Potential spatial distribution pattern and landscape connectivity of Pelophylax plancyi in Shanghai, China

Aims: Habitat fragmentation and loss caused by urbanization are important factors that threaten the survival of wildlife globally. Urbanization has caused amphibians to become one of the most severely threatened groups of terrestrial vertebrates. Studying the spatial distribution pattern and exploring how landscape connectivity affects the gene flow among fragmented populations of amphibians in urban areas would provide a deeper understanding of the impacts of urbanization on wildlife and offer theoretical guidance for local biodiversity conservation. Methods: In this study, we selected the eastern golden frog (Pelophylax plancyi) as the primary research subject and obtained landscape and environmental data about land cover, normalized difference vegetation index (NDVI) and land surface temperature in the Shanghai region using Landsat-8 satellite images (http://www.gscloud.cn). Combined with the data from field population survey, we employed the maximum entropy (MaxEnt) model to predict the spatial distribution pattern of P. plancyi in the region. We evaluated the potential corridors and calculated the resistance distances between local populations using circuit theory (Circuitscape), and explored the effect of geographical and resistance distance on genetic differentiation among local populations using the Mantel test of each local populations based on the genetic distance (F_ST) matrices calculated from simple sequence repeat (SSR) and single nucleotide polymorphism (SNP). Results: The habitat suitability of P. plancyi significantly decreased along the rural-to-urban gradient. NDVI was the main factor affecting the MaxEnt modelling and indicated that the P. plancyi prefer to inhabit areas with higher vegetation coverage. There was no significant correlation between genetic distance and geographical distance, while genetic distance increased significantly with the resistance distance. Conclusions: The protection and maintenance of continuous suitable habitats in suburbs and isolated habitat patches in urban areas that still exist is the primary measure of conservation for native amphibians such as P. plancyi. Furthermore, optimizing urban landscape structure, strengthening the construction of corridors suitable for various groups of wildlife, and promoting the gene exchange among local populations are effective methods to achieve the self-sustainment of populations and long-term conservation of biodiversity in urbanized areas.