HD

3.3 Survivor-ship Curves 

  • Survivor-ship Curve: line that shows the survival rate of a cohort (group of same-aged individuals) in a pop. from birth to death 
    • Faster drop in line = quicker die-off of individuals
    • Slower drop in line = longer avg. lifespan

Type I, II, and III

Type I (mostly K-selected)

  • High survivorship early in life due to high parental care
  • High survivorship in mid life due to large size & defensive behavior
  • Rapid decrease in survivor-ship in late life as old age sets in
    • Ex: most mammals

Type II (in between r & K)

  • Steadily decreasing survivor-ship throughout life 

Type III (mostly r-selected)

  • High mortality (low survivor-ship) early in life due to little to no parental care 
  • Few make it to midlife; slow, steady decline in survivor-ship in mid life
  • Even fewer make it to adulthood; slow decline in survivor-ship in old age
  • Ex: insects, fish, plants