Week7 Draft 3

The definition of competitve species is a species whos phenotypes causes a fitness decrease in a competitor species. In bacteria, this is observed in phenotypes such as secretion of digestive enymes and production of antibiotics as a result of biotic competition with other bacteria, as opposed to environmental pressures. Competitor species must also overlap a single resrouce. When this occurs, there are two types of competition, passive and active. In passive competition, one organism outcompetes the other by using the same resource more efficiently. In active competition, the organism may directly harm the other. In the case of bacteria, this may be done by producing chemicals that harm other bacteria of the same niche. Thee possible results of such competition include having one species dominating the other, coexistence over time due to divergence of resource use, or territorial niches are developed. The later is observed in microbial colonies that when initially mixed, separate into patches on the surface of agar. The result of competition is typically a decrease in diversity but increase in ecological stability. The long-term effect depends on selection pressures of the environment.