Welcome to the Saturday edition of The Conversation U.S.’s Daily newsletter.

One lesson I remember learning in biology class was about how animals from one species can’t breed with animals from another species. In fact, my understanding was that part of how you defined a species was whether the animals could all interbreed.

Well, hold on to your hat if that was your bio-class takeaway, too, because as Penn State evolutionary biologist David Toews writes, “In reality, biology always has its exceptions and fuzzy edges.” His research focuses on one of those blurry zones: interbreeding between wood warbler species that reside on neighboring twigs of the evolutionary tree.

If any hybrid offspring result when these colorful songbirds interbreed, things can get interesting from an evolutionary perspective. These hybrids can bring useful new genes to a different population – creating a tricky shortcut for solving evolutionary challenges. Toews describes one example involving insect diets, colorful pigments and female songbirds’ mate preferences.

This week we also liked articles about fake political videos, the Trump administration’s AI executive order, and how PFAS can complicate pregnancy when they contaminate drinking water.

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