Shell colour diversification induced by ecological release: a shift in natural selection after a migration event

Ecological release is often attributed to the rapid adaptive diversification of phenotypic traits. However, it is not well understood how natural selection changes its strength and direction through the process of ecological release. Herein, we demonstrated how shell colour of the Japanese land snail Euhadra peliomphala simodae has diversified via a shift in natural selection due to ecological release after migration from the mainland to an island. This snail’s shell colour diversified on the island due to disruptive selection after migration from the mainland. We used trail-camera traps to identify the cause of natural selection on both the mainland and island. We then conducted a mark-recapture experiment while collecting microhabitat use data. In total, we captured and marked around 1700 snails on the mainland, some of which were preyed upon by an unknown predator. The trail-camera traps showed that the predator is the large Japanese field mouse Apodemus speciosus, and the predatory ...

生态释放（ecological release）常被归因于表型性状（phenotypic traits）的快速适应性分化。然而目前学界尚未明确自然选择如何在生态释放过程中改变其作用强度与方向。本研究揭示了日本陆生蜗牛*Euhadra peliomphala simodae*的壳色如何通过自然选择的转变实现分化——这一转变源于其从大陆迁移至岛屿后发生的生态释放事件。该蜗牛的壳色在从大陆迁入岛屿后，因岛上的分裂选择（disruptive selection）作用而发生分化。我们分别在大陆与岛屿布设红外触发相机陷阱，以明确两地自然选择的驱动因子。随后我们开展了标记重捕实验（mark-recapture experiment），并同步收集微生境（microhabitat）利用数据。总计我们在大陆捕获并标记了约1700只蜗牛，其中部分个体被一种未知天敌捕食。红外触发相机陷阱的监测结果显示，该天敌为日本大姬鼠（Apodemus speciosus），其捕食...