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CHAPTER 4

CHAPTER 4. Population Ecology. 4-1: Population Dynamics. Populations are described as follows: Density Spatial distribution Growth rate Would an individual be considered a population?. Population Characteristics. Population density – number of organisms per unit of area

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CHAPTER 4

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  1. CHAPTER 4 Population Ecology

  2. 4-1: Population Dynamics • Populations are described as follows: • Density • Spatial distribution • Growth rate Would an individual be considered a population?

  3. Population Characteristics • Population density – number of organisms per unit of area • Spatial distribution • Dispersion (availability of resources is the most important factor) • Uniform • Clumped groups • Random Which of these dispersion types would be the easiest to predict?

  4. Population ranges • Only certain areas an organism can be located (i.e. Iiwi vs. Peregrine Falcon) • A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region. • Is it possible for a population to grow unchecked in size?

  5. Population – Limiting Factors • Density-independent factors • Population size does NOT matter • Usually abiotic • Ex. Weather • Density-dependent • Population size does matter • Usually biotic • Disease, parasites & competition

  6. Disease – outbreaks can be transmitted faster between individuals • Competition – when food and space become limited – fights will break out • Parasites – similar to disease

  7. Population Growth Rate • Natality vs. Mortality (most important) • Emigration vs. Immigration • Exponential growth model (geometric growth) • No limits • Lag phase (slow at beginning) • J shaped curve

  8. Logistic Growth Model • S shaped curve • Includes carrying capacity (population that can be supported by resources

  9. Reproductive Patterns • R-strategists • Small • Short life spans • Many offspring • Little to no energy spent on offspring • An adaptation to unstable environments

  10. Reproductive Patterns • K-strategists • Large • Long life spans • Not many offspring • Lots of energy spent on offspring • An adaptation to stable environments --Carrying capacity demonstration

  11. 4-1 HOMEWORK • Pretend you are living in the 16 and 17 hundreds. Create an advertisement (possible group of two) urging American settlers to move westward using knowledge gained from the section. Be creative!! • Using the 3 dispersion patterns – find organisms that are defined by each and explain why. • Create a comic strip from the perspective of any r-strategist • Give me a real world example of a density-independent factor and a density-dependent factor. Research this – none from discussion or book allowed.

  12. Section 2: Human Population

  13. http://www.pbs.org/wgbh/nova/worldbalance/ Human Population Growth • Demography – size, density, distribution, movement, birth & death rates • World population expected to double in about 53 years

  14. Technological advances • We have learned to alter our environment to change carrying capacity • Human population growth rate • Although raising in overall population, the percent of increase is dropping • Diseases such as AIDS • Voluntary population control

  15. Trends in Human Population Growth • Demographic transition (U.S. good example) • Zero population growth • Births + immigration = deaths + emigration • Age structure • Pre-reproductive (0-20) • Reproductive (20-45) • Post-reproductive (45 – 80+) • Human Carrying Capacity http://www.footprintnetwork.org/en/index.php/GFN/page/calculators/

  16. Trends in Human Population Growth • Demographic transition (U.S. good example)

  17. 4-2 Homework • Comprehension sentences for the chapter – due on day of test • Personal feeling about human population growth worldwide using at least 5 terms from the chapter

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