What do life tables and survivorship curves show us? Why would we want to make a survivorship curve or life table for an organism? Explain.

Governments around the world keep records of human birth and death rates not just for the overall population of a country but also for specific groups within it, broken down by age and sex. Often, this data is arranged in summary tables called life tables. Enterprising Insurance companies make good use of these life tables, taking the probability of death at a given age and using it to calculate insurance rates that, statistically, guarantee a tidy profit.

Ecologists often collect similar information for the species they study, but they don't do it to maximize profits! They do it to gain knowledge and, often, to help protect species. Take, for example, ecologists concerned about the endangered red panda. They might follow a group of red pandas from birth to death. Each year, they would record how many pandas had survived and how many cubs had been born. From this data, they could better understand the life history, or typical survival and reproduction pattern, of their red panda group.

What's the use of a life history? In some cases, ecologists are just plain curious about how organisms live, reproduce, and die. But there is also a practical reason to collect life history data. By combining birth and death rates with a "snapshot" of the current population-how many old and young organisms there are and whether they are male or female-ecologists can predict how a population is likely to grow or shrink in the future. This is particularly important in the case of an endangered species, like the red pandas in our example.