RAPID EVOLUTIONARY RESPONSE TO RESOURCE PULSES AND CLIMATE IN A NORTHERN MAMMAL

We have been studying the ecology of red squirrels in the southwestern Yukon for over twenty years. Red squirrels feed on seed from spruce trees and spruce trees exhibit masting behaviour whereby massive cone crops tend to be synchronized over large areas.  Consequently squirrels face huge changes in resource levels and this important selective agent drives changes in life history characteristics such as timing of reproduction, litter size, and juvenile growth rates.  I will outline how we are able to track phenotypic and evolutionary changes in the populations we study as they experience changes in climate and food supply.