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11.2 Changes in Population Size. Measuring Population Change Four basic processes that change the size of all population Immigration – movement of individuals into a population Emigration – movement of individuals out of population Birth Death. Population change can be calculated as:
E N D
Measuring Population Change • Four basic processes that change the size of all population • Immigration – movement of individuals into a population • Emigration – movement of individuals out of population • Birth • Death
Population change can be calculated as: N = population size B = Birth D = death I = immigration E = Emigration
For most populations, immigration is equaled by emigration, therefore calculating the Change in Population is as: N = B - D
The growth rate then is calculated as: • Per Capita Growth Rate:
Population Growth Models • Biotic potential (highest possible per capital growth rate) is determined by factors related to fecundity • # of offspring per reproductive cycle • # of offspring that survive to reproduce • Age of sexual maturity • # of offspring produced in life span • Life span of individual
A population growing at its biotic potential experiences exponential growth
A population growing in limited environment would experience a carry capacity
R selected strategy live close to their biotic potential • Short life span • Sexually mature young • Large broods • Little or no parental care
K selected strategy live close to their carry capacity • Relatively long life span • Sexually mature late in life • Less offspring per reproductive cycle • Higher parental care Pg 519 #1-10