PARENT SESSION
Poster Session 25: Mammalian Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Senescence in a Red Squirrel population.

Descamps, Sébastien^{*,1, 2}, Berteaux, Dominique¹, Gaillard, Jean-Michel², Boutin, Stan³, ¹ Canada Research Chair in Conservation of Northern Ecosystems, Rimouski, Québec, Canada² Université Claude Bernard Lyon I, Lyon, France³ Department of Biological Sciences, Edmonton, Alberta, Canada

ABSTRACT- In vertebrate populations, individual fitness is expected to decrease with age because of senescence. Very few studies have investigated senescence in rodents although they represent more than 40% of the mammalian species. In order to fill the gap, we analysed long-term data collected on a North American Red Squirrel population using robust statistical methods to assess the influence of age on fitness components. We found strong evidence of senescence in females. The survival (from five years of age onwards) and the probability to breed successfully (from six years of age onwards) decreased with increasing age. In addition, the probability of having weaned juveniles surviving until one year old decreased for old mothers. This represents the first evidence of a long term effect of senescence in a vertebrate population. Whether senescence occurred in male life history was not so clear. Male survival may decrease from seven years of age onwards but no data were available to test for senescence in reproduction.

Key words: senescence; capture-mark-recapture; non linear mixed models; red squirrel