Meeting Abstract
Climate change is expected to shift species distribution as populations grow in favorable habitats and decline in harsh ones. For montane animals, the ability to escape hot, dry conditions at low elevation may be limited by low oxygen availability at high elevation. The willow beetle Chrysomela aeneicollis lives along steep elevation gradients (2400-3600 m) in the Sierra Nevada mountains of California and populations are sensitive to climate- they are found at low elevation following wet winters and retreat to high elevation during drought. Beetles living at high elevation have higher mitochondrial concentrations and develop more slowly than those found at low elevation. In these populations, mitochondrial Cytochrome c Oxidase II varies with latitude to a much greater extent than many other genes, one form predominating in the north (COII-1), another in the south (COII-2). To examine the role this genetic variation plays in effects of elevation on performance, we collected hatchlings from populations where frequency of northern and southern COII is equal and reared them under common garden conditions in the laboratory at high and low elevation. We found that larvae possessing COII-2 developed equally well at high and low elevation, while COII-1 larvae developed much slower at high elevation. Once larvae reached the 3rd instar, running speed was measured before and after heat treatment. Larvae reared at low (but not high) elevation ran slower after heat treatment, and the effect was greater for individuals possessing COII-1. These data suggest that low oxygen may limit growth and performance of a small insect, and that elevations just above beetles’ current range may reduce performance of individuals possessing “northern” mitochondria.
