Unit 8 Notes: Populations

(1) Population Characteristics Geographic Distribution: The area/s inhabited by the population. Density: Number of organisms per unit area within the population’s habitat. Growth Rate: How fast the population increases or decreases in size over time.

(2) Population Growth 3 Factors Affect Growth: Number of births Number of deaths Number of organisms entering/leaving

(3) Immigration vs Emigration *This is like when we discussed genetic migration in evolution. Immigration = Movement of organisms into the population (causes growth). Emigration = Movement of organisms out of the population (causes decline).

(4) Exponential vs Logistic Growth Exponential  When the individuals in a population reproduce at a constant rate. Logistic  When the growth slows or stops after a period of exponential growth. Under ideal conditions with unlimited resources, all populations will grow exponentially. However challenges like finding a mate, available resources and disease normally prevent this.

(5) Carrying Capacity The largest number of individuals that a given environment can support. Factors that Determine the Capacity: Available resources Disease Predation & Food Competition Climate Human Activity