Pollution selection of allozyme polymorphisms in barnacles

Allozymic variation in proteins encoded by 15 loci was analyzed electrophoretically in 166 individuals of the subtropical acorn barnacle Balanus amphitrite from 3 sites varying in pollution levels, situated within 3 km of one another in the Mediterranean Haifa Bay. The 3 sites respectively were a relatively unpolluted marine bay, a petroleum polluted port, and a petrochemically polluted dockyard. Out of the 15 loci tested, 10 exhibited in both 1974 and 1975 statistically significant repetitive trends in allele frequencies in accord with the 3 sites. It is hypothesized that natural selection presumably favours specific alleles in each site, and that in barnacles different allozymic variants function optimally in different polluted environment.