Genetic Relationships of a Morphologically Unique Population of the Genus Eumeces (Scincidae: Squamata) from Iotorishima Island, Ryukyu Archipelago, as Revealed by Allozyme Data.

Abstract

The Ryukyu five-lined skink, Eumeces marginatus, is an endemic species of the central and northern Ryukyus, and is composed of two morphologically defined subspecies, E. m, marginatus from the Okinawa Group, and E. m. oshimensis from the Amami and Tokara Groups.

Molecular Phylogeography of the Endemic Five-lined Skink (Plestiodon marginatus) (Reptilia: Scincidae) of the Ryukyu Archipelago, Japan, with Special Reference to the Relationship of a Northern Tokara Population1

“…With respect to the Okinoerabujima population, allozyme analyses demonstrated its closer relationship with populations of the nominotypical subspecies of the Okinawa Group including Kumejima than with those of P. m. oshimensis of the Amami Group and southern Tokara islands (Kato et al 1994, Motokawa et al 2001. Our results confirmed closer affinity of the Okinoerabujima population to the Okinawa Group populations and went even further to associate the former directly with the Okinawajima population by placing the Kumejima population externally (Figure 2).…”

“…Our results strongly suggest that neither of the currently designated subspecies of P. marginatus is monophyletic. To minimize frequency in taxonomic changes, however, we defer revision of subspecific classification of P. marginatus to future studies using additional samples representing the other taxonomically crucial populations, such as those from Kuchinoshima and Suwanosejima of the northern Tokara islands, Tokunoshima and Yoronjima of the Amami Group, and isolated Iwotorishima (Kato et al 1994, Motokawa et al 2001, Motokawa and Hikida 2003. Further resolution of the process of divergence of P. marginatus and related taxa in the East Asian islands with substantial statistical support will also require sequence data for additional mitochondrial genes, as well as for some nuclear genes.…”

“…For example, the Nakanoshima population, assigned to the subspecies P. m. oshimensis in the latest classification (Hikida 2002), was indicated to be closer to the nominotypical Okinawa Group populations than to the geographically much closer (Figure 1) southern Tokara and Amamioshima (type locality of P. m. oshimensis) populations (Motokawa and . A population of Okinoerabujima (a southern island of the Amami Group), usually assigned to P. m. oshimensis on the basis of tail color pattern, was also shown to be closer to the nominotypical subspecies of the Okinawa Group than to the consubspecific populations of Amamioshima and adjacent islands (Kato et al 1994, Motokawa et al 2001.…”

“…To remedy this situation, we examined the phylogenetic relationships of representative populations of P. marginatus, P. japonicus, and other species of the latiscutatus speciesgroup by analyzing mitochondrial 12S and 16S rRNA genes. Our purposes were to assess the phylogenetic hypotheses proposed by Kato et al (1994), Motokawa et al (2001), and Motokawa and Hikida (2003), and to discuss historical biogeography and subspecific classification of P. marginatus.…”