dimorphism visually based thesis



For this assignment, we will be addressing an interesting subject in evolutionary biology: the question of sexual selection.  Very often, we see clear differences between sexes in many varieties of animals (including differences in size, coloration, behavior).  For example, see the duck species and peafowl  below:

This has been an area of inquiry dating back to Charles Darwin and Alfred Russel Wallace.  Dr. Melinda Weaver alluded to some of this in her own research in the introduction to module 4 (where she discussed her research with birds and coyotes).  For this assignment, you should find a case of ‘sexual dimorphism’ and write a short research paper delving into the evolutionary questions surrounding the differences between the sexes.  You should attempt to explain why it is that a dimorphism occurs between the sexes of the species you choose.

Questions you might think about:

  • Is there any kind of physical competition between members of one sex for access to the other?
  • Is the dimorphism visually based (color differences), size-based, or behavioral?
  • What does ‘parental investment theory’ have to say about the dimorphism you are documenting?  (which sex is being sexually selected and why?)
  • Are there any negative side-effects for the displays for males or females? (Do the displays sometimes result in mortality for the competitors?)
  • What is the larger ecological context in which this sexual selection occurs?  (what kind of environment is it occurring in?)

Things to include:

  • Your paper should be about two pages double-spaced.
  • Include at least three scholarly citations to back up your work
  • Include a photo of the species in question (ideally of male and female)

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