Morphometric Variability in Lizards of the Genus Teius: A Comparative Study of Species with Different Reproductive Modes

Abstract

The lizard genus Teius is widely distributed in lowland areas to the east of the Andes in southern South America and includes three species: Teius teyou, T. oculatus, and T. suquiensis. All three Teius species are broadly similar in morphological characters, the dorsal coloration pattern being the best feature to distinguish them. Furthermore, T. suquiensis are parthenogenetic, whereas the other two are bisexual. We applied 2D geometric morphometric methods on head morphology to measure and compare variability between these clonally and sexually reproductive lizards and to assess form variability among populations within the parthenogenetic species. We studied 181 adult females of the three species from across a wide range of their distributions. Geometric morphometrics successfully separated them in the morphospace. The three Teius presented similar head size; hence, the differences found are related to shape. Teius teyou has a shorter snout and a narrower posterior area of the head whereas T. oculatus has a longer snout and a wider posterior area of the head, and T. suquiensis shows an intermediate phenotype. Levels of morphological variability among the species were similar and independent of reproductive mode. Differences in head size and shape among populations were observed within T. suquiensis, despite its clonal inheritance. The observed variability might be explained by populations that are composed of different clonal lineages, populations that showed different responses to varying local environmental factors, or both. Additional morphological studies considering genetic diversity and habitat characteristics may clarify the factors that promote morphological variability in the genus, especially in the parthenogenetic species.