Boris is Back!

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So, we’ve established that, to be on the safe side, only refugial areas that existed during the LGM can be considered as the most important when thinking about recolonisation from cryptic Northern refugia. Seeing as there was a bit of controversy about using only pollen data in support of the cryptic Northern refugia hypothesis, I’ve found a study that is based on a different type of data but still focuses on LGM refugial areas.

 

Flojgaard et al (2009) used species distribution modelling to reveal the geographical distribution of suitable climatic conditions for particular rodent species during the LGM. The model predictions showed areas with suitable climatic conditions (i.e. possible refugial areas) for both the bank vole and the common vole as far North as Southern England during the LGM (see model map results in Figure 1). They also found areas of suitable climate for the tundra vole and the lemming across Central Europe and as far North as Russia. The model predictions for the boreal species are, therefore, in agreement with the cryptic Northern refugial hypothesis!

Source: Flojgaard et al (2009)

This study shows how species distribution modelling can complement palaeological and phylogeographical data sets and can help us gain further insight into and understanding of species distributions in the past and their possible responses to climatic change. Modelling of this sort offers a direct way of testing the mechanisms underlying past changes in species distributions or community composition – something which comes in very useful when gathering evidence in support of the cryptic Northern refugial hypothesis. I think it is vital that all lines of inquiry, whether it be investigating fossil remains, pollen analysis, DNA studies or computer modelling, be used to collect and present data in favour of the cryptic Northern refugia hypothesis. As we have seen so far, various methods have in fact been employed and a very convincing argument for the existence, importance and role of these more Northern refugial areas has been put forward.