For many years, Grey Squirrels (an introduced North American species) has been driving out the indigenous Red Squirrel over most of mainland Britain. But now it is reported that a mutant black variety of the Grey Squirrel is threatening to displace the Greys. Apparently, the black ones have higher testosterone levels, are more aggressive, and more attractive to the lady squirrels. (Don't worry, our White Nationalist readers, this isn't a parable. I think.)

Joking apart, the real interest of this is that it seems to be a case of a single mutation with a relatively conspicuous phenotypic effect having a strong evolutionary advantage, somewhat contrary to Darwin/Fisher orthodoxy. There is of course another example in the case of industrial melanism.

Labels: Pigmentation