Effects of testosterone treatment and season on the frequency of dewlap extensions during male-male interactions in the lizard Anolis sagrei

Richard R. Tokarz, Stephen McMann, Linda C. Smith, Henry John-Alder

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Lizards of the genus Anolis extend and retract a large and often brightly colored throat fan called a dewlap. The dewlap in most anoles is a sexually dimorphic structure. It is larger in males than females and males use the dewlap more frequently and in more contexts than do females. In the present study we investigated whether plasma testosterone (T) levels and season affect the frequency of dewlap use in male-male interactions in the brown anole, Anolis sagrei. We manipulated plasma T levels by implanting adult, castrated males with pellets that delivered no T, a moderate dose of T, or a high dose of T. In tests with stimulus males, castrated males that were treated with a moderate or with a high dose of T had a significantly higher frequency of dewlap extensions than did castrated males that received no T. However, the frequency of dewlap extensions in castrated males that received the high dose of T did not differ significantly from castrated males that received the moderate dose of T or from noncastrated control males. Males captured during the breeding season and tested in the laboratory had a significantly higher frequency of dewlap extensions than did males captured in the post-breeding season and tested in the same manner. These results suggest that plasma T levels affect how frequently males of A. sagrei extend their dewlaps in male-male interactions and that seasonal changes in male dewlap use may be due to seasonal differences in plasma T levels.

Original languageEnglish (US)
Pages (from-to)70-79
Number of pages10
JournalHormones and Behavior
Volume41
Issue number1
DOIs
StatePublished - Jan 1 2002

Keywords

  • Androgen
  • Anolis sagrei
  • Dewlaps
  • Lizards
  • Male display behavior
  • Sexually dimorphic traits
  • Testosterone

ASJC Scopus subject areas

  • Endocrinology
  • Behavioral Neuroscience
  • Neurology
  • Psychology(all)

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