Introduction

The detailed analysis of breeding success of many individuals over entire lifetimes has proved extremely illuminating for our understanding of natural selection and population dynamics, for example in Soay sheep (Chapter 3), in red deer (Albon et al. 2000; Clutton-Brock et al. 2002) and in many other species (see studies reported in Clutton-Brock 1988a; Newton 1989). In general, however, this literature is dominated by data on female reproductive success, which, due to the prevalence of maternal care, relatively easy to collect accurately. In polygynous mating systems, parallel studies of male breeding success are particularly important. First, information on lifetime breeding success tells us how natural and sexual selection shape the strategies males employ to obtain fertilisations. Second, if selection on males leads to heavy energy investment at particular life stages or times of year which make males more likely to die than females, then an understanding of selection contributes directly to our understanding of population dynamics. Finally, if selection on males sets up conflicts of interest between males and females that results in selection on females, knowledge of such conflicts refines our understanding of female reproductive strategies and dynamics.

Prior to 1990, relatively few studies had reported on male lifetime breeding success within polygynous vertebrate breeding systems, and data were based exclusively on observed mating success; examples include red deer (Clutton-Brock et al. 1988a), elephant seals (Le Boeuf and Reiter 1988), lions (Packer et al. 1988), vervet monkeys (Cheney et al. 1988) and savannah baboons (Altmann et al. 1988).