Journal of Molecular Evolution

, Volume 73, Issue 1–2, pp 1–9 | Cite as

Positive Darwinian Selection Drives the Evolution of the Morphology-Related Gene, EPCAM, in Particularly Species-Rich Lineages of African Cichlid Fishes



The study of genetic evolution within the context of adaptive radiations offers insights to genes and selection pressures that result in rapid morphological change. Cichlid fishes are very species-rich and variable in coloration, behavior, and morphology, and so provide a classical model system for studying the genetics of adaptive radiation. In this study, we researched the evolution of the epithelial cell adhesion molecule (EPCAM), a candidate gene for the adaptive evolution of morphology broadly, and skin development specifically, in fishes. We compared EPCAM gene sequences from a rapidly speciating African cichlid lineage (the haplochromines), a species-poor African lineage (Nile tilapia Oreochromis niloticus), and a very young adaptive radiation in the Neotropics (sympatric crater lake Midas cichlids, Amphilophus sp.). Our results, based on a hierarchy of evolutionary analyses of nucleotide substitution, demonstrate that there are different selection pressures on the EPCAM gene among the cichlid lineages. Several waves of positive natural selection were identified not only on the terminal branches, but also on ancestral branches. Interestingly, significant positive or directional selection was found in the haplochromine cichlids only but not the comparatively species-poor tilapia lineage. We hypothesize that the strong signal of selection in the ancestral African cichlid lineage coincided with the transition from riverine to lacustrine habitat. The two neotropical species for which we collected new sequence data were invariant in the EPCAM locus. Our results suggest that functional changes promoted by positive Darwinian selection are widespread in the EPCAM gene during African cichlid evolution.


Positive Darwinian selection Epithelial cell adhesion molecule Adaptive radiation 



We thank the participants of the Konstanz Ecology and Evolution discussion group, S. Kuraku, and two anonymous reviewers for comments that improved the manuscript. This work was financially supported by a doctoral stipend from University of Konstanz to S.Fan, an NSERC fellowship and a University of Konstanz Young Scholar’s Award to K.R. Elmer and the Deutsche Forschungsgemeinschaft and the University of Konstanz to A. Meyer.

Supplementary material

239_2011_9452_MOESM1_ESM.doc (63 kb)
Supplementary material 1 (DOC 63 kb)


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© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Lehrstuhl für Zoologie und Evolutionsbiologie, Department of BiologyUniversity of KonstanzConstanceGermany

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