Monday, 11 February 2013

DNA Mystery

Fudge: European or Syrian?
Here at Dartmoor Zoo there are two bears named Hayley and Fudge. It was originally believed that both were European Brown Bears, however there are notable differences between the pair. The most obvious differences, which indicate that Fudge may not be a European Brown Bear are the length of her claws, her overall size and fur colour. As a consequence, despite her records showing otherwise, we have long thought that Fudge is in fact a Syrian Brown Bear.

So, we decided to turn to scientists at Plymouth University for a definitive answer.

We contacted several zoos around Europe to find a collection willing to send hair follicles from a true Syrian Bear to compare to our own. Heidelberg Zoo in Germany kindly sent a sample of hair from a Syrian Brown Bear in their collection. We also took samples from our own bears, a process which thanks to their training was stress free for all concerned.

Dr Mairi Knight of Plymouth University’s School of Biomedical and Biological Sciences is currently working with the samples. At this point, it’s important to point out to all readers familiar with CSI that DNA sampling isn’t a straightforward case of shaking liquids about in test tubes.

The first step is to extract DNA from all the samples. Whilst extracting DNA from hair is now routine in many laboratories, since there is not much DNA contained in hair (the main source being from the follicle cells in the root) yields of usable material can be very small. To get at the DNA the scientist will digest the cells using particular enzymes to free up the DNA, and then carefully remove the other cellular material by a process of ‘chemical washing’ to leave a clean solution of just DNA. In mammal hair often colour pigments can inhibit part of the later processing and so care needs to be taken to ensure that these are also removed.

Once the DNA material has been isolated, a technique called ‘PCR’ (Polymerase Chain Reaction) is then used to amplify a small section of DNA into enough copies for analysis.

This final step involves using a Genetic Analyser which highlights the particular strands of interest. DNA sections or ‘regions’ that are known to be particularly useful for tracing the ancestry of a species will then be screened. The exact sequence of DNA from Fudge and the comparison brown bear samples can then be analysed for similarities and differences, allowing Fudge’s most likely ancestry to be determined.

There are many subspecies of the Brown Bear, which have adapted to different habitats making the specie as a whole more diverse. Brown Bears are distinguished from others by their shoulder hump, the consequence muscles specially adapted for digging. They have the widest distribution of any of the bears and can be found in Europe, Japan, North Asia and other places. Subspecies of the Brown Bear include the Alaskan, Asiatic and European Brown Bear, as well as the Grizzly Bear, Himalayan Snow Bear, Kodiak Bear and the Syrian Bear.

European Brown Bears have small, round ears and have brown fur ranging from yellow to dark brown. They can be found in Northern Europe and Russia and are the most widely distributed subspecies of bear.

Syrian Bears are the smallest subspecies of Brown Bear and the only Bear known to have long white claws. Their fur is very light brown while the fur on the shoulders has a darker grey base. Also, on some Bears there is a dark stripe running down the back.

Syrian Bears are found generally in the mountainous areas in Iran, Iraq, Turkey and the former Soviet Union, however due to habitat loss and poaching, the population is in decline. They can no longer be found in Syria.

Fudge is a very special part of the DZP collection. If our suspicions are confirmed, she will be the oldest of her kind in captivity (she recently celebrated her 35th birthday). However, the search for a definitive answer to the question of Fudge’s origins is a lengthy and complex process and there’s even the possibility that the results will raise more questions. There are some within the scientific community that believe, despite the obvious physical differences between what we term to be European and Syrian Brown Bears, that at a genetic level there is a case for declaring no difference at all.

We’re very much looking forward to seeing where our investigations will take us.

Hollie Dutton

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