Tradeoffs Tradeoffs often occur when members of a system compete with each other. It is one of the most widespread recognitions for coexistence in communities. The “Darwinian demon” theory indicated that “trade-offs between survival and reproduction, however, prevent any organism from realistically resembling that creature.” Similarly, “Hutchinson's demon” theory also emphasized that “one species in a community dominates because it is better at colonizing new areas, using all resources, avoiding predators and resisting stresses.” Trade-offs in a community can be controlled by several limiting factors, such as resource scarcity, abiotic factors such as pH, salinity, the presence of sunlight, and the presence of competitors. Interspecific trade-offs are generally believed to be a requirement for the coexistence of species in communities at small spatial scales. Within the meta-community context, trade-offs are still often considered imperative for coexistence at regional rather than local scales. There are three elements of trade-offs between competing species at the trophic level such as the interaction between local and regional trade-offs, coexistence and trade-offs at the regional scale, and species diversity at multiple spatial scales (alpha, beta, gamma). When environments are diverse and patchy, species may exhibit compromises in their ability to use local habitats and exploit regional areas. When dispersal rates are low, each species persists only in the habitat type in which it is favored; local diversity is low. Conversely, at higher dispersal rates, species that are better at colonizing empty patches may dominate and drive other species to extinction, even if those species… favored in different environments. As dimensionality increased control of community dynamics, a shift from local to regional processes was expected. Species can coexist on a local and regional scale by specializing on a specific habitat. Specialists, by definition, have the greatest fitness in a particular habitat and trade-off is therefore shown between habitat types, while generalists show no trade-off between habitat types. Local-scale coexistence will occur between generalists and habitat specialists, while regional-scale coexistence will occur between different habitat specialists and generalists. Increasing connectivity between patches can decrease beta diversity and increase alpha diversity in certain situations; dispersal rates essentially shift the relative importance of trade-offs at local and regional scales.