Monday 10.5.15
Review
• Ecology examines the relationships within and
between the levels of organization
• Organism level  how an individual relates to
its environment and maximize its survival
– Habitat
• The living and non-living elements. Where an organism
lives
– Niche
• The role (job) of the organism
Species Interactions
• Organisms interact on many levels
– Can be
• Intraspecific interaction between members of the
same species
– Examples: competition for resources
cooperation to get a resource
• Interspecific  the interaction between two different
species
– Examples: competition for resources
one eats another
division of tasks
Competitive Interactions
• Competition occurs when organisms seek a
common resource
– Subtle competition
• The better forager finds more food
• The male with the best territory gets the ladies
• Individuals with fewer visible parasites get more mates
• Competitive exclusion
– If one competitor has a
significant enough
advantage, it can exclude
the other from the area
– This is rare  usually the
competitors will divide up
the resources
• Competition is not good for either party
– Neither competitor reaches full use of the
resource unless competitive exclusion occurs
Exploitation Interaction
• Happens when one species benefits to the
detriment of another
• Three types:
1. Predations – one animal eating another
2. Parasitism – an individual exploits a host without
killing it
3. Herbivory – an animal eating a plant
Predation
• Predators help regulate prey populations
– Predator and prey populations tend to follow each
other
– When prey are plentiful, predators have more
surviving offspring
– When prey are scarce, predators have fewer
surviving offpspring
• There are many levels of predators
– The predator of one species may be prey to another
• Example – snake preys on mice, but is eaten by hawk
Parasitism
• When one organism is exploiting another
– Not all species that exploit others actually kill their
prey
– Can be internal or external
• Internal – bacteria, worms, protists
• External – fleas, ticks, leeches
Herbivory
• An animal eating a plant
• Plants often survive
• Most herbivores are insects
Mutualistic Interactions
• Happens when both parties benefit from the
interactions
• Typically each organism provides a resource
that the other can’t get or produce
• Occurs between species that are in close
contact
– Coral – coral and algae
– Coral provides protection and nutrients
– Algae provides energy
• Some cases of mutualism occur when the
species are not always in close proximity
– Example – pollinators and pollen from flower
Commensalism Interaction
• One species benefits from another which is
unaffected
– Example – algae on turtle shell
What type of interaction(s) have a
+/- relationship?
Communities
Food Web
Biomes
Bell Ringer
Notes
Project
Introduction
Communities
• Communities consist of all species living in a
given area at that time
• Community ecology
– How to species coexist?
– What interactions occur?
– How do communities change over time?
• Species within communities are generally
classified by which tropic level they fall into
• Tropic level – where in the food chain an
organism resides
• Biomass – amount of organic material
• Producers
– Organisms that harvest energy usually from the
sun
– Called autotrophs – ‘self feeder’ because of ability
to harvest energy to create food
– Typically plants, bacteria, and some protists
– Most energy stored in these levels… why?
– What is the original source
• Consumers
– Eat producers, consumers, and decomposers
– Called heterotrophs – ‘other feeders’ because they must
eat other living things to survive
• Classified by how many trophic levels are below it
– Primary consumer – herbivores – eat plants
» Deer, grasshoppers, rabbits, blue wale
– Secondary consumer – eats primary consumer and possibly producers
» Wolves eat deer
– Tertiary consumers – eats primary and secondary consumers
» Hawks eat snakes
• Decomposers
– Eat non-living materials
Transfer from one level to another is
not 100%
1. not all energy the energy at one level is
transferred to the next trophic level (some
organisms are not eaten)
2. some energy is used by the organisms at each
trophic level to maintain life
3. 3. chemical reactions at each trophic level are
not 100% efficient
Food Web