The Effects of Cross-Fostering On the Behavior of Two Species of North American Lemmings, Dicrostonyx Groenlandicus and Lemmus Trimucronatus. Iii. Agonistic Behavior

Abstract

Abstract1. The role of the maternal environment in development of species-specific agonistic behavior was investigated by reciprocally cross-fostering two species of lemmings (Discrostonyx groenlandicus and Lemmus trimucronatus). Non-fostered and within-species-fostered (in-fostered) animals served as controls. 2. When adult, cross-fostered male lemmings engaged in more frequent contact social behavior with the foster species than with conspecifics. However, since cross-fostered animals retained their ability to interact with conspecifics in a species-specific manner, cross-fostering appears to have resulted in a broadening of "species identity" to include the foster species. 3. In-fostering reduced the aggressiveness of Dicrostonyx but had little effect on the behavior of Lemmus. 4. Both the intensity and orientation of agonistic behavior were altered as a result of cross-fostering. In Dicrostonyx, a highly aggressive species, cross-fostering resulted in decreased aggression directed at the foster species and increased aggression toward conspecifics. In Lemmus, a less aggressive species, cross-fostering appears to have resulted in a broadening of the response range to stimuli provided by the foster species. When paired with aggressive Dicrostonyx, cross-fostered Lemmus engaged in more frequent and intense aggression than did controls. However, when paired with nonaggressive (in-fostered) Dicrostonyx, cross-fostered Lemmus engaged in less frequent and intense aggression than controls. In contrast, non-fostered and in-fostered Lemmus males had a relatively narrow response range to Dicrostonyx. 5. In general, the results suggested that agonistic behaviour in lemmings is the product of a complex interaction between genotype and maternal environment.