Influence of Pliocene and Pleistocene climates on hybridization patterns between two closely related oak species in China.

Our results highlight that paleoclimate change shapes present admixture patterns by influencing the extent of historical range overlap. Specifically, the mid-Pliocene warm climate promoted ancient contact, allowing widespread hybridization throughout central China. In contrast, the Pleistocene cool climate caused the local extinction of Q. chenii, reducing the probability of interspecific gene flow in most areas except the sites having a high level of ecological stability.