Behavioral Ecology and Sociobiology

, Volume 49, Issue 4, pp 289–295

Ectoparasite loads in free-ranging northern fence lizards, Sceloporus undulatus hyacinthinus: effects of testosterone and sex

  • Matthew Klukowski
  • Craig E. Nelson
Original article

DOI: 10.1007/s002650000298

Cite this article as:
Klukowski, M. & Nelson, C. Behav Ecol Sociobiol (2001) 49: 289. doi:10.1007/s002650000298


More knowledge of the proximate factors that influence parasite loads would help us understand the selective pressures faced by hosts and host-parasite evolution. Testosterone has been associated with increased parasite loads in vertebrates. Here we asked whether experimentally elevated testosterone affected ectoparasite loads in free-ranging northern fence lizards (Sceloporus undulatus hyacinthinus). Males were captured, given testosterone or sham implants, and released. In 2 consecutive years, testosterone-implanted males had significantly more ectoparasites at recapture than did controls. Additionally, ectoparasite loads were positively correlated with testosterone concentrations in unmanipulated males, and males had significantly more ectoparasites than did females. The results are consistent with an effect of testosterone on parasite loads. However, rather than elevated testosterone increasing mite loads in experimental males, it appeared that high testosterone inhibited a natural seasonal decline in mite loads. Testosterone-implanted males also lost body mass whereas controls gained mass. Among controls, those retaining the most ectoparasites over the course of the experiment experienced the smallest gains in body mass, suggesting that the mites are costly.

Sceloporus undulatus Testosterone Parasites Trombiculid mites Condition 

Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • Matthew Klukowski
    • 1
  • Craig E. Nelson
    • 1
  1. 1.Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USAUSA
  2. 2.Present address: Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132, USA, e-mail:, Tel.: +1-615-9048435, Fax: +1-6158985093USA

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