Sexual Selection's Effects on Male Life History and the Pattern of Male Mortality

Abstract

Modifications of male life history due to sexual selection should be apparent in polygynous species such as elephant seals, in which sexual selection has produced a high degree of sexual dimorphism. In theory, male traits that confer a mating advantage bear survival disadvantage. The aim of this study was to examine the relationship between sexual selection and life history patterns in male northern elephant seals, Mirounga angustirostris. A life table, with age—specific estimates of mortality and reproduction, was constructed for male elephant seals from resighting data of tagged seals. Increased agespecific mortality was associated with the period of first reproduction by males, which occurred from 6—10 yr of age. A negative relationship was found between mating success and future survival in males that were beginning to breed. Older males showed no phenotypic costs to reproduction, and a positive, but not significant, relationship was shown between current mating success and future survival and mating success.