Geographic Variation in Savanna Baboon (Papio) Ecology and its Taxonomic and Evolutionary Implications

Abstract

Jolly (1993) stated that the degree of ecological niche separation among closely related taxa may help to distinguish their evolutionary relationships since ecological divergence is often thought of as a characteristic of true biological species. Based on qualitative data, Jolly (1993) hypothesized that there is little niche separation among savanna baboon forms and therefore suggested that they are a single species. In addition, a recent study by Frost and colleagues (2003) found that baboon cranial morphology covaried with latitude that also suggests a single species designation. This present study quantitatively examined the ecological niche space of savanna baboons to test Jolly’s hypothesis and to examine how their ecological variation varied with geography. To investigate this idea, previously published long-term data were accumulated from over twenty savanna baboon populations. Variables from four categories were used to quantify their niche space: 1) Environment, 2) Diet, 3) Activity budget, and 4) Social organization. A discriminant function and principal components analysis was conducted for each dataset, and confirmed that savanna baboon subspecies inhabit significantly distinct environments, yet display a statistically non-significant difference in their diet, activity budget, and social organization. In addition, a hierarchical cluster analysis revealed that savanna baboon ecology followed a latitudinal cline. Therefore, the results of these analyses cannot falsify Jolly’s hypothesis that there is little ecological niche separation among baboon taxa.