Species Richness of Parasite Assemblages: Evolution and Patterns

Abstract

Parasite communities are arranged into hierarchical levels of organization, covering various spatial and temporal scales. These range from all parasites within an individual host to all parasites exploiting a host species across its geographic range. This arrangement provides an opportunity for the study of patterns and structuring processes operating at different scales. Across the parasite faunas of various host species, several species-area relationships have been published, emphasizing the key role of factors such as host size or host geographical range in determining parasite species richness. When corrections are made for unequal sampling effort or phylogenetic influences, however, the strength of these relationships is greatly reduced, casting a doubt over their validity. Component parasite communities, or the parasites found in a host population, are subsets of the parasite fauna of the host species. They often form saturated communities, such that their richness is not always a reflection of that of the entire parasite fauna. The species richness of component communities is instead influenced by the local availability of parasite species and their probability of colonization. At the lowest level, infracommunities in individual hosts are subsets of the species occurring in the component community. Generally, their structure does not differ from that expected from a random assembly of available species, although comparisons with precise null models are still few. Overall studies of parasite communities suggest that the action of processes determining species richness of parasite assemblages becomes less detectable as focus shifts from parasite faunas to infracommunities.

Endophytic bacterial communities in the periderm of potato tubers and their potential to improve resistance to soil‐borne plant pathogens

“…In community ecology, differentiation between a random assemblage of organisms and a structured community is based on the presence of statistical associations among community members (Poulin, 1997). Sturz & Matheson (1996) showed that, when examined as communities, endophytic bacteria within potato tubers affected resistance to bacterial soft rot (Erwinia carotovora var.…”

Metazoan parasite species richness and genetic variation among freshwater fish species: cause or consequence?

“…Data points represent phylogenetically independent contrasts. richness in ®sh and other vertebrates, but ®sh body size is the most pervasive covariate among these [22,37]. We eliminated several ®sh species from our data set because they had been investigated at fewer than 20 loci and estimates of their genetic variability may have been imprecise [18,19].…”

Structure in parasite component communities in wild rodents: predictability, stability, associations and interactions .... or pure randomness?

“…Within each region are parasite component communities of that host, comprising metapopulations of individual parasite species that circulate among the host metapopulation in a definable ecosystem, perhaps discreet woods, fields or other types of habitats. At the lowest level we have infracommunities which comprise infrapopulations of all the species encountered within an individual animal, and which are therefore in closest contact with one another (Poulin, 1997(Poulin, , 2004. It is interactions between infrapopulations within infracommunities, repeatedly observed in different component communities, that we seek to identify, but first I will outline some general patterns of parasite infra-and component-community structure in rodents, using data on helminths in bank voles.…”