Insect ecology can be approached using a hierarchical model (Coulson and Crossley 1987). Ecosystem conditions represent the environment (i.e., the combination of physical conditions, interacting species, and availability of resources) that determine survival and reproduction by individual insects, but in turn, insect activities alter vegetation cover, soil properties, community organization, etc. (see Fig. 1.2). A hierarchical approach offers a means of integrating evolutionary and ecosystem approaches to studying insect ecology. The evolutionary approach focuses at lower levels of resolution (individual, population, community) and offers explanation (i.e., natural selection) for individual and population adaptation to environmental conditions. Such explanation is critical to understanding how organisms respond to environmental change. At the same time, natural selection represents feedback from ecosystem conditions as these are altered by the activities of co-evolving organisms. The evolutionary and ecosystem perspectives are most complementary at the community level, where species diversity emphasized by the evolutionary approach is the basis for functional organization emphasized by the ecosystem approach.
Although the evolutionary approach has provided valuable explanations for how complex interactions have arisen, current environmental issues require an understanding of how insect functional roles affect ecosystem, landscape, and global processes. Insect ecologists have recognized insects as important components of ecosystems but have only begun to explore the key roles insects play as integral components of ecosystems. Insects affect primary productivity and organic matter turnover in ways that greatly alter, and potentially regulate, ecological succession, biogeochemical cycling, carbon and energy flux, albedo, and hydrology, perhaps affecting regional and global climate as well. These roles may complement or exacerbate changes associated with human activities. Therefore, the purpose of this book is to address the fundamental issues of insect ecology as they relate to ecosystem, landscape, and global processes.
Was this article helpful?