Survivor Curves and Exponential Growth

a plot of the proportion or numbers in a cohort still alive at each age.

survivorship curve

is flat at the start, reflecting low death rates during early and middle life, and then drops steeply among older age-groups.

Type I curve

are intermediate, with a constant death rate over the organism’s life span.

Type II curves

drops sharply at the start, reflecting very high death rates for the young, but flattens out as death rates decline for those few individuals that survive the early period die-off.

type III curve

forms a J-shaped curve when population size is plotted over time.

exponential population growth

as the maximum population size that a particular environment can sustain.

carrying capacity

population growth approaches zero as the size of the population nears the carrying capacity.

logistic population growth