title: The role of ecological factors in determining phylogeographic and population genetic structure of two sympatric island skinks (Plestiodon kishinouyei and P. stimpsonii).
abstract: We conducted comparative phylogeographic and population genetic analyses of Plestiodon kishinouyei and P. stimpsonii, two sympatric skinks endemic to islands in the southern Ryukyus, to explore different factors that have influenced population structure. Previous phylogenetic studies using partial mitochondrial DNA indicate similar divergence times from their respective closest relatives, suggesting that differences in population structure are driven by intrinsic attributes of either species rather than the common set of extrinsic factors that both presumably have been exposed to throughout their history. In this study, analysis of mtDNA sequences and microsatellite polymorphism demonstrate contrasting patterns of phylogeography and population structure: P. kishinouyei exhibits a lower genetic variability and lower genetic differentiation among islands than P. stimpsonii, consistent with recent population expansion. However, historical demographic analyses indicate that the relatively high genetic uniformity in P. kishinouyei is not attributable to recent expansion. We detected significant isolation-by-distance patterns among P. kishinouyei populations on the land bridge islands, but not among P. stimpsonii populations occurring on those same islands. Our results suggest that P. kishinouyei populations have maintained gene flows across islands until recently, probably via ephemeral Quaternary land bridges. The lower genetic variability in P. kishinouyei may also indicate smaller effective population sizes on average than that of P. stimpsonii. We interpret these differences as a consequence of ecological divergence between the two species, primarily in trophic level and habitat preference.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto, 606-8502, Japan. kurita@zoo.zool.kyoto-u.ac.jp.
authors.forename: Kazuki
authors.identifier: http://orcid.org/0000-0001-5709-9425
authors.initials: K
authors.lastname: Kurita
authors.affiliation: Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa, 903-0213, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Toda
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D004463:Ecology; D017753:Ecosystem; D049810:Genetic Speciation; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D006239:Haplotypes; D062312:Islands; D008116:Lizards / Q000145:classification / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics*; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D061350:Sympatry
chemical_list: D004272:DNA, Mitochondrial
keywords: Filter bridge; Phylogeography; Population genetics; Reptile; Ryukyu Archipelago; Scincidae