MtDNA haplogroups and frequency patterns in Europe

Recently, an article by Simoni et al. (2000), who used (i) SAAP analysis to analyze the population frequencies of mtDNA haplogroups and (ii) AIDA analysis to examine both the frequency and the sequence similarity of truncated mtDNA sequences, appeared in this Journal. The main outcome of their study was that “the overall patterns of mtDNA diversity appear to be poorly significant in Europe.” Even when haplogroup assignment is done with care, failure to detect significant clines in haplogroup frequencies does not prove the absence of any spatial structure in the mtDNA pool. Such structure would rather be manifest at a phylogenetically finer scale (defined on the basis of more-recent mutations). In any case, one would not expect that meaningful patterns of mtDNA diversity could emerge from analyses based on categories with no demonstrable phylogenetic support.