Strong predation pressure by invasive predators can induce not only demographic decrease but also rapid adaptive morphological change of native prey. However, no study has reported about adaptive changes of native species caused by invasive mongoose, a globally well-known carnivore that seriously impacts on native fauna on islands.

Invasive mongoose was introduced to Amami Island Japan in 1979, and the introduction caused drastic decrease of native frog. We recorded morphology (snout-vent length, tibia length, head width, etc.) of the native frog at places with different impacts by the invader in Amami Island. We modeled by generalized least square methods to test the effect of potential factors (index of mongoose impact, topography, etc.) on morphology. We will discuss the potential factors determining the morphological variations, and the possibility of rapid morphological change driven by invasive mongoose.