Phylogenetic relationships and speciation patterns in an African savanna dwelling bird genus (Myrmecocichla)

Abstract

Phylogenetic relationships among eight of nine Myrmecocichla chat species were inferred from DNA data. Bayesian posterior probabilities and maximum-likelihood bootstrap percentages strongly supported most branches in the phylogeny. Based on these results, Myrmecocichla, as currently defined, is not monophyletic. The results indicated that Myrmecocichla albifrons is part of a Cercomela+Oenanthe clade, whereas Oenanthe monticola is shown to be a Myrmecocichla. In addition, Myrmecocichla arnotti is shown to be polyphyletic. Phylogenetic analyses support three Southern versus Eastern or Northern speciation events. The dating of these speciation events suggests that they correspond to periods when the Afrotropical forests were expanded to coastal Kenya, 3-5Mya. This forest expansion thus served as a vicariant driver of speciation in the genus, a result consistent with speciation patterns in other arid-adapted African bird genera. Our haplotype analysis within one of the most widespread and habitat diverse Myrmecocichla species (formicivora, a southern African endemic) showed little genetic variation. Along with speciation patterns shown for Myrmecocichla and other avian genera, this lack of standing variation would appear to support large, inter-regional drivers of speciation as having the largest effect on the diversification of arid-adapted Africa bird species, which is in stark contrast to other vertebrate lineages whose genetic structure often shows strong intra-regional effects. © 2012 The Linnean Society of London.