Fig. 1

Different types of survivorship curves. Humans, most mammals and model organisms such as Drosophila melanogaster and Caenorhabditis elegans have Type I survivorship curves with death primarily occurring in old age. Birds and some reptiles have a Type II survivorship curve, whereas trees and marine invertebrates have a Type III curve. Image credit: Population demography: Figure 5 by OpenStax College, Biology, CC BY 4.0