The black fur allele has fitness costs but also confers higher immunity against canine distemper virus, making mix-and-match mating key to population survival.
Bettas were likely the first fish welcomed into human homes. Now, scientists are welcoming them into the lab to learn how genes dictate their appearance and behavior.
This year’s most captivating illustrations tell stories from the micro scale—such as newborn neurons in the adult brain and bacteria in the infant gut—to the scale of entire ecosystems, including reintroduced predators and rising seas.
In some finch species, the difference between colorful males and muted females comes down to one gene, BCO2, which encodes an enzyme that degrades carotenoids.