Survivorship curves compare how mortality is distributed across the lifespan of different species. Starting from 1000 individuals, the log scale allows all three types to be compared on one graph.
Key Concepts
• Type I: low mortality until old age — parental care, few offspring (K-strategists)
• Type II: constant death rate at all ages — straight line on log scale
• Type III: very high early mortality; survivors live long — many small offspring (r-strategists)
• Most real species fall between these three idealised types
• Used to construct life tables for population ecology and conservation biology