Community ecology AP Biology Chapter 53

Community An assemblage of populations of various species living close enough for potential interactions

Species Diversity Species richness: Relative abundance: Total amount of species in a community Relative abundance: Total amount of one species in a community

Competitive Exclusion Principle Direct interspecific competition will always lead to the extinction of one species One species will have a slight competitive edge in surviving and reproducing

Ecological Niche Every species survives and reproduces utilizing a range of chemical and biological conditions

Species Interactions

Types of Interactions Interspecific Interactions Interactions with other species Intraspecific Interactions Interactions within one species

Predation (+/-)

Evolution of Coloration Cryptic: animal blends in to surroundings Aposematic: animal is brightly colored (warning)

Evolution of Coloration Batesian mimicry: smaller species is harmless Mullerian mimicry: both species are harmful

Herbivory (+/-)

Parasitism (+/-)

Mutualism (+/+)

Commensalism (+/0)

Food Chain A linear relationship that illustrates how energy flows in an ecosystem.

Food Web A collection of interconnecting food chains

Keystone Species Organism with a pivotal role in an ecosystem The removal of a keystone species results in the collapse of the ecosystem Ex: sea otter (Enhydra lutris)

Disturbance An event that changes a the dynamics of a community

Primary Succession Formation of a community in a place without soil Volcanoes Landslides Flooding

Primary Succession Pioneer species arrive that do not need soil Ex: photosynthetic prokaryotes & windblown spores

Primary Succession Pioneer species decompose into organic matter Rocks erode into minerals forming soil

Primary Succession Simple plants like mosses and ferns grow in soil

Primary Succession Grasses and wildflowers replace seedless plants

Primary Succession Over time, forests replace prairies

Primary Succession Animals have a substantial habitat

Secondary Succession Soil already present Faster than 1º succession Different pioneer species Ex: fires

Climax Community A stable group of plants and animals that is the end result of the succession process Does not always mean forest Grasses in prairies Cacti in deserts