Phylogeography, Species Limits, Phylogeny, and Classification of the Turacos (Aves: Musophagidae) Based on Mitochondrial and Nuclear DNA Sequences

Abstract

ABSTRACT We used mitochondrial and nuclear DNA sequences to examine patterns of differentiation and evolution in the Musophagidae, an avian family endemic to sub-Saharan Africa; attention was focused on the subfamily Musophaginae, the turacos, or louries. Phylogeographic analysis of 410 individual ND2 sequences from throughout the ranges of the currently recognized species revealed multiple instances of unexpectedly large genetic divergences and cryptic taxa. Within both montane and lowland species, including Tauraco hartlaubi and T. schalowi, Menelikornis leucotis, Musophaga macrorhyncha, and Gallirex johnstoni, fixed private haplotypes were found in disjunct portions of the ranges, suggesting negligible recent gene flow and evolutionary independence of populations. Two taxa originally described as subspecies (T. schalowi loitanus and T. s. marungensis), but not recognized for over 50 years, were found to be 100% diagnosable based on the mitochondrial sequences. The data also revealed the existence of two polyphyletic traditional species, Tauraco livingstonii and T. schuettii, as well as the polyphyly or paraphyly of all traditional superspecies complexes involving members of the genus Tauraco. Overall, our analyses of genetic and morphological variation revealed substantial and unexpected geographic diversity within the Musophagidae. We recognize 33 species-level taxa that represent the appropriate units for phylogenetic and biogeographic analyses (phylogenetic species). We used complete mitochondrial ND2 sequences and nuclear DNA sequences of an Aconitase intron and of the RAG-1 exon to infer the phylogenetic relationships among those species. The results include all the phylogenetic species and, for the first time, nuclear data. We present a new classification of the Musophagidae based on our phylogeographic and phylogenetic results. We allocate the 33 species to seven previously recognized genera, an average of 4.7 species per genus.