BIODIVERSITY AT THE INTRASPECIFIC LEVEL - THE COMPARATIVE PHYLOGEOGRAPHIC APPROACH

Biodiversity, or biological diversity encompasses species richness as well as intraspecific genetic variation. The knowledge of intraspecifi c variation is of prime importance for biotechnologists who want to us e a wild species as a genetic resource. A total of eight comparative p hylogeographic studies available at the moment are reviewed in order t o deduce general rules governing the geographic distribution of intras pecific biodiversity. Three studies are continent-wide surveys, in Nor th America or in Europe, while the others deal with more restricted ar eas. Although the overall information is still scarce, two interesting trends have been deduced. First, the level of intraspecific polymorph ism seems to be lower at higher latitude, particularly in areas glacia ted during Pleistocene cold periods, and most of the variation lies in areas that corresponded to refugia during range contractions. Second, the evidence for concordance of phylogeographic patterns among taxa a re controversial; all the studies concerning a limited geographic area suggest a certain level of concordance, whereas the continent-wide su rveys argue more for nonconcordant patterns. In order to survey as muc h as possible of the intraspecific genetic variation, I suggest sampli ng in widespread localities, and to pay special attention to areas tha t are thought to be refugia during cold periods. (C) 1998 Elsevier Sci ence B.V. All rights reserved.