Variation at the SDH Gene to Heat Tolerance

The Sierra Nevada montane leaf beetles, Chrysomela aeneicollis, live their lives at high elevations and primarily spend their time dormant in an overwintering stage until the snow melts. Among the environmental factors experienced by the beetles are limited oxygen supply, harsh terrain, and large temperature fluctuation. During the summer months when these beetles are active, temperatures can range from 37C during the day, to -6C at night. In order for these beetles to acclimate to rapid shifts in temperature, there must be some form of evolutionary pressure for their metabolic processes to function efficiently. I mapped one such gene, succinate dehydrogenase (SDH), which we have hypothesized to be involved with running speed efficiency after heat treatment. Running speed of 205 larvae was measured before and after a heat exposure to assess recovery from thermal stress. Larvae from three drainages in the Sierra Nevada mountains were tested (Rock Creek, Bishop Creek, and Big Pine Creek, and we found that SDH frequencies vary greatly among the drainages. Eighty percent of these polymorphisms were related to recovery of running speed after stress.