Chapter 53:Community ecology

• interacting species, usually living within a defined area
• ex.2 species interacting

• 1.they affect thr distribution and abundance of the inetracting species
• 2.they are agents of natural selection

occurs when individuals use the same resoruces, resulting in lower fitness(-/-)

when two species interact in a way that confers fitness to both (+/+)

occurs when one species but the other species is unaffected (+/0)..The least studied

One organism eats another, increasing the predators fitness but decreases the prey(+/-)

animal eats plant. (+/-)

• competition that occurs between memebers of the same species
• -Occurs when the niches of two species overlap

• occurs when individuals from different species use the same limiting resources
• ex. the barnacles>>>>Chthamalus(high tidal area); Balanus(low tidal area); Balanus outcompetes Chthamalus from coming down

the range of resources that the species is abe to use or the range of conditions it can tolerate

Not possible for species with the same niche to coexist

one species suffers a much greater fitness decline than the other species does

each of the interacting species experiences a roughly equal decrease in fitness

• the combination of resources or areas used or conditions tolerated in the absence of predators
• -always larger larger than the realized

the portion of resoruces or areas used or conditions tolerated when competition occurs

• an evolutionary change in resource use, caused by competition.
• ex.if 2 species compete over a resource(middle part), then overtime they would grow apart so they would not be competing(no more middle part would remain in the ven diagram)

• the change that occurs in species traits, and that allows individuals to exploit different resources
• Ex. Galapagos Finches

when harmful species resemble each other

when non-harmful species resemble harmful species

defensive traits that are produced only in response to the presence of a predator

any event that removes biomass from a comunnity

when a disturbance removes the soil and its organism. Ex.Glaciers, floods, volcanic eruptions

• when a disturbance removes some or all organism but leaves the soil intact.
• ex.Fires

early successional communties are dominated by species that are short-lived and small in stature

Late successional communities are dominated by species that tend to be long-lived, large and good competitiors for light and nutrients

tend to have "weedy" life histories. adapted for growth in distrubed soils

early species makes condtions more favorable for the next species. Shade/nutrients

existing species do not affect how the new species establishes

one species inhibits the establishment of another

how many species are present in a given community

• incorporates the number of species in an area and also their relative abundance
• -(How common or how rare compared to other species) Eveness

1.larger islands2.nearshore islands

the region with a moderate type, frequency, and severity of disturbance should have high species richness and diversity

-the evolution of traits that reduce niche overlap and competiton

-they make efficient use of resources, because they are produced only when needed

• 1.latitude
• 2.productivity
• 3.island size

-the amount of energy that is stored in standing biomass per year

herbivore populations are kept at relatively low levels by predation and disease

plant matter is low in nitrogen or defended by chemicals that are toxic to herbivores