Differences between North American and European Populations of Balanus balanoides Revealed by Transplantation

Abstract

Transplants of specimens of Balanus balanoides from North Wales to Newfoundland, Canada, confirmed two innate differences between European and North American forms of the species. Breeding took place later in transplanted European populations. The eggs of the European form, though maturing later and therefore at a slightly lower temperature than the North American form, were distinctly smaller.The time of breeding both in the North American and European forms was earlier at higher latitudes, at higher shore levels, and in shelter.