Quantitative analysis of courtship and mating behaviours in the big-headed turtle, Platysternon megacephalum

摘要

Turtles are an excellent group for understanding the theory of sexual selection, sexual dimorphism and the evolution of courtship behaviour. Asia has a rich diversity of turtle species, but quantitative analysis of courtship behaviour has only been conducted on a single species. This study quantitatively analysed courtship and mating behaviours of captive Platysternon megacephalum to serve as a basis for future comparisons with other freshwater turtles. A total of 259 courtship behaviour sequences stemming from 66 pairings between 12 males and 24 females were analysed. Seven (approaching, sniffing, chasing, resting, mounting, subduing female, copulating) and three mutually exclusive motor patterns (fleeing, mating resistance, mating acceptance) were performed by males and females, respectively. The temporal sequences of courtship and mating behaviours were analysed using Chi-square tests and Kappa analyses, from which a flow diagram was constructed. Male courtship display patterns involved tactile, visual and olfactory cues for conspecific and sexual recognition. In response, females may have emitted olfactory cues regarding their sex and reproductive status. Male P. megacephalum exhibited biting, but no head movement or foreclaw display in courtship, which differs from other freshwater turtles. This study provides the first record of male biting during courtship behaviour in an Asian turtle species. Recommendations for captive breeding of the endangered species P. megacephalum are presented.