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Populations

Populations. Rates That Affect Population Size. Natality- the birth rate; the number of births over time Mortality- the death rate; the number of deaths over time. Rates That Affect Population Size.

denise-dennis
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Populations

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  1. Populations

  2. Rates That Affect Population Size • Natality- the birth rate; the number of births over time • Mortality- the death rate; the number of deaths over time

  3. Rates That Affect Population Size • Immigration- the rate of individuals entering the population from a different population; the number of individuals entering over time • Emigration- the rate of individuals leaving a populations to go to a different population; the number of individuals leaving a population

  4. Population Growth • Two Types of Growth: • Exponential • Logistic

  5. Exponential Growth • Occurs when the individuals in a population reproduce at a constant rate • Under ideal conditions with unlimited resources, a population will grow exponentially

  6. Exponential Growth J-Curve

  7. Logistic Growth • Occurs when a population's growth slows or stops following a period of exponential growth

  8. Logistic Growth S-Curve

  9. Carrying Capacity- the maximum population size that environment can sustain. • Usually determined by a limiting factor • As resources become less available the growth of a population slows or stops.

  10. New or early populations show exponential growth • Old, stable populations show no growth, but stay near the carrying capacity of the environment

  11. What happens if a population exceeds its carrying capacity?

  12. If a population exceeds the carrying capacity of its environment, the carrying capacity decreases

  13. Human Population • Is the human population growing exponentially or logistically?

  14. Niches and Communities • Niche - range of physical and biological conditions in which a species lives and the way the species obtains what it needs to survive and reproduce. • Different Factors: • Tolerance – ability to survive and reproduce under a range on environmental circumstances.

  15. Tolerance Graph

  16. Niche cont. • Resources – food, water, nutrients, etc • Physical – abiotic factors • Biological – biotic factors • Competition – exactly what you would think • Competitive Exclusion Principle – no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time.

  17. Predator-Prey Relationships • Predation – interaction in which one animal (predator) eats another animal (prey) • Predators affect the size of prey populations within a community and determine the places where the prey can live. • Herbivory – Same concept at predation just with plants

  18. Predator-Prey Graph

  19. Symbioses • Two creatures living in harmony and helping each other survive. • Mutualism – both benefit (Clown fish – Anemone) • Parasitism – one organisms lives inside or on another organisms and harms it (Tapeworms) • Commensalism – one organism benefits and the other is neither harmed nor helped. (Barnacles and Whales)

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