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Title: Genomic characterization of sex‐identification markers in Sebastes carnatus and Sebastes chrysomelas rockfishes

Fish have evolved a variety of sex‐determining (SD) systems including male heterogamy (XY), female heterogamy (ZW) and environmental SD. Little is known about SD mechanisms ofSebastesrockfishes, a highly speciose genus of importance to evolutionary and conservation biology. Here, we characterize the sex determination system in the sympatrically distributed sister speciesSebastes chrysomelasandSebastes carnatus. To identify sex‐specific genotypic markers, double digest restriction site – associated DNA sequencing (ddRAD‐seq) of genomic DNA from 40 sexed individuals of both species was performed. Loci were filtered for presence in all of the individuals of one sex, absence in the other sex and no heterozygosity. Of the 74 965 loci present in all males, 33 male‐specific loci met the criteria in at least one species and 17 in both. Conversely, no female‐specific loci were detected, together providing evidence of an XY sex determination system in both species. When aligned to a draft reference genome fromSebastes aleutianus, 26 sex‐specific loci were interspersed among 1168 loci that were identical between sexes. The nascent Y chromosome averaged 5% divergence from the X chromosome and mapped to referenceSebastesgenome scaffolds totalling 6.9Mbp in length. These scaffolds aligned to a single chromosome in three model fish genomes. Read coverage differences were also detected between sex‐specific and autosomal loci. A PCR‐RFLP assay validated the bioinformatic results and correctly identified sex of five additional individuals of known sex. A sex‐determining gene in other teleostsgonadal soma‐derived factor(gsdf) was present in the model fish chromosomes that spanned our sex‐specific markers.

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Author(s) / Creator(s):
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Date Published:
Journal Name:
Molecular Ecology
Page Range / eLocation ID:
p. 2165-2175
Medium: X
Sponsoring Org:
National Science Foundation
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