title: Effects of isolation on sibling recognition in prairie voles, Microtus ochrogaster.
abstract: Traditionally, sibling recognition in prairie voles has been inferred by incest avoidance or lack of reproduction among littermates. Previous studies have shown that isolation of sibling prairie voles for 8-15 days causes the breakdown of incest avoidance. However, in a re-evaluation of these studies, using social interactions within sexes (amicable versus agonistic behaviours), rather than incest avoidance, we found that incest avoidance might not be the best criterion for inferring sibling recognition in this species. When sibling prairie voles were isolated for less than 20 days, same-sex siblings still showed evidence of recognition in social encounter tests. Only after 20 days of isolation did sibling prairie voles show low levels of amicable behaviours and very high levels of agonistic behaviours; therefore, treating their siblings in the same way that they treated nonsiblings. Sibling recognition should be seen as a continuum, which can be inferred and detected experimentally at different time intervals by different approaches (incest avoidance or social interactions). Our results help to elucidate the effects of isolation on sibling recognition and help to determine the possible mechanisms responsible for the maintenance of social memory for recognition cues after periods of isolation. Copyright 1999 The Association for the Study of Animal Behaviour.