Microsatellite DNA polymorphism and heterozygosity among field and laboratory populations of Anopheles gambiae s.s. (Diptera : Culicidae)

We compared microsatellite polymorphism at nine loci located on chromosome 3 among two colonies and a field population of Anopheles gambiae sensu stri cto Giles mosquitoes. Numbers of microsatellite alleles observed at each lo cus and mean heterozygosities were drastically reduced among laboratory col onies. Genetic analysis of the field population used in this study revealed an unprecedented frequency of rare alleles (<0.05). In contrast, colony sa mples revealed large numbers of alleles with frequencies >0.50. Partitionin g of field data to assess the impact of rare alleles, null alleles, and sam ple size on estimates of mean heterozygosity revealed the plasticity of thi s measurement and suggests that heterozygosity may be reliably estimated fr om relatively small collections using microsatellites.