the tissue-specific nature of cis-regulatory evolution bypassing constraints associated with pleiotropic effects of genes.
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Affiliation(s)
- Carina F Mugal
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden
| | - Mi Wang
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden
| | - Niclas Backström
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden
| | - David Wheatcroft
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.,Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
| | - Murielle Ålund
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.,Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Marie Sémon
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.,ENS de Lyon, Laboratory of Biology and Modelling of the Cell, Lyon University, 69364 Lyon Cedex 07, France
| | - S Eryn McFarlane
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.,Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Ludovic Dutoit
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden.,Department of Zoology, University of Otago, Dunedin 9016, New Zealand
| | - Anna Qvarnström
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden
| | - Hans Ellegren
- Department of Ecology and Genetics, Uppsala University, 752 36 Uppsala, Sweden
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15
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Matveevsky S, Tretiakov A, Kashintsova A, Bakloushinskaya I, Kolomiets O. Meiotic Nuclear Architecture in Distinct Mole Vole Hybrids with Robertsonian Translocations: Chromosome Chains, Stretched Centromeres, and Distorted Recombination. Int J Mol Sci 2020; 21:E7630. [PMID: 33076404 PMCID: PMC7589776 DOI: 10.3390/ijms21207630] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 10/13/2020] [Indexed: 11/24/2022] Open
Abstract
Genome functioning in hybrids faces inconsistency. This mismatch is manifested clearly in meiosis during chromosome synapsis and recombination. Species with chromosomal variability can be a model for exploring genomic battles with high visibility due to the use of advanced immunocytochemical methods. We studied synaptonemal complexes (SC) and prophase I processes in 44-chromosome intraspecific (Ellobius tancrei × E. tancrei) and interspecific (Ellobius talpinus × E. tancrei) hybrid mole voles heterozygous for 10 Robertsonian translocations. The same pachytene failures were found for both types of hybrids. In the intraspecific hybrid, the chains were visible in the pachytene stage, then 10 closed SC trivalents formed in the late pachytene and diplotene stage. In the interspecific hybrid, as a rule, SC trivalents composed the SC chains and rarely could form closed configurations. Metacentrics involved with SC trivalents had stretched centromeres in interspecific hybrids. Linkage between neighboring SC trivalents was maintained by stretched centromeric regions of acrocentrics. This centromeric plasticity in structure and dynamics of SC trivalents was found for the first time. We assume that stretched centromeres were a marker of altered nuclear architecture in heterozygotes due to differences in the ancestral chromosomal territories of the parental species. Restructuring of the intranuclear organization and meiotic disturbances can contribute to the sterility of interspecific hybrids, and lead to the reproductive isolation of studied species.
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Affiliation(s)
- Sergey Matveevsky
- Laboratory of Cytogenetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.T.); (A.K.); (O.K.)
| | - Artemii Tretiakov
- Laboratory of Cytogenetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.T.); (A.K.); (O.K.)
| | - Anna Kashintsova
- Laboratory of Cytogenetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.T.); (A.K.); (O.K.)
| | - Irina Bakloushinskaya
- Laboratory of Genome Evolution and Mechanisms of Speciation, Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia;
| | - Oxana Kolomiets
- Laboratory of Cytogenetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, 119991 Moscow, Russia; (A.T.); (A.K.); (O.K.)
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16
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Satokangas I, Martin SH, Helanterä H, Saramäki J, Kulmuni J. Multi-locus interactions and the build-up of reproductive isolation. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190543. [PMID: 32654649 PMCID: PMC7423273 DOI: 10.1098/rstb.2019.0543] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2020] [Indexed: 12/15/2022] Open
Abstract
All genes interact with other genes, and their additive effects and epistatic interactions affect an organism's phenotype and fitness. Recent theoretical and empirical work has advanced our understanding of the role of multi-locus interactions in speciation. However, relating different models to one another and to empirical observations is challenging. This review focuses on multi-locus interactions that lead to reproductive isolation (RI) through reduced hybrid fitness. We first review theoretical approaches and show how recent work incorporating a mechanistic understanding of multi-locus interactions recapitulates earlier models, but also makes novel predictions concerning the build-up of RI. These include high variance in the build-up rate of RI among taxa, the emergence of strong incompatibilities producing localized barriers to introgression, and an effect of population size on the build-up of RI. We then review recent experimental approaches to detect multi-locus interactions underlying RI using genomic data. We argue that future studies would benefit from overlapping methods like ancestry disequilibrium scans, genome scans of differentiation and analyses of hybrid gene expression. Finally, we highlight a need for further overlap between theoretical and empirical work, and approaches that predict what kind of patterns multi-locus interactions resulting in incompatibilities will leave in genome-wide polymorphism data. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- I. Satokangas
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1, PO Box 65, 00014 Helsinki, Finland
| | - S. H. Martin
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh EH9 3FL, UK
| | - H. Helanterä
- Ecology and Genetics research unit, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - J. Saramäki
- Department of Computer Science, Aalto University, PO Box 11000, 00076 Aalto, Espoo, Finland
| | - J. Kulmuni
- Organismal & Evolutionary Biology Research Programme, University of Helsinki, Viikinkaari 1, PO Box 65, 00014 Helsinki, Finland
- Tvärminne Zoological Station, University of Helsinki, J. A. Palménin tie 260, 10900 Hanko, Finland
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17
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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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18
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McGirr JA, Martin CH. Hybrid gene misregulation in multiple developing tissues within a recent adaptive radiation of Cyprinodon pupfishes. PLoS One 2019; 14:e0218899. [PMID: 31291291 PMCID: PMC6619667 DOI: 10.1371/journal.pone.0218899] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/11/2019] [Indexed: 12/24/2022] Open
Abstract
Genetic incompatibilities constitute the final stages of reproductive isolation and speciation, but little is known about incompatibilities that occur within recent adaptive radiations among closely related diverging populations. Crossing divergent species to form hybrids can break up coadapted variation, resulting in genetic incompatibilities within developmental networks shaping divergent adaptive traits. We crossed two closely related sympatric Cyprinodon pupfish species–a dietary generalist and a specialized molluscivore–and measured expression levels in their F1 hybrids to identify regulatory variation underlying the novel craniofacial morphology found in this recent microendemic adaptive radiation. We extracted mRNA from eight day old whole-larvae tissue and from craniofacial tissues dissected from 17–20 day old larvae to compare gene expression between a total of seven F1 hybrids and 24 individuals from parental species populations. We found 3.9% of genes differentially expressed between generalists and molluscivores in whole-larvae tissues and 0.6% of genes differentially expressed in craniofacial tissue. We found that 2.1% of genes were misregulated in whole-larvae hybrids whereas 19.1% of genes were misregulated in hybrid craniofacial tissues, after correcting for sequencing biases. We also measured allele specific expression across 15,429 heterozygous sites to identify putative compensatory regulatory mechanisms underlying differential expression between generalists and molluscivores. Together, our results highlight the importance of considering misregulation as an early indicator of genetic incompatibilities in the context of rapidly diverging adaptive radiations and suggests that compensatory regulatory divergence drives hybrid gene misregulation in developing tissues that give rise to novel craniofacial traits.
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Affiliation(s)
- Joseph A. McGirr
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| | - Christopher H. Martin
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, California, United States of America
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19
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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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20
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Zhong Z, Lin L, Chen M, Lin L, Chen X, Lin Y, Chen X, Wang Z, Norvienyeku J, Zheng H. Expression Divergence as an Evolutionary Alternative Mechanism Adopted by Two Rice Subspecies Against Rice Blast Infection. RICE (NEW YORK, N.Y.) 2019; 12:12. [PMID: 30825020 PMCID: PMC6397267 DOI: 10.1186/s12284-019-0270-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/18/2019] [Indexed: 05/30/2023]
Abstract
BACKGROUND Rice (Oryza sativa L.) is one of the most important crops that serves as staple food for ~ 50% of the human population worldwide. Some important agronomic traits that allow rice to cope with numerous abiotic and biotic stresses have been selected and fixed during domestication. Knowledge on how expression divergence of genes gradually contributes to phenotypic differentiation in response to biotic stress and their contribution to rice population speciation is still limited. RESULTS Here, we explored gene expression divergence between a japonica rice cultivar Nipponbare and an indica rice cultivar 93-11 in response to invasion by the filamentous ascomycete fungus Magnaporthe oryzae (Pyricularia oryzae), a plant pathogen that causes significant loss to rice production worldwide. We investigated differentially expressed genes in the two cultivars and observed that evolutionarily conserved orthologous genes showed highly variable expression patterns under rice blast infection. Analysis of promoter region of these differentially expressed orthologous genes revealed the existence of cis-regulatory elements associated with the differentiated expression pattern of these genes in the two rice cultivars. Further comparison of these regions in global rice population indicated their fixation and close relationship with rice population divergence. CONCLUSION We proposed that variation in the expression patterns of these orthologous genes mediated by cis-regulatory elements in the two rice cultivars, may constitute an alternative evolutionary mechanism that distinguishes these two genetically and ecologically divergent rice cultivars in response to M. oryzae infection.
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Affiliation(s)
- Zhenhui Zhong
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Lianyu Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Meilian Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Lili Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Xiaofeng Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Yahong Lin
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Xi Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Institute of Oceanography, Minjiang University, Fuzhou, 350108 China
| | - Justice Norvienyeku
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Huakun Zheng
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Fujian-Taiwan Joint Center for Ecological Control of Crop Pests, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
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21
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Izquierdo A, Fahrenberger M, Persampieri T, Benedict MQ, Giles T, Catteruccia F, Emes RD, Dottorini T. Evolution of gene expression levels in the male reproductive organs of Anopheles mosquitoes. Life Sci Alliance 2019; 2:e201800191. [PMID: 30623175 PMCID: PMC6315087 DOI: 10.26508/lsa.201800191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/21/2018] [Accepted: 12/21/2018] [Indexed: 12/31/2022] Open
Abstract
Modifications in gene expression determine many of the phenotypic differentiations between closely related species. This is particularly evident in reproductive tissues, where evolution of genes is more rapid, facilitating the appearance of distinct reproductive characteristics which may lead to species isolation and phenotypic variation. Large-scale, comparative analyses of transcript expression levels have been limited until recently by lack of inter-species data mining solutions. Here, by combining expression normalisation across lineages, multivariate statistical analysis, evolutionary rate, and protein-protein interaction analysis, we investigate ortholog transcripts in the male accessory glands and testes across five closely related species in the Anopheles gambiae complex. We first demonstrate that the differentiation by transcript expression is consistent with the known Anopheles phylogeny. Then, through clustering, we discover groups of transcripts with tissue-dependent expression patterns conserved across lineages, or lineage-dependent patterns conserved across tissues. The strongest associations with reproductive function, transcriptional regulatory networks, protein-protein subnetworks, and evolutionary rate are found for the groups of transcripts featuring large expression differences in lineage or tissue-conserved patterns.
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Affiliation(s)
- Abril Izquierdo
- School of Veterinary Medicine and Science, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK
| | - Martin Fahrenberger
- School of Veterinary Medicine and Science, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK
| | - Tania Persampieri
- Department of Experimental Medicine, University of Perugia, Perugia, Italy
| | - Mark Q Benedict
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Entomology Branch, Atlanta, GA, USA
| | - Tom Giles
- Advanced Data Analysis Centre, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK
| | - Flaminia Catteruccia
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Richard D Emes
- School of Veterinary Medicine and Science, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK.,Advanced Data Analysis Centre, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK
| | - Tania Dottorini
- School of Veterinary Medicine and Science, Sutton Bonington Campus, University of Nottingham, Leicestershire, UK
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22
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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: 5] [Impact Index Per Article: 0.8] [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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23
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Loire E, Tusso S, Caminade P, Severac D, Boursot P, Ganem G, Smadja CM. Do changes in gene expression contribute to sexual isolation and reinforcement in the house mouse? Mol Ecol 2017. [PMID: 28626946 DOI: 10.1111/mec.14212] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Expression divergence, rather than sequence divergence, has been shown to be important in speciation, particularly in the early stages of divergence of traits involved in reproductive isolation. In the two European subspecies of house mice, Mus musculus musculus and Mus musculus domesticus, earlier studies have demonstrated olfactory-based assortative mate preference in populations close to their hybrid zone. It has been suggested that this behaviour evolved following the recent secondary contact between the two taxa (~3,000 years ago) in response to selection against hybridization. To test for a role of changes in gene expression in the observed behavioural shift, we conducted a RNA sequencing experiment on mouse vomeronasal organs. Key candidate genes for pheromone-based subspecies recognition, the vomeronasal receptors, are expressed in these organs. Overall patterns of gene expression varied significantly between samples from the two subspecies, with a large number of differentially expressed genes between the two taxa. In contrast, only ~200 genes were found repeatedly differentially expressed between populations within M. m. musculus that did or did not display assortative mate preferences (close to or more distant from the hybrid zone, respectively), with an overrepresentation of genes belonging to vomeronasal receptor family 2. These receptors are known to play a key role in recognition of chemical cues that handle information about genetic identity. Interestingly, four of five of these differentially expressed receptors belong to the same phylogenetic cluster, suggesting specialization of a group of closely related receptors in the recognition of odorant signals that may allow subspecies recognition and assortative mating.
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Affiliation(s)
- Etienne Loire
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
| | - Sergio Tusso
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
| | - Pierre Caminade
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
| | - Dany Severac
- Montpellier GenomiX (MGX), Institut de Génomique Fonctionnelle, Montpellier Cedex 5, France
| | - Pierre Boursot
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
| | - Guila Ganem
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
| | - Carole M Smadja
- Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de l'Evolution UMR 5554, Institut pour la Recherche et le Développement (IRD), EPHE, Université de Montpellier, Montpellier, France
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24
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Mack KL, Nachman MW. Gene Regulation and Speciation. Trends Genet 2016; 33:68-80. [PMID: 27914620 DOI: 10.1016/j.tig.2016.11.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 11/06/2016] [Accepted: 11/07/2016] [Indexed: 11/17/2022]
Abstract
Understanding the genetic architecture of speciation is a major goal in evolutionary biology. Hybrid dysfunction is thought to arise most commonly through negative interactions between alleles at two or more loci. Divergence between interacting regulatory elements that affect gene expression (i.e., regulatory divergence) may be a common route for these negative interactions to arise. We review here how regulatory divergence between species can result in hybrid dysfunction, including recent theoretical support for this model. We then discuss the empirical evidence for regulatory divergence between species and evaluate evidence for misregulation as a source of hybrid dysfunction. Finally, we review unresolved questions in gene regulation as it pertains to speciation and point to areas that could benefit from future research.
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Affiliation(s)
- Katya L Mack
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
| | - Michael W Nachman
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA.
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25
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Ishishita S, Matsuda Y. Interspecific hybrids of dwarf hamsters and Phasianidae birds as animal models for studying the genetic and developmental basis of hybrid incompatibility. Genes Genet Syst 2016; 91:63-75. [PMID: 27628130 DOI: 10.1266/ggs.16-00022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Hybrid incompatibility is important in speciation as it prevents gene flow between closely related populations. Reduced fitness from hybrid incompatibility may also reinforce prezygotic reproductive isolation between sympatric populations. However, the genetic and developmental basis of hybrid incompatibility in higher vertebrates remains poorly understood. Mammals and birds, both amniotes, have similar developmental processes, but marked differences in development such as the XY/ZW sex determination systems and the presence or absence of genomic imprinting. Here, we review the sterile phenotype of hybrids between the Phodopus dwarf hamsters P. campbelli and P. sungorus, and the inviable phenotype of hybrids between two birds of the family Phasianidae, chicken (Gallus gallus domesticus) and Japanese quail (Coturnix japonica). We propose hypotheses for developmental defects that are associated with these hybrid incompatibilities. In addition, we discuss the genetic and developmental basis for these defects in conjunction with recent findings from mouse and avian models of genetics, reproductive biology and genomics. We suggest that these hybrids are ideal animal models for studying the genetic and developmental basis of hybrid incompatibility in amniotes.
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Affiliation(s)
- Satoshi Ishishita
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University
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26
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Uebbing S, Künstner A, Mäkinen H, Backström N, Bolivar P, Burri R, Dutoit L, Mugal CF, Nater A, Aken B, Flicek P, Martin FJ, Searle SMJ, Ellegren H. Divergence in gene expression within and between two closely related flycatcher species. Mol Ecol 2016; 25:2015-28. [PMID: 26928872 PMCID: PMC4879514 DOI: 10.1111/mec.13596] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 02/15/2016] [Accepted: 02/17/2016] [Indexed: 12/12/2022]
Abstract
Relatively little is known about the character of gene expression evolution as species diverge. It is for instance unclear if gene expression generally evolves in a clock‐like manner (by stabilizing selection or neutral evolution) or if there are frequent episodes of directional selection. To gain insights into the evolutionary divergence of gene expression, we sequenced and compared the transcriptomes of multiple organs from population samples of collared (Ficedula albicollis) and pied flycatchers (F. hypoleuca), two species which diverged less than one million years ago. Ordination analysis separated samples by organ rather than by species. Organs differed in their degrees of expression variance within species and expression divergence between species. Variance was negatively correlated with expression breadth and protein interactivity, suggesting that pleiotropic constraints reduce gene expression variance within species. Variance was correlated with between‐species divergence, consistent with a pattern expected from stabilizing selection and neutral evolution. Using an expression PST approach, we identified genes differentially expressed between species and found 16 genes uniquely expressed in one of the species. For one of these, DPP7, uniquely expressed in collared flycatcher, the absence of expression in pied flycatcher could be associated with a ≈20‐kb deletion including 11 of 13 exons. This study of a young vertebrate speciation model system expands our knowledge of how gene expression evolves as natural populations become reproductively isolated.
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Affiliation(s)
- Severin Uebbing
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Axel Künstner
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Hannu Mäkinen
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Niclas Backström
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Paulina Bolivar
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Reto Burri
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Ludovic Dutoit
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Carina F Mugal
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Alexander Nater
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
| | - Bronwen Aken
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.,Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Fergal J Martin
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK.,Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Stephen M J Searle
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
| | - Hans Ellegren
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden
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Civetta A. Misregulation of Gene Expression and Sterility in Interspecies Hybrids: Causal Links and Alternative Hypotheses. J Mol Evol 2016; 82:176-82. [DOI: 10.1007/s00239-016-9734-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 03/20/2016] [Indexed: 10/22/2022]
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Davis BW, Seabury CM, Brashear WA, Li G, Roelke-Parker M, Murphy WJ. Mechanisms Underlying Mammalian Hybrid Sterility in Two Feline Interspecies Models. Mol Biol Evol 2015; 32:2534-46. [PMID: 26006188 PMCID: PMC4592343 DOI: 10.1093/molbev/msv124] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The phenomenon of male sterility in interspecies hybrids has been observed for over a century, however, few genes influencing this recurrent phenotype have been identified. Genetic investigations have been primarily limited to a small number of model organisms, thus limiting our understanding of the underlying molecular basis of this well-documented "rule of speciation." We utilized two interspecies hybrid cat breeds in a genome-wide association study employing the Illumina 63 K single-nucleotide polymorphism array. Collectively, we identified eight autosomal genes/gene regions underlying associations with hybrid male sterility (HMS) involved in the function of the blood-testis barrier, gamete structural development, and transcriptional regulation. We also identified several candidate hybrid sterility regions on the X chromosome, with most residing in close proximity to complex duplicated regions. Differential gene expression analyses revealed significant chromosome-wide upregulation of X chromosome transcripts in testes of sterile hybrids, which were enriched for genes involved in chromatin regulation of gene expression. Our expression results parallel those reported in Mus hybrids, supporting the "Large X-Effect" in mammalian HMS and the potential epigenetic basis for this phenomenon. These results support the value of the interspecies feline model as a powerful tool for comparison to rodent models of HMS, demonstrating unique aspects and potential commonalities that underpin mammalian reproductive isolation.
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Affiliation(s)
- Brian W Davis
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Christopher M Seabury
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Wesley A Brashear
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
| | - Gang Li
- College of Veterinary Medicine, Texas A&M University
| | - Melody Roelke-Parker
- College of Veterinary Medicine, Texas A&M University National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - William J Murphy
- College of Veterinary Medicine, Texas A&M University Interdisciplinary Program in Genetics, Texas A&M University
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29
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Hybrid male sterility and genome-wide misexpression of male reproductive proteases. Sci Rep 2015; 5:11976. [PMID: 26146165 PMCID: PMC4491705 DOI: 10.1038/srep11976] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/12/2015] [Indexed: 11/16/2022] Open
Abstract
Hybrid male sterility is a common barrier to gene flow between species. Previous studies have posited a link between misregulation of spermatogenesis genes in interspecies hybrids and sterility. However, in the absence of fully fertile control hybrids, it is impossible to differentiate between misregulation associated with sterility vs. fast male gene regulatory evolution. Here, we differentiate between these two possibilities using a D. pseudoobscura species pair that experiences unidirectional hybrid sterility. We identify genes uniquely misexpressed in sterile hybrid male reproductive tracts via RNA-seq. The sterile male hybrids had more misregulated and more over or under expressed genes relative to parental species than the fertile male hybrids. Proteases were the only gene ontology class overrepresented among uniquely misexpressed genes, with four located within a previously identified hybrid male sterility locus. This result highlights the potential role of a previously unexplored class of genes in interspecific hybrid male sterility and speciation.
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Civetta A, Gaudreau C. Hybrid male sterility between Drosophila willistoni species is caused by male failure to transfer sperm during copulation. BMC Evol Biol 2015; 15:75. [PMID: 25925738 PMCID: PMC4415281 DOI: 10.1186/s12862-015-0355-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/21/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The biological concept of species stresses the importance of understanding what mechanisms maintain species reproductively isolated from each other. Often such mechanisms are divided into premating and postmating, with the latest being the result of either prezygotic or postzygotic isolation barriers. Drosophila willistoni quechua and Drosophila willistoni willistoni are two subspecies that experience reproductive isolation. When a D. w. quechua female is crossed with a D. w. willistoni male, the hybrid males (F1QW) are unable to father progeny; however, the reciprocal cross produces fertile hybrids. Thus, the mechanism of isolation is unidirectional hybrid male sterility. However, the sterile F1QW males contain large amounts of motile sperm. Here we explore whether pre-copulatory or post-copulatory pre-zygotic mechanisms serve as major deterrents in the ability of F1QW males to father progeny. RESULTS Comparisons of parental and hybrid males copulation durations showed no significant reduction in copulation duration of F1QW males. Interrupted copulations of the parental species confirmed that sperm transfer occurs before the minimum copulation duration registered for F1QW males. However, we found that when females mate with F1QW males, sperm is not present inside the female storage organs and that the lack of sperm in storage is due to failure to transfer sperm rather than spillage or active sperm dumping by females. CONCLUSIONS Sterility of F1QW hybrid males is primarily driven by their inability to transfer sperm during copulation.
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Affiliation(s)
- Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, Canada.
| | - Chelsea Gaudreau
- Department of Biology, University of Winnipeg, Winnipeg, Canada.
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31
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Barreto FS, Pereira RJ, Burton RS. Hybrid Dysfunction and Physiological Compensation in Gene Expression. Mol Biol Evol 2014; 32:613-22. [DOI: 10.1093/molbev/msu321] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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32
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León-Novelo LG, McIntyre LM, Fear JM, Graze RM. A flexible Bayesian method for detecting allelic imbalance in RNA-seq data. BMC Genomics 2014; 15:920. [PMID: 25339465 PMCID: PMC4230747 DOI: 10.1186/1471-2164-15-920] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 10/09/2014] [Indexed: 01/01/2023] Open
Abstract
Background One method of identifying cis regulatory differences is to analyze allele-specific expression (ASE) and identify cases of allelic imbalance (AI). RNA-seq is the most common way to measure ASE and a binomial test is often applied to determine statistical significance of AI. This implicitly assumes that there is no bias in estimation of AI. However, bias has been found to result from multiple factors including: genome ambiguity, reference quality, the mapping algorithm, and biases in the sequencing process. Two alternative approaches have been developed to handle bias: adjusting for bias using a statistical model and filtering regions of the genome suspected of harboring bias. Existing statistical models which account for bias rely on information from DNA controls, which can be cost prohibitive for large intraspecific studies. In contrast, data filtering is inexpensive and straightforward, but necessarily involves sacrificing a portion of the data. Results Here we propose a flexible Bayesian model for analysis of AI, which accounts for bias and can be implemented without DNA controls. In lieu of DNA controls, this Poisson-Gamma (PG) model uses an estimate of bias from simulations. The proposed model always has a lower type I error rate compared to the binomial test. Consistent with prior studies, bias dramatically affects the type I error rate. All of the tested models are sensitive to misspecification of bias. The closer the estimate of bias is to the true underlying bias, the lower the type I error rate. Correct estimates of bias result in a level alpha test. Conclusions To improve the assessment of AI, some forms of systematic error (e.g., map bias) can be identified using simulation. The resulting estimates of bias can be used to correct for bias in the PG model, without data filtering. Other sources of bias (e.g., unidentified variant calls) can be easily captured by DNA controls, but are missed by common filtering approaches. Consequently, as variant identification improves, the need for DNA controls will be reduced. Filtering does not significantly improve performance and is not recommended, as information is sacrificed without a measurable gain. The PG model developed here performs well when bias is known, or slightly misspecified. The model is flexible and can accommodate differences in experimental design and bias estimation. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-920) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Rita M Graze
- Department of Biological Sciences, Auburn University, 101 Rouse Life Science Building, 36849 Auburn, AL, USA.
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33
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Wei KHC, Clark AG, Barbash DA. Limited gene misregulation is exacerbated by allele-specific upregulation in lethal hybrids between Drosophila melanogaster and Drosophila simulans. Mol Biol Evol 2014; 31:1767-78. [PMID: 24723419 PMCID: PMC4069615 DOI: 10.1093/molbev/msu127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Misregulation of gene expression is often observed in interspecific hybrids and is generally attributed to regulatory incompatibilities caused by divergence between the two genomes. However, it has been challenging to distinguish effects of regulatory divergence from secondary effects including developmental and physiological defects common to hybrids. Here, we use RNA-Seq to profile gene expression in F1 hybrid male larvae from crosses of Drosophila melanogaster to its sibling species D. simulans. We analyze lethal and viable hybrid males, the latter produced using a mutation in the X-linked D. melanogaster Hybrid male rescue (Hmr) gene and compare them with their parental species and to public data sets of gene expression across development. We find that Hmr has drastically different effects on the parental and hybrid genomes, demonstrating that hybrid incompatibility genes can exhibit novel properties in the hybrid genetic background. Additionally, we find that D. melanogaster alleles are preferentially affected between lethal and viable hybrids. We further determine that many of the differences between the hybrids result from developmental delay in the Hmr(+) hybrids. Finally, we find surprisingly modest expression differences in hybrids when compared with the parents, with only 9% and 4% of genes deviating from additivity or expressed outside of the parental range, respectively. Most of these differences can be attributed to developmental delay and differences in tissue types. Overall, our study suggests that hybrid gene misexpression is prone to overestimation and that even between species separated by approximately 2.5 Ma, regulatory incompatibilities are not widespread in hybrids.
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Affiliation(s)
- Kevin H-C Wei
- Department of Molecular Biology and Genetics, Cornell University
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University
| | - Daniel A Barbash
- Department of Molecular Biology and Genetics, Cornell University
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34
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Swain Lenz D, Riles L, Fay JC. Heterochronic meiotic misexpression in an interspecific yeast hybrid. Mol Biol Evol 2014; 31:1333-42. [PMID: 24608322 DOI: 10.1093/molbev/msu098] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Regulatory changes rapidly accumulate between species, and interspecific hybrids often misexpress genes. Hybrid misexpression, expression levels outside the range of both parental species, can result from cis- and trans-acting regulatory changes that interact abnormally in hybrids. Thus, misexpressed genes may contribute to hybrid sterility. However, in the context of a whole organism, misexpression may not result directly from cis-trans interactions but rather indirectly from differences between hybrid and parental abundance of cell types. Here we eliminate the confounding effects of cell types by examining gene expression in a sterile interspecific yeast hybrid during meiosis. We investigated gene expression of the yeasts Saccharomyces cerevisiae, S. paradoxus, and their hybrid at multiple meiotic stages. Although the hybrid and parents exhibit similar changes in expression levels across meiosis, the hybrid meiotic program occurs earlier than either parent. The timing change produces a heterochronic pattern of misexpression during midmeiosis. Coincident with the timing of misexpression, we find a transition from predominantly trans-acting to cis-acting expression divergence and an increase in the number of opposing cis-trans changes. However, we find no direct relationship between opposing cis-trans changes and misexpression. Contrary to the notion that cis-trans interactions cause misexpression, a heterochronic shift in the normal meiotic gene expression program produces patterns of misexpression in an yeast hybrid. Our results imply that temporal dynamics of single cell types is important to understanding hybrid misexpression and its relationship to cis-trans interactions.
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Affiliation(s)
| | - Linda Riles
- Department of Genetics, Washington University
| | - Justin C Fay
- Department of Genetics, Washington UniversityCenter for Genome Sciences and Systems Biology, Washington University
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35
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Coolon JD, McManus CJ, Stevenson KR, Graveley BR, Wittkopp PJ. Tempo and mode of regulatory evolution in Drosophila. Genome Res 2014; 24:797-808. [PMID: 24567308 PMCID: PMC4009609 DOI: 10.1101/gr.163014.113] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Genetic changes affecting gene expression contribute to phenotypic divergence; thus, understanding how regulatory networks controlling gene expression change over time is critical for understanding evolution. Prior studies of expression differences within and between species have identified properties of regulatory divergence, but technical and biological differences among these studies make it difficult to assess the generality of these properties or to understand how regulatory changes accumulate with divergence time. Here, we address these issues by comparing gene expression among strains and species of Drosophila with a range of divergence times and use F1 hybrids to examine inheritance patterns and disentangle cis- and trans-regulatory changes. We find that the fixation of compensatory changes has caused the regulation of gene expression to diverge more rapidly than gene expression itself. Specifically, we observed that the proportion of genes with evidence of cis-regulatory divergence has increased more rapidly with divergence time than the proportion of genes with evidence of expression differences. Surprisingly, the amount of expression divergence explained by cis-regulatory changes did not increase steadily with divergence time, as was previously proposed. Rather, one species (Drosophila sechellia) showed an excess of cis-regulatory divergence that we argue most likely resulted from positive selection in this lineage. Taken together, this work reveals not only the rate at which gene expression evolves, but also the molecular and evolutionary mechanisms responsible for this evolution.
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Affiliation(s)
- Joseph D Coolon
- University of Michigan, Department of Ecology and Evolutionary Biology, Ann Arbor, Michigan 48109, USA
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36
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Abstract
Hybrid dysfunction, a common feature of reproductive barriers between species, is often caused by negative epistasis between loci ("Dobzhansky-Muller incompatibilities"). The nature and complexity of hybrid incompatibilities remain poorly understood because identifying interacting loci that affect complex phenotypes is difficult. With subspecies in the early stages of speciation, an array of genetic tools, and detailed knowledge of reproductive biology, house mice (Mus musculus) provide a model system for dissecting hybrid incompatibilities. Male hybrids between M. musculus subspecies often show reduced fertility. Previous studies identified loci and several X chromosome-autosome interactions that contribute to sterility. To characterize the genetic basis of hybrid sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven 'hotspots,' seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL-but not cis eQTL-were substantially lower when mapping was restricted to a 'fertile' subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. The integrated mapping approach we employed is applicable in a broad range of organisms and we advocate for widespread adoption of a network-centered approach in speciation genetics.
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37
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Morán T, Fontdevila A. Genome-wide dissection of hybrid sterility in Drosophila confirms a polygenic threshold architecture. J Hered 2014; 105:381-96. [PMID: 24489077 DOI: 10.1093/jhered/esu003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To date, different studies about the genetic basis of hybrid male sterility (HMS), a postzygotic reproductive barrier thoroughly investigated using Drosophila species, have demonstrated that no single major gene can produce hybrid sterility without the cooperation of several genetic factors. Early work using hybrids between Drosophila koepferae (Dk) and Drosophila buzzatii (Db) was consistent with the idea that HMS requires the cooperation of several genetic factors, supporting a polygenic threshold (PT) model. Here we present a genome-wide mapping strategy to test the PT model, analyzing serially backcrossed fertile and sterile males in which the Dk genome was introgressed into the Db background. We identified 32 Dk-specific markers significantly associated with hybrid sterility. Our results demonstrate 1) a strong correlation between the number of segregated sterility markers and males' degree of sterility, 2) the exchangeability among markers, 3) their tendency to cluster into low-recombining chromosomal regions, and 4) the requirement for a minimum number (threshold) of markers to elicit sterility. Although our findings do not contradict a role for occasional major hybrid-sterility genes, they conform more to the view that HMS primarily evolves by the cumulative action of many interacting genes of minor effect in a complex PT architecture.
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Affiliation(s)
- Tomás Morán
- the Grup de Biologia Evolutiva, Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
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38
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Wurmser F, Mary-Huard T, Daudin JJ, Joly D, Montchamp-Moreau C. Variation of gene expression associated with colonisation of an anthropized environment: comparison between African and European populations of Drosophila simulans. PLoS One 2013; 8:e79750. [PMID: 24260296 PMCID: PMC3832527 DOI: 10.1371/journal.pone.0079750] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/01/2013] [Indexed: 11/18/2022] Open
Abstract
The comparison of transcriptome profiles among populations is a powerful tool for investigating the role of gene expression change in adaptation to new environments. In this study, we use massively parallel sequencing of 3' cDNAs obtained from large samples of adult males, to compare a population of Drosophila simulans from a natural reserve within its ancestral range (eastern Africa) with a derived population collected in the strongly anthropized Rhône valley (France). The goal was to scan for adaptation linked to the invasion of new environments by the species. Among 15,090 genes retained for the analysis, 794 were found to be differentially expressed between the two populations. We observed an increase in expression of reproduction-related genes in eastern Africa, and an even stronger increase in expression of Cytochrome P450, Glutathione transferase and Glucuronosyl transferase genes in the derived population. These three gene families are involved in detoxification processes, which suggests that pesticides are a major environmental pressure for the species in this area. The survey of the Cyp6g1 upstream region revealed the insertion of a transposable element, Juan, in the regulatory sequence that is almost fixed in the Rhône Valley, but barely present in Mayotte. This shows that Cyp6g1 has undergone parallel evolution in derived populations of D. simulans as previously shown for D. melanogaster. The increasing amount of data produced by comparative population genomics and transcriptomics should permit the identification of additional genes associated with functional divergence among those differentially expressed.
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Affiliation(s)
- François Wurmser
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, and Université Paris-Sud, Orsay, France
| | - Tristan Mary-Huard
- INRA UMR 518 MIA, Paris, France
- AgroParisTech, UMR 518 MIA, Paris, France
- UMR de Génétique Végétale, INRA, Université Paris-sud, CNRS, Gif-sur-Yvette, France
| | | | - Dominique Joly
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, and Université Paris-Sud, Orsay, France
| | - Catherine Montchamp-Moreau
- Laboratoire Évolution Génomes et Spéciation, CNRS UPR9034, Gif-sur-Yvette, and Université Paris-Sud, Orsay, France
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39
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Ferguson J, Gomes S, Civetta A. Rapid male-specific regulatory divergence and down regulation of spermatogenesis genes in Drosophila species hybrids. PLoS One 2013; 8:e61575. [PMID: 23593487 PMCID: PMC3623997 DOI: 10.1371/journal.pone.0061575] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 03/11/2013] [Indexed: 11/19/2022] Open
Abstract
In most crosses between closely related species of Drosophila, the male hybrids are sterile and show postmeiotic abnormalities. A series of gene expression studies using genomic approaches have found significant down regulation of postmeiotic spermatogenesis genes in sterile male hybrids. These results have led some to suggest a direct relationship between down regulation in gene expression and hybrid sterility. An alternative explanation to a cause-and-effect relationship between misregulation of gene expression and male sterility is rapid divergence of male sex regulatory elements leading to incompatible interactions in an interspecies hybrid genome. To test the effect of regulatory divergence in spermatogenesis gene expression, we isolated 35 fertile D. simulans strains with D. mauritiana introgressions in either the X, second or third chromosome. We analyzed gene expression in these fertile hybrid strains for a subset of spermatogenesis genes previously reported as significantly under expressed in sterile hybrids relative to D. simulans. We found that fertile autosomal introgressions can cause levels of gene down regulation similar to that of sterile hybrids. We also found that X chromosome heterospecific introgressions cause significantly less gene down regulation than autosomal introgressions. Our results provide evidence that rapid male sex gene regulatory divergence can explain misexpression of spermatogenesis genes in hybrids.
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Affiliation(s)
- Jennifer Ferguson
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Suzanne Gomes
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada
- * E-mail:
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40
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Nowick K, Carneiro M, Faria R. A prominent role of KRAB-ZNF transcription factors in mammalian speciation? Trends Genet 2012; 29:130-9. [PMID: 23253430 DOI: 10.1016/j.tig.2012.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 11/01/2012] [Accepted: 11/15/2012] [Indexed: 12/29/2022]
Abstract
The mechanisms of speciation have been one of the most debated topics in evolutionary biology. Among all reproductive barriers, postzygotic reproductive isolation is perhaps the one that has attracted the most attention from geneticists. Despite remarkable advances in the identification of loci involved in Drosophila speciation, little is known about the genes, functions, and biochemical interactions of the molecules underlying hybrid sterility and inviability in mammals. Here, we discuss the main evolutionary and molecular features that make transcription factors (TFs), especially the family of zinc finger proteins with a Krüppel-associated box domain (KRAB-ZNF), strong candidates to play an important role in postzygotic reproductive isolation. Motivated by the recent identification of the gene encoding PR domain zinc finger protein 9 (Prdm9; a KRAB-ZNF gene) as the first hybrid sterility gene identified in mammals, we further propose integrative approaches to study KRAB-ZNF genes with the main goal of characterizing the molecular pathways and interactions involved in hybrid incompatibilities.
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Affiliation(s)
- Katja Nowick
- Bioinformatics Group, Department of Computer Science, Interdisciplinary Center for Bioinformatics (IZBI), University of Leipzig, Härtelstrasse 16-18, D-04107 Leipzig, Germany.
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41
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Sex and speciation: Drosophila reproductive tract proteins- twenty five years later. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:191495. [PMID: 23119225 PMCID: PMC3483712 DOI: 10.1155/2012/191495] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 09/16/2012] [Indexed: 11/20/2022]
Abstract
The protein electrophoresis revolution, nearly fifty years ago, provided the first glimpse into the nature of molecular genetic variation within and between species and showed that the amount of genetic differences between newly arisen species was minimal. Twenty years later, 2D electrophoresis showed that, in contrast to general gene-enzyme variation, reproductive tract proteins were less polymorphic within species but highly diverged between species. The 2D results were interesting and revolutionary, but somewhat uninterpretable because, at the time, rapid evolution and selective sweeps were not yet part of the common vocabulary of evolutionary biologists. Since then, genomic studies of sex and reproduction-related (SRR) genes have grown rapidly into a large area of research in evolutionary biology and are shedding light on a number of phenomena. Here we review some of the major and current fields of research that have greatly contributed to our understanding of the evolutionary dynamics and importance of SRR genes and genetic systems in understanding reproductive biology and speciation.
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Diz AP, Dudley E, Skibinski DOF. Identification and characterization of highly expressed proteins in sperm cells of the marine mussel Mytilus edulis. Proteomics 2012; 12:1949-56. [PMID: 22623270 DOI: 10.1002/pmic.201100500] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Proteomic analysis on sperm has been restricted to only a few model organisms. We present here a 2DE PAGE proteome map of sperm cells from a nonmodel organism, the marine mussel Mytilus edulis, a free-spawning marine invertebrate with external fertilization. Ninety-six protein spots showing high expression were selected and of these 77 were successfully identified by nESI-MS analysis. Many of the identifications are relevant to sperm cell physiology and mtDNA functioning. The results and proteomics approach used are discussed in relation to their potential for advancing understanding of the unusual system of mtDNA inheritance described in Mytilus spp., and for the testing of evolutionary hypotheses pertaining to the role of fertilization in the speciation process.
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Affiliation(s)
- Angel P Diz
- Department of Biochemistry, Genetics and Immunology, Faculty of Biology, University of Vigo, Vigo, Spain.
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Hunt BG, Ometto L, Keller L, Goodisman MAD. Evolution at two levels in fire ants: the relationship between patterns of gene expression and protein sequence evolution. Mol Biol Evol 2012; 30:263-71. [PMID: 23051842 DOI: 10.1093/molbev/mss234] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Variation in protein sequence and gene expression each contribute to phenotypic diversity, and may be subject to similar selective pressures. Eusocial insects are particularly useful for investigating the evolutionary link between protein sequence and condition-dependent patterns of gene expression because gene expression plays a central role in determining differences between eusocial insect sexes and castes. We investigated the relationship between protein coding sequence evolution and gene expression patterns in the fire ants Solenopsis invicta, S. richteri, and their hybrids to gain greater insight into how selection jointly operates on gene expression and coding sequence. We found that genes with high expression variability within castes and sexes were frequently differentially expressed between castes and sexes, as well as between species and hybrids. These results indicate that genes showing high variation in expression in one context also tend to show high variation in expression in other contexts. Our analyses further revealed that variation in both intra- and interspecific gene expression was positively associated with rate of protein sequence evolution in Solenopsis. This suggests that selective constraints on a gene operate both at the level of protein sequence and at the level of gene expression regulation. Overall, our study provides one of the strongest demonstrations that selective constraints mediate both protein sequence evolution and gene expression variability across different biological contexts and timescales.
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Affiliation(s)
- Brendan G Hunt
- School of Biology, Georgia Institute of Technology, USA.
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Coevolution within and between regulatory loci can preserve promoter function despite evolutionary rate acceleration. PLoS Genet 2012; 8:e1002961. [PMID: 23028368 PMCID: PMC3447958 DOI: 10.1371/journal.pgen.1002961] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 08/06/2012] [Indexed: 11/19/2022] Open
Abstract
Phenotypes that appear to be conserved could be maintained not only by strong purifying selection on the underlying genetic systems, but also by stabilizing selection acting via compensatory mutations with balanced effects. Such coevolution has been invoked to explain experimental results, but has rarely been the focus of study. Conserved expression driven by the unc-47 promoters of Caenorhabditis elegans and C. briggsae persists despite divergence within a cis-regulatory element and between this element and the trans-regulatory environment. Compensatory changes in cis and trans are revealed when these promoters are used to drive expression in the other species. Functional changes in the C. briggsae promoter, which has experienced accelerated sequence evolution, did not lead to alteration of gene expression in its endogenous environment. Coevolution among promoter elements suggests that complex epistatic interactions within cis-regulatory elements may facilitate their divergence. Our results offer a detailed picture of regulatory evolution in which subtle, lineage-specific, and compensatory modifications of interacting cis and trans regulators together maintain conserved gene expression patterns. Some phenotypes, including gene expression patterns, are conserved between distantly related species. However, the molecular bases of those phenotypes are not necessarily conserved. Instead, regulatory DNA sequences and the proteins with which they interact can change over time with balanced effects, preserving expression patterns and concealing regulatory divergence. Coevolution between interacting molecules makes gene regulation highly species-specific, and it can be detected when the cis-regulatory DNA of one species is used to drive expression in another species. In this way, we identified regions of the C. elegans and C. briggsae unc-47 promoters that have coevolved with the lineage-specific trans-regulatory environments of these organisms. The C. briggsae promoter experienced accelerated sequence change relative to related species. All of this evolution occurred without changing the expression pattern driven by the promoter in its endogenous environment.
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Llopart A. The Rapid Evolution of X-linked Male-Biased Gene Expression and the Large-X Effect in Drosophila yakuba, D. santomea, and Their Hybrids. Mol Biol Evol 2012; 29:3873-86. [DOI: 10.1093/molbev/mss190] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Johnson NA, Lachance J. The genetics of sex chromosomes: evolution and implications for hybrid incompatibility. Ann N Y Acad Sci 2012; 1256:E1-22. [PMID: 23025408 PMCID: PMC3509754 DOI: 10.1111/j.1749-6632.2012.06748.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Heteromorphic sex chromosomes, where one sex has two different types of sex chromosomes, face very different evolutionary consequences than do autosomes. Two important features of sex chromosomes arise from being present in only one copy in one of the sexes: dosage compensation and the meiotic silencing of sex chromosomes. Other differences arise because sex chromosomes spend unequal amounts of time in each sex. Thus, the impact of evolutionary processes (mutation, selection, genetic drift, and meiotic drive) differs substantially between each sex chromosome, and between the sex chromosomes and the autosomes. Sex chromosomes also play a disproportionate role in Haldane's rule and other important patterns related to hybrid incompatibility, and thus speciation. We review the consequences of sex chromosomes on hybrid incompatibility. A theme running through this review is that epigenetic processes, notably those related to chromatin, may be more important to the evolution of sex chromosomes and the evolution of hybrid incompatibility than previously recognized.
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Affiliation(s)
- Norman A Johnson
- Department of Plant, Soil, and Insect Sciences, and Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA.
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OMETTO LINO, ROSS KENNETHG, SHOEMAKER D, KELLER LAURENT. Disruption of gene expression in hybrids of the fire antsSolenopsis invictaandSolenopsis richteri. Mol Ecol 2012; 21:2488-501. [DOI: 10.1111/j.1365-294x.2012.05544.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Ephemeral association between gene CG5762 and hybrid male sterility in Drosophila sibling species. J Mol Evol 2011; 73:181-7. [PMID: 22052252 DOI: 10.1007/s00239-011-9466-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 10/05/2011] [Indexed: 01/14/2023]
Abstract
Interspecies divergence in regulatory pathways may result in hybrid male sterility (HMS) when dominance and epistatic interactions between alleles that are functional within one genome are disrupted in hybrid genomes. The identification of genes contributing to HMS and other hybrid dysfunctions is essential for understanding the origin of new species (speciation). Previously, we identified a panel of male-specific loci misexpressed in sterile male hybrids of Drosophila simulans and D. mauritiana relative to parental species. In the current work, we attempt to dissect the genetic associations between HMS and one of the genes, CG5762, a Drosophila-unique locus characterized by rapid sequence divergence within the genus, presumably driven by positive natural selection. CG5762 is underexpressed in sterile backcross males compared with their fertile brothers. In CG5762 heterozygotes, the D. mauritiana allele is consistently overexpressed on both the D. simulans and D. mauritiana backcross genomic background, suggesting a cis-acting regulation factor. There is a significant association between heterozygosity and HMS in hybrid males from early but not later backcross generations. Microsatellite markers spanning CG5762 fail to associate with HMS. These observations lead to a conclusion that CG5762 is not a causative factor of HMS. Although genetic linkage between CG5762 and a neighboring causative introgression cannot be ruled out, it seems that the pattern is most consistent with CG5762 participating in epistatic interactions that are disrupted in flies with HMS.
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MAYROSE MAYA, KANE NOLANC, MAYROSE ITAY, DLUGOSCH KATRINAM, RIESEBERG LORENH. Increased growth in sunflower correlates with reduced defences and altered gene expression in response to biotic and abiotic stress. Mol Ecol 2011; 20:4683-94. [DOI: 10.1111/j.1365-294x.2011.05301.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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