Populations

Essential Questions What factors influence changes in populations? How do species interact with one another?

Population All of the members of the same species living in the same area. Inbreeding Isolation

Population Density The number of individuals per area Usually per square mile Washington, CT – 96 people/sq. mi. Shelton, CT – 1,294 Manhatten – 71,201 people/sq. mi.

Population Dispersion How individuals are distributed within their range Even Clumped Random

Growth Rate Birth Rate – Death Rate What factors affect birth and death rates?

Reproductive Potential The maximum number of offspring that an individual can produce. Elephants: 19 mm offspring in 750 years Bacteria: 19 mm offspring within days

Reproductive Potential What factors affect reproductive potential? How early reproduction begins * most important factor How often can individual reproduce How many individuals can be produced

Reproductive Potential elephants: 1 offspring every two years sexual maturity 9-12 years house mouse: litters of 10 or more 10 times a year sexual maturity within 5 weeks

Generation Time The length of time required for an individual to reach sexual maturity shorter generation time = greater reproductive potential

Exponential Growth Rapid growth in which population increases by certain factors with each generation No limiting factors: food, space competition predators

Limits to population growth

Carrying Capacity The maximum population an ecosystem can support Carrying capacity hard to determine ecosystems change many factors average populations

Limits on Resources Carrying capacity reached when resources are used up at same rate as they are replaced.

Limiting Resource Resource that determines the carrying capacity of a species.

Competition Within species Territoriality social response to limit competition with other species invasive species

Density and Population Regulation

Density Dependant Degree of regulating effect depends on density. limiting factors, predation, and disease reproduction

Density Independent Degree of regulating effect not dependant on density natural disasters, weather, climate shift