Abstract:
Mark recapture and morph frequency data, gathered during a population irruption of Hypolimnas
misippus in southern Ghana, provide evidence for apostatic and mimetic selection. During a period
of low adult survival, both the recapture rate and the frequency of the commonest morph (misippus)
were significantly reduced. Selection against this form increased phenotypic diversity and generated
significant disequilibrium in the combinations of unlinked fore- and hindwing phenotypes. There
was also evidence for selection against those forms (weak akippoides) which most closely resemble
misippus. Other morphs, including both good mimics of Danaus chrysippus and rare non-mimics,
showed no reductions in recapture rate during the period of low survival, but only the good mimics
increased significantly in frequency. The results provide a predictive ecological model for densitydependent selection by predators which is consistent with field data from previous studies of
H. misippus in Ghana and Tanzania. Their evolutionary implications are discussed, and it is
suggested. that anomalies in the mimicry of this species may be partly due to lack of predation when
it is scarce.
