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A high degree of polymorphism has been evidenced in Atherina boyeri . Several local populations have been distinguished in various studies, on the basis of morphological, morphometric, and biochemical parameters. The Rhone delta (the Camargue) exhibits a wide range of coastal brackish lagoons and freshwater marshes differing in their isolation, salinity, and distance from the sea. Some A. boyeri populations of these water bodies can migrate, particularly to spawn and may differ in their degree of differentiation and with regard to marine ones. We used electrophoresis to analyze small polymorphic muscle proteins, the parvalbumins (PA), whose isoform distribution is typical of a species and even of a population. We found a quite homogeneous ‘lagoon’ type distribution (presence of PA IV and III, lack of PA V typical of marine specimens) in populations from the Camargue. Three subgroups were distinguished in each population according to the percentage of PA IV/PA III. Two neighboring populations more connected to the sea were characterized by a greater preponderance of the PA IV isoform. |
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