Speciation history of a species complex of Primulina eburnea (Gesneriaceae) from limestone karsts of south China, a biodiversity hotspot

Limestone karsts in southern China are characterized by high edaphic and topographic heterogeneity and host high levels of species richness and endemism. However, the evolutionary mechanisms for generating such biodiversity remain poorly understood. Here, we performed species delimitation, population genetic analyses, simulations of gene flow, and analyses of floral morphological traits to infer the geographic history of speciation in a species complex of Primulina eburnea from limestone karsts of south China. Using Bayesian species delimitation, we determined that there are seven distinct species that correspond well to the putative morphological species. Species-tree reconstruction, Structure and Neighbour-Net analyses all recovered four lineages in agreement with currently species geographic boundaries. High levels of genetic differentiation were observed both within and among species. Isolation–migration coalescent analysis provides evidence for significant but low gene flow among s...