Ecological Niches of Sympatric Phytoplankton Species

Starting with Hutchinson's definition, a way of defining an organism's niche is described in which the defining qualities are not the Hutchinsonian abiotic and biotic variables themselves but rather various aspects of such variables based on the ways in which they influence the organism. Five aspects of an environmental variable are distinguished and defined. These are the linking, separating, rarifying, reinforcing, and variational. The last of these pertains to a higher level of discourse, being a description of the pattern of deployment of the other aspects. Adaptations to the variational aspect, being strategies for the deployment of the other adaptations, are termed meta-adaptations. The relevance of this scheme in describing niches of highly diverse phytoplankton populations, on the one hand, and pauci-specific blooms or laboratory cultures, on the other, is explored. Various kinds of solutions to the "paradox of the plankton" are discussed from this point of view. Throughout, examples and discussions of these ideas are largely restricted to the case of phytoplankton populations, but it is hoped that they may have more general applications.