Allozyme differences between tidal levels in Tetraclita squamosa Pilsbry from the Red Sea

Intraspecific morphological differences related to the vertical position of Tetraclita squamosa Pilsbry from Elat on the intertidal zone have been previously reported. Using starch-gel electrophoresis, we have found differences in allozyme frequencies in animals from various tidal levels. We suggest that selection operates on certain morphological features which are correlated to different allozyme frequencies. Thus there are genetic variations in populations of barnacles which are at a vertical distance of only 50 cm apart.