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Näsvall K, Boman J, Höök L, Vila R, Wiklund C, Backström N. Nascent evolution of recombination rate differences as a consequence of chromosomal rearrangements. PLoS Genet 2023; 19:e1010717. [PMID: 37549188 PMCID: PMC10434929 DOI: 10.1371/journal.pgen.1010717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 08/17/2023] [Accepted: 07/17/2023] [Indexed: 08/09/2023] Open
Abstract
Reshuffling of genetic variation occurs both by independent assortment of chromosomes and by homologous recombination. Such reshuffling can generate novel allele combinations and break linkage between advantageous and deleterious variants which increases both the potential and the efficacy of natural selection. Here we used high-density linkage maps to characterize global and regional recombination rate variation in two populations of the wood white butterfly (Leptidea sinapis) that differ considerably in their karyotype as a consequence of at least 27 chromosome fissions and fusions. The recombination data were compared to estimates of genetic diversity and measures of selection to assess the relationship between chromosomal rearrangements, crossing over, maintenance of genetic diversity and adaptation. Our data show that the recombination rate is influenced by both chromosome size and number, but that the difference in the number of crossovers between karyotypes is reduced as a consequence of a higher frequency of double crossovers in larger chromosomes. As expected from effects of selection on linked sites, we observed an overall positive association between recombination rate and genetic diversity in both populations. Our results also revealed a significant effect of chromosomal rearrangements on the rate of intergenic diversity change between populations, but limited effects on polymorphisms in coding sequence. We conclude that chromosomal rearrangements can have considerable effects on the recombination landscape and consequently influence both maintenance of genetic diversity and efficiency of selection in natural populations.
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Affiliation(s)
- Karin Näsvall
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, Uppsala, Sweden
| | - Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, Uppsala, Sweden
| | - Lars Höök
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, Uppsala, Sweden
| | - Roger Vila
- Butterfly Diversity and Evolution Lab, Institut de Biologia Evolutiva (CSIC-Univ. Pompeu Fabra), Barcelona, Spain
| | - Christer Wiklund
- Department of Zoology: Division of Ecology, Stockholm University, Stockholm, Sweden
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, Uppsala, Sweden
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2
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Näsvall K, Boman J, Talla V, Backström N. Base Composition, Codon Usage, and Patterns of Gene Sequence Evolution in Butterflies. Genome Biol Evol 2023; 15:evad150. [PMID: 37565492 PMCID: PMC10462419 DOI: 10.1093/gbe/evad150] [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: 11/22/2022] [Revised: 07/17/2023] [Accepted: 08/08/2023] [Indexed: 08/12/2023] Open
Abstract
Coding sequence evolution is influenced by both natural selection and neutral evolutionary forces. In many species, the effects of mutation bias, codon usage, and GC-biased gene conversion (gBGC) on gene sequence evolution have not been detailed. Quantification of how these forces shape substitution patterns is therefore necessary to understand the strength and direction of natural selection. Here, we used comparative genomics to investigate the association between base composition and codon usage bias on gene sequence evolution in butterflies and moths (Lepidoptera), including an in-depth analysis of underlying patterns and processes in one species, Leptidea sinapis. The data revealed significant G/C to A/T substitution bias at third codon position with some variation in the strength among different butterfly lineages. However, the substitution bias was lower than expected from previously estimated mutation rate ratios, partly due to the influence of gBGC. We found that A/T-ending codons were overrepresented in most species, but there was a positive association between the magnitude of codon usage bias and GC-content in third codon positions. In addition, the tRNA-gene population in L. sinapis showed higher GC-content at third codon positions compared to coding sequences in general and less overrepresentation of A/T-ending codons. There was an inverse relationship between synonymous substitutions and codon usage bias indicating selection on synonymous sites. We conclude that the evolutionary rate in Lepidoptera is affected by a complex interaction between underlying G/C -> A/T mutation bias and partly counteracting fixation biases, predominantly conferred by overall purifying selection, gBGC, and selection on codon usage.
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Affiliation(s)
- Karin Näsvall
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Venkat Talla
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
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3
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Nazari V, Lukhtanov VA, Naderi A, Fric ZF, Dincă V, Vila R. More hidden diversity in a cryptic species complex: a new subspecies of Leptideasinapis (Lepidoptera, Pieridae) from Northern Iran. COMPARATIVE CYTOGENETICS 2023; 17:113-128. [PMID: 37304150 PMCID: PMC10252139 DOI: 10.3897/compcytogen.17.102830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/05/2023] [Indexed: 06/13/2023]
Abstract
A new subspecies of Leptideasinapis from Northern Iran, discovered by means of DNA barcoding, is described as Leptideasinapistabarestanassp. nov. The new subspecies is allopatric with respect to other populations of L.sinapis and is genetically distinct, appearing as a well-supported sister clade to all other populations in COI-based phylogenetic reconstructions. Details on karyotype, genitalia, ecology and behaviour for the new subspecies are given and a biogeographical speciation scenario is proposed.
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Affiliation(s)
- Vazrick Nazari
- Department of Biology, University of Padova, Padova, ItalyUniversity of PadovaPadovaItaly
| | - Vladimir A. Lukhtanov
- Department of Karyosystematics, Zoological Institute of Russian Academy of Science, Universitetskaya nab. 1, 199034 St. Petersburg, RussiaZoological Institute of Russian Academy of ScienceSt. PetersburgRussia
| | - Alireza Naderi
- National Natural History Museum & Genetic Resources, Tehran, IranNational Natural History Museum & Genetic ResourcesTehranIran
| | - Zdenek Faltýnek Fric
- Department of Biodiversity and Conservation Biology, Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech RepublicInstitute of Entomology, Biology Centre of the Czech Academy of SciencesČeské BudějoviceCzech Republic
| | - Vlad Dincă
- Ecology and Genetics Research Unit, University of Oulu, Oulu, FinlandUniversity of OuluOuluFinland
- Research Institute of the University of Bucharest (ICUB), University of Bucharest, Bucharest, RomaniaUniversity of BucharestBucharestRomania
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC – Universitat Pompeu Fabra), Barcelona, SpainUniversitat Pompeu FabraBarcelonaSpain
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4
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García-Berro A, Talla V, Vila R, Wai HK, Shipilina D, Chan KG, Pierce NE, Backström N, Talavera G. Migratory behaviour is positively associated with genetic diversity in butterflies. Mol Ecol 2023; 32:560-574. [PMID: 36336800 PMCID: PMC10100375 DOI: 10.1111/mec.16770] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 09/30/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022]
Abstract
Migration is typically associated with risk and uncertainty at the population level, but little is known about its cost-benefit trade-offs at the species level. Migratory insects in particular often exhibit strong demographic fluctuations due to local bottlenecks and outbreaks. Here, we use genomic data to investigate levels of heterozygosity and long-term population size dynamics in migratory insects, as an alternative to classical local and short-term approaches such as regional field monitoring. We analyse whole-genome sequences from 97 Lepidoptera species and show that individuals of migratory species have significantly higher levels of genome-wide heterozygosity, a proxy for effective population size, than do nonmigratory species. Also, we contribute whole-genome data for one of the most emblematic insect migratory species, the painted lady butterfly (Vanessa cardui), sampled across its worldwide distributional range. This species exhibits one of the highest levels of genomic heterozygosity described in Lepidoptera (2.95 ± 0.15%). Coalescent modelling (PSMC) shows historical demographic stability in V. cardui, and high effective population size estimates of 2-20 million individuals 10,000 years ago. The study reveals that the high risks associated with migration and local environmental fluctuations do not seem to decrease overall genetic diversity and demographic stability in migratory Lepidoptera. We propose a "compensatory" demographic model for migratory r-strategist organisms in which local bottlenecks are counterbalanced by reproductive success elsewhere within their typically large distributional ranges. Our findings highlight that the boundaries of populations are substantially different for sedentary and migratory insects, and that, in the latter, local and even regional field monitoring results may not reflect whole population dynamics. Genomic diversity patterns may elucidate key aspects of an insect's migratory nature and population dynamics at large spatiotemporal scales.
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Affiliation(s)
- Aurora García-Berro
- Institut Botànic de Barcelona (IBB), CSIC-Ajuntament de Barcelona, Barcelona, Catalonia, Spain
| | - Venkat Talla
- Department of Ecology and Genetics, Program of Evolutionary Biology, Uppsala University, Uppsala, Sweden
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC-Univ. Pompeu Fabra), Barcelona, Spain
| | - Hong Kar Wai
- Novel Bacteria and Drug Discovery Research Group (NBDD) and Microbiome and Bioresource Research Strength (MBRS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Selangor Darul Ehsan, Malaysia.,Division of Genetics and Molecular Biology, Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Daria Shipilina
- Department of Ecology and Genetics, Program of Evolutionary Biology, Uppsala University, Uppsala, Sweden.,Swedish Collegium for Advanced Study, Uppsala, Sweden
| | - Kok Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia.,International Genome Centre, Jiangsu University, Zhenjiang, China.,Guangdong Provincial Key Laboratory of Marine Biology, Institute of Marine Sciences, Shantou University, Shantou, China
| | - Naomi E Pierce
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
| | - Niclas Backström
- Department of Ecology and Genetics, Program of Evolutionary Biology, Uppsala University, Uppsala, Sweden
| | - Gerard Talavera
- Institut Botànic de Barcelona (IBB), CSIC-Ajuntament de Barcelona, Barcelona, Catalonia, Spain.,Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
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5
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Trait variation in a successful global invader: a large-scale analysis of morphological variance and integration in the brown trout. Biol Invasions 2023. [DOI: 10.1007/s10530-023-03003-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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6
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Moreira LR, Klicka J, Smith BT. Demography and linked selection interact to shape the genomic landscape of codistributed woodpeckers during the Ice Age. Mol Ecol 2023; 32:1739-1759. [PMID: 36617622 DOI: 10.1111/mec.16841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 12/13/2022] [Accepted: 12/20/2022] [Indexed: 01/10/2023]
Abstract
The influence of genetic drift on population dynamics during Pleistocene glacial cycles is well understood, but the role of selection in shaping patterns of genomic variation during these events is less explored. We resequenced whole genomes to investigate how demography and natural selection interact to generate the genomic landscapes of Downy and Hairy Woodpecker, species codistributed in previously glaciated North America. First, we explored the spatial and temporal patterns of genomic diversity produced by neutral evolution. Next, we tested (i) whether levels of nucleotide diversity along the genome are correlated with intrinsic genomic properties, such as recombination rate and gene density, and (ii) whether different demographic trajectories impacted the efficacy of selection. Our results revealed cycles of bottleneck and expansion, and genetic structure associated with glacial refugia. Nucleotide diversity varied widely along the genome, but this variation was highly correlated between the species, suggesting the presence of conserved genomic features. In both taxa, nucleotide diversity was positively correlated with recombination rate and negatively correlated with gene density, suggesting that linked selection played a role in reducing diversity. Despite strong fluctuations in effective population size, the maintenance of relatively large populations during glaciations may have facilitated selection. Under these conditions, we found evidence that the individual demographic trajectory of populations modulated linked selection, with purifying selection being more efficient in removing deleterious alleles in large populations. These results highlight that while genome-wide variation reflects the expected signature of demographic change during climatic perturbations, the interaction of multiple processes produces a predictable and highly heterogeneous genomic landscape.
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Affiliation(s)
- Lucas R Moreira
- Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, USA.,Department of Ornithology, American Museum of Natural History, New York City, New York, USA.,Program in Bioinformatics and Integrative Biology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - John Klicka
- Burke Museum of Natural History and Culture and Department of Biology, University of Washington, Seattle, Washington, USA
| | - Brian Tilston Smith
- Department of Ornithology, American Museum of Natural History, New York City, New York, USA
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7
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Höök L, Näsvall K, Vila R, Wiklund C, Backström N. High-density linkage maps and chromosome level genome assemblies unveil direction and frequency of extensive structural rearrangements in wood white butterflies (Leptidea spp.). Chromosome Res 2023; 31:2. [PMID: 36662301 PMCID: PMC9859909 DOI: 10.1007/s10577-023-09713-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/19/2022] [Accepted: 12/28/2022] [Indexed: 01/21/2023]
Abstract
Karyotypes are generally conserved between closely related species and large chromosome rearrangements typically have negative fitness consequences in heterozygotes, potentially driving speciation. In the order Lepidoptera, most investigated species have the ancestral karyotype and gene synteny is often conserved across deep divergence, although examples of extensive genome reshuffling have recently been demonstrated. The genus Leptidea has an unusual level of chromosome variation and rearranged sex chromosomes, but the extent of restructuring across the rest of the genome is so far unknown. To explore the genomes of the wood white (Leptidea) species complex, we generated eight genome assemblies using a combination of 10X linked reads and HiC data, and improved them using linkage maps for two populations of the common wood white (L. sinapis) with distinct karyotypes. Synteny analysis revealed an extensive amount of rearrangements, both compared to the ancestral karyotype and between the Leptidea species, where only one of the three Z chromosomes was conserved across all comparisons. Most restructuring was explained by fissions and fusions, while translocations appear relatively rare. We further detected several examples of segregating rearrangement polymorphisms supporting a highly dynamic genome evolution in this clade. Fusion breakpoints were enriched for LINEs and LTR elements, which suggests that ectopic recombination might be an important driver in the formation of new chromosomes. Our results show that chromosome count alone may conceal the extent of genome restructuring and we propose that the amount of genome evolution in Lepidoptera might still be underestimated due to lack of taxonomic sampling.
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Affiliation(s)
- L. Höök
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - K. Näsvall
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - R. Vila
- Butterfly Diversity and Evolution Lab, Institut de Biologia Evolutiva (CSIC-UPF), Barcelona, Spain
| | - C. Wiklund
- Department of Zoology, Division of Ecology, Stockholm University, Stockholm, Sweden
| | - N. Backström
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
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8
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Shipilina D, Näsvall K, Höök L, Vila R, Talavera G, Backström N. Linkage mapping and genome annotation give novel insights into gene family expansions and regional recombination rate variation in the painted lady (Vanessa cardui) butterfly. Genomics 2022; 114:110481. [PMID: 36115505 DOI: 10.1016/j.ygeno.2022.110481] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/01/2022] [Accepted: 09/10/2022] [Indexed: 01/14/2023]
Abstract
Characterization of gene family expansions and crossing over is crucial for understanding how organisms adapt to the environment. Here, we develop a high-density linkage map and detailed genome annotation of the painted lady butterfly (Vanessa cardui) - a non-diapausing, highly polyphagous species famous for its long-distance migratory behavior and almost cosmopolitan distribution. Our results reveal a complex interplay between regional recombination rate variation, gene duplications and transposable element activity shaping the genome structure of the painted lady. We identify several lineage specific gene family expansions. Their functions are mainly associated with protein and fat metabolism, detoxification, and defense against infection - critical processes for the painted lady's unique life-history. Furthermore, the detailed recombination maps allow us to characterize the regional recombination landscape, data that reveal a strong effect of chromosome size on the recombination rate, a limited impact of GC-biased gene conversion and a positive association between recombination and short interspersed elements.
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Affiliation(s)
- Daria Shipilina
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden; Swedish Collegium for Advanced Study, Thunbergsvägen 2, 75236 Uppsala, Sweden.
| | - Karin Näsvall
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
| | - Lars Höök
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
| | - Roger Vila
- The Butterfly Diversity and Evolution Lab, Institut de Biologia Evolutiva, Passeig Martim de la Barceloneta 37-49, 08003 Barcelona, Spain
| | - Gerard Talavera
- Institut Botànic de Barcelona (IBB), CSIC-Ajuntament de Barcelona, Passeig del Migdia s/n, 08038 Barcelona, Spain
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
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9
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Santos SHD, Peery RM, Miller JM, Dao A, Lyu FH, Li X, Li MH, Coltman DW. Ancient hybridization patterns between bighorn and thinhorn sheep. Mol Ecol 2021; 30:6273-6288. [PMID: 34845798 DOI: 10.1111/mec.16136] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 07/27/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022]
Abstract
Whole-genome sequencing has advanced the study of species evolution, including the detection of genealogical discordant events such as ancient hybridization and incomplete lineage sorting (ILS). The evolutionary history of bighorn (Ovis canadensis) and thinhorn (Ovis dalli) sheep present an ideal system to investigate evolutionary discordance due to their recent and rapid radiation and putative secondary contact between bighorn and thinhorn sheep subspecies, specifically the dark pelage Stone sheep (O. dalli stonei) and predominately white Dall sheep (O. dalli dalli), during the last ice age. Here, we used multiple genomes of bighorn and thinhorn sheep, together with snow (O. nivicola) and the domestic sheep (O. aries) as outgroups, to assess their phylogenomic history, potential introgression patterns and their adaptive consequences. Among the Pachyceriforms (snow, bighorn and thinhorn sheep) a consistent monophyletic species tree was retrieved; however, many genealogical discordance patterns were observed. Alternative phylogenies frequently placed Stone and bighorn as sister clades. This relationship occurred more often and was less divergent than that between Dall and bighorn. We also observed many blocks containing introgression signal between Stone and bighorn genomes in which coat colour genes were present. Introgression signals observed between Dall and bighorn were more random and less frequent, and therefore probably due to ILS or intermediary secondary contact. These results strongly suggest that Stone sheep originated from a complex series of events, characterized by multiple, ancient periods of secondary contact with bighorn sheep.
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Affiliation(s)
- Sarah H D Santos
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Rhiannon M Peery
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Joshua M Miller
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Anh Dao
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Feng-Hua Lyu
- College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Xin Li
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Chinese Academy of Sciences (CAS), Beijing, China.,University of Chinese Academy of Sciences (UCAS), Beijing, China
| | - Meng-Hua Li
- CAS Key Laboratory of Animal Ecology and Conservation Biology, Chinese Academy of Sciences (CAS), Beijing, China
| | - David W Coltman
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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10
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Boman J, Mugal CF, Backström N. The Effects of GC-Biased Gene Conversion on Patterns of Genetic Diversity among and across Butterfly Genomes. Genome Biol Evol 2021; 13:evab064. [PMID: 33760095 PMCID: PMC8175052 DOI: 10.1093/gbe/evab064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2021] [Indexed: 12/28/2022] Open
Abstract
Recombination reshuffles the alleles of a population through crossover and gene conversion. These mechanisms have considerable consequences on the evolution and maintenance of genetic diversity. Crossover, for example, can increase genetic diversity by breaking the linkage between selected and nearby neutral variants. Bias in favor of G or C alleles during gene conversion may instead promote the fixation of one allele over the other, thus decreasing diversity. Mutation bias from G or C to A and T opposes GC-biased gene conversion (gBGC). Less recognized is that these two processes may-when balanced-promote genetic diversity. Here, we investigate how gBGC and mutation bias shape genetic diversity patterns in wood white butterflies (Leptidea sp.). This constitutes the first in-depth investigation of gBGC in butterflies. Using 60 resequenced genomes from six populations of three species, we find substantial variation in the strength of gBGC across lineages. When modeling the balance of gBGC and mutation bias and comparing analytical results with empirical data, we reject gBGC as the main determinant of genetic diversity in these butterfly species. As alternatives, we consider linked selection and GC content. We find evidence that high values of both reduce diversity. We also show that the joint effects of gBGC and mutation bias can give rise to a diversity pattern which resembles the signature of linked selection. Consequently, gBGC should be considered when interpreting the effects of linked selection on levels of genetic diversity.
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Affiliation(s)
- Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
| | - Carina F Mugal
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
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11
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Kaňuch P, Berggren Å, Cassel-Lundhagen A. A clue to invasion success: genetic diversity quickly rebounds after introduction bottlenecks. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02426-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractOne of the fundamental questions in invasion biology is to understand the genetic mechanisms behind success or failure during the establishment of a species. However, major limitations to understanding are usually a lack of spatiotemporal population data and information on the populations’ colonisation history. In a large-scale, detailed study on the bush-cricket Metrioptera roeselii 70 groups of founders were introduced in areas outside the species’ distribution range. We examined how (1) the number of founders (2–32 individuals), (2) the time since establishment (7 or 15 years after introduction) and (3) possible gene flow affected establishment success and temporal genetic changes of the introduced populations. We found higher establishment success in introductions with larger propagule sizes but genetic diversity indices were only partly correlated to propagule size. As expected, introduced populations were more similar to their founder population the larger the propagule size was. However, even if apparent at first, most of the differentiation in the small propagule introductions disappeared over time. Surprisingly, genetic variability was regained to a level comparable to the large and outbreeding founder population only 15 generations after severe demographic bottlenecks. We suggest that the establishment of these populations could be a result of several mechanisms acting in synergy. Here, rapid increase in genetic diversity of few introductions could potentially be attributed to limited gene flow from adjacent populations, behavioural adaptations and/or even increased mutation rate. We present unique insights into genetic processes that point towards traits that are important for understanding species’ invasiveness.
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12
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Yoshido A, Šíchová J, Pospíšilová K, Nguyen P, Voleníková A, Šafář J, Provazník J, Vila R, Marec F. Evolution of multiple sex-chromosomes associated with dynamic genome reshuffling in Leptidea wood-white butterflies. Heredity (Edinb) 2020; 125:138-154. [PMID: 32518391 PMCID: PMC7426936 DOI: 10.1038/s41437-020-0325-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/21/2020] [Accepted: 05/21/2020] [Indexed: 12/13/2022] Open
Abstract
Sex-chromosome systems tend to be highly conserved and knowledge about their evolution typically comes from macroevolutionary inference. Rapidly evolving complex sex-chromosome systems represent a rare opportunity to study the mechanisms of sex-chromosome evolution at unprecedented resolution. Three cryptic species of wood-white butterflies—Leptidea juvernica, L. sinapis and L. reali—have each a unique set of multiple sex-chromosomes with 3–4 W and 3–4 Z chromosomes. Using a transcriptome-based microarray for comparative genomic hybridisation (CGH) and a library of bacterial artificial chromosome (BAC) clones, both developed in L. juvernica, we identified Z-linked Leptidea orthologs of Bombyx mori genes and mapped them by fluorescence in situ hybridisation (FISH) with BAC probes on multiple Z chromosomes. In all three species, we determined synteny blocks of autosomal origin and reconstructed the evolution of multiple sex-chromosomes. In addition, we identified W homologues of Z-linked orthologs and characterised their molecular differentiation. Our results suggest that the multiple sex-chromosome system evolved in a common ancestor as a result of dynamic genome reshuffling through repeated rearrangements between the sex chromosomes and autosomes, including translocations, fusions and fissions. Thus, the initial formation of neo-sex chromosomes could not have played a role in reproductive isolation between these Leptidea species. However, the subsequent species-specific fissions of several neo-sex chromosomes could have contributed to their reproductive isolation. Then, significantly increased numbers of Z-linked genes and independent neo-W chromosome degeneration could accelerate the accumulation of genetic incompatibilities between populations and promote their divergence resulting in speciation.
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Affiliation(s)
- Atsuo Yoshido
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Jindra Šíchová
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Kristýna Pospíšilová
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Petr Nguyen
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Anna Voleníková
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic.,Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Jan Šafář
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Hana for Biotechnological and Agricultural Research, Šlechtitelů 31, 779 00, Olomouc, Czech Republic
| | - Jan Provazník
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic.,Genomics Core Facility, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC-UPF), Pg. Marítim de la Barceloneta 37, 08003, Barcelona, Spain
| | - František Marec
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05, České Budějovice, Czech Republic.
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