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Jumping Spider Dances:
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Jumping Spider Dances: Summary

Let's summarize what's been covered.

  • Sexual selection is a form of natural selection in which individuals of the same sex differ in their ability to gain matings or choose partners.
  • By definition, males produce many tiny gametes (sperm) whereas females produce few large gametes (eggs).
  • Hence, females devote a greater proportion of their resources to each egg than males do to each sperm.
  • Bearing and caring for young often add to the cost of each gamete for females.
  • Usually, the male maximizes his fitness by gaining as many matings with as many different females as possible.
  • Females usually maximize their fitness by choosing the best sperm donor.
  • The "operational sex ratio" is the ratio of fertile, available females to males (as opposed to all individuals in the population).
  • In nature, operational sex ratios are often male-biased.
  • This means that males compete for females, and females can choose among males.
  • In jumping spiders, males compete with colorful ornamentation and complex dance behaviors. Females are usually drab in coloration.
  • Research at the University of Arizona has shown that populations of one species isolated on mountaintops are evolving into different species through sexual selection on male appearance and behavior.

End of Jumping Spiders module.

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