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Huylmans AK, Macon A, Hontoria F, Vicoso B. Transitions to asexuality and evolution of gene expression in Artemia brine shrimp. Proc Biol Sci 2021; 288:20211720. [PMID: 34547909 PMCID: PMC8456138 DOI: 10.1098/rspb.2021.1720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 08/31/2021] [Indexed: 11/12/2022] Open
Abstract
While sexual reproduction is widespread among many taxa, asexual lineages have repeatedly evolved from sexual ancestors. Despite extensive research on the evolution of sex, it is still unclear whether this switch represents a major transition requiring major molecular reorganization, and how convergent the changes involved are. In this study, we investigated the phylogenetic relationship and patterns of gene expression of sexual and asexual lineages of Eurasian Artemia brine shrimp, to assess how gene expression patterns are affected by the transition to asexuality. We find only a few genes that are consistently associated with the evolution of asexuality, suggesting that this shift may not require an extensive overhauling of the meiotic machinery. While genes with sex-biased expression have high rates of expression divergence within Eurasian Artemia, neither female- nor male-biased genes appear to show unusual evolutionary patterns after sexuality is lost, contrary to theoretical expectations.
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Affiliation(s)
- Ann Kathrin Huylmans
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria
| | - Ariana Macon
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria
| | - Francisco Hontoria
- Instituto de Acuicultura de Torre de la Sal (IATS-CSIC), 12595 Ribera de Cabanes, Castellón, Spain
| | - Beatriz Vicoso
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg 3400, Austria
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2
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Bast J, Parker DJ, Dumas Z, Jalvingh KM, Tran Van P, Jaron KS, Figuet E, Brandt A, Galtier N, Schwander T. Consequences of Asexuality in Natural Populations: Insights from Stick Insects. Mol Biol Evol 2019; 35:1668-1677. [PMID: 29659991 PMCID: PMC5995167 DOI: 10.1093/molbev/msy058] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Recombination is a fundamental process with significant impacts on genome evolution. Predicted consequences of the loss of recombination include a reduced effectiveness of selection, changes in the amount of neutral polymorphisms segregating in populations, and an arrest of GC-biased gene conversion. Although these consequences are empirically well documented for nonrecombining genome portions, it remains largely unknown if they extend to the whole genome scale in asexual organisms. We identify the consequences of asexuality using de novo transcriptomes of five independently derived, obligately asexual lineages of stick insects, and their sexual sister-species. We find strong evidence for higher rates of deleterious mutation accumulation, lower levels of segregating polymorphisms and arrested GC-biased gene conversion in asexuals as compared with sexuals. Taken together, our study conclusively shows that predicted consequences of genome evolution under asexuality can indeed be found in natural populations.
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Affiliation(s)
- Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Darren J Parker
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Zoé Dumas
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Kirsten M Jalvingh
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Patrick Tran Van
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Kamil S Jaron
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Emeric Figuet
- Institute of Evolutionary Sciences, University of Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Alexander Brandt
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, Goettingen, Germany
| | - Nicolas Galtier
- Institute of Evolutionary Sciences, University of Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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3
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Brandt A, Bast J, Scheu S, Meusemann K, Donath A, Schütte K, Machida R, Kraaijeveld K. No signal of deleterious mutation accumulation in conserved gene sequences of extant asexual hexapods. Sci Rep 2019; 9:5338. [PMID: 30926861 PMCID: PMC6441085 DOI: 10.1038/s41598-019-41821-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 03/18/2019] [Indexed: 11/15/2022] Open
Abstract
Loss of sex and recombination is generally assumed to impede the effectiveness of purifying selection and to result in the accumulation of slightly deleterious mutations. Empirical evidence for this has come from several studies investigating mutational load in a small number of individual genes. However, recent whole transcriptome based studies have yielded inconsistent results, hence questioning the validity of the assumption of mutational meltdown in asexual populations. Here, we study the effectiveness of purifying selection in eight asexual hexapod lineages and their sexual relatives, as present in the 1 K Insect Transcriptome Evolution (1KITE) project, covering eight hexapod groups. We analyse the accumulation of slightly deleterious nonsynonymous and synonymous point mutations in 99 single copy orthologue protein-coding loci shared among the investigated taxa. While accumulation rates of nonsynonymous mutations differed between genes and hexapod groups, we found no effect of reproductive mode on the effectiveness of purifying selection acting at nonsynonymous and synonymous sites. Although the setup of this study does not fully rule out nondetection of subtle effects, our data does not support the established consensus of asexual lineages undergoing ‘mutational meltdown’.
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Affiliation(s)
- Alexander Brandt
- University of Göttingen, JF Blumenbach Institute of Zoology and Anthropology, Untere Karspüle 2, D-37073, Göttingen, Germany.
| | - Jens Bast
- University of Lausanne, Department of Ecology and Evolution, UNIL Sorge, Le Biophore, CH-1015, Lausanne, Switzerland
| | - Stefan Scheu
- University of Göttingen, JF Blumenbach Institute of Zoology and Anthropology, Untere Karspüle 2, D-37073, Göttingen, Germany
| | - Karen Meusemann
- University of Freiburg, Biology I, Evolutionary Biology & Ecology, Hauptstraße 1, D-79104, Freiburg, Germany.,Center for Molecular Biodiversity Research (ZMB), Zoological Research Museum Alexander König, Adenauerallee 160, D-53113, Bonn, Germany
| | - Alexander Donath
- Center for Molecular Biodiversity Research (ZMB), Zoological Research Museum Alexander König, Adenauerallee 160, D-53113, Bonn, Germany
| | - Kai Schütte
- University of Hamburg, Faculty of Mathematics, Informatics and Natural Sciences, Department of Biology, Institute of Zoology, Research Unit Animal Ecology and Conservation, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Ryuichiro Machida
- Sugadaira Research Station, Mountain Science Center, University of Tsukuba, 1278-294, Sugadaira Kogen, Ueda, Nagano, 386-2204, Japan
| | - Ken Kraaijeveld
- University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Science Park 904, 1090 GE, Amsterdam, The Netherlands
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4
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Tvedte ES, Logsdon JM, Forbes AA. Sex loss in insects: causes of asexuality and consequences for genomes. CURRENT OPINION IN INSECT SCIENCE 2019; 31:77-83. [PMID: 31109677 DOI: 10.1016/j.cois.2018.11.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 11/03/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
Boasting a staggering diversity of reproductive strategies, insects provide attractive models for the comparative study of the causes and consequences of transitions to asexuality. We provide an overview of some contemporary studies of reproductive systems in insects and compile an initial database of asexual insect genome resources. Insect systems have already yielded some important insights into various mechanisms by which sex is lost, including genetic, endosymbiont-mediated, and hybridization. Studies of mutation and substitution after loss of sex provide the strongest empirical support for hypothesized effects of asexuality, whereas there is mixed evidence for ecological hypotheses such as increased parasite load and altered niche breadth in asexuals. Most hypotheses have been explored in a select few taxa (e.g. stick insects, aphids), such that much of the great taxonomic breadth of insects remain understudied. Given the variation in the proximate causes of asexuality in insects, we argue for expanding the taxonomic breadth of study systems. Despite some challenges for investigating sex in insects, the increasing cost-effectiveness of genomic sequencing makes data generation for closely-related asexual and sexual lineages increasingly feasible.
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Affiliation(s)
- Eric S Tvedte
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, United States.
| | - John M Logsdon
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Andrew A Forbes
- Department of Biology, University of Iowa, Iowa City, IA, United States
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Abstract
A major current molecular evolution challenge is to link comparative genomic patterns to species' biology and ecology. Breeding systems are pivotal because they affect many population genetic processes and thus genome evolution. We review theoretical predictions and empirical evidence about molecular evolutionary processes under three distinct breeding systems-outcrossing, selfing, and asexuality. Breeding systems may have a profound impact on genome evolution, including molecular evolutionary rates, base composition, genomic conflict, and possibly genome size. We present and discuss the similarities and differences between the effects of selfing and clonality. In reverse, comparative and population genomic data and approaches help revisiting old questions on the long-term evolution of breeding systems.
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Affiliation(s)
- Sylvain Glémin
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France
| | - Clémentine M François
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France
| | - Nicolas Galtier
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France.
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Brandt A, Schaefer I, Glanz J, Schwander T, Maraun M, Scheu S, Bast J. Effective purifying selection in ancient asexual oribatid mites. Nat Commun 2017; 8:873. [PMID: 29026136 PMCID: PMC5638860 DOI: 10.1038/s41467-017-01002-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 08/08/2017] [Indexed: 11/29/2022] Open
Abstract
Sex is beneficial in the long term because it can prevent mutational meltdown through increased effectiveness of selection. This idea is supported by empirical evidence of deleterious mutation accumulation in species with a recent transition to asexuality. Here, we study the effectiveness of purifying selection in oribatid mites which have lost sex millions of years ago and diversified into different families and species while reproducing asexually. We compare the accumulation of deleterious nonsynonymous and synonymous mutations between three asexual and three sexual lineages using transcriptome data. Contrasting studies of young asexual lineages, we find evidence for strong purifying selection that is more effective in asexual as compared to sexual oribatid mite lineages. Our results suggest that large populations likely sustain effective purifying selection and facilitate the escape of mutational meltdown in the absence of sex. Thus, sex per se is not a prerequisite for the long-term persistence of animal lineages. Asexual reproduction is thought to be an evolutionary dead end in eukaryotes because deleterious mutations will not be purged effectively. Here, Brandt and colleagues show that anciently asexual oribatid mites in fact have reduced accumulation of deleterious mutations compared to their sexual relatives.
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Affiliation(s)
- Alexander Brandt
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany.
| | - Ina Schaefer
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany
| | - Julien Glanz
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, UNIL Sorge, Le Biophore, CH-1015, Lausanne, Switzerland
| | - Mark Maraun
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany
| | - Stefan Scheu
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany.,Center of Biodiversity and Sustainable Land Use, Georg-August-University Goettingen, Untere Karspuele 2, DE-37073, Goettingen, Germany
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, UNIL Sorge, Le Biophore, CH-1015, Lausanne, Switzerland.
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Duan X, Wang K, Su S, Tian R, Li Y, Chen M. De novo transcriptome analysis and microsatellite marker development for population genetic study of a serious insect pest, Rhopalosiphum padi (L.) (Hemiptera: Aphididae). PLoS One 2017; 12:e0172513. [PMID: 28212394 PMCID: PMC5315398 DOI: 10.1371/journal.pone.0172513] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/05/2017] [Indexed: 11/21/2022] Open
Abstract
The bird cherry-oat aphid, Rhopalosiphum padi (L.), is one of the most abundant aphid pests of cereals and has a global distribution. Next-generation sequencing (NGS) is a rapid and efficient method for developing molecular markers. However, transcriptomic and genomic resources of R. padi have not been investigated. In this study, we used transcriptome information obtained by RNA-Seq to develop polymorphic microsatellites for investigating population genetics in this species. The transcriptome of R. padi was sequenced on an Illumina HiSeq 2000 platform. A total of 114.4 million raw reads with a GC content of 40.03% was generated. The raw reads were cleaned and assembled into 29,467 unigenes with an N50 length of 1,580 bp. Using several public databases, 82.47% of these unigenes were annotated. Of the annotated unigenes, 8,022 were assigned to COG pathways, 9,895 were assigned to GO pathways, and 14,586 were mapped to 257 KEGG pathways. A total of 7,936 potential microsatellites were identified in 5,564 unigenes, 60 of which were selected randomly and amplified using specific primer pairs. Fourteen loci were found to be polymorphic in the four R. padi populations. The transcriptomic data presented herein will facilitate gene discovery, gene analyses, and development of molecular markers for future studies of R. padi and other closely related aphid species.
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Affiliation(s)
- Xinle Duan
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China.,College of Bee Science, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kang Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China
| | - Sha Su
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China
| | - Ruizheng Tian
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China
| | - Yuting Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China
| | - Maohua Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Key Laboratory of Crop Pest Integrated Pest Management on the Loess Plateau of Ministry of Agriculture College of Plant Protection, Northwest A&F University, Yangling, China
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8
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Hartfield M. Evolutionary genetic consequences of facultative sex and outcrossing. J Evol Biol 2015; 29:5-22. [DOI: 10.1111/jeb.12770] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/24/2015] [Accepted: 09/28/2015] [Indexed: 01/16/2023]
Affiliation(s)
- M. Hartfield
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON Canada
- Bioinformatics Research Centre; University of Aarhus; Aarhus Denmark
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9
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Flores-López CA, Machado CA. Differences in inferred genome-wide signals of positive selection during the evolution of Trypanosoma cruzi and Leishmania spp. lineages: A result of disparities in host and tissue infection ranges? INFECTION GENETICS AND EVOLUTION 2015; 33:37-46. [DOI: 10.1016/j.meegid.2015.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 03/19/2015] [Accepted: 04/09/2015] [Indexed: 01/21/2023]
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10
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Schwander T, Marais G, Roze D. Sex uncovered: the evolutionary biology of reproductive systems. J Evol Biol 2015; 27:1287-91. [PMID: 24975885 DOI: 10.1111/jeb.12424] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- T Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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11
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Mitochondrial (COI) and nuclear (EF-1α) DNA variability of Rhopalosiphum padi and Rhopalosiphum nymphaeae (Hemiptera: Aphididae) in Lithuania. Biologia (Bratisl) 2015. [DOI: 10.2478/s11756-014-0475-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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12
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Wang D, Liu Q, Jones HD, Bruce T, Xia L. Comparative transcriptomic analyses revealed divergences of two agriculturally important aphid species. BMC Genomics 2014; 15:1023. [PMID: 25424897 PMCID: PMC4301665 DOI: 10.1186/1471-2164-15-1023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 11/06/2014] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Grain aphid (Sitobion avenae F) and pea aphid (Acyrthosiphon pisum) are two agriculturally important pest species, which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses. Although a close phylogenetic relationship between grain aphid and pea aphid was proposed, the biological variations between these two aphid species are obvious. While the host ranges of grain aphid is restricted to cereal crops and in particular wheat, that of pea aphid is wider, mainly colonizing leguminous plant species. Until now, the genetic factors underlying the divergence between grain aphid and pea aphid still remain unclear due to the limited genomic data of grain aphid available in public databases. RESULTS Based on a set of transcriptome data of grain aphid generated by using Roche 454 GS-FLX pyrosequencing, comparative analysis between this set of transcriptome data of grain aphid and mRNA sequences of pea aphid available in the public databases was performed. Compared with mRNA sequences of pea aphid, 4,857 unigenes were found to be specifically presented in the transcriptome of grain aphid under the rearing conditions described in this study. Furthermore, 3,368 orthologous pairs which could be calculated with both nonsynonymous (Ka) and synonymous (Ks) substitutions were used to infer their sequence divergences. The average differences in the coding, 5' and 3' untranslated regions of these orthologs were 10.53%, 21.29% and 18.96%, respectively. Moreover, of 340 orthologs which were identified to have evolved in response to positive selection based on the rates of Ka and Ks substitutions, 186 were predicted to be involved in secondary metabolism and xenobiotic metabolisms which might contribute to the divergence of these two aphid species. CONCLUSIONS The comprehensive transcriptome divergent sequence analysis between grain aphid and pea aphid provides an invaluable resource for the investigation of genes involved in host plant adaptation and evolution. Moreover, the demonstration of divergent transcriptome sequences between grain aphid and pea aphid pave the way for the investigation of the molecular mechanisms underpinning the biological variations of these two agriculturally important aphid species.
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Affiliation(s)
| | | | | | | | - Lanqin Xia
- Institute of Crop Sciences /The National Key Facility for Crop Gene Resource and Genetic Improvement, Chinese Academy of Agricultural Sciences (CAAS), 12 Zhongguanchun South Street, Beijing 10081, China.
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13
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Glémin S, Muyle A. Mating systems and selection efficacy: a test using chloroplastic sequence data in Angiosperms. J Evol Biol 2014; 27:1386-99. [PMID: 24674012 DOI: 10.1111/jeb.12356] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 12/26/2022]
Abstract
Selfing is assumed to reduce selection efficacy, especially purifying selection. This can be tested using molecular data, for example by comparing the Dn/Ds ratio between selfing and outcrossing lineages. So far, little evidence of relaxed selection against weakly deleterious mutations (as inferred by a higher Dn/Ds ratio) in selfers as compared to outcrossers has been found, contrary to the pattern often observed between asexual and sexual lineages. However, few groups have been studied to date. To further test this hypothesis, we compiled and analysed chloroplastic sequence data sets in several plant groups. We found a general trend towards relaxed selection in selfers in our data sets but with weak statistical support. Simulations suggested that the results were compatible with weak-to-moderate Dn/Ds ratio differences in selfing lineages. Simple theoretical predictions also showed that the ability to detect relaxed selection in selfers could strongly depend on the distribution of the effects of deleterious mutations on fitness. Our results are compatible with a recent origin of selfing lineages whereby deleterious mutations potentially have a strong impact on population extinction or with a more ancient origin but without a marked effect of deleterious mutations on the extinction dynamics.
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Affiliation(s)
- S Glémin
- Institut des Sciences de l'Evolution de Montpellier, UMR CNRS 5554, Montpellier, France
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14
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Pitino M, Hogenhout SA. Aphid protein effectors promote aphid colonization in a plant species-specific manner. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:130-9. [PMID: 23035913 DOI: 10.1094/mpmi-07-12-0172-fi] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Microbial pathogens and pests produce effectors to modulate host processes. Aphids are phloem-feeding insects, which introduce effectors via saliva into plant cells. However, it is not known if aphid effectors have adapted to modulate processes in specific plant species. Myzus persicae is a polyphagous insect that colonizes Arabidopsis thaliana and Nicotiana benthamiana, while the pea aphid Acyrthosiphon pisum specializes on colonizing plant species of the family Fabaceae. We found that M. persicae reproduction increased on transgenic Arabidopsis, producing the M. persicae effectors C002, PIntO1 (Mp1), and PIntO2 (Mp2), whereas reproduction of M. persicae did not increase on Arabidopsis producing the A. pisum orthologs of these three proteins. Plant-mediated RNA interference experiments showed that c002- and PIntO2-silenced M. persicae produce less progeny on Arabidopsis and N. benthamiana than nonsilenced aphids. Orthologs of c002, PIntO1, and PIntO2 were identified in multiple aphid species with dissimilar plant host ranges. We revealed high nonsynonymous versus synonymous nucleotide substitution rates within the effector orthologs, indicating that the effectors are fast evolving. Application of maximum likelihood methods identified specific sites with high probabilities of being under positive selection in PIntO1, whereas those of C002 and PIntO2 may be located in alignment gaps. In support of the latter, a M. persicae c002 mutant without the NDNQGEE repeat region, which overlaps with an alignment gap in C002, does not promote M. persicae colonization on Arabidopsis. Taken together, these results provide evidence that aphid effectors are under positive selection to promote aphid colonization on specific plant species.
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Affiliation(s)
- Marco Pitino
- The John Innes Centre, Norwich Research Park, Norwich, UK
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15
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Wilton PR, Sloan DB, Logsdon JM, Doddapaneni H, Neiman M. Characterization of transcriptomes from sexual and asexual lineages of a New Zealand snail (Potamopyrgus antipodarum). Mol Ecol Resour 2012; 13:289-94. [PMID: 23280235 DOI: 10.1111/1755-0998.12051] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 11/12/2012] [Accepted: 11/19/2012] [Indexed: 10/27/2022]
Abstract
Understanding the evolution and maintenance of sexual reproduction is one of the central challenges of evolutionary biology, yet we know very little about how sex influences molecular evolution. The New Zealand freshwater snail Potamopyrgus antipodarum is ideally suited to address this knowledge gap because obligately sexual individuals often coexist with multiple independently derived obligately asexual lineages. This unusual situation allows direct comparisons both between sexual and asexual P. antipodarum and across populations that differ in the relative frequency of sexual individuals. As such, P. antipodarum has received a great deal of attention as a model system for the maintenance of sex in nature and is also used as a model for environmental toxicology and biological invasions. Molecular genetic resources for P. antipodarum will thus be useful to investigators in a variety of biological fields. We used 454 sequencing of cDNA libraries to generate transcriptomes from two sexual and two asexual P. antipodarum lineages. A de novo assembly of 116.7 Mb of sequence reads produced 41 396 contigs, and sequence similarity-based Gene Ontology annotations were obtained for 3740 contigs. We detected 408 315 SNP loci and 7315 microsatellite loci, which together represent the first genome-scale resource available for P. antipodarum. Raw 454 read sequences, contig sequences, annotation data and polymorphism data are publicly available in a searchable online database and for download at http://www.biology.uiowa.edu/neiman/transcriptome.php.
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Affiliation(s)
- Peter R Wilton
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
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