Development of ornamental characters exposed to directional selection
may be particularly sensitive to the effect of parasitic infections. A
ntlers are ornamental characters of importance in intraspecific intera
ctions, and are in reindeer (Rangifer) developed by both males and fem
ales. By antihelmintic treatment of naturally infected female reindeer
we show that parasite intensities affect development of antler asymme
try, but not antler length. These results suggest that asymmetry in an
tlers may reflect parasite intensities and thus be of importance in in
traspecific assessment of genetic resistance towards infectious organi
sms.