“Ours is a world of sights and sounds. We live by our eyes and ears and tend generally to be oblivious to the chemical happenings in our surrounds. Such happenings are ubiquitous. All organisms engender chemical signals, and all, in their respective ways, respond to the chemical emissions of others. The result is a vast communicative interplay, fundamental to the fabric of life” (Eisner and Meinwald 1995, p. v), cited under General Overviews). Chemical ecology is the study of ecological interactions between organisms mediated by chemicals produced by those organisms. Chemical interactions between organisms can be analyzed across all organizational levels, reaching from cell-cell interaction and intraspecific and multitrophic-level interactions to whole community interactions and environmental ecological processes. Because of their ubiquity, chemical signals that carry information (semiochemicals) can be categorized by the types of ecological interactions they mediate, such as intraspecific social communication, antagonistic interactions, and mutualism. Accordingly, this article is organized into three core areas, one formed by the chemicals mediating interactions between members of the same species (pheromones), and the others by interspecific interactions involving allomones (where the sender benefits), and synomones (where both sender and receivers benefit). A fourth group of signals, kairomones (where the receiver benefits), can comprise all other signal categories when they are perceived and utilized by a third organism that itself gains a benefit from eavesdropping on communication between others. While primary studies in chemical ecology focused on the identification of compounds mediating interactions between organisms, today’s debates are dominated by micro- and macroevolutionary aspects of chemical interactions. The very rapid growth of the chemical ecology literature over recent decades has been, in part, driven by the growing appreciation of the high economic value of understanding chemical communication, reaching from applications in pest management over the control of disease vectors in agriculture to the use of chemical signals in medicine. Moreover, the field has dramatically profited from innovations in analytical chemistry, making the separation of complex compound mixtures as well as the identification of compound structures efficient and accessible to a broader community of researchers. Recent advances in molecular ecology have aided an even more rapid mechanistic and functional analysis of semiochemicals, leading to a modern consolidation of different research fields. This collection of significant publications focuses on the functional and evolutionary analysis of chemical signals important in mediating ecological interactions. Moreover, attention has been given to publications that provide conceptual frameworks and are among the most highly cited in the respective subdisciplines. They can thus provide a good introduction for the interested reader and allow efficient forward and backward searching for more detailed information.
The Chemical Ecology of Elephants: 21st Century Additions to Our Understanding and Future Outlooks
