Recent lake expansion triggered the adaptive radiation of freshwater snails in the ancient Lake Biwa.

Lake expansion that leads to the formation of new habitats has potential to drive intralacustrine diversification. The ancient Lake Biwa in central Japan has historically experienced substantial changes in the lake size, and it provides a useful system for evaluating the role of lake-size fluctuations in the diversification of endemic fauna. Here, we used genome-wide DNA analyses and reconstructed the diversification history of the endemic freshwater snails belonging to the subgenus with respect to the geological history of Lake Biwa.