by
Kari Benson
School of Sciences
Lynchburg College, Lynchburg, VA
This is an interrupted case where students work in small groups on behavioral data they are given in a piecemeal fashion and interpret the data with respect to evolutionary biology. [Editor’s Note: For a description of the interrupted case method, see the prologue to “Mom Always Liked You Best,” another case on our website.]
This case is suitable for courses in behavior, evolution, and ecology. Sections of it could be used in an introductory biology course if evolution and ecology get sufficient coverage. I have used the case in both an introductory biology course and an upper-level animal behavior course to reinforce an understanding of kin selection and to encourage students to consider the levels-of-selection controversy.
The case was inspired by work done by Paul Sherman (1977). Sherman discovered that the apparently altruistic behavior of alarm calling in Belding’s ground squirrels is, in fact, nepotism. That is, it is not evolutionarily stable to assist non-related individuals at a cost to yourself (without sufficient opportunity for reciprocation or group selection); rather, evolutionarily speaking, it is beneficial to aid those individuals that share your genes by common descent, even if they are not your direct offspring.
The case requires that students understand the basic principles of natural selection. Students should recognize that selection requires fitness benefits to some heritable trait. Thus, natural selection results in differential success of specific alleles in a population. Students must recognize that there are fitness benefits to certain alleles if they are to conclude that genes shared by common descent can confer a fitness advantage to an individual. It may also be helpful to emphasize that natural selection acts on phenotypes but results in changes in allele frequencies in a population.
Upon completion of the case, students will have developed testable hypotheses and interpreted graphical information. In addition, they will understand that:
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Acknowledgements: This case was developed with support from The Pew Charitable Trusts as part of the Case Studies in Science Workshop held at the University at Buffalo, State University of New York, on June 10–14, 2002.
Image Credit: Photo of Belding’s ground squirrels by Don Baccus (dhogaza@pacifier.com), © 1999. Used with permission.
Date Posted: 03/08/04 nas. Last updated 11/29/04.
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Originally published at http://www.sciencecases.org/kin_selection/kin_selection_notes.asp
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