Evol Ecol Res 7: 303-324 (2005)     Full PDF if your library subscribes.

Trophic morphology, feeding performance and prey use in the polymorphic fish Herichthys minckleyi

C. Darrin Hulsey,1,2* Dean A. Hendrickson3 and Francisco J. García de León4

1Center for Population Biology and Department of Evolution and Ecology, University of California, Davis, CA, USA,  2Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA,  3Section of Integrative Biology, University of Texas, Austin, TX, USA and  4Laboratorio de Biología Integrativa, Instituto Tecnológico de Cuidad Victoria, Tamaulipas, Mexico

Address all correspondence to C. Darrin Hulsey, Ecology and Evolutionary Biology, University of Tennessee at Knoxville, 569 Dabney Hall, Knoxville, TN 37996, USA.
e-mail: chulsey@utk.edu

ABSTRACT

Question: How does pharyngeal jaw morphology influence feeding performance and prey use in the trophically polymorphic cichlid fish Herichthys minckleyi ?

Organism: Herichthys minckleyi exhibits two discrete pharyngeal jaw morphologies. Molariforms possess flattened teeth and enlarged pharyngeal muscles, whereas papilliforms exhibit more gracile jaws, pointed teeth and smaller muscles.

Data: We combined anatomy, experiments, diet analyses and a review of molluscivory to examine the relationships between morphology, feeding performance and prey use.

Conclusions: Handling time differed only slightly between morphotypes. Papilliforms shredded plants more finely than molariforms, and only molariforms readily crushed snails. Molariforms employed their maximum force-producing capabilities to crush snails in the wild. Comparisons with other molluscivorous fish suggested that the amount of hard-shelled prey molariform H. minckleyi ingest is not unusual, but its pharyngeal muscle mass and the force used to crush snails are extreme.

Keywords: body size, Cichlidae, co-evolution, Cuatro Ciénegas, Hydrobiidae, maximum performance.

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