Parallel gigantism and complex colonization patterns in the Cape Verde scincid lizards Mabuya and Macroscincus (Reptilia : Scincidae) revealed by mitochondrial DNA sequences

The scincid lizards of the Cape Verde islands comprise the extinct endemic giant Macroscincus coctei and at least five species of Mabuya, one of which , Mabuya vaillanti, also had populations with large body size. Phylogenetic analysis based on DNA sequences derived from the mitochondrial cytochrome b, cytochrome oxidase I and 12S rRNA genes (711, 498 and 378 base pairs (bp ), respectively) corroborates morphological evidence that these species con stitute a clade and that Macroscincus is unrelated to very large skinks in other areas. The relationships are ((M. vaillanti and Mabuya delalandii) (M abuya spinalis and Macroscincus coctei (Mabuya fogoensis nicolauensis (Mabu ya fogoensis antaoensis and Mabuya stangeri)))). The Cape Verde archipelago was colonized from West Africa, probably in the Late Miocene or Early Plio cene period. The north-eastern islands were probably occupied first, after which the ancestor of M. vaillanti and AT. delalandii may have originated o n Boavista, the ancestor of the latter species arriving on Santiago or Fogo later. The M.fogoensis-M. stangeri clade colonized the islands of Branco, Razo, Santa Luzia and Sao Vicente from Sao Nicolau and reached Santo Antao after this. Colonization of these northeastern islands was slow, perhaps be cause the recipient islands had not developed earlier or because colonizati on cut across the path of the Canary Current and the Northeast Trade -Winds , the main dispersing agents in the region. Rapid extension of range into t he southwestern islands occurred later in M. spinalis and then in AY. vaill anti and M. delalandii. The long apparent delay between the origin of these species and their southwestern dispersal may have been because there were earlier colonizations of the southern islands which excluded later ones unt il the earlier inhabitants were exterminated by volcanic or climatic events . The evolution of large size in Macroscincus occurred in the northwestern islands and was paralleled in the eastern and southern islands by populatio ns of M. vaillanti. Both cases of size increase in Cape Verde skinks were a ccompanied by the development of herbivory.