We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Competitive females are successful females; phenotype, mechanism, and selection in a common songbird.
- Authors
Cain, Kristal; Ketterson, Ellen
- Abstract
In a variety of taxa, male reproductive success is positively related to the expression of costly traits such as large body size, ornaments, armaments, and aggression. These traits are thought to improve male competitive ability and, thus, access to limited reproductive resources. Females of many species also express competitive traits. However, we know very little about the consequences of individual variation in competitive traits and the mechanisms that regulate their expression in females. Consequently, it is currently unclear whether females express competitive traits owing to direct selection or as an indirect result of selection on males. Here, we examine females of a mildly dimorphic songbird ( Junco hyemalis) to determine whether females show positive covariance in traits (morphology and behavior) that may be important in a competition. We also examine whether trait expression relates either to testosterone (T) in terms of mechanism or to reproductive success in terms of function. We found that larger females were more aggressive and that greater ability to produce T in response to a physiological challenge consisting of a standardized injection of gonadotropin-releasing hormone predicted some measures of female body size and aggression. Finally, we found that aggressive females had greater reproductive success. We conclude that T may influence female phenotype and that females may benefit from expressing a competitive phenotype. We also suggest that the mild dimorphism observed in many species may be due in part to direct selection on females rather than simply a correlated response to selection in males.
- Subjects
SONGBIRDS; LUTEINIZING hormone releasing hormone; DIMORPHISM in animals; TESTOSTERONE; SEXUAL behavior in birds; DARK-eyed junco; PHENOTYPES; PASSERIFORMES
- Publication
Behavioral Ecology & Sociobiology, 2012, Vol 66, Issue 2, p241
- ISSN
0340-5443
- Publication type
Article
- DOI
10.1007/s00265-011-1272-5