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Article first published online: 20 MAR 2014

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March 2015


Locked pectoral spines of the Channel Catfish Ictalurus punctatus more than double the fish's width and complicate ingestion by gape-limited predators. The spine mates with the pectoral girdle, a robust structure that anchors the spine. This study demonstrates that both spine and girdle exhibit negative allometric growth and that pectoral spines and girdles are lighter in domesticated than in wild Channel Catfish. This finding could be explained by changes in selection pressure for spine growth during domestication or by an epigenetic effect in which exposure to predators in wild fish stimulates pectoral growth. We tested the epigenetic hypothesis by exposing domesticated Channel Catfish fingerlings to Largemouth Bass Micropterus salmoides predators for 13 weeks. Spines and girdles grow isometrically in the fingerlings, and regression analysis indicates no difference in proportional pectoral growth between control and predator-exposed fish. Therefore a change in selection pressure likely accounts for smaller pectoral growth in domesticated Channel Catfish. Decreasing spine growth in older fish suggests anti-predator functions are most important in smaller fish. Additionally, growth of the appendicular and axial skeleton is controlled differentially, and mechanical properties of the spine and not just its length are an important component of this defensive adaptation.


© 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution. This is the peer reviewed version of the following article: Fine, M. L., Lahiri, S., Sullivan, A. D. H., Mayo, M., Newton, S. H. and Sismour, E. N. (2014), REDUCTION OF THE PECTORAL SPINE AND GIRDLE IN DOMESTICATED CHANNEL CATFISH IS LIKELY CAUSED BY CHANGES IN SELECTION PRESSURE. Evolution, 68: 2102–2107. doi: 10.1111/evo.12379, which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archiving.

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VCU Biology Publications