Molecular phylogeny, biogeography and insights into the origin of parthenogenesis in the Neotropical genus Leposoma (Squamata: Gymnophthalmidae): Ancient links between the Atlantic Forest and Amazonia

Abstract

Leposoma is a conspicuous component of leaf litter herpetofauna of South and Central American rainforests. The 15 bisexual and one parthenogenetic species are allocated to the parietale and scincoides groups based on morphology. Phylogenetic analyses of 1830 bp (mtDNA + nuclear) were performed on 63 specimens of four species from Amazonian and Panamanian rainforests, and six species and one undescribed form from the Atlantic Forest. Different methods of tree reconstruction were explored, with Anotosaura vanzolinia and Colobosauroides cearensis as outgroups. The monophyly of the parietale and scincoides groups is strongly supported. Contrary to previous hypotheses suggesting a recent contact between Atlantic and Amazon forests, our estimates point to an initial split in Miocene. The position of Leposoma baturitensis, endemic to relictual forests in the semiarid Caatingas northeastern Brazil, and its divergence from the remaining species of the Atlantic Forest, suggests an ancient isolation with no indication of a secondary contact with forests of the eastern coast. Our data do not permit unambiguous assignment of parental species of the unisexual Leposoma percarinatum or the mechanism involved in the origin of parthenogenesis, but revealed two highly divergent diploid and triploid lineages within L. percarinatum, indicating that the unisexuals represent a species complex.