Territory inheritance and the evolution of group-living in carnivores

Abstract

The Territory Inheritance Hypothesis (TIH) on the evolution of group-living in carnivores considers (1) the increased fitness of the original territory holders when they ensure that the territory will be inherited by a carrier of their own genes, and (2) the increased fitness of a subadult that remains at home and survives in an otherwise saturated environment. A comparison of the fitness of both adults and subadults (at different rates of population growth and adult survival) who either do or do not choose the strategy of building up a group, indicates that groups are favoured in decreasing to slightly increasing populations at moderate to high (>0.5) annual rates of adult survival. Furthermore, an analysis of maximum group size under the TIH suggests that groups of five or more adults should split up. The TIH as an explanation for group-living in the red fox, Vulpes vulpes L., and the badger, Meles meles L., is compared with the Resource Dispersion Hypothesis (RDH, Macdonald 1983) and the Constant Territory Size Hypothesis (CTSH, von Schantz 1984a), which consider spatio-temporal fluctuations in food supply. The RDH is the best explanation of social organization in the badger; the RDH and the CTSH both explain red fox data under special conditions, but are not satisfactory as general explanations of group-living in this species; the TIH may explain why group-living, at least once it is established, is a stable strategy.