ELECTROPHORETIC DATA SUPPORT THE LAST-MALE SPERM PRECEDENCE HYPOTHESIS IN THE SNOW CRAB, CHIONOECETES-OPILIO (BRACHYURA, MAJIDAE)

Controlled mating experiments were carried out with the snow crab, Chi onoecetes opilio, over two female breeding cycles. In this species, el ectrophoretic patterns of the enzymes glucose-6-phosphate isomerase, p hosphoglucomutase, and malate dehydrogenase observed in the parents an d the progenies are inherited as simple Mendelian codominant character s. The genetic differences observed between the larvae from the first and second egg clutches of some females mated with males of different genotypes support the hypothesis that the last male to mate with a fem ale before she extrudes an egg clutch fertilizes a large proportion of the extruded eggs.