Community Ecology Ch. 20

(20-1) Species Interactions 5 major types –Predation –Competition –Parasitism –Mutualism –Commensalism

Predation 1 species benefits (predator) while the other species gets eaten (prey) Adaptations: –Mimicry –Secondary compounds –Physical abilities

Predation (cont.) Mimicry: harmless species resembles a poisonous or distasteful species –Ex: king snake mimics poisonous coral snake Secondary Chemicals: poisonous or bad-tasting chemicals made from metabolism –Ex: poison ivy/oak

Competition Caused by niche overlap of 2 or more species Can lead to: –Competitive exclusion –Character displacement –Resource partitioning

Competitive Exclusion 1 species is eliminated due to competition for same limited resource –2 barnacle species

Character Displacement Evolution of anatomical differences that reduce competition –Darwin’s finches

Resource Partitioning Species reduce their use of shared resource thus decrease competition –Warbler feeding

Symbiosis Relationship b/w different species living in close contact w/ each other 3 types: 1. Parasitism 2. Mutualism 3. Commensalism

Parasitism 1 species benefits (parasite) while the other species is harmed (host) 2 types: –Ectoparasite: external Ticks, fleas, leeches –Endoparasite: internal Tapeworms

Mutualism Both species benefit from one another –Pollinators & plants

Commensalism 1 species benefits while other is not affected –Cattle egrets & Cape buffalo

(20-2) Properties of Communities 3 community characteristics: –Richness: # of species it contains –Diversity: how common a species is –Stability: resistance to change Richness improves stability

Species Richness Patterns Communities closer to the equator have more species Species-area effect: larger areas usually contain more species than smaller areas

Succession Gradual, sequential re-growth of species in an area

2 Types of Succession Primary: development of a community in an area that never had life before –Bare rock, sand dune –Extremely slow process Secondary: change of community makeup after a disturbance –Farming, flood, fire –~100 yrs to return

Key Terms Pioneer species: predominate in early succession –Small, fast-growing, & fast- reproducing –Ex: weeds, crabgrass Climax community: community make-up that will last for a long time –Stable end result of succession