The genetic basis of community organization and its implications for management solutions to global change
Foundation species structure a community by creating locally stable conditions for other species. When foundation species exert their effects, selection occurs within a community context, causing distinct communities to become associated with particular foundation species genotypes. This process illustrates the genetic basis of community organization, wherein the rate of change in relative fitness among dependent species is proportional to the genetic variance underlying foundation species traits. The evolutionary changes caused by such selection are responsible for the observed phenotypic covariance of communities on related host plants (e.g., in estimates of broad and narrow-sense community heritability). These changes yield predictable patterns in community organization over a wide range of spatial and environmental scales (e.g., in genetic scaling models and the “genetic similarity” rule). They are also readily reproduced in simulations in which the genotypes of host plants and the fitness consequences they have on community members are explicitly known.
Theoretical work shows that selection within a community context is measurable and reveals the existence, the intensity and the possible evolutionary outcomes of interactions among foundation and non-foundation species. Simulation results suggest that interactions involving two foundation species, e.g., cottonwood trees and beavers, may have synergistic as well as antagonistic effects on biodiversity. These results have considerable implications for management solutions to global change because foundation species genotypes, and their associated species, are likely to respond differentially to environmental change, possibly complicating restoration efforts that do not incorporate this information. To illustrate how these relationships may be explored and put to practical use, I describe theoretical and empirical projects that examine the effects of foundation species on each other and on their dependent species, within common gardens, and with the collaboration of resource managers. Such interdisciplinary networks will inform efforts to understand the effects of within- and among-species interactions on community organization, they will help anticipate ecological responses to new environments, and they will guide resource management solutions to global change.