The information content of odour, colour and tactile cues in the mate choice of minnows

Abstract

Sexual displays often involve many different signal components, which may give information about the same or different mate qualities. We studied the information content of different signals in male minnows (Phoxinus phoxinus) and tested whether females are able to discriminate between males when only olfactory cues are present. We found that females preferred the odour of males with a more saturated (i.e., redder) belly, but only when the females had been in physical contact with the males before the experiments. Instead, when unfamiliar males were used, females did not discriminate between male odours and also the overall swimming activity (mate choice intensity) of the females was significantly lower. More ornamented males had lower number of Philometra ovata parasites (indicated by belly saturation) and Neoechinorhynchus rutili parasites (indicated by belly hue) than their less ornamented counterparts. We did not find experimental evidence for female odour preference being linked to belly hue and breeding tubercle number, but in the nature these traits were associated with the condition factor of the males. Taken together, our results suggest that belly colouration and breeding tubercles give honest information on several aspects of male quality. In addition females may learn the association between male colouration and their olfactory signals and utilize this information when visual signals are not present.