Effects of exposures to siblings or sibling odors on sibling recognition in prairie voles (Microtus ochrogaster)

Abstract

Determining the mechanisms of sibling recognition is important for understanding social behavior and the basic parameters of population dynamics (cycles) in microtine rodents. Previous studies have shown that, after relatively short periods of isolation, prairie voles (Microtus ochrogaster) no longer recognize their siblings. In this study we tested the hypothesis that brief encounters of prairie voles with siblings or sibling odors during a period of isolation can maintain social memory and the ability of animals to recognize their siblings over time. Six-week-old voles of both sexes that were isolated for 21 days and exposed (on days 3, 6, 9, 12, 15, and 18 of this 21-day isolation period) to brief encounters (30 min for each encounter) with their siblings continued to recognize their siblings when tested for social interactions at 42 days of age. Only females exposed to odors of same-sex siblings during the period of isolation continued to recognize their sisters. Males exposed to odors of same-sex siblings did not recognize their brothers when tested for social interactions at 42 days of age. These results demonstrate that after dispersal prairie voles need occasional encounters with their siblings, or their siblings' odors (at least in females), to reinforce social memory and the ability to recognize kin over prolonged periods of time. This study is the first to provide empirical evidence that helps us understand the mechanism by which sibling prairie voles, which are philopatric or often settle in home ranges close to one another, almost never form breeding pairs.