Likely pre-Suez occurrence of a Red Sea fish Aphanius dispar in the Mediterranean

THE construction of artificial waterways connecting different faunal provinces provides biologists with an opportunity to observe ecological, biogeographic and evolutionary changes. But recognition of change requires a thorough knowledge of conditions before construction. The opening of the Suez Canal in 1857 is a case in point. More than thirty species of Red Sea fishes have been recorded as colonising the Mediterranean since the opening of the canal¹, but because no reliable systematic ichthyological collections were made in the eastern Mediterranean before 1857, these new records must be judged with caution. We report here comparative electrophoretic evidence which suggests that the Red Sea cyprinodontid, Aphanius dispar, first reported along the Israeli coast in 1947 (ref. 2) and therefore considered a Suez migrant, has been a permanent Mediterranean resident for a long time.