Intraspecific variation in ungulate mating strategies: the case of the flexible fallow deer.

Abstract

Over the past three decades, rapid advances in evolutionary theory in combination with increasingly sophisticated field studies have led to greater understanding of the functional significance of reproductive behavior. There is now a general concensus that male mating strategies are influenced by the spatial and temporal distribution of receptive females, which are in turn affected by variation in resource distribution, predation pressure, the costs of social living, and the activities of other males (Jarman, 1974; Emlen and Oring, 1977; Clutton-Brock and Harvey, 1978; Wrangham and Rubenstein, 1986; Clutton-Brock, 1989; Davies, 1991). Mating systems are now seen as the outcome of the reproductive strategies of individuals rather than the evolved characteristics of species. Variation in mating strategies is expected both within and between populations as a consequence of the adaptive adjustment of individual behavior to differences in the social and ecological environment (Rubenstein, 1980; Dunbar, 1982; Clutton-Brock, 1989; Davies, 1991; Lott, 1984, 1991).
Intraspecific variation in mating strategies among the ungulates received much attention during this time with realization of the great flexibility of reproductive behavior in many species. In no single species was this more marked than for the fallow deer Dama dama on which research on mating strategies intensified during the late 1980s with the recognition that some populations of fallow deer breed on leks - aggregations of small, clustered male territories visited by females primarily to mate (Schaal, 1986, 1987; Putman, 1986; Pemberton and Balmford, 1987; Clutton-Brock et al., 1988; Apollonio, 1989; Langbein and Thirgood, 1989). Leks have aroused intense interest from behavioral ecologists in recent years because they offer unusual opportunities to investigate aspects of female mate choice, sexual selection, and the evolution of mating systems (Balmford, 1991; Wiley, 1991; Hoglund and Alatalo, 1995).
The aim of this chapter is to reassess the evolution of alternative mating strategies in fallow deer in the light of the research of the past decade. First, we present a conceptual framework for understanding the diversity of fallow deer mating strategies and explore the ecological background to this variation. Second, we review recent attempts to assess the costs and benefits to male and female fallow deer of adopting different mating strategies. Throughout, we consider the broader implications of these studies on fallow deer for a general theory of the evolution of ungulate mating systems.