Do now activity #4 What is commensalism? Give an example. What is mutualism? Give an example. What is parasitism? Give an example. What is a symbiotic relationship?

Section 8-2: Populations Essential Question: How do characteristics of a population shape the population over time? Learning Target Explain how environmental factors affect carrying capacity of a population. Analyze population data and explain how age structure, growth rate, and population density will impact the population over time. Section 8-2: Populations

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overview Population: a group of the same species in the same area cyclins Population: a group of the same species in the same area

overview cyclins Density, age groups, and growth rates are used to describe populations.

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Population Density is the number of individuals in an area.

Population density Geographic distribution (range) describes the size of the area an organism lives in.

Population density This can vary in size from a few cm3 to millions of km2.

Population density Population density is calculated by this formula: number of individuals in the area Geographic distribution Example: 100 antelope inhabiting 1 km2 area of land would be: 100 antelope 1 km2

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The ages of individuals in a population determine the age groups. Phosphorus is necessary for organisms DNA & RNA ATP Stored mostly in rocks, soil and ocean sediment. Not in the atmosphere Plants absorb phosphorus from soil Phosphorus then moves through the food web Dead plants and animals decompose, the phosphorus goes back into the soil.

Age groups Old people don’t have babies U.S. Life Expectancy = Men: 75/Women:80 A high % of young people means a greater potential for rapid growth. Phosphorus is necessary for organisms DNA & RNA ATP Stored mostly in rocks, soil and ocean sediment. Not in the atmosphere Plants absorb phosphorus from soil Phosphorus then moves through the food web Dead plants and animals decompose, the phosphorus goes back into the soil.

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Growth rate Growth rate is how fast the number of individuals increases or decreases in a population.

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Population size Four factors affect population size # of births # of deaths Immigration (moving in) Emigration (moving out) ________________________________________________________________________________________________________ (# of births + immigration #) – (# of deaths + emigration #) = POPULATION GROWTH Population size the year before + Population growth = CURRENT POPULATION SIZE Phosphorus is necessary for organisms DNA & RNA ATP Stored mostly in rocks, soil and ocean sediment. Not in the atmosphere Plants absorb phosphorus from soil Phosphorus then moves through the food web Dead plants and animals decompose, the phosphorus goes back into the soil.

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Exponential growth Exponential Growth Occurs when a population reproduce at a constant rate. Creates a J-shaped curve There has to be unlimited resources. Food, Water. Shelter

Logistical growth Growth - birth > death Stationary - birth = death Decline - birth < death Logistic growth Accounts for the influence of limiting factors. -it has an S-curve The carrying capacity is the # of individuals the environment can support.

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