Population Ecology

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Author:
HappyJedi7
ID:
147879
Filename:
Population Ecology
Updated:
2012-04-16 01:04:12
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Bio 244 lab
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Description:
Unit 24 (last unit!!!!! whooooo!!!)
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  1. ecology
    • the study of interactions among living organisms and the interactions with their environment
    • the study of the environmental factors and evolutionary forces that influence life histories, distribution and abundance of organisms
    • the study of the function and structure of populations, communities, and ecosystems
  2. organisms
    • fundamental unit
    • a single living individual of one species
    • evolutionary processes work at the individual level
  3. populations
    • consists of all individuals of one species found in a defined area
    • longer-lived than an individual organism
    • have emergent properties (eg, rates, patterns)
  4. emergent properties
    parameters are not present at lower levels
  5. species
    all individuals in an area that potentially can mate and produce fertile offspring (biological species concept)
  6. habitat
    the place or environment in which the individual or species resides
  7. linear (arithmetic) growth
    • increases at a linear rate over time (eg, 1, 2, 3, 4, 5...)
    • not observed in many populations over time
  8. exponential growth
    • the phase in which the population can initially grow at a rapid pace
    • in the absence of competitors, disease, weather, preddators
    • in the presence of lots of food
  9. the differential equation creates a j-shaped or exponential curve


    • (dt) = change in time
    • (dN) = change in population time
    • N = initial population size
    • r = reproductive rate per individual (growth rate of population)
    • ignores immigration and emigration
  10. r is determined by:
    b - d = r

    • b = birth rate
    • d = death rate
    • ignores immigration and emigration
  11. growth possibilities
    • r=0 : no growth (b=d), no change in N
    • r<0 : negative growth (b<d), decrease in N
    • r>0 : positive growth (b>d), increase in N
  12. logistic growth
    • population size does not continue to increase exponentially, but it tends to level off after a certain population size has been reached
    • limits to growth imposed by environment, some resources becoming limiting
  13. logistic growth equation


    • [rate of change in population size over time] = [rate of per capita population growth]x[population density]x[unutilized capacity for population growth]
    • K=carrying capacity (constant, maximal, sustainable population size)
    • is an S-shaped, sigmoidal graph
  14. when N = K ......
    • dN/dt = 0
    • growth rate r = 0
    • b = d
  15. Populations tend to...
    ...level off or fluctuate around a certain size.
  16. environmental resistance
    factors that limit the exponential growth of a population
  17. Competition coefficients alpha and beta are used to...
    ... determine the impact of interspecific competition. Both species compete for the same resources.
  18. competitive exclusion
    if the species compete for long enough, the better competitor can drive the other species into extinction locally
  19. In any one habitat, two species cannot...
    ...coexist in the same niche (functional role in a community).

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