D3078: Expression of ion-gated channels and population differentiation in cold tolerance of bumble bees (genus Bombus)

For many insects, thermal tolerance is a key determinant of both spatial distribution and fitness and therefore often varies with local climate. Recent work has revealed striking differences in cold tolerance among bumble bee populations – bees from high elevations enter chill coma at temperatures ~6-8 °C colder than bees from nearby low elevations. These differences persist for bees reared in common garden conditions, suggesting local adaptation in cold tolerance. Paired transcriptomics experiments suggest that variation in expression of several key proteins may play a role in these population differences in bumble bee cold tolerance. One key protein that varied strongly in expression across populations in response to cold is Shal, which is known to regulate the potassium permeability of neural membranes and may therefore play an important role in maintenance of ion homeostasis critical for avoiding chill coma. We compared baseline Shal expression and expression in response to cold exposure for bumble bees reared in common garden conditions from queens collected at high and low elevations. We discuss the potential importance of this protein in cold tolerance variation and local adaptation for bumble bees.