Testosterone slows wound healing, independent of body condition, in equatorial Rufous-collared Sparrows


Meeting Abstract

P2.38  Wednesday, Jan. 5  Testosterone slows wound healing, independent of body condition, in equatorial Rufous-collared Sparrows MOORE, Ignacio T*; SMALL, Thomas W; Virginia Tech; University of Memphis itmoore@vt.edu

Testosterone has been implicated as an important mediator of trade-offs between the reproductive and immune systems. However, this has not been well tested in tropical species with very different life histories than northern temperate species. Unlike other Zonotrichia sp., Rufous-collared Sparrows in Ecuador do not elevate testosterone in response to territorial challenges and do not appear to use testosterone to regulate aggressive behaviors in a traditional manner. This modified association between testosterone and aggressive behaviors could be a strategy to avoid the costs of extended periods of elevated testosterone. Here we test the hypothesis that elevated testosterone inhibits wound healing, independent of body condition, in male Rufous-collared Sparrows. Captive male sparrows from Ecuador were given either testosterone or blank implants. Each hormone treatment group was then further divided into two groups, one provided either a mixed seed diet, which causes weight gain, the other provided a plain grass seed diet, which maintains normal weight, for the duration of the experiment. All individuals received a small tissue biopsy on the flank opposite their implant. Biopsy sites were photographed on day 0, day 6 and day 8. Area and perimeter of biopsies were measured on the images to asses healing rate. Testosterone treatment slowed healing rate but diet had no effect. These data suggest that elevated testosterone inhibits healing rate independent of body condition in this species. Thus it appears that male Rufous-collared Sparrows may not respond to territorial challenges by elevating testosterone to avoid this potential cost of the hormone.

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