Introduction

We represent age structure information in standardized form in a life table. A life table shows the numbers of individuals in each age class as well as a set of age-specific parameters such as mortality, reproduction, and life expectancy. Survivorship often changes over the lifespan of the organism. We visually represent these changes with survivorship curves in which we plot the log number surviving as a function of age (see Figures 8.11 and 8.12 on the following page).

Learning Goals

After reading your text and completing this exercise, you should be able to:

• Understand the variables that comprise a life table.
• Generate a survivorship curve from life table information.
• Explain the differences among Type I , Type II, and Type III survivorship curves.