Compromise Compromises often occur when members of a system compete with each other. It is one of the most widespread recognitions of coexistence in communities. The "Darwinian demon" theory stated that "tradeoffs between survival and reproduction, however, prevent any organism from realistically resembling this creature." Similarly, the "Hutchinson demon" theory also highlighted that "one species in a community dominates because it is best placed to colonize new patches, using all resources, avoiding predators and resistant to stress. Trade-offs in a community can be controlled by several limiting factors, such as resource scarcity, abiotic factors like pH, salinity, the presence of sunlight, and the presence of competitors. Interspecific trade-offs are generally considered a necessary condition for the coexistence of species within communities at small spatial scales. In the context of metacommunities, trade-offs are still often seen as imperative for coexistence on a regional rather than a local scale. There are three elements of trade-offs between competing species within a trophic level, such as the interplay between local and regional trade-offs, coexistence and trade-offs at regional scales, and species diversity at multiple spatial scales (alpha , beta, gamma). Because environments are diverse and patchy, species may exhibit trade-offs in their ability to use local habitats and exploit patches regionally. When dispersal rates are low, each species persists only in the type of habitat in which it is favored; local diversity is low. In contrast, at the highest dispersal rates, species that are better at colonizing empty patches can dominate and drive other species to extinction, even if those species...... middle of paper...... species and different species are favored in different environments. As dimensionality increases, control of community dynamics should shift from local to regional processes. Species can coexist on a local and regional scale by specializing on a specific habitat. Specialists, by definition, have the highest fitness in a particular habitat and the trade-off then manifests between habitat types, whereas generalists do not exhibit trade-offs between habitat types. Coexistence on a local scale will occur between habitat generalists and specialists, while coexistence on a regional scale will occur between specialists and generalists of different habitats. Increasing connectivity between patches can decrease beta diversity and increase alpha diversity in some situations; dispersal rates essentially change the relative importance of trade-offs at local and regional scales.