DYNAMICS AND CONSEQUENCES OF HIERARCHY FORMATION IN THE ANT LEPTOTHORAX SP-A

In the Nearctic ant Leptothorax sp. A, aggressive interactions among w ingless intermorphic queens and primarily winged gynomorphic queens le ad to the formation of dominance hierarchies, in which the highest-ran king individual is the only egg-layer in a colony. Fighting occurs dur ing two periods of the annual cycle: in late summer, newly adopted you ng queens are integrated into the colony's hierarchy; after hibernatio n, fighting resumes and the high aggressiveness of alpha-queens may no w lead to the emigration of beta and other middle-ranking queens. The alpha-position appears to be very stable over successive fighting peri ods, though an estimate of nestmate relatedness by allozyme electropho resis (polyacrylamide gels and cellulose acetate plates) suggests that queen replacement occasionally occurs. The mean relatedness determine d for adult workers in a functionally monogynous population of Leptoth orax sp. A was 0.54 and their effective number of mothers therefore 1. 5. This is lower than expected and found for monogynous colonies. Domi nance rank is apparently not correlated with queen morph, weight, and size, but an influence of insemination, age, or previous reproductive experience is likely.