Morphological variation among populations of the quokka, Setonix brachyurus (Macropodidae : Marsupialia), in Western Australia

Abstract

Variation in five external morphological characters was examined among two island populations and five remnant mainland populations of the quokka, Setonix brachyurus. Sexual dimorphism was observed, with males being significantly larger than females at each location. Pairwise comparisons among populations showed that significant differences were mostly between the two island populations. There was a general trend for animal size to decrease with latitude. Multivariate analyses did not show clear geographic groups, although the island populations tended to cluster. The inheritance of the morphological characters was examined by comparing island populations with those of a captive colony on the mainland, but which originated from the same island. Significant differences between these populations were observed for tail-width measures, suggesting that environmental conditions may be responsible for some variation, but considerable variation may also be due to underlying genetic variation.