Community (ecology)


Community ecology or synecology is the study of the interactions between species in communities on many spatial and temporal scales, including the distribution, structure, abundance, demography, and interactions between coexisting populations. The primary focus of community ecology is on the interactions between populations as determined by specific genotypic and phenotypic characteristics. Community ecology has its origin in European plant sociology. Modern community ecology examines patterns such as variation in species richness, equitability, productivity and food web structure (see community structure); it also examines processes such as predator-prey population dynamics, succession, and community assembly.
In the neutral theory view of the community (or metacommunity), popularized by Hubbell, species are functionally equivalent, and the abundance of a population of a species changes by stochastic demographic processes (i.e., random births and deaths). Each population would have the same adaptive value (competitive and dispersal abilities), and local and regional composition would represent a balance between speciation or dispersal (which increase diversity), and random extinctions (which decrease diversity).
Predation is hunting another species for food. This is a positiveľnegative (+ ?) interaction in that the predator species benefits while the prey species is harmed. Some predators kill their prey before eating them (e.g., a hawk killing a mouse). Other predators are parasites that feed on prey while alive (e.g., a vampire bat feeding on a cow). Another example is the feeding on plants of herbivores (e.g., a cow grazing). Predation may affect the population size of predators and prey and the number of species coexisting in a community.
Commensalism is a type of relationship among organisms in which one organism benefits while the other organism is neither benefited nor harmed. The organism that benefited is called the commensal while the other organism that is neither benefited nor harmed is called the host. For example, an epiphytic orchid attached to the tree for support benefits the orchid but neither harms nor benefits the tree. The opposite of commensalism is amensalism, an interspecific relationship in which a product of one organism has a negative effect on another organism but the original organism is unaffected.