Hybrids aren’t just funny looking cars…

Have you seen the film ‘Blade’ with Wesley Snipes?

Wesley has all the strengths of a vampire whilst keeping the ability to be a ‘day-walker’ and isn’t killed by sunlight. So he has all the positive vampire traits and doesn’t have any of the weaknesses (apart from a hunger for human blood which he counteracts with a specially devised serum that he injects) …so he is a hybrid…that thrives to the determent of all of his enemies.

Hybridization is the fundamental mechanism by which rapid evolution can occur in invasive species. If a hybrid shows increased vigour this would significantly contribute to invasion success.

CABI (www.cabi.org) have carried out a comparison of Fallopia japonica and Fallopia sachalinensis and the hybrid Fallopia x bohemica in competing against experimental communities of native plants. It was found that the knotweed hybrids performed significantly better in competition with a native community and that they strongly reduced the growth of native plants.

Of the parental species F. sachalinensis regenerated significantly from rhizomes suggesting allelopathic* inhibition by native plants.

The study found great variation between the various taxa but the hybrid proved to have the greatest success – thus proving that invasive knotweed hybrids are indeed more competitive than their parents.

We already know that Japanese knotweed has no natural enemies in the UK – (apart of course from the Psyllid aphid released by CABI as part of the Government bio-control strategy) – so with a mutational hybrid being even more efficient at spreading than the all-ready prolific plants that we struggle to manage – we could be in an even worse position…
Mike C

With thanks to CABI
NB: *allelopathy is the secretion of chemicals by plants to inhibit growth of other species