Interference interactions, co-existence and conservation of mammalian carnivores

Warder C. Allee brought attention to the possibility of a positive relationship between aspects of fitness and population size 50 years ago. Until recently, however, this concept was generally regarded as an intriguing but relatively unimportant aspect of population ecology. Increasing appreciation that Allee effects must be incorporated into models of population dynamics and habitat use, together with recent interest in the implications of sociality for conservation, have shown that for ecology and conservation the consequences of the Allee effect are profound. The Allee effect can be regarded not only as a suite of problems associated with rarity, but also as the basis of animal sociality.

There is a long-standing debate in ecology concerning the relative importance of competition and predation in determining community structure. Recently, a novel twist has been added with the growing recognition that potentially competing species are often engaged in predator-prey interactions. This blend of competition and predation is called intraguild predation (IGP). The study of IGP will lead to a reconsideration of many classical topics, such as niche shifts, species exclusion and cascading interactions in food webs. Theoretical models suggest that a variety of alternative stable states are likely in IGP systems, and that intermediate predators should tend to be superior in exploitative competition. Many field studies support these expectations. IGP is also important in applied ecological problems, such as the conservation of endangered species and fisheries management. Copyright © 1992. Published by Elsevier Ltd.