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Bell Ringer:

Bell Ringer:

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  1. Bell Ringer: • 3 Factors that affect population size: • Number of Births • Number of Deaths • Number of individuals entering or leaving a population (immigration vs. emigration) • Increase: births and immigration • Decrease: deaths and emigration

  2. Limits to GrowthSection 5-2 Flora

  3. Limits to Growth • Limiting Factor – factor that causes population growth to decrease • Ex: • Competition • Predation • Parasitism • Human disturbances • Climate Extremes

  4. Types of Factors • Density-dependent • Density-independent

  5. Density-Dependent Factors • DDLF – limiting factor that depends on population size • These factors become limiting only when the population density reaches a certain level • Usually occurs when population is large and dense • Ex: competition, predation, parasitism, disease

  6. Competition • Can occur within species or between different species • More individuals leads to depleted resources • Less individuals leads to less competition

  7. Predation • Populations are often controlled by predation • Predator prey relationships – mechanism of population control in which a population is regulated by predation • Ex: page 126; figure 5-7

  8. Parasitism and Disease • Organisms are similar to predators • Take nourishment at the expense of their hosts

  9. Density-Independent Factors • Affect all populations in similar ways regardless of population size • Ex: • Weather • Natural disaster • Season cycles • Human activities ** Populations often show rapid declines in these situations