Population = A group of organisms of the same species living in the same place

Population Growth Exponential Logistic Population grows without limit Carrying Capacity: the theoretical maximum population that a given environment could support Exponential Population grows without limit Ex. Human population Logistic -Population grows quickly at first and then levels off -Ex. most natural populations (fish, rabbits, trees, etc.)

Then density dependent/independent factors take effect Population density measures the number of individual organisms living in a defined space. Pop. Density = # of organisms/space Determined by limiting factors such as… BIRTH IMMIGRATION DEATH EMIGRATION Then density dependent/independent factors take effect

Limiting Factors Limiting factors = Aspects of the environment that limit the size a population can reach. Limiting factors can be biotic (living) or abiotic (nonliving) Examples? Limiting factors can also be classified as density-dependent or density-independent. Try to get students to think of their own examples. Here are a few: Biotic: Competition, predation, disease (usually) Abiotic: Climate, natural disasters

Density-Dependent Limiting Factors Density-dependent limiting factors operate more strongly on large, dense populations than on smaller ones. These are factors that can be triggered by an increase in population size, and thus crowding. Ex. Competition, Predation, Parasitism, Disease

Density-Independent Limiting Factors Density-independent limiting factors regulate population growth regardless of its size or density. Nearly all species in an ecosystem are affected equally by density-independent limiting factors. Ex. Weather changes, pollution, natural disasters

A Stable Ecosystem is one that remains relatively constant, with predictable changes in population growth.

Survivorship Type I: Late loss; heavy parental care Ex. Humans Type II: Constant loss; mortality unaffected by age Ex. Some birds, rodents Type III: Early loss; produce lots of offspring at once and many die right away Ex. fish, mosquitoes