POPULATIONS

POPULATIONS

DEFINITION: GROUP OF ORGANISMS OF THE SAME SPECIES LIVING IN A GIVEN GEOGRAPHIC AREAEXAMPLES: BEE HIVE, ANT HILL, FLOCK OF GEESE, DANDILIONS IN A LAWN, POD OF WHALES, PEOPLE!

BIOTIC LIMITING FACTORSBENEFICIAL• EASE OF

REPRODUCTION• FIND FOOD

• PROTECTION

HARMFUL• DISEASES SPREAD

EASIER AND FASTER

• COMPETITION AND CONSUMPTION OF RESOURSES

• HUMAN INFLUENCES

POPULATIONS GROW EXPONENTIALLYIF LIMITING FACTORS ARE RESTRICTED

WHAT DO YOU NOTICE ABOUT THESE TWO GRAPHS?

THIS GRAPH ILLUSTRATES A POPULATION WHRE THERE ARE FEW LIMITING FACTORS

CONTROLLING GROWTH

THIS GRAPH ILLUSTRATES A POPULATIONWHRE LIMITING FACTORS ARE CONTROLLING

GROWTH

‘J’ CURVE‘S’ CURVE

CARRYING CAPACITYThe maximum population of a given species that can survive indefinitely in a given environment.

WHAT IS THE APPROXIMATE POPULATION SIZE OF HARES THAT THIS ENVIRONMENT CAN CARRY? LYNX?

GLASS SLIPPER

How would you count members of the following populations?

• Large mouth bass in Lake Lanier• Bacteria E. coli growing on a petri dish• Blue jays in Smokey Mtn National Park• Periwinkle snails on marsh grass• Live oak trees in South GeorgiaWhich were easiest? More difficult? What influenced your method of counting the most?

TREES, SNAILS

BASS, JAYS, BACTERIA

MOVING? VISIBLE? NEED INSTRUMENTS?

HOW ARE POPULATIONS COUNTED?METHODS DEPEND UPON WHETHER OR NOT THE POPULATIONS ARE MOBILE OR STATIONARY; EASY TO SEE OR DIFFICULT TO ACCESS.RANDOM SAMPLING: METHOD USED FOR POPULATIONS THAT DO NOT MOVE. AN AVERAGE OF THE POPULATION SIZE IS MADE USING A GRID AND SELECTION OF SECTIONS AT RANDOM.

MARK AND RECAPTUREMETHOD USED FOR POPULATIONS THAT MOVE, OR ARE HIDDEN FROM VIEW. SAMPLE OF THE POPULATION IS CAPTURED, MARKED AND RETURNED. THEN THOSE RECAPTURED WITH MARK ARE COUNTED THOSE THAT AREN’T ARE MARKED.