REPRODUCTIVE CHARACTERISTICS OF THE ALBINO MORPH OF THE CRAYFISH, PROCAMBARUS CLARKII (GIRARD, 1852) (DECAPODA, CAMBARIDAE)

The crayfish, Procambarus clarkii exhibits various body colorations, including an albino morph that lacks melanin and red pigments, except in the compound eyes. The albino phenotype segregates in a Mendelian way and is recessive to the wild-type (Nakatani, 1999). In the present study, we have examined the reproductive capacity of albino morphs of P. clarkii. Crosses between albino and wildtype individuals revealed that the number of juveniles produced from a couple of albino individuals was lower than that from a couple of wild-types. Both pleiotropy and inbreeding effects may be concerned in causing the lower fecundity in the albino form. When albino females mated with wildtype and albino males successively, both normal and white coloration appeared in the offspring of those crosses, indicating that both males had taken part in fertilization. This result is different from an earlier study on sperm competition in crayfish, in which paternity could invariably be attributed to the second male. The number of offspring from the multiple-mated females was higher than that of singly mated females. Thus, mating with multiple males may increase the effective fertility in albino females of P. clarkii.