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Handsome guy, isn’t he? But were his ancestors capable of recolonizing from cryptic Northern refugial areas?
It’s all very well knowing all about the location of refugial areas and what happened to species whilst they were isolated in them, but I suppose none of this is really that relevant if those refugial populations had absolutely no impact on the flora and fauna of today. This is why my next post focuses on an article published by Sommer and Zachos (2009) who examine the hypothesised recolonisation of two temperate mammal species – the roe deer and the red deer – from refugial areas. Both species of deer once had relatively wide ranges which became drastically restricted when conditions turned unfavourable during the Last Glacial Maximum and the early Late Glacial period (Sommer and Zachos 2009). When the climate became warmer again, the deer were able to expand their ranges across Europe. In terms of their recolonisation, only the regions where the deer persisted during the LGM are relevant because this is the time at which their ranges were the smallest and their distributions most contracted.
Sommer and Zachos (2009) then go on to make some interesting points about the significance of cryptic Northern refugia. They state that the cryptic Northern refugia of red deer were impermanent because they were present during the ice age but disappeared at the time of the LGM, recolonizing only from more Southern refugia. They conclude from this that cryptic Northern refugia did not act as sources of recolonisation of temperate species, such as the deer. Only the regions where temperate species existed during the LGM are important in the recolonisation of higher latitudes. Although these cryptic refugia may be irrelevant in the case of these temperate deer species, they might not be in examples where temperature is not the limiting factor. Sommer and Zachos (2009) aren’t trying to completely undermine the importance of cryptic Northern refugia, they are just stating that when you are focusing on ‘LGM-driven distribution ranges and post-glacial recolonisation’ of temperate mammals, the term might be misleading. The authors suggest a clarification of terms is important when using the phrase ‘cryptic refugia’, highlighting precisely which phase of the Quaternary is being referred to.
This research has the potential to have a significant impact on understandings of glacial refugia and post-glacial colonisation of temperate species. The authors do state, however, that this can only be the case if their findings based on these two species can be generalised – would alternate conclusions may be reached if different species distributions were investigated?
