Phylogeography and venom composition of the rinkhals, Hemachatus haemachatus (Squamata: Elapidae)

Abstract

Phylogeographic patterns as well as divergence date estimates and the past population demography of Hemachatus haemachatus were analysed using nuclear and mitochondrial genetic markers. My results suggest that H. haemachatus forms a continuous population that diverged into two broad lineages due to glacial and interglacial cycles during the Plio-Pleistocene interval. During this interval, stable populations existed in the southern Cape and eastern inland regions of southern Africa. These cycles lead to further isolation and genetic differentiation of populations within these lineages during the Tarantian stage of the Pleistocene epoch. Currently, limited genetic variation exists between the lineages, suggesting that gene flow was restricted for a limited period only, and subsequently re-established. This most likely occurred as a result of a range expansion during the Last Glacial Maximum (LGM) which led to increased open grassland habitats. In addition to genetic analyses, I examined the venom composition of this species across its distribution using bottom-up approaches, which incorporated rp-HPLC, SDS-PAGE and MS/MS analysis. A total of 20 protein families were identified from six venom pools. I found that the major components of the venom were shared between all populations sampled, although slight variations were observed. The venom was rich in cytotoxic and neurotoxic elements. Cardiotoxic and hemorrhagic elements were also present. I did not observe a definitive link between phylogeographic patterns and the proteomic composition at the protein family level.