GENETIC VARIATION WITHIN AND BETWEEN GEOGRAPHICALLY SEPARATED POPULATIONS OF THE SEA URCHIN,ARBACIA PUNCTULATA

Abstract

Genotypic variation, inferred from isoenzyme differences in 12 enzyme systems, was measured by horizontal microacrylamide gel electrophoresis in 4 populations of the sea urchin, A. punctulata, from the Atlantic coast of the USA. An additional population from the Gulf of Mexico was surveyed for 4 enzymes. Although gene frequencies were significantly different among Atlantic populations, the overall values of genetic distance were within the range observed for geographic populations of other species. A balance between migration and selection is proposed to account for the patterns of genetic variation. Striking differences in gene frequency were not observed when Atlantic coast populations were compared with Gulf of Mexico specimens.