interbreeding

Scotland's nature agency NatureScot refers to these animals as feral pigs, and said they include hybrids - a mix of boar and domestic pigs following interbreeding.

"Are they co-operative, is there interbreeding, are the locals able to make their way into the elite?"

Even after our successful interbreeding with Neanderthals, our population of Europe wasn't without hitches.

Duplicated and rearranged genes can account for some of this knottiness, Renner explains, as can interbreeding among these diverging plants.

But whether that interbreeding was critical to H. elevatus separating from H. pardalinus and becoming its own distinct species was a mystery.