This BBC News story, “‘Super’ mouse evolves resistance to most poisons” by Matt McGrath, reports that mice resistant to most mouse poisons “evolved” the trait by interbreeding with a species of Algerian mice from whom they have been separated for 1.5 to 3 million years. In other words, they acquired the trait through hybridization. The details are interesting:
“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.”
“There are a lot of genetic barriers between these species of mice, to see them hybridise and transfer genetic material is quite spectacular, to be frank,” said Professor Kohn.
Human travel brought the two species together, it is suggested, and pest control put them under evolutionary pressure.
The study authors’ claim that this is horizontal gene transfer (HGT) is disputed because, as another gene researcher Julie Hotopp, points out, the concept of HGT is only meaningful in the absence of sex. She adds, “”In many respects I don’t think it’s surprising, anytime you have a strong pressure like a pesticide, you will have the opportunity to have these changes.”
Opportunity maybe. But it is a rare natural situation, given that extirpation (extinction in a given area) is so much more likely than finding a species distant in time and place with which there can be fertile hybrids.
So it’s not clear what the mouse example contributes to the study of the history of life prior to human globetrotting. But it surely points to an interesting future – in the Chinese sense.