Levers and linkages: Mechanical trade-offs in a power-amplified system

Philip S.L. Anderson, Thomas Claverie, S. N. Patek

Research output: Contribution to journalArticlepeer-review


Mechanical redundancy within a biomechanical system (e.g., many-to-one mapping) allows morphologically divergent organisms to maintain equivalent mechanical outputs. However, most organisms depend on the integration of more than one biomechanical system. Here, we test whether coupled mechanical systems follow a pattern of amplification (mechanical changes are congruent and evolve toward the same functional extreme) or independence (mechanisms evolve independently). We examined the correlated evolution and evolutionary pathways of the coupled four-bar linkage and lever systems in mantis shrimp (Stomatopoda) ultrafast raptorial appendages. We examined models of character evolution in the framework of two divergent groups of stomatopods-"smashers" (hammer-shaped appendages) and "spearers" (bladed appendages). Smashers tended to evolve toward force amplification, whereas spearers evolved toward displacement amplification. These findings show that coupled biomechanical systems can evolve synergistically, thereby resulting in functional amplification rather than mechanical redundancy.

Original languageEnglish (US)
Pages (from-to)1919-1933
Number of pages15
Issue number7
StatePublished - Jul 2014
Externally publishedYes


  • Biomechanics
  • Kinematic transmission
  • Mantis shrimp
  • Phylogenetic comparative methods
  • Trade-offs

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • General Agricultural and Biological Sciences


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