Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms

Bruno A. Buzatto, Huon L. Clark, Joseph L. Tomkins

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite Rhizoglyphus echinopus. Large ‘fighter’ males have a thick and sharply terminating pair of legs used to kill rival males, while small ‘scrambler’ males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters diverged in relative leg thickness after six generations; assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic diversity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independently respond to selection. We therefore question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.

Original languageEnglish
Article number20180335
Number of pages7
JournalProceedings of The Royal Society of London Series B: Biological Sciences
Issue number1879
Publication statusPublished - 30 May 2018
Externally publishedYes


  • Alternative reproductive tactics
  • Conditional strategy
  • Intralocus tactical conflict
  • Intrasexual dimorphism
  • Polyphenism
  • Rhizoglyphus echinopus


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