Reversible frequency-dependent switches in male mate choice

Current sexual-selection theories predict that mating should occur preferen tially with the highest-quality partner, and assume that for distinguishing among potential mates the choosy sex applies an internal representation of the characteristics of the desired mate, i.e. a template. Binary choice ex periments were performed to test male mate choice between two different fem ale colour morphs in the damselfly Ischnura elegans. Choice experiments wer e conducted before and after an habituation period, during which males were exposed to only one female colour morph. Given the choice between the two female morphs, males did exhibit a choice for the most recently experienced female morph. This is the first evidence for a reversible switch in mate c hoice in a frequency-dependent way. In contrast with previous studies on ma te choice, template formation in male I. elegans seems not to be based on q uality Switching mate choice in a frequency-dependent manner, choosing the most common morph, probably allows males to minimize their search efforts a nd to maximize fitness.