> CASES OF GENETIC RELATEDNESS

In Belding's ground squirrels (Spermophilus beldingi), which inhabit mountain meadows in the western U.S., costly helping appears in the alarm calls of sentinels watching for predators. Unlike meerkats, Belding's ground squirrels that raise an alarm are more frequently preyed upon. In this case, the ground squirrels in one area tend to be closely related. They alert — and benefit — mostly their kin. Relatedness among individuals varies, however, and underlies significant differences in calling behavior. Males tend to disperse from their place of birth, while females remain local. Females thus have more kin neighbors than males do and, accordingly, they devote more time to the sentinel role. In addition, their alarm calls are more numerous when only close relatives are nearby. While alarm calls in general seem to have evolved based on foraging in the open during the day, the pattern and frequency of sentinel risks in the Belding's ground squirrels seems to reflect kin selection (Sherman 1977; Shelley and Blumstein 2004).