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Mirarab S, Rivas-González I, Feng S, Stiller J, Fang Q, Mai U, Hickey G, Chen G, Brajuka N, Fedrigo O, Formenti G, Wolf JBW, Howe K, Antunes A, Schierup MH, Paten B, Jarvis ED, Zhang G, Braun EL. A region of suppressed recombination misleads neoavian phylogenomics. Proc Natl Acad Sci U S A 2024; 121:e2319506121. [PMID: 38557186 PMCID: PMC11009670 DOI: 10.1073/pnas.2319506121] [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: 11/14/2023] [Accepted: 02/07/2024] [Indexed: 04/04/2024] Open
Abstract
Genomes are typically mosaics of regions with different evolutionary histories. When speciation events are closely spaced in time, recombination makes the regions sharing the same history small, and the evolutionary history changes rapidly as we move along the genome. When examining rapid radiations such as the early diversification of Neoaves 66 Mya, typically no consistent history is observed across segments exceeding kilobases of the genome. Here, we report an exception. We found that a 21-Mb region in avian genomes, mapped to chicken chromosome 4, shows an extremely strong and discordance-free signal for a history different from that of the inferred species tree. Such a strong discordance-free signal, indicative of suppressed recombination across many millions of base pairs, is not observed elsewhere in the genome for any deep avian relationships. Although long regions with suppressed recombination have been documented in recently diverged species, our results pertain to relationships dating circa 65 Mya. We provide evidence that this strong signal may be due to an ancient rearrangement that blocked recombination and remained polymorphic for several million years prior to fixation. We show that the presence of this region has misled previous phylogenomic efforts with lower taxon sampling, showing the interplay between taxon and locus sampling. We predict that similar ancient rearrangements may confound phylogenetic analyses in other clades, pointing to a need for new analytical models that incorporate the possibility of such events.
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Affiliation(s)
- Siavash Mirarab
- Electrical and Computer Engineering Department, University of California, San Diego, CA95032
| | | | - Shaohong Feng
- Center for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou310058, China
- Liangzhu Laboratory, Zhejiang University, Hangzhou311121, China
| | - Josefin Stiller
- Section for Ecology & Evolution, Department of Biology, University of Copenhagen, København2100, Denmark
| | - Qi Fang
- BGI-Research, Shenzhen518083, China
| | - Uyen Mai
- Electrical and Computer Engineering Department, University of California, San Diego, CA95032
| | - Glenn Hickey
- Genomics Institute, University of California, Santa Cruz, CA96064
| | - Guangji Chen
- Center for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou310058, China
- Liangzhu Laboratory, Zhejiang University, Hangzhou311121, China
| | - Nadolina Brajuka
- Vertebrate Genome Lab, Rockefeller University, New York, NY10065
| | - Olivier Fedrigo
- Vertebrate Genome Lab, Rockefeller University, New York, NY10065
| | - Giulio Formenti
- Vertebrate Genome Lab, Rockefeller University, New York, NY10065
| | - Jochen B. W. Wolf
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximillians-Universität, Munich82152, Germany
| | - Kerstin Howe
- Tree of Life Division, Wellcome Sanger Institute, CambridgeCB10 1RQ, United Kingdom
| | - Agostinho Antunes
- Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto4099-002, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Porto4099-002, Portugal
| | | | - Benedict Paten
- Genomics Institute, University of California, Santa Cruz, CA96064
| | - Erich D. Jarvis
- Vertebrate Genome Lab, Rockefeller University, New York, NY10065
| | - Guojie Zhang
- Center for Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou310058, China
| | - Edward L. Braun
- Department of Biology, University of Florida, Gainesville, FL32611
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2
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Chase MA, Vilcot M, Mugal CF. The role of recombination dynamics in shaping signatures of direct and indirect selection across the Ficedula flycatcher genome †. Proc Biol Sci 2024; 291:20232382. [PMID: 38228173 DOI: 10.1098/rspb.2023.2382] [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: 10/20/2022] [Accepted: 12/14/2023] [Indexed: 01/18/2024] Open
Abstract
Recombination is a central evolutionary process that reshuffles combinations of alleles along chromosomes, and consequently is expected to influence the efficacy of direct selection via Hill-Robertson interference. Additionally, the indirect effects of selection on neutral genetic diversity are expected to show a negative relationship with recombination rate, as background selection and genetic hitchhiking are stronger when recombination rate is low. However, owing to the limited availability of recombination rate estimates across divergent species, the impact of evolutionary changes in recombination rate on genomic signatures of selection remains largely unexplored. To address this question, we estimate recombination rate in two Ficedula flycatcher species, the taiga flycatcher (Ficedula albicilla) and collared flycatcher (Ficedula albicollis). We show that recombination rate is strongly correlated with signatures of indirect selection, and that evolutionary changes in recombination rate between species have observable impacts on this relationship. Conversely, signatures of direct selection on coding sequences show little to no relationship with recombination rate, even when restricted to genes where recombination rate is conserved between species. Thus, using measures of indirect and direct selection that bridge micro- and macro-evolutionary timescales, we demonstrate that the role of recombination rate and its dynamics varies for different signatures of selection.
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Affiliation(s)
- Madeline A Chase
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- Swiss Ornithological Institute, 6204 Sempach, Switzerland
| | - Maurine Vilcot
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- CEFE, University of Montpellier, CNRS, EPHE, IRD, 34293 Montpellier 5, France
| | - Carina F Mugal
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- Laboratory of Biometry and Evolutionary Biology, University of Lyon 1, CNRS UMR 5558, 69622 Villeurbanne cedex, France
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3
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Scarparo G, Palanchon M, Brelsford A, Purcell J. Social antagonism facilitates supergene expansion in ants. Curr Biol 2023; 33:5085-5095.e4. [PMID: 37979579 DOI: 10.1016/j.cub.2023.10.049] [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: 04/26/2023] [Revised: 08/07/2023] [Accepted: 10/25/2023] [Indexed: 11/20/2023]
Abstract
Antagonistic selection has long been considered a major driver of the formation and expansion of sex chromosomes. For example, sexually antagonistic variation on an autosome can select for suppressed recombination between that autosome and the sex chromosome, leading to a neo-sex chromosome. Autosomal supergenes, chromosomal regions containing tightly linked variants affecting the same complex trait, share similarities with sex chromosomes, raising the possibility that sex chromosome evolution models can explain the evolution of genome structure and recombination in other contexts. We tested this premise in a Formica ant species, wherein we identified four supergene haplotypes on chromosome 3 underlying colony social organization and sex ratio. We discovered a novel rearranged supergene variant (9r) on chromosome 9 underlying queen miniaturization. The 9r is in strong linkage disequilibrium with one chromosome 3 haplotype (P2) found in multi-queen (polygyne) colonies. We suggest that queen miniaturization is strongly disfavored in the single-queen (monogyne) background and is thus socially antagonistic. As such, divergent selection experienced by ants living in alternative social "environments" (monogyne and polygyne) may have contributed to the emergence of a genetic polymorphism on chromosome 9 and associated queen-size dimorphism. Consequently, an ancestral polygyne-associated haplotype may have expanded to include the polymorphism on chromosome 9, resulting in a larger region of suppressed recombination spanning two chromosomes. This process is analogous to the formation of neo-sex chromosomes and consistent with models of expanding regions of suppressed recombination. We propose that miniaturized queens, 16%-20% smaller than queens without 9r, could be incipient intraspecific social parasites.
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Affiliation(s)
- Giulia Scarparo
- Department of Entomology, University of California, Riverside, 165 Entomology Bldg. Citrus Drive, Riverside, CA 92521, USA.
| | - Marie Palanchon
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 2710 Life Science Bldg., Riverside, CA 92521, USA
| | - Alan Brelsford
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 2710 Life Science Bldg., Riverside, CA 92521, USA
| | - Jessica Purcell
- Department of Entomology, University of California, Riverside, 165 Entomology Bldg. Citrus Drive, Riverside, CA 92521, USA.
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4
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Zhang H, Hansson B. RecView: an interactive R application for locating recombination positions using pedigree data. BMC Genomics 2023; 24:712. [PMID: 38007417 PMCID: PMC10676570 DOI: 10.1186/s12864-023-09807-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND Recombination reshuffles alleles at linked loci, allowing genes to evolve independently and consequently enhancing the efficiency of selection. This makes quantifying recombination along chromosomes an important goal for understanding how selection and drift are acting on genes and chromosomes. RESULTS We present RecView, an interactive R application and its homonymous R package, to facilitate locating recombination positions along chromosomes or scaffolds using whole-genome genotype data of a three-generation pedigree. RecView analyses and plots the grandparent-of-origin of all informative alleles along each chromosome of the offspring in the pedigree, and infers recombination positions with either of two built-in algorithms: one based on change in the proportion of the alleles with specific grandparent-of-origin, and one on the degree of continuity of alleles with the same grandparent-of-origin. RecView handles multiple offspring and chromosomes simultaneously, and all putative recombination positions are reported in base pairs together with an estimated precision based on the local density of informative alleles. We demonstrate RecView using genotype data of a passerine bird with an available reference genome, the great reed warbler (Acrocephalus arundinaceus), and show that recombination events can be located to specific positions. CONCLUSIONS RecView is an easy-to-use and highly effective application for locating recombination positions with high precision. RecView is available on GitHub ( https://github.com/HKyleZhang/RecView.git ).
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Affiliation(s)
- Hongkai Zhang
- Department of Biology, Lund University, Lund, 22362, Sweden.
| | - Bengt Hansson
- Department of Biology, Lund University, Lund, 22362, Sweden.
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Zhang H, Lundberg M, Tarka M, Hasselquist D, Hansson B. Evidence of Site-Specific and Male-Biased Germline Mutation Rate in a Wild Songbird. Genome Biol Evol 2023; 15:evad180. [PMID: 37793164 PMCID: PMC10627410 DOI: 10.1093/gbe/evad180] [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: 06/09/2023] [Revised: 09/07/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023] Open
Abstract
Germline mutations are the ultimate source of genetic variation and the raw material for organismal evolution. Despite their significance, the frequency and genomic locations of mutations, as well as potential sex bias, are yet to be widely investigated in most species. To address these gaps, we conducted whole-genome sequencing of 12 great reed warblers (Acrocephalus arundinaceus) in a pedigree spanning 3 generations to identify single-nucleotide de novo mutations (DNMs) and estimate the germline mutation rate. We detected 82 DNMs within the pedigree, primarily enriched at CpG sites but otherwise randomly located along the chromosomes. Furthermore, we observed a pronounced sex bias in DNM occurrence, with male warblers exhibiting three times more mutations than females. After correction for false negatives and adjusting for callable sites, we obtained a mutation rate of 7.16 × 10-9 mutations per site per generation (m/s/g) for the autosomes and 5.10 × 10-9 m/s/g for the Z chromosome. To demonstrate the utility of species-specific mutation rates, we applied our autosomal mutation rate in models reconstructing the demographic history of the great reed warbler. We uncovered signs of drastic population size reductions predating the last glacial period (LGP) and reduced gene flow between western and eastern populations during the LGP. In conclusion, our results provide one of the few direct estimates of the mutation rate in wild songbirds and evidence for male-driven mutations in accordance with theoretical expectations.
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Affiliation(s)
- Hongkai Zhang
- Department of Biology, Lund University, Lund, Sweden
| | - Max Lundberg
- Department of Biology, Lund University, Lund, Sweden
| | - Maja Tarka
- Department of Biology, Lund University, Lund, Sweden
| | | | - Bengt Hansson
- Department of Biology, Lund University, Lund, Sweden
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6
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Rasoarahona R, Wattanadilokchatkun P, Panthum T, Jaisamut K, Lisachov A, Thong T, Singchat W, Ahmad SF, Han K, Kraichak E, Muangmai N, Koga A, Duengkae P, Antunes A, Srikulnath K. MicrosatNavigator: exploring nonrandom distribution and lineage-specificity of microsatellite repeat motifs on vertebrate sex chromosomes across 186 whole genomes. Chromosome Res 2023; 31:29. [PMID: 37775555 DOI: 10.1007/s10577-023-09738-4] [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: 04/18/2023] [Revised: 08/11/2023] [Accepted: 09/05/2023] [Indexed: 10/01/2023]
Abstract
Microsatellites are short tandem DNA repeats, ubiquitous in genomes. They are believed to be under selection pressure, considering their high distribution and abundance beyond chance or random accumulation. However, limited analysis of microsatellites in single taxonomic groups makes it challenging to understand their evolutionary significance across taxonomic boundaries. Despite abundant genomic information, microsatellites have been studied in limited contexts and within a few species, warranting an unbiased examination of their genome-wide distribution in distinct versus closely related-clades. Large-scale comparisons have revealed relevant trends, especially in vertebrates. Here, "MicrosatNavigator", a new tool that allows quick and reliable investigation of perfect microsatellites in DNA sequences, was developed. This tool can identify microsatellites across the entire genome sequences. Using this tool, microsatellite repeat motifs were identified in the genome sequences of 186 vertebrates. A significant positive correlation was noted between the abundance, density, length, and GC bias of microsatellites and specific lineages. The (AC)n motif is the most prevalent in vertebrate genomes, showing distinct patterns in closely related species. Longer microsatellites were observed on sex chromosomes in birds and mammals but not on autosomes. Microsatellites on sex chromosomes of non-fish vertebrates have the lowest GC content, whereas high-GC microsatellites (≥ 50 M% GC) are preferred in bony and cartilaginous fishes. Thus, similar selective forces and mutational processes may constrain GC-rich microsatellites to different clades. These findings should facilitate investigations into the roles of microsatellites in sex chromosome differentiation and provide candidate microsatellites for functional analysis across the vertebrate evolutionary spectrum.
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Affiliation(s)
- Ryan Rasoarahona
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Sciences for Industry, Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Pish Wattanadilokchatkun
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Thitipong Panthum
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Kitipong Jaisamut
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Artem Lisachov
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Thanyapat Thong
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Worapong Singchat
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Syed Farhan Ahmad
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Kyudong Han
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Department of Microbiology, College of Science & Technology, Dankook University, Cheonan, 31116, Republic of Korea
- Center for Bio-Medical Engineering Core Facility, Dankook University, Cheonan, 31116, Republic of Korea
| | - Ekaphan Kraichak
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Department of Botany, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Narongrit Muangmai
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Department of Fishery Biology, Faculty of Fisheries, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Akihiko Koga
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Prateep Duengkae
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand
| | - Agostinho Antunes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros Do Porto de Leixes, Av. General Norton de Matos, S/N, 4450-208, Porto, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, S/N, 4169-007, Porto, Portugal
| | - Kornsorn Srikulnath
- Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand.
- Sciences for Industry, Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand.
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, 10900, Thailand.
- Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Kasetsart University, (CASTNAR, NRU-KU, Thailand), Bangkok, 10900, Thailand.
- Center of Excellence on Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok, 10900, Thailand.
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7
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Mellinger S, Stervander M, Lundberg M, Drews A, Westerdahl H. Improved haplotype resolution of highly duplicated MHC genes in a long-read genome assembly using MiSeq amplicons. PeerJ 2023; 11:e15480. [PMID: 37456901 PMCID: PMC10349553 DOI: 10.7717/peerj.15480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/08/2023] [Indexed: 07/18/2023] Open
Abstract
Long-read sequencing offers a great improvement in the assembly of complex genomic regions, such as the major histocompatibility complex (MHC) region, which can contain both tandemly duplicated MHC genes (paralogs) and high repeat content. The MHC genes have expanded in passerine birds, resulting in numerous MHC paralogs, with relatively high sequence similarity, making the assembly of the MHC region challenging even with long-read sequencing. In addition, MHC genes show rather high sequence divergence between alleles, making diploid-aware assemblers incorrectly classify haplotypes from the same locus as sequences originating from different genomic regions. Consequently, the number of MHC paralogs can easily be over- or underestimated in long-read assemblies. We therefore set out to verify the MHC diversity in an original and a haplotype-purged long-read assembly of one great reed warbler Acrocephalus arundinaceus individual (the focal individual) by using Illumina MiSeq amplicon sequencing. Single exons, representing MHC class I (MHC-I) and class IIB (MHC-IIB) alleles, were sequenced in the focal individual and mapped to the annotated MHC alleles in the original long-read genome assembly. Eighty-four percent of the annotated MHC-I alleles in the original long-read genome assembly were detected using 55% of the amplicon alleles and likewise, 78% of the annotated MHC-IIB alleles were detected using 61% of the amplicon alleles, indicating an incomplete annotation of MHC genes. In the haploid genome assembly, each MHC-IIB gene should be represented by one allele. The parental origin of the MHC-IIB amplicon alleles in the focal individual was determined by sequencing MHC-IIB in its parents. Two of five larger scaffolds, containing 6-19 MHC-IIB paralogs, had a maternal and paternal origin, respectively, as well as a high nucleotide similarity, which suggests that these scaffolds had been incorrectly assigned as belonging to different loci in the genome rather than as alternate haplotypes of the same locus. Therefore, the number of MHC-IIB paralogs was overestimated in the haploid genome assembly. Based on our findings we propose amplicon sequencing as a suitable complement to long-read sequencing for independent validation of the number of paralogs in general and for haplotype inference in multigene families in particular.
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Affiliation(s)
- Samantha Mellinger
- Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden
| | - Martin Stervander
- Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden
- Department of Biology and Environmental Science, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
- Bird Group, Natural History Museum, Tring, Hertfordshire, United Kingdom
| | - Max Lundberg
- Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden
| | - Anna Drews
- Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden
| | - Helena Westerdahl
- Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Lund, Sweden
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8
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Burley JT, Orzechowski SCM, Sin SYW, Edwards SV. Whole-genome phylogeography of the blue-faced honeyeater (Entomyzon cyanotis) and discovery and characterization of a neo-Z chromosome. Mol Ecol 2023; 32:1248-1270. [PMID: 35797346 DOI: 10.1111/mec.16604] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 06/22/2022] [Accepted: 07/04/2022] [Indexed: 11/28/2022]
Abstract
Whole-genome surveys of genetic diversity and geographic variation often yield unexpected discoveries of novel structural variation, which long-read DNA sequencing can help clarify. Here, we report on whole-genome phylogeography of a bird exhibiting classic vicariant geographies across Australia and New Guinea, the blue-faced honeyeater (Entomyzon cyanotis), and the discovery and characterization of a novel neo-Z chromosome by long-read sequencing. Using short-read genome-wide SNPs, we inferred population divergence events within E. cyanotis across the Carpentarian and other biogeographic barriers during the Pleistocene (~0.3-1.7 Ma). Evidence for introgression between nonsister populations supports a hypothesis of reticulate evolution around a triad of dynamic barriers around Pleistocene Lake Carpentaria between Australia and New Guinea. During this phylogeographic survey, we discovered a large (134 Mbp) neo-Z chromosome and we explored its diversity, divergence and introgression landscape. We show that, as in some sylvioid passerine birds, a fusion occurred between chromosome 5 and the Z chromosome to form a neo-Z chromosome; and in E. cyanotis, the ancestral pseudoautosomal region (PAR) appears nonrecombinant between Z and W, along with most of the fused chromosome 5. The added recombination-suppressed portion of the neo-Z (~37.2 Mbp) displays reduced diversity and faster population genetic differentiation compared with the ancestral-Z. Yet, the new PAR (~17.4 Mbp) shows elevated diversity and reduced differentiation compared to autosomes, potentially resulting from introgression. In our case, long-read sequencing helped clarify the genomic landscape of population divergence on autosomes and sex chromosomes in a species where prior knowledge of genome structure was still incomplete.
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Affiliation(s)
- John T Burley
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA.,Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, Uppsala, Sweden.,Department of Ecology Evolution and Organismal Biology, Brown University, Providence, Rhode Island, USA.,Institute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USA
| | | | - Simon Yung Wa Sin
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA.,School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Scott V Edwards
- Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA
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9
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Lundberg M, Mackintosh A, Petri A, Bensch S. Inversions maintain differences between migratory phenotypes of a songbird. Nat Commun 2023; 14:452. [PMID: 36707538 PMCID: PMC9883250 DOI: 10.1038/s41467-023-36167-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 01/18/2023] [Indexed: 01/28/2023] Open
Abstract
Structural rearrangements have been shown to be important in local adaptation and speciation, but have been difficult to reliably identify and characterize in non-model species. Here we combine long reads, linked reads and optical mapping to characterize three divergent chromosome regions in the willow warbler Phylloscopus trochilus, of which two are associated with differences in migration and one with an environmental gradient. We show that there are inversions (0.4-13 Mb) in each of the regions and that the divergence times between inverted and non-inverted haplotypes are similar across the regions (~1.2 Myrs), which is compatible with a scenario where inversions arose in either of two allopatric populations that subsequently hybridized. The improved genomes allow us to detect additional functional differences in the divergent regions, providing candidate genes for migration and adaptations to environmental gradients.
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Affiliation(s)
- Max Lundberg
- Department of Biology, Lund University, Lund, Sweden.
| | | | - Anna Petri
- Science for Life Laboratory, Uppsala Genome Center, Uppsala University, Uppsala, Sweden
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10
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Sigeman H, Zhang H, Ali Abed S, Hansson B. A novel neo-sex chromosome in Sylvietta brachyura (Macrosphenidae) adds to the extraordinary avian sex chromosome diversity among Sylvioidea songbirds. J Evol Biol 2022; 35:1797-1805. [PMID: 36156325 PMCID: PMC10087220 DOI: 10.1111/jeb.14096] [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: 01/26/2022] [Revised: 06/03/2022] [Accepted: 07/21/2022] [Indexed: 11/29/2022]
Abstract
We report the discovery of a novel neo-sex chromosome in an African warbler, Sylvietta brachyura (northern crombec; Macrosphenidae). This species is part of the Sylvioidea superfamily, where four separate autosome-sex chromosome translocation events have previously been discovered via comparative genomics of 11 of the 22 families in this clade. Our discovery here resulted from analyses of genomic data of single species-representatives from three additional Sylvioidea families (Macrosphenidae, Pycnonotidae and Leiothrichidae). In all three species, we confirmed the translocation of a part of chromosome 4A to the sex chromosomes, which originated basally in Sylvioidea. In S. brachyura, we found that a part of chromosome 8 has been translocated to the sex chromosomes, forming a unique neo-sex chromosome in this lineage. Furthermore, the non-recombining part of 4A in S. brachyura is smaller than in other Sylvioidea species, which suggests that recombination continued along this region after the fusion event in the Sylvioidea ancestor. These findings reveal additional sex chromosome diversity among the Sylvioidea, where five separate translocation events are now confirmed.
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Affiliation(s)
- Hanna Sigeman
- Department of Biology, Lund University, Lund, Sweden.,Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Hongkai Zhang
- Department of Biology, Lund University, Lund, Sweden
| | | | - Bengt Hansson
- Department of Biology, Lund University, Lund, Sweden
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11
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Elkrewi M, Khauratovich U, Toups MA, Bett VK, Mrnjavac A, Macon A, Fraisse C, Sax L, Huylmans AK, Hontoria F, Vicoso B. ZW sex-chromosome evolution and contagious parthenogenesis in Artemia brine shrimp. Genetics 2022; 222:6670797. [PMID: 35977389 PMCID: PMC9526061 DOI: 10.1093/genetics/iyac123] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Eurasian brine shrimp (genus Artemia) have closely related sexual and asexual lineages of parthenogenetic females, which produce rare males at low frequencies. Although they are known to have ZW chromosomes, these are not well characterized, and it is unclear whether they are shared across the clade. Furthermore, the underlying genetic architecture of the transmission of asexuality, which can occur when rare males mate with closely related sexual females, is not well understood. We produced a chromosome-level assembly for the sexual Eurasian species A. sinica and characterized in detail the pair of sex chromosomes of this species. We combined this new assembly with short-read genomic data for the sexual species A. sp. Kazakhstan and several asexual lineages of A. parthenogenetica, allowing us to perform an in-depth characterization of sex-chromosome evolution across the genus. We identified a small differentiated region of the ZW pair that is shared by all sexual and asexual lineages, supporting the shared ancestry of the sex chromosomes. We also inferred that recombination suppression has spread to larger sections of the chromosome independently in the American and Eurasian lineages. Finally, we took advantage of a rare male, which we backcrossed to sexual females, to explore the genetic basis of asexuality. Our results suggest that parthenogenesis is likely partly controlled by a locus on the Z chromosome, highlighting the interplay between sex determination and asexuality.
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Affiliation(s)
- Marwan Elkrewi
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria
| | - Uladzislava Khauratovich
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.,Department of Chromosome Biology, Max Perutz Labs, University of Vienna, 1030, Austria
| | - Melissa A Toups
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.,Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, BH12 5BB, UK
| | | | - Andrea Mrnjavac
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria
| | - Ariana Macon
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria
| | - Christelle Fraisse
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.,CNRS, Univ. Lille, UMR 8198-Evo-Eco-Paleo, F-59000 Lille, France
| | - Luca Sax
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.,Lewis and Clark College, Portland, OR 97219, USA
| | - Ann Kathrin Huylmans
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria.,Institute of Organismic and Molecular Evolution, Johannes Guttenberg Universität Mainz, Mainz, 55122, Germany
| | - Francisco Hontoria
- Instituto de Acuicultura de Torre de la Sal (IATS-CSIC), Ribera de Cabanes, 12595, Spain
| | - Beatriz Vicoso
- Institute of Science and Technology Austria, Klosterneuburg, 3400, Austria
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12
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Zhang H, Sigeman H, Hansson B. Assessment of phylogenetic approaches to study the timing of recombination cessation on sex chromosomes. J Evol Biol 2022; 35:1721-1733. [PMID: 35895083 PMCID: PMC10086819 DOI: 10.1111/jeb.14068] [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: 01/28/2022] [Revised: 06/18/2022] [Accepted: 06/26/2022] [Indexed: 12/01/2022]
Abstract
The evolution of sex chromosomes is hypothesized to be punctuated by consecutive recombination cessation events, forming "evolutionary strata" that ceased to recombine at different time points. The demarcation of evolutionary strata is often assessed by estimates of the timing of recombination cessation (tRC ) along the sex chromosomes, commonly inferred from the level of synonymous divergence or with species phylogenies at gametologous (X-Y or Z-W) sequence data. However, drift and selection affect sequences unpredictably and introduce uncertainty when inferring tRC . Here, we assess two alternative phylogenetic approaches to estimate tRC ; (i) the expected likelihood weight (ELW) approach that finds the most likely topology among a set of hypothetical topologies and (ii) the BEAST approach that estimates tRC with specified calibration priors on a reference species topology. By using Z and W gametologs of an old and a young evolutionary stratum on the neo-sex chromosome of Sylvioidea songbirds, we show that the ELW and BEAST approaches yield similar tRC estimates, and that both outperform two frequently applied approaches utilizing synonymous substitution rates (dS) and maximum likelihood (ML) trees, respectively. Moreover, we demonstrate that both ELW and BEAST provide more precise tRC estimates when sequences of multiple species are included in the analyses.
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Affiliation(s)
- Hongkai Zhang
- Department of Biology, Lund University, Lund, Sweden
| | - Hanna Sigeman
- Department of Biology, Lund University, Lund, Sweden
| | - Bengt Hansson
- Department of Biology, Lund University, Lund, Sweden
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13
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Ponnikas S, Sigeman H, Lundberg M, Hansson B. Extreme variation in recombination rate and genetic diversity along the Sylvioidea neo-sex chromosome. Mol Ecol 2022; 31:3566-3583. [PMID: 35578784 PMCID: PMC9327509 DOI: 10.1111/mec.16532] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/13/2022] [Accepted: 05/04/2022] [Indexed: 12/03/2022]
Abstract
Recombination strongly impacts sequence evolution by affecting the extent of linkage and the efficiency of selection. Here, we study recombination over the Z chromosome in great reed warblers (Acrocephalus arundinaceus) using pedigree‐based linkage mapping. This species has extended Z and W chromosomes (“neo‐sex chromosomes”) formed by a fusion between a part of chromosome 4A and the ancestral sex chromosomes, which provides a unique opportunity to assess recombination and sequence evolution in sex‐linked regions of different ages. We assembled an 87.54 Mbp and 90.19 cM large Z with a small pseudoautosomal region (0.89 Mbp) at one end and the fused Chr4A‐part at the other end of the chromosome. A prominent feature in our data was an extreme variation in male recombination rate along Z with high values at both chromosome ends, but an apparent lack of recombination over a substantial central section, covering 78% of the chromosome. The nonrecombining region showed a drastic loss of genetic diversity and accumulation of repeats compared to the recombining parts. Thus, our data emphasize a key role of recombination in affecting local levels of polymorphism. Nonetheless, the evolutionary rate of genes (dN/dS) did not differ between high and low recombining regions, suggesting that the efficiency of selection on protein‐coding sequences can be maintained also at very low levels of recombination. Finally, the Chr4A‐derived part showed a similar recombination rate as the part of the ancestral Z that did recombine, but its sequence characteristics reflected both its previous autosomal, and current Z‐linked, recombination patterns.
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Affiliation(s)
- Suvi Ponnikas
- Department of Biology, Lund University, Lund, Sweden.,Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Hanna Sigeman
- Department of Biology, Lund University, Lund, Sweden
| | - Max Lundberg
- Department of Biology, Lund University, Lund, Sweden
| | - Bengt Hansson
- Department of Biology, Lund University, Lund, Sweden
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14
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Spottiswoode CN, Tong W, Jamie GA, Stryjewski KF, DaCosta JM, Kuras ER, Green A, Hamama S, Taylor IG, Moya C, Sorenson MD. Genetic architecture facilitates then constrains adaptation in a host-parasite coevolutionary arms race. Proc Natl Acad Sci U S A 2022; 119:e2121752119. [PMID: 35412865 PMCID: PMC9170059 DOI: 10.1073/pnas.2121752119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/11/2022] [Indexed: 12/15/2022] Open
Abstract
In coevolutionary arms races, interacting species impose selection on each other, generating reciprocal adaptations and counter adaptations. This process is typically enhanced by genetic recombination and heterozygosity, but these sources of evolutionary novelty may be secondarily lost when uniparental inheritance evolves to ensure the integrity of sex-linked adaptations. We demonstrate that host-specific egg mimicry in the African cuckoo finch Anomalospiza imberbis is maternally inherited, confirming the validity of an almost century-old hypothesis. We further show that maternal inheritance not only underpins the mimicry of different host species but also additional mimetic diversification that approximates the range of polymorphic egg “signatures” that have evolved within host species as an escalated defense against parasitism. Thus, maternal inheritance has enabled the evolution and maintenance of nested levels of mimetic specialization in a single parasitic species. However, maternal inheritance and the lack of sexual recombination likely disadvantage cuckoo finches by stifling further adaptation in the ongoing arms races with their individual hosts, which we show have retained biparental inheritance of egg phenotypes. The inability to generate novel genetic combinations likely prevents cuckoo finches from mimicking certain host phenotypes that are currently favored by selection (e.g., the olive-green colored eggs laid by some tawny-flanked prinia, Prinia subflava, females). This illustrates an important cost of coding coevolved adaptations on the nonrecombining sex chromosome, which may impede further coevolutionary change by effectively reversing the advantages of sexual reproduction in antagonistic coevolution proposed by the Red Queen hypothesis.
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Affiliation(s)
- Claire N. Spottiswoode
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
- FitzPatrick Institute of African Ornithology, Department of Science and Technology–National Research Foundation Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa
| | - Wenfei Tong
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Gabriel A. Jamie
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
- FitzPatrick Institute of African Ornithology, Department of Science and Technology–National Research Foundation Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa
| | | | - Jeffrey M. DaCosta
- Department of Biology, Boston University, Boston, MA 02215
- Biology Department, Boston College, Chestnut Hill, MA 02467
| | - Evan R. Kuras
- Department of Biology, Boston University, Boston, MA 02215
| | - Ailsa Green
- Chenga Farm, Choma, Southern Province, Zambia
| | - Silky Hamama
- Musumanene Farm, Choma, Southern Province, Zambia
| | | | - Collins Moya
- Musumanene Farm, Choma, Southern Province, Zambia
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15
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Westerdahl H, Mellinger S, Sigeman H, Kutschera VE, Proux-Wéra E, Lundberg M, Weissensteiner M, Churcher A, Bunikis I, Hansson B, Wolf JBW, Strandh M. The genomic architecture of the passerine MHC region: high repeat content and contrasting evolutionary histories of single copy and tandemly duplicated MHC genes. Mol Ecol Resour 2022; 22:2379-2395. [PMID: 35348299 DOI: 10.1111/1755-0998.13614] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 03/09/2022] [Accepted: 03/23/2022] [Indexed: 12/01/2022]
Abstract
The Major Histocompatibility Complex (MHC) is of central importance to the immune system, and an optimal MHC diversity is believed to maximize pathogen elimination. Birds show substantial variation in MHC diversity, ranging from few genes in most bird orders to very many genes in passerines. Our understanding of the evolutionary trajectories of the MHC in passerines is hampered by lack of data on genomic organization. Therefore, we assemble and annotate the MHC genomic region of the great reed warbler (Acrocephalus arundinaceus), using long-read sequencing and optical mapping. The MHC region is large (>5.5Mb), characterized by structural changes compared to hitherto investigated bird orders and shows higher repeat content than the genome average. These features were supported by analyses in three additional passerines. MHC genes in passerines are found in two different chromosomal arrangements, either as single copy MHC genes located among non-MHC genes, or as tandemly duplicated tightly linked MHC genes. Some single copy MHC genes are old and putative orthologs among species. In contrast tandemly duplicated MHC genes are monophyletic within species and have evolved by simultaneous gene duplication of several MHC genes. Structural differences in the MHC genomic region among bird orders seem substantial compared to mammals and have possibly been fuelled by clade-specific immune system adaptations. Our study provides methodological guidance in characterizing complex genomic regions, constitutes a resource for MHC research in birds, and calls for a revision of the general belief that avian MHC has a conserved gene order and small size compared to mammals.
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Affiliation(s)
- Helena Westerdahl
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Samantha Mellinger
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Hanna Sigeman
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Verena E Kutschera
- Department of Biochemistry and Biophysics, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Stockholm University, Box 1031, SE-17121, Solna, Sweden
| | - Estelle Proux-Wéra
- Department of Biochemistry and Biophysics, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Stockholm University, Box 1031, SE-17121, Solna, Sweden
| | - Max Lundberg
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Matthias Weissensteiner
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Grosshaderner Str. 2, 82152, Planegg-Martinsried, Germany
| | - Allison Churcher
- National Bioinformatics Infrastructure Sweden, Department of Molecular Biology, Umeå University, SE-901 87, Umeå, Sweden
| | - Ignas Bunikis
- Uppsala Genome Center, Science for Life Laboratory, Dept. of Immunology, Genetics and Pathology, Uppsala University, BMC, Box 815, SE-752 37, Uppsala, Sweden
| | - Bengt Hansson
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Jochen B W Wolf
- Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Grosshaderner Str. 2, 82152, Planegg-Martinsried, Germany
| | - Maria Strandh
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
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16
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Dynamic Patterns of Sex Chromosome Evolution in Neognath Birds: Many Independent Barriers to Recombination at the ATP5F1A Locus. BIRDS 2022. [DOI: 10.3390/birds3010004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Avian sex chromosomes evolved after the divergence of birds and crocodilians from their common ancestor, so they are younger than the better-studied chromosomes of mammals. It has long been recognized that there may have been several stages to the evolution of avian sex chromosomes. For example, the CHD1 undergoes recombination in paleognaths but not neognaths. Genome assemblies have suggested that there may be variation in the timing of barriers to recombination among Neognathae, but there remains little understanding of the extent of this variability. Here, we look at partial sequences of ATP5F1A, which is on the avian Z and W chromosomes. It is known that recombination of this gene has independently ceased in Galliformes, Anseriformes, and at least five neoavian orders, but whether there are other independent cessations of recombination among Neoaves is not understood. We analyzed a combination of data extracted from published chromosomal-level genomes with data collected using PCR and cloning to identify Z and W copies in 22 orders. Our results suggest that there may be at least 19 independent cessations of recombination within Neognathae, and 3 clades that may still be undergoing recombination (or have only recently ceased recombination). Analyses of ATP5F1A protein sequences revealed an increased amino acid substitution rate for W chromosome gametologs, suggesting relaxed purifying selection on the W chromosome. Supporting this hypothesis, we found that the increased substitution rate was particularly pronounced for buried residues, which are expected to be more strongly constrained by purifying selection. This highlights the dynamic nature of avian sex chromosomes, and that this level of variation among clades means they should be a good system to understand sex chromosome evolution.
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17
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Shakya SB, Wang-Claypool CY, Cicero C, Bowie RCK, Mason NA. Neo-sex chromosome evolution and phenotypic differentiation across an elevational gradient in horned larks (Eremophila Alpestris). Mol Ecol 2022; 31:1783-1799. [PMID: 35048444 DOI: 10.1111/mec.16357] [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: 08/02/2021] [Revised: 12/16/2021] [Accepted: 01/07/2022] [Indexed: 11/29/2022]
Abstract
Genetic structure and phenotypic variation among populations is affected by both geographic distance and environmental variation across species' distributions. Understanding the relative contributions of isolation by distance (IBD) and isolation by environment (IBE) is important for elucidating population dynamics across habitats and ecological gradients. In this study, we compared phenotypic and genetic variation among Horned Lark (Eremophila alpestris) populations from 10 sites encompassing an elevational gradient from low-elevation desert scrub in Death Valley (285 a.s.l.) to high-elevation meadows in the White Mountains of the Sierra Nevada of California (greater than 3000 m a.s.l.). Using a ddRAD dataset of 28,474 SNPs aligned to a high-quality reference genome, we compared genetic structure with elevational, environmental, and spatial distance to quantify how different aspects of the landscape drive genomic and phenotypic differentiation in Horned Larks. We found larger-bodied birds were associated with sites that had less seasonality and higher annual precipitation, and longer spurs occurred in soils with more clay and silt content, less sand, and finer fragments. Larks have large neo-sex chromosomes, and we found that associations with elevation and environmental variation were much stronger among neo-sex chromosomes compared to autosomes. Furthermore, we found that putative chromosomal translocations, fusions, and inversions were associated with elevation and may underlie local adaptation across an elevational gradient in Horned Larks. Our results suggest that genetic variation in Horned Larks is affected more by IBD than IBE, but specific phenotypes and genomic regions-particually on neo-sex chromosomes-bear stronger associations with the environment.
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Affiliation(s)
- Subir B Shakya
- Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Cynthia Y Wang-Claypool
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA.,Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Carla Cicero
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
| | - Rauri C K Bowie
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA.,Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Nicholas A Mason
- Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.,Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
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