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Those Who Wish to Sing Always Find a Song

Call Loss and Reinvention in Hawaiian Crickets

By Justin W. Merry

Those Who Wish to Sing Always Find a Song



This interrupted case study examines the evolution of cricket stridulation in the Hawaiian Islands, where a silent, non-stridulating phenotype of Teleogryllus oceanicus has evolved and spread throughout Hawaiian populations in just over a decade in response to predation by a parasitoid fly that finds crickets to prey upon via their calls. Students learn how natural selection works and use simple Mendelian crosses to uncover the genetic mechanism driving the change. Finally, they are introduced to the most recent development in this evolutionary case study, the appearance of a new phenotype that produces a purr-like call. Students evaluate data that tests the hypothesis that this new call is more attractive to female crickets than the silent phenotype while still avoiding predation by the flies better than the ancestral call type. Originally designed as a review of natural selection fundamentals and hypothesis testing for an undergraduate course on animal behavior, it is similarly suited for courses in evolution, ecology, introductory biology, or advanced high school biology.


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  • Explain the role of variation, heritability, and reproductive consequences in how natural selection drives the evolution of specific traits.
  • Apply the concept of natural selection to explain why T. oceanicus crickets evolved the flatwing morphs in the face of predation by a parasitoid fly.
  • Test between alternative hypotheses for Mendelian inheritance patterns by working out crosses and comparing predicted ratios to actual results.
  • Utilize quantitative behavioral data to test the hypothesis that the new purring phenotype is favored because it allows for clandestine communication between crickets in the presence of the parasitoid.


Natural selection; evolution; arthropods; crickets; stridulation; evolution of novelty; parasitoids; predation; communication; mate choice; Hawaii; Mendelian inheritance; cross; Punnett square


Subject Headings

Biology (General)
Evolutionary Biology
Genetics / Heredity


High school, Undergraduate lower division















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