Ecologia evolutiva do lagarto Brasiliscincus heathi (squamata: mabuyidae): filogeografia, autoecologia e parasitismo na Caatinga brasileira

Abstract

The Neotropical region has a long history of diversification and maintenance of biodiversity. However, the processes that shaped the origin and spatial patterns of lineages are still poorly understood. The group comprising the herpetofauna has been the focus of phylogeographic studies aimed at understanding evolution, speciation mechanisms, extinction, and changes in the distribution of organisms in tropical regions. The lizard genus Brasiliscincus includes three species restricted to South America: Brasiliscincus agilis, B. caissara, and B. heathi. The main taxonomic challenge for this genus has been establishing diagnostic characters, since most of the scale characters used show high overlap between species, making it difficult to define distribution limits, origin, and evolutionary history. Thus, we used phylogeographic inferences to understand the evolutionary history of the genus Brasiliscincus (B. agilis, B. caissara, B. heathi) occurring in the Caatinga and adjacent areas. In parallel, we investigated potential variations in ecological aspects of the lizard B. heathi, including diet, reproduction, sexual dimorphism, and parasitism, in relation to its geographic distribution in the Caatinga. We collected tissue samples covering the entire distribution of all three species, totaling 135 samples, and used mitochondrial genetic markers (COI and 16S) for genetic reconstruction through Bayesian and historical-demographic analyses. BAPS identified two populations of B. heathi: the first consisting of individuals distributed north of the São Francisco River, and the second south of the river, along with an additional unknown lineage associated with high-altitude regions in Bahia. We used four lineage delimitation methods, and except for ASAP, all others recovered six lineages within the complex. To infer aspects of the natural history and parasitism in B. heathi, we examined 293 individuals from 48 localities in the Caatinga. We identified 14 prey categories, with the index of relative importance ranging from 0.15 to 25.62. Random Forest analysis selected snout-vent length (SVL) and limb spacing as the most important variables for distinguishing sexes based on body shape. Regarding reproductive aspects, results show a positive relationship between female SVL and the number of embryos. In terms of parasitism, we found 339 endoparasites, with an overall prevalence of 57.44%. Mean abundance was 2.39 ± 0.31, range (0–21), and mean infection intensity was 4.79 ± 0.48 (1–22). North of the São Francisco River, we observed higher species richness (5 spp.), with Oochoristica sp. and Parafaringodon hispidus being the most prevalent. GLM models showed that SVL was the most important variable for endoparasite abundance across the entire sample, and Oochoristica sp. abundance was influenced by both sex and geographic group. Four species of endoparasites represent new records for the host.