‘Super’ mouse evolves resistance to most poisons
Warfarin is a drug widely used in medicine as an anti-coagulant to prevent the build-up of harmful blood clots…Too much warfarin can cause fatal bleeding, and it was this quality that led to its introduction as a pesticide against rats and mice in the 1950s.
But the creatures have been slowly evolving traits to survive warfarin, and pockets of resistant rodents have been found in many different parts of the world.
Now scientists say that German and Spanish mice have found a rapid method of overcoming the threat by cross-breeding with Algerian mice that are, according to the researchers, an entirely different species.
“Most of the offspring… do not reproduce, they are sterile - but there is a small window, which remains open for genes to be moved from one species to the other, and that’s through a few fertile females - so there is a chance to leak genes from one species to another.”
Thanks to these few fertile females, the vast majority of mice in Spain and a growing number in Germany have acquired resistance over a very short period of time, although scientists aren’t exactly sure when the first genetic exchanges took place.
And while they may not look any different from normal household mice, in their genetic code they now have the ability to survive the strongest chemicals in the pest control armoury.
The researchers say that increased human travel and population growth are responsible for bringing these mice species together and putting them under evolutionary stress by trying to poison them.
They are concerned that similar human pressures could afford rats both the necessity and the opportunity to breed across species, resulting in rodents that are almost impossible to control.
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