A molecular phylogeny of African kestrels with reference to divergence across the Indian Ocean

Abstract

In this paper we examine the evolutionary relationships of kestrels from mainland Africa, Indian Ocean islands and related areas. We construct a molecular phylogeny of African kestrels, using approximately 1.0 kb of mitochondrial cytochrome b sequence. Our molecular results support an Old World origin for typical kestrels and an ancient divergence of kestrels into the New World, and indicate a more recent radiation of kestrels from Africa via Madagascar towards Mauritius and the Seychelles. Phylogenetic placement of the Australian kestrel suggests a recent origin from African kestrel stock. We compare evolutionary relationships based on kestrel plumage pattern and morphology to our molecular results for the African and Indian Ocean kestrels, and reveal some consistency with the different island forms. We apply a range of published avian cytochrome b substitution rates to our data, as an alternative to internal calibration of a molecular clock arising from incomplete paleontological information. We align these divergence estimates to the geological history of Indian Ocean island formation inferred from potassium–argon dating methods. The arrival of kestrels on Mauritius appears consistent with the cessation of volcanic activity on Mauritius. The estimated time and route of divergence of the Seychelles kestrel from Madagascar may be compatible with the emergence of smaller islands during Pleistocene sea level fluctuations.