Biology ch 53

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Biology ch 53
2011-09-05 20:28:49

Ch 53: Population Ecology
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  1. population
    a group of individuaks of a single species living in the same general area
  2. population ecology
    explores how biotic and abiotic factors influence the density, distribution, size, and age structure of populations
  3. density
    • the number of individuals per unit area or volume.
    • increases by birthda/immigration
    • decreases by deaths/emmigration
  4. dispersion
    the pattern of spacing among individuals within the boundaries of the population
  5. most common dipersion pattern
  6. clumped dispersion
    individuals in patches, usually around a required resource
  7. uniform dispersion
    • animals that defend territories territories often show a uniform pattern
    • often the result of antagonistic behavior
  8. random dispersion
    • unpredictable spacing
    • not common; there is usually a reason for spacing
  9. demography
    the study of vital statistics of a population, especially birth and death rates
  10. life history
    • traits that affect an organism's schedulen of reproduction and survival
    • evolutionary, not conscious
  11. 3 variables of life history
    • when reproduction begins/age of sexual maturation
    • how often it reproduces
    • number of offsrping per reproduction
  12. exponential population growth
    • population growth under ideal conditions
    • any species is capable if resources are abundant
  13. carrying capacity
    the maximum population size that a certain environment can support at a particular time with no degradation of the habitat
  14. K-selection
    selection of life history traits that are sensitive to population density and carrying capacity
  15. r-selection
    selection for life history traits that maximize reproductive success
  16. density-dependant factors
    a death rate that rises as population density rises and a birth rate that falls as population density rises
  17. density-independant factors
    when a death rate does not change with increase in population density
  18. demographic transition
    • occurs when a population goes from high birth rates and high death rates to low birth rates and low death rates
    • takes about 150 years to complete- death rate falls first (increased medical care/sanitation). Falling birth rates take much longer, which delays it
  19. ecological footprint
    • examnies the total land and water are needed for all the resources a person consumes in a population
    • 1.7 hectares per person is sustainable
    • 10 hectares is average
  20. mark-recapture method
    • a sampling technique used to estimate the size of animal populations
    • Tag ("mark") individuals of a population. After these mix back in, they capture & tag more. The number of marked animals recaptured (x) divided by the total number recaptured (n) should equal the number of individuals marked and released in the first sampling (m) divided by the estimated population size
    • x/n = m/N
  21. territoriality
    the defense of a bounded physical space against encroachment by other individuals
  22. life table
    age-specific summaries of the survival pattern of a population
  23. cohort
    a group of individuals of the same age
  24. survivorship curve
    a plot of the proportion or numbers in a cohort still alive at each age
  25. reproductive table
    • fertility schedule
    • an age-specific summary of the reproductive rates in a population
  26. semelparity (big-bang reproduction)
    an organism produces all of their offspring in a single event
  27. iteroparity
    • adults produce offspring over many years
    • repeated reproduction
  28. logistic population growth
    the per capita rate of increase approaches zero as the carrying capacity is reached
  29. population dynamics
    focuses on the complex interactions between biotic and abiotic factors that cause variation in the size of populations
  30. metapopulation
    a group of spatitally separated populations of one species that interact through immigration and emigration.
  31. demographic transition
    a shift from rapid population growth in which birth rate outpaces death rate to zero population growth characterized by low birth rates and death rates
  32. age structure
    the relative number of individuals of each age in the population