Glacial survival hypothesis

According to the northern cryptic glacial refugial hypothesis (or glacial survival hypothesis), during the last ice age cold tolerant plant and animal species (e.g. Norway spruce and Norwegian lemmings) persisted in ice-free microrefugia north of the Alps in Europe.

There is a long-standing debate on what happened to the species that were inhabiting high-latitude regions during the Pleistocene ice age.

[4][5][12][13] A number of recent studies indicate that several northern regions (above latitudes >45° N) supported low-density boreal and temperate tree populations during the late-glacial or Early Holocene [e.g. North America, Eurasia, Alps, Scandinavia].

[4][14][15][16][17] In recent years several studies have combined lines of evidence coming from three major disciplines to infer the existence of past refugia: fossil records, species distribution models and molecular/phylogeographic surveys.

There has also been research to suggest that certain cold-tolerant tree species were able to survive the low temperatures thanks to the presence of a co-dependent beetle by the name of G.