Abstract

Body form and function of animal species have been shaped over time in response to prevailing local conditions that affect survival and reproduction. Morphological variation in size and shape thus occurs within-species across eco-geographic regions. Different theories have been proposed to explain this variation. For example, Bergmann’s rule posits that intra-species body size increases positively with latitude and negatively with temperature. Alternatively, the resource rule suggests that the quantity and quality of available resources is the primary determinant of body shape and size. Here, we used photogrammetry to quantify morphological variation among wild dogs (Lycaon pictus) across eight African countries within three regions (western, eastern and southern), using the skeletal ratio of shoulder height to body length. We found that morphological variation was explained mostly by country and region, with latitude also being an influential predictor. Wild dogs in eastern Africa (Kenya and Tanzania) had the lowest measured skeletal ratio while the western population especially in Senegal had the highest. The effect of latitude, although not strongly linear, suggests some support for Bergmann’s rule. However, variations in latitude are associated with changes in other environmental conditions that directly influence resource availability. This makes the resource rule a better theory to explain morphological variation among wild dogs. Nevertheless, these findings indicate phenotypic plasticity among wild dog populations which can be taken as basis for rigorous genetic comparisons. Also, these remaining populations should all be conserved regardless of current size and movement between them should occur naturally without translocation especially for populations which are phenotypically distinct. 

Keywords

Bergmann's rule, Photogrammetry, Lycaon pictus resource rule, Shoulder height.

Received on 16/04/2017, Accepted on 01/06/2017, Published on 26/06/2017