Chemoreception and mating behaviour of a tropical Australian skink

In many reptile groups, molecular systematics is currently revealing high levels of cryptic diversity (i.e. genetically distinct lineages that are difficult to distinguish morphologically). One obvious mode for mate discrimination in these cryptic species is chemoreception. We hypothesise that diversity in these groups is not cryptic for pheromones, and mate recognition via chemoreception may be the primary reproductive isolating mechanism. Here, we present a preliminary study of chemoreception in Lampropholis coggeri, a rainforest skink of north-eastern Australia. We first describe the mating behaviour of captive pairs, showing that tongue-flicking is an important component for both males and females, and find that L. coggeri mate more readily when paired with a conspecific from their own population vs. from a nearby population. Based on the assumption that tongue-flicking represents the lizard’s interest, we then experimentally tested scent discrimination using lizard-swabbed cotton buds presented to captive individuals. We found both sexes tongue-flicked more to conspecific scent than to unscented controls. Males tongue-flicked more to female scent than to male scent but did not discriminate between mated and unmated females. While females showed greater interest in conspecific scent, they showed no greater interest in scent from males than females. This lack of discrimination was true for both mated and unmated females. Unexpectedly, however, mated females tongue-flicked substantially more than unmated females. Finally, males tended to tongue flick more often to female scents from their own population than to a nearby population that is moderately genetically divergent. Our results suggest that chemoreception plays a role in mate recognition in this species. Further work should extend to establishing mate recognition between the highly divergent cryptic lineages within this species and the pheromones underlying mate recognition