Behavioural diversity of an insular population of Tramea darwini, with notes on Brachymesia herbida and Erythemis vesiculosa (Odonata, Libellulidae)

Behavioural diversity is a level of biodiversity that focuses on the existence of alternative behaviours, either linked to different ecological functions or with similar functional significance. Here, we tested whether libellulid dragonflies from species-poor communities of Isabela island (Galapagos) show high diversity in their egg-laying strategies, which is the expectation if the behavioural niche is not completely filled by the relatively few species present in the community. Our results indicate that the community of odonates of these island ponds shows very high diversity of oviposition strategies, with four modes for Tramea darwini (more than any other studied population of the genus) and two for the other common libellulids, Brachymesia herbida and Erythemis vesiculosa. The most frequent oviposition strategy of T. darwini ('tandem-oviposition-tandem') was clearly less efficient than oviposition by females alone or under non-contact guarding, and a similar result was found for B. herbida and E. vesiculosa, whose females were more efficient when alone in comparison to oviposition under male non-contact guarding. We suggest that this paradox is attributable to sexual conflict, which favours a different behaviour in males and females.