Chromosome Painting and the Evolution of Sex Chromosomes in the Erythrinidae Fish Family (Characiformes)

Abstract

The Erythrinidae family, although distributed throughout the Neotropical region, is relatively small among the Characiformes fish, comprising only three genera: Hoplias Gill, 1903, Hoplerythrinus Gill, 1895 and Erythrinus Scopoli, 1777. However, this family is broadly diversified concerning the karyotype structure, varying from several karyomorphs associated with the same nominal species to species groups with a conserved karyotypic structure. In particular, various sex chromosomes systems (single and multiple, in a nascent stage or highly differentiated) occur in this family, alongside with species lacking heteromorphic sex chromosomes. This project aims to use the excellent model found in the Erythrinidae fish to explore the processes of chromosomal diversification, particularly regarding the evolution and differentiation of the sex chromosomes. For these purposes will be used the methodological advances of the molecular cytogenetic, such as the mapping of repetitive DNA sequences on the chromosomes, microdissection and chromosome painting, to allow most effective exploitation of the events related to the chromosomal changes. The data to be obtained will enable progress in the knowledge of the chromosomal differentiation between populations and species, particularly between possible distinct species still related to a same nominal species by the classical taxonomy. At the same time, they also allow to clarify fundamental aspects of the sex chromosomes evolution among fishes, highlighting the occurrence of these chromosomes within species complexes, between different species of the same genus, as well as between different genera of the same family. Finally, the results will also be important contributions to understanding the evolutionary processes of the sex chromosome in vertebrates as a whole.