| Description |
Male-biased parasitism, where males are more commonly infected with and have higher parasite loads, is common across vertebrate taxa. Several factors could be driving this pattern. The immunocompetence handicap hypothesis suggests that higher testosterone levels in males suppress immune function which in turn decreases the ability of males to resist parasites. Simultaneously, testosterone increases the expression of sexually selected traits, which may indicate a higher baseline resistance to parasitism in quality mates. Other hypotheses tie male-biased parasitism to characteristics of species with polygynous mating systems, including size dimorphism and larger male ranges that may increase exposure to parasites. Here we examine records of parasites of the deer mouse (Peromyscus maniculatus), a widespread polygynous mammal, captured in Utah during the years 2014-2016 to determine if male-biased parasitism occurs in this rodent species. Parasites were separated into ectoparasites (fleas, lice and ticks, all of which were blood feeders) and nematodes (a group of internal parasites) for analyses. Ectoparasite prevalence was significantly higher in male deer mice. Nematode prevalence was not significantly different between sexes. There were no significant differences in mean parasite intensity between female and male deer mice, for either ectoparasites or nematodes, which may be related to the lack of modulation of the deer mouse immune system by testosterone. There was no significant correlation between mass and parasite intensity for either group of parasites. |
