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Behrens KA, Zimmermann H, Blažek R, Reichard M, Koblmüller S, Kocher TD. Turnover of sex chromosomes in the Lake Tanganyika cichlid tribe Tropheini (Teleostei: Cichlidae). Sci Rep 2024; 14:2471. [PMID: 38291228 PMCID: PMC10828463 DOI: 10.1038/s41598-024-53021-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 01/25/2024] [Indexed: 02/01/2024] Open
Abstract
Sex chromosome replacement is frequent in many vertebrate clades, including fish, frogs, and lizards. In order to understand the mechanisms responsible for sex chromosome turnover and the early stages of sex chromosome divergence, it is necessary to study lineages with recently evolved sex chromosomes. Here we examine sex chromosome evolution in a group of African cichlid fishes (tribe Tropheini) which began to diverge from one another less than 4 MYA. We have evidence for a previously unknown sex chromosome system, and preliminary indications of several additional systems not previously reported in this group. We find a high frequency of sex chromosome turnover and estimate a minimum of 14 turnovers in this tribe. We date the origin of the most common sex determining system in this tribe (XY-LG5/19) near the base of one of two major sub-clades of this tribe, about 3.4 MY ago. Finally, we observe variation in the size of one sex-determining region that suggests independent evolution of evolutionary strata in species with a shared sex-determination system. Our results illuminate the rapid rate of sex chromosome turnover in the tribe Tropheini and set the stage for further studies of the dynamics of sex chromosome evolution in this group.
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Affiliation(s)
- Kristen A Behrens
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Holger Zimmermann
- Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, 603 00, Brno, Czech Republic
- Institute of Biology, University of Graz, Universitätsplatz 2, 8010, Graz, Austria
| | - Radim Blažek
- Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, 603 00, Brno, Czech Republic
| | - Martin Reichard
- Institute of Vertebrate Biology, Czech Academy of Sciences, Květná 8, 603 00, Brno, Czech Republic
- Department of Ecology and Vertebrate Zoology, University of Łódź, Łódź, Poland
| | - Stephan Koblmüller
- Institute of Biology, University of Graz, Universitätsplatz 2, 8010, Graz, Austria
| | - Thomas D Kocher
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
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Hu N, Sanderson BJ, Guo M, Feng G, Gambhir D, Hale H, Wang D, Hyden B, Liu J, Smart LB, DiFazio SP, Ma T, Olson MS. Evolution of a ZW sex chromosome system in willows. Nat Commun 2023; 14:7144. [PMID: 37932261 PMCID: PMC10628195 DOI: 10.1038/s41467-023-42880-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 10/24/2023] [Indexed: 11/08/2023] Open
Abstract
Transitions in the heterogamety of sex chromosomes (e.g., XY to ZW or vice versa) fundamentally alter the genetic basis of sex determination, however the details of these changes have been studied in only a few cases. In an XY to ZW transition, the X is likely to give rise to the W because they both carry feminizing genes and the X is expected to harbour less genetic load than the Y. Here, using a new reference genome for Salix exigua, we trace the X, Y, Z, and W sex determination regions during the homologous transition from an XY system to a ZW system in willow (Salix). We show that both the W and the Z arose from the Y chromosome. We find that the new Z chromosome shares multiple homologous putative masculinizing factors with the ancestral Y, whereas the new W lost these masculinizing factors and gained feminizing factors. The origination of both the W and Z from the Y was permitted by an unexpectedly low genetic load on the Y and this indicates that the origins of sex chromosomes during homologous transitions may be more flexible than previously considered.
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Affiliation(s)
- Nan Hu
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Brian J Sanderson
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
| | - Minghao Guo
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Guanqiao Feng
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Diksha Gambhir
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Haley Hale
- HudsonAlpha Institute for Biotechnology, 601 Genome Way, Huntsville, AL, USA
| | - Deyan Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Brennan Hyden
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Stephen P DiFazio
- Department of Biology, West Virginia University, Morgantown, WV, USA
| | - Tao Ma
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Matthew S Olson
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
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Curzon AY, Shirak A, Ron M, Seroussi E. Master-Key Regulators of Sex Determination in Fish and Other Vertebrates-A Review. Int J Mol Sci 2023; 24. [PMID: 36768795 DOI: 10.3390/ijms24032468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/12/2023] [Accepted: 01/25/2023] [Indexed: 02/01/2023] Open
Abstract
In vertebrates, mainly single genes with an allele ratio of 1:1 trigger sex-determination (SD), leading to initial equal sex-ratios. Such genes are designated master-key regulators (MKRs) and are frequently associated with DNA structural variations, such as copy-number variation and null-alleles. Most MKR knowledge comes from fish, especially cichlids, which serve as a genetic model for SD. We list 14 MKRs, of which dmrt1 has been identified in taxonomically distant species such as birds and fish. The identification of MKRs with known involvement in SD, such as amh and fshr, indicates that a common network drives SD. We illustrate a network that affects estrogen/androgen equilibrium, suggesting that structural variation may exert over-expression of the gene and thus form an MKR. However, the reason why certain factors constitute MKRs, whereas others do not is unclear. The limited number of conserved MKRs suggests that their heterologous sequences could be used as targets in future searches for MKRs of additional species. Sex-specific mortality, sex reversal, the role of temperature in SD, and multigenic SD are examined, claiming that these phenomena are often consequences of artificial hybridization. We discuss the essentiality of taxonomic authentication of species to validate purebred origin before MKR searches.
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Behrens KA, Koblmüller S, Kocher TD. Sex chromosomes in the tribe Cyprichromini (Teleostei: Cichlidae) of Lake Tanganyika. Sci Rep 2022; 12:17998. [PMID: 36289404 DOI: 10.1038/s41598-022-23017-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 10/21/2022] [Indexed: 01/24/2023] Open
Abstract
Sex determining loci have been described on at least 12 of 22 chromosomes in East African cichlid fishes, indicating a high rate of sex chromosome turnover. To better understand the rates and patterns of sex chromosome replacement, we used new methods to characterize the sex chromosomes of the cichlid tribe Cyprichromini from Lake Tanganyika. Our k-mer based methods successfully identified sex-linked polymorphisms without the need for a reference genome. We confirm the three previously reported sex chromosomes in this group. We determined the polarity of the sex chromosome turnover on LG05 in Cyprichromis as ZW to XY. We identified a new ZW locus on LG04 in Paracyprichromis brieni. The LG15 XY locus in Paracyprichromis nigripinnis was not found in other Paracyprichromis species, and the sample of Paracyprichromis sp. "tembwe" is likely to be of hybrid origin. Although highly divergent sex chromosomes are thought to develop in a stepwise manner, we show two cases (LG05-ZW and LG05-XY) in which the region of differentiation encompasses most of the chromosome, but appears to have arisen in a single step. This study expands our understanding of sex chromosome evolution in the Cyprichromini, and indicates an even higher level of sex chromosome turnover than previously thought.
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