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Abstract: The Oita salamander Hynobius dunni Tago, 1931, endemic to eastern Kyushu and western Shikoku of southwestern Japan, is a lowland lentic breeder and has declined throughout its distribution range. To contribute to the future conservation of this salamander, current population genetic structures and genetic diversities were examined for 12 populations of eastern Kyushu, using a mitochondrial cytochrome b gene and three microsatellite loci. Populations were found to be genetically separated into northern and southern groups, and microsatellite analysis showed some genetic differences even in the northern regions. The southern group was restricted to a narrow area and had low genetic diversity in both mitochondrial and microsatellite DNAs. In the northern group, the mitochondrial and microsatellite DNA diversities were also low in some peripheral populations. For the accurate genetic management of this species, we need to pay more detailed attention to such genetic differentiation and diversity.
Key words: Genetic differentiation; Genetic diversity; Microsatellite DNA; Mitochondrial DNA; Oita salamander
Introduction
The effects of habitat fragmentation are now unavoidable for wild animals living in inhabited areas. Fragmentation is caused by agriculture, forestry, and other human activities (e.g., urban development), and they can produce geographic barriers to the dispersal of animals (Kolozsvary and Swihart, 1999). If their dispersal ability is very low, humaninduced habitat fragmentation produces many small, isolated populations. Even in wellconserved forest areas, construction of roads can severely divide populations of animals with very low mobility (Trombulak and Frissell, 2000). Small populations are very susceptible to stochastic events, which often result in extinction ( Frankham e t a l., 2 002). S uch populations also tend to have less genetic diversity than larger ones due to the loss of alleles through genetic drift and the increased chance of inbreeding (Frankham et al., 2002). Therefore, once the species distribution range becomes heavily fragmented and gene flow is limited by rare dispersal events, we must manage such populations carefully to avoid extinction and to understand the species ecology, demography, and genetics (Frankham et al., 2002). Recent development of molecular techniques enables us to assess, on a fine scale, population genetic structure in the wild. Such population genetic data are available for monitoring genetic diversity (Schwartz et al., 2007), identifying management units to conserve (Palsbøll et al., 2007),...