Turnover of multiple sex chromosomes in catfish (Siluriformes, Loricariidae): a glimpse from whole chromosome painting.

The remarkable fish biodiversity encompasses also great sex chromosome variability. catfish belong to Neotropical models for karyotype and sex chromosome research. Some species possess one of the three male-heterogametic sex chromosome systems, XY, XXY or XYY, while other members of the genus have yet uncharacterized modes of sex determination. Particularly the XYY multiple sex chromosome system shows a relatively low incidence among vertebrates, and it has not been yet thoroughly investigated. Previous research suggested two independent X-autosome fusions in which led to the emergence of XYY sex chromosome system in three of its species. In this study, we investigated evolutionary trajectories of synteny blocks involved in this XYY system by probing six species with whole chromosome painting (WCP) probes derived from the X (HCA-X) and the chromosome 9 (HCA-9) of . We found that both painting probes hybridize to two distinct chromosome pairs in Amazonian species, whereas the HCA-9 probe paints three chromosome pairs in endemic to Guyanese drainages. These findings demonstrate distinct evolutionary fates of mapped synteny blocks and thereby elevated karyotype dynamics in among the three evolutionary clades.