GENETIC-STRUCTURE OF THE COMMON SOLE SOLEA-VULGARIS AT DIFFERENT GEOGRAPHIC SCALES

The genetic structure of the flatfish Solea vulgaris was investigated on several spatial scales and at the temporal level through analysis o f electrophoretic variation at 8 to 12 polymorphic enzyme loci. No dif ferentiation was apparent at the temporal scale. Some differentiation was detected at and above the regional scale. Isolation by distance wa s evidenced by the significant correlation between genetic and geograp hic distances, and by the consistency of the results of multiple-locus correspondence analysis with geographic sampling patterns. The analys is suggested that the geographic unit of population structure (i.e. a geographical area corresponding to a panmictic or nearly panmictic pop ulation) lies within a radius of the order of 100 km. The isolation-by -distance pattern in S. vulgaris contrasted with the known genetic str uctures of other flatfish species of the northeastern Atlantic and Med iterranean in a way that may be related to the range of their respecti ve temperature tolerances for eggs and larvae.