Whole genome-wide chromosome fusion and new gene birth in the Monopterus albus genome

BACKGROUND: Teleost fishes account for over half of extant vertebrate species. A core question in biology is how genomic changes drive phenotypic diversity that relates to the origin of teleost fishes. RESULTS: Here, we used comparative genomic analyses with chromosome assemblies of diverse lineages of vertebrates and reconstructed an ancestral vertebrate genome, which revealed phylogenomic trajectories in vertebrates. We found that the whole-genome-wide chromosome fission/fusions took place in the Monopterus albus lineage after the 3-round whole-genome duplication. Four times of genomic fission/fusions events resulted in the whole genome-wide chromosome fusions in the genomic history of the lineage. In addition, abundant recently evolved new genes for reproduction emerged in the Monopterus albus after separated from medaka. Notably, we described evolutionary trajectories of conserved blocks related to sex determination genes in teleosts. CONCLUSIONS: These data pave the way for a better understanding of genomic evolution in extant teleosts.