1
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Forni G, Mantovani B, Mikheyev AS, Luchetti A. Parthenogenetic Stick Insects Exhibit Signatures of Preservation in the Molecular Architecture of Male Reproduction. Genome Biol Evol 2024; 16:evae073. [PMID: 38573594 PMCID: PMC11108686 DOI: 10.1093/gbe/evae073] [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: 06/18/2023] [Revised: 03/06/2024] [Accepted: 04/02/2024] [Indexed: 04/05/2024] Open
Abstract
After the loss of a trait, theory predicts that the molecular machinery underlying its phenotypic expression should decay. Yet, empirical evidence is contrasting. Here, we test the hypotheses that (i) the molecular ground plan of a lost trait could persist due to pleiotropic effects on other traits and (ii) that gene co-expression network architecture could constrain individual gene expression. Our testing ground has been the Bacillus stick insect species complex, which contains close relatives that are either bisexual or parthenogenetic. After the identification of genes expressed in male reproductive tissues in a bisexual species, we investigated their gene co-expression network structure in two parthenogenetic species. We found that gene co-expression within the male gonads was partially preserved in parthenogens. Furthermore, parthenogens did not show relaxed selection on genes upregulated in male gonads in the bisexual species. As these genes were mostly expressed in female gonads, this preservation could be driven by pleiotropic interactions and an ongoing role in female reproduction. Connectivity within the network also played a key role, with highly connected-and more pleiotropic-genes within male gonad also having a gonad-biased expression in parthenogens. Our findings provide novel insight into the mechanisms which could underlie the production of rare males in parthenogenetic lineages; more generally, they provide an example of the cryptic persistence of a lost trait molecular architecture, driven by gene pleiotropy on other traits and within their co-expression network.
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Affiliation(s)
- Giobbe Forni
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, Bologna, Italy
| | - Barbara Mantovani
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, Bologna, Italy
| | - Alexander S Mikheyev
- Research School of Biology, Australian National University, 2600 Canberra, ACT, Australia
| | - Andrea Luchetti
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, Bologna, Italy
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2
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Valim HF, Grande FD, Wong ELY, Schmitt I. Circadian clock- and temperature-associated genes contribute to overall genomic differentiation along elevation in lichenized fungi. Mol Ecol 2024; 33:e17252. [PMID: 38146927 DOI: 10.1111/mec.17252] [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: 04/25/2023] [Revised: 11/24/2023] [Accepted: 12/11/2023] [Indexed: 12/27/2023]
Abstract
Circadian regulation is linked to local environmental adaptation, and many species with broad climatic niches display variation in circadian genes. Here, we hypothesize that lichenizing fungi occupying different climate zones tune their metabolism to local environmental conditions with the help of their circadian systems. We study two species of the genus Umbilicaria occupying similar climatic niches (Mediterranean and the cold temperate) in different continents. Using homology to Neurospora crassa genes, we identify gene sets associated with circadian rhythms (11 core, 39 peripheral genes) as well as temperature response (37 genes). Nucleotide diversity of these genes is significantly correlated with mean annual temperature, minimum temperature of the coldest month and mean temperature of the coldest quarter. Furthermore, we identify altitudinal clines in allele frequencies in several non-synonymous substitutions in core clock components, for example, white collar-like, frh-like and various ccg-like genes. A dN/dS approach revealed a few significant peripheral clock- and temperature-associated genes (e.g. ras-1-like, gna-1-like) that may play a role in fine-tuning the circadian clock and temperature-response machinery. An analysis of allele frequency changes demonstrated the strongest evidence for differentiation above the genomic background in the clock-associated genes in U. pustulata. These results highlight the likely relevance of the circadian clock in environmental adaptation, particularly frost tolerance, of lichens. Whether or not the fungal clock modulates the symbiotic interaction within the lichen consortium remains to be investigated. We corroborate the finding of genetic variation in clock components along altitude-not only latitude-as has been reported in other species.
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Affiliation(s)
- Henrique F Valim
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt am Main, Germany
| | - Francesco Dal Grande
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt am Main, Germany
- Department of Biology, University of Padova, Padua, Italy
| | - Edgar L Y Wong
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt am Main, Germany
| | - Imke Schmitt
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt am Main, Germany
- Institute of Ecology, Evolution and Diversity, Goethe University Frankfurt, Frankfurt am Main, Germany
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3
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Miller SM, Stuart KC, Burke NW, Rollins LA, Bonduriansky R. Genetic and Phenotypic Consequences of Local Transitions between Sexual and Parthenogenetic Reproduction in the Wild. Am Nat 2024; 203:73-91. [PMID: 38207137 DOI: 10.1086/727511] [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] [Indexed: 01/13/2024]
Abstract
AbstractTransitions from sexual to asexual reproduction have occurred in numerous lineages, but it remains unclear why asexual populations rarely persist. In facultatively parthenogenetic animals, all-female populations can arise when males are absent or become extinct, and such populations could help to understand the genetic and phenotypic changes that occur in the initial stages of transitions to asexuality. We investigated a naturally occurring spatial mosaic of mixed-sex and all-female populations of the facultatively parthenogenetic Australian phasmid Megacrania batesii. Analysis of single-nucleotide polymorphisms indicated multiple independent transitions between reproductive modes. All-female populations had much lower heterozygosity and allelic diversity than mixed-sex populations, but we found few consistent differences in fitness-related traits between population types. All-female populations exhibited more frequent and severe deformities in their (flight-incapable) wings but did not show higher rates of appendage loss. All-female populations also harbored more ectoparasites in swamp (but not beach) habitats. Reproductive mode explained little variation in female body size, fecundity, or egg hatch rate. Our results suggest that transitions to parthenogenetic reproduction can lead to dramatic genetic changes with little immediate effect on performance. All-female M. batesii populations appear to consist of high-fitness genotypes that might be able to thrive for many generations in relatively constant and benign environments but could be vulnerable to environmental challenges, such as increased parasite abundance.
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4
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Ceron-Noriega A, Schoonenberg VAC, Butter F, Levin M. AlexandrusPS: A User-Friendly Pipeline for the Automated Detection of Orthologous Gene Clusters and Subsequent Positive Selection Analysis. Genome Biol Evol 2023; 15:evad187. [PMID: 37831426 PMCID: PMC10612477 DOI: 10.1093/gbe/evad187] [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: 07/03/2023] [Revised: 09/26/2023] [Accepted: 10/06/2023] [Indexed: 10/14/2023] Open
Abstract
The detection of adaptive selection in a system approach considering all protein-coding genes allows for the identification of mechanisms and pathways that enabled adaptation to different environments. Currently, available programs for the estimation of positive selection signals can be divided into two groups. They are either easy to apply but can analyze only one gene family at a time, restricting system analysis; or they can handle larger cohorts of gene families, but require considerable prerequisite data such as orthology associations, codon alignments, phylogenetic trees, and proper configuration files. All these steps require extensive computational expertise, restricting this endeavor to specialists. Here, we introduce AlexandrusPS, a high-throughput pipeline that overcomes technical challenges when conducting transcriptome-wide positive selection analyses on large sets of nucleotide and protein sequences. The pipeline streamlines 1) the execution of an accurate orthology prediction as a precondition for positive selection analysis, 2) preparing and organizing configuration files for CodeML, 3) performing positive selection analysis using CodeML, and 4) generating an output that is easy to interpret, including all maximum likelihood and log-likelihood test results. The only input needed from the user is the CDS and peptide FASTA files of proteins of interest. The pipeline is provided in a Docker image, requiring no program or module installation, enabling the application of the pipeline in any computing environment. AlexandrusPS and its documentation are available via GitHub (https://github.com/alejocn5/AlexandrusPS).
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Affiliation(s)
- Alejandro Ceron-Noriega
- Institute of Molecular Biology (IMB), Quantitative Proteomics, Mainz, Germany
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University Mainz, Department of Human Genetics, Mainz, Germany
| | - Vivien A C Schoonenberg
- Institute of Molecular Biology (IMB), Quantitative Proteomics, Mainz, Germany
- Present address: Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
- Present address: Molecular Pathology Unit and Center for Cancer Research, Massachusetts General Hospital, Department of Pathology, Harvard Medical School, Boston, Massachusetts, USA.
| | - Falk Butter
- Institute of Molecular Biology (IMB), Quantitative Proteomics, Mainz, Germany
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institute, Greifswald, Germany
| | - Michal Levin
- Institute of Molecular Biology (IMB), Quantitative Proteomics, Mainz, Germany
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5
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Haider M, Schilling MP, Moest MH, Steiner FM, Schlick‐Steiner BC, Arthofer W. Evolutionary history of an Alpine Archaeognath ( Machilis pallida): Insights from different variant. Ecol Evol 2023; 13:e10227. [PMID: 37404697 PMCID: PMC10316371 DOI: 10.1002/ece3.10227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 05/31/2023] [Accepted: 06/09/2023] [Indexed: 07/06/2023] Open
Abstract
Reconstruction of species histories is a central aspect of evolutionary biology. Patterns of genetic variation within and among populations can be leveraged to elucidate evolutionary processes and demographic histories. However, interpreting genetic signatures and unraveling the contributing processes can be challenging, in particular for non-model organisms with complex reproductive modes and genome organization. One way forward is the combined consideration of patterns revealed by different molecular markers (nuclear vs. mitochondrial) and types of variants (common vs. rare) that differ in their age, mode, and rate of evolution. Here, we applied this approach to RNAseq data generated for Machilis pallida (Archaeognatha), an Alpine jumping bristletail considered parthenogenetic and triploid. We generated de novo transcriptome and mitochondrial assemblies to obtain high-density data to investigate patterns of mitochondrial and common and rare nuclear variation in 17 M. pallida individuals sampled from all known populations. We find that the different variant types capture distinct aspects of the evolutionary history and discuss the observed patterns in the context of parthenogenesis, polyploidy, and survival during glaciation. This study highlights the potential of different variant types to gain insights into evolutionary scenarios even from challenging but often available data and the suitability of M. pallida and the genus Machilis as a study system for the evolution of sexual strategies and polyploidization during environmental change. We also emphasize the need for further research which will be stimulated and facilitated by these newly generated resources and insights.
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Affiliation(s)
- Marlene Haider
- Department of Ecology, Molecular Ecology GroupUniversity of InnsbruckInnsbruckAustria
| | - Martin P. Schilling
- Department of Ecology, Molecular Ecology GroupUniversity of InnsbruckInnsbruckAustria
| | - Markus H. Moest
- Department of Ecology, Molecular Ecology GroupUniversity of InnsbruckInnsbruckAustria
| | - Florian M. Steiner
- Department of Ecology, Molecular Ecology GroupUniversity of InnsbruckInnsbruckAustria
| | | | - Wolfgang Arthofer
- Department of Ecology, Molecular Ecology GroupUniversity of InnsbruckInnsbruckAustria
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6
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Forni G, Mikheyev AS, Luchetti A, Mantovani B. Gene transcriptional profiles in gonads of Bacillus taxa (Phasmida) with different cytological mechanisms of automictic parthenogenesis. ZOOLOGICAL LETTERS 2022; 8:14. [PMID: 36435814 PMCID: PMC9701443 DOI: 10.1186/s40851-022-00197-z] [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: 03/21/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
The evolution of automixis - i.e., meiotic parthenogenesis - requires several features, including ploidy restoration after meiosis and maintenance of fertility. Characterizing the relative contribution of novel versus pre-existing genes and the similarities in their expression and sequence evolution is fundamental to understand the evolution of reproductive novelties. Here we identify gonads-biased genes in two Bacillus automictic stick-insects and compare their expression profile and sequence evolution with a bisexual congeneric species. The two parthenogens restore ploidy through different cytological mechanisms: in Bacillus atticus, nuclei derived from the first meiotic division fuse to restore a diploid egg nucleus, while in Bacillus rossius, diploidization occurs in some cells of the haploid blastula through anaphase restitution. Parthenogens' gonads transcriptional program is found to be largely assembled from genes that were already present before the establishment of automixis. The three species transcriptional profiles largely reflect their phyletic relationships, yet we identify a shared core of genes with gonad-biased patterns of expression in parthenogens which are either male gonads-biased in the sexual species or are not differentially expressed there. At the sequence level, just a handful of gonads-biased genes were inferred to have undergone instances of positive selection exclusively in the parthenogen species. This work is the first to explore the molecular underpinnings of automixis in a comparative framework: it delineates how reproductive novelties can be sustained by genes whose origin precedes the establishment of the novelty itself and shows that different meiotic mechanisms of reproduction can be associated with a shared molecular ground plan.
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Affiliation(s)
- Giobbe Forni
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, 40126, Bologna, Italy
- Dip. Scienze Agrarie e Ambientali, University of Milano, Milano, Italy
| | - Alexander S Mikheyev
- Australian National University, ACT, Canberra, 2600, Australia
- Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan
| | - Andrea Luchetti
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, 40126, Bologna, Italy.
| | - Barbara Mantovani
- Dip. Scienze Biologiche, Geologiche e Ambientali (BiGeA), University of Bologna, 40126, Bologna, Italy
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7
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Maldonado JA, Firneno TJ, Hall AS, Fujita MK. Parthenogenesis doubles the rate of amino acid substitution in whiptail mitochondria. Evolution 2022; 76:1434-1442. [PMID: 35580923 DOI: 10.1111/evo.14509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 03/10/2022] [Accepted: 03/21/2022] [Indexed: 01/21/2023]
Abstract
Sexual reproduction is ubiquitous in the natural world, suggesting that sex must have extensive benefits to overcome the cost of males compared to asexual reproduction. One hypothesized advantage of sex with strong theoretical support is that sex plays a role in removing deleterious mutations from the genome. Theory predicts that transitions to asexuality should lead to the suppression of recombination and segregation and, in turn, weakened natural selection, allowing for the accumulation of slightly deleterious mutations. We tested this prediction by estimating the dN/dS ratios in asexual vertebrate lineages in the genus Aspidoscelis using whole mitochondrial genomes from seven asexual and five sexual species. We found higher dN/dS ratios in asexual Aspidoscelis species, indicating that asexual whiptails accumulate nonsynonymous substitutions due to weaker purifying selection. Additionally, we estimated nucleotide diversity and found that asexuals harbor significantly less diversity. Thus, despite their recent origins, slightly deleterious mutations accumulated rapidly enough in asexual lineages to be detected. We provide empirical evidence to corroborate the connection between asexuality and increased amino acid substitutions in asexual vertebrate lineages.
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Affiliation(s)
- Jose A Maldonado
- Amphibian and Reptile Diversity Research Center, Department of Biology, The University of Texas, Arlington, Texas, USA
| | - Thomas J Firneno
- Amphibian and Reptile Diversity Research Center, Department of Biology, The University of Texas, Arlington, Texas, USA
| | - Alexander S Hall
- Amphibian and Reptile Diversity Research Center, Department of Biology, The University of Texas, Arlington, Texas, USA
| | - Matthew K Fujita
- Amphibian and Reptile Diversity Research Center, Department of Biology, The University of Texas, Arlington, Texas, USA
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8
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Ohtsuki H, Norimatsu H, Makino T, Urabe J. Invasions of an obligate asexual daphnid species support the nearly neutral theory. Sci Rep 2022; 12:7305. [PMID: 35508526 PMCID: PMC9068809 DOI: 10.1038/s41598-022-11218-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/20/2022] [Indexed: 11/09/2022] Open
Abstract
To verify the "nearly neutral theory (NNT)," the ratio of nonsynonymous to synonymous substitutions (dN/dS) was compared among populations of different species. To determine the validity of NNT, however, populations that are genetically isolated from each other but share the same selection agents and differ in size should be compared. Genetically different lineages of obligate asexual Daphnia pulex invading Japan from North America are an ideal example as they satisfy these prerequisites. Therefore, we analyzed the whole-genome sequences of 18 genotypes, including those of the two independently invaded D. pulex lineages (JPN1 and JPN2) and compared the dN/dS ratio between the lineages. The base substitution rate of each genotype demonstrated that the JPN1 lineage having a larger distribution range diverged earlier and thus was older than the JPN2 lineage. Comparisons of the genotypes within lineages revealed that changes in dN/dS occurred after the divergence and were larger in the younger lineage, JPN2. These results imply that the JPN1 lineage has been more effectively subjected to purification selections, while slightly deteriorating mutations are less purged in JPN2 with smaller population size. Altogether, the lineage-specific difference in the dN/dS ratio for the obligate asexual D. pulex was well explained by the NNT.
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Affiliation(s)
- Hajime Ohtsuki
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Hirotomo Norimatsu
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Takashi Makino
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Jotaro Urabe
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
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9
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Jaron KS, Parker DJ, Anselmetti Y, Tran Van P, Bast J, Dumas Z, Figuet E, François CM, Hayward K, Rossier V, Simion P, Robinson-Rechavi M, Galtier N, Schwander T. Convergent consequences of parthenogenesis on stick insect genomes. SCIENCE ADVANCES 2022; 8:eabg3842. [PMID: 35196080 PMCID: PMC8865771 DOI: 10.1126/sciadv.abg3842] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The shift from sexual reproduction to parthenogenesis has occurred repeatedly in animals, but how the loss of sex affects genome evolution remains poorly understood. We generated reference genomes for five independently evolved parthenogenetic species in the stick insect genus Timema and their closest sexual relatives. Using these references and population genomic data, we show that parthenogenesis results in an extreme reduction of heterozygosity and often leads to genetically uniform populations. We also find evidence for less effective positive selection in parthenogenetic species, suggesting that sex is ubiquitous in natural populations because it facilitates fast rates of adaptation. Parthenogenetic species did not show increased transposable element (TE) accumulation, likely because there is little TE activity in the genus. By using replicated sexual-parthenogenetic comparisons, our study reveals how the absence of sex affects genome evolution in natural populations, providing empirical support for the negative consequences of parthenogenesis as predicted by theory.
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Affiliation(s)
- Kamil S. Jaron
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
- Corresponding author. (D.J.P.); (K.S.J.); (T.S.)
| | - Darren J. Parker
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Corresponding author. (D.J.P.); (K.S.J.); (T.S.)
| | | | - Patrick Tran Van
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Zoé Dumas
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Emeric Figuet
- ISEM—Institut des Sciences de l’Evolution, Montpellier, France
| | | | - Keith Hayward
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Victor Rossier
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Paul Simion
- ISEM—Institut des Sciences de l’Evolution, Montpellier, France
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Nicolas Galtier
- ISEM—Institut des Sciences de l’Evolution, Montpellier, France
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Corresponding author. (D.J.P.); (K.S.J.); (T.S.)
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10
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Janko K, Bartoš O, Kočí J, Roslein J, Drdová EJ, Kotusz J, Eisner J, Mokrejš M, Štefková-Kašparová E. Genome Fractionation and Loss of Heterozygosity in Hybrids and Polyploids: Mechanisms, Consequences for Selection, and Link to Gene Function. Mol Biol Evol 2021; 38:5255-5274. [PMID: 34410426 PMCID: PMC8662595 DOI: 10.1093/molbev/msab249] [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] [Indexed: 12/28/2022] Open
Abstract
Hybridization and genome duplication have played crucial roles in the evolution of many animal and plant taxa. The subgenomes of parental species undergo considerable changes in hybrids and polyploids, which often selectively eliminate segments of one subgenome. However, the mechanisms underlying these changes are not well understood, particularly when the hybridization is linked with asexual reproduction that opens up unexpected evolutionary pathways. To elucidate this problem, we compared published cytogenetic and RNAseq data with exome sequences of asexual diploid and polyploid hybrids between three fish species; Cobitis elongatoides, C. taenia, and C. tanaitica. Clonal genomes remained generally static at chromosome-scale levels but their heterozygosity gradually deteriorated at the level of individual genes owing to allelic deletions and conversions. Interestingly, the impact of both processes varies among animals and genomic regions depending on ploidy level and the properties of affected genes. Namely, polyploids were more tolerant to deletions than diploid asexuals where conversions prevailed, and genomic restructuring events accumulated preferentially in genes characterized by high transcription levels and GC-content, strong purifying selection and specific functions like interacting with intracellular membranes. Although hybrids were phenotypically more similar to C. taenia, we found that they preferentially retained C. elongatoides alleles. This demonstrates that favored subgenome is not necessarily the transcriptionally dominant one. This study demonstrated that subgenomes in asexual hybrids and polyploids evolve under a complex interplay of selection and several molecular mechanisms whose efficiency depends on the organism's ploidy level, as well as functional properties and parental ancestry of the genomic region.
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Affiliation(s)
- Karel Janko
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Oldřich Bartoš
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Kočí
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Jan Roslein
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Edita Janková Drdová
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jan Kotusz
- Museum of Natural History, University of Wroclaw, Wroclaw, Poland
| | - Jan Eisner
- Department of Mathematics, Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice, Czech Republic
| | - Martin Mokrejš
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- IT4Innovations, VŠB—Technical University of Ostrava, Ostrava-Poruba, Czech Republic
| | - Eva Štefková-Kašparová
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Liběchov, Czech Republic
- Department of Genetics and Breeding, FAFNR, Czech University of Life Sciences Prague, Czech Republic
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11
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Kolařík M, Wei IC, Hsieh SY, Piepenbring M, Kirschner R. Nucleotide composition bias of rDNA sequences as a source of phylogenetic artifacts in Basidiomycota—a case of a new lineage of a uredinicolous Ramularia-like anamorph with affinities to Ustilaginomycotina. Mycol Prog 2021. [DOI: 10.1007/s11557-021-01749-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Charlesworth B, Jensen JD. Effects of Selection at Linked Sites on Patterns of Genetic Variability. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2021; 52:177-197. [PMID: 37089401 PMCID: PMC10120885 DOI: 10.1146/annurev-ecolsys-010621-044528] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Patterns of variation and evolution at a given site in a genome can be strongly influenced by the effects of selection at genetically linked sites. In particular, the recombination rates of genomic regions correlate with their amount of within-population genetic variability, the degree to which the frequency distributions of DNA sequence variants differ from their neutral expectations, and the levels of adaptation of their functional components. We review the major population genetic processes that are thought to lead to these patterns, focusing on their effects on patterns of variability: selective sweeps, background selection, associative overdominance, and Hill–Robertson interference among deleterious mutations. We emphasize the difficulties in distinguishing among the footprints of these processes and disentangling them from the effects of purely demographic factors such as population size changes. We also discuss how interactions between selective and demographic processes can significantly affect patterns of variability within genomes.
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Affiliation(s)
- Brian Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Jeffrey D. Jensen
- School of Life Sciences, Arizona State University, Tempe, Arizona 85281, USA
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13
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Barley AJ, Cordes JE, Walker JM, Thomson RC. Genetic diversity and the origins of parthenogenesis in the teiid lizard Aspidoscelis laredoensis. Mol Ecol 2021; 31:266-278. [PMID: 34614250 DOI: 10.1111/mec.16213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 09/14/2021] [Accepted: 09/30/2021] [Indexed: 01/25/2023]
Abstract
Unisexual vertebrates typically form through hybridization events between sexual species in which reproductive mode transitions occur in the hybrid offspring. This evolutionary history is thought to have important consequences for the ecology of unisexual lineages and their interactions with congeners in natural communities. However, these consequences have proven challenging to study owing to uncertainty about patterns of population genetic diversity in unisexual lineages. Of particular interest is resolving the contribution of historical hybridization events versus post formational mutation to patterns of genetic diversity in nature. Here we use restriction site associated DNA genotyping to evaluate genetic diversity and demographic history in Aspidoscelis laredoensis, a diploid unisexual lizard species from the vicinity of the Rio Grande River in southern Texas and northern Mexico. The sexual progenitor species from which one or more lineages are derived also occur in the Rio Grande Valley region, although patterns of distribution across individual sites are quite variable. Results from population genetic and phylogenetic analyses resolved the major axes of genetic variation in this species and highlight how these match predictions based on historical patterns of hybridization. We also found discordance between results of demographic modelling using different statistical approaches with the genomic data. We discuss these insights within the context of the ecological and evolutionary mechanisms that generate and maintain lineage diversity in unisexual species. As one of the most dynamic, intriguing, and geographically well investigated groups of whiptail lizards, these species hold substantial promise for future studies on the constraints of diversification in unisexual vertebrates.
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Affiliation(s)
- Anthony J Barley
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'I, USA
| | - James E Cordes
- Division of Sciences and Mathematics, Louisiana State University Eunice, Eunice, Louisiana, USA
| | - James M Walker
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USA
| | - Robert C Thomson
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'I, USA
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14
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Forni G, Ruggieri AA, Piccinini G, Luchetti A. BASE: A novel workflow to integrate nonubiquitous genes in comparative genomics analyses for selection. Ecol Evol 2021; 11:13029-13035. [PMID: 34646450 PMCID: PMC8495783 DOI: 10.1002/ece3.7959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/29/2021] [Accepted: 07/12/2021] [Indexed: 11/07/2022] Open
Abstract
Inferring the selective forces that orthologous genes underwent across different lineages can help us understand the evolutionary processes that have shaped their extant diversity and the phenotypes they underlie. The most widespread metric to estimate the selection regimes of coding genes-across sites and phylogenies-is the ratio of nonsynonymous to synonymous substitutions (dN/dS, also known as ω). Nowadays, modern sequencing technologies and the large amount of already available sequence data allow the retrieval of thousands of orthologous genes across large numbers of species. Nonetheless, the tools available to explore selection regimes are not designed to automatically process all genes, and their practical usage is often restricted to the single-copy ones which are found across all species considered (i.e., ubiquitous genes). This approach limits the scale of the analysis to a fraction of single-copy genes, which can be as low as an order of magnitude in respect to those which are not consistently found in all species considered (i.e., nonubiquitous genes). Here, we present a workflow named BASE that-leveraging the CodeML framework-eases the inference and interpretation of gene selection regimes in the context of comparative genomics. Although a number of bioinformatics tools have already been developed to facilitate this kind of analyses, BASE is the first to be specifically designed to allow the integration of nonubiquitous genes in a straightforward and reproducible manner. The workflow-along with all relevant documentation-is available at github.com/for-giobbe/BASE.
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Affiliation(s)
- Giobbe Forni
- BiGeA Department University of Bologna Bologna Italy
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15
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Brandt A, Tran Van P, Bluhm C, Anselmetti Y, Dumas Z, Figuet E, François CM, Galtier N, Heimburger B, Jaron KS, Labédan M, Maraun M, Parker DJ, Robinson-Rechavi M, Schaefer I, Simion P, Scheu S, Schwander T, Bast J. Haplotype divergence supports long-term asexuality in the oribatid mite Oppiella nova. Proc Natl Acad Sci U S A 2021; 118:e2101485118. [PMID: 34535550 PMCID: PMC8463897 DOI: 10.1073/pnas.2101485118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2021] [Indexed: 12/05/2022] Open
Abstract
Sex strongly impacts genome evolution via recombination and segregation. In the absence of these processes, haplotypes within lineages of diploid organisms are predicted to accumulate mutations independently of each other and diverge over time. This so-called "Meselson effect" is regarded as a strong indicator of the long-term evolution under obligate asexuality. Here, we present genomic and transcriptomic data of three populations of the asexual oribatid mite species Oppiella nova and its sexual relative Oppiella subpectinata We document strikingly different patterns of haplotype divergence between the two species, strongly supporting Meselson effect-like evolution and long-term asexuality in O. nova: I) variation within individuals exceeds variation between populations in O. nova but vice versa in O. subpectinata; II) two O. nova sublineages feature a high proportion of lineage-specific heterozygous single-nucleotide polymorphisms (SNPs), indicating that haplotypes continued to diverge after lineage separation; III) the deepest split in gene trees generally separates the two haplotypes in O. nova, but populations in O. subpectinata; and IV) the topologies of the two haplotype trees match each other. Our findings provide positive evidence for the absence of canonical sex over evolutionary time in O. nova and suggest that asexual oribatid mites can escape the dead-end fate usually associated with asexual lineages.
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Affiliation(s)
- Alexander Brandt
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany;
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Patrick Tran Van
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Christian Bluhm
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany
- Abteilung Boden und Umwelt, Forstliche Versuchs- und Forschungsanstalt Baden-Wuerttemberg, 79100 Freiburg, Germany
| | - Yoann Anselmetti
- Group Phylogeny and Molecular Evolution, Institut des Sciences de l'Evolution de Montpellier, 34090 Montpellier, France
- CoBIUS Lab, Department of Computer Science, University of Sherbrooke, Sherbrooke, QC J1K2R1, Canada
| | - Zoé Dumas
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Emeric Figuet
- Group Phylogeny and Molecular Evolution, Institut des Sciences de l'Evolution de Montpellier, 34090 Montpellier, France
| | - Clémentine M François
- Group Phylogeny and Molecular Evolution, Institut des Sciences de l'Evolution de Montpellier, 34090 Montpellier, France
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés, École Nationale des Travaux Publics de l'État, Université Claude Bernard Lyon 1, 69622 Villeurbanne, France
| | - Nicolas Galtier
- Group Phylogeny and Molecular Evolution, Institut des Sciences de l'Evolution de Montpellier, 34090 Montpellier, France
| | - Bastian Heimburger
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany
| | - Kamil S Jaron
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
- Group Evolutionary Bioinformatics, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, United Kingdom
| | - Marjorie Labédan
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Mark Maraun
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany
| | - Darren J Parker
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
- Group Evolutionary Bioinformatics, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
- Group Evolutionary Bioinformatics, Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Ina Schaefer
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany
| | - Paul Simion
- Group Phylogeny and Molecular Evolution, Institut des Sciences de l'Evolution de Montpellier, 34090 Montpellier, France
- Laboratory of Evolutionary Genetics and Ecology, Unit in Environmental and Evolutionary Biology, Université de Namur, 5000 Namur, Belgium
| | - Stefan Scheu
- Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, University of Goettingen, 37073 Goettingen, Germany
- Section Biodiversity and Ecology, Centre of Biodiversity and Sustainable Land Use, 37073 Goettingen, Germany
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
- Institute for Zoology, University of Cologne, 50674 Cologne, Germany
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16
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Nozaki T, Suetsugu K, Sato K, Sato R, Takagi T, Funaki S, Ito K, Kurita K, Isagi Y, Kaneko S. Development of microsatellite markers for the geographically parthenogenetic stick insect Phraortes elongatus (Insecta: Phasmatodea). Genes Genet Syst 2021; 96:199-203. [PMID: 34483152 DOI: 10.1266/ggs.21-00022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Many plant and animal species exhibit geographic parthenogenesis, wherein unisexual (= parthenogenetic) lineages are more common in their marginal habitats such as high latitude or altitudes than their closely related bisexual counterparts. The Japanese stick insect, Phraortes elongatus (Thunberg) (Insecta: Phasmatodea), is known as a geographically parthenogenetic species due to the existence of both bisexual and unisexual populations. Here, we developed microsatellite markers to infer the genetic variation among populations of P. elongatus. Totally, 13 primer pairs were developed for the species, and they were tested on 47 samples collected from both a bisexual population and a unisexual population. All 13 loci were polymorphic in the bisexual population, whereas no loci were polymorphic in the unisexual population. The loss of variation in the unisexual population implies automixis with terminal fusion or gamete duplication as the mode of parthenogenesis. The markers developed in this study will be helpful for further comprehensive analysis of the genetic diversity and gene flow between bisexual and parthenogenetic lineages of P. elongatus.
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Affiliation(s)
- Tomonari Nozaki
- Center for the Development of New Model Organisms, National Institute for Basic Biology
| | - Kenji Suetsugu
- Department of Biology, Graduate School of Science, Kobe University
| | - Kai Sato
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University
| | - Ryuta Sato
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University
| | - Toshihito Takagi
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University
| | - Shoichi Funaki
- Faculty of Agriculture and Marine Science, Kochi University
| | - Katsura Ito
- Faculty of Agriculture and Marine Science, Kochi University
| | | | - Yuji Isagi
- Graduate School of Agriculture, Kyoto University
| | - Shingo Kaneko
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University
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17
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McElroy KE, Müller S, Lamatsch DK, Bankers L, Fields PD, Jalinsky JR, Sharbrough J, Boore JL, Logsdon JM, Neiman M. Asexuality Associated with Marked Genomic Expansion of Tandemly Repeated rRNA and Histone Genes. Mol Biol Evol 2021; 38:3581-3592. [PMID: 33885820 PMCID: PMC8382920 DOI: 10.1093/molbev/msab121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
How does asexual reproduction influence genome evolution? Although is it clear that genomic structural variation is common and important in natural populations, we know very little about how one of the most fundamental of eukaryotic traits-mode of genomic inheritance-influences genome structure. We address this question with the New Zealand freshwater snail Potamopyrgus antipodarum, which features multiple separately derived obligately asexual lineages that coexist and compete with otherwise similar sexual lineages. We used whole-genome sequencing reads from a diverse set of sexual and asexual individuals to analyze genomic abundance of a critically important gene family, rDNA (the genes encoding rRNAs), that is notable for dynamic and variable copy number. Our genomic survey of rDNA in P. antipodarum revealed two striking results. First, the core histone and 5S rRNA genes occur between tandem copies of the 18S-5.8S-28S gene cluster, a unique architecture for these crucial gene families. Second, asexual P. antipodarum harbor dramatically more rDNA-histone copies than sexuals, which we validated through molecular and cytogenetic analysis. The repeated expansion of this genomic region in asexual P. antipodarum lineages following distinct transitions to asexuality represents a dramatic genome structural change associated with asexual reproduction-with potential functional consequences related to the loss of sexual reproduction.
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Affiliation(s)
- Kyle E McElroy
- Ecology, Evolutionary, and Organismal Biology, Iowa State University, Ames, IA, USA
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Stefan Müller
- Institute of Human Genetics, Munich University Hospital, Ludwig-Maximilians University, Munich, Germany
| | - Dunja K Lamatsch
- Research Department for Limnology, University of Innsbruck, Mondsee, Mondsee, Austria
| | - Laura Bankers
- Division of Infectious Diseases, University of Colorado—Anschutz Medical Campus, Aurora, CO, USA
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | | | - Joel Sharbrough
- Biology Department, New Mexico Institute of Mining and Technology, Socorro, NM, USA
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Jeffrey L Boore
- Providence St. Joseph Health and Institute for Systems Biology, Seattle, WA, USA
| | - John M Logsdon
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Maurine Neiman
- Department of Biology, University of Iowa, Iowa City, IA, USA
- Department of Gender, Women's, and Sexuality Studies, University of Iowa, Iowa City, IA, USA
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18
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Koufopanou V, Lomas S, Pronina O, Almeida P, Sampaio JP, Mousseau T, Liti G, Burt A. Population Size, Sex and Purifying Selection: Comparative Genomics of Two Sister Taxa of the Wild Yeast Saccharomyces paradoxus. Genome Biol Evol 2021; 12:1636-1645. [PMID: 33011797 PMCID: PMC7533043 DOI: 10.1093/gbe/evaa141] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2020] [Indexed: 12/16/2022] Open
Abstract
This study uses population genomic data to estimate demographic and selection parameters in two sister lineages of the wild yeast Saccharomyces paradoxus and compare their evolution. We first estimate nucleotide and recombinational diversities in each of the two lineages to infer their population size and frequency of sex and then analyze the rate of mutation accumulation since divergence from their inferred common ancestor to estimate the generation time and efficacy of selection. We find that one of the lineages has significantly higher silent nucleotide diversity and lower linkage disequilibrium, indicating a larger population with more frequent sexual generations. The same lineage also shows shorter generation time and higher efficacy of purifying selection, the latter consistent with the finding of larger population size and more frequent sex. Similar analyses are also performed on the ancestries of individual strains within lineages and we find significant differences between strains implying variation in rates of mitotic cell divisions. Our sample includes some strains originating in the Chernobyl nuclear-accident exclusion zone, which has been subjected to high levels of radiation for nearly 30 years now. We find no evidence, however, for increased rates of mutation. Finally, there is a positive correlation between rates of mutation accumulation and length of growing period, as measured by latitude of the place of origin of strains. Our study illustrates the power of genomic analyses in estimating population and life history parameters and testing predictions based on population genetic theory.
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Affiliation(s)
- Vassiliki Koufopanou
- Department of Life Sciences, Imperial College London, Ascot, Berks, United Kingdom
| | - Susan Lomas
- Department of Life Sciences, Imperial College London, Ascot, Berks, United Kingdom
| | - Olga Pronina
- Institute of Cell Biology and Genetic Engineering, NAS of Ukraine, Kyiv, Ukraine
| | - Pedro Almeida
- Department of Genetics, Evolution & Environment, University College London, United Kingdom
| | - Jose Paulo Sampaio
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Portugal
| | | | - Gianni Liti
- CNRS, INSERM, IRCAN, Universite Cote d' Azur, Nice, France
| | - Austin Burt
- Department of Life Sciences, Imperial College London, Ascot, Berks, United Kingdom
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19
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Barley AJ, Reeder TW, Nieto-Montes de Oca A, Cole CJ, Thomson RC. A New Diploid Parthenogenetic Whiptail Lizard from Sonora, Mexico, Is the "Missing Link" in the Evolutionary Transition to Polyploidy. Am Nat 2021; 198:295-309. [PMID: 34260872 DOI: 10.1086/715056] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractTransitions between sexual and unisexual reproductive modes have significant consequences for the evolutionary trajectories of species. These transitions have occurred numerous times in vertebrates and are frequently mediated by hybridization events. Triploid unisexual vertebrates are thought to arise through hybridization between individuals of a diploid unisexual lineage and a sexual species, although additional evidence that confirms this mechanism is needed in numerous groups. North American whiptail lizards (Aspidoscelis) are notable for being one of the largest radiations of unisexual vertebrates, and the most diverse group of Aspidoscelis includes numerous triploid lineages that have no known diploid unisexual ancestors. This pattern of "missing" ancestors may result from the short evolutionary life span of unisexual lineages or the selective advantages of polyploidy, or it could suggest that alternative mechanisms of triploid formation are operating in nature. We leverage genomic, morphological, and karyotypic data to describe a new diploid unisexual whiptail and show that it is likely the unisexual progenitor of an extant triploid lineage, A. opatae. We also resolve patterns of polyploidization within the A. sexlineatus species group and test predictions about the phenotypic outcomes of hybridization.
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20
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Szövényi P, Gunadi A, Li FW. Charting the genomic landscape of seed-free plants. NATURE PLANTS 2021; 7:554-565. [PMID: 33820965 DOI: 10.1038/s41477-021-00888-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 02/25/2021] [Indexed: 05/02/2023]
Abstract
During the past few years several high-quality genomes has been published from Charophyte algae, bryophytes, lycophytes and ferns. These genomes have not only elucidated the origin and evolution of early land plants, but have also provided important insights into the biology of the seed-free lineages. However, critical gaps across the phylogeny remain and many new questions have been raised through comparing seed-free and seed plant genomes. Here, we review the reference genomes available and identify those that are missing in the seed-free lineages. We compare patterns of various levels of genome and epigenomic organization found in seed-free plants to those of seed plants. Some genomic features appear to be fundamentally different. For instance, hornworts, Selaginella and most liverworts are devoid of whole-genome duplication, in stark contrast to other land plants. In addition, the distribution of genes and repeats appear to be less structured in seed-free genomes than in other plants, and the levels of gene body methylation appear to be much lower. Finally, we highlight the currently available (or needed) model systems, which are crucial to further our understanding about how changes in genes translate into evolutionary novelties.
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Affiliation(s)
- Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich and Zurich-Basel Plant Science Center, Zurich, Switzerland.
| | | | - Fay-Wei Li
- Boyce Thompson Institute, Ithaca, NY, USA
- Plant Biology Section, Cornell University, Ithaca, NY, USA
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21
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Sexual Selection: Evolutionary Foundations. Anim Behav 2021. [DOI: 10.1007/978-3-030-82879-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Fujita MK, Singhal S, Brunes TO, Maldonado JA. Evolutionary Dynamics and Consequences of Parthenogenesis in Vertebrates. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-114900] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Parthenogenesis is asexual reproduction without any required participation from males and, as such, is a null model for sexual reproduction. In a comparative context, we can expand our understanding of the evolution and ecology of sex by investigating the consequences of parthenogenesis. In this review, we examine the theoretical predictions of and empirical results on the evolution of asexual reproduction in vertebrates, focusing on recent studies addressing the origins and geographic spread of parthenogenetic lineages and the genomic consequences of an asexual life history. With advances in computational methods and genome technologies, researchers are poised to make rapid and significant progress in studying the origin and evolution of parthenogenesis in vertebrates, thus providing an important perspective on understanding biodiversity patterns of both asexual and sexual populations.
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Affiliation(s)
- Matthew K. Fujita
- Amphibian and Reptile Diversity Research Center and Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, USA
| | - Sonal Singhal
- Department of Biology, California State University, Dominguez Hills, Carson, California 90747, USA
| | - Tuliana O. Brunes
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-090, Brazil
| | - Jose A. Maldonado
- Amphibian and Reptile Diversity Research Center and Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, USA
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23
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Lee YH, Kang HM, Kim MS, Lee JS, Wang M, Hagiwara A, Jeong CB, Lee JS. Multigenerational Mitigating Effects of Ocean Acidification on In Vivo Endpoints, Antioxidant Defense, DNA Damage Response, and Epigenetic Modification in an Asexual Monogonont Rotifer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:7858-7869. [PMID: 32490673 DOI: 10.1021/acs.est.0c01438] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ocean acidification (OA) is caused by changes in ocean carbon chemistry due to increased atmospheric pCO2 and is predicted to have deleterious effects on marine ecosystems. While the potential impacts of OA on many marine species have been studied, the multigenerational effects on asexual organisms remain unknown. We found that low seawater pH induced oxidative stress and DNA damage, decreasing growth rates, fecundity, and lifespans in the parental generation, whereas deleterious effects on in vivo endpoints in F1 and F2 offspring were less evident. The findings suggest that multigenerational adaptive effects play a role in antioxidant abilities and other defense mechanisms. OA-induced DNA damage, including double-strand breaks (DSBs), was fully repaired in F1 offspring of parents exposed to OA for 7 days, indicating that an adaptation mechanism may be the major driving force behind multigenerational adaptive effects. Analysis of epigenetic modification in response to OA involved examination of histone modification of DNA repair genes and a chromatin immunoprecipitation assay, as Bombus koreanus has no methylation pattern for CpG in its genome. We conclude that DSBs, DNA repair, and histone modification play important roles in multigenerational plasticity in response to OA in an asexual monogonont rotifer.
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Affiliation(s)
- Young Hwan Lee
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Hye-Min Kang
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Min-Sub Kim
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Jin-Sol Lee
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Minghua Wang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems/College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Atsushi Hagiwara
- Institute of Integrated Science and Technology, Nagasaki University, Nagasaki 852-8521, Japan
- Organization for Marine Science and Technology, Nagasaki University, Nagasaki 852-8521, Japan
| | - Chang-Bum Jeong
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
- Department of Marine Science, College of Nature Science, Incheon National University, Incheon 22012, South Korea
| | - Jae-Seong Lee
- Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
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24
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Dalziel AC, Tirbhowan S, Drapeau HF, Power C, Jonah LS, Gbotsyo YA, Dion‐Côté A. Using asexual vertebrates to study genome evolution and animal physiology: Banded ( Fundulus diaphanus) x Common Killifish ( F. heteroclitus) hybrid lineages as a model system. Evol Appl 2020; 13:1214-1239. [PMID: 32684956 PMCID: PMC7359844 DOI: 10.1111/eva.12975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 12/27/2022] Open
Abstract
Wild, asexual, vertebrate hybrids have many characteristics that make them good model systems for studying how genomes evolve and epigenetic modifications influence animal physiology. In particular, the formation of asexual hybrid lineages is a form of reproductive incompatibility, but we know little about the genetic and genomic mechanisms by which this mode of reproductive isolation proceeds in animals. Asexual lineages also provide researchers with the ability to produce genetically identical individuals, enabling the study of autonomous epigenetic modifications without the confounds of genetic variation. Here, we briefly review the cellular and molecular mechanisms leading to asexual reproduction in vertebrates and the known genetic and epigenetic consequences of the loss of sex. We then specifically discuss what is known about asexual lineages of Fundulus diaphanus x F. heteroclitus to highlight gaps in our knowledge of the biology of these clones. Our preliminary studies of F. diaphanus and F. heteroclitus karyotypes from Porter's Lake (Nova Scotia, Canada) agree with data from other populations, suggesting a conserved interspecific chromosomal arrangement. In addition, genetic analyses suggest that: (a) the same major clonal lineage (Clone A) of F. diaphanus x F. heteroclitus has remained dominant over the past decade, (b) some minor clones have also persisted, (c) new clones may have recently formed, and iv) wild clones still mainly descend from F. diaphanus ♀ x F. heteroclitus ♂ crosses (96% in 2017-2018). These data suggest that clone formation may be a relatively rare, but continuous process, and there are persistent environmental or genetic factors causing a bias in cross direction. We end by describing our current research on the genomic causes and consequences of a transition to asexuality and the potential physiological consequences of epigenetic variation.
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Affiliation(s)
| | - Svetlana Tirbhowan
- Department of BiologySaint Mary's UniversityHalifaxNSCanada
- Département de biologieUniversité de MonctonMonctonNBCanada
| | | | - Claude Power
- Département de biologieUniversité de MonctonMonctonNBCanada
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Leria L, Vila-Farré M, Álvarez-Presas M, Sánchez-Gracia A, Rozas J, Sluys R, Riutort M. Cryptic species delineation in freshwater planarians of the genus Dugesia (Platyhelminthes, Tricladida): Extreme intraindividual genetic diversity, morphological stasis, and karyological variability. Mol Phylogenet Evol 2020; 143:106496. [DOI: 10.1016/j.ympev.2019.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 04/10/2019] [Accepted: 05/17/2019] [Indexed: 01/04/2023]
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Becher H, Jackson BC, Charlesworth B. Patterns of Genetic Variability in Genomic Regions with Low Rates of Recombination. Curr Biol 2019; 30:94-100.e3. [PMID: 31866366 DOI: 10.1016/j.cub.2019.10.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/09/2019] [Accepted: 10/23/2019] [Indexed: 12/19/2022]
Abstract
The amount of DNA sequence variability in a genomic region is often positively correlated with its rate of crossing over (CO) [1-3]. This pattern is caused by selection acting on linked sites, which reduces genetic variability and biases the frequency distribution of segregating variants toward more rare variants than are expected without selection (skew). These effects may involve the spread of beneficial mutations (selective sweeps [SSWs]), the elimination of deleterious mutations (background selection [BGS]), or both, and are expected to be stronger with lower CO rates [1-3]. However, in a recent study of human populations, the skew was reduced in the lowest CO regions compared with regions with somewhat higher CO rates [4]. A low skew in very low CO regions, compared with theoretical predictions, is seen in the population genomic studies of Drosophila simulans described here and in other Drosophila species. Here, we propose an explanation for lower than expected skew in low CO regions, and validate it using computer simulations; explanations for higher skew with higher CO rates, as in D. simulans, will be explored elsewhere. Partially recessive, linked deleterious mutations can increase neutral variability when the product of the effective population size (Ne) and the selection coefficient against homozygous carriers of mutations (s) is ≤1, i.e., there is associative overdominance (AOD) rather than BGS [5]. AOD can operate in low CO regions, producing a lower skew than in its absence. This opens up a new perspective on how selection affects patterns of variability at linked sites.
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Affiliation(s)
- Hannes Becher
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
| | - Benjamin C Jackson
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Brian Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
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Sex-biased gene expression is repeatedly masculinized in asexual females. Nat Commun 2019; 10:4638. [PMID: 31604947 PMCID: PMC6789136 DOI: 10.1038/s41467-019-12659-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 09/23/2019] [Indexed: 12/21/2022] Open
Abstract
Males and females feature strikingly different phenotypes, despite sharing most of their genome. A resolution of this apparent paradox is through differential gene expression, whereby genes are expressed at different levels in each sex. This resolution, however, is likely to be incomplete, leading to conflict between males and females over the optimal expression of genes. Here we test the hypothesis that gene expression in females is constrained from evolving to its optimum level due to sexually antagonistic selection on males, by examining changes in sex-biased gene expression in five obligate asexual species of stick insect, which do not produce males. We predicted that the transcriptome of asexual females would be feminized as asexual females do not experience any sexual conflict. Contrary to our prediction we find that asexual females feature masculinized gene expression, and hypothesise that this is due to shifts in female optimal gene expression levels following the suppression of sex.
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Morgan-Richards M, Langton-Myers SS, Trewick SA. Loss and gain of sexual reproduction in the same stick insect. Mol Ecol 2019; 28:3929-3941. [PMID: 31386772 PMCID: PMC6852293 DOI: 10.1111/mec.15203] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 06/17/2019] [Accepted: 07/30/2019] [Indexed: 01/10/2023]
Abstract
The outcome of competition between different reproductive strategies within a single species can be used to infer selective advantage of the winning strategy. Where multiple populations have independently lost or gained sexual reproduction it is possible to investigate whether the advantage is contingent on local conditions. In the New Zealand stick insect Clitarchus hookeri, three populations are distinguished by recent change in reproductive strategy and we determine their likely origins. One parthenogenetic population has established in the United Kingdom and we provide evidence that sexual reproduction has been lost in this population. We identify the sexual population from which the parthenogenetic population was derived, but show that the UK females have a post‐mating barrier to fertilisation. We also demonstrate that two sexual populations have recently arisen in New Zealand within the natural range of the mtDNA lineage that otherwise characterizes parthenogenesis in this species. We infer independent origins of males at these two locations using microsatellite genotypes. In one population, a mixture of local and nonlocal alleles suggested males were the result of invasion. Males in another population were most probably the result of loss of an X chromosome that produced a male phenotype in situ. Two successful switches in reproductive strategy suggest local competitive advantage for outcrossing over parthenogenetic reproduction. Clitarchus hookeri provides remarkable evidence of repeated and rapid changes in reproductive strategy, with competitive outcomes dependent on local conditions.
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Affiliation(s)
| | | | - Steven A Trewick
- Wildlife & Ecology, Massey University, Palmerston North, New Zealand
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29
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Leria L, Vila-Farré M, Solà E, Riutort M. Outstanding intraindividual genetic diversity in fissiparous planarians (Dugesia, Platyhelminthes) with facultative sex. BMC Evol Biol 2019; 19:130. [PMID: 31221097 PMCID: PMC6587288 DOI: 10.1186/s12862-019-1440-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 05/15/2019] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Predicted genetic consequences of asexuality include high intraindividual genetic diversity (i.e., the Meselson effect) and accumulation of deleterious mutations (i.e., Muller's Ratchet), among others. These consequences have been largely studied in parthenogenetic organisms, but studies on fissiparous species are scarce. Differing from parthenogens, fissiparous organisms inherit part of the soma of the progenitor, including somatic mutations. Thus, in the long term, fissiparous reproduction may also result in genetic mosaicism, besides the presence of the Meselson effect and Muller's Ratchet. Dugesiidae planarians show outstanding regeneration capabilities, allowing them to naturally reproduce by fission, either strictly or combined with sex (facultative). Therefore, they are an ideal model to analyze the genetic footprint of fissiparous reproduction, both when it is alternated with sex and when it is the only mode of reproduction. RESULTS In the present study, we generate and analyze intraindividual cloned data of a nuclear and a mitochondrial gene of sexual, fissiparous and facultative wild populations of the species Dugesia subtentaculata. We find that most individuals, independently of their reproductive strategy, are mosaics. However, the intraindividual haplotype and nucleotide diversity of fissiparous and facultative individuals is significantly higher than in sexual individuals, with no signs of Muller's Ratchet. Finally, we also find that this high intraindividual genetic diversity of fissiparous and facultative individuals is composed by different combinations of ancestral and derived haplotypes of the species. CONCLUSIONS The intraindividual analyses of genetic diversity point out that fissiparous reproduction leaves a very special genetic footprint in individuals, characterized by mosaicism combined with the Meselson effect (named in the present study as the mosaic Meselson effect). Interestingly, the different intraindividual combinations of ancestral and derivate genetic diversity indicate that haplotypes generated during periods of fissiparous reproduction can be also transmitted to the progeny through sexual events, resulting in offspring showing a wide range of genetic diversity and putatively allowing purifying selection to act at both intraindividual and individual level. Further investigations, using Dugesia planarians as model organisms, would be of great value to delve into this new model of genetic evolution by the combination of fission and sex.
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Affiliation(s)
- Laia Leria
- Department de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, and Institut de Recerca de la Biodiversitat (IRBio), Barcelona, Catalonia Spain
| | - Miquel Vila-Farré
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Eduard Solà
- Department de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, and Institut de Recerca de la Biodiversitat (IRBio), Barcelona, Catalonia Spain
| | - Marta Riutort
- Department de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, and Institut de Recerca de la Biodiversitat (IRBio), Barcelona, Catalonia Spain
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30
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Parker DJ, Bast J, Jalvingh K, Dumas Z, Robinson-Rechavi M, Schwander T. Repeated Evolution of Asexuality Involves Convergent Gene Expression Changes. Mol Biol Evol 2019; 36:350-364. [PMID: 30445505 PMCID: PMC6404633 DOI: 10.1093/molbev/msy217] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Asexual reproduction has evolved repeatedly from sexual ancestors across a wide range of taxa. Whereas the costs and benefits associated with asexuality have received considerable attention, the molecular changes underpinning the evolution of asexual reproduction remain relatively unexplored. In particular, it is completely unknown whether the repeated evolution of asexual phenotypes involves similar molecular changes, as previous studies have focused on changes occurring in single lineages. Here, we investigate the extent of convergent gene expression changes across five independent transitions to asexuality in stick insects. We compared gene expression of asexual females to females of close sexual relatives in whole-bodies, reproductive tracts, and legs. We identified a striking amount of convergent gene expression change (up to 8% of genes), greatly exceeding that expected by chance. Convergent changes were also tissue-specific, and most likely driven by selection for functional changes. Genes showing convergent changes in the reproductive tract were associated with meiotic spindle formation and centrosome organization. These genes are particularly interesting as they can influence the production of unreduced eggs, a key barrier to asexual reproduction. Changes in legs and whole-bodies were likely involved in female sexual trait decay, with enrichment in terms such as sperm-storage and pigmentation. By identifying changes occurring across multiple independent transitions to asexuality, our results provide a rare insight into the molecular basis of asexual phenotypes and suggest that the evolutionary path to asexuality is highly constrained, requiring repeated changes to the same key genes.
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Affiliation(s)
- Darren J Parker
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Kirsten Jalvingh
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Zoé Dumas
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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31
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Parker DJ, Djordjevic J, Schwander T. Olfactory Proteins in Timema Stick Insects. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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32
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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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33
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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: 7] [Impact Index Per Article: 1.4] [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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34
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Larose C, Parker DJ, Schwander T. Fundamental and realized feeding niche breadths of sexual and asexual stick insects. Proc Biol Sci 2018; 285:20181805. [PMID: 30487310 PMCID: PMC6283937 DOI: 10.1098/rspb.2018.1805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/05/2018] [Indexed: 11/12/2022] Open
Abstract
The factors contributing to the maintenance of sex over asexuality in natural populations remain unclear. Ecological divergences between sexual and asexual lineages could help to maintain reproductive polymorphisms, at least transiently, but the consequences of asexuality for the evolution of ecological niches are unknown. Here, we investigated how niche breadths change in transitions from sexual reproduction to asexuality. We used host plant ranges as a proxy to compare the realized feeding niche breadths of five independently derived asexual Timema stick insect species and their sexual relatives at both the species and population levels. Asexual species had systematically narrower realized niches than sexual species, though this pattern was not apparent at the population level. To investigate how the narrower realized niches of asexual species arise, we performed feeding experiments to estimate fundamental niche breadths but found no systematic differences between reproductive modes. The narrow realized niches found in asexual species are therefore probably a consequence of biotic interactions such as predation or competition, that constrain realized niche size in asexuals more strongly than in sexuals.
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Affiliation(s)
- Chloé Larose
- Department of Ecology and Evolution, University of Lausanne, Quartier Unil-Sorge, CH-1015 Lausanne, Switzerland
| | - Darren J Parker
- Department of Ecology and Evolution, University of Lausanne, Quartier Unil-Sorge, CH-1015 Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Quartier Unil-Sorge, CH-1015 Lausanne, Switzerland
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