title: An investigation for population maintenance mechanism in a miniature garden: genetic connectivity or independence of small islet populations of the Ryukyu five-lined skink.
abstract: The Ryukyu five-lined skink (Plestiodon marginatus) is an island lizard that is even found in tiny islets with less than half a hectare of habitat area. We hypothesized that the island populations are maintained under frequent gene flow among the islands or independent of each other. To test our hypotheses, we investigated genetic structure of 21 populations from 11 land-bridge islands that were connected during the latest glacial age, and 4 isolated islands. Analyses using mitochondrial cytochrome b gene sequence (n = 67) and 10 microsatellite loci (n = 235) revealed moderate to high levels of genetic differentiation, existence of many private alleles/haplotypes in most islands, little contemporary migration, a positive correlation between genetic variability and island area, and a negative correlation between relatedness and island area. These evidences suggest a strong effect of independent genetic drift as opposed to gene flow, favoring the isolation hypothesis even in tiny islet populations. Isolation-by-distance effect was demonstrated and it became more prominent when the 4 isolated islands were excluded, suggesting that the pattern is a remnant of the land-bridge age. In a few island populations, however, the possibility of occasional overwater dispersals was partially supported and therefore could not be ruled out.
authors.affiliation: From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda). kurita@zoo.zool.kyoto-u.ac.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kurita
authors.affiliation: From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda).
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hikida
authors.affiliation: From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda).
authors.forename: Mamoru
authors.initials: M
authors.lastname: Toda
mesh_terms: D000483:Alleles; D000818:Animals; D001499:Bayes Theorem; D004272:DNA, Mitochondrial / Q000235:genetics; D051456:Gene Flow; D040961:Genetic Drift; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006239:Haplotypes; D062312:Islands; D007564:Japan; D016013:Likelihood Functions; D008116:Lizards / Q000235:genetics*; D018895:Microsatellite Repeats; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial
keywords: Plestiodon marginatus; genetic structure; islands; microsatellite; mitochondrial DNA