Androgen control of social status in males of a wild population of stoplight parrotfish, Sparisoma viride (Scaridae).
In the protogynous stoplight parrotfish (Sparisoma viride), large males defend territories that encompass the home-ranges of several mature females. However, high-quality habitat is in short supply, such that smaller, competitively inferior males do not defend territories. We investigated the role of 11-ketotestosterone (11KT) and testosterone (T) in the regulation of territorial behavior in a wild population of a protogynous reef fish, the stoplight parrotfish, at Glover's Reef, Belize. Radioimmunoassay of plasma samples from individuals of known social status revealed that nonterritorial males have lower levels of T and 11KT than territorial males. Nonterritorial males allowed access to vacant territories underwent pronounced increases in T and 11KT. When sampled 1 week after territory acquisition, levels of T and 11KT in new territorial males were significantly higher than the levels in established territorial males, but by 3 weeks after territory acquisition, there was no significant difference. We further investigated the hypothesis that such short-term increases in androgen levels are a response to intense male-male interactions during territory establishment. Simulated territorial intrusion promoted increased plasma levels of both T and 11KT while access to vacant territories without neighboring territorial males did not. These findings suggest that the endocrine system plays a role in fine-tuning the levels of territorial aggression exhibited by male stoplight parrotfish. We discuss these results in light of recent theory in behavioral endocrinology.
Cardwell
J R
JR
Department of Zoology, University of British Columbia, Vancouver, Canada.
Liley
N R
NR
D000728:Androgens / Q000502:physiology*; D000818:Animals; D004291:Dominance-Subordination; D005399:Fishes / Q000502:physiology*; D006702:Homing Behavior; D012726:Sexual Behavior, Animal / Q000502:physiology*; D012931:Social Environment; D013731:Territoriality; D013739:Testosterone / Q000031:analogs & derivatives / Q000502:physiology
D000728:Androgens; D013739:Testosterone; C003600:11-ketotestosterone