Dear Readers, it’s very hard to actually see evolution in action, but some very good news from the research team at Kew Gardens, led by Richard Buggs(who should surely be an entomologist) suggests that ash trees are gradually acquiring resistance to the fungus that causes ash dieback.

Ash dieback prevents an ash tree from taking up water, and gradually kills it – initial estimates were that over 95 percent of all the ash trees in the UK could be destroyed by the disease. So, the findings of this study are most encouraging. The scientists compared the genomes of adult trees, who were around before ash dieback arrived, with the genomes of young trees that had emerged since. They had a list of 8,000 genetic variants, each of which was thought to have a micro-effect on increased resistance, and found that there were many more of these variants in the young trees than in the old ones: presumably trees who didn’t have these variants were more likely to die off.

Each variant only has a tiny effect on resistance, but it is very unusual to see such a suite of changes in one generation. Buggs suggests that ash trees might need a helping hand, with more resistant trees being bred together, or even outcrossed with other species of ash which have more resistance. But this really is very good news, considering the dire initial predictions. With the problems of climate change and invasive organisms acting as a double threat, we need all the hope we can get!

Ash tree in St Pancras and Islington Cemetery

You can read the abstract from the research paper here. The New Scientist article is here.