Whales are amazing creatures and are about 55 million years old. There are 84 living species and more than 400 other species that have gone extinct. They represent the most successful invasion of oceans by a mammalian lineage. The largest animal known to have ever existed is the blue whale, which is more than 100 feet long. By contrast the smallest whale is about the size of a dog.
The amazing diversity of whales has always fascinated the scientists. UCLA biologists decided to have a closer look at this phenomenon. They used molecular and computational techniques to go back 35 million years, when the ancestor of all living whales appeared.
The scientists found that very early in their history, whales went their separate ways in terms of size, and ecology. Species diversification and variations in body size were established very early in the evolution of whales. The shape of variation that we see in modern whales is the result of partitioning of body sizes early on in their history. The differences today were apparent very early on.
The rate of body-size evolution in the killer whale is the fastest. They become larger over the last 10 million years. Killer whales eat mammals, including other whales.
The analytical tools for integrating the fossil data with the molecular data are just being developed and exciting things are in store for the future.
Full details appear in the latest issue of journal Proceedings of the Royal Society B.
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