Is <i>Colobus guereza gallarum</i> a valid endemic Ethiopian taxon?

• Main Authors: D. Zinner, D. Tesfaye, N. C. Stenseth, A. Bekele, A. Mekonnen, S. Doeschner, A. Atickem, C. Roos
• Format: Article
• Language: English
• Published: Copernicus Publications 2019-04-01
• Series: Primate Biology
• Online Access: https://www.primate-biol.net/6/7/2019/pb-6-7-2019.pdf

<p>Black-and-white colobus (<i>Colobus guereza</i> Rüppell, 1835) are arboreal Old World monkeys inhabiting large parts of the deciduous and evergreen forests of sub-Saharan Africa. Two of the eight subspecies of <i>Colobus guereza</i> are endemic to Ethiopia: <i>C. g. gallarum</i> and <i>C. g. guereza</i>. However, the validity of the Ethiopian taxa is debated and observed morphological differences were attributed to clinal variation within <i>C. g. guereza</i>. To date, no molecular phylogeny of the Ethiopian guerezas is available to facilitate their taxonomic classification. We used mitochondrial DNA markers from 94 samples collected across Ethiopia to reconstruct a phylogeny of respective mitochondrial lineages. In our phylogenetic reconstruction, augmented by orthologous sequence information of non-Ethiopian black-and-white colobus from GenBank, we found two major Ethiopian mitochondrial clades, with one being largely congruent with the distribution of <i>C. g. guereza</i>. The second clade was found only at two locations in the eastern part of the putative range of <i>C. g. gallarum</i>. This second lineage clustered with the lowland form, <i>C. g. occidentalis</i>, from central Africa, whereas the <i>C. g. guereza</i> lineages clustered with <i>C. g. caudatus</i> and <i>C. g. kikuyuensis</i> from Kenya and northern Tanzania. These two guereza lineages diverged around 0.7&thinsp;million years ago. In addition, mitochondrial sequence information does not support unequivocally a distinction of <i>C. g. caudatus</i> and <i>C. g. kikuyuensis</i>. Our findings indicate a previous biogeographic connection between the ranges of <i>C. g. occidentalis</i> and <i>C. g. gallarum</i> and a possible secondary invasion of Ethiopia by members of the <i>C. g. guereza</i>–<i>C. g. caudatus</i>–<i>C. g. kikuyuensis</i> clade. Given these phylogenetic relationships, our study supports the two-taxa hypothesis, making <i>C. g. gallarum</i> an Ethiopian endemic, and, in combination with the taxon's very restricted range, makes it one of the most endangered subspecies of black-and-white colobus.</p>