Climate change is predicted to make cold-blooded animals hotter and have higher energy demands. Our research published earlier this year suggests the energetic costs of climate warming for cold-blooded animals may be underestimated if we do not account for species interactions.
A while back, Vanessa Kellermann and I conducted an experiment to study the effect of species interactions on the metabolic rate of fruit flies (Drosophila) reared at different temperatures that represent current and future climates along the east coast of Australia. To do this, we reared the larvae of three Drosophila species in single-species or two-species cultures with limited food to promote competition.
After adult flies emerged from our cultures, we measured the metabolic rate and activity of nearly 400 adult female flies using a multi-channel flow-through respirometry system and Drosophila activity monitors.
We discovered that when the larvae of two species interacted at warmer temperatures, they were more active as adults, and consequently had higher metabolic rates, compared to those that did not develop with another species.
Using our experimental results, we modelled the metabolic responses of adult flies under an intermediate climate-warming scenario across the global range of Drosophila to gain insight into the energetic costs of climate warming for flies with and without species interactions. Our model simulations show that we risk underestimating the energy needs of ectotherms in a warming world by 3–16% if we fail to account for interactions between species.
But in agreement with a previous study, we found that physiological acclimation to warmer temperatures can reduce the energetic cost of climate warming from 39% to ~16%. Unfortunately, however, our results suggest that species interactions may erode the energetic gains of physiological acclimation by causing adult flies that develop at warmer temperatures to expend more energy on activity.
To read more about this research, check out our article in The Conversation and the News & Views article in Nature Climate Change written by Dr Mathieu Videlier.