Habitat construction and functional feedbacks: How organisms modify their external conditions

An overview of organismic impacts on the environment

The effects of organisms on their environments are ubiquitous, both individually and collectively, in the short term and over eons of time. Every plant, animal, bacterium, yeast cell, or other organism takes in resources and expels waste products, occupies space, absorbs or radiates energy, and so on. Whether positive or negative with respect to the organism itself, these external impacts inevitably shape the conditions of subsequent function and evolution in that habitat. This chapter explores the nature and variety of habitat-constructing effects of organisms, identifies conceptual and management issues, and presents detailed case studies of animals, plants, and bacteria. Tracing these effects in diverse systems reveals and reiterates an essential feedback cycle from individual or- ganismic activities (which are themselves influenced by environmental conditions) to external environments, and back to the organisms. This perspective on familiar ecological scenarios focuses attention on the reciprocal influence of phenotypic expression on environmental conditions, opening new questions framed explicitly around these fine-scale physiological, behavioral, and developmental effects and providing insights to higher-level downstream consequences.

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