Table of Contents
International Journal of Evolutionary Biology
Volume 2012, Article ID 538146, 9 pages
http://dx.doi.org/10.1155/2012/538146
Research Article

More than Meets the Eye: Functionally Salient Changes in Internal Bone Architecture Accompany Divergence in Cichlid Feeding Mode

1Department of Biology, University of Massachusetts Amherst, 611 North Pleasant Street, Amherst, MA 01003, USA
2School of Biological Sciences, Washington State University Tri-Cities, 2710 Crimson Way, Richland, WA 99354, USA
3Institute for Human Performance, Department of Orthopedic Surgery, SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210, USA

Received 17 January 2012; Accepted 14 March 2012

Academic Editor: Tetsumi Takahashi

Copyright © 2012 R. Craig Albertson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

African cichlids have undergone extensive and repeated adaptive radiations in foraging habitat. While the external morphology of the cichlid craniofacial skeleton has been studied extensively, biomechanically relevant changes to internal bone architecture have been largely overlooked. Here we explore two fundamental questions: (1) Do changes in the internal architecture of bone accompany shifts in foraging mode? (2) What is the genetic basis for this trait? We focus on the maxilla, which is an integral part of the feeding apparatus and an element that should be subjected to significant bending forces during biting. Analyses of CT scans revealed clear differences between the maxilla of two species that employ alternative foraging strategies (i.e., biting versus suction feeding). Hybrids between the two species exhibit maxillary geometries that closely resemble those of the suction feeding species, consistent with a dominant mode of inheritance. This was supported by the results of a genetic mapping experiment, where suction feeding alleles were dominant to biting alleles at two loci that affect bone architecture. Overall, these data suggest that the internal structure of the cichlid maxilla has a tractable genetic basis and that discrete shifts in this trait have accompanied the evolution of alternate feeding modes.