1
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Setti PG, Deon GA, Zeni Dos Santos R, Goes CAG, Garnero ADV, Gunski RJ, de Oliveira EHC, Porto-Foresti F, de Freitas TRO, Silva FAO, Liehr T, Utsunomia R, Kretschmer R, de Bello Cioffi M. Evolution of bird sex chromosomes: a cytogenomic approach in Palaeognathae species. BMC Ecol Evol 2024; 24:51. [PMID: 38654159 PMCID: PMC11036779 DOI: 10.1186/s12862-024-02230-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Different patterns of sex chromosome differentiation are seen in Palaeognathae birds, a lineage that includes the ratites (Struthioniformes, Rheiformes, Apterygiformes, Casuariiformes, and the sister group Tinamiformes). While some Tinamiform species have well-differentiated W chromosomes, both Z and W of all the flightless ratites are still morphologically undifferentiated. Here, we conducted a comprehensive analysis of the ZW differentiation in birds using a combination of cytogenetic, genomic, and bioinformatic approaches. The whole set of satDNAs from the emu (Dromaius novaehollandiae) was described and characterized. Furthermore, we examined the in situ locations of these satDNAs alongside several microsatellite repeats and carried out Comparative Genomic Hybridizations in two related species: the greater rhea (Rhea americana) and the tataupa tinamou (Crypturellus tataupa). RESULTS From the 24 satDNA families identified (which represent the greatest diversity of satDNAs ever uncovered in any bird species), only three of them were found to accumulate on the emu's sex chromosomes, with no discernible accumulation observed on the W chromosome. The W chromosomes of both the greater rhea and the emu did not exhibit a significant buildup of either C-positive heterochromatin or repetitive DNAs, indicating their large undifferentiation both at morphological and molecular levels. In contrast, the tataupa tinamou has a highly differentiated W chromosome that accumulates several DNA repeats. CONCLUSION The findings provide new information on the architecture of the avian genome and an inside look at the starting points of sex chromosome differentiation in birds.
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Affiliation(s)
- Príncia Grejo Setti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, 13565-905, São Carlos, SP, Brazil
| | - Geize Aparecida Deon
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, 13565-905, São Carlos, SP, Brazil
| | | | | | - Analía Del Valle Garnero
- Campus São Gabriel, Universidade Federal do Pampa, 97307-020, São Gabriel, Rio Grande do Sul, Brazil
| | - Ricardo José Gunski
- Campus São Gabriel, Universidade Federal do Pampa, 97307-020, São Gabriel, Rio Grande do Sul, Brazil
| | - Edivaldo Herculano Corrêa de Oliveira
- Laboratório de Citogenômica e Mutagênese Ambiental, Seção de Meio Ambiente, Instituto Evandro Chagas, 67030-000, Ananindeua, PA, Brazil
- Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, 66075-110, Belém, PA, Brazil
| | - Fábio Porto-Foresti
- Faculdade de Ciências, Universidade Estadual Paulista, 17033-360, Bauru, São Paulo, Brazil
| | | | - Fábio Augusto Oliveira Silva
- Laboratório de Citogenômica e Mutagênese Ambiental, Seção de Meio Ambiente, Instituto Evandro Chagas, 67030-000, Ananindeua, PA, Brazil
| | - Thomas Liehr
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, 07747, Jena, Germany.
| | - Ricardo Utsunomia
- Faculdade de Ciências, Universidade Estadual Paulista, 17033-360, Bauru, São Paulo, Brazil
| | - Rafael Kretschmer
- Departamento de Ecologia, Zoologia e Genética, Instituto de Biologia, Universidade Federal de Pelotas, 96.010-610, Pelotas, RS, Brazil
| | - Marcelo de Bello Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, 13565-905, São Carlos, SP, Brazil
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2
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Kretschmer R, Toma GA, Deon GA, dos Santos N, dos Santos RZ, Utsunomia R, Porto-Foresti F, Gunski RJ, Garnero ADV, Liehr T, de Oliveira EHC, de Freitas TRO, Cioffi MDB. Satellitome Analysis in the Southern Lapwing ( Vanellus chilensis) Genome: Implications for SatDNA Evolution in Charadriiform Birds. Genes (Basel) 2024; 15:258. [PMID: 38397247 PMCID: PMC10887557 DOI: 10.3390/genes15020258] [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: 01/29/2024] [Revised: 02/14/2024] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
Vanellus (Charadriidae; Charadriiformes) comprises around 20 species commonly referred to as lapwings. In this study, by integrating cytogenetic and genomic approaches, we assessed the satellite DNA (satDNA) composition of one typical species, Vanellus chilensis, with a highly conserved karyotype. We additionally underlined its role in the evolution, structure, and differentiation process of the present ZW sex chromosome system. Seven distinct satellite DNA families were identified within its genome, accumulating on the centromeres, microchromosomes, and the W chromosome. However, these identified satellite DNA families were not found in two other Charadriiformes members, namely Jacana jacana and Calidris canutus. The hybridization of microsatellite sequences revealed the presence of a few repetitive sequences in V. chilensis, with only two out of sixteen displaying positive hybridization signals. Overall, our results contribute to understanding the genomic organization and satDNA evolution in Charadriiform birds.
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Affiliation(s)
- Rafael Kretschmer
- Departamento de Ecologia, Zoologia e Genética, Universidade Federal de Pelotas, Pelotas 96010-900, RS, Brazil;
| | - Gustavo A. Toma
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, SP, Brazil; (G.A.T.); (G.A.D.); (M.d.B.C.)
| | - Geize Aparecida Deon
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, SP, Brazil; (G.A.T.); (G.A.D.); (M.d.B.C.)
| | - Natalia dos Santos
- Faculdade de Ciências, Universidade Estadual Paulista, Bauru 13506-900, SP, Brazil; (N.d.S.); (R.Z.d.S.); (R.U.); (F.P.-F.)
| | - Rodrigo Zeni dos Santos
- Faculdade de Ciências, Universidade Estadual Paulista, Bauru 13506-900, SP, Brazil; (N.d.S.); (R.Z.d.S.); (R.U.); (F.P.-F.)
| | - Ricardo Utsunomia
- Faculdade de Ciências, Universidade Estadual Paulista, Bauru 13506-900, SP, Brazil; (N.d.S.); (R.Z.d.S.); (R.U.); (F.P.-F.)
| | - Fabio Porto-Foresti
- Faculdade de Ciências, Universidade Estadual Paulista, Bauru 13506-900, SP, Brazil; (N.d.S.); (R.Z.d.S.); (R.U.); (F.P.-F.)
| | - Ricardo José Gunski
- Laboratório de Diversidade Genética Animal, Universidade Federal do Pampa, São Gabriel 97300-162, RS, Brazil; (R.J.G.); (A.D.V.G.)
| | - Analía Del Valle Garnero
- Laboratório de Diversidade Genética Animal, Universidade Federal do Pampa, São Gabriel 97300-162, RS, Brazil; (R.J.G.); (A.D.V.G.)
| | - Thomas Liehr
- Institute of Human Genetics, Friedrich Schiller University, University Hospital Jena, 07747 Jena, Germany
| | - Edivaldo Herculano Corra de Oliveira
- Laboratório de Citogenô mica e Mutagênese Ambiental, Seção de Meio Ambiente, Instituto Evandro Chagas, Ananindeua 67030-000, PA, Brazil;
- Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, Belém 66075-110, PA, Brazil
| | - Thales Renato Ochotorena de Freitas
- Laboratório de Citogenética e Evolução, Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91509-900, RS, Brazil;
| | - Marcelo de Bello Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, SP, Brazil; (G.A.T.); (G.A.D.); (M.d.B.C.)
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3
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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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4
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Yazdi HP, Olito C, Kawakami T, Unneberg P, Schou MF, Cloete SWP, Hansson B, Cornwallis CK. The evolutionary maintenance of ancient recombining sex chromosomes in the ostrich. PLoS Genet 2023; 19:e1010801. [PMID: 37390104 DOI: 10.1371/journal.pgen.1010801] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 05/28/2023] [Indexed: 07/02/2023] Open
Abstract
Sex chromosomes have evolved repeatedly across the tree of life and often exhibit extreme size dimorphism due to genetic degeneration of the sex-limited chromosome (e.g. the W chromosome of some birds and Y chromosome of mammals). However, in some lineages, ancient sex-limited chromosomes have escaped degeneration. Here, we study the evolutionary maintenance of sex chromosomes in the ostrich (Struthio camelus), where the W remains 65% the size of the Z chromosome, despite being more than 100 million years old. Using genome-wide resequencing data, we show that the population scaled recombination rate of the pseudoautosomal region (PAR) is higher than similar sized autosomes and is correlated with pedigree-based recombination rate in the heterogametic females, but not homogametic males. Genetic variation within the sex-linked region (SLR) (π = 0.001) was significantly lower than in the PAR, consistent with recombination cessation. Conversely, genetic variation across the PAR (π = 0.0016) was similar to that of autosomes and dependent on local recombination rates, GC content and to a lesser extent, gene density. In particular, the region close to the SLR was as genetically diverse as autosomes, likely due to high recombination rates around the PAR boundary restricting genetic linkage with the SLR to only ~50Kb. The potential for alleles with antagonistic fitness effects in males and females to drive chromosome degeneration is therefore limited. While some regions of the PAR had divergent male-female allele frequencies, suggestive of sexually antagonistic alleles, coalescent simulations showed this was broadly consistent with neutral genetic processes. Our results indicate that the degeneration of the large and ancient sex chromosomes of the ostrich may have been slowed by high recombination in the female PAR, reducing the scope for the accumulation of sexually antagonistic variation to generate selection for recombination cessation.
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Affiliation(s)
| | - Colin Olito
- Department of Biology, Lund University, Lund, Sweden
| | - Takeshi Kawakami
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Embark Veterinary, Inc., Boston, Massachusetts, United States of America
| | - Per Unneberg
- Department of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Mads F Schou
- Department of Biology, Lund University, Lund, Sweden
| | - Schalk W P Cloete
- Directorate Animal Sciences, Western Cape Department of Agriculture, Elsenburg, South Africa
- Department of Animal Sciences, Stellenbosch University, Matieland, South Africa
| | - Bengt Hansson
- Department of Biology, Lund University, Lund, Sweden
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5
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Peona V, Kutschera VE, Blom MPK, Irestedt M, Suh A. Satellite DNA evolution in Corvoidea inferred from short and long reads. Mol Ecol 2023; 32:1288-1305. [PMID: 35488497 DOI: 10.1111/mec.16484] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/11/2022] [Accepted: 04/17/2022] [Indexed: 11/29/2022]
Abstract
Satellite DNA (satDNA) is a fast-evolving portion of eukaryotic genomes. The homogeneous and repetitive nature of such satDNA causes problems during the assembly of genomes, and therefore it is still difficult to study it in detail in nonmodel organisms as well as across broad evolutionary timescales. Here, we combined the use of short- and long-read data to explore the diversity and evolution of satDNA between individuals of the same species and between genera of birds spanning ~40 millions of years of bird evolution using birds-of-paradise (Paradisaeidae) and crow (Corvus) species. These avian species highlighted the presence of a GC-rich Corvoidea satellitome composed of 61 satellite families and provided a set of candidate satDNA monomers for being centromeric on the basis of length, abundance, homogeneity and transcription. Surprisingly, we found that the satDNA of crow species rapidly diverged between closely related species while the satDNA appeared more similar between birds-of-paradise species belonging to different genera.
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Affiliation(s)
- Valentina Peona
- Department of Organismal Biology - Systematic Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Verena E Kutschera
- Department of Biochemistry and Biophysics, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Mozes P K Blom
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Stockholm, Sweden.,Museum für Naturkunde, Leibniz Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Martin Irestedt
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, Stockholm, Sweden
| | - Alexander Suh
- Department of Organismal Biology - Systematic Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,School of Biological Sciences-Organisms and the Environment, University of East Anglia, Norwich, UK
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6
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The Length Polymorphism of the 9th Intron in the Avian CHD1 Gene Allows Sex Determination in Some Species of Palaeognathae. Genes (Basel) 2022; 13:genes13030507. [PMID: 35328061 PMCID: PMC8954394 DOI: 10.3390/genes13030507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 11/30/2022] Open
Abstract
In palaeognathous birds, several PCR-based methods and a range of genes and unknown genomic regions have been studied for the determination of sex. Many of these methods have proven to be unreliable, complex, expensive, and time-consuming. Even the most widely used PCR markers for sex typing in birds, the selected introns of the highly conserved CHD1 gene (primers P2/P8, 1237L/1272H, and 2550F/2718R), have rarely been effective in palaeognathous birds. In this study we used eight species of Palaeognathae to test three PCR markers: CHD1i9 (CHD1 gene intron 9) and NIPBLi16 (NIPBL gene intron 16) that performed properly as Psittaciformes sex differentiation markers, but have not yet been tested in Palaeognathae, as well as the CHD1iA intron (CHD1 gene intron 16), which so far has not been used effectively to sex palaeognathous birds. The results of our research indicate that the CHD1i9 marker effectively differentiates sex in four of the eight species we studied. In Rhea americana, Eudromia elegans, and Tinamus solitarius, the electrophoretic patterns of the amplicons obtained clearly indicate the sex of tested individuals, whereas in Crypturellus tataupa, sexing is possible based on poorly visible female specific bands. Additionally, we present and discuss the results of our in silico investigation on the applicability of CHD1i9 to sex other Palaeognathae that were not tested in this study.
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7
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Okuno M, Mizushima S, Kuroiwa A, Itoh T. Analysis of Sex Chromosome Evolution in the Clade Palaeognathae from Phased Genome Assembly. Genome Biol Evol 2021; 13:6413640. [PMID: 34718546 PMCID: PMC8599748 DOI: 10.1093/gbe/evab242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2021] [Indexed: 12/30/2022] Open
Abstract
Birds in the clade Palaeognathae, excluding Tinamiformes, have morphologically conserved karyotypes and less differentiated ZW sex chromosomes compared with those of other birds. In particular, the sex chromosomes of the ostrich and emu have exceptionally large recombining pseudoautosomal regions (PARs), whereas non-PARs are classified into two strata according to the date of their origins: stratum 0 and stratum 1 (S1). However, the construction and analysis of the genome sequences in these regions in the clade Palaeognathae can be challenging because assembling the S1 region is difficult owing to low sequence diversity between gametologs (Z-linked and W-linked sequences). We addressed this issue by applying the Platanus-allee assembler and successfully constructed the haplotype-resolved (phased) assembly for female emu, cassowary, and ostrich using only sequence read data derived from the Illumina platform. Comparative genomic and phylogenetic analyses based on assembled Z-linked and W-linked sequences confirmed that the S1 region of emu and cassowary formed in their common ancestor. Moreover, the interspersed repetitive sequence landscapes in the S1 regions of female emu showed an expansion of younger repetitive elements in the W-linked S1 region, suggesting an interruption in homologous recombination in the S1 region. These results provide novel insights into the trajectory of sex chromosome evolution in the clade Palaeognathae and suggest that the Illumina-based phased assembly method is an effective approach for elucidating the evolutionary process underlying the transition from homomorphic to differentiated sex chromosomes.
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Affiliation(s)
- Miki Okuno
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.,Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka, Japan
| | - Shusei Mizushima
- Division of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Asato Kuroiwa
- Division of Reproductive and Developmental Biology, Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Takehiko Itoh
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan
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8
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Mazzoleni S, Němec P, Albrecht T, Lymberakis P, Kratochvíl L, Rovatsos M. Long-term stability of sex chromosome gene content allows accurate qPCR-based molecular sexing across birds. Mol Ecol Resour 2021; 21:2013-2021. [PMID: 33720488 DOI: 10.1111/1755-0998.13381] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/13/2021] [Accepted: 03/08/2021] [Indexed: 12/14/2022]
Abstract
Embryos, juveniles, and even adults of many bird species lack pronounced external sexually dimorphic characteristics. Accurate identification of sex is crucial for research (e.g., developmental, population, and evolutionary studies), management of wildlife species, and captive breeding programmes for both conservation and poultry. An accurate molecular sexing method applicable across the entire bird radiation is theoretically possible thanks to the long-term stability of their ZZ/ZW sex chromosomes, but current methods are not applicable in a wide range of bird lineages. Here, we developed a novel molecular sexing method based on the comparison of gene copy number variation by quantitative real-time PCR (qPCR) in conserved Z-specific genes (CHRNA6, DDX4, LPAR1, TMEM161B, VPS13A), i.e. genes linked to Z but absent from W chromosomes. We tested the method across three paleognath and 70 neognath species covering the avian phylogeny. In addition, we designed primers for four Z-specific genes (DOCK8, FUT10, PIGG and PSD3) for qPCR-based molecular sexing in three paleognath species. We have demonstrated that the genes DOCK8, FUT10, PIGG and PSD3 can identify sex in paleognath birds and the genes CHRNA6, DDX4, TMEM161B, and VPS13A can reveal sex in neognath birds. The gene LPAR1 can be used to accurately identify sex in both paleognath and neognath species. Along with outlining a novel method of practical importance for molecular sexing in birds, our study also documents in detail the conservation of sex chromosomes across the avian phylogeny.
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Affiliation(s)
- Sofia Mazzoleni
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Pavel Němec
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Tomáš Albrecht
- Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic.,Institute of Vertebrate Biology, Czech Academy of Sciences, Brno, Czech Republic
| | - Petros Lymberakis
- Natural History Museum of Crete, University of Crete, Irakleio, Greece
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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9
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Wang ZJ, Chen GJ, Zhang GJ, Zhou Q. Dynamic evolution of transposable elements, demographic history, and gene content of paleognathous birds. Zool Res 2021; 42:51-61. [PMID: 33124220 PMCID: PMC7840455 DOI: 10.24272/j.issn.2095-8137.2020.175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Palaeognathae includes ratite and tinamou species that are important for understanding early avian evolution. Here, we analyzed the whole-genome sequences of 15 paleognathous species to infer their demographic histories, which are presently unknown. We found that most species showed a reduction of population size since the beginning of the last glacial period, except for those species distributed in Australasia and in the far south of South America. Different degrees of contraction and expansion of transposable elements (TE) have shaped the paleognathous genome architecture, with a higher transposon removal rate in tinamous than in ratites. One repeat family, AviRTE, likely underwent horizontal transfer from tropical parasites to the ancestor of little and undulated tinamous about 30 million years ago. Our analysis of gene families identified rapid turnover of immune and reproduction-related genes but found no evidence of gene family changes underlying the convergent evolution of flightlessness among ratites. We also found that mitochondrial genes have experienced a faster evolutionary rate in tinamous than in ratites, with the former also showing more degenerated W chromosomes. This result can be explained by the Hill-Robertson interference affecting genetically linked W chromosomes and mitochondria. Overall, we reconstructed the evolutionary history of the Palaeognathae populations, genes, and TEs. Our findings of co-evolution between mitochondria and W chromosomes highlight the key difference in genome evolution between species with ZW sex chromosomes and those with XY sex chromosomes.
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Affiliation(s)
- Zong-Ji Wang
- Institute of Animal Sex and Development, Zhejiang Wanli University, Ningbo, Zhejiang 315100, China.,MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Department of Neuroscience and Developmental Biology, University of Vienna, Vienna 1090, Austria.,BGI-Shenzhen, Beishan Industrial Zone, Shenzhen, Guangdong 518083, China
| | - Guang-Ji Chen
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen, Guangdong 518083, China
| | - Guo-Jie Zhang
- BGI-Shenzhen, Beishan Industrial Zone, Shenzhen, Guangdong 518083, China.,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China.,Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, Yunnan 650223, China. E-mail:
| | - Qi Zhou
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Department of Neuroscience and Developmental Biology, University of Vienna, Vienna 1090, Austria.,Center for Reproductive Medicine, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China. E-mail:
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10
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Yazdi HP, Silva WTAF, Suh A. Why Do Some Sex Chromosomes Degenerate More Slowly Than Others? The Odd Case of Ratite Sex Chromosomes. Genes (Basel) 2020; 11:E1153. [PMID: 33007827 PMCID: PMC7601716 DOI: 10.3390/genes11101153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 01/10/2023] Open
Abstract
The hallmark of sex chromosome evolution is the progressive suppression of recombination which leads to subsequent degeneration of the non-recombining chromosome. In birds, species belonging to the two major clades, Palaeognathae (including tinamous and flightless ratites) and Neognathae (all remaining birds), show distinctive patterns of sex chromosome degeneration. Birds are female heterogametic, in which females have a Z and a W chromosome. In Neognathae, the highly-degenerated W chromosome seems to have followed the expected trajectory of sex chromosome evolution. In contrast, among Palaeognathae, sex chromosomes of ratite birds are largely recombining. The underlying reason for maintenance of recombination between sex chromosomes in ratites is not clear. Degeneration of the W chromosome might have halted or slowed down due to a multitude of reasons ranging from selective processes, such as a less pronounced effect of sexually antagonistic selection, to neutral processes, such as a slower rate of molecular evolution in ratites. The production of genome assemblies and gene expression data for species of Palaeognathae has made it possible, during recent years, to have a closer look at their sex chromosome evolution. Here, we critically evaluate the understanding of the maintenance of recombination in ratites in light of the current data. We conclude by highlighting certain aspects of sex chromosome evolution in ratites that require further research and can potentially increase power for the inference of the unique history of sex chromosome evolution in this lineage of birds.
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Affiliation(s)
| | | | - Alexander Suh
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TU, UK;
- Department of Organismal Biology—Systematic Biology, Uppsala University, SE-752 36 Uppsala, Sweden
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11
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Suntronpong A, Singchat W, Kruasuwan W, Prakhongcheep O, Sillapaprayoon S, Muangmai N, Somyong S, Indananda C, Kraichak E, Peyachoknagul S, Srikulnath K. Characterization of centromeric satellite DNAs (MALREP) in the Asian swamp eel (Monopterus albus) suggests the possible origin of repeats from transposable elements. Genomics 2020; 112:3097-3107. [PMID: 32470643 DOI: 10.1016/j.ygeno.2020.05.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 04/21/2020] [Accepted: 05/24/2020] [Indexed: 01/04/2023]
Abstract
Centromeric satellite DNA (cen-satDNA) sequences of the Asian swamp eel (Monopterus albus) were characterized. Three GC-rich cen-satDNA sequences were detected as a 233 bp MALREP-A and a 293 bp MALREP-B localized to all chromosomes, and a 293 bp MALREP-C distributed on eight chromosome pairs. Sequence lengths of MALREP-B and MALREP-C were 60 bp larger than that of MALREP-A, showing partial homology with core sequences (233 bp). Size differences between MALREP-A and MALREP-B/C suggest the possible occurrence of two satDNA families. The presence of an additional 60 bp in MALREP-B/C resulted from an ancient dimer of 233 bp monomers and subsequent mutation and homogenization between the two monomers. All MALREPs showed partial homology with transposable elements (TEs), suggesting that the MALREPs originated from the TEs. The MALREPs might have been acquired in the Asian swamp eel, thereby promoting fixation in the species.
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Affiliation(s)
- Aorarat Suntronpong
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; Special Research Unit for Wildlife Genomics, Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
| | - Worapong Singchat
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; Special Research Unit for Wildlife Genomics, Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
| | - Worarat Kruasuwan
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
| | - Ornjira Prakhongcheep
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
| | - Siwapech Sillapaprayoon
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; Special Research Unit for Wildlife Genomics, Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand.
| | - Narongrit Muangmai
- Department of Fishery Biology, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand.
| | - Suthasinee Somyong
- National Omics Center, National Center for Genetic Engineering and Biotechnology (BIOTEC), Pathum Thani 12120, Thailand.
| | - Chantra Indananda
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
| | - Ekaphan Kraichak
- Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
| | - Surin Peyachoknagul
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.
| | - Kornsorn Srikulnath
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; Special Research Unit for Wildlife Genomics, Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand; Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University, Kasetsart University, Bangkok 10900, Thailand; Center of Excellence on Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok 10900, Thailand; Omics Center for Agriculture, Bioresources, Food and Health, Kasetsart University (OmiKU), Bangkok 10900, Thailand; Amphibian Research Center, Hiroshima University, 1-3-1, Kagamiyama, Higashihiroshima 739-8526, Japan.
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12
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Xu L, Wa Sin SY, Grayson P, Edwards SV, Sackton TB. Evolutionary Dynamics of Sex Chromosomes of Paleognathous Birds. Genome Biol Evol 2020; 11:2376-2390. [PMID: 31329234 PMCID: PMC6735826 DOI: 10.1093/gbe/evz154] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2019] [Indexed: 12/20/2022] Open
Abstract
Standard models of sex chromosome evolution propose that recombination suppression leads to the degeneration of the heterogametic chromosome, as is seen for the Y chromosome in mammals and the W chromosome in most birds. Unlike other birds, paleognaths (ratites and tinamous) possess large nondegenerate regions on their sex chromosomes (PARs or pseudoautosomal regions). It remains unclear why these large PARs are retained over >100 Myr, and how this retention impacts the evolution of sex chromosomes within this system. To address this puzzle, we analyzed Z chromosome evolution and gene expression across 12 paleognaths, several of whose genomes have recently been sequenced. We confirm at the genomic level that most paleognaths retain large PARs. As in other birds, we find that all paleognaths have incomplete dosage compensation on the regions of the Z chromosome homologous to degenerated portions of the W (differentiated regions), but we find no evidence for enrichments of male-biased genes in PARs. We find limited evidence for increased evolutionary rates (faster-Z) either across the chromosome or in differentiated regions for most paleognaths with large PARs, but do recover signals of faster-Z evolution in tinamou species with mostly degenerated W chromosomes, similar to the pattern seen in neognaths. Unexpectedly, in some species, PAR-linked genes evolve faster on average than genes on autosomes, suggested by diverse genomic features to be due to reduced efficacy of selection in paleognath PARs. Our analysis shows that paleognath Z chromosomes are atypical at the genomic level, but the evolutionary forces maintaining largely homomorphic sex chromosomes in these species remain elusive.
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Affiliation(s)
- Luohao Xu
- Department of Molecular Evolution and Development, University of Vienna, Austria
| | - Simon Yung Wa Sin
- Department of Organismic and Evolutionary Biology, Harvard University
- Museum of Comparative Zoology, Harvard University
- School of Biological Sciences, The University of Hong Kong, Hong Kong
| | - Phil Grayson
- Department of Organismic and Evolutionary Biology, Harvard University
- Museum of Comparative Zoology, Harvard University
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology, Harvard University
- Museum of Comparative Zoology, Harvard University
| | - Timothy B Sackton
- Informatics Group, Division of Science, Harvard University
- Corresponding author: E-mail:
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13
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Ezaz T, Srikulnath K, Graves JAM. Origin of Amniote Sex Chromosomes: An Ancestral Super-Sex Chromosome, or Common Requirements? J Hered 2016; 108:94-105. [DOI: 10.1093/jhered/esw053] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 08/22/2016] [Indexed: 12/28/2022] Open
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14
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Deakin JE, Edwards MJ, Patel H, O'Meally D, Lian J, Stenhouse R, Ryan S, Livernois AM, Azad B, Holleley CE, Li Q, Georges A. Anchoring genome sequence to chromosomes of the central bearded dragon (Pogona vitticeps) enables reconstruction of ancestral squamate macrochromosomes and identifies sequence content of the Z chromosome. BMC Genomics 2016; 17:447. [PMID: 27286959 PMCID: PMC4902969 DOI: 10.1186/s12864-016-2774-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/25/2016] [Indexed: 12/30/2022] Open
Abstract
Background Squamates (lizards and snakes) are a speciose lineage of reptiles displaying considerable karyotypic diversity, particularly among lizards. Understanding the evolution of this diversity requires comparison of genome organisation between species. Although the genomes of several squamate species have now been sequenced, only the green anole lizard has any sequence anchored to chromosomes. There is only limited gene mapping data available for five other squamates. This makes it difficult to reconstruct the events that have led to extant squamate karyotypic diversity. The purpose of this study was to anchor the recently sequenced central bearded dragon (Pogona vitticeps) genome to chromosomes to trace the evolution of squamate chromosomes. Assigning sequence to sex chromosomes was of particular interest for identifying candidate sex determining genes. Results By using two different approaches to map conserved blocks of genes, we were able to anchor approximately 42 % of the dragon genome sequence to chromosomes. We constructed detailed comparative maps between dragon, anole and chicken genomes, and where possible, made broader comparisons across Squamata using cytogenetic mapping information for five other species. We show that squamate macrochromosomes are relatively well conserved between species, supporting findings from previous molecular cytogenetic studies. Macrochromosome diversity between members of the Toxicofera clade has been generated by intrachromosomal, and a small number of interchromosomal, rearrangements. We reconstructed the ancestral squamate macrochromosomes by drawing upon comparative cytogenetic mapping data from seven squamate species and propose the events leading to the arrangements observed in representative species. In addition, we assigned over 8 Mbp of sequence containing 219 genes to the Z chromosome, providing a list of genes to begin testing as candidate sex determining genes. Conclusions Anchoring of the dragon genome has provided substantial insight into the evolution of squamate genomes, enabling us to reconstruct ancestral macrochromosome arrangements at key positions in the squamate phylogeny, demonstrating that fusions between macrochromosomes or fusions of macrochromosomes and microchromosomes, have played an important role during the evolution of squamate genomes. Assigning sequence to the sex chromosomes has identified NR5A1 as a promising candidate sex determining gene in the dragon. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2774-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Janine E Deakin
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.
| | - Melanie J Edwards
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Hardip Patel
- John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601, Australia
| | - Denis O'Meally
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Jinmin Lian
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518083, China
| | - Rachael Stenhouse
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Sam Ryan
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Alexandra M Livernois
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Bhumika Azad
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia.,John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601, Australia
| | - Clare E Holleley
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Qiye Li
- China National GeneBank, BGI-Shenzhen, Shenzhen, 518083, China.,Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, Copenhagen, 1350, Denmark
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
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15
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Gorelick R, Fraser D, Mansfield M, Dawson JW, Wijenayake S, Bertram SM. Abrupt shortening of bird W chromosomes in ancestral Neognathae. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12832] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Root Gorelick
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
- School of Mathematics & Statistics and Institute of Interdisciplinary Studies; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
| | - Danielle Fraser
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
| | - Melissa Mansfield
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
| | - Jeff W. Dawson
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
| | - Sanoji Wijenayake
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
| | - Susan M. Bertram
- Department of Biology; Carleton University; 1125 Raven Road Ottawa Ontario K1S 5B6 Canada
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16
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Sixteen kiwi (Apteryx spp) transcriptomes provide a wealth of genetic markers and insight into sex chromosome evolution in birds. BMC Genomics 2016; 17:410. [PMID: 27230888 PMCID: PMC4882810 DOI: 10.1186/s12864-016-2714-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 05/07/2016] [Indexed: 01/08/2023] Open
Abstract
Background Kiwi represent the most basal extant avian lineage (paleognaths) and exhibit biological attributes that are unusual or extreme among living birds, such as large egg size, strong olfaction, nocturnality, flightlessness and long lifespan. Despite intense interest in their evolution and their threatened status, genomic resources for kiwi were virtually non-existent until the recent publication of a single genome. Here we present the most comprehensive kiwi transcriptomes to date, obtained via Illumina sequencing of whole blood and de novo assembly of mRNA sequences of eight individuals from each of the two rarest kiwi species, little spotted kiwi (LSK; Apteryx owenii) and rowi (A. rowi). Results Sequences obtained were orthologous with a wide diversity of functional genes despite the sequencing of a single tissue type. Individual and composite assemblies contain more than 7900 unique protein coding transcripts in each of LSK and rowi that show strong homology with chicken (Gallus gallus), including those associated with growth, development, disease resistance, reproduction and behavior. The assemblies also contain 66,909 SNPs that distinguish between LSK and rowi, 12,384 SNPs among LSK (associated with 3088 genes), and 29,313 SNPs among rowi (associated with 4953 genes). We found 3084 transcripts differentially expressed between LSK and rowi and 150 transcripts differentially expressed between the sexes. Of the latter, 83 could be mapped to chicken chromosomes with 95% syntenic with chromosome Z. Conclusions Our study has simultaneously sequenced multiple species, sexes, and individual kiwi at thousands of genes, and thus represents a significant leap forward in genomic resources available for kiwi. The expression pattern we observed among chromosome Z related genes in kiwi is similar to that observed in ostriches and emu, suggesting a common and ancestral pattern of sex chromosome homomorphy, recombination, and gene dosage among living paleognaths. The transcriptome assemblies described here will provide a rich resource for polymorphic marker development and studies of adaptation of these highly unusual and endangered birds. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2714-2) contains supplementary material, which is available to authorized users.
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17
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Dynamics of vertebrate sex chromosome evolution: from equal size to giants and dwarfs. Chromosoma 2015; 125:553-71. [DOI: 10.1007/s00412-015-0569-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 11/26/2022]
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18
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Zhang J, Li C, Zhou Q, Zhang G. Improving the ostrich genome assembly using optical mapping data. Gigascience 2015; 4:24. [PMID: 25969728 PMCID: PMC4427950 DOI: 10.1186/s13742-015-0062-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/19/2015] [Indexed: 11/10/2022] Open
Abstract
Background The ostrich (Struthio camelus) is the tallest and heaviest living bird. Ostrich meat is considered a healthy red meat, with an annual worldwide production ranging from 12,000 to 15,000 tons. As part of the avian phylogenomics project, we sequenced the ostrich genome for phylogenetic and comparative genomics analyses. The initial Illumina-based assembly of this genome had a scaffold N50 of 3.59 Mb and a total size of 1.23 Gb. Since longer scaffolds are critical for many genomic analyses, particularly for chromosome-level comparative analysis, we generated optical mapping (OM) data to obtain an improved assembly. The OM technique is a non-PCR-based method to generate genome-wide restriction enzyme maps, which improves the quality of de novo genome assembly. Findings In order to generate OM data, we digested the ostrich genome with KpnI, which yielded 1.99 million DNA molecules (>250 kb) and covered the genome at least 500×. The pattern of molecules was subsequently assembled to align with the Illumina-based assembly to achieve sequence extension. This resulted in an OM assembly with a scaffold N50 of 17.71 Mb, which is 5 times as large as that of the initial assembly. The number of scaffolds covering 90% of the genome was reduced from 414 to 75, which means an average of ~3 super-scaffolds for each chromosome. Upon integrating the OM data with previously published FISH (fluorescence in situ hybridization) markers, we recovered the full PAR (pseudoatosomal region) on the ostrich Z chromosome with 4 super-scaffolds, as well as most of the degenerated regions. Conclusions The OM data significantly improved the assembled scaffolds of the ostrich genome and facilitated chromosome evolution studies in birds. Similar strategies can be applied to other genome sequencing projects to obtain better assemblies.
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Affiliation(s)
- Jilin Zhang
- China National GeneBank, BGI-Shenzhen, Shenzhen,, 518083 China
| | - Cai Li
- China National GeneBank, BGI-Shenzhen, Shenzhen,, 518083 China ; Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
| | - Qi Zhou
- Department of Integrative Biology, University of California, Berkeley, USA
| | - Guojie Zhang
- China National GeneBank, BGI-Shenzhen, Shenzhen,, 518083 China ; Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, DK Denmark
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19
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Wang Z, Zhang J, Yang W, An N, Zhang P, Zhang G, Zhou Q. Temporal genomic evolution of bird sex chromosomes. BMC Evol Biol 2014; 14:250. [PMID: 25527260 PMCID: PMC4272511 DOI: 10.1186/s12862-014-0250-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 11/20/2014] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Sex chromosomes exhibit many unusual patterns in sequence and gene expression relative to autosomes. Birds have evolved a female heterogametic sex system (male ZZ, female ZW), through stepwise suppression of recombination between chrZ and chrW. To address the broad patterns and complex driving forces of Z chromosome evolution, we analyze here 45 newly available bird genomes and four species' transcriptomes, over their course of recombination loss between the sex chromosomes. RESULTS We show Z chromosomes in general have a significantly higher substitution rate in introns and synonymous protein-coding sites than autosomes, driven by the male-to-female mutation bias ('male-driven evolution' effect). Our genome-wide estimate reveals that the degree of such a bias ranges from 1.6 to 3.8 among different species. G + C content of third codon positions exhibits the same trend of gradual changes with that of introns, between chrZ and autosomes or regions with increasing ages of becoming Z-linked, therefore codon usage bias in birds is probably driven by the mutational bias. On the other hand, Z chromosomes also evolve significantly faster at nonsynonymous sites relative to autosomes ('fast-Z' evolution). And species with a lower level of intronic heterozygosities tend to evolve even faster on the Z chromosome. Further analysis of fast-evolving genes' enriched functional categories and sex-biased expression patterns support that, fast-Z evolution in birds is mainly driven by genetic drift. Finally, we show in species except for chicken, gene expression becomes more male-biased within Z-linked regions that have became hemizygous in females for a longer time, suggesting a lack of global dosage compensation in birds, and the reported regional dosage compensation in chicken has only evolved very recently. CONCLUSIONS In conclusion, we uncover that the sequence and expression patterns of Z chromosome genes covary with their ages of becoming Z-linked. In contrast to the mammalian X chromosomes, such patterns are mainly driven by mutational bias and genetic drift in birds, due to the opposite sex-biased inheritance of Z vs. X.
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Affiliation(s)
- Zongji Wang
- />School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, 510006 China
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
| | - Jilin Zhang
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
| | - Wei Yang
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
| | - Na An
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
| | - Pei Zhang
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
| | - Guojie Zhang
- />China National GeneBank, BGI-Shenzhen, Shenzhen, 518083 China
- />Department of Biology, Centre for Social Evolution, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
| | - Qi Zhou
- />Department of Integrative Biology, University of California, Berkeley, CA94720 USA
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20
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Zhou Q, Zhang J, Bachtrog D, An N, Huang Q, Jarvis ED, Gilbert MTP, Zhang G. Complex evolutionary trajectories of sex chromosomes across bird taxa. Science 2014; 346:1246338. [PMID: 25504727 DOI: 10.1126/science.1246338] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Sex-specific chromosomes, like the W of most female birds and the Y of male mammals, usually have lost most genes owing to a lack of recombination. We analyze newly available genomes of 17 bird species representing the avian phylogenetic range, and find that more than half of them do not have as fully degenerated W chromosomes as that of chicken. We show that avian sex chromosomes harbor tremendous diversity among species in their composition of pseudoautosomal regions and degree of Z/W differentiation. Punctuated events of shared or lineage-specific recombination suppression have produced a gradient of "evolutionary strata" along the Z chromosome, which initiates from the putative avian sex-determining gene DMRT1 and ends at the pseudoautosomal region. W-linked genes are subject to ongoing functional decay after recombination was suppressed, and the tempo of degeneration slows down in older strata. Overall, we unveil a complex history of avian sex chromosome evolution.
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Affiliation(s)
- Qi Zhou
- Department of Integrative Biology, University of California, Berkeley, CA94720, USA.
| | - Jilin Zhang
- China National Genebank, BGI-Shenzhen, Shenzhen, 518083. China
| | - Doris Bachtrog
- Department of Integrative Biology, University of California, Berkeley, CA94720, USA
| | - Na An
- China National Genebank, BGI-Shenzhen, Shenzhen, 518083. China
| | - Quanfei Huang
- China National Genebank, BGI-Shenzhen, Shenzhen, 518083. China
| | - Erich D Jarvis
- Department of Neurobiology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - M Thomas P Gilbert
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark. Trace and Environmental DNA laboratory, Department of Environment and Agriculture, Curtin University, Perth, Western Australia 6102, Australia
| | - Guojie Zhang
- China National Genebank, BGI-Shenzhen, Shenzhen, 518083. China. Centre for Social Evolution, Department of Biology, Universitetsparken 15, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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21
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Abstract
Retroposon presence/absence patterns in orthologous genomic loci are known to be strong and almost homoplasy-free phylogenetic markers of common ancestry. This is evidenced by the comprehensive reconstruction of various species trees of vertebrate lineages in recent years, as well as the inference of the evolution of genes via retroposon-based gene trees of paralogous genes. Recently, it has been shown that retroposon markers are also suitable for the inference of differentiation events of gametologous genes, i.e., homologous genes on opposite sex chromosomes. This is because sex chromosomes evolved via stepwise cessation of recombination, making the presence or absence of a particular retroposon insertion among the two different gametologs in more or less closely related species a clear-cut indicator of the timing of differentiation events. Here, I examine the advantages and current limitations of this novel perspective for understanding avian sex chromosome evolution, compare the retroposon-based and sequence-based insights into gametolog differentiation and show that retroposons promise to be equally applicable to other sex chromosomal systems, such as the human X and Y chromosomes.
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Affiliation(s)
- Alexander Suh
- Institute of Experimental Pathology (ZMBE); University of Münster; Münster, Germany
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22
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Wright AE, Harrison PW, Montgomery SH, Pointer MA, Mank JE. Independent stratum formation on the avian sex chromosomes reveals inter-chromosomal gene conversion and predominance of purifying selection on the W chromosome. Evolution 2014; 68:3281-95. [PMID: 25066800 PMCID: PMC4278454 DOI: 10.1111/evo.12493] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 07/15/2014] [Indexed: 12/27/2022]
Abstract
We used a comparative approach spanning three species and 90 million years to study the evolutionary history of the avian sex chromosomes. Using whole transcriptomes, we assembled the largest cross-species dataset of W-linked coding content to date. Our results show that recombination suppression in large portions of the avian sex chromosomes has evolved independently, and that long-term sex chromosome divergence is consistent with repeated and independent inversions spreading progressively to restrict recombination. In contrast, over short-term periods we observe heterogeneous and locus-specific divergence. We also uncover four instances of gene conversion between both highly diverged and recently evolved gametologs, suggesting a complex mosaic of recombination suppression across the sex chromosomes. Lastly, evidence from 16 gametologs reveal that the W chromosome is evolving with a significant contribution of purifying selection, consistent with previous findings that W-linked genes play an important role in encoding sex-specific fitness.
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Affiliation(s)
- Alison E Wright
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, OX1 3PS, United Kingdom; Department of Genetics, Evolution and Environment, University College, London, London, WC1E 6BT, United Kingdom.
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23
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Kawagoshi T, Uno Y, Nishida C, Matsuda Y. The Staurotypus turtles and aves share the same origin of sex chromosomes but evolved different types of heterogametic sex determination. PLoS One 2014; 9:e105315. [PMID: 25121779 PMCID: PMC4133349 DOI: 10.1371/journal.pone.0105315] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/18/2014] [Indexed: 12/24/2022] Open
Abstract
Reptiles have a wide diversity of sex-determining mechanisms and types of sex chromosomes. Turtles exhibit temperature-dependent sex determination and genotypic sex determination, with male heterogametic (XX/XY) and female heterogametic (ZZ/ZW) sex chromosomes. Identification of sex chromosomes in many turtle species and their comparative genomic analysis are of great significance to understand the evolutionary processes of sex determination and sex chromosome differentiation in Testudines. The Mexican giant musk turtle (Staurotypus triporcatus, Kinosternidae, Testudines) and the giant musk turtle (Staurotypus salvinii) have heteromorphic XY sex chromosomes with a low degree of morphological differentiation; however, their origin and linkage group are still unknown. Cross-species chromosome painting with chromosome-specific DNA from Chinese soft-shelled turtle (Pelodiscus sinensis) revealed that the X and Y chromosomes of S. triporcatus have homology with P. sinensis chromosome 6, which corresponds to the chicken Z chromosome. We cloned cDNA fragments of S. triporcatus homologs of 16 chicken Z-linked genes and mapped them to S. triporcatus and S. salvinii chromosomes using fluorescence in situ hybridization. Sixteen genes were localized to the X and Y long arms in the same order in both species. The orders were also almost the same as those of the ostrich (Struthio camelus) Z chromosome, which retains the primitive state of the avian ancestral Z chromosome. These results strongly suggest that the X and Y chromosomes of Staurotypus turtles are at a very early stage of sex chromosome differentiation, and that these chromosomes and the avian ZW chromosomes share the same origin. Nonetheless, the turtles and birds acquired different systems of heterogametic sex determination during their evolution.
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Affiliation(s)
- Taiki Kawagoshi
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoshinobu Uno
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Chizuko Nishida
- Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Yoichi Matsuda
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- * E-mail:
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24
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Yazdi HP, Ellegren H. Old but Not (So) Degenerated—Slow Evolution of Largely Homomorphic Sex Chromosomes in Ratites. Mol Biol Evol 2014; 31:1444-1453. [DOI: 10.1093/molbev/msu101] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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25
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Ishijima J, Uno Y, Nishida C, Matsuda Y. Genomic structures of the kW1 loci on the Z and W chromosomes in ratite birds: structural changes at an early stage of W chromosome differentiation. Cytogenet Genome Res 2014; 142:255-67. [PMID: 24820528 DOI: 10.1159/000362479] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2014] [Indexed: 11/19/2022] Open
Abstract
The W chromosome of ratite birds shows minimal morphological differentiation and retains homology of genetic linkage and gene order with a substantial stretch of the Z chromosome; however, the molecular structure in the differentiated region is still not well known. The kW1 sequence was isolated from the kiwi as a W-specific DNA marker for PCR-based molecular sexing of ratite birds. In ratite W chromosomes, this sequence commonly contains a ∼200-bp deletion. To characterize the very early event of avian sex chromosome differentiation, we performed molecular cytogenetic analyses of kW1 and its flanking sequences in paleognathous and neognathous birds and reptiles. Female-specific repeats were found in the kW1-flanking sequence of the cassowary (Casuarius casuarius), and the repeats have been amplified in the pericentromeric region of the W chromosomes of ratites, which may have resulted from the cessation of meiotic recombination between the Z and W chromosomes at an early stage of sex chromosome differentiation. The presence of the kW1 sequence in neognathous birds and a crocodilian species suggests that the kW1 sequence was present in the ancestral genome of Archosauria; however, it disappeared in other reptilian taxa and several lineages of neognathous birds.
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Affiliation(s)
- Junko Ishijima
- Laboratory of Animal Cytogenetics, Department of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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26
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27
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Comparison of the Chromosome Structures between the Chicken and Three Anserid Species, the Domestic Duck ( Anas platyrhynchos), Muscovy Duck ( Cairina moschata), and Chinese Goose ( Anser cygnoides), and the Delineation of their Karyotype Evolution by Comparative Chromosome Mapping. J Poult Sci 2014. [DOI: 10.2141/jpsa.0130090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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28
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Bewick AJ, Chain FJJ, Zimmerman LB, Sesay A, Gilchrist MJ, Owens NDL, Seifertova E, Krylov V, Macha J, Tlapakova T, Kubickova S, Cernohorska H, Zarsky V, Evans BJ. A large pseudoautosomal region on the sex chromosomes of the frog Silurana tropicalis. Genome Biol Evol 2013; 5:1087-98. [PMID: 23666865 PMCID: PMC3698919 DOI: 10.1093/gbe/evt073] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sex chromosome divergence has been documented across phylogenetically diverse species, with amphibians typically having cytologically nondiverged (“homomorphic”) sex chromosomes. With an aim of further characterizing sex chromosome divergence of an amphibian, we used “RAD-tags” and Sanger sequencing to examine sex specificity and heterozygosity in the Western clawed frog Silurana tropicalis (also known as Xenopus tropicalis). Our findings based on approximately 20 million genotype calls and approximately 200 polymerase chain reaction-amplified regions across multiple male and female genomes failed to identify a substantially sized genomic region with genotypic hallmarks of sex chromosome divergence, including in regions known to be tightly linked to the sex-determining region. We also found that expression and molecular evolution of genes linked to the sex-determining region did not differ substantially from genes in other parts of the genome. This suggests that the pseudoautosomal region, where recombination occurs, comprises a large portion of the sex chromosomes of S. tropicalis. These results may in part explain why African clawed frogs have such a high incidence of polyploidization, shed light on why amphibians have a high rate of sex chromosome turnover, and raise questions about why homomorphic sex chromosomes are so prevalent in amphibians.
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Affiliation(s)
- Adam J Bewick
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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29
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Uebbing S, Künstner A, Mäkinen H, Ellegren H. Transcriptome sequencing reveals the character of incomplete dosage compensation across multiple tissues in flycatchers. Genome Biol Evol 2013; 5:1555-66. [PMID: 23925789 PMCID: PMC3762201 DOI: 10.1093/gbe/evt114] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sex chromosome divergence, which follows the cessation of recombination and degeneration of the sex-limited chromosome, can cause a reduction in expression level for sex-linked genes in the heterozygous sex, unless some mechanisms of dosage compensation develops to counter the reduction in gene dose. Because large-scale perturbations in expression levels arising from changes in gene dose might have strong deleterious effects, the evolutionary response should be strong. However, in birds and in at least some other female heterogametic organisms, wholesale sex chromosome dosage compensation does not seem to occur. Using RNA-seq of multiple tissues and individuals, we investigated male and female expression levels of Z-linked and autosomal genes in the collared flycatcher, a bird for which a draft genome sequence recently has been reported. We found that male expression of Z-linked genes was on average 50% higher than female expression, although there was considerable variation in the male-to-female ratio among genes. The ratio for individual genes was well correlated among tissues and there was also a correlation in the extent of compensation between flycatcher and chicken orthologs. The relative excess of male expression was positively correlated with expression breadth, expression level, and number of interacting proteins (protein connectivity), and negatively correlated with variance in expression. These observations lead to a model of compensation occurring on a gene-by-gene basis, supported by an absence of clustering of genes on the Z chromosome with respect to the extent of compensation. Equal mean expression level of autosomal and Z-linked genes in males, and 50% higher expression of autosomal than Z-linked genes in females, is compatible with that partial compensation is achieved by hypertranscription from females' single Z chromosome. A comparison with male-to-female expression ratios in orthologous Z-linked genes of ostriches, where Z-W recombination still occurs, suggests that male-biased expression of Z-linked genes is a derived trait after avian sex chromosome divergence.
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Affiliation(s)
- Severin Uebbing
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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30
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Adolfsson S, Ellegren H. Lack of dosage compensation accompanies the arrested stage of sex chromosome evolution in ostriches. Mol Biol Evol 2013; 30:806-10. [PMID: 23329687 PMCID: PMC3603317 DOI: 10.1093/molbev/mst009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sex chromosome evolution is usually seen as a process that, once initiated, will inevitably progress toward an advanced stage of degeneration of the nonrecombining chromosome. However, despite evidence that avian sex chromosome evolution was initiated >100 Ma, ratite birds have been trapped in an arrested stage of sex chromosome divergence. We performed RNA sequencing of several tissues from male and female ostriches and assembled the transcriptome de novo. A total of 315 Z-linked genes fell into two categories: those that have equal expression level in the two sexes (for which Z–W recombination still occurs) and those that have a 2-fold excess of male expression (for which Z–W recombination has ceased). We suggest that failure to evolve dosage compensation has constrained sex chromosome divergence in this basal avian lineage. Our results indicate that dosage compensation is a prerequisite for, not only a consequence of, sex chromosome evolution.
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Affiliation(s)
- Sofia Adolfsson
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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31
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Miura I, Ohtani H, Ogata M. Independent degeneration of W and Y sex chromosomes in frog Rana rugosa. Chromosome Res 2012; 20:47-55. [PMID: 22143254 DOI: 10.1007/s10577-011-9258-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
The frog Rana rugosa uniquely possesses two different sex-determining systems of XX/XY and ZZ/ZW, separately in the geographic populations. The sex chromosomes of both types share the same origin at chromosome 7, and the structural differences between X and Y or Z and W were evolved through two inversions. In order to ascertain the mechanisms of degeneration of W and Y chromosomes, we gynogenetically produced homozygous diploids WW and YY and examined their viability. Tadpoles from geographic group N (W(N)W(N)) containing three populations died of edema at an early developmental stage within 10 days after hatching, while tadpoles from the geographic group K (W(K)W(K)) that contained two populations died of underdeveloped growth at a much later stage, 40-50 days after fertilization. On the contrary, W(N)W(K) and W(K)W(N) hybrid embryos were viable, successfully passed the two lethal stages, and survived till the attainment of adulthood. The observed survival implies that the lethal genes of the W chromosomes are not shared by the two groups and thus demonstrates their independent degeneration histories between the local groups. In sharp contrast, a sex-linked gene of androgen receptor gene (AR) from the W chromosome was down-regulated in expression in both the groups, suggesting that inactivation of the W-AR allele preceded divergence of the two groups and appearance of the lethal genes. Besides, the YY embryos died of cardiac edema immediately after hatching. The symptom of lethality and the stage of developmental arrest differed from those for either of WW lethal embryos. We therefore conclude that the W and Y chromosomes involve no evolutionary common scenario for degeneration.
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Affiliation(s)
- Ikuo Miura
- Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Japan.
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32
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Gschwend AR, Weingartner LA, Moore RC, Ming R. The sex-specific region of sex chromosomes in animals and plants. Chromosome Res 2012; 20:57-69. [PMID: 22105696 DOI: 10.1007/s10577-011-9255-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Our understanding of the evolution of sex chromosomes has increased greatly in recent years due to a number of molecular evolutionary investigations in divergent sex chromosome systems, and these findings are reshaping theories of sex chromosome evolution. In particular, the dynamics of the sex-determining region (SDR) have been demonstrated by recent findings in ancient and incipient sex chromosomes. Radical changes in genomic structure and gene content in the male specific region of the Y chromosome between human and chimpanzee indicated rapid evolution in the past 6 million years, defying the notion that the pace of evolution in the SDR was fast at early stages but slowed down overtime. The chicken Z and the human X chromosomes appeared to have acquired testis-expressed genes and expanded in intergenic regions. Transposable elements greatly contributed to SDR expansion and aided the trafficking of genes in the SDR and its X or Z counterpart through retrotransposition. Dosage compensation is not a destined consequence of sex chromosomes as once thought. Most X-linked microRNA genes escape silencing and are expressed in testis. Collectively, these findings are challenging many of our preconceived ideas of the evolutionary trajectory and fates of sex chromosomes.
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Affiliation(s)
- Andrea R Gschwend
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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33
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Abstract
Although sex chromosomes have been the focus of a great deal of scientific scrutiny, most interest has centred on understanding the evolution and relative importance of X and Z chromosomes. By contrast, the sex-limited W and Y chromosomes have received far less attention, both because of their generally degenerate nature and the difficulty in studying non-recombining and often highly heterochromatic genomic regions. However, recent theory and empirical evidence suggest that the W and Y chromosomes play a far more important role in sex-specific fitness traits than would be expected based on their size alone, and this importance may explain the persistence of some Y and W chromosomes in the face of powerful degradative forces. In addition to their role in fertility and fecundity, the sex-limited nature of these genomic regions results in unique evolutionary forces acting on Y and W chromosomes, implicating them as potentially major contributors to sexual selection and speciation. Recent empirical studies have borne out these predictions and revealed that some W and Y chromosomes play a vital role in key sex-specific evolutionary processes.
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Affiliation(s)
- Judith E Mank
- Department of Zoology, Edward Grey Institute, University of Oxford, South Parks Road, Oxford, UK.
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34
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Pokorná M, Kratochvíl L, Kejnovský E. Microsatellite distribution on sex chromosomes at different stages of heteromorphism and heterochromatinization in two lizard species (Squamata: Eublepharidae: Coleonyx elegans and lacertidae: Eremias velox). BMC Genet 2011; 12:90. [PMID: 22013909 PMCID: PMC3215666 DOI: 10.1186/1471-2156-12-90] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 10/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The accumulation of repetitive sequences such as microsatellites during the differentiation of sex chromosomes has not been studied in most squamate reptiles (lizards, amphisbaenians and snakes), a group which has a large diversity of sex determining systems. It is known that the Bkm repeats containing tandem arrays of GATA tetranucleotides are highly accumulated on the degenerated W chromosomes in advanced snakes. Similar, potentially homologous, repetitive sequences were found on sex chromosomes in other vertebrates. Using FISH with probes containing all possible mono-, di-, and tri-nucleotide sequences and GATA, we studied the genome distribution of microsatellite repeats on sex chromosomes in two lizard species (the gecko Coleonyx elegans and the lacertid Eremias velox) with independently evolved sex chromosomes. The gecko possesses heteromorphic euchromatic sex chromosomes, while sex chromosomes in the lacertid are homomorphic and the W chromosome is highly heterochromatic. Our aim was to test whether microsatellite distribution on sex chromosomes corresponds to the stage of their heteromorphism or heterochromatinization. Moreover, because the lizards lie phylogenetically between snakes and other vertebrates with the Bkm-related repeats on sex chromosomes, the knowledge of their repetitive sequence is informative for the determination of conserved versus convergently evolved repetitive sequences across vertebrate lineages. RESULTS Heteromorphic sex chromosomes of C. elegans do not show any sign of microsatellite accumulation. On the other hand, in E. velox, certain microsatellite sequences are extensively accumulated over the whole length or parts of the W chromosome, while others, including GATA, are absent on this heterochromatinized sex chromosome. CONCLUSION The accumulation of microsatellite repeats corresponds to the stage of heterochromatinization of sex chromosomes rather than to their heteromorphism. The lack of GATA repeats on the sex chromosomes of both lizards suggests that the Bkm-related repeats on sex chromosomes in snakes and other vertebrates evolved convergently. The comparison of microsatellite sequences accumulated on sex chromosomes in E. velox and in other eukaryotic organisms suggests that historical contingency, not characteristics of particular sequences, plays a major role in the determination of which microsatellite sequence is accumulated on the sex chromosomes in a particular lineage.
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Affiliation(s)
- Martina Pokorná
- Department of Ecology, Charles University in Prague, Viničná 7, 128 44 Praha 2, Czech Republic
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35
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Jordan CY, Charlesworth D. The potential for sexually antagonistic polymorphism in different genome regions. Evolution 2011; 66:505-16. [PMID: 22276544 DOI: 10.1111/j.1558-5646.2011.01448.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sex differences in the fitness effects of alleles at a single locus (intralocus sexual antagonism, or SA) have several evolutionary consequences. Among the consequences of SA, polymorphisms at genes partially linked to the sex-determining region of the sex chromosome pair potentially drive the evolution of suppressed recombination between the sex chromosomes. Understanding the conditions under which SA polymorphism can exist at such pseudo-autosomal (or PAR) loci should increase understanding of the evolution of recombination between sex chromosome pairs, and can help predict when we may expect potentially empirically detectable allele frequency differences between the sexes. Models so far published have concluded that PAR genes can maintain SA polymorphisms over a wider range of selection coefficients than autosomal ones, but have used restrictive assumptions. We expand the modeling of SA alleles at a single locus with the full range of degrees of linkage to the male-specific region, to include strong or weak selection and the possibility of different dominance coefficients in the two sexes. We confirm the previous major conclusion that SA polymorphisms are generally maintained in a larger region of parameter space if the locus is in the PAR than if it is autosomal.
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Affiliation(s)
- Crispin Y Jordan
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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36
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Suh A, Kriegs JO, Brosius J, Schmitz J. Retroposon Insertions and the Chronology of Avian Sex Chromosome Evolution. Mol Biol Evol 2011; 28:2993-7. [PMID: 21633113 DOI: 10.1093/molbev/msr147] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Alexander Suh
- Institute of Experimental Pathology, University of Münster, Münster, Germany.
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37
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Pigozzi MI. Diverse stages of sex-chromosome differentiation in tinamid birds: evidence from crossover analysis in Eudromia elegans and Crypturellus tataupa. Genetica 2011; 139:771-7. [PMID: 21567220 DOI: 10.1007/s10709-011-9581-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Accepted: 04/30/2011] [Indexed: 01/10/2023]
Abstract
All extant birds share the same sex-chromosome system: ZZ males and ZW females with striking differences in the stages of sex-chromosome differentiation between the primitive palaeognathus ratites and the large majority of avian species grouped within neognaths. Evolutionarily close to ratites is the neotropical order Tinamiformes that has been scarcely explored regarding their ZW pair morphology and constitution. Tinamous, when compared to ratites, constitute a large group among Palaeognathae, therefore, exploring the extent of homology between the Z and W chromosomes in this group might reveal key features on the evolution of the avian sex chromosomes. We mapped MLH1 foci that are crossover markers on pachytene bivalents to determine the size and localization of the homologous region shared by the Z and W chromosomes in two tinamous: Eudromia elegans and Crypturellus tataupa. We found that the homologous (pseudoautosomal) region differ significantly in size between these two species. They both have a single recombination event on the long arm of the acrocentric Z and W chromosomes. However, in E. elegans the pseudoautosomal region occupies one-fourth of the W chromosome, while in C. tataupa it is restricted to the tip of the long arm of the W. The W chromosomes in these two species differ in their heterochromatin content: in E. elegans it shows a terminal euchromatic segment and in C. tataupa is completely heterochromatic. These results show that tinamous have ZW pairs with more diversified stages of differentiation compared to ratites. Finally, the idea that the avian proto-sex chromosomes started to diverge from the end of the long arm towards the centromere of an acrocentric pair is discussed.
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Affiliation(s)
- María Inés Pigozzi
- Facultad de Medicina, Instituto de Investigaciones en Reproducción, Paraguay 2155 piso 10, C1121ABG Buenos Aires, Argentina.
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Nascimento J, Quinderé YRSD, Recco-Pimentel SM, Lima JRF, Lourenço LB. Heteromorphic Z and W sex chromosomes in Physalaemus ephippifer (Steindachner, 1864) (Anura, Leiuperidae). Genetica 2010; 138:1127-32. [DOI: 10.1007/s10709-010-9501-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 09/13/2010] [Indexed: 11/30/2022]
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39
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Pokorná M, Rábová M, Ráb P, Ferguson-Smith MA, Rens W, Kratochvíl L. Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination. Chromosome Res 2010; 18:809-20. [DOI: 10.1007/s10577-010-9154-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 08/09/2010] [Accepted: 08/11/2010] [Indexed: 10/19/2022]
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40
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Charlesworth D, Mank JE. The birds and the bees and the flowers and the trees: lessons from genetic mapping of sex determination in plants and animals. Genetics 2010; 186:9-31. [PMID: 20855574 PMCID: PMC2940314 DOI: 10.1534/genetics.110.117697] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.
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Affiliation(s)
- Deborah Charlesworth
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom.
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41
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Non-homologous sex chromosomes of birds and snakes share repetitive sequences. Chromosome Res 2010; 18:787-800. [DOI: 10.1007/s10577-010-9152-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/04/2010] [Accepted: 08/04/2010] [Indexed: 11/26/2022]
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Abstract
The mosquito Anopheles gambiae has heteromorphic sex chromosomes, while the mosquito Aedes aegypti has homomorphic sex chromosomes. We use retrotransposed gene duplicates to show an excess of movement off the An. gambiae X chromosome only after the split with Ae. aegypti, suggesting that their ancestor had homomorphic sex chromosomes.
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43
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Abstract
Sex chromosomes have evolved multiple times in many taxa. The recent explosion in the availability of whole genome sequences from a variety of organisms makes it possible to investigate sex chromosome evolution within and across genomes. Comparative genomic studies have shown that quite distant species may share fundamental properties of sex chromosome evolution, while very similar species can evolve unique sex chromosome systems. Furthermore, within-species genomic analyses can illuminate chromosome-wide sequence and expression polymorphisms. Here, we explore recent advances in the study of vertebrate sex chromosomes achieved using genomic analyses.
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Affiliation(s)
- Melissa A Wilson
- Center for Comparative Genomics and Bioinformatics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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44
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The role of repetitive DNA in structure and evolution of sex chromosomes in plants. Heredity (Edinb) 2009; 102:533-41. [PMID: 19277056 DOI: 10.1038/hdy.2009.17] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic genomes contain a large proportion of repetitive DNA sequences, mostly transposable elements (TEs) and tandem repeats. These repetitive sequences often colonize specific chromosomal (Y or W chromosomes, B chromosomes) or subchromosomal (telomeres, centromeres) niches. Sex chromosomes, especially non-recombining regions of the Y chromosome, are subject to different evolutionary forces compared with autosomes. In non-recombining regions of the Y chromosome repetitive DNA sequences are accumulated, representing a dominant and early process forming the Y chromosome, probably before genes start to degenerate. Here we review the occurrence and role of repetitive DNA in Y chromosome evolution in various species with a focus on dioecious plants. We also discuss the potential link between recombination and transposition in shaping genomes.
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45
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Itoh Y, Kampf K, Arnold AP. Disruption of FEM1C-W gene in zebra finch: evolutionary insights on avian ZW genes. Chromosoma 2009; 118:323-34. [PMID: 19139913 DOI: 10.1007/s00412-008-0199-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 12/08/2008] [Accepted: 12/09/2008] [Indexed: 01/16/2023]
Abstract
Sex chromosome genes control sex determination and differentiation, but the mechanisms of sex determination in birds are unknown. In this study, we analyzed the gene FEM1C which is highly conserved from Caenorhabditis elegans to higher vertebrates and interacts with the sex determining pathway in C. elegans. We found that FEM1C is located on the Z and W chromosome of zebra finches and probably other Passerine birds, but shows only Z linkage in other avian orders. In the zebra finch, FEM1C-W is degraded because of a point mutation and possibly because of loss of the first exon containing the start methionine. Thus, FEM1C-W appears to have degenerated or been lost from most bird species. FEM1C-Z is expressed in a cytoplasmic location in zebra finch fibroblast cells, as in C. elegans. FEM1C represents an interesting example of evolutionary degradation of a W chromosome gene.
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Affiliation(s)
- Yuichiro Itoh
- Department of Physiological Science, University of California, UCLA 621 Charles E. Young Drive South, Room 4117, Los Angeles, CA 90095-1606, USA.
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46
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Arnold AP, Itoh Y, Melamed E. A bird's-eye view of sex chromosome dosage compensation. Annu Rev Genomics Hum Genet 2008; 9:109-27. [PMID: 18489256 DOI: 10.1146/annurev.genom.9.081307.164220] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intensive study of a few genetically tractable species with XX/XY sex chromosomes has produced generalizations about the process of sex chromosome dosage compensation that do not fare well when applied to ZZ/ZW sex chromosome systems, such as those in birds. The inherent sexual imbalance in dose of sex chromosome genes has led to the evolution of sex-chromosome-wide mechanisms for balancing gene dosage between the sexes and relative to autosomal genes. Recent advances in our knowledge of avian genomes have led to a reexamination of sex-specific dosage compensation (SSDC) in birds, which is less effective than in known XX/XY systems. Insights about the mechanisms of SSDC in birds also suggest similarities to and differences from those in XX/XY species. Birds are thus offering new opportunities for studying dosage compensation in a ZZ/ZW system, which should shed light on the evolution of SSDC more broadly.
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Affiliation(s)
- Arthur P Arnold
- Department of Physiological Science and Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California 90095, USA.
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47
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Molecular structures of centromeric heterochromatin and karyotypic evolution in the Siamese crocodile (Crocodylus siamensis) (Crocodylidae, Crocodylia). Chromosome Res 2008; 16:1119-32. [DOI: 10.1007/s10577-008-1263-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/20/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
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48
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Janes DE, Ezaz T, Marshall Graves JA, Edwards SV. Recombination and nucleotide diversity in the sex chromosomal pseudoautosomal region of the emu, Dromaius novaehollandiae. J Hered 2008; 100:125-36. [PMID: 18775880 DOI: 10.1093/jhered/esn065] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pseudoautosomal regions (PARs) shared by avian Z and W sex chromosomes are typically small homologous regions within which recombination still occurs and are hypothesized to share the properties of autosomes. We capitalized on the unusual structure of the sex chromosomes of emus, Dromaius novaehollandiae, which consist almost entirely of PAR shared by both sex chromosomes, to test this hypothesis. We compared recombination, linkage disequilibrium (LD), GC content, and nucleotide diversity between pseudoautosomal and autosomal loci derived from 11 emu bacterial artificial chromosome (BAC) clones that were mapped to chromosomes by fluorescent in situ hybridization. Nucleotide diversity (pi = 4N(e)mu) was not significantly lower in pseudoautosomal loci (14 loci, 1.9 +/- 2.4 x 10(-3)) than autosomal loci (8 loci, 4.2 +/- 6.1 x 10(-3)). By contrast, recombination per site within BAC-end sequences (rho = 4Nc) (pseudoautosomal, 3.9 +/- 6.9 x 10(-2); autosomal, 2.3 +/- 3.7 x 10(-2)) was higher and average LD (D') (pseudoautosomal, 4.2 +/- 0.2 x 10(-1); autosomal, 4.7 +/- 0.5 x 10(-1)) slightly lower in pseudoautosomal sequences. We also report evidence of deviation from a simple neutral model in the PAR and in autosomal loci, possibly caused by departures from demographic equilibrium, such as population growth. This study provides a snapshot of the population genetics of avian sex chromosomes at an early stage of differentiation.
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Affiliation(s)
- Daniel E Janes
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
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49
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The ZW sex chromosomes of Gekko hokouensis (Gekkonidae, Squamata) represent highly conserved homology with those of avian species. Chromosoma 2008; 118:43-51. [DOI: 10.1007/s00412-008-0176-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 06/11/2008] [Accepted: 07/16/2008] [Indexed: 12/31/2022]
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50
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Comparative chromosome mapping of sex-linked genes and identification of sex chromosomal rearrangements in the Japanese wrinkled frog (Rana rugosa, Ranidae) with ZW and XY sex chromosome systems. Chromosome Res 2008; 16:637-47. [DOI: 10.1007/s10577-008-1217-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 02/25/2008] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
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