Chapter 37.1 – 37.6 COMMUNITY ECOLOGY

What you need to know! The community level of organization The role of competitive exclusion in interspecific competition The impact of keystone species on community structure. The symbiotic relationships of parasitism, mutualism, and commensalism

Community All the organisms of various species that live close enough to interact 4 characteristics: 1.Species diversity: variety of species a)Species richness = total number of species b)Species abundance = the amount of each species i.e.Community 1: 25 A25 B25 C25 D Community 2: 97 A1 B1 C1 D 2.Dominant Species: typically most abundant species 3.Response to disturbance: ecological succession 4.Trophic structure: energy, feeding relationships, nutrient cycles

Interspecific Competition Competition between species for resources that share the same habitat Predators competing for prey Plants competing for soil Habitat: where the organism lives Niche: what the organism does in its habitat Competitive exclusion principle: no two species can occupy the same niche in the same habitat at the same time Resource partitioning is when organisms live in different regions of the same habitat so they cancoexist (realized niche)

Keystone species exert strong control of an ecosystem Keystone predators tend to reduce the population of the strongest prey species This provides an opportunity for lesser species to find niches within the habitat Unique adaptation: Camouflage developed as a result of predation Chemical defenses are common among dangerous prey Batesian mimicry is when something harmless looks like something harmful Müllerian mimicry is when two harmful species look similar Predator and Prey

Symbiosis Close relationships that develop through coevolution (evolving together) 3 types 1.Mutualism: both species benefit 2.Commensalism: one species benefits 3.Parasitism: one species benefits the other is harmed

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