Patterns in the diversity and endemism of extant Eocene age lineages across southern Africa

Abstract

Southern Africa boasts a wealth of endemic fauna and flora, comprising both massive recent radiations such as those characteristic of the Cape flora, and solitary ancient species such as the peculiar desert gymnosperm Welwitschia. This study was undertaken to identify ancient biological lineages (tetrapod and vascular plant lineages of Eocene age or older) endemic to southern Africa, and to map their distribution across the region. Twenty-seven (17 plant and ten animal) lineages were identified, and distribution maps were generated for each of them across 74 operational geographic units, which were then combined into total endemism and corrected weighted endemism per unit area. Total endemism peaked along South Africa's coast and Great Escarpment, but in the case of weighted endemism high values were also recorded along other portions of the Great Escarpment further north. A review of the lineages sister to southern African ancient endemic lineages showed that these are often globally widespread, and many of them differ substantially from the southern African ancient lineages in terms of morphology and ecology. The mechanisms of ancient lineage survival in the region are discussed, and their importance for conservation in southern Africa is emphasised.