English elm is a 2,000-year-old Roman clone

摘要

This tree's genetic uniformity may have helped to fell entire European populations. The outbreak of Dutch elm disease in the 1970s ravaged European elm populations, killing more than 25 million trees in Britain alone; the greatest impact was on Ulmusprocera, otherwise known as the English elm. Here we use molecular and historical information to show that this elm derives from a single clone that the Romans transported from Italy to the Iberian peninsula, and from there to Britain, for the purpose ofsupporting and training vines. Its highly efficient vegetative reproduction and its inability to set seeds have preserved this clone unaltered for 2,000 years as the core of the English elm population -- and the preponderance of this susceptible varietymay have favoured a rapid spread of the disease.