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Population dynamics. Exponential Growth. Exponential growth of a population of organisms occurs when the # of organisms rises at an ever-increasing rate. Population Growth of Houseflies. 1 million. 500,000. Population size. 100. One year.
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Exponential Growth Exponential growth of a population of organisms occurs when the # of organisms rises at an ever-increasing rate.
Population Growth of Houseflies 1 million 500,000 Population size 100 One year
What are some things that prevent populations from growing exponentially?
Carrying Capacity The number of organisms that a particular environment can support over an indefinite period of time. • Births will exceed deaths until carrying capacity is reached
Carrying capacity Carrying capacity Number of Yeast Cells Time (hours)
Limiting factors • Density-dependent • Density-independent • Predation
Limiting factors • Density-dependent • Have an increasing effect as population increases • Ex. Disease, parasites, competition, crowding & stress • Density-independent • Affects all populations, regardless of their density • Usually abiotic factors: ex. storms, floods, temp, fire • Predation – keeps population size within limits (density-dependent)
Practice Classify each of the following as either density-dependent or density-independent. • Intense heat wave • Large population of caterpillars infected with wasp larvae parasites • Overpopulation of an organism • Clear cutting of a forest to build a shopping center.
Exotics Species living in an area to which they are not native Can be introduced accidentally or on purpose Ex. Sika from Asia brought to South TX
How do you think introducing Sika into the population would affect the native population of deer?