The effect of temperature on the interaction between larvae of a native and a range expanding dragonfly species

Climate change might affect the distribution of species; therefore, it is important to anticipate the imminent impact of climate change. Even though climate responses have the potential to affect species interactions, most models on the effect of climate change on species distribution assume that species respond to climate individually. Hence studies on competition effects are needed. In this study, I estimated growth, mortality, and behaviour (prey capture success, activity, exploration and boldness) at 20° C and 23° C at intra- and interspecific competition conditions in larvae of a native and a northward dispersing dragonfly. The results showed that the northward expanding Sympetrum fonscolombii had a higher growth and survival rate compared to the native Sympetrum vulgatum at interspecific conditions. At intraspecific conditions the results showed that temperature had no significant effect on the performance of S. fonscolombii, but S. vulgatum showed both a higher growth rate and a higher mortality at 23 ° C. A significant difference between temperatures within prey capture success rate was found in S. vulgatum only, during the second observation period. There was a correlation between activity and exploration in both species, between prey capture success rate and activity during the third observation round in S. vulgatum, and between prey capture success rate and boldness during the first observation round in S. fonscolombii. No other behaviours were correlated. Prey capture success rate was shown to be repeatable in both species, while boldness was repeatable in S. vulgatum only. The behavioural results suggests that behavioural traits are relatively plastic over ontogeny in both species, possibly caused by behavioural variation within each instar. Additionally, boldness, but not activity and exploration, might aid S. fonscolombii in their northward expansion. The majority of these results were similar at both temperatures and indicate that S. fonscolombii has a higher capacity to tolerate climate change, and their presence might negatively impact the performance of S. vulgatum