Giving Biodiversity a Helping Hand

I’ve found a concise little paper that highlights the role that refugial areas play in the creation of genetic diversity and possibly even new species. I realise the study site isn’t the most Northerly of refugial areas but it illustrates my point quite well and I don’t see why the arguments put forward here can’t apply to more Northern refugia as well (although correct me if I’m wrong!).

Tzedakis et al (2002) present a high-resolution tree pollen record from a site in Greece to investigate the extent to which certain habitats remained immune from Quaternary climate variability (in other words acted as refugia) – see fig. 1 for the pollen diagram. Their results showed that temperate tree populations survived throughout this entire phase of variable climate, showing ‘muted oscillations’. They concluded that this data points to the existence of areas of ‘relative ecological stability’; a refugium with adequate moisture levels and suitable topography for the temperate tree species to survive. 

Source: Tzedakis et al (2002)

What’s the significance of these refugial areas?

During periods of glaciation the temperate species that were left isolated in refugia could have differentiated by selection and genetic drift. This ‘microallopatry’ (a mini version of allopatric speciation - click here for more information on mechanisms of allopatric speciation) would probably have been repeated every glacial period, with populations expanding their ranges in between. Each time the conditions became favourable again and the temperate species re-colonised from their refugia, each taxon would follow its own pathway of divergence and speciation. The pollen record presented in this paper allowed Tzedakis et al (2002) to see the climatic conditions that potentially could lead to ‘divergence and speciation, when populations remained effectively isolated over several glacial-interglacial cycles’.

This paper offers a quick introduction to the role that refugial areas play in generating genetic diversity and creating/shaping the diverse populations of flora and fauna we see today. It seems that the unique microclimates of refugial areas expose the temperate species to slightly different selection pressures to which they evolve in accordance with (if they are isolated long enough), as well as independently undergoing genetic drift and being subject to different genetic mutations. These refugial areas may be vital not only for the long-term survival of temperate species but also for the future development of new ones. Surely it follows that these areas should be identified as conservation priorities? Especially if they are unlikely to be as affected by future climatic change?


I was worried when I started this blog that the idea of cryptic Northern refugia, although interesting, is quite a niche topic - the only real source of information in this area is from academic literature and scientific journals (some of which are quite challenging to read!). I've been trying to blog about the topic in a way that makes it more easily accessible to people who don't necessarily know anything about it (as I didn't when I first started), so I think I'm really going to enjoy exploring the ways in which the ideas and arguments put forward in the cryptic Northern refugial hypothesis relate to more current and popular topics such as wildlife conservation and the issue of global warming. This article, as I've mentioned before, is an excellent 'foot in the door' to some of these issues and hopefully I will be able to find some more.