Long-Term Changes of Heart Rate in Tree Shrews: Indicators of Social Stress?

Abstract

Tree shrews (Tupaia belangeri) are small, diurnal mammals about the size of small squirrels and are found throughout Southeast Asia. Originally considered primates, it now seems likely that they are a model of the common ancestor of all living placental animals (Martin 1968). In nature they live in pairs in territories which they defend vigorously against intruders of the same sex (Kawamichi and Kawamichi 1979). This dominance behavior can also be induced in the laboratory by simply putting two animals of the same sex into one enclosure (von Holst 1972, 1977; von Holst et al. 1983). Furthermore, tree shrews are — in contrast to most other laboratory animals — closely related to primates and strictly diurnal like humans. Thus tree shrews are an interesting animal model for studies of social stress in humans.