Genetic structure of a Japanese brown frog (Rana japonica) population implies severe restriction of gene flow caused by recent urbanization in a satoyama landscape

Rapid urbanization is one of the major pressures on amphibian species. Elucidating changes in genetic structure will be useful in evaluating the effects of urbanization on amphibian populations. Our study focused on Rana japonica, which is common in complex agricultural landscapes known as satoyama, which are also under intense development pressure. We conducted landscape genetic analyses based on mitochondrial DNA haplotype frequencies of 13 breeding sites in a rapidly urbanizing area of Japan. We found several breeding sites had significantly higher Fst values, and we also identified the barriers to gene flow between these sites. Observation of past aerial photographs revealed that these barriers coincided with the construction of man-made structures in the last few decades, suggesting that urbanization has restricted gene flow in R. japonica. Our results show that landscape genetic approaches are useful in conservation planning where rapid habitat degradation has taken place.