Intrapopulation Morphological Variation in Introduced African Clawed Frog, Xenopus laevis (Amphibia: Anura: Pipidae) in Japan

Abstract

Abstract: The African clawed frog Xenopus laevis is a largely aquatic frog occurring from central to southern Africa. This species has been used as experimental animal, and has been introduced in many countries including Japan. However, despite its importance as an experimental animal and invasive alien species across the world, but there are few studies on basic biology of X. laevis including individual variation. In this study, we investigated individual variation in external morphology and allometric patterns. Traits not directly related to the skeleton showed high variability, but ecologically important traits like eye size at the youngest stage, showed low variability. No significant external left-right differences were identified. Allometric analysis showed that males have larger heads and eyes than females, suggesting male-male combat during breeding. Male forelimb suggests also showed a faster growth rate, suggesting that longer forelimbs are advantageous for males in breeding.