Southern, Northern, Glacial or Interglacial Refugia?!

I was starting to get a little bit confused with all the different types of refugial areas mentioned in these scientific papers, but I’ve found an excellent summary in the conclusion of Stewart et al (2010)’s article (for a link to this reference see previous post). They propose that refugial areas can either be classified as ‘glacial’ or ‘interglacial’:

• Glacial Southern refugia are found at low-latitudes and harbour temperate species during glacial periods
• Interglacial Northern (or polar) refugia are found at high-latitudes and harbour cold-adapted species during warmer interglacials
• Cryptic Northern refugia existed during glacial periods, allowing temperate species to survive at higher latitudes
• Cryptic Southern refugia exist during interglacials, allowing cold-adapted species to survive at lower-latitudes (e.g. in the Apls today)
  

Cryptic refugia tend to consist of much smaller areas than the glacial Southern and interglacial Northern refugia. As glacial periods are longer than interglacials, temperate species are generally in isolation for longer periods of time. Long term isolation of small populations of temperate species (i.e. those in cryptic Northern refugia) can lead to rapid population divergence which, in conjunction with new selection pressures, can lead to speciation (like in the case of the polar bears).

I hope you find this useful!