The effects of familiarity and reproductive status on olfactory discrimination by female Cape ground squirrels (Xerus inauris)

Abstract

The ability to differentiate among conspecifics on the basis of genetic relatedness can be advantageous in kin and mate selection. Selection of mates that are of an intermediate degree of relatedness maximizes the propagation of shared genes to offspring, while minimizing the accumulation of deleterious recessive alleles that can result from close inbreeding. Odors produced from various glandular surfaces of the body have been shown to influence discrimination of conspecifics in numerous taxa, including the order Rodentia. We investigated whether female Cape ground squirrels (Xerus inauris) discriminate between the odors of familiar and foreign males by conducting scent experiments. We simultaneously presented odors that had been collected on acrylic cubes from the anal gland of a familiar (non-dispersed) and a foreign male as well as an unscented control, and recorded the response of focal pregnant and non-pregnant females (n = 19). Non-pregnant females responded differently to the odors of the scent cubes, sniffing the scent collected from the foreign male significantly longer than either the familiar male or control odor, whereas there was no difference in the response of pregnant females. We conclude that male familiarity may influence female mate choice, as familiarity is reliably correlated with relatedness in this population. Based on prior knowledge about the social behaviour of Cape ground squirrels, the ability to discriminate between familiar and foreign males may be used by females as an inbreeding avoidance mechanism, as close inbreeding can be avoided by mating with foreign males.