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REDUCTION OF THE PECTORAL SPINE AND GIRDLE IN DOMESTICATED CHANNEL CATFISH IS LIKELY CAUSED BY CHANGES IN SELECTION PRESSURE
Author(s) -
Fine Michael L.,
Lahiri Shweta,
Sullivan Amanda D. H.,
Mayo Mark,
Newton Scott H.,
Sismour Edward N.
Publication year - 2014
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12379
Subject(s) - pectoral girdle , biology , catfish , ictalurus , spine (molecular biology) , appendicular skeleton , domestication , anatomy , micropterus , predation , ictaluridae , zoology , fishery , ecology , fish <actinopterygii> , microbiology and biotechnology
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.