Shell-shape variation along the latitudinal range of the Chilean blue mussel Mytilus chilensis (Hupe 1854)

Abstract

Shell-shape variation in the Chilean blue mussel Mytilus chilensis was examined in eight populations covering the totality of its distribution range, which represents over 1800 km of latitudinal gradient in the southeastern Paci¢c. The shell outline shapes were assessed using elliptic Fourier analysis followed by canonical variates analysis. Fourier coe⁄cients showed a highly signi¢cant morphological variation between the populations studied. Canonical variates analysis showed a visual association of the First canonical with convexity of ventral edge and umbo shape, while the second axis was associated with shell elongation. Previously described genetic patterns were marginally congruent with our morphometric pattern, though geographic distance had a stronger e¡ect on morphology. Shape change (elongation) was correlated with latitudinal clinal variation. The morphometrical analysis proved to be an important tool for evaluating the components of shell-shape variation in mussels and to document association patterns with geographical and ecological variables. Such patterns are useful to establish awide ¢eld of work, including sexing, stock recognition, traceability studies and productive management in general.FONDECYT-Chile through project 1050848

Evaluacion del potencial reproductivo del chorito (Mytilus chilensis) de dos poblaciones naturales sometidas a diferentes temperaturas de acondicionamiento

“…Por otro parte, este índice puede presentar problemas cuando se comparan especimenes de diferente procedencia, puesto que se pueden encontrar diferencias en sus características como es el caso de M. chilensis, que presenta un mayor longitud relativa en la población de Zenteno (Krapivka et al, 2007). Este problema se solucionó comparando el incremento del IC contra los mismos ejemplares iniciales, en cada población y temperatura, evitando así problemas derivados de la distinta procedencia de los grupos estudiados al momento del análisis.…”

“…El recurso se extiende en la costa chilena desde Arica hasta Tierra del Fuego (Osorio, 1979;Lancellotti & Vásquez, 2000). Ocupa sustratos duros desde el intermareal hasta 25 m de profundidad (Rojas, 2003;Krapivka et al, 2007). Posee sexos separados (Rojas, 2003), con un ciclo reproductivo anual y desoves en primavera y verano (Toro et al, 2004a), con máximo desove en noviembre y diciembre.…”

Use of different geometric morphometrics tools for the discrimination of phenotypic stocks of the striped clam Ameghinomya antiqua (Veneridae) in north Patagonia, Argentina

“…Moreover, significant advances in morphometric analysis have occurred in the last two decades, offering more efficient and powerful techniques, such as image analysis (Cadrin and Friedland, 1999) and geometric morphometrics methods (Rohlf and Marcus, 1993) for detecting differences among groups. For example, some studies use mollusks' shell shape to differentiate between species of similar shape (Ferson et al, 1985;Innes and Bates, 1999;Dommergues et al, 2003;Aguirre et al, 2006;Rufino et al, 2006;Costa et al, 2008a,b) or to analyse intra-specific variation along a wide geographical range (Palmer et al, 2004;Krapivka et al, 2007).…”

Shell ecophenotype in the blue mussel (Mytilus edulis) determines the spatial pattern in foraging behaviour of an oystercatcher (Haematopus ostralegus) population

“…Durell and Goss-Custard 1984;Sutherland and Ens 1987;Nagarajan et al 2002a). Besides exhibiting diVerences in these shell features, M. edulis is also extremely variable with respect to the sagittal and lateral shape of its shell (Mitton and Koehn 1985;Innes and Bates 1999;Buschbaum and Saier 2001;Krapivka et al 2007). Certain shell shapes may, for example, be better at resisting the forces applied by hammering oystercatchers and thus may aVect the vulnerability of mussels to the diVerent foraging techniques.…”