Phylogeography and postglacial colonization routes of Ips typographus L-(Coleoptera, Scolytidae)

Ips typographus populations were analysed by enzyme electrophoresis and by sequence analysis in order to quantify the degree of population differentia tion. Enzyme electrophoresis showed a high gene flow among all European pop ulations. Analysis of single loci showed that aspartate amino transferase-2 (Aat-2) clustered the Scandinavian populations apart from the other popula tions whereas other enzyme loci showed no significant pattern. Analysis of mitochondrial DNA revealed eight haplotypes. The populations from Italy, Cr oatia and Belgium were the most polymorphic. Two haplotypes (1 and II) were found in the majority of Central European populations. In the northern pop ulations only one haplotype (I) was found. The Russian and Lithuanian popul ations had a particular haplotype (IV) that was not found in any of the oth er populations. In view of these data it is suggested that the population s tructure of I. typographus has been influenced by events which took place d uring and after the last ice age. Populations were forced into refugial are as in the south and in the area north of Moscow along with the host tree, P icea abies. P. abies had four refugial areas: the Apennine Alps, the Dinari c Alps, the Carpathian Alps and Kostroma, an area north of Moscow With amel ioration of the temperature, beetles spread after P. abies. According to th e data presented here, I, typographus migrated from the Apennine and/or Din aric Alps to the north. Whilst there is evidence for high gene flow among p opulations, bottleneck effects can still be detected in the north and also in the east. Beetles from the refugial area north of Moscow did not spread to Scandinavia or to the west like the host tree.