Genetic and morphological evidence for two species in the Udzungwa forest partridge Xenoperdix udzungwensis

Abstract

The Udzungwa forest partridge, Xenoperdix udzungwensis is known from only three forests within the Udzungwa and Rubeho Highlands of the Eastern Arc Mountains. Given the phenotypic differences between the Udzungwa (X. u. udzungwensis) and Rubeho Highland (X. u. obscurata) populations, it seems unlikely that there remains recurrent gene flow between these two populations. We used a combination of mitochondrial (1041 bp of NADH Dehydrogenase subunit 2) and nuclear DNA (569 bp of Fibrinogen intron 5 and 387 bp of Glyceraldehyde-3-phosphate Dehydrogenase intron 11) markers to investigate the degree to which these two taxa are separated. In mtDNA, 0.5% sequence divergence, with five-fixed mutational differences (two amino acid changes) was recovered between X. u. udzungwensis and X. u. obscurata. One fixed difference was found for Fib5 and none for Gadph11. Coalescent models suggest that no gene flow is taking place between the Udzungwa and Rubeho Highlands and that divergence between the two taxa took place about 200 000 years before present. The presence of fixed mutational differences in mtDNA and in one of the two nDNA markers analysed, the lack of gene flow, and diagnosable morphological differences (including potential display signals) between X. u. udzungwensis and X. u. obscurata, suggest that X. u. obscurata be accorded full species status, Xenoperdix obscurata, for which we put forth the common name ‘Rubeho forest partridge'.

Journal of East African Natural History Vol. 94(1) 2005: 191–201