Molecular differentiation and morphological variation in lizards of the tribe Iphisini (Squamata, Gymnophthalmidae)

Species delimitation is essential for characterization and conservation of biodiversity. Nevertheless, it represents a challenge for groups in which morphological variation is subtle, such as the microteiid lizards of the tribe Iphisini. Eight species from six genera are currently recognized in the tribe but recently, based on molecular analysis and hemipenial anatomy, four candidate species were inferred for Iphisa. The phylogenetically related tribe Gymnophthalmini presents higher species richness and morphological diversity, specially in forms with adaptations to fossoriality. Nevertheless, the historical and ecological mechanisms involved in the distinct speciation patterns are poorly known, although geographical isolation have been historically emphasized for neotropical biota. In recent times, quantitative methods were developed to address evolutionary questions such as speciation probabilities, variation in diversification rates and reconstruction of historical demography of populations and migration. In this study I used a combination of quantitative methods based on molecular, morphological and environmental data for testing the hypothesis that: there is unrecognized diversity within Iphisini; differences in species richness and disparity among Iphisini and related tribes are congruent with differences in time and mode of diversification; and that diversification in Acratosaura occurred with geographical isolation caused by paleoclimatic fluctuations. Based on the results of molecular analyses, four candidate species were delimited for Iphisini, rising in 33% the tribe diversity. There was no significant variation in morphometry between candidate species of Acratosaura. The phylogeny of Gymnophthalminae presented high support for the relationship between Iphisini and Heterodactylini, and showed diversification timming and species richness comparable between this clade and Gymnophthalmini. The tribes presented similar diversification patterns but distinct rates. The patterns of morphological evolution were congruent with diversification patterns in Gymnophthalmini but distinct in Heterodactylini sensu lato, indicating that disparity is independent from diversification in the group. The phylogeographic analyses indicate that populations of Acratosaura presented demographic and spatial stability through time, with evidences of gene flow among lineages after differentiation. Thus, the results suggest that diversification of Acratosaura was not influenced by variations in historical climate, and probably occurred without complete reproductive isolation (AU)