Climate Change Drives Adaptation
Species respond to environmental change in three different ways, says Melanie Hopkins, curator and chair of the Division of Paleontology at the American Museum of Natural History. “They either move to some place where the environment's better, they adapt to the environment, or they go extinct.” When there is nowhere to go, and the environment is changing faster than evolution can keep up, extinction may be inevitable.

However, in some cases, the opposite is happening — evolution is happening too fast. Lauren Buckley is one of the scientists taking a close look at the role of climate change in creating evolutionary mismatch. Buckley studies evolution and ecology at the University of Washington in Seattle. “For a long time, there was an assumption that organisms wouldn't be able to evolve fast enough for some of these shifting environmental pressures,” she says. But her research suggests that in some cases, evolution is potentially moving too fast.

Abstract
How does recent climate warming and climate variability alter fitness, phenotypic selection and evolution in natural populations?

We combine biophysical, demographic and evolutionary models with recent climate data to address this question for the subalpine and alpine butterfly, Colias meadii, in the southern Rocky Mountains.

We focus on predicting patterns of selection and evolution for a key thermoregulatory trait, melanin (solar absorptivity) on the posterior ventral hindwings, which affects patterns of body temperature, flight activity, adult and egg survival, and reproductive success in Colias.

Both mean annual summer temperatures and thermal variability within summers have increased during the past 60 years at subalpine and alpine sites.

At the subalpine site, predicted directional selection on wing absorptivity has shifted from generally positive (favouring increased wing melanin) to generally negative during the past 60 years, but there is substantial variation among years in the predicted magnitude and direction of selection and the optimal absorptivity.

The predicted magnitude of directional selection at the alpine site declined during the past 60 years and varies substantially among years, but selection has generally been positive at this site.

Predicted evolutionary responses to mean climate warming at the subalpine site since 1980 is small, because of the variability in selection and asymmetry of the fitness function. At both sites, the predicted effects of adaptive evolution on mean population fitness are much smaller than the fluctuations in mean fitness due to climate variability among years. Our analyses suggest that variation in climate within and among years may strongly limit evolutionary responses of ectotherms to mean climate warming in these habitats.