Community Ecology

• Community Ecology

  The study of pattern and processes involving at least two species at a particular location
• Community Ecology Focuses on

  interactions between species, how communities change (community dynamics) and effects of disturbances (how communities develop/recover
• types of species interactions

  Consumption, competition, mutalism and commensalism
• Consumption (+/-)

  One organism eats another, 3 types, predation, herbivory and parasitism
• Predation

  One organism (PREDATOR) kills and consumes most/all of the other organism (PREY)
• Herbivory

  plant eaters (HERBIVORES) eat PLANT tissue
• Parasitism

  A symbiotic interaction in which one species (parasite) feeds off the tissue/nutrients of another (host, but the parasite rarely kills the host
• Adaptions for feeding

  Predators/herbivores have many adaptations for feeding including location (sensory systems), capture/eating (special behaviors/mouthparts, anatomical structures) and food processing (specialized teeth/digestive systems
• Behavioral Prey Defenses

  hiding, running, changing appearance, making yourself look bigger, playing dead, flighting, flocking/schooling, spraying chemicals and acting aggressive
• Morphological Prey Defenses

  cryptic coloration (camouflage), mechanical defenses (spines, prickles, shells, thorns) warning coloration (common in organisms with chemical defenses), eye spots, startlement, and mimicry
• Chemical Prey Defenses

  stored in tissues, spraying, some can make chemicals themselves while others get them from their food
• Defenses mimicry

  one or more species closely resemble another, two types Mullerian and Batesian
• Mullerian Mimicry

  both species look alike but both are harmful
• Batesiam Mimicry

  A harmless species mimics a harmful one
• Mimicry Ring

  Large assemblages of species, both Mullerian and Batesian mimics exhibiting the same color patterns
• Intraspecific

  Between members of the same species
• Interspecific

  between members of differet species
• Symmetrical competition

  Both species have equal decreases in fitness
• Asymmetrical competition

  Reduction in fitness is more in one species than the other
• Competitive exclusion

  One species is eliminated from the area
• Competitive exclusion principle

  Populations of two or more species cannot coexist indefinitely if they rely on the same limiting resources and exploit them in the same way
• Niche compression

  when competition narrows down the resoucres used
• Fundemental niche

  niche in the absence of competition
• Realized niche


  niche used when competition occurs
• Resource partitioning

  use of resources in different ways or at different times
• Character displacement

  the phenomenon that species occurring separately are similar in appearance and resources use, but when they occur together they look different and use different resources
• Rewards of mutualism

  -transportation of gametes, -food, -housing, -medical help, -protection
• Plant-pollinator interaction

  Bee eats nectar, feed pollen to larvae, carry pollen from one plant to others
• Cleaner Shrimp

  Shrimp eat parasites off the fish (dinner/medical attention)
• Rancher ants and aphids

  ants protect aphids, aphids feed ants sugary secretions
• Symbiosis


  Close ecological relationship between species or individuals, species live in direct or inimate contact
• Types of symbiosis

  Mutualistic (ants and Acacia trees), Commensaltistic (Follicle mites and humans) and Parasitic (Tapeworm and host)
• Species Richness

  number of species in an area
• Evenness


  -the extent to which the species in a community are equally abundant, similar species abundance within the community = higher evenness
• Diversity

  Includes both richness AND evenness
• Species composition

  Identity of all the different organisms that make up a community
• Community dynamics

  changes through time, responds to living and non-living factors, disturbances
• Disturbance 


  events that removes individuals/biomass
• Succession

  Gradual change in a community's species composition
• Climax community

  a relatively stable, late successional stage