By Susan Milius
Mighty Mouse may have gotten a very important superpower — resistance to widespread rodent poisons — through some mistaken-identity sex.
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Since the rat poison warfarin and others in its class of rodenticides went into use in the middle of the last century, various populations of mice and rats have turned up with abilities to survive exposure, explains evolutionary biologist Michael Kohn of Rice University in Houston. He and a U.S.-German research group have now found that some of the house mice (Mus musculus domesticus) in Germany and Spain take their resistance from a key gene’s alternative version that came from a completely different species.
In the history of the house mice, at least one “desperate, lonely mouse,” as Kohn puts it, mated with an Algerian mouse (Mus spretus), a species whose range extends into Iberia and southern France. This interspecific pairing doesn’t produce a lot of reproductively successful offspring. Yet the strong evolutionary force of widespread poison drove borrowed resistance genetics from the Algerian mouse to spread among house mice, the researchers report in the August 9 Current Biology.