Competition Experiments Between Parthenogenetic and Sexual Strains of the Brine Shrimp, Artemia Salina

Parthenogenetic and dioecious strains of the brine shrimp, Artemia salina, were allowed to compete under high and low feeding regimes and with variable strain combinations. Under high feeding and high density conditions, extinction of the apomictic strains occurred in all five trials, but under low feeding rates and low density neither reproductive mode was significantly superior; unisexual strains were eliminated in six of eight trials, but out—competed sexual strains in the remaining two. Dioecious strain extinction under the low feeding and low density conditions is possibly attributed to a shortage of ♂♂, resulting from either higher ♂ than ♀ mortality or through the capture of ♂♂ by parthenogenetic ♀♀