Population Ecology (Unit 7)

Bio 211--Unit 7

36 cards   |   Total Attempts: 188
  

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What is population?
A group of individuals of the same species that live in the same area at the same time
What is Population Ecology?
  • The study of how and why the number of individuals in a population changes over time and space
  • Focuses on the processes that CAUSE population change
Why study populations? (Besides learning about the natural history of particular species)--5 practical reasons
  1. Wildlife management
  2. Species Conservation
  3. Environmental Impact Assessment
  4. Understand disease epidemiology
  5. Life Insurance
What is Size?
Number of individuals
What is Range?
Geographic area in which a species/population occurs
What is density?
Number of individuals per unit area or volume
What is dispersion?
Pattern of spacing of individuals in a population
Population Size of Humans in:
  1. Ames
  2. Iowa
  3. US
  4. World
  • ~60,000
  • ~3,100,000
  • ~322,000,000 (USA! USA! USA!)
  • ~7,286,000,000
Estimating the Size of an Unknown Population (3)
  1. Direct Counting
  2. Random sampling and extrapolation
  3. Mark-recapture (usually for species that move quickly/often hidden from view)
What are different ways that Individuals are distributed spatially?
  1. Clumped
  2. Uniform
  3. Random
What does Clumped Dispersion suggest?
Positive interactions like:
  • Protection
  • Reproduction
  • Social Structure
  • Habitat variability
  • It is exhibited by most organisms b/c advantages outweigh disadvantages
What does Uniform Dispersion suggest?
  • Indicates negative interaction
  • Competition for resources
  • Direct antagonism/territoriality
What does Random Dispersion suggest?
  • Lack of strong intra-population interactions
  • Generally rare
  • Seen mostly in wind-dispersed plants or marine animals dispersed by ocean currents
Ecological Role of Krill (4)
  • Feed on algae that live under sea ice
  • Travel in HUGE numbers
  • A major food source for: Penguins, seals, albatross, fish, baleen whales
  • Krill population has decreased very dramatically due to less sea ice (also leading to the decline in population of penguins) and commercial harvest of krill, which affects the livelihood of whale populations and other creatures
Monarch Butterfly Decline....
Habitat loss & milkweed decline contribute to decreased numbers of monarchs