A study by Caroline Williams and Brent Sinclair of the University of Western Ontario, together with the Hellmann lab, was just published in PLoS One. The paper reports our findings that winter warming negatively affects overwintering butterflies by increasing their metabolism during the months when they are supposed to be resting. Interestingly, we found that some populations of the Propertius duskywing butterfly were better able than others to tune down their metabolism under warmer conditions, partially compensating for the energy drain of warmer conditions.
This paper has several important things to say about the response of species to climate change:
1) Warming during the winter can cause energy drain in insects that reduces their overall fitness and therefore can cause population declines. These effects can occur when a species is not active and combines with climate effects in other parts of the year.
2) Many organisms can partly adjust to climate change by changing physiologically. Figuring out how much they can adjust is a critical to predicting species' responses to climate change.
2) Populations within a single species respond differently to climate change. We should not assume that all parts of a species react to climate change in the same way, yet most of our current models do exactly that. Ecological models of climate change should allow for population differences and include physiological mechanisms such as the effects of temperature on metabolism, survivorship, and reproduction.
These factors matter to human management of biodiversity under climate change--or adaptation of species and ecosystems. It means that we will need to consider population differences when designing management strategies, and we cannot treat a species as if it were the same everywhere across its range. If we were to move species to new locations, for example, we should consider which populations are most appropriate for relocation (or several). Physiological tolerances for climate change also question whether or how much adaptation is needed in the first place. We should not assume that species have no adjustment capacity of their own; instead, we need to measure it.
Click here to see the press release that UWO wrote about our paper.
Click here to see the paper itself.