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.

解析影响种群分化动态的生态与地理因子，有助于阐释为何部分生物类群的物种分化速率远高于其他类群。此类物种多样性极高的类群之一即为欧石楠类植物（heathers），隶属于欧石楠属（Erica）、杜鹃花科（Ericaceae）；该类群在开普植物区（Cape Floristic Region）的物种丰富度异乎寻常，这一现象长期以来令人费解。本研究以松叶欧石楠（*Erica abietina*）为对象，该类群为体型小巧但变异度极高的物种复合体，其下已定名4个亚种，各亚种在地理分布范围、栖息生境以及与传粉相关的花部特征上均存在差异。为阐明塑造其演化历程的因子与动力，本研究通过对覆盖其整个分布范围的采样样本开展基于测序的基因分型（genotyping-by-sequencing）分析，对各亚种的分类地位进行评估，并对杂交、基因渐渗、传粉媒介驱动的分化以及种群地理结构展开检验。