Since Charles Darwin wrote "The Origin of Species" more than 150 years ago, it's been known that nature's selection creates some species and ends others.

But researchers at the University of Maryland, Baltimore County suggest that another actor is responsible for driving wedges in animal populations to create new species — mothers themselves.

A study published last month in the journal Ecology Letters suggests that female creatures' sexual preferences may launch an evolutionary process that can lead to the creation of new species. Whom they choose for mates trickles down through generations in such a way that, combined with other factors, may make a population distinct from others with which it once intermingled.

It's a theory that is gaining acceptance relative to the idea that adaptation to differing environments — Darwinian "natural selection" — is mainly, if not solely, what drives evolution of new species.