Community Interations Ecology Community Interations

Community Interactions An ecological community consists of all the interating populations within an ecosystem, in other words, community is the biotic component

Competition What are the effects of competition among species? Harmful ? Beneficial ?

Competition What is interspecific competition? Two or more species attempt to use the same limited resources, particularly food and/or space In interspecific competition, each species involved is harmed, because access to resources is reduced.

Competition The severity of the harm is determined by the level of overlap in ecological niches of the two competitors. An ecological niche encompasses all aspects of its way of life.

Competition Adaptations reduce the overlap of ecological niches among coexisting species Just as two objects can’t occupy the same space at the same time, two species can’t occupy the same ecological niche at the same time, competitive exclusion principle Put two species of the same niche in an ecosystem and one will die out

Competition This is true if the niches they occupy are static, but this is not true. In this situation resource partitioning may come into effect Each of the competing species reduces it’s niche in order to survive

Competition Because individuals of the same species generally occupy the same niche intraspecific competition is a major factor in controlling population size. A predator is anything that’s eats another organism, killing it in the process. (what might this include?)

Predation Due to thier natural relationship predators and prey exert coevolutionary forces on each other. One wants to hunt more efficiently The other wants to stay alive

Predation Examples of coevolution Camouflage Warning coloration (wasp) Mimicry (stick insect) Aggressive mimicry (predator) Startle coloration (false eyes) Chemical warfare

Symbiosis Symbiosis – which literally means “living together” is defined as a close interaction between organisms of different species for an extended time. We will discuss three types of symbiosis Commensualism Mutualism Parasitism

Symbiosis Commensualism – is a relationship in which one species benefits while the other is relatively unaffected Barnacles that attach themselves to the skin of a whale, for example, get a free ride through nutrient-rich waters without harming the whale

Symbiosis Parasitism – one organism benefits by feeding on another Things such as tapeworms, fleas and numerous disease-causing protozoa, bacteria, and viruses.

Symbiosis Mutualism – when two species interact in a way that benefits both. The clown fish takes shelter among the venomous tentacles of the anemone, which are harmless to it. The fish derives shelter and protection and , at least occasionally, it brings bits of food to its anemone