February 15 2011

12:00 BSRB 154

This seminar is sponsored by Dept. of Ecology and Evolutionary Biology

Ecolunch: Julien Martin
Dept. of Ecology and Evolutionary Biology

Selfishness and conservatism in the Rockies: the reproductive strategies of bighorn ewes


Life history theory suggests an energetic trade-off between physiological cost of maintenance and reproduction. In long-lived species in temperate climates, this trade-off could be measured as energy allocation to fat reserve and body condition versus allocation to lactation and offspring growth. When resource availability is variable, instead of a fixed energy allocation to reproduction based on average conditions, natural selection should favor an adjustment of effort based on individual body condition and on resource availability at each reproductive event. My main research interest is to study the variation in energy allocation to reproduction, i.e. reproductive strategies, in highly variable environments. My research is based on a long-term project on bighorn sheep that has involved tagging and weighing individual sheep at Ram Mountain, Alberta, since1972. Bighorn sheep are long-lived mountain ungulates with a strong sexual dimorphism. Ewes can reproduce at two years and give birth to one young every year until they die. Using summer mass changes of mother-lamb pairs to estimate reproductive effort, I have estimated how reproductive effort vary according to both maternal and environmental conditions. Two major points arise from all analyses: a strong and ubiquitous inter-individual variation and a conservative strategy of reproduction of ewes, which favor their own maintenance and survival over the growth of their lambs.















































































































































































































































































































































































































































































































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