Phylogenetic analysis and study of sex and B chromosomes of Physalaemus (Anura, Leiuperidae): a contribution to the analysis of the karyological evolution in the genus

Abstract

The genus Physalaemus is very interesting for chromosomal evolutionary studies. Several species of this genus were already karyotyped and, among all of them, only Physalaemus ephippifer showed heteromorphic sex chromosomes, suggesting Physalaemus as a valuable genus for studies of processes involved in the sex chromosomes differentiation. Despite that, a proper comparative analysis of the available karyotypes is not possible, since interspecific chromosomal homeologies are not easily recognized. Another interesting cytogenetic finding concerning this genus is the B chromosome of P. feioi. Aiming to contribute to the chromosomal studies of this genus, one of the goals this proposal is the phylogenetic analysis of Physalaemus species. This proposal also intends a better characterization of the B chromosome of P. feioi and the chromosomes of P. ephippifer, aiming the description of new chromosomal markers for this latter, with special interest in those concerning its sex chromosomes. The phylogenetic relationships will be inferred from the nucleotide sequences of the mitochondrial genes 12S, 16S and tRNA-Val, by parsimony and Bayesian methods. For studying the molecular nature of the B chromosome of P. feioi, microdissection and chromosome painting will be made. For P. ephippifer studies, new populations will be karyotyped, repetitive DNA sequences will be isolated and chromosome painting of the sex chromosomes will be performed. (AU)