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Li Z, Xue AZ, Maeda GP, Li Y, Nabity PD, Moran NA. Phylloxera and Aphids Show Distinct Features of Genome Evolution Despite Similar Reproductive Modes. Mol Biol Evol 2023; 40:msad271. [PMID: 38069672 DOI: 10.1093/molbev/msad271] [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: 08/19/2023] [Revised: 11/06/2023] [Accepted: 12/05/2023] [Indexed: 12/19/2023] Open
Abstract
Genomes of aphids (family Aphididae) show several unusual evolutionary patterns. In particular, within the XO sex determination system of aphids, the X chromosome exhibits a lower rate of interchromosomal rearrangements, fewer highly expressed genes, and faster evolution at nonsynonymous sites compared with the autosomes. In contrast, other hemipteran lineages have similar rates of interchromosomal rearrangement for autosomes and X chromosomes. One possible explanation for these differences is the aphid's life cycle of cyclical parthenogenesis, where multiple asexual generations alternate with 1 sexual generation. If true, we should see similar features in the genomes of Phylloxeridae, an outgroup of aphids which also undergoes cyclical parthenogenesis. To investigate this, we generated a chromosome-level assembly for the grape phylloxera, an agriculturally important species of Phylloxeridae, and identified its single X chromosome. We then performed synteny analysis using the phylloxerid genome and 30 high-quality genomes of aphids and other hemipteran species. Unexpectedly, we found that the phylloxera does not share aphids' patterns of chromosome evolution. By estimating interchromosomal rearrangement rates on an absolute time scale, we found that rates are elevated for aphid autosomes compared with their X chromosomes, but this pattern does not extend to the phylloxera branch. Potentially, the conservation of X chromosome gene content is due to selection on XO males that appear in the sexual generation. We also examined gene duplication patterns across Hemiptera and uncovered horizontal gene transfer events contributing to phylloxera evolution.
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Affiliation(s)
- Zheng Li
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Allen Z Xue
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Gerald P Maeda
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yiyuan Li
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
- Institute of Plant Virology, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Paul D Nabity
- Department of Botany and Plant Sciences, University of California Riverside, Riverside, CA 92521, USA
| | - Nancy A Moran
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
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Li Z, Xue AZ, Maeda GP, Li Y, Nabity PD, Moran NA. Phylloxera and aphids show distinct features of genome evolution despite similar reproductive modes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555181. [PMID: 37693541 PMCID: PMC10491136 DOI: 10.1101/2023.08.28.555181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Genomes of aphids (family Aphididae) show several unusual evolutionary patterns. In particular, within the XO sex determination system of aphids, the X chromosome exhibits a lower rate of interchromosomal rearrangements, fewer highly expressed genes, and faster evolution at nonsynonymous sites compared to the autosomes. In contrast, other hemipteran lineages have similar rates of interchromosomal rearrangement for autosomes and X chromosomes. One possible explanation for these differences is the aphid's life cycle of cyclical parthenogenesis, where multiple asexual generations alternate with one sexual generation. If true, we should see similar features in the genomes of Phylloxeridae, an outgroup of aphids which also undergoes cyclical parthenogenesis. To investigate this, we generated a chromosome-level assembly for the grape phylloxera, an agriculturally important species of Phylloxeridae, and identified its single X chromosome. We then performed synteny analysis using the phylloxerid genome and 30 high-quality genomes of aphids and other hemipteran species. Unexpectedly, we found that the phylloxera does not share aphids' patterns of chromosome evolution. By estimating interchromosomal rearrangement rates on an absolute time scale, we found that rates are elevated for aphid autosomes compared to their X chromosomes, but this pattern does not extend to the phylloxera branch. Potentially, the conservation of X chromosome gene content is due to selection on XO males that appear in the sexual generation. We also examined gene duplication patterns across Hemiptera and uncovered horizontal gene transfer events contributing to phylloxera evolution.
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Mathers TC, Wouters RHM, Mugford ST, Biello R, van Oosterhout C, Hogenhout SA. Hybridisation has shaped a recent radiation of grass-feeding aphids. BMC Biol 2023; 21:157. [PMID: 37443008 PMCID: PMC10347838 DOI: 10.1186/s12915-023-01649-4] [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: 12/19/2022] [Accepted: 06/13/2023] [Indexed: 07/15/2023] Open
Abstract
BACKGROUND Aphids are common crop pests. These insects reproduce by facultative parthenogenesis involving several rounds of clonal reproduction interspersed with an occasional sexual cycle. Furthermore, clonal aphids give birth to live young that are already pregnant. These qualities enable rapid population growth and have facilitated the colonisation of crops globally. In several cases, so-called "super clones" have come to dominate agricultural systems. However, the extent to which the sexual stage of the aphid life cycle has shaped global pest populations has remained unclear, as have the origins of successful lineages. Here, we used chromosome-scale genome assemblies to disentangle the evolution of two global pests of cereals-the English (Sitobion avenae) and Indian (Sitobion miscanthi) grain aphids. RESULTS Genome-wide divergence between S. avenae and S. miscanthi is low. Moreover, comparison of haplotype-resolved assemblies revealed that the S. miscanthi isolate used for genome sequencing is likely a hybrid, with one of its diploid genome copies closely related to S. avenae (~ 0.5% divergence) and the other substantially more divergent (> 1%). Population genomics analyses of UK and China grain aphids showed that S. avenae and S. miscanthi are part of a cryptic species complex with many highly differentiated lineages that predate the origins of agriculture. The complex consists of hybrid lineages that display a tangled history of hybridisation and genetic introgression. CONCLUSIONS Our analyses reveal that hybridisation has substantially contributed to grain aphid diversity, and hence, to the evolutionary potential of this important pest species. Furthermore, we propose that aphids are particularly well placed to exploit hybridisation events via the rapid propagation of live-born "frozen hybrids" via asexual reproduction, increasing the likelihood of hybrid lineage formation.
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Affiliation(s)
- Thomas C Mathers
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK.
- Tree of Life, Welcome Sanger Institute, Hinxton, Cambridge, UK.
| | - Roland H M Wouters
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Sam T Mugford
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Roberto Biello
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK
| | | | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, UK.
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Defendini H, Rimbault M, Mahéo F, Cloteau R, Denis G, Mieuzet L, Outreman Y, Simon JC, Jaquiéry J. Evolutionary consequences of loss of sexual reproduction on male-related traits in parthenogenetic lineages of the pea aphid. Mol Ecol 2023; 32:3672-3685. [PMID: 37143321 DOI: 10.1111/mec.16961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/03/2023] [Accepted: 04/05/2023] [Indexed: 05/06/2023]
Abstract
Transition from sexual reproduction to parthenogenesis constitutes a major life-history change with deep evolutionary consequences for sex-related traits, which are expected to decay. The pea aphid Acyrthosiphon pisum shows intraspecific reproductive polymorphism, with cold-resistant cyclically parthenogenetic (CP) lineages that alternate sexual and asexual generations and cold-sensitive obligately parthenogenetic (OP) lineages that produce only asexual females but still males. Here, the genotyping of 219 pea aphid lineages collected in cold-winter and mild-winter regions revealed contrasting population structures. Samples from cold-winter regions consisted mostly of distinct multilocus genotypes (MLGs) usually represented by a single sample (101 different MLGs for 111 samples) and were all phenotyped as CP. In contrast, fewer MLGs were found in mild-winter regions (28 MLGs for 108 samples), all but one being OP. Since the males produced by OP lineages are unlikely to pass on their genes (sexual females being rare in mild-winter regions), we tested the hypothesis that their traits could degenerate due to lack of selection by comparing male production and male reproductive success between OP and CP lineages. Male production was indeed reduced in OP lineages, but a less clear pattern was observed for male reproductive success: females mated with OP males laid fewer eggs (fertilized or not) but OP and CP males fertilized the same proportion of eggs. These differences may stem from the type of selective forces: male production may be counter-selected whereas male performances may evolve under the slower process of relaxed selection. The overall effective reproductive capacity of OP males could result from recent sex loss in OP lineages or underestimated reproductive opportunities.
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Affiliation(s)
- Hélène Defendini
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Maud Rimbault
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Frédérique Mahéo
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Romuald Cloteau
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Gaëtan Denis
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Lucie Mieuzet
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
| | - Yannick Outreman
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Rennes, France
| | | | - Julie Jaquiéry
- UMR 1349 IGEPP, INRAE, Institut Agro, Université Rennes 1, Le Rheu, France
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Pacheco ID, Walling LL, Atkinson PW. Gene Editing and Genetic Control of Hemipteran Pests: Progress, Challenges and Perspectives. Front Bioeng Biotechnol 2022; 10:900785. [PMID: 35747496 PMCID: PMC9209771 DOI: 10.3389/fbioe.2022.900785] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/09/2022] [Indexed: 12/16/2022] Open
Abstract
The origin of the order Hemiptera can be traced to the late Permian Period more than 230 MYA, well before the origin of flowering plants 100 MY later in during the Cretaceous period. Hemipteran species consume their liquid diets using a sucking proboscis; for phytophagous hemipterans their mouthparts (stylets) are elegant structures that enable voracious feeding from plant xylem or phloem. This adaptation has resulted in some hemipteran species becoming globally significant pests of agriculture resulting in significant annual crop losses. Due to the reliance on chemical insecticides for the control of insect pests in agricultural settings, many hemipteran pests have evolved resistance to insecticides resulting in an urgent need to develop new, species-specific and environmentally friendly methods of pest control. The rapid advances in CRISPR/Cas9 technologies in model insects such as Drosophila melanogaster, Tribolium castaneum, Bombyx mori, and Aedes aegypti has spurred a new round of innovative genetic control strategies in the Diptera and Lepidoptera and an increased interest in assessing genetic control technologies for the Hemiptera. Genetic control approaches in the Hemiptera have, to date, been largely overlooked due to the problems of introducing genetic material into the germline of these insects. The high frequency of CRISPR-mediated mutagenesis in model insect species suggest that, if the delivery problem for Hemiptera could be solved, then gene editing in the Hemiptera might be quickly achieved. Significant advances in CRISPR/Cas9 editing have been realized in nine species of Hemiptera over the past 4 years. Here we review progress in the Hemiptera and discuss the challenges and opportunities for extending contemporary genetic control strategies into species in this agriculturally important insect orderr.
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Affiliation(s)
- Inaiara D. Pacheco
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
| | - Linda L. Walling
- Department of Botany & Plant Sciences, University of California, Riverside, Riverside, CA, United States
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, United States
| | - Peter W. Atkinson
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
- Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA, United States
- *Correspondence: Peter W. Atkinson,
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Detection of sex in adults and larvae of Leptinotarsa decemlineata on principle of copy number variation. Sci Rep 2022; 12:4602. [PMID: 35301399 PMCID: PMC8931150 DOI: 10.1038/s41598-022-08642-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/10/2022] [Indexed: 12/02/2022] Open
Abstract
The identification of sex in larvae of insects is usually challenging or even impossible, while in adults the sexual dimorphism is usually evident. Here, we used copy number analysis to develop a method of sex detection in Colorado potato beetle (Leptinotarsa decemlineata), which has an X0 sex determination system. The X linked gene LdVssc and autosomal gene LdUBE3B were identified as appropriate target and reference loci, respectively. The copy numbers (CNV) of LdVssc in males and females were estimated using standard droplet digital PCR (ddPCR) and real-time PCR (qPCR). With both methods, CNVs were bimodally distributed (BAddPCR = 0.709 and BAqPCR = 0.683) with 100% ability to distinguish females from males. The use of qPCR-based sex detection in a broad collection of 448 random CPB adults showed a perfect association (Phi = 1.0, p < 0.05) with the true sexes of adults, with mean CNV in females of 2.032 (SD = 0.227) and 0.989 in males (SD = 0.147). In the collection of 50 random 4th instar larvae, 27 females and 23 males were identified, consistent with the expected 1:1 sex ratio (p = 0.689). The method is suitable for sexing in all stages of ontogenesis. The optimal cost-effective application of the method in large populations requires the DNA extraction using CTAB, the qPCR assay in one biological replicate and three technical replicates of each marker, and the use of one randomly chosen male per run to calibrate calculation of CNV.
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Kuznetsova VG, Gavrilov-Zimin IA, Grozeva SM, Golub NV. Comparative analysis of chromosome numbers and sex chromosome systems in Paraneoptera (Insecta). COMPARATIVE CYTOGENETICS 2021; 15:279-327. [PMID: 34616525 PMCID: PMC8490342 DOI: 10.3897/compcytogen.v15.i3.71866] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/06/2021] [Indexed: 05/28/2023]
Abstract
This article is part (the 4th article) of the themed issue (a monograph) "Aberrant cytogenetic and reproductive patterns in the evolution of Paraneoptera". The purpose of this article is to consider chromosome structure and evolution, chromosome numbers and sex chromosome systems, which all together constitute the chromosomal basis of reproduction and are essential for reproductive success. We are based on our own observations and literature data available for all major lineages of Paraneoptera including Zoraptera (angel insects), Copeognatha (=Psocoptera; bark lice), Parasita (=Phthiraptera s. str; true lice), Thysanoptera (thrips), Homoptera (scale insects, aphids, jumping plant-lice, whiteflies, and true hoppers), Heteroptera (true bugs), and Coleorrhyncha (moss bugs). Terminology, nomenclature, classification, and the study methods are given in the first paper of the issue (Gavrilov-Zimin et al. 2021).
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Affiliation(s)
- Valentina G. Kuznetsova
- Zoological Institute, Russian Academy of Sciences, Universitetskaya emb. 1, St. Petersburg, 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
| | - Ilya A. Gavrilov-Zimin
- Zoological Institute, Russian Academy of Sciences, Universitetskaya emb. 1, St. Petersburg, 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
| | - Snejana M. Grozeva
- Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Blvd Tsar Osvoboditel 1, Sofia 1000, BulgariaInstitute of Biodiversity and Ecosystem Research, Bulgarian Academy of SciencesSofiaBulgaria
| | - Natalia V. Golub
- Zoological Institute, Russian Academy of Sciences, Universitetskaya emb. 1, St. Petersburg, 199034, RussiaZoological Institute, Russian Academy of SciencesSt. PetersburgRussia
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Inbreeding, male viability, and the remarkable evolutionary stability of the aphid X chromosome. Heredity (Edinb) 2021; 127:135-140. [PMID: 33993199 PMCID: PMC8322266 DOI: 10.1038/s41437-021-00440-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 02/03/2023] Open
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Cornetti L, Ebert D. No evidence for genetic sex determination in Daphnia magna. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202292. [PMID: 34150315 PMCID: PMC8206689 DOI: 10.1098/rsos.202292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/18/2021] [Indexed: 06/12/2023]
Abstract
Mechanisms of sex determination (SD) differ widely across the tree of life. In genotypic sex determination (GSD), genetic elements determine whether individuals are male or female, while in environmental sex determination (ESD), external cues control the sex of the offspring. In cyclical parthenogens, females produce mostly asexual daughters, but environmental stimuli such as crowding, temperature or photoperiod may cause them to produce sons. In aphids, sons are induced by ESD, even though GSD is present, with females carrying two X chromosomes and males only one (X0 SD system). By contrast, although ESD exists in Daphnia, the two sexes were suggested to be genetically identical, based on a 1972 study on Daphnia magna (2n=20) that used three allozyme markers. This study cannot, however, rule out an X0 system, as all three markers may be located on autosomes. Motivated by the life cycle similarities of Daphnia and aphids, and the absence of karyotype information for Daphnia males, we tested for GSD (homomorphic sex chromosomes and X0) systems in D. magna using a whole-genome approach by comparing males and females of three genotypes. Our results confirm the absence of haploid chromosomes or haploid genomic regions in D. magna males as well as the absence of sex-linked genomic regions and sex-specific single-nucleotide polymorphisms. Within the limitations of the three studied populations here and the methods used, we suggest that our results make the possibility of genetic differences among sexes in the widely used Daphnia model system very unlikely.
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Affiliation(s)
- Luca Cornetti
- Department of Environmental Sciences, Zoology, University of Basel, 4051, Basel, Switzerland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, 4051, Basel, Switzerland
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10
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Male-Biased microRNA Discovery in the Pea Aphid. INSECTS 2021; 12:insects12060533. [PMID: 34201015 PMCID: PMC8228725 DOI: 10.3390/insects12060533] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/28/2021] [Accepted: 06/01/2021] [Indexed: 12/18/2022]
Abstract
Epigenetic mechanisms modulate gene expression levels during development, shaping how a single genome produces a diversity of phenotypes. Here, we begin to explore the epigenetic regulation of sexual dimorphism in pea aphids (Acyrthosiphon pisum) by focusing on microRNAs. Previous analyses of microRNAs in aphids have focused solely on females, so we performed deep sequencing of a sample containing early-stage males. We used this sample, plus samples from Genbank, to find 207 novel pea aphid microRNA coding loci. We localized microRNA loci to a chromosome-level assembly of the pea aphid genome and found that those on the X chromosome have lower overall expression compared to those on autosomes. We then identified a set of 19 putative male-biased microRNAs and found them enriched on the X chromosome. Finally, we performed protein-coding RNA-Seq of first instar female and male pea aphids to identify genes with lower expression in males. 10 of these genes were predicted targets of the 19 male-biased microRNAs. Our study provides the most complete set of microRNAs in the pea aphid to date and serves as foundational work for future studies on the epigenetic control of sexual dimorphism.
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Li Y, Zhang B, Moran NA. The Aphid X Chromosome Is a Dangerous Place for Functionally Important Genes: Diverse Evolution of Hemipteran Genomes Based on Chromosome-Level Assemblies. Mol Biol Evol 2021; 37:2357-2368. [PMID: 32289166 PMCID: PMC7403619 DOI: 10.1093/molbev/msaa095] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Different evolutionary forces shape gene content and sequence evolution on autosomes versus sex chromosomes. Location on a sex chromosome can favor male-beneficial or female-beneficial mutations depending on the sex determination system and selective pressure on different sexual morphs. An X0 sex determination can lead to autosomal enrichment of male-biased genes, as observed in some hemipteran insect species. Aphids share X0 sex determination; however, models predict the opposite pattern, due to their unusual life cycles, which alternate between all-female asexual generations and a single sexual generation. Predictions include enrichment of female-biased genes on autosomes and of male-biased genes on the X, in contrast to expectations for obligately sexual species. Robust tests of these models require chromosome-level genome assemblies for aphids and related hemipterans with X0 sex determination and obligate sexual reproduction. In this study, we built the first chromosome-level assembly of a psyllid, an aphid relative with X0 sex determination and obligate sexuality, and compared it with recently resolved chromosome-level assemblies of aphid genomes. Aphid and psyllid X chromosomes differ strikingly. In aphids, female-biased genes are strongly enriched on autosomes and male-biased genes are enriched on the X. In psyllids, male-biased genes are enriched on autosomes. Furthermore, functionally important gene categories of aphids are enriched on autosomes. Aphid X-linked genes and male-biased genes are under relaxed purifying selection, but gene content and order on the X is highly conserved, possibly reflecting constraints imposed by unique chromosomal mechanisms associated with the unusual aphid life cycle.
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Affiliation(s)
- Yiyuan Li
- Department of Integrative Biology, University of Texas at Austin, Austin, TX
| | - Bo Zhang
- Department of Integrative Biology, University of Texas at Austin, Austin, TX.,Laboratory of Predatory Mites, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
| | - Nancy A Moran
- Department of Integrative Biology, University of Texas at Austin, Austin, TX
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12
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Mathers TC, Wouters RHM, Mugford ST, Swarbreck D, van Oosterhout C, Hogenhout SA. Chromosome-Scale Genome Assemblies of Aphids Reveal Extensively Rearranged Autosomes and Long-Term Conservation of the X Chromosome. Mol Biol Evol 2021; 38:856-875. [PMID: 32966576 PMCID: PMC7947777 DOI: 10.1093/molbev/msaa246] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chromosome rearrangements are arguably the most dramatic type of mutations, often leading to rapid evolution and speciation. However, chromosome dynamics have only been studied at the sequence level in a small number of model systems. In insects, Diptera and Lepidoptera have conserved genome structure at the scale of whole chromosomes or chromosome arms. Whether this reflects the diversity of insect genome evolution is questionable given that many species exhibit rapid karyotype evolution. Here, we investigate chromosome evolution in aphids-an important group of hemipteran plant pests-using newly generated chromosome-scale genome assemblies of the green peach aphid (Myzus persicae) and the pea aphid (Acyrthosiphon pisum), and a previously published assembly of the corn-leaf aphid (Rhopalosiphum maidis). We find that aphid autosomes have undergone dramatic reorganization over the last 30 My, to the extent that chromosome homology cannot be determined between aphids from the tribes Macrosiphini (Myzus persicae and Acyrthosiphon pisum) and Aphidini (Rhopalosiphum maidis). In contrast, gene content of the aphid sex (X) chromosome remained unchanged despite rapid sequence evolution, low gene expression, and high transposable element load. To test whether rapid evolution of genome structure is a hallmark of Hemiptera, we compared our aphid assemblies with chromosome-scale assemblies of two blood-feeding Hemiptera (Rhodnius prolixus and Triatoma rubrofasciata). Despite being more diverged, the blood-feeding hemipterans have conserved synteny. The exceptional rate of structural evolution of aphid autosomes renders them an important emerging model system for studying the role of large-scale genome rearrangements in evolution.
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Affiliation(s)
- Thomas C Mathers
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Roland H M Wouters
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Sam T Mugford
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - David Swarbreck
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - Cock van Oosterhout
- School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
| | - Saskia A Hogenhout
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, United Kingdom
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13
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Mandrioli M, Melchiori G, Panini M, Chiesa O, Giordano R, Mazzoni E, Manicardi GC. Analysis of the extent of synteny and conservation in the gene order in aphids: A first glimpse from the Aphis glycines genome. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 113:103228. [PMID: 31446034 DOI: 10.1016/j.ibmb.2019.103228] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 07/03/2019] [Accepted: 08/21/2019] [Indexed: 06/10/2023]
Abstract
In the last decade several insect genomes have been sequenced, but for most the chromosomal mapping of the identified scaffolds/annotated genes is not available. The lack of this information makes it difficult to analyse various genetic aspects, including the presence of genome rearrangements and the extent of synteny within and across species. We mapped five multigenic DNA families (major and minor rDNAs, histone gene cluster, esterases and carotenoid desaturases) and seven scaffolds corresponding to 9 Mb of the soybean aphid, Aphis glycines, genome and identified loci spanning the four soybean aphid chromosomes. A comparative analysis of the localization of the annotated A. glycines genes with respect to the peach potato aphid, Myzus persicae, and the fly, Drosophila melanogaster, evidenced a lower degree of synteny between the two aphid species than in the aphid-fly comparison. Only 1.4 genes per syntenic block were observed in aphids in contrast to 2.3 genes per block in flies. This higher chromosomal rearrangement rate in aphids could be explained considering that they possess holocentric chromosomes that can favour the stabilization and inheritance of chromosomal rearrangements. Lastly, our experiments did not detect the presence of chimeric assemblies in the newly available A. glycines biotype 1 genome, differently from what reported in assembled genome of other aphid species, suggesting that chromosomal mapping can be used to ascertain the quality of assembled genomes.
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Affiliation(s)
- Mauro Mandrioli
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125, Modena, Italy.
| | - Giulia Melchiori
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125, Modena, Italy
| | - Michela Panini
- Dipartimento di Scienze delle produzioni vegetali sostenibili, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Olga Chiesa
- Dipartimento di Scienze delle produzioni vegetali sostenibili, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Rosanna Giordano
- Puerto Rico Science, Technology & Research Trust, San Juan, PR, USA; Know Your Bee, Inc., San Juan, PR, USA
| | - Emanuele Mazzoni
- Dipartimento di Scienze delle produzioni vegetali sostenibili, Università Cattolica del Sacro Cuore, Piacenza, Italy
| | - Gian Carlo Manicardi
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via Campi 213/D, 41125, Modena, Italy
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14
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Bechsgaard J, Schou MF, Vanthournout B, Hendrickx F, Knudsen B, Settepani V, Schierup MH, Bilde T. Evidence for Faster X Chromosome Evolution in Spiders. Mol Biol Evol 2019; 36:1281-1293. [PMID: 30912801 PMCID: PMC6526907 DOI: 10.1093/molbev/msz074] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both species. X chromosome-to-autosome diversity (piX/piA) ratios were estimated in multiple populations. The average piX/piA estimates of S. africanus (0.57 [95% CI: 0.55-0.60]) was lower than the neutral expectation of 0.75, consistent with more hitchhiking events on X-linked loci and/or a lower X chromosome mutation rate, and we provide evidence in support of both. The social species S. mimosarum has a significantly higher piX/piA ratio (0.72 [95% CI: 0.65-0.79]) in agreement with its female-biased sex ratio. Stegodyphus mimosarum also have different piX/piA estimates among populations, which we interpret as evidence for recurrent founder events. Simulations show that recurrent founder events are expected to decrease the piX/piA estimates in S. mimosarum, thus underestimating the true effect of female-biased sex ratios. Finally, we found lower synonymous divergence on X chromosomes in both species, and the male-to-female substitution ratio to be higher than 1, indicating a higher mutation rate in males.
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Affiliation(s)
| | - Mads Fristrup Schou
- Department of Bioscience, Aarhus University, Aarhus C, Denmark.,Department of Biology, Lund University, SE-223 62 Lund, Sweden
| | - Bram Vanthournout
- Department of Bioscience, Aarhus University, Aarhus C, Denmark.,Evolution and Optics of Nanostructure Group (EON), Biology Department, Ghent University, Ghent, Belgium
| | - Frederik Hendrickx
- Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Terrestrial Ecology Unit (TEREC), Biology Department, Ghent University, Ghent, Belgium
| | | | | | - Mikkel Heide Schierup
- Department of Bioscience, Aarhus University, Aarhus C, Denmark.,Bioinformatics Research Centre (BiRC), Aarhus University, Aarhus C, Denmark
| | - Trine Bilde
- Department of Bioscience, Aarhus University, Aarhus C, Denmark
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15
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Jaquiéry J, Peccoud J, Ouisse T, Legeai F, Prunier-Leterme N, Gouin A, Nouhaud P, Brisson JA, Bickel R, Purandare S, Poulain J, Battail C, Lemaitre C, Mieuzet L, Le Trionnaire G, Simon JC, Rispe C. Disentangling the Causes for Faster-X Evolution in Aphids. Genome Biol Evol 2018; 10:507-520. [PMID: 29360959 PMCID: PMC5798017 DOI: 10.1093/gbe/evy015] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2018] [Indexed: 12/22/2022] Open
Abstract
The faster evolution of X chromosomes has been documented in several species, and results from the increased efficiency of selection on recessive alleles in hemizygous males and/or from increased drift due to the smaller effective population size of X chromosomes. Aphids are excellent models for evaluating the importance of selection in faster-X evolution because their peculiar life cycle and unusual inheritance of sex chromosomes should generally lead to equivalent effective population sizes for X and autosomes. Because we lack a high-density genetic map for the pea aphid, whose complete genome has been sequenced, we first assigned its entire genome to the X or autosomes based on ratios of sequencing depth in males (X0) to females (XX). Then, we computed nonsynonymous to synonymous substitutions ratios (dN/dS) for the pea aphid gene set and found faster evolution of X-linked genes. Our analyses of substitution rates, together with polymorphism and expression data, showed that relaxed selection is likely to be the greatest contributor to faster-X because a large fraction of X-linked genes are expressed at low rates and thus escape selection. Yet, a minor role for positive selection is also suggested by the difference between substitution rates for X and autosomes for male-biased genes (but not for asexual female-biased genes) and by lower Tajima’s D for X-linked compared with autosomal genes with highly male-biased expression patterns. This study highlights the relevance of organisms displaying alternative chromosomal inheritance to the understanding of forces shaping genome evolution.
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Affiliation(s)
- Julie Jaquiéry
- INRA UMR IGEPP Domaine de la Motte, Le Rheu, France.,CNRS UMR 6553 ECOBIO, Université de Rennes 1, France
| | - Jean Peccoud
- CNRS UMR 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Université de Poitiers, France
| | | | - Fabrice Legeai
- INRA UMR IGEPP Domaine de la Motte, Le Rheu, France.,INRIA Centre Rennes - Bretagne Atlantique, GenOuest, Rennes, France
| | | | - Anais Gouin
- INRA UMR IGEPP Domaine de la Motte, Le Rheu, France.,INRIA Centre Rennes - Bretagne Atlantique, GenOuest, Rennes, France
| | - Pierre Nouhaud
- Institute of Population Genetics, Vetmeduni Vienna, Vienna, Austria
| | | | - Ryan Bickel
- Department of Biology, University of Rochester
| | - Swapna Purandare
- Multidisciplinary Center for Advance Research and Studies (MCARS), Jamia Millia Islamia, New Delhi, India
| | - Julie Poulain
- Commissariat à l'Energie Atomique (CEA), Institut de Génomique (IG), Genoscope, Evry, France
| | - Christophe Battail
- Commissariat à l'Energie Atomique (CEA), Institut de Génomique (IG), Centre National de Génotypage (CNG), Evry, France
| | - Claire Lemaitre
- INRIA Centre Rennes - Bretagne Atlantique, GenOuest, Rennes, France
| | | | | | | | - Claude Rispe
- BIOEPAR, INRA, ONIRIS, La Chantrerie, Nantes, France
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16
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Coalescence and Linkage Disequilibrium in Facultatively Sexual Diploids. Genetics 2018; 210:683-701. [PMID: 30097538 DOI: 10.1534/genetics.118.301244] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 08/10/2018] [Indexed: 01/26/2023] Open
Abstract
Under neutrality, linkage disequilibrium results from physically linked sites having nonindependent coalescent histories. In obligately sexual organisms, meiotic recombination is the dominant force separating linked variants from one another, and thus in determining the decay of linkage disequilibrium with physical distance. In facultatively sexual diploid organisms that principally reproduce clonally, mechanisms of mitotic exchange are expected to become relatively more important in shaping linkage disequilibrium. Here we outline mathematical and computational models of a facultative-sex coalescent process that includes meiotic and mitotic recombination, via both crossovers and gene conversion, to determine how linkage disequilibrium is affected with facultative sex. We demonstrate that the degree to which linkage disequilibrium is broken down by meiotic recombination simply scales with the probability of sex if it is sufficiently high (much greater than [Formula: see text] for population size N). However, with very rare sex (occurring with frequency on the order of [Formula: see text]), mitotic gene conversion plays a particularly important and complicated role because it both breaks down associations between sites and removes within-individual diversity. Strong population structure under rare sex leads to lower average linkage disequilibrium values than in panmictic populations, due to the influence of low-frequency polymorphisms created by allelic sequence divergence acting in individual subpopulations. These analyses provide information on how to interpret observed linkage disequilibrium patterns in facultative sexuals and to determine what genomic forces are likely to shape them.
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17
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Nouhaud P, Gautier M, Gouin A, Jaquiéry J, Peccoud J, Legeai F, Mieuzet L, Smadja CM, Lemaitre C, Vitalis R, Simon JC. Identifying genomic hotspots of differentiation and candidate genes involved in the adaptive divergence of pea aphid host races. Mol Ecol 2018; 27:3287-3300. [PMID: 30010213 DOI: 10.1111/mec.14799] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 06/01/2018] [Accepted: 06/11/2018] [Indexed: 01/01/2023]
Abstract
Identifying the genomic bases of adaptation to novel environments is a long-term objective in evolutionary biology. Because genetic differentiation is expected to increase between locally adapted populations at the genes targeted by selection, scanning the genome for elevated levels of differentiation is a first step towards deciphering the genomic architecture underlying adaptive divergence. The pea aphid Acyrthosiphon pisum is a model of choice to address this question, as it forms a large complex of plant-specialized races and cryptic species, resulting from recent adaptive radiation. Here, we characterized genomewide polymorphisms in three pea aphid races specialized on alfalfa, clover and pea crops, respectively, which we sequenced in pools (poolseq). Using a model-based approach that explicitly accounts for selection, we identified 392 genomic hotspots of differentiation spanning 47.3 Mb and 2,484 genes (respectively, 9.12% of the genome size and 8.10% of its genes). Most of these highly differentiated regions were located on the autosomes, and overall differentiation was weaker on the X chromosome. Within these hotspots, high levels of absolute divergence between races suggest that these regions experienced less gene flow than the rest of the genome, most likely by contributing to reproductive isolation. Moreover, population-specific analyses showed evidence of selection in every host race, depending on the hotspot considered. These hotspots were significantly enriched for candidate gene categories that control host-plant selection and use. These genes encode 48 salivary proteins, 14 gustatory receptors, 10 odorant receptors, five P450 cytochromes and one chemosensory protein, which represent promising candidates for the genetic basis of host-plant specialization and ecological isolation in the pea aphid complex. Altogether, our findings open new research directions towards functional studies, for validating the role of these genes on adaptive phenotypes.
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Affiliation(s)
| | - Mathieu Gautier
- CBGP, Univ Montpellier, CIRAD, INRA, IRD, Montpellier SupAgro, Montpellier, France
- Institut de Biologie Computationnelle, Univ Montpellier, Montpellier, France
| | - Anaïs Gouin
- INRA, UMR 1349 IGEPP, Le Rheu, France
- Inria/IRISA GenScale, Rennes, France
| | | | - Jean Peccoud
- Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, Université de Poitiers, Poitiers, France
| | - Fabrice Legeai
- INRA, UMR 1349 IGEPP, Le Rheu, France
- Inria/IRISA GenScale, Rennes, France
| | | | - Carole M Smadja
- Institut des Sciences de l'Evolution (UMR 5554) - CNRS - IRD - EPHE - CIRAD -Université de Montpellier, Montpellier, France
| | | | - Renaud Vitalis
- CBGP, Univ Montpellier, CIRAD, INRA, IRD, Montpellier SupAgro, Montpellier, France
- Institut de Biologie Computationnelle, Univ Montpellier, Montpellier, France
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18
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Richard G, Legeai F, Prunier-Leterme N, Bretaudeau A, Tagu D, Jaquiéry J, Le Trionnaire G. Dosage compensation and sex-specific epigenetic landscape of the X chromosome in the pea aphid. Epigenetics Chromatin 2017. [PMID: 28638443 PMCID: PMC5471693 DOI: 10.1186/s13072-017-0137-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Background Heterogametic species display a differential number of sex chromosomes resulting in imbalanced transcription levels for these chromosomes between males and females. To correct this disequilibrium, dosage compensation mechanisms involving gene expression and chromatin accessibility regulations have emerged throughout evolution. In insects, these mechanisms have been extensively characterized only in Drosophila but not in insects of agronomical importance. Aphids are indeed major pests of a wide range of crops. Their remarkable ability to switch from asexual to sexual reproduction during their life cycle largely explains the economic losses they can cause. As heterogametic insects, male aphids are X0, while females (asexual and sexual) are XX. Results Here, we analyzed transcriptomic and open chromatin data obtained from whole male and female individuals to evaluate the putative existence of a dosage compensation mechanism involving differential chromatin accessibility of the pea aphid’s X chromosome. Transcriptomic analyses first showed X/AA and XX/AA expression ratios for expressed genes close to 1 in males and females, respectively, suggesting dosage compensation in the pea aphid. Analyses of open chromatin data obtained by Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE-seq) revealed a X chromosome chromatin accessibility globally and significantly higher in males than in females, while autosomes’ chromatin accessibility is similar between sexes. Moreover, chromatin environment of X-linked genes displaying similar expression levels in males and females—and thus likely to be compensated—is significantly more accessible in males. Conclusions Our results suggest the existence of an underlying epigenetic mechanism enhancing the X chromosome chromatin accessibility in males to allow X-linked gene dose correction between sexes in the pea aphid, similar to Drosophila. Our study gives new evidence into the comprehension of dosage compensation in link with chromatin biology in insects and newly in a major crop pest, taking benefits from both transcriptomic and open chromatin data. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0137-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gautier Richard
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Fabrice Legeai
- BIPAA, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Campus Beaulieu, Rennes, France.,Genscale, INRIA, IRISA, Campus Beaulieu, Rennes, France
| | - Nathalie Prunier-Leterme
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Anthony Bretaudeau
- BIPAA, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Campus Beaulieu, Rennes, France.,Genouest, INRIA, IRISA, Campus Beaulieu, Rennes, France
| | - Denis Tagu
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Julie Jaquiéry
- CNRS, UMR 6553, EcoBio, University of Rennes 1, 35042 Rennes, France
| | - Gaël Le Trionnaire
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
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19
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Pita S, Panzera F, Sánchez A, Palomeque T, Lorite P. Chromosome Painting in Triatomine Insects Reveals Shared Sequences Between X Chromosomes and Autosomes. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:44-49. [PMID: 28082631 DOI: 10.1093/jme/tjw146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/09/2016] [Indexed: 06/06/2023]
Abstract
In order to provide a broad picture on the origin and evolution of holocentric X chromosomes in heteropteran species, we prepared a sex chromosome painting probe by microdissection of the X1 and X2 chromosomes from a kissing bug Mepraia spinolai (Hemiptera: Reduviidae: Triatominae). Fluorescence in situ hybridization on four species of the Triatomini having different amounts of autosomal heterochromatin and sex chromosome systems show that the Xs probe hybridizes on the euchromatin, located both on autosomes and X chromosomes. The heterochromatic Y chromosome and autosomal heterochromatic regions always appear free of hybridization signals. The hybridization results of the Xs probe on Rhodnius prolixus (Rhodniini) is completely different to that observed in Triatomini species. The hybridization signals are small and scattered on all euchromatin, without specific regions including the X chromosome. These results are in accordance with previous data obtained by genomic in situ hybridization and fluorescent banding, suggesting a clear differentiation in the repeat sequence composition of both sex chromosomes between Triatomini and Rhodniini tribes. These results also support that each sex chromosome in Triatomini has evolved independently from different autosomal pairs of a common ancestor, as described in other insect orders.
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Affiliation(s)
- Sebastián Pita
- Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay (; )
| | - Francisco Panzera
- Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay (; )
| | - Antonio Sánchez
- Departamento de Biología Experimental, Área de Genética, Universidad de Jaén, Av. Lagunillas s/n., 23071 Jaén, Spain (; ; )
| | - Teresa Palomeque
- Departamento de Biología Experimental, Área de Genética, Universidad de Jaén, Av. Lagunillas s/n., 23071 Jaén, Spain (; ; )
| | - Pedro Lorite
- Departamento de Biología Experimental, Área de Genética, Universidad de Jaén, Av. Lagunillas s/n., 23071 Jaén, Spain (; ; )
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20
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Abstract
Is there a correlation between miRNA diversity and levels of organismic complexity? Exhibiting extraordinary levels of morphological and developmental complexity, insects are the most diverse animal class on earth. Their evolutionary success was in particular shaped by the innovation of holometabolan metamorphosis in endopterygotes. Previously, miRNA evolution had been linked to morphological complexity, but astonishing variation in the currently available miRNA complements of insects made this link unclear. To address this issue, we sequenced the miRNA complement of the hemimetabolan Blattella germanica and reannotated that of two other hemimetabolan species, Locusta migratoria and Acyrthosiphon pisum, and of four holometabolan species, Apis mellifera, Tribolium castaneum, Bombyx mori and Drosophila melanogaster. Our analyses show that the variation of insect miRNAs is an artefact mainly resulting from poor sampling and inaccurate miRNA annotation, and that insects share a conserved microRNA toolkit of 65 families exhibiting very low variation. For example, the evolutionary shift toward a complete metamorphosis was accompanied only by the acquisition of three and the loss of one miRNA families.
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21
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Affiliation(s)
- Sonja Grath
- Department of Biology II, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Planegg, Germany; ,
| | - John Parsch
- Department of Biology II, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Planegg, Germany; ,
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22
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Contrasting Levels of Molecular Evolution on the Mouse X Chromosome. Genetics 2016; 203:1841-57. [PMID: 27317678 DOI: 10.1534/genetics.116.186825] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 06/08/2016] [Indexed: 11/18/2022] Open
Abstract
The mammalian X chromosome has unusual evolutionary dynamics compared to autosomes. Faster-X evolution of spermatogenic protein-coding genes is known to be most pronounced for genes expressed late in spermatogenesis, but it is unclear if these patterns extend to other forms of molecular divergence. We tested for faster-X evolution in mice spanning three different forms of molecular evolution-divergence in protein sequence, gene expression, and DNA methylation-across different developmental stages of spermatogenesis. We used FACS to isolate individual cell populations and then generated cell-specific transcriptome profiles across different stages of spermatogenesis in two subspecies of house mice (Mus musculus), thereby overcoming a fundamental limitation of previous studies on whole tissues. We found faster-X protein evolution at all stages of spermatogenesis and faster-late protein evolution for both X-linked and autosomal genes. In contrast, there was less expression divergence late in spermatogenesis (slower late) on the X chromosome and for autosomal genes expressed primarily in testis (testis-biased). We argue that slower-late expression divergence reflects strong regulatory constraints imposed during this critical stage of sperm development and that these constraints are particularly acute on the tightly regulated sex chromosomes. We also found slower-X DNA methylation divergence based on genome-wide bisulfite sequencing of sperm from two species of mice (M. musculus and M. spretus), although it is unclear whether slower-X DNA methylation reflects development constraints in sperm or other X-linked phenomena. Our study clarifies key differences in patterns of regulatory and protein evolution across spermatogenesis that are likely to have important consequences for mammalian sex chromosome evolution, male fertility, and speciation.
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23
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Pal A, Vicoso B. The X Chromosome of Hemipteran Insects: Conservation, Dosage Compensation and Sex-Biased Expression. Genome Biol Evol 2015; 7:3259-68. [PMID: 26556591 PMCID: PMC4700948 DOI: 10.1093/gbe/evv215] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Insects of the order Hemiptera (true bugs) use a wide range of mechanisms of sex determination, including genetic sex determination, paternal genome elimination, and haplodiploidy. Genetic sex determination, the prevalent mode, is generally controlled by a pair of XY sex chromosomes or by an XX/X0 system, but different configurations that include additional sex chromosomes are also present. Although this diversity of sex determining systems has been extensively studied at the cytogenetic level, only the X chromosome of the model pea aphid Acyrthosiphon pisum has been analyzed at the genomic level, and little is known about X chromosome biology in the rest of the order. In this study, we take advantage of published DNA- and RNA-seq data from three additional Hemiptera species to perform a comparative analysis of the gene content and expression of the X chromosome throughout this clade. We find that, despite showing evidence of dosage compensation, the X chromosomes of these species show female-biased expression, and a deficit of male-biased genes, in direct contrast to the pea aphid X. We further detect an excess of shared gene content between these very distant species, suggesting that despite the diversity of sex determining systems, the same chromosomal element is used as the X throughout a large portion of the order.
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Affiliation(s)
- Arka Pal
- Institute of Science and Technology Austria, Klosterneuburg, Austria Center for Ecological Sciences, Indian Institute of Science, Bangalore, India
| | - Beatriz Vicoso
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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24
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Llopart A. Parallel faster-X evolution of gene expression and protein sequences in Drosophila: beyond differences in expression properties and protein interactions. PLoS One 2015; 10:e0116829. [PMID: 25789611 PMCID: PMC4366066 DOI: 10.1371/journal.pone.0116829] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 12/15/2014] [Indexed: 12/27/2022] Open
Abstract
Population genetics models predict that the X (or Z) chromosome will evolve at faster rates than the autosomes in XY (or ZW) systems. Studies of molecular evolution using large datasets in multiple species have provided evidence supporting this faster-X effect in protein-coding sequences and, more recently, in transcriptomes. However, X-linked and autosomal genes differ significantly in important properties besides hemizygosity in males, including gene expression levels, tissue specificity in gene expression, and the number of interactions in which they are involved (i.e., protein-protein or DNA-protein interactions). Most important, these properties are known to correlate with rates of evolution, which raises the question of whether differences between the X chromosome and autosomes in gene properties, rather than hemizygosity, are sufficient to explain faster-X evolution. Here I investigate this possibility using whole genome sequences and transcriptomes of Drosophila yakuba and D. santomea and show that this is not the case. Additional factors are needed to account for faster-X evolution of both gene expression and protein-coding sequences beyond differences in gene properties, likely a higher incidence of positive selection in combination with the accumulation of weakly deleterious mutations.
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Affiliation(s)
- Ana Llopart
- Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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25
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Jaquiéry J, Stoeckel S, Larose C, Nouhaud P, Rispe C, Mieuzet L, Bonhomme J, Mahéo F, Legeai F, Gauthier JP, Prunier-Leterme N, Tagu D, Simon JC. Genetic control of contagious asexuality in the pea aphid. PLoS Genet 2014; 10:e1004838. [PMID: 25473828 PMCID: PMC4256089 DOI: 10.1371/journal.pgen.1004838] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 10/17/2014] [Indexed: 11/18/2022] Open
Abstract
Although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of such shifts toward asexuality remain largely unknown. We addressed this issue in an aphid species where both sexual and obligate asexual lineages coexist in natural populations. These sexual and asexual lineages may occasionally interbreed because some asexual lineages maintain a residual production of males potentially able to mate with the females produced by sexual lineages. Hence, this species is an ideal model to study the genetic basis of the loss of sexual reproduction with quantitative genetic and population genomic approaches. Our analysis of the co-segregation of ∼ 300 molecular markers and reproductive phenotype in experimental crosses pinpointed an X-linked region controlling obligate asexuality, this state of character being recessive. A population genetic analysis (>400-marker genome scan) on wild sexual and asexual genotypes from geographically distant populations under divergent selection for reproductive strategies detected a strong signature of divergent selection in the genomic region identified by the experimental crosses. These population genetic data confirm the implication of the candidate region in the control of reproductive mode in wild populations originating from 700 km apart. Patterns of genetic differentiation along chromosomes suggest bidirectional gene flow between populations with distinct reproductive modes, supporting contagious asexuality as a prevailing route to permanent parthenogenesis in pea aphids. This genetic system provides new insights into the mechanisms of coexistence of sexual and asexual aphid lineages.
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Affiliation(s)
- Julie Jaquiéry
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Solenn Stoeckel
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Chloé Larose
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Pierre Nouhaud
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Claude Rispe
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Lucie Mieuzet
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Joël Bonhomme
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Frédérique Mahéo
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Fabrice Legeai
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
- INRIA Centre Rennes - Bretagne Atlantique, GenOuest, Campus de Beaulieu, Rennes, France
| | - Jean-Pierre Gauthier
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Nathalie Prunier-Leterme
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Denis Tagu
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
| | - Jean-Christophe Simon
- INRA, UMR1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France
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26
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Nouhaud P, Peccoud J, Mahéo F, Mieuzet L, Jaquiéry J, Simon JC. Genomic regions repeatedly involved in divergence among plant-specialized pea aphid biotypes. J Evol Biol 2014; 27:2013-20. [PMID: 24953130 DOI: 10.1111/jeb.12441] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Revised: 04/10/2014] [Accepted: 05/19/2014] [Indexed: 01/28/2023]
Abstract
Understanding the genetic bases of biological diversification is a long-standing goal in evolutionary biology. Here, we investigate whether replicated cases of adaptive divergence involve the same genomic regions in the pea aphid, Acyrthosiphon pisum, a large complex of genetically differentiated biotypes, each specialized on different species of legumes. A previous study identified genomic regions putatively involved in host-plant adaptation and/or reproductive isolation by performing a hierarchical genome scan in three biotypes. This led to the identification of 11 F(ST) outliers among 390 polymorphic microsatellite markers. In this study, the outlier status of these 11 loci was assessed in eight biotypes specialized on other host plants. Four of the 11 previously identified outliers showed greater genetic differentiation among these additional biotypes than expected under the null hypothesis of neutral evolution (α < 0.01). Whether these hotspots of genomic divergence result from adaptive events, intrinsic barriers or reduced recombination is discussed.
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Affiliation(s)
- P Nouhaud
- INRA, UMR 1349 IGEPP, Le Rheu, France
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27
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Meisel RP, Connallon T. The faster-X effect: integrating theory and data. Trends Genet 2013; 29:537-44. [PMID: 23790324 PMCID: PMC3755111 DOI: 10.1016/j.tig.2013.05.009] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/02/2013] [Accepted: 05/20/2013] [Indexed: 11/30/2022]
Abstract
Population genetics theory predicts that X (or Z) chromosomes could play disproportionate roles in speciation and evolutionary divergence, and recent genome-wide analyses have identified situations in which X or Z-linked divergence exceeds that on the autosomes (the so-called 'faster-X effect'). Here, we summarize the current state of both the theory and data surrounding the study of faster-X evolution. Our survey indicates that the faster-X effect is pervasive across a taxonomically diverse array of evolutionary lineages. These patterns could be informative of the dominance or recessivity of beneficial mutations and the nature of genetic variation acted upon by natural selection. We also identify several aspects of disagreement between these empirical results and the population genetic models used to interpret them. However, there are clearly delineated aspects of the problem for which additional modeling and collection of genomic data will address these discrepancies and provide novel insights into the population genetics of adaptation.
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28
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Jaquiéry J, Rispe C, Roze D, Legeai F, Le Trionnaire G, Stoeckel S, Mieuzet L, Da Silva C, Poulain J, Prunier-Leterme N, Ségurens B, Tagu D, Simon JC. Masculinization of the x chromosome in the pea aphid. PLoS Genet 2013; 9:e1003690. [PMID: 23950732 PMCID: PMC3738461 DOI: 10.1371/journal.pgen.1003690] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 06/17/2013] [Indexed: 11/18/2022] Open
Abstract
Evolutionary theory predicts that sexually antagonistic mutations accumulate differentially on the X chromosome and autosomes in species with an XY sex-determination system, with effects (masculinization or feminization of the X) depending on the dominance of mutations. Organisms with alternative modes of inheritance of sex chromosomes offer interesting opportunities for studying sexual conflicts and their resolution, because expectations for the preferred genomic location of sexually antagonistic alleles may differ from standard systems. Aphids display an XX/X0 system and combine an unusual inheritance of the X chromosome with the alternation of sexual and asexual reproduction. In this study, we first investigated theoretically the accumulation of sexually antagonistic mutations on the aphid X chromosome. Our results show that i) the X is always more favourable to the spread of male-beneficial alleles than autosomes, and should thus be enriched in sexually antagonistic alleles beneficial for males, ii) sexually antagonistic mutations beneficial for asexual females accumulate preferentially on autosomes, iii) in contrast to predictions for standard systems, these qualitative results are not affected by the dominance of mutations. Under the assumption that sex-biased gene expression evolves to solve conflicts raised by the spread of sexually antagonistic alleles, one expects that male-biased genes should be enriched on the X while asexual female-biased genes should be enriched on autosomes. Using gene expression data (RNA-Seq) in males, sexual females and asexual females of the pea aphid, we confirm these theoretical predictions. Although other mechanisms than the resolution of sexual antagonism may lead to sex-biased gene expression, we argue that they could hardly explain the observed difference between X and autosomes. On top of reporting a strong masculinization of the aphid X chromosome, our study highlights the relevance of organisms displaying an alternative mode of sex chromosome inheritance to understanding the forces shaping chromosome evolution.
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Affiliation(s)
- Julie Jaquiéry
- INRA, UMR 1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, Le Rheu, France.
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29
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Bickel RD, Dunham JP, Brisson JA. Widespread selection across coding and noncoding DNA in the pea aphid genome. G3 (BETHESDA, MD.) 2013; 3:993-1001. [PMID: 23589520 PMCID: PMC3689810 DOI: 10.1534/g3.113.005793] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/08/2013] [Indexed: 12/03/2022]
Abstract
Genome-wide patterns of diversity and selection are critical measures for understanding how evolution has shaped the genome. Yet, these population genomic estimates are available for only a limited number of model organisms. Here we focus on the population genomics of the pea aphid (Acyrthosiphon pisum). The pea aphid is an emerging model system that exhibits a range of intriguing biological traits not present in classic model systems. We performed low-coverage genome resequencing of 21 clonal pea aphid lines collected from alfalfa host plants in North America to characterize genome-wide patterns of diversity and selection. We observed an excess of low-frequency polymorphisms throughout coding and noncoding DNA, which we suggest is the result of a founding event and subsequent population expansion in North America. Most gene regions showed lower levels of Tajima's D than synonymous sites, suggesting that the majority of the genome is not evolving neutrally but rather exhibits significant constraint. Furthermore, we used the pea aphid's unique manner of X-chromosome inheritance to assign genomic scaffolds to either autosomes or the X chromosome. Comparing autosomal vs. X-linked sequence variation, we discovered that autosomal genes show an excess of low frequency variants indicating that purifying selection acts more efficiently on the X chromosome. Overall, our results provide a critical first step in characterizing the genetic diversity and evolutionary pressures on an aphid genome.
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Affiliation(s)
- Ryan D Bickel
- University of Nebraska, School of Biological Sciences, Lincoln, Nebraska 68588, USA.
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30
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Kayserili MA, Gerrard DT, Tomancak P, Kalinka AT. An excess of gene expression divergence on the X chromosome in Drosophila embryos: implications for the faster-X hypothesis. PLoS Genet 2012; 8:e1003200. [PMID: 23300473 PMCID: PMC3531489 DOI: 10.1371/journal.pgen.1003200] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 11/19/2012] [Indexed: 12/26/2022] Open
Abstract
The X chromosome is present as a single copy in the heterogametic sex, and this hemizygosity is expected to drive unusual patterns of evolution on the X relative to the autosomes. For example, the hemizgosity of the X may lead to a lower chromosomal effective population size compared to the autosomes, suggesting that the X might be more strongly affected by genetic drift. However, the X may also experience stronger positive selection than the autosomes, because recessive beneficial mutations will be more visible to selection on the X where they will spend less time being masked by the dominant, less beneficial allele--a proposal known as the faster-X hypothesis. Thus, empirical studies demonstrating increased genetic divergence on the X chromosome could be indicative of either adaptive or non-adaptive evolution. We measured gene expression in Drosophila species and in D. melanogaster inbred strains for both embryos and adults. In the embryos we found that expression divergence is on average more than 20% higher for genes on the X chromosome relative to the autosomes; but in contrast, in the inbred strains, gene expression variation is significantly lower on the X chromosome. Furthermore, expression divergence of genes on Muller's D element is significantly greater along the branch leading to the obscura sub-group, in which this element segregates as a neo-X chromosome. In the adults, divergence is greatest on the X chromosome for males, but not for females, yet in both sexes inbred strains harbour the lowest level of gene expression variation on the X chromosome. We consider different explanations for our results and conclude that they are most consistent within the framework of the faster-X hypothesis.
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Affiliation(s)
- Melek A. Kayserili
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Dave T. Gerrard
- Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
| | - Pavel Tomancak
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
| | - Alex T. Kalinka
- Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, Germany
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31
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Jaquiéry J, Stoeckel S, Nouhaud P, Mieuzet L, Mahéo F, Legeai F, Bernard N, Bonvoisin A, Vitalis R, Simon JC. Genome scans reveal candidate regions involved in the adaptation to host plant in the pea aphid complex. Mol Ecol 2012; 21:5251-64. [PMID: 23017212 DOI: 10.1111/mec.12048] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 08/06/2012] [Indexed: 11/26/2022]
Abstract
A major goal in evolutionary biology is to uncover the genetic basis of adaptation. Divergent selection exerted on ecological traits may result in adaptive population differentiation and reproductive isolation and affect differentially the level of genetic divergence along the genome. Genome-wide scan of large sets of individuals from multiple populations is a powerful approach to identify loci or genomic regions under ecologically divergent selection. Here, we focused on the pea aphid, a species complex of divergent host races, to explore the organization of the genomic divergence associated with host plant adaptation and ecological speciation. We analysed 390 microsatellite markers located at variable distances from predicted genes in replicate samples of sympatric populations of the pea aphid collected on alfalfa, red clover and pea, which correspond to three common host-adapted races reported in this species complex. Using a method that accounts for the hierarchical structure of our data set, we found a set of 11 outlier loci that show higher genetic differentiation between host races than expected under the null hypothesis of neutral evolution. Two of the outliers are close to olfactory receptor genes and three other nearby genes encoding salivary proteins. The remaining outliers are located in regions with genes of unknown functions, or which functions are unlikely to be involved in interactions with the host plant. This study reveals genetic signatures of divergent selection across the genome and provides an inventory of candidate genes responsible for plant specialization in the pea aphid, thereby setting the stage for future functional studies.
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Affiliation(s)
- J Jaquiéry
- INRA, UMR 1349, Institute of Genetics, Environment and Plant Protection, Domaine de la Motte, BP 35327, 35653, Le Rheu Cedex, France
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