Objectives
Direct comparative work in morphology and growth on widely dispersed
wild primate taxa is rarely accomplished, yet critical to understanding
ecogeographic variation, plastic local variation in response to human
impacts, and variation in patterns of growth and sexual dimorphism. We
investigated population variation in morphology and growth in response to
geographic variables (i.e., latitude, altitude), climatic variables (i.e.,
temperature and rainfall), and human impacts in the vervet monkey
(Chlorocebus spp.).
Methods
We trapped over 1600 wild vervets from across Sub-Saharan Africa and
the Caribbean, and compared measurements of body mass, body length, and
relative thigh, leg, and foot length in four well-represented geographic
samples: Ethiopia, Kenya, South Africa, and St. Kitts & Nevis.
Results
We found significant variation in body mass and length consistent
with Bergmann’s Rule in adult females, and in adult males when
excluding the St. Kitts & Nevis population, which was more sexually
dimorphic. Contrary to Rensch’s Rule, although the South African
population had the largest average body size, it was the least dimorphic.
There was significant, although very small, variation in all limb segments
in support for Allen’s Rule. Females in high human impact areas were
heavier than those with moderate exposures, while those in low human impact
areas were lighter; human impacts had no effect on males.
Conclusions
Vervet monkeys appear to have adapted to local climate as predicted
by Bergmann’s and, less consistently, Allen’s Rule, while
also responding in predicted ways to human impacts. To better understand
deviations from predicted patterns will require further comparative work in
vervets.