Kin Recognition in Ground Squirrels and Other Rodents

Significant advances have been made in understanding kin recognition as it pertains to nepotism (preferential treatment of kin) and mate choice (optimization of inbreeding and outbreeding). Yet complementary knowledge about how animals discriminate conspecifics on the basis of genetic relatedness remains unclear for most species. Because of the diversity of their scent sources and highly developed olfactory systems, rodents present a unique opportunity for examining chemical communication and kin recognition as a function of sociality. I review general processes of kin recognition and summarize mechanisms of recognition used by rodents. As a case study, I also examine recognition systems of ground squirrels, relating odor production and perception to differences in patterns of nepotism. Belding’s ground squirrels (Spermophilus beldingi) produce $2 odors (from oral and dorsal glands) that correlate with relatedness (kin labels), and they are able to use these odors to make precise discriminations among their unfamiliar relatives. Thus, S. beldingi can recognize their distant female kin and male kin, even though these kin are not treated nepotistically (e.g., through cooperative territory defense or alarm call production). Furthermore, S. beldingi use these kin labels and recognition abilities to interact differentially with conspecifics as a function of relatedness. In ground squirrels and in other rodents, components of the kin recognition process (production of recognition cues, discrimination of these cues, and differential treatment of conspecifics) have evolved differentially among even closely related species. Kin recognition abilities in the absence of nepotism might reflect selection for inbreeding avoidance mechanisms, in addition to sex-biased natal dispersal. Together, data and the review demonstrate that recognition abilities cannot be predicted on the basis of sociality alone and suggest that comparative analyses, by multiple assays of discrimination, might be necessary to understand variation in the function of kin recognition within and across species.