Diversification in North American arid lands: Niche conservatism, divergence and expansion of habitat explain speciation in the genus Ephedra

► We inferred relationships and divergence time of North America Ephedra species. ► We compared climatic conditions of sister species using tests of niche evolution. ► Our results mostly suggest climatic niche conservatism, with one exception. ► Divergence time coincides with an increase of arid lands in North America. ► We suggest that diversification is related to habitat expansion.