Phenotypical variability affecting the commercial value of the stalked barnacle Pollicipes pollicipes: No evidence for epigenetic variation

Abstract

The stalked barnacle Pollicipes pollicipes is an important economic resource in Portugal and Spain. Two extreme phenotypes can be identified, based on their morphology. More elongated barnacles are associated with bad quality and have a lower commercial value. The fishers perception about the existence, definition and causes for this phenotypical/quality variation was evaluated through a survey performed in Portugal and Galicia, Spain. The existence of two extreme commercial qualities was validated. Good quality barnacles were mainly defined as thick and short in both countries. In Spain (Galicia), the definition of bad quality animals corresponded mainly to the terms long and thin, while in Portugal, fishers used a wider variety of terms including watery, thin and soft. The characteristics of the rock and the hydrodynamics were the causes most referred by the fishers for this variation. The morphological variation of P. pollicipes was described by the ratio between maximal rostro-carinal length (RC) and total height (TH): RC/TH values ω 0.4 indicate good quality barnacles; and values ε 0.4 indicate bad quality barnacles. Although morphological variation between the two extreme qualities/phenotypes was found, no genetic (amplified fragment length polymorphism - AFLP) or epigenetic (methylation sensitive amplification poly- morphism - MSAP) differences were detected.