The demographic basis of population regulation in columbian ground squirrels.

Kin selection in Columbian ground squirrels (Urocitellus columbianus): littermate kin provide individual fitness benefits.

Since W. D. Hamilton's seminal work on the evolution of sociality, a large body of research has accumulated on how kin selection might explain the evolution of cooperation in many group-living species. Our study examined the evolutionary basis of philopatry and cooperation; specifically, whether individuals benefit from the presence of close kin. We applied an individual fitness approach to a 1...

Managing anabolic steroids in pre-hibernating Arctic ground squirrels: obtaining their benefits and avoiding their costs.

Androgens have benefits, such as promoting muscle growth, but also significant costs, including suppression of immune function. In many species, these trade-offs in androgen action are reflected in regulated androgen production, which is typically highest only in reproductive males. However, all non-reproductive Arctic ground squirrels, irrespective of age and sex, have high levels of androgens...

Parasite removal and its impact on litter size and body condition in Columbian ground squirrels (Spermophilus columbianus).

The current interest in studies of parasite-host relationships is focusing on the impact of parasites on mate choice, sexual selection and individual fitness. While most studies have been done on birds and fishes, little is known about the interactions between parasites and reproductive success in mammals. In this study, I experimentally removed ectoparasites (mainly fleas) from some female Col...

The relative importance of global and local landmarks in navigation by Columbian ground squirrels (Spermophilus columbianus).

In order to survive, small burrowing mammals need to remember the locations of escape burrows. Therefore, it is important to know what types of landmarks are used to aid navigation in the wild. The author tested the ability of free-ranging Columbian ground squirrels (Spermophilus columbianus) to locate escape burrows when local (e.g., vegetation pattern, local relief), global (e.g., forest edge...

Testing the reproductive and somatic trade-off in female Columbian ground squirrels