Meeting Abstract

P2.28  Sunday, Jan. 5 15:30  Variation in nuclear and mitochondrial genes important for energy metabolism along a climatic gradient in montane populations of a leaf beetle ROBERTS, KT*; HEIDL, SJ; ZAVALA, NA; MARDULYN, PM; SMILEY, JT; DAHLHOFF, EP; RANK, NE; Sonoma State University; SSU; Santa Clara University; Free University of Brussels; SCU; SSU roberkev@seawolf.sonoma.edu

Montane organisms live in small, fragmented populations that are vulnerable to climate change, and the ability of these populations to persist depends on whether they possess genetic variation in their capacity to respond and adapt to altered environments. In the Sierra Nevada Mountains of California, the willow leaf beetle Chrysomela aeneicollis occurs at high elevations just below tree line (2400-3600 m). Genetic variation at 12 loci was examined along a 75 km transect from the King’s River in the southwestern Sierra to Rock Creek in the Eastern Sierra, a cline that corresponds to a latitudinal temperature gradient. Genetic divergence was 10-fold greater at the enzyme locus phosphoglucose isomerase (PGI) and the mitochondrial gene cytochrome oxidase II (COII) than at 10 other loci. PGI and COII alleles that predominate in the south are replaced by ‘northern’ alleles in Rock Creek, supporting the hypothesis that these genes are directly or indirectly under selection. In prior studies, we describe functional, physiological, and reproductive differences among PGI genotypes. Here we show that COII haplotype and PGI genotype interact to affect adult running speed, female reproductive success and larval development rate in the face of natural and laboratory manipulated thermal variation. We also found that cytochrome oxidase enzyme activity varies among PGI genotypes. Taken together, these data suggest that natural selection may act jointly on COII and PGI. Thus, genetic variability at mitochondrial and nuclear loci critical for energy metabolism may contribute to population persistence in the face of rapid environmental change.