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A comparison of the subspecific divergence of two sympatric African monkeys, Papio hamadryas & Chlorocebus aethiops: morphology, environment, diet & phylogeny

Dunn, Jason


Jason Dunn


Sarah Elton


The baboon and vervet monkey exhibit numerous similarities in geographic range, ecology and social structure, and both exhibit extensive subspecific variation corresponding to geotypic forms. This thesis compares these two subspecific radiations, using skull morphology to characterise the two taxa, and attempts to determine if the two have been shaped by similar selective forces.

The baboon exhibits clinal variation corresponding to decreasing size from Central to East Africa, like the vervet. However West African baboons are small, unlike the vervet. Much of the shape variation in baboons is size-related. Controlling for this reveals a north-south pattern of shape change corresponding to phylogenetic history. There are significant differences between the chacma and olive baboon subspecies in the proportion of subterranean foods in the diet. No dietary differences were detected between vervet subspecies. Baboon dietary variation was found to covary significantly with skull variation. However, no biomechanical adaptation was detected, suggesting morphological constraint owing to the recent divergence between subspecies. Phylogeny correlates with morphology to reveal an axis between northern and southern taxa in baboons. In vervets C. a. sabaeus is the most morphologically divergent, which with other evidence, suggests a West African origin and radiation east and south, in contrast with a baboon origin in southern Africa. Path analyses of all the factors discussed revealed markedly different relationships between the two taxa, with baboons responding to the environment via diet rather than directly.

The two subspecific radiations have different relationships with diet, environment and phylogeny. In spite of superficial similarities, the study taxa are sufficiently different that similar ecological and environmental selective forces have not produced convergent patterns of radiations. The baboon exhibits greater flexibility and larger size freeing it from limiting constraints faced by vervets. Additionally the two have distinct sites of origins and patterns of dispersals adding a stochastic element to the differences between radiations.


Dunn, J. (2011). A comparison of the subspecific divergence of two sympatric African monkeys, Papio hamadryas & Chlorocebus aethiops: morphology, environment, diet & phylogeny. (Thesis). Hull York Medical School, the University of Hull and the University of York. Retrieved from

Thesis Type Thesis
Deposit Date Nov 20, 2012
Publicly Available Date Feb 22, 2023
Keywords Medicine
Public URL
Additional Information Hull York Medical School, The University of Hull
Award Date Sep 1, 2011


Thesis (7.5 Mb)

Copyright Statement
© 2011 Dunn, Jason. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

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