‘Evolved’ mice defeats common poison

Mice have found ways of outwitting humans in the matter of survival - by evolving resistance to common poison.

New research by Michael Kohn and colleagues at Rice University analyses a genetic mutation that has given the ordinary house mouse this extraordinary ability.

A mutation to vkorc1, a gene present in all mammals, which manages Vitamin K, makes mice resistant to warfarin, an anti—coagulant used as a blood thinner in people as well as in rodent poison, the journal Current Biology reports.

Kohn, associate professor of ecology and evolutionary biology at Rice, said the mice evolved to become poison—resistant following two distinct processes, according to the university’s statement.

In point mutation, for instance, genes adapt through spontaneous mutations during DNA replication. Algerian mice, a desert—dwelling, seed—eating species, probably acquired the mutation this way to counter a Vitamin K—deficient diet, Kohn said.

Because rodents reproduce so quickly, their adaptation to warfarin is one of the few that can be observed directly during the lifetimes of evolutionary geneticists.

The poisons were introduced in the early 1950s, and poison—resistant rodents began to appear a decade later.

The other process, horizontal gene transfer, is generally associated with microbes, not mammals, and has never been documented at the level of detail the new paper offers, Kohn said.

Here, resistance seems to have been transferred directly from Algerian mice to European house mice. “A key element of this study is that we’ve caught evolution in the act,” he said.

A rodent pest—control specialist treating the basement of a German bakery found the first evidence that house mice had developed resistance to warfarin.