MALE COMPETITION IN CARDIOCONDYLA ANTS

The two types of males in the ant genus Cardiocondyla differ remarkabl y in morphology and behavior. Ergatoid males are wingless fighters who se spermatogenesis continues throughout their entire adult lives and w hich therefore have an ''unlimited'' sperm supply. They attempt to kil l all eclosing ergatoid rivals and thus to increase their share in cop ulations with the virgin queens reared in their nests. Winged males, o n the other hand, are docile and emigrate from the nests a few days af ter eclosion, probably to mate with queens from other colonies. By thi s time, their testes have fully degenerated and all sperm is stored in the seminal vesicles. Before emigration, winged males may mate with v irgin queens in their maternal nests, but they are nevertheless rarely attacked by ergatoid males. In the laboratory, the life expectancy of ergatoid males is only slightly higher than that of winged males, but because of the emigration of the latter the difference is likely to b e more pronounced in the field. Both male morphs are capable of insemi nating more than 35 virgin queens. However, winged males older than 14 days mate less often than ergatoid males of similar age, probably due to sperm depletion in later life. The spermathecae of queens insemina ted by ergatoid males contained significantly more sperm than those of queens which mated with winged males. We discuss the evolution of int ranidal mating and male polymorphism in ants.