Resumen del producto

The genus Spondylus has played an important economic, political and cultural role in human communities along the Eastern Pacific, with S. calcifer particularly valued as food. Spondylus calcifer is distributed from the coast of Peru to Mexican waters, including both coasts of the Gulf of California. Actually its population size has been so reduced that it has been placed in the category of special protection under legal standard NOM-059. For this reason, efforts focused on understanding the population dynamics of this species are relevant to support its management. We used geometric morphometrics to quantify the differences in body shape which can occur as a result of biological processes such as disease, ontogenetic development, ad­aptation to local geographical factors, or differences due to evolutionary processes. Also, the application of this technique has allowed us to review graphically the variations that occurred between species and populations. To infer the existence of distinct populations or stocks in this region, we estimated the level of morphological differentiation of individuals from two sites in the Gulf of California. Forty-two individuals of S. calcifer were collected in Agua Verde and 47 in Bahía de los Ángeles, both sites located on the west coast of the Gulf of California. Photographs were obtained of the left valve (inside) of each organism. Thirty-two landmarks were digitalized to obtain coordinates used as variables for multivariate analysis. Prior to statis­tical analysis, the coordinates were standardized to eliminate the effect of scale, position and rotation by using the method of generalized Procrustes superimposition. The results of multivariate analysis of variance (MANOVA) indicated significant differences between the two sites (Wilks› lamba = 0.1342 P <0.001). The morphometric distance also supported this result (F-Procrustes = 4.03, P <0,005). This morphometric results suggests the existence of distinct groups, which may represent genetically distinct populations or phenotypic stocks as a result of environmental differences along the Gulf of California. Future analysis using molecular markers will allow a better understanding of the processes of population dynamics of this species.

Palabras clave:

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx