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Bigger groups have fewer parasites and similar cortisol levels: a multi‐group analysis in red colobus monkeys
Author(s) -
Snaith Tamaini V.,
Chapman Colin A.,
Rothman Jessica M.,
Wasserman Michael D.
Publication year - 2008
Publication title -
american journal of primatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.988
H-Index - 81
eISSN - 1098-2345
pISSN - 0275-2565
DOI - 10.1002/ajp.20601
Subject(s) - biology , intraspecific competition , parasite hosting , transmission (telecommunications) , primate , intestinal parasite , competition (biology) , limiting , feces , parasitism , ecology , zoology , demography , helminths , host (biology) , sociology , mechanical engineering , world wide web , computer science , electrical engineering , engineering
If stress and disease impose fitness costs, and if those costs vary as a function of group size, then stress and disease should exert selection pressures on group size. We assessed the relationships between group size, stress, and parasite infections across nine groups of red colobus monkeys ( Procolobus rufomitratus ) in Kibale National Park, Uganda. We used fecal cortisol as a measure of physiological stress and examined fecal samples to assess the prevalence and intensity of gastrointestinal helminth infections. We also examined the effect of behaviors that could potentially reduce parasite transmission (e.g., increasing group spread and reducing social interactions). We found that cortisol was not significantly related to group size, but parasite prevalence was negatively related to group size and group spread. The observed increase in group spread could have reduced the rate of parasite transmission in larger groups; however, it is not clear whether this was a density‐dependent behavioral counter‐strategy to infection or a response to food competition that also reduced parasite transmission. The results do not support the suggestion that gastrointestinal parasitism or stress directly imposed group‐size‐related fitness costs, and we cannot conclude that they are among the mechanisms limiting group size in red colobus monkeys. Am. J. Primatol. 70:1072–1080, 2008. © 2008 Wiley–Liss, Inc.