The genetic structure of Drosophila subobscura populations from the islands of Majorca and Minorca (Balearic Islands, Spain) based on allozymes and mitochondrial DNA

The genetic structure of seven populations of Drosophila subobscura from di fferent locations on Majorca and Minorca (Balearic Islands, Spain) was stud ied using two types of markers: allozyme and mitochondrial DNA restriction analyses. Both markers showed congruent results. In the allozyme data, when the Acph-1 locus was excluded from the joint F-ST statistics, only three o ut of 21 comparisons were statistically significant, lending support to the hypothesis of low genetic differentiation. The mtDNA restriction analyses showed two haplotypes at a high frequency (more than 40% each), irrespectiv e of the location considered, and a number of endemic haplotypes at very lo w frequencies (not higher than 2% each). The analyses of the genetic struct ure yielded a pattern similar to the allozymes. The cytonuclear disequilibr ium analyses showed the difficulty of detecting cytonuclear associations in natural populations because they are mainly transient.