ecology and biosphere. * study of the interactions of organisms with each other and their...
TRANSCRIPT
*Levels of Organization
*Population-group of organisms of same species in a specific area
*Community- all the populations in an area
*Ecosystem- community + abiotic factors
*Biome- Major ecosystem that occupies a broad geographic region influenced by climate and characterized by dominant vegetation
*Biosphere- all portions of Earth inhabited by life / all of Earth’s ecosystems
*Communities
A. Interactions1. Competition—usually for resources
* Niche—organism’s role in its environment~Can’t have 2 species with the same niche in the same area because of the Competitive Exclusion Principle—2 extremely similar species cannot co-exist in the same place because one will be slightly better at getting the resources and reproduce more.
* Resource Partitioning—resources are divided so that species can co-exist and each have it’s own niche
*Communities
2. Predation
* Animalanimal = predator / prey
* Animalplant = herbivory
3. Symbiosis
* Mutualism (+,+)
* Parasitism (+,-)
* Commensalism (+, 0)
*Communities
2. Length of Food Chain in Food Web
* Energetic Hypothesis—food chain can’t be long because there is an insufficient transfer of energy (10% Rule)
* Dynamic Stability—shorter chains are more stable because disruptions are magnified as you go up (the lower you wipe something out, the more effect it has)
*Communities
C. Community Stability1. Dominant Species—highest in terms of
biomass (usually a plant)
2. Keystone Species—not most abundant but most important due to ecological role. If it’s removed from ecosystem there’s a major effect
3. Succession—Predictable sequence of communities that follow each other after a disturbance
*Communities
*Succession Terms
*Disturbance—what originally “damages” ecosystem
*Primary Succession—start with a virtually lifeless area
*Secondary Succession—start with some biomass left
*Pioneer Species—first species to come into an area
*Climax Community—end stage / stable / due to climate
*Populations
A. Density: # of organisms/area* Quantitative
* 2 lions per mile2
* Qualitative
* The density of lions in my backyard is sparse.
B. Distribution: How organisms are arranged/placed* Determined by resources and social behavior
*Populations
D. Population Growth
*Variables:
dY = amount of change N = population size
dt = change in time K = carrying capacity
B = number of births rmax = maximum per D = number of deaths capita growth rate of population
b = per capita birth rate
m = per capita death rate
Population Growth:
dN = B – D OR dN = bN - mNdt dt
*Populations
Density Dependent Factors:
Population limiting factors whose effect depends on population density
Density Independent Factors:
Population limiting factors that are not dependent on population density
*Energy
A. Productivity—turning light into sugars
1. Gross Primary Productivity (GPP)—amount of light energy converted to chemical energy in photosynthesis over time
2. Net Primary Productivity—(amount of GPP) – (energy used by plant in cellular respiration [R])
NPP = GPP – R
3. Limits on Production—sun (intensity, depth, penetration); limits on photosynthesis (water); limiting nutrients (N & P)
*Energy
B. Ecological Pyramids (See Pictures)
1. Production / Energy—amount of energy stored at each level
2. Biomass—amount of biological mass at each level
3. Numbers—number of organisms at each level
*Matter
Biomagnification—retained substances become more concentrated as you go up the trophic levels