Mate choice in experimentally parasitized rock doves: Lousy males lose

Abstract

A recent model by Hamilton and Zuk (1982) suggests that exaggerated secondary sexual traits facilitate mate choice for genetic resistance to parasites. The model predicts that individuals discriminate against parasitized mates by scrutinizing traits indicative of parasite load. In the case of birds and their feather-feeding lice, for example, individuals might avoid parasitized mates bydetecting reduced plumage brightness, reduced courtship display, or increased grooming. I conducted a series of mate choice trials in which female Rock Doves (Columba livia) were allowed to choose between "clean" males without lice and "lousy" males with experimentally increased loads. Clean males displayed significantly more often than lousy males and females demonstrated a significant preference for clean males. Lousy males were subject to plumage damage; however, none of the damage was externally visible, and the time spent grooming by clean and lousy males did not differ significantly. Female louse loads, which were also manipulated, were not significantly related to female mating preferences. These results are consistent with the Hamilton-Zuk model. They are also consistent with a model of sexual selection for the avoidance of parasite transmission, which is discussed. The general relevance of lice and other ectoparasites to models of parasite-mediated sexual selection is reviewed. © 1990 by the American Society of Zoologists.