Introduction

Numerous ecological studies have investigated how key factors such as resource availability and predation may influence the population dynamics of European ungulates (Clutton-Brock et al.,1985; Putman et al., 1996; Sæther, 1997; Forchhammer et al., 1998; Gaillard et al., 1998, 2000; Jędrzejewska and Jędrzejewski, 1998; Coulson et al., 2006). In comparison, research on the consequences of pathogen infection on ungulate population dynamics has been rather limited. In recent years interest in pathogen–host dynamics has increased not only among ecologists, in relation to these dynamics at a population level, but also among scientists in other disciplines such as veterinarians, immunologists and geneticists whose interests focus on the individual, cellular or genetic level.

As we will discuss, pathogen–host dynamics are complex and involve interconnected ecological, behavioural, physiological and genetic pathways. Because of this complexity it is often difficult to unravel these pathways, which is necessary to gain an understanding of the role of pathogens in shaping the population dynamics of ungulates. As the studies discussed in this chapter demonstrate, long-term research is necessary to reveal the role of pathogens on ungulate population dynamics. Unfortunately this requirement does not conform well to the current short-term nature of research funding.