Electrophoretic study on population structure of krill, Euphausia superba Dana, in the region of Drake Passage, Bransfield Strait and west of the Anterctic Peninaula

Abstract

Samples of Antarctic krill, Euphausia superba, collected from 18 locations in the Drake Passage, Bransfield Strait and on the west coast of the Antarctic Peninsula were analyzed for protein variation using enzyme electrophoresis. Of 19 enzyme loci studied, 14 (73,6%) exhibit allelic variations. Average heterozigosity for a station varies from 0,129 to 0,157. Five loci are with null alleles. Differences in allelic frequency related to sex and size of animal were not observed. No significant deviations from random mating expectation according to the Hardy-Weinberg principle were found in any locus at any station except Aph-1 at the stations 8 and 18; Est-1 at the station 9 and 11, and Mdh-1 at the station 18. These deviations are likely due to the difficulty in .analysing the enzyme pattern or to the small sample sizes. Analysis of allele distribution indicate that samples from all locations are homogeneous in all polymorphic loci. Genetic distances between samples vary from 0.000 to 0.002. These results suggest that specimens from all locations of the investigated region belong to a single genetically homogeneous population. The contribution of physical and biological factors to the homogeneity of krill in the region and the necessity of a detailed study utilizing not only electrophoresis but also another techniques were discussed.