Info

prevalence of infection increased with body mass, and that sex differences in prevalence were correlated with sexual dimorphism and male-biased mortality (Moore and Wilson 2002).

Within single host species, few field studies have focused directly on links between body mass and parasitism. In chacma baboons (Papio ursinus), Pettifer (1984) used body mass as a proxy variable for age and suggested that prevalence and intensity increased with age for several helminth species (Table 3.2). In nonprimates, Halvorsen (1986) found that larger-bodied male reindeer were more likely to harbor intestinal parasites (results were non-significant for females). However, body mass was again used as a proxy variable for dominance rank, thus emphasizing the need to control for multiple, potentially confounding variables when testing predictions involving age and body mass.

3.3.1.2 Effects of age

Within host species, age effects on infection probability have been examined in a number of field studies (Table 3.2). In yellow baboons (Papio cynocephalus), for example, Hausfater and Watson (1976) found that adult males shed more eggs of intestinal parasites than subadult males, and another study of baboons found higher levels of schistosome infections in adult than immature animals (Miller 1960).

Table 3.2 Effects of body mass or age on parasitism

Host

Parasites examined

Effect of age or body mass

Reference

Across species

Plasmodium

Body mass: positive association, but this result became non-

Davies et al. 1991; Nunn

(Neotropical primates)

(prevalence)

significant after controlling for phylogeny.

and Heymann 2005

Across species

Helminth species

Body mass: positive association, but this result became non-

Vitone et al. 2004

(69 anthropoid

richness

significant after controlling for phylogeny.

Was this article helpful?

0 0

Post a comment