Mitochondrial diversity and distribution of African green monkeys (chlorocebus gray, 1870)

Abstract

African green monkeys (Chlorocebus) represent a widely distributed and morphologically diverse primate genus in sub-Saharan Africa. Little attention has been paid to their genetic diversity and phylogeny. Based on morphological data, six species are currently recognized, but their taxonomy remains disputed. Here, we aim to characterize the mitochondrial (mt) DNA diversity, biogeography and phylogeny of African green monkeys. We analyzed the complete mitochondrial cytochrome b gene of 126 samples using feces from wild individuals and material from zoo and museum specimens with clear geographical provenance, including several type specimens. We found evidence for nine major mtDNA clades that reflect geographic distributions rather than taxa, implying that the mtDNA diversity of African green monkeys does not conform to existing taxonomic classifications. Phylogenetic relationships among clades could not be resolved suggesting a rapid early divergence of lineages. Several discordances between mtDNA and phenotype indicate that hybridization may have occurred in contact zones among species, including the threatened Bale monkey (Chlorocebus djamdjamensis). Our results provide both valuable data on African green monkeys' genetic diversity and evolution and a basis for further molecular studies on this genus.

Fig. 1

Distribution of African green monkeys (Chlorocebus) and collection sites of fecal and museum (bold) samples. Species distributions are shaded and modified from Lernould (1988) and Kingdon (1997). Colored symbols indicate phenotypes determined. Numbers correspond to IDs in Fig. 2 and Supporting Information Table SI. IDs of type specimens are boxed. Schematic drawings depicting main differences in facial characters are redrawn from Hill (1966).

Fig. 2

Bayesian phylogram with posterior probabilities and ML bootstrap support values based on the complete cyt b gene. C1/I-C9/VII indicate main mtDNA clades. Bootstrap support values of >90% and posterior probabilities of >0.98 are presented as black dots; values below are given at respective nodes. Type specimens are boxed.

Fig. 3

(A) Median-joining network of mtDNA sequences with depicted clade affiliations (see Fig. 2). Sizes of circles indicate haplotype frequencies and colors represent different phenotypes. Black dots along branches represent median vectors and branch length is relative to the number of mutated positions. (B) Map showing geographic distribution of the mtDNA clades detected. Samples indicating discordance between mtDNA and observed phenotype are highlighted with black dots. Question marks indicate recommended regions for future studies.