Meeting Abstract
Male mice produce ultrasonic vocalizations (USV) during sexual encounters and these appear to act as secondary sexual characters. To understand whether these signals convey information about a male’s condition, we handicapped wild-derived house mice (M. musculus domesticus) males by making them experience sickness and then assessed their ability to vocalize. To do this, we housed brother pairs in separate recording chambers connected to a common central chamber by mesh-covered windows. One of the males was injected with lipopolysaccharides (LPS) to induce sickness behaviors, while the other was injected with saline. Both males were then exposed to the same female stimulus and their behaviors and vocalizations were recorded overnight. Before exposure to the female, males in both treatments produced virtually no vocalizations. When presented with a female, mice treated with LPS emitted significantly fewer syllables then the control. Females discriminated between control and LPS-injected males, spending more time with the former. The amount of time females spent close to a certain male could not be explained by the number of syllables emitted by that animal. Finally, we combined this with data on expression of urinary proteins to understand how these might interact with auditory cues in facilitating female choice. Our results suggest that USVs produced by males in the context of courtship may function as an honest signal of current condition, although not necessarily the only signal females use to make their decisions. Our experiment helps understand how animals integrate information from different sensory modalities, similar to that which animals experience in their natural environment.
