Little is known about the mechanisms of maternal investment that affect offspring fitness in communal groups. This study is the first to evaluate specific mechanisms of investment that affect the fitness of offspring in communal groups. My objectives are to: (1) evaluate dam- offspring discrimination in a communal rodent, (2) determine if communal nesting improves offspring growth even when food is restricted, (3) determine the relative importance of tactile stimulation, warmth and dams milk provided in communal groups on offspring growth, and (4) monitor the survival and reproduction of offspring reared by communal and solitary dams. I found that prairie vole dams treat conspecific newborns but not conspecific weanlings as own. Also, offspring in single-dam groups grow more than offspring reared by solitary dams when food is provided ad-lib. I will test the effect of simulated tactile stimulation and warmth provided by an additional female on offspring growth and dams milk (Expt. 3). I will monitor survival and reproduction of offspring from single-dam groups and solitary dams in outdoor enclosures (Expt. 4). By integrating proximate and ultimate levels of analysis, I will improve our understanding of the evolution of communal nesting. Undergraduates have and will continue be involved in this study.
