IV. Ecology • Definitions • Symbiotic Relationships • Biogeochemical Cycling • Ecological Succession • 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
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
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