Conclusiones

Chemical ecology aims at analyzing the intra- and inter-specific interac-tions between organisms and their environment at the molecular level of chemical substances synthesized by them. By definition, the field is

∗Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, Im Neuenheimer feld 364, 69120 Heidelberg, Germany.

†Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany.

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interdisciplinary in scope and includes both chemical and biological research. Chemical investigations of the compounds produced by organ-isms include studies of structure, biosynthesis, organic synthesis, and mechanisms of action, while biological studies focus on the ecological con-sequences of these phenomena.

The chemistry of terrestrial plants and insects has been studied for the past century, and tens of thousands of different natural products have been isolated and chemically defined. This chemical knowledge of terres-trial organisms has contributed greatly to the development of the field of chemical ecology over the past few decades. Chemists have realized that molecules that they isolate and characterize often have potent biological activities and have likely evolved for specific biological functions. Subse-quently, biologists and ecologists have realized that chemical substances, particularly the secondary metabolites, play an important role in com-plex behavioral and ecological interactions among organisms. The field has advanced most rapidly as the result of collaboration among chemists and biologists, including the incorporation of results and ideas from chemical research into biological research, and vice versa.

Research on terrestrial chemical ecology has provided a great deal of basic information that has advanced the fields of organic chemistry, bio-chemistry, ecology, behavior, and evolution. In addition, many practical applications have also developed. Knowledge of plant-insect interactions mediated by defensive compounds and other secondary metabolites has been used to create applications or the control of insect pests and micro-bial diseases in crop plants. Much of the pharmaceutical industry is based on terrestrial natural products or compounds modeled after these natural products.

So far, several thousand marine natural products have been chemi-cally defined; many of which are biologichemi-cally active compounds possessing novel functional groups and molecular structures.¹⁻³Interest in biotech-nological applications for marine natural products has increased over the past decade, as the knowledge of the chemistry of marine organisms has developed. Applied studies have identified applications of these compounds as pharmaceuticals. Moreover, preliminary evidence suggests that marine organisms also provide an untapped resource for future biotechnological applications. Several marine natural products have already been approved

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for the treatment of cancer and pain and many others are currently being evaluated in clinical trials in the United States and in Europe for the treat-ment of various cancers.⁴In contrast to terrestrial studies, however, much less is known about the natural functions of these metabolites in the marine environment. Only in the past few years have experimental evaluations been conducted to shed light on the role of marine natural products in the lives of the organisms that produce them.

Studies in marine chemical ecology have increased quantitatively and qualitatively in the last few decades and this has fueled a rapid development of the field. The main reasons for that were the identification of groups of marine plants and animals that are especially rich in secondary metabolites as well as the technological advances in the isolation and characterization of chemical compounds. Interest in marine chemical ecology developed as the knowledge of numerous and diverse natural products found in marine organisms increased. Marine natural product chemists began to ask ques-tions about how the compounds they isolated function in nature. Early experiments addressed the antibiotic, antifungal, and ichthyotoxic effects of these metabolites, but not all of them used marine microorganisms or marine fish to test the hypothesis that these compounds were toxic and deterrent to predators and pathogens. The ecological context of these metabolites and the marine organisms that produce them is now being considered and experiments are more carefully designed and replicated for statistical analysis. For instance, naturally co-occurring predatory fishes and pathogenic microorganisms are now being used to test the deterrent effects of compounds from marine organisms. Progress in experimental design and analysis of these types of bioassays has been made in the past years, especially as marine ecologists have become more interested in chemical ecology.⁵

Manipulative field studies are now common in both terrestrial and marine ecology. In many experiments, competitors or predators are either added to or excluded from a habitat to understand their influence on com-munity structure. Similarly, secondary metabolites can be added to artificial diets and tested as feeding deterrents against natural herbivores or predators in field studies.⁶

The increasing interest in collaborative studies between marine chemists and ecologists has contributed to the development of a new

generation of marine chemical ecologists. These individuals incorporate advances from both marine biology and natural products chemistry into their research. As a result of this collaboration, marine biologists and chemists were able to explore the marine environment and could observe ecological phenomena. Thus, more sophisticated research targets came under study with the realization that many observed intra- and inter-specific phenomena might have a molecular basis. Since these molecu-lar basis are involved in all life processes, chemical ecology can justifiably include a large variety of topics (i.e. biochemistry, digestive physiology, biogeochemistry, etc.) making it impossible to include all of them in one chapter.