Whale evolution

Just how fast was the early evolution of whales? The diversity of the group is fairly remarkable - almost 100 existing species of a wide range of sizes and filling a range of niches. A great many fossil species that have come and gone. All living forms are descended from a common ancestor that lived relatively recently, about 35 million years ago. The perception is that whales must have hit on a big new idea, evolutionarily speaking, that triggered an evolutionary explosion. Is that actually the case? A new paper coming out of UCLA and appearing online at Proceedings of the Royal Society B explores this question.

Employing a variety of computational and molecular techniques, the researchers demonstrate that whales, early in their evolution, had begun to diverge along different lines. This is clear from an examination of the size and trophic habits of early whales. Early on, small whales feeding on fish, moderately-sized whales feeding on squid, and large, plankton-feeding whales were already present 25 million years ago, and that triumvirate of whale niches exists largely unchanged today. There are exceptions, of course, Killer whales, somewhat unique in their preference for feeding on other mammals, have only evolved their large size within the last 10 million years or so.