2018 Volume 23 Issue 2 Pages 245-256
In Japan, a yatsuda is a poorly drained traditional paddy field surrounded by a hilly forested landscape. Yatsudas are biodiversity hotspots, although urbanization is currently causing fragmentation and isolation of these habitats. The Japanese brown frog (Rana japonica) is a yatsuda indicator species that is on red lists in most prefectures in the Kanto region. The habitats and breeding ecology of this species have been well studied; however, little information about fine-scale (100 m to 5 km) isolation of breeding populations is available. We analysed the genetic structure and diversity of breeding-site populations in the suburban landscape of Chiba, Japan. Four major populations were genetically differentiated, to various extents, and we detected gene flow restriction between breeding sites upstream and downstream of the Sakatsuki River. Small breeding population sizes in suburban landscapes can cause unique genetic compositions, and isolation among populations might maintain such differences. Creating terrestrial vegetation corridors and small puddles beside rivers for use as stepping stones might be effective conservation measures.
