Female association preferences based on olfactory cues in the guppy,<Emphasis Type="Italic"> Poecilia reticulata</Emphasis>

Guppies are highly sexually dimorphic. Females have been shown to mate preferentially with males with various visible traits and previous studies investigating mate choice have focussed on these visual cues. However, guppies have been shown to respond behaviourally to odour cues from conspecifics as well as from predators. Therefore, sexual selection in guppies may act on multiple sensory modalities, but so far only visual cues have been investigated. Here, we used a specially designed olfactory choice tank to determine whether females could detect other guppies on the basis of their olfactory cues only, and to determine whether females preferred to associate with males or females and whether they could distinguish between different males. We show that female guppies associated preferentially with other females when given a choice between water containing the odour cues from another fish and water containing no odour cues. When females were presented with olfactory cues from a male and a female, they investigated the female initially, but then most reversed their decision and swam to the male. Furthermore, we demonstrate that females associated preferentially with certain males based upon olfactory cues alone, but that this choice was in direct opposition to that made when the females received only visual cues from the same males.Communicated by: M. Abrahams