IV. Ecology

A. Definitions

B. Symbiotic Relationships

C. Biogeochemical Cycling

D. Ecological Succession

E. Georgia’s barrier islands: An example of ecosystem dynamics

A. Definitions Ecology

– The study of the interaction of populations of living organisms with other populations and with the environment

– Population A group of individuals, all of the same species

– Community A group of different populations

– Physical factors in the environment Oxygen concentration, salinity, temperature, rainfall,

etc.

B. Symbiotic relationships Symbiosis

– A relationship between two species– Usually involves close physical contact– The major types are mutualism,

commensalism, parasitism, and predator-prey relationships

B. Symbiotic Relationships

Mutualism– A symbiotic relationship between two species– In which both species benefit– Example:

Microbes in the stomach of cattle are responsible for the digestion of cellulose (fiber in grass & hay)

The cattle benefit because they use the glucose from the cellulose digestion

The microbes benefit because they get a warm, moist, protected place to live

B. Symbiotic Relationships

Commensalism– A symbiotic relationship between two species– In which one species benefits, and the other

species is neither helped nor harmed– Example:

Small worms living attached to the shells of loggerhead sea turtles

The worms benefit because they get to travel through nutrient-rich waters as the sea turtle swims around (worms attached to the docks are stuck there)

There is no direct benefit to the turtle having worms stuck on its back, nor does there seem to be any harm done

B. Symbiotic Relationships

Parasitism– A symbiotic relationship between two species– In which one species benefits, and the other

species is harmed– The species that benefits is called a parasite,

and is typically much smaller than the other species (the host)

– Example: Pathogenic microorganisms that cause disease in

humans, animals, and plants

B. Symbiotic Relationships

Predator-prey relationship– A symbiotic relationship between two species– In which one species captures & kills the other

species for food– The species are generally about equal in size– The term is usually applied to animal species (or

certain types of protozoan species)– Example:

Lions and wildebeests, cougars and rabbits, etc.

C. Biogeochemical cycling

Definition The carbon cycle The nitrogen cycle

Carbon Cycle

Nitrogen Cycle

D. Ecological Succession Definition

– A series of changes in the ecological community that inhabits an area or region

– Occurs because the activities of living organisms (and nonbiological physical factors) change the conditions of a region (for example, soil chemistry) so that the region becomes more conducive to a different group of organisms

Bare Rock Succession– An example of primary succession:

Succession beginning in an area or surface on which there has never been life before

Old Field Succession An example of secondary succession:

Succession that occurs in a region in which life has existed before, but in which the previous community structure has been disrupted

Frequently seen in North Georgia where cultivated fields (e.g. old cotton or soybean fields) are abandoned and no longer cultivated

Old Field Succession

D. Ecological Succession Beach succession: Another example

of secondary succession The normal flora of humans: A medical

example

E. Georgia’s Barrier Islands

Formation of the barrier islands Beach building and erosion processes Beach dune shrub zone

maritime forest succession Salt marsh / estuarine ecosystems Web sites:

http://www.sherpaguides.com/georgia/barrier_islands/index.htmlhttp://www.sherpaguides.com/georgia/coast/northern_coast/ossabaw_island.htmlhttp://web.utk.edu/~ctmelear/ossabaw/movies/ossabawscenery.html