Trophic Niche Shifts in Mountain Feirana Frogs under Human-mediated Habitat Transformations

Urbanization can induce environmental changes, disturbing habitat transformation process, and resulting in niche shift of species and local extinctions. Amphibians have experienced worldwide population declines, with habitat loss acting as one of the most disruptive causes. How amphibian species response to changing habitats could be reflected in their utilization and assimilation of resources. Using stable isotopes, we explored trophic niche variation between natural and transformed habitats for three closely related frog species in the genus Feirana (F. quadranus, F. taihangnica and F. kangxianensis). Our results indicated that the delta C-13 value was negatively correlated with body size (snout-vent length) and the delta N-15 value increased along with the ontogenetic process. The delta C-13 values were significantly different among habitat types, and the variation of delta N-15 values was relatively limited in different disturbed gradients. Urban groups displayed broader trophic niche width than both rural and natural groups. When species in sympatry, their resource utilization and trophic niche overlap probability were more similar in rural habitats than their natural counterparts. Our findings would be conducive to understand trophic niche and function variation in amphibians during the urbanization process, allowing for effective predictions of ecological consequences of habitat transformation. This study can also provide insight into conservation strategies for mountain amphibians in the Anthropocene.