Cytogenetic and phylogenetic analysis of the complex Physalaemus cuvieri - P. ephippifer (Anura, Leptodactylidae)

Abstract

High level of genetic and cytogenetic variation has been found among populations assigned to the taxa Physalaemus cuvieri and Physalaemus ephippifer. Species delimitation analyses based on DNA sequences suggest the presence of at least four species in this group, which is referred to as Physalaemus cuvieri - Physalaemus ephippifer complex. Although low genetic divergence between P. ephippifer and the Lineage 1 of "P. cuvieri" had been observed based on the analysis of mitochondrial DNA sequences, some mitochondrial signatures could be assigned to each of these lineages. Cytogenetic features also distinguish these two lineages, and evident sex chromosome heteromorphism is exclusively found in P. ephippifer. The presence of mitochondrial haplotypes from P. ephippifer as well as from the Lineage 1 of "P. cuvieri" among specimens from São Pedro da Água Branca-MA, which is located between the geographic area occupied by P. ephippifer and that where individuals from the Lineage 1 of "P. cuvieri" are found, raised the hypothesis of secondary contact between these lineages. However, the small size of the studied sample prevented the assessment of this hypothesis. The cytogenetic data available for specimens from São Pedro da Água Branca are also scarce, being restricted to few males. Therefore, the genetic and cytogenetic study of specimens from the area that includes São Pedro da Água Branca emerges as especially relevant, either for better understanding the diversity in the P. cuvieri - P. ephippifer complex, or for evaluating whether the cytogenetic differences observed between the lineages could have played any role in the evolutionary dynamics of these anurans. Therefore, in the present study we will analyze specimens from the area that includes São Pedro da Água Branca, with the goal of evaluating the hypothesis of introgression between P. ephippifer and the Lineage 1 of "P. cuvieri" as well as the cytogenetic divergence in this group. Phylogenetic inferences and genetic diversity analyses will be conducted based on RAD-seq data and mitochondrial sequences H1 (which include the genes 12S, 16S and RNAt-val). The ABBA/BABA test for introgression will be run with the RAD-seq data. Chromosomal preparations will be obtained from specimens from the region that includes São Pedro da Água Branca and the karyotypes of these animals will be compared to the karyotypes of P. ephippifer and the Lineage 1 of "P. cuvieri". The cytogenetic data will be integratedly analyzed with those derived from the analyses of DNA sequences. (AU)