COMPARISONS OF GENETIC-VARIABILITY AND GENOME STRUCTURE AMONG MOSQUITO STRAINS SELECTED FOR REFRACTORINESS TO A MALARIA PARASITE

Restriction fragment length polymorphism (RFLP) markers were used to e valuate Aedes aegypti genome structure and genetic variability within and between substrains selected for different levers of refractoriness to the malaria parasite, Plasmodium gallinaceum, The MOYO-R substrain was previously selected for complete refractoriness and the MOYO-IS s ubstrain for intermediate susceptibility from the Moyo-In-Dry (MOYO) s train by selective inbreeding (F = 0.5), Eighteen mapped RFLP markers were used to provide coverage of the mosquito genome, The two substrai ns showed reduced genetic diversity compared with the MOYO strain, inc luding significant reductions in mean heterozygosity, number of allele s per locus, and proportion of polymorphic loci, Genetic differentiati on between the two substrains was statistically significant, as reflec ted by differences in allele frequencies, Significant pairwise linkage disequilibrium among the RFLP loci was detected in all three strains, most evidently in the MOYO strain, This is surprising because the RFL P loci examined are separated by large map distances, and therefore li nkage disequilibrium should decay to zero after many generations of la boratory culture, Our hypothesis to explain this phenomena is that lac k of recombination, or low recombination rates in some regions of the A. aegypti genome, is a result of chromosome inversions, Finally, we u sed graphical genotyping, wherein whole genome genotypic information f or individual mosquitoes is represented in a simple graphic format, to illustrate genome structure and allelic variation within and among th e mosquito strains, Our analysis revealed an apparent chromosomal dele tion on chromosome 3 for some individuals in the MOYO strain and MOYO- IS substrain.