Chromosome evolution in treehole breeding Anopheles (Diptera, Culicidae)

The cytogenetic profile of two Nearctic and one Paleartic treehole mosquitoes belonging to the Coelodiazesis group, Anopheles barberi, Anopheles judithae, and Anopheles plumbeus, was outlined by means of standard banding techniques and in situ hybridization. Results indicate that, during the evolution of this species group, several rearrangements have occurred including inversions, translocations, and loss of heterochromatic material and rRNA genes copy number. The karyotype of A. barberi is markedly different from the other two species, in spite of morphological similarities with the other North American species, A. judithae. This latter species has retained part of a more ancestral karyotype still shared with the Paleartic A. plumbeus. Chromosomal repatterning in A. barberi has probably facilitated isolation and divergence of the two Nearctic species, impairing introgressive hybridization with A. judithae.