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POPULATIONS

POPULATIONS. POPULATIONS. Population : all the members of one species that occupy a certain area during a certain time. Ex. The population of bass in Lake Ontario in September of 2010 Biodiversity : the number of different types of species living in an ecosystem.

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POPULATIONS

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  1. POPULATIONS

  2. POPULATIONS • Population: all the members of one species that occupy a certain area during a certain time. • Ex. The population of bass in Lake Ontario in September of 2010 • Biodiversity: the number of different types of species living in an ecosystem. • Ex. A tropical rainforest is biodiverse. • Ex A ______________ is not biodiverse.

  3. DID YOU KNOW??? • As of Sept 22nd, 2010, Earth’s population is estimated to be about 6,872,897,353 !!!!! • By 2040, the population of Earth is estimated to reach about 9 billion people!

  4. POPULATION GROWTH PATTERNS • Four factors affect the size of a population: • Natality is the number of offspring of a species born in one year. • Immigration refers to the number of individuals of a species moving into an existing population. (these increase the population)

  5. POPULATION GROWTH PATTERNS • Mortality is the number of individuals of a species that die in one year. • Emigrationrefers to the number of individuals of a species moving out of an existing population. (these decrease the population size)

  6. CARRYING CAPACITY • The maximum size of a population that an • ecosystem can sustain is called its carrying • capacity. • Carrying capacity is determined by four factors. • Amount of available energy and materials • Predation • Competition • Amount of available space

  7. 1. Amount of Available Energy and Materials If a population grows too large, it will eventually crash when resources (nutrients, water, or energy) runs out. Ex. 2. Predation If a population grows too large, predation will increase, reducing the size of the population. (i.e. predators limit the size of the prey population) Ex.

  8. 3. Competition If resources become more scarce, members of a population must fight for their survival. This competition reduces the population by weaning out the weak or vulnerable members. There are two types of competition:

  9. TYPES OF COMPETITION • Intraspecific Competition – competition among members of the same species Ex. • Interspecific Competition– competition between members of different species Ex.

  10. 4. Space If a population grows too large, space will run out. Competition for space will reduce the population.If the density is too high, stress, disease, or parasites will reduce the population size Ex.

  11. Density-Dependent Factors These are factors that affect a population due to its size. Ex. a food shortage,

  12. Density-Independent Factors These are factors that affect a population regardless of its size. Ex. a flood,

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