Timing and origins of Mexican and Central American oak diversity

25 Mya. This coincides with a variety of ecosystem changes at the Oligocene-Miocene boundary, including aridification. Diversification analyses reveal that montane habitats acted as cradles of oak diversity, with higher speciation rates associated with movement into topographically complex, higher-elevation landscapes. Despite 20 Ma of independent evolution in Mexico and Central America, red and white oaks show remarkable convergent evolution in climate niche. Our results highlight how extrinsic factors-migration into novel environments-coupled with intrinsic niche lability can facilitate rapid diversification. Our study thus provides insights into the origins of temperate biodiversity and the evolutionary processes shaping species-rich montane ecosystems.