The effect of temperature and behaviour on the interaction between two dragonfly larvae species within the native and expanded range

Abstract

Studies on interaction between species are needed to observe and predict the effects of climate change on species distributions. Here we studied intra- and interspecific competition and behaviour in larvae of a native and a northward expanding dragonfly species, Sympetrum vulgatum and Sympetrum fonscolombii, respectively. We estimated growth, mortality, and behaviour (prey capture success, activity, and boldness) at 20°C and 23°C. The northward expanding S. fonscolombii had a higher growth rate and a higher survival compared with the native S. vulgatum in interspecific competition. In intraspecific conditions, there was no significant difference between species in mortality and growth. Temperature had no significant effect on growth and survival of S. fonscolombii, but S. vulgatum showed both a higher growth rate and a higher mortality at 23°C under intraspecific conditions. There was a correlation between growth and mortality, suggesting that cannibalism and intraguild predation caused the growth differences between treatments in the competition experiments. Temperature had no significant effect on any of the behaviours. There were very few significant correlations between any of the behaviours and the life-history traits survival and growth and there were also very few significant correlations between any of the behaviours. Repeatability of behaviours over ontogeny was low. The results of the present study suggest that the range expanding S. fonscolombii has the potential to outcompete the native species, but that this competition advantage does not seem to be driven by the temperature effects explored in this study.