POPULATION GENETIC-STUDIES ON CRANGON-CRA NGON AND C-ALLMANNI (CRUSTACEA, DECAPODA) FROM EUROPEAN COASTAL AREAS

The population structure of the common shrimp Crangon crangon (L.) fro m the Northern and Western European coast was investigated for genetic variation by means of starch gel electrophoresis. Samples were collec ted from Germany (Baltic and North Sea), Netherlands, Ireland, France, Portugal, and Italy. Furthermore, C. crangon was compared to its cong ener C. allmanni KINAHAN from Helgoland and Scotland. - Most of the lo ci studied (18 gene-enzyme-systems including 23 loci) appeared to be m onomorphic, or slightly variable in only a few populations; therefore, genetic diversity was supposed to be quite low in both species (H ca 0.04). - By analysing the polymorphic loci Pgi (phosphoglucose isomera se), Pgm-1 (phosphoglucosemutase), and Mpi (mannose phosphate isomeras e), the local populations of C. crangon could be arranged in four regi onal groups: North Sea and Baltic, N-Atlantic, Portugal, and Adriatic, the latter being the most divergent of all. Genetic variability was n ot found to be related to salinity. - With respect to the three polymo rphic loci, C. crangon and C. allmanni seemed to be highly differentia ted (D = 4.99; I = 0.007); when all the loci studied are included in t he estimation of the degree of divergence, C. crangon and C. allmanni were separated by a genetic distance (D = 1.34; I = 0.262) which is ch aracteristic of the species level (congeneric).