Transcript rocks, man-made items, rain, sunlight

Communities and Ecosystems
Chapter 37
I. Principles of Ecology
A. Beginnings of Ecology
1. This science rose from natural history
2. Ecology is the study of interactions between organisms
and their environment
3. Information is gathered through a lot of observational
studies within the environment (not so much in the lab)
B. Biosphere: portion of the earth that supports life
1. Biotic Factors – living things in the environment
a. examples: plants, humans, bacteria, animals, fungus
2. Abiotic Factors – nonliving things in the environment
a. examples: rocks, man-made items, rain, sunlight, temperature, soil, slope of land
b. these factors interact with each other
c. these factors affect the biotic factors
C. Hierarchy of life
1. Organism – a single individual of a species
2. Population – a group of organisms that live in the same
place at the same time that interbreed.
3. Community – a collection of interacting populations
4. Ecosystem – community + abiotic factors
5. Biosphere – living world + nonliving (bottom of the ocean
through the atmosphere)
D. Niche – the role a species plays in its community
1. would include what food it eats, how much space it
needs, how it finds food, when it is active, reproduction
habits etc.
2. The more similar two niches are, the more likely species
will compete for at least one resource. There is a limit to
how much niches can overlap. Result:
a. one species may go extinct
b. one species moves to another area, both survive
c. one species may adapt to a new niche
3. Competitive Exclusion Principle or Niche Rule – no two
species occupying the same niche can exist for long.
E. Habitat – where an organism lives
F. Interspecific interactions:
1. Symbiosis – “living together”, close and permanent association
between organisms of different species
a. Commensalism – one species benefits, the other is neither
harmed nor benefited from the relationship
Examples:
b. Mutualism – both species benefit
Examples:
Facultative mutualism– they can live without each other
Obligatory mutualism– they cannot live without each other
c. Parasitism – one species benefits, the other is harmed
“Host” – the species being harmed
Examples:
Tissue Parasitism – one species eating the tissue of another
Social Parasitism – one species exploits the labors of another
2. Interspecific competition – competing for same limited resource
Examples:
3. Herbivory – consumption of plant parts or algae by an animal
4. Predation – leads to diverse adaptations in prey species
Examples:
G. Trophic structure
a. Producer – “autotroph”– organism that makes its own food
b. Consumer – “heterotroph” – get energy from the producer directly or
indirectly
Primary consumer – herbivore (eats producers)
Secondary consumer – eats herbivores
Tertiary consumer – eats secondary consumers
Quaternary consumer – eats tertiary consumers
c. Carnivore – eats other heterotrophs
d. Scavenger – eats dead animals
e. Omnivore – eats both heterotrophs and autotrophs
f. Herbivore – eats plants (primary consumer)
g. Insectivore – eats insects
h. Decompose aka “detritivores” – breaks down dead matter into simple
compounds to be reabsorbed.
H. Energy flow through an environment
1. Energy originates with the sun
2. Food Chain – simplest feeding relationship
a. 4-5 levels maximum (why not 20?)
as energy flows through a food chain, it is lost
(popcorn demo outside)
b. more energy is available at the lower end of the chain
3. Food Web – food chains interlinked and overlapped
within a single ecosystem
H. Nutrient Cycles – food chains and food webs show energy
being moved in one direction. Energy is lost while nutrients
are recycled.
1. Water Cycle: 3 processes
involved
a. evaporation – liquid to gas
(heat)
b. condensation – gas to liquid
(cool)
c. precipitation – falling water
2. Carbon/Oxygen cycle
a. sources of carbon – animals exhaling, fire, burning fossil fuels, decomposition
b. sources of Oxygen – plants give off
c. Carbon leaves environment – plants take in
d. Oxygen leaves environment – inhale of animals, fire
3. Nitrogen cycle
a. 78% of the air is Nitrogen (in a form plants and animals
cannot use) Why do we need nitrogen? Proteins, DNA
b. Nitrogen Fixation – process where bacteria in the soil
convert atmospheric nitrogen to a usable form called
“nitrate”
c. Plants absorb nitrates and use them to make protein and
DNA
d. Nitrogen then goes through the food web as proteins
e. Denitrification – process where bacteria in the soil
convert proteins (from dead plants and animals) to
atmospheric Nitrogen
4. Phosphorus cycle
a. why do organisms need phosphorus?
b. rocks are the source of phosphorus for terrestrial
ecosystems
c. weathering rock adds PO43d. plants absorb and use them to make organic
compounds
e. food chain
f. decomposers break down animal waste or dead
organisms
g. phosphorous drains into sea where it may settle and
become a part of new rocks
h. geologic processes uplift the rocks to expose them to
weathering.