Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Ecology: The study of how organisms interact with each other and the environment.

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Ecology Definitions: Habitat: The space or environment when an organism lives Niche: role of an organism in a community Biotic Factors: All the living things within an environment Abiotic Factors: All the physical (non-living) things in an environment

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Connections to the size of the acorn crop

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Limiting Resources Environmental factors that restrict the growth of populations.

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Effect of competition on an organism’s realized niche

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Competition Two or more individuals attempting to use the same resource Intraspecific competition –Among individuals within a population Interspecific competition –Between different species

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Interspecific competition

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Competitive exclusion principle Two species cannot occupy the same niche in the same community for an indefinite period One species is excluded by another as a result of competition

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Some species reduce competition by resource partitioning Competition among species is reduced by character displacement Structural ecological and behavioral characteristics diverge where ranges overlap

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Resource partitioning

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Predation Consumption of one species (the prey) by another (the predator) Co-evolution Predator and prey both evolve more efficient ways to interact

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Ecological interactions among species

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Defenses Mechanical defenses Associating in groups Cryptic coloration Warning coloration Müllerian mimicry

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Cryptic coloration

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Symbiosis Mutualism –Both partners benefit Commensalism –One partner benefits and the other is unaffected Parasitism –One partner benefits while the other is harmed

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Mutualism between flowering plants & pollinators

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Mutualism between clown fish & sea anemone Mutualism between clown fish & sea anemone

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Commensalism: Spanish moss & trees

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Parasitism: Ticks and Mammals

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Parasitism

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Keynote species Present in small numbers but are crucial in determining the species composition and ecosystem functioning Dominant species Affect the community because they are so common

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Species richness Number of species within a community Species diversity Relative importance of each species within a community

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Effect of community complexity on species richness

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Ecological Succession Primary succession –Occurs in an area not previously inhabited Secondary succession –Occurs where there is a pre-existing community and well-formed soil

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Ecological Succession Pioneer Species= annual plants/grasses Secondary Species= shrubs Climax Species= trees Ecological Succession Pioneer Species= annual plants/grasses Secondary Species= shrubs Climax Species= trees

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Intermediate disturbance hypothesis Disturbance affects succession and species richness Species richness is greatest at moderate levels of disturbance

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology Intermediate disturbance hypothesis

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 52 Community Ecology The nature of communities Organismic model –Views a community as a superorganism that goes through stages of development (succession) Individualistic model –Abiotic environmental factors are primary determinants of species composition –Organisms are independent