Abstract

BRIONES, CAROLINA  and  GUINEZ, RICARDO. Bilateral asymmetry of shell shape and spatial position in matrices of the mussel Perumytilus purpuratus (Lamarck, 1819) (Bivalvia: Mytilidae). Rev. chil. hist. nat. [online]. 2005, vol.78, n.1, pp.3-14. ISSN 0716-078X.  http://dx.doi.org/10.4067/S0716-078X2005000100001.

In the literature, less attention has been paid to the study of directional asymmetry (DA) than fluctuating asymmetry (FA). Although there are good examples of DA in mollusks (e.g., Ostreidae and Pectinidae), for some taxa, such as mussels, DA has not been reported. We examined asymmetry in two shell shape traits of the mussel Perumytilus purpuratus, in the rocky intertidal zone of three localities in central and northern Chile. We compared shell asymmetry between mussels occupying different positions in the matrices or mussel beds (i.e., upper versus lower stratum). We observed shell shape DA for mussels occupying both strata, with the right valve being consistently less elongated than the left valve. However, for individuals in the lower strata the mussel valves tended to be more elongated, and also more asymmetrical, relative to mussels from the upper layer of the matrix. These results suggest that changes in the shape and asymmetry of the mussel valves may be modified by density and stratification in the beds. The causal explanations of this phenomenon are open to further research

Keywords : directional asymmetry; fluctuating asymmetry; mussel; mytilid; shell shape.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )