Life History Strategies of Female Northern Elephant Seals

Life history theory assumes that organisms cannot maximize survival and fecundity at the same time, because of constraints that may be physiological or ecological. As a result, higher reproductive effort will entail a cost in terms of subsequent survival or future reproductive success or both (Williams 1966; Stearns 1976; Schaffer and Rosenzweig 1977). The concept of a cost of reproduction has led to many studies on the apparent trade-off between current reproductive effort and the probability of future reproductive success (see reviews in Clutton-Brock 1988 and Nur 1990). Studies of marine mammal life history traits in relation to the cost