The Multitrophic Plant-Herbivore-Parasitoid-Pathogen System: A Biosemiotic Perspective

In the past three decades there has been an increasing number of studies concerned with the effects that alterations in biodiversity may have on ecosystem functioning. In these studies a great emphasis has been on ecological processes such as productivity, energy flow and nutrient cycling. The models for multitrophic interactions and above and below ground interactions furnish a picture based on material exchanges, i.e., trophic webs, between the participating taxa. On the other hand, in most disciplines of biology there is an incipient trend that considers biology as a science of “sensing”, that is, biologists in different sub-disciplines are assigning increasing importance to the informational processes in living systems and are paying more attention to the “context” (e.g., from quorum sensing to info-chemicals to signal transduction in general). There is a new and exciting epistemological path opened in ecology which is seriously considering the evolution of signals as one of the most important processes in ecosystems functioning. There is in the literature a call for integration of molecular and ecological perspectives. But instead we find a tendency to reduce the latter to the former, that is, to decompose (reduce) the ecological complexity into its molecular “components”. The aim of this paper is to present the biosemiotic perspective as a useful conceptual framework to reorganize and interpret the general model for ecosystem functioning (in relation to biodiversity changes) present in many different empirical studies of what we could call the “multitrophic plant–herbivore–parasitoid–pathogen system”.