AB 11:149-155 (2010)  -  DOI: https://doi.org/10.3354/ab00301

Shell morphology changes in the scallop Aequipecten tehuelchus during its life span: a geometric morphometric approach

Federico Márquez1,2,3,*, Ricardo Amoroso1,2, María Florencia Gowland Sainz2, Silvina Van der Molen

1Centro Nacional Patagónico CENPAT – CONICET, Blvd. Brown 2915 (U9120ACD), Puerto Madryn, Argentina
2Universidad Nacional de la Patagonia San Juan Bosco, Blvd. Brown 3100, Puerto Madryn (U9120ACD), Chubut, Argentina
3Universidad Nacional de Córdoba, Av. Vélez Sarsfield 299, Córdoba (X5000JJC), Córdoba, Argentina

ABSTRACT: Shell morphology is a central feature of bivalve biology in fields such as taxonomy, evolution, and functional anatomy. When allometric shell growth occurs, traditional morphometric methods usually fail to provide robust, size-free shape variables. We used a more integrative approach, geometric morphometrics, to examine ontogenetic changes in the shell of the scallop Aequipecten tehuelchus. A single cohort that settled early in 2004 at a site in San José Gulf in northern Patagonia, Argentina, was sampled at irregular intervals over 5 yr. Different developmental stages had significant differences in shell shape. There was significant ontogenetic allometry, mainly reflected in the shape of the shell disc and the symmetry of the auricles. The most noticeable morphological changes in shell shape and size took place within the first 2 yr of life. Three different shell ecophenotypes were discriminated: spat, juveniles, and adults. Spat had a relatively large anterior auricle and a circular disc; auricles in juveniles were more symmetrical and the shell disc more elongated; and during the adult stage the auricles were small and asymmetrical and the disc elliptical. These 3 phenotypes may reflect changes in the scallop’s life habits, as individuals develop from attached spat to actively swimming juveniles to more sedentary adults.

KEY WORDS: Allometry · Geometric morphometrics · Ontogeny · Shell-shape · Tehuelche scallop

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Cite this article as: Márquez F, Amoroso R, Gowland Sainz MF, Van der Molen S (2010) Shell morphology changes in the scallop Aequipecten tehuelchus during its life span: a geometric morphometric approach. Aquat Biol 11:149-155. https://doi.org/10.3354/ab00301

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