Climatic and altitudinal influences on variation in macaca limb morphology.

Karen J Weinstein

doi:10.1155/2011/714624

Abstract

This study compares limb lengths and joint diameters in the skeletons of six macaque species (Macaca assamensis, M. fascicularis, M. fuscata, M. mulatta, M. nemestrina, and M. thibetana) from a broad range of habitats and climates in order to test whether ambient temperatures, latitude, and altitude influence interspecific variation in limb morphology in this widely dispersed genus. Analysis of variance, principal component analysis, and partial correlation analysis reveal that species from temperate latitudes and high elevations tend to have short limbs and large joint diameters for their sizes while species from tropical latitudes and low elevations tend to have long limbs and small joint diameters. Interspecific variations in intra- and interlimb length proportions also reflect phylogeny and subtle differences in locomotion. The results of this study suggest that climatic conditions are important factors among many ecological variables that influence limb morphology in this geographically widespread genus.

Highlights

Ecogeographic patterns, such as Bergmann’s and Allen’s rules, have long been of interest to evolutionary biologists testing hypotheses about the evolution of geographic variation within and among closely related species
This study examines whether altitude and latitude and ambient temperature influence interspecific variation in Macaca limb proportions by comparing the skeletons of Assamese (Macaca assamensis), crab-eating (M. fascicularis), Japanese (M. fuscata), rhesus (M. mulatta), pig-tailed (M. nemestrina), and Tibetan macaques (M. thibetana) (Figure 1)
Members of the fascicularis species group have higher intralimb length proportions than pig-tailed, Assamese, and Tibetan macaques, indicating that the length of the tibia is closer to equal to the length of the femur in the fascicularis species group compared with other species

Summary

Introduction

Ecogeographic patterns, such as Bergmann’s and Allen’s rules, have long been of interest to evolutionary biologists testing hypotheses about the evolution of geographic variation within and among closely related species. Macaque species inhabit the greatest geographic range of any nonhuman primate genus from 10◦ South to over 40◦ North latitude, habitats that extend from lowland tropical forests to temperate climates and altitudes in excess of 2500 m, and stretching from Afghanistan eastward through Taiwan and Japan, and a single species in Northwest Africa (Figure 1) Despite this geographic diversity, Macaca is a monophyletic genus comprised of 22 species that Fooden [1, 35] and Delson [2] divide into four species groups based on male reproductive anatomy and which Groves [3] divides slightly differently into six species groups (Table 1). Within Fooden’s fascicularis species group, crab-eating macaques (M. fascicularis) are the most primitive species with other members of this species group, rhesus (M. mulatta), Japanese (M. fuscata), and Taiwanese macaques (M. cyclopis), as descendant populations continuously distributed throughout Southeast and Anatomy Research International

Methods

Results

Discussion

Conclusion