@article {COX:April 2007:0269-8463:327,
	author = "COX, ROBERT M.",
	author = "JOHN-ALDER, HENRY B.",
	title = "Increased mite parasitism as a cost of testosterone in male striped plateau lizards Sceloporus virgatus",
	journal = "Functional Ecology",
	volume = "21",
	year = "April 2007",
	abstract = "Summary <P></P>&#8226; <P></P>Testosterone (T) co-ordinates the seasonal and sex-specific expression of numerous physiological, behavioural and morphological traits that contribute to male reproductive success. However, increased susceptibility to parasitism has been proposed as a potential cost of elevated plasma T. <P></P>&#8226; <P></P>During the spring breeding season, male striped plateau lizards <I>Sceloporus virgatus</I> harbour significantly more ectoparasitic mite larvae (Acari: Trombiculidae) than females. Plasma T levels are also elevated in males at this time, suggesting that sex differences in mite parasitism may be driven by underlying sex differences in circulating T. <P></P>&#8226; <P></P>We tested this hypothesis experimentally by manipulating plasma T levels of yearling males via surgical castration and exogenous T implants. Upon recapture of free-living animals, we found significantly fewer mites on castrated males relative to either intact controls or castrated males that received T implants. <P></P>&#8226; <P></P>After removing variance attributable to treatment effects, we observed (1) a positive correlation between residual measures of plasma T and mite load, and (2) a negative correlation between residual measures of mite load and growth rate. These correlations suggest a growth cost associated with mite parasitism. <P></P>&#8226; <P></P>Previous studies have shown that exogenous T increases parasitism, but ours is one of the few to show that castration also reduces parasitism. This result, coupled with the fact that our induced plasma T levels remain within physiological limits, makes this one of the clearest demonstrations of a functional relationship between T and parasitism in any free-living vertebrate. <P></P><I>Functional Ecology</I> (2007) <B>21</B>, 327-334 <P></P>doi: 10.1111/j.1365-2435.2007.01251.x",
	pages = "327-334(8)",
	url = "http://www.ingentaconnect.com/content/bsc/fecol/2007/00000021/00000002/art00017"
	doi = "doi:10.1111/j.1365-2435.2007.01251.x"
}