Katie Brooks

Katie Brooks is broadly interested in the evolution of social systems. Particularly, she is interested in understanding why some species live in groups and some do not. Theoretically, group living should evolve if the fitness benefits outweigh the costs. Costs to group living may include increased vulnerability to disease or competition for resources and mates. Benefits, on the other hand, may include reduced predation risk, increased fitness or increased foraging efficiency. In any social species, many factors probably promoted the evolution of group living. However, most studies evaluate only one or two hypotheses, without regard for competing explanations.

In her dissertation research, Katie is investigating multiple mechanisms for why sociality evolved and is maintained in the Belding's ground squirrel, Urocitellus beldingi. Belding's ground squirrels are a diurnal species that live in large populations consisting of female kin groups and unrelated males. Close female relatives interact nepotistically through alarm calling and group territory defense. Katie studies Belding's ground squirrels at the Mateo Lab field site near Mammoth Lakes, CA. At this alpine meadow site, the U. beldingi population is active between April and August and hibernates the remainder of the year.

Katie will test whether the nepotistic relationships among female kin provide physiological benefits, such as lower cortisol levels or increased immune function, or fitness benefits. If so, kin selection may have played a role in the evolution of this social system. She will also examine vigilance behavior to test whether U. beldingi experience lowered predation risk through group living. Finally, Katie will complete a phylogenetic analysis of social system evolution within the Marmotini, a tribe within the squirrel family comprised of ground squirrels, marmots and prairie dogs. She will examine the plasticity and direction of social system evolution and whether social system evolution is correlated with environmental characteristics. When her research is completed, Katie will have a better understanding of the adaptive value of U. beldingi sociality.