Habitat fragmentation influences gene structure and gene differentiation among the Loxoblemmus aomoriensis populations in the Thousand Island Lake.

Thousand Island Lake (TIL) is a fragmented landscape consisting of more than 1000 land-bridge islands isolated during reservoir formation. To evaluate the effects of fragmentation and island attributes on insect populations, we examined the genetic structure of Loxoblemmus aomoriensis, a species of cricket widely distributed in TIL, and compared genetic diversity between islands samples. Population genetic analyses was conducted based on mitochondrial DNA haplotype frequencies of 10 sample islands. By comparing three island attributes with population genetic diversity reveals that island area influenced population genetic diversity (r2 = 0.5094, p = 0.00204). Using Pairwise Fst values, we also found that long-distance isolation increased the genetic differentiation, while short-distance isolation can be offset by dispersal. These results indicate that fragmentation can impact populations on a genetic level.