Ectoparasites of small mammals: Interactive saturated and unsaturated communities

Introduction: Parasites of different species often co-occur on a host individual or host population forming a community. Spatial distribution of parasite communities is fragmented among host individuals, among host species within a location, and among locations. To distinguish between scales, a hierarchical terminology has been proposed (Esch et al., 1990; Combes, 2001; Poulin, 2007). In this chapter, I will refer to an assemblage of parasites of all species infesting an individual host as an infracommunity, to an assemblage of parasites of all species infesting a host population as a component community and to an assemblage of parasites of all species infesting a host community as a compound community. There are at least two principal differences between infracommunities and communities at higher hierarchical levels. First, the former are short-living by definition, while the latter persist much longer. Second, parasite species in infracommunities may exert selective pressures on each other, which then induce the selection of traits that limit competition by separating niches (Holmes & Price, 1986). In contrast, interspecific interactions in component and compound communities are less likely. It is thus not surprising that studies of parasite community structure were focused mainly on infracommunities, while component and compound communities have received less attention.