Data from: Highly conserved Z and molecularly diverged W chromosomes in the fish genus Triportheus (Characiformes, Triportheidae)

The main objectives of this study were to test (i) if the W chromosome differentiation matches to species' evolutionary divergence (phylogenetic concordance) and (ii) if sex chromosomes share a common ancestor within a congeneric group. The monophyletic genus Triportheus (Characiformes, Triportheidae) was the model group for this study. All species in this genus so far analyzed have ZW sex chromosome system, where the Z is always the largest chromosome of the karyotype, while the W chromosome is highly variable ranging from almost homomorphic to highly heteromorphic. We applied conventional and molecular cytogenetic approaches including C-banding, rDNA mapping, comparative genomic hybridization (CGH) and cross species whole chromosome painting (WCP) to test our questions. We developed Z and W chromosome paints from T. auritus for cross species WCP and performed CGH in a representative species (T. signatus) to decipher level of homologies and rates of differentiation of W chromosomes. Our study reveled that the ZW sex chromosome system had a common origin, showing highly conserved Z chromosomes and remarkably divergent W chromosomes. Notably, the W chromosomes have evolved to different shapes and sequence contents within ~15-25 MYA of divergence time. Such differentiation highlights a dynamic process of W chromosome evolution within congeneric species of Triportheus.