interbreeding

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.

Based on certain genetic similarities between the two species, researchers had an inkling that H. elevatus might have obtained some of its genes via interbreeding between its H. pardalinus ancestors and H. melpomene.

Continued interbreeding between hatchery-origin and natural-origin salmon could contribute to a decline in overall fitness for the natural-origin fish, unless the level of interbreeding is carefully managed, she said.

They also can weaken wild Chinook fitness by interbreeding or disease, noted study author Misty MacDuffee, salmon biologist with the Raincoast Conservation Foundation, a science nonprofit.