Phylogeography of the two smooth skinks, Scincella boettgeri and S. formosensis (Squamata: Scincidae) in the Southern Ryukyus and Taiwan, as inferred from variation in mitochondrial cytochrome b sequences.

Scincella boettgeri and S. formosensis are respectively small-bodied, morphologically similar skinks, endemic to the Southern Ryukyus and Taiwan. To estimate the phylogeography of both species, we performed phylogenetic analyses using the mitochondrial cytochrome b (cyt b) gene sequences based on 102 individuals of S. boettgeri from 12 Southern-Ryukyu islands and 33 S. formosensis from six localities in Taiwan. A total of 67 haplotypes were recognized for S. boettgeri and 21 for S. formosensis. The phylogenetic analyses revealed that the populations of Scincella spp. in the Southern Ryukyus and Taiwan are composed of three major clades, the Yonagunijima clade from Yonagunijima Island, the Southern-Ryukyu clade from the Southern Ryukyus exclusive of Yonagunijima Island, and the Taiwan clade from Taiwan. These clades showed high levels of genetic divergence, suggesting that the species have been isolated since the Early Pliocene. The Southern-Ryukyu and Taiwan clades were further divided into three and four subclades, respectively. Two of the three Southern-Ryukyu subclades are partially sympatric on two islets of the Yaeyama Group, suggesting this population represents a secondary contact subsequent to their allopatric differentiations.