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Life Tables, Darwin’s Finches, and the Dynamics of Small Island Populations

By Whitley R. Lehto, Shannon M. Murphy, Mayra C. Vidal, Robin M. Tinghitella

Life Tables, Darwin’s Finches, and the Dynamics of Small Island Populations



This case study uses Darwin’s finches to teach students about life tables. Life tables are tables of statistics that relate to life expectancy and reproductive output for a population of organisms. Students are asked to tabulate traditional life table values like those obtained by evolutionary biologists Peter and Rosemary Grant, who study the dynamics of finch populations in the Galapagos Islands. Students next compare the survival of two different finch species as well as groups of the same species tracked at different time points. They then interpret and integrate information in multiple forms (numerical, graphical, and written) to address ecological and evolutionary problems. For instance, students produce their own survivorship curve from calculated life table values and, together with graphical data on annual rainfall, speculate on the relationship between rainfall and finch survival. Students also calculate reproductive rates and generation times of the finches and integrate the concepts of effective population size and genetic drift to discuss the dynamics of small populations. The case works well with any class size and is appropriate for majors in biology or ecology courses.


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  • Tabulate typical life table values including: proportion surviving, proportion dying, mortality rate, and net reproductive rate.
  • Interpret life table values in an ecological application.
  • Develop hypotheses based on life table values.
  • Generate a survivorship curve (including typical graph components).
  • Interpret and integrate multiple forms of information (graphical, numerical, and written) to address novel problems.


Life table; demography; population dynamics; proportion surviving; net reproductive rate; mortality rate; Galapagos Islands; Darwin’s finches; Peter Grant; Rosemary Grant


Subject Headings

Biology (General)
Evolutionary Biology


Undergraduate lower division, Undergraduate upper division



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Directed, Discussion, Interrupted



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