https://phys.org/news/2018-10-scientists-california-academy-sciences-species.html

The team examined the well-photographed genus Hypselodoris, a group of sea slugs that encompasses all 17 of these new finds. Two decades ago, Gosliner and Academy scientist Dr. Rebecca Johnson considered species relationships within the group on the basis of anatomy, not color. Now equipped with cutting-edge genetic tools, the team reorganized the family tree for Hypseledoris taking both color and anatomy into account. In the process, they revealed how color patterns arise among—and even within—species.

"When we find an anomaly in color pattern, we know there's a reason for it," says lead author Hannah Epstein, former Academy volunteer and researcher at James Cook University in Australia. "It reveals a point in evolution where a selective pressure—like predation—favored a pattern for camouflage or mimicking another species that may be poisonous to would-be predators."