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PLoS Biol. 2015 Apr 28;13(4):e1002123. doi: 10.1371/journal.pbio.1002123. eCollection 2015 Apr.

Convergent evolution of mechanically optimal locomotion in aquatic invertebrates and vertebrates.

Author information

1
Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America.
2
Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America.
3
Department of Mechanical Engineering, Northwestern University, Evanston, Illinois, United States of America; Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America; Department of Neurobiology, Northwestern University, Evanston, Illinois, United States of America.

Abstract

Examples of animals evolving similar traits despite the absence of that trait in the last common ancestor, such as the wing and camera-type lens eye in vertebrates and invertebrates, are called cases of convergent evolution. Instances of convergent evolution of locomotory patterns that quantitatively agree with the mechanically optimal solution are very rare. Here, we show that, with respect to a very diverse group of aquatic animals, a mechanically optimal method of swimming with elongated fins has evolved independently at least eight times in both vertebrate and invertebrate swimmers across three different phyla. Specifically, if we take the length of an undulation along an animal's fin during swimming and divide it by the mean amplitude of undulations along the fin length, the result is consistently around twenty. We call this value the optimal specific wavelength (OSW). We show that the OSW maximizes the force generated by the body, which also maximizes swimming speed. We hypothesize a mechanical basis for this optimality and suggest reasons for its repeated emergence through evolution.

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PMID:
25919026
PMCID:
PMC4412495
DOI:
10.1371/journal.pbio.1002123
[Indexed for MEDLINE]
Free PMC Article

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