Geographic isolation enables recurrent pollinator shifts despite hybridisation in the Cape's hyperdiverse heathers

Deciphering the ecological and geographic factors that influence the dynamics of population divergence can aid in understanding why some groups of organisms diversify more prolifically than others. One such diverse group is the heathers (\textit{Erica}, Ericaceae), whose exceptional species richness in the Cape Floristic Region is enigmatic. Here, we study \textit{Erica abietina}, a small but highly variable species complex with four described subspecies differing in geographic range, habitat, and floral characters associated with pollination. To understand the factors and forces that shaped its evolution, we evaluate the status of the subspecies and test for hybridisation, introgression, pollinator-driven divergence, and geographic population structure using genotyping-by-sequencing on samples across the entire distribution.