Effects of landscape features on gene flow among urban frog populations

Abstract

AbstractThe anthropogenic fragmentation of habitats has altered the distribution and size of populations of many species worldwide. To predict fate of populations and establish management practices that ensure their viability, we need to understand the demographic and genetic consequences of fragmentation. In this study, we analyzed whether the spatial configuration of remnant habitat patches within a fragmented landscape has shaped the patterns of genetic diversity and differences in local populations of the Montane brown frog (Rana ornativentris) in Tokyo, Japan. The species inhabits secondary forests and is particularly affected by fragmentation due to its habitat selectivity and low dispersal capability. We determined allele frequencies of six microsatellites to estimate genetic diversity of 33 local populations and pairwise genetic distances among them. Habitat suitability maps were developed based on two models, one with only climatic and topography as predictor variables (HSn), the second incorporating the potential barrier effect of urbanization as an additional variable (HSu). Ecological distances were calculated using the circuit theory applied to the habitat suitability maps. We found that within‐population genetic diversity decreases as the HSu habitat suitability decreases. Moreover, pairwise population genetic distance showed the highest correlations with resistance (i.e., ecological) distances when the HSu map was used. Our results confirmed the expectation that urbanized lands are barriers to gene flow, and that habitat fragmentation restricts inter‐population dispersal, thus reducing the genetic diversity of local populations. Our results also demonstrate that landscape genetics is a useful approach for identifying key factors affecting dispersal.