Final answer:
A survivorship curve is a graphical representation used by population ecologists to show the number of individuals surviving at different age intervals over time. There are three types of curves: Type I with low early age mortality, Type II with consistent mortality and Type III with high juvenile mortality but lower rates for survivors into older age.
Step-by-step explanation:
A survivorship curve plots the probability at birth of surviving to any given age (lx) against time or age class (x). Survivorship curves are used by population ecologists to graph the number of individuals surviving at each age interval over time, with data often compiled from a life table. These curves are crucial for comparing the life histories of different populations and understanding mortality patterns within a species.
There are three types of survivorship curves:
- Type I curve, where mortality is lower at younger ages and increases significantly in older individuals. Humans and many mammals exhibit this type of curve.
- Type II curve presents a relatively constant mortality rate throughout an organism's life span. Many birds are examples of this intermediate type of survivorship curve.
- Type III curve, in which there is high mortality at young ages, but individuals who survive past this stage are likely to live for a longer period. This type can be seen in organisms like trees and marine invertebrates, which produce a large number of offspring with minimal parental care.
Each curve provides insight into the reproductive strategies and environmental pressures faced by different organisms within their ecosystems.