Variations on a theme: Genomics of sex determination in the cichlid fish Astatotilapia burtoniReport as inadecuate

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BMC Genomics

, 17:883

Comparative and evolutionary genomics


BackgroundSex chromosomes change more frequently in fish than in mammals or birds. However, certain chromosomes or genes are repeatedly used as sex determinants in different members of the teleostean lineage. East African cichlids are an enigmatic model system in evolutionary biology representing some of the most diverse extant vertebrate adaptive radiations. How sex is determined and if different sex-determining mechanisms contribute to speciation is unknown for almost all of the over 1,500 cichlid species of the Great Lakes. Here, we investigated the genetic basis of sex determination in a cichlid from Lake Tanganyika, Astatotilapia burtoni, a member of the most species-rich cichlid lineage, the haplochromines.

ResultsWe used RAD-sequencing of crosses for two populations of A. burtoni, a lab strain and fish caught at the south of Lake Tanganyika. Using association mapping and comparative genomics, we confirmed male heterogamety in A. burtoni and identified different sex chromosomes LG5 and LG18 in the two populations of the same species. LG5, the sex chromosome of the lab strain, is a fusion chromosome in A. burtoni. Wnt4 is located on this chromosome, representing the best candidate identified so far for the master sex-determining gene in our lab strain of A. burtoni.

ConclusionsCichlids exemplify the high turnover rate of sex chromosomes in fish with two different chromosomes, LG5 and LG18, containing major sex-determining loci in the two populations of A. burtoni examined here. However, they also illustrate that particular chromosomes are more likely to be used as sex chromosomes. Chromosome 5 is such a chromosome, which has evolved several times as a sex chromosome, both in haplochromine cichlids from all Great Lakes and also in other teleost fishes.

KeywordsSex determination Cichlid Wnt4 Sex chromosome RAD sequencing AbbreviationsESDEnvironmental sex determination

GOGene ontology

GSDGenetic sex determination

kbKilo bases

kmKilo meters

LGLinkage group

LMLake Malawi

LTLake Tanganyika

LVLake Victoria

MBMega bases

myMillion years

OBOrange blotch

RAD sequencingRestriction site associated DNA sequencing

SDSex determination

SNPSingle nucleotide polymorphism

Electronic supplementary materialThe online version of this article doi:10.1186-s12864-016-3178-0 contains supplementary material, which is available to authorized users.

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Author: Astrid Böhne - Catherine A. Wilson - John H. Postlethwait - Walter Salzburger


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