Meeting Abstract
The population dynamics of snowshoe hares (Lepus americanus) are fundamental to the ecosystem dynamics of the North American boreal forest, an ecosystem that covers more than half of Canada’s land mass. During their 8-11 year population cycle, hare densities can fluctuate up to 40-fold. The cycle is driven by predators (lynx, coyotes, great-horned owls) that affect hare demography not only through direct mortality but also through non-consumptive effects on reproduction and survival that are mediated by chronic stress. In addition to individual effects, predator-induced stress during pregnancy can act through the mother on her developing offspring, creating the potential for large-scale population effects if all individuals in the population are similarly affected. We investigated the prenatal effects of predation risk during pregnancy in two ways. First, by experimentally increasing predator encounters in an “unstressed” natural population of hares (increase phase, low predator density) using targeted chases of radio-collared pregnant hares by a mammalian predator (domestic dog). Second, by observing change as function of the natural increase in predator density that occurred from the increase to the peak phases of the hare cycle. We found a suite of coordinated gene expression changes in the brains of offspring born to prenatally-stressed mothers. Transcriptional activity of corticosteroid receptor and co-chaperone genes involved in regulating HPA axis function produced a stress-sensitive, neuroresilient offspring phenotype, that could confer early-life survival advantages in an increasingly predator-abundant world.
