PARENT SESSION
Session #10: Functional similarity and functional groups in ecological systems. Organized by: P. Morin and R. Zamora.
Tuesday, August 7, 2001. Lecture Hall
Ecological and Evolutionary consequences of functional equivalence in ecological interactions.
Zamora, Regino1, Gómez, Jose M.2, 1 2
ABSTRACT- Most of the interactive systems known are multispecifics, often an animal interacting with many plant species and viceversa. From the standpoint of the functioning of these interactive assemblages, a main question is whether changes in taxonomic identity of the interacting species affect the outcomes of the interactions. Functional equivalence between two or more interactive organisms occurs when they bring about the same effect on the host species. This may appear in the qualitative and/or quantitative aspects of ecological interactions. Populations of different species can generate similar frequencies of occurrence of the interaction by having, for example, similar population abundance and/or frequency of visits. On the other hand, different species, by sharing similar qualitative traits, can exert similar per capita effects on the fitness or the population size of a target species. Pairwise specialization is possible only when different species bring about different interactive outcomes. By contrast when very different interactive species have the same effect on host-species fitness, they can constitute a single selective pressure, the evolutionary process presumably resulting in this case in a more generalized response to whole groups of species interacting in a similar way. Functional equivalence promotes generalization in ecological systems, allowing consistency in both pressures and responses to selection in ecological and evolutionary arenas. Functional equivalence can stabilize ecological communities, since a change in interactive organisms may have no effect in the functioning of whole system.
KEY WORDS: multispecific systems, generalization, Functional equivalence