FLUCTUATING TRADE-OFFS FAVOR PRECOCIAL MATURITY IN MALE SOAY SHEEP

Although trade-offs between reproductive effort and survival are commo nly proposed, empirical studies that quantify the true costs and benef its of breeding activity are rare. This information is crucial, howeve r, for examining the adaptive value of important life history traits s uch as age at maturity. Here we estimate both the survival cost, and g enetic benefits, of precocial male maturity in a highly polygynous nat urally limited population of Soay sheep. While we demonstrate that ear ly reproduction does indeed carry a survival cost, we find that young males also achieve unexpectedly high reproductive success and that pre cocial mating is favoured due to the fluctuating demographic structure of the population.