Head shape modulates diversification of a classic cichlid pharyngeal jaw innovation

Edward D. Burress, Milton Tan, Peter C. Wainwright

Research output: Contribution to journalArticle

Abstract

Functional innovations are often invoked to explain the uneven distribution of ecological diversity. Innovations may provide access to new adaptive zones by expanding available ecological opportunities and may serve as catalysts of adaptive radiation. However, diversity is often unevenly distributed within clades that share a key innovation, highlighting the possibility that the impact of the innovation is mediated by other traits. Pharyngognathy is a widely recognized innovation of the pharyngeal jaws that enhances the ability to process hard and tough prey in several major radiations of fishes, including marine wrasses and freshwater cichlids. We explored diversification of lower pharyngeal jaw shape, a key feature of pharyngognathy, and the extent to which it is influenced by head shape in Neotropical cichlids. While pharyngeal jaw shape was unaffected by either head length or head depth, its disparity declined dramatically with increasing head width. Head width also predicted the rate of pharyngeal jaw evolution such that higher rates were associated with narrow heads. Wide heads are associated with exploiting prey that require intense processing by pharyngeal jaws that have expanded surfaces for the attachment of enlarged muscles. However, we show that a wide head constrains access to adaptive peaks associated with several trophic roles. A constraint on the independent evolution of pharyngeal jaw and head shape may explain the uneven distribution of ecological diversity within a clade that shares a major functional innovation.

Original languageEnglish (US)
Pages (from-to)693-706
Number of pages14
JournalAmerican Naturalist
Volume194
Issue number5
DOIs
StatePublished - Nov 1 2019

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cichlid
jaws
innovation
adaptive radiation
Labridae
catalysts
marine fish
muscle
catalyst
muscles
fish

Keywords

  • Adaptive landscape
  • Adaptive radiation
  • Functional constraint
  • Morphology
  • Pharyngognathy

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Cite this

Head shape modulates diversification of a classic cichlid pharyngeal jaw innovation. / Burress, Edward D.; Tan, Milton; Wainwright, Peter C.

In: American Naturalist, Vol. 194, No. 5, 01.11.2019, p. 693-706.

Research output: Contribution to journalArticle

Burress, Edward D. ; Tan, Milton ; Wainwright, Peter C. / Head shape modulates diversification of a classic cichlid pharyngeal jaw innovation. In: American Naturalist. 2019 ; Vol. 194, No. 5. pp. 693-706.
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