MEPS 627:195-200 (2019)  -  DOI: https://doi.org/10.3354/meps13082

ABSTRACT: Sex-specific genetic markers, markers found in one sex but not the other, can be used to recognize a species’ sex chromosome system in cases where traditional karyotyping fails. Species with male-specific markers have an XX/XY system, while species with female-specific markers have a ZZ/ZW system. Here, we used data from restriction site-associated DNA sequencing, or RADseq, from 2 species of combtooth blenny, Istiblennius lineatus and I. steindachneri, to identify an excess of female-specific genetic markers, which points to ZZ/ZW sex chromosomes. We used PCR to validate the sex-specificity of one of these female-specific restriction site-associated DNA markers in an additional Istiblennius species, I. edentulus. We observed no sex-specific PCR amplification in 2 other Istiblennius species and 2 Blenniella species. This Istiblennius ZZ/ZW system, when combined with cytogenetic data from the literature illustrating an XX/XY system in Parablennius, establishes a transition between sex chromosome systems within Blenniidae.

KEY WORDS: Blenny · Fish · RADseq · Endocrine disrupting chemicals · Biomonitoring