Types of oreal and oreotundral disjunctions in the western Palearctic

The cyclic changes of the Pleistocene between cold and warm periods resulted in antagonistic responses within two different groups of organisms: one expanding during the warm periods and retracting during the cold phases and another with opposed responses. The latter group is composed of so‐called arctic and alpine species. These species have recently become the focus of phylogeographical research. However, we still lack a comprehensive characterization of the different types of alpine and arctic‐alpine disjunctions in the western Palearctic. Such an overview might facilitate the selection of different model species to test the different patterns of disjunctions for congruences revealing their past distribution. Therefore, we list all alpine and arctic‐alpine disjunction types of the western Palearctic using butterflies and moths as a model group. We distinguish between (1) endemics of the Alps (α) with strongly restricted and (β) with broader distributions; (2) alpine disjunct species (α) with perialpine disjunctions and (β) with a wide western Palearctic distribution; (3) oro‐Mediterranean species; and (4) arctic‐alpine disjunct species. These types of distributions and further subtypes are exemplified using chorological data of butterfly and moth species. In this context, we discuss the intraspecific differentiation and the differentiation among sibling‐species within and among disjunct parts of the distribution area. We also formulate hypotheses of the distribution patterns during the last ice age which might best explain the actual patterns. Finally, we suggest some case studies of genetic analyses to test the above mentioned hypotheses. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 415–430.