Population DynamicsA group of organisms of the same species that occupy an area. One of the characteristics of living things is the ability to reproduce. If environmental conditions are “favorable” then the number of individuals in population should increase from one generation to the next.
3 Characteristics of Populations1) Geographic Distribution2) Density3) Growth Rate
4 Factors Effecting PopulationSize Births- individuals born each year Deaths- that die each year individuals Immigration – Movement of individuals INTO a population Emigration- Movement of individuals OUT of a population
Population Size-Growth Rate Birth rate- # individuals born Death rate- # individuals die Immigration- # of individuals move in Emigration- # of individuals move out IF: BR + I = DR + E Equilibrium BR + I > DR + E Increasing BR + I < DR + E Decreasing
Biotic Potential Under “favorable” conditions, a species may reach its biotic potential. Highest reproduction rate possible for a species under “ideal” conditions. Ex) Houseflies: Lay over 100 eggs Can reproduce at 1 month After 7 generations, 1 fly =15 billion flies!!!
Exponential Growth Populations size increases dramatically over time. Occurs: when resources (food) are abundant Shape: J
Logistic Growth A population begins with a period of slow growth followed by a brief period of exponential growth before leveling off at a stable size Occurs: because resources are limited Shape: S Environmental resistance limits size of a population. Real population growth looks like this.3 Phases: lagging, exponential, equilibrium
Factors Effect Growth Rate Sizeof Population factors” stop population“limiting from reaching biotic potential. (keeping the population in check)The number of individuals in a population for a certain area is called population density.
Carrying CapacityMax # of individuals of a species that the environment can normally &consistently support.Changes as theenvironmentchanges.
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