Populations

Population Density The number of individuals in a specific area. Population Density = number of individuals unit area Example: Supposed there are 30 turtles in a 15 square foot area. 30/15= 2 or 2 turtles per square feet

Determining Population Size Direct Observation Actually count all of the members of that population Indirect Observation Observe tracks or other signs of the organism Example : There are an average of 4 birds in a nest, there are 30 nest. 4*30= 120 birds in the area Sampling- Estimate the number of the population in a small area then multiple. Example: There are 3 turtles in 2 square feet. If the area is 50 square feet. 3*50= 150 turtles in the area.

Changes in Population Size Births and Deaths- population size when new members enter or when members leave. Birth rate-number of births in a certain amount of time Example- If 500 turtles are born in a populations in a year. The birth rate is 500 turtles per year Death rate- number of deaths in a certain amount of time Example- If 200 turtles die in a population in a year. The death rate is 200 turtles per year.

Changes in Population Size The Population Statement- If the birth rate is greater than the death rate in a population, the population with increase in size Birth rate > Death rate = population increase. If the death rate is greater than the birth rate in a population, the population with decrease in size Death rate > Birth rate = population decrease. Immigration and Emigration Immigration- Moving into a population Emigration- Moving out of a population

Limiting Factors Limiting Factor- an environmental factor that prevents a population from increasing Food- all animals need food, when food is scarce it is a limiting factor. Space Weather When factors are good, populations tend to increase. Carrying capacity- the largest population an environment can support.

5 Levels of Environmental Organization Organism- (one living thing) Population- (all of the same living thing *species*) Community- (all of the living things) Ecosystem- (all biotic and abiotic factors in an area) Biosphere- (all of the ecosystems in the world)