Tick Thermal Tolerance Limits Vary Among Populations and Vary Significantly With Altitude and Latitude

Abstract

By Kamryn Fleming, Biological Sciences

Advisor: Joshua Benoit

Presentation ID: 92

Abstract: Understanding what determines the geographic range of species is crucial for predicting the effects of environmental change and especially for vectors that transmit diseases and may influence new host populations as they move to new locations. Winter ticks detrimentally impact moose and are increasing in many regions of the United States and Canada. To test whether environmental temperatures may limit the geographic extent of winter ticks, we measured the thermal tolerance limits of 9 tick populations distributed throughout North America. Tick larvae from gravid females were exposed to hot and cold temperatures and survival was assessed at 24 hours following exposure. We found significant differences in thermal tolerance traits among disparate tick populations. Larval thermal tolerance limits varied significantly with altitude and latitude of collection sites; despite being reared in lab conditions. Altogether, this suggests that winter tick populations may be locally adapted and therefore have uneven responses to environmental change. Our study highlights the importance of measuring physiological traits of several populations when considering the impact of environmental change on a species to account for the influence of local adaption and plasticity.