Extra Mediterranean Refugia of Cold Adapted and Temperate Species

During glacial periods, the regions between the Alps, Pyrenees, and Balkan mountains in the South and the Northern European ice shield in the North were largely covered by tundra and cold steppe on permafrost. Only cold-adapted species were

Fig. 1 The five major Mediterranean refugia and differentiation centers of the South European peninsulas (R1: Atlantic-Mediterranean in the Maghreb, R2: Atlantic-Mediterranean in Iberia, R3: Adriatic-Mediterranean, R4: Pontic-Mediterranean at the Balkans, R5: Pontic-Mediterranean in Asia Minor) and secondary contact- and hybridization zones during the postglacial range expansion (H1: Pyrenees, H2: Alps, H3 Western Central Europe, H4 Eastern Central Europe, H5: central Scandianvia). After Schmitt (2007), modified

Fig. 1 The five major Mediterranean refugia and differentiation centers of the South European peninsulas (R1: Atlantic-Mediterranean in the Maghreb, R2: Atlantic-Mediterranean in Iberia, R3: Adriatic-Mediterranean, R4: Pontic-Mediterranean at the Balkans, R5: Pontic-Mediterranean in Asia Minor) and secondary contact- and hybridization zones during the postglacial range expansion (H1: Pyrenees, H2: Alps, H3 Western Central Europe, H4 Eastern Central Europe, H5: central Scandianvia). After Schmitt (2007), modified able to survive under these extreme conditions. Many of these species are now restricted to the high mountain systems and/or the high latitudes of Eurasia, though they sometimes even reached North America (Holdhaus and Lindroth 1939; Holdhaus 1954; Varga and Schmitt 2008). Some, however, also have relict populations in cold habitats of lower mountain ranges. Stony debris formations with their exceptionally cold microclimatic conditions (at some sites with permafrost ground) host such species (Molenda 1996). Some of these species live exclusively North of the Alps (and not in the Alps!), thus making them Central European endemics (e.g., the ground beetle Pterostichus neglectus). However, many typical mountain species also showed discontinuous distribution patterns around the predominantly glaciated high mountain systems during the ice ages.

Furthermore, growing evidence supports the survival of numerous species which require woodlands or temperate climatic conditions North of the Mediterranean refugia scattered over large areas of Central Europe (Englbrecht et al. 2000; Jaarola and Searle 2002; Babik et al. 2004; Fink et al. 2004; Pinceel et al. 2005). This mainly coincides with the detection of woodland or at least tree species refugia in Central Europe during glacial periods (e.g., Willis and van Andel 2004). The Black Forest (and/or an area in its vicinity), for example, is discussed by Fink et al. (2004) and Drees et al. (2009) as a possible glacial refugium for woodland dwelling species.

Phylogeographic studies on some vertebrates supported the existence of previously unknown, or cryptic, refugia (e.g., in the Carpathians). The genetic differentiation of seaweeds, coupled with the concordance of similar patterns across these species, gives reason to conclude that some marine species persisted through the last ice age in flooded depressions on the floor of the present-day English Channel (see Provan and Bennett 2008 for a review of these cryptic refugia). Using an integrative approach with both fossil and genetic data, Petit et al. (2008) concluded that some temperate and boreal trees apparently survived the last glacial maximum under periglacial conditions, probably close to ice sheets and even in unglaciated areas North of ice sheets. All these recent results are beginning to revolutionize our understanding of glacial refugia for cold-adapted and temperate species. Analyzing the species distribution models with moderate to good predictive ability, Svenning et al. (2008) concluded that the view of Central European landscape North of the Alps as largely treeless needs to be revised.

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