Genetic distance between two sibling species of the Aedes mariae complex (Diptera, Culicidae)
Cianchi, R.; Urbanelli, S.; Coluzzi, M.; Bullini, L.
Parassitologia 20(1-3): 39-46
1978
ISSN/ISBN: 0048-2951 PMID: 553279 Document Number: 136494
The sibling species Aedes mariae (Ed. & Et. Serg.) and A. zammitii (Theo.) are allopatric (one in western Mediterranean areas, the other on the Adriatic, Ionian and Aegean coasts) but show similar adaptations to rocky Mediterranean coasts. Isolation mechanisms between the 2 species were known to exist, since males of the F1 hybrid generation were partially sterile in laboratory crossing experiments, while in the field the frequency of hybrids never exceeded 2% without evidence of introgression. In the present studies, genetic variation was analysed in populations of each species at 26 enzyme loci of which 35% were polymorphic, with an observed mean heterozygosity of 0.07 in A. mariae and 0.06 in A. zammitii. The existence of highly variable and fast evolving loci (including variable substrate and regulatory enzymes) and of conservative and slowly evolving loci (including non-regulatory enzymes), and the values of genetic distance calculated separately for the 2 groups, indicated that the main contribution to genetic distance in the first period of divergence was made by the 'fast' loci, which evolved about 10 times as rapidly as the 'slow' loci.