Inversion polymorphism in a natural population ofAnopheles cruzii

SUMMARYA survey of a natural population of Anopheles cruzii from Aldeia dos Indios, São Paulo, Brazil, has disclosed the existence of a highly polymorphic genetic system characterized by the presence of 14 independent paracentric inversions and at least other five inversions belonging to two complexes. Most of the inversions have heterozygous frequencies higher than 25%. The mean number of inversions per individual was estimated as 5.9. Besides the two complexes, where the inversions were completely linked, four intrachromosomal and six interchromosomal nonrandom inversion associations were observed. In six of these nonrandom associations the 3Rd inversion was present. The presence of a highly polymorphic inversion system in this population is discussed, taking into account the variety of habitats explored by this species.