Cats Climb New Family Tree

Maryann Mott
for National Geographic News
January 11, 2006

Researchers say they have solved an 11-million-year-old puzzle: how a single feline-like ancestor in Asia spread throughout the world and developed into all modern cat species.

Cats are native to all continents except Australia and Antarctica, and the 37 wild and domestic species living today belong to one of the world's most successful carnivore families.

The details of this evolution success story proved elusive for biologists, however, in part because of incomplete fossil records and the few distinguishing dental and skeletal characteristics among ancient cats.

But after nearly ten years of genetic research, a team led by Stephen O'Brien and Warren Johnson of the National Cancer Institute in Frederick, Maryland, has constructed a feline family tree that better charts the journey of cat evolution.

Analyzing genetic material from all living cat species, scientists read traces of the Felidae family history, such as divergences and booms and busts in populations, by the patterns of gene organization and diversity within and between species.

The scientists found that when sea levels fell, exposing land bridges between continents ten to three million years ago, ancient felines moved around the globe to areas where they had less competition.

Cats ended up in their current homes through at least ten of these intercontinental migrations.

During this time, felines did more than just roam. They also developed into new species when sea levels rose to cover land bridges and cut off cat species from their original groups.

"When you have two groups of populations that become isolated, they begin to drift apart," Johnson said. "They adapt to different things to the point where—when they have the chance of coming back together—they no longer can breed and, at that point, are distinct species."

This process happened rapidly and occurred numerous times over the past 11 million years, he said.

The radiation of modern felines began with the divergence of the Panthera lineage. From this common ancestor all the big cats emerged 6.4 million years ago—lions, jaguars, leopards, tigers, and snow and clouded leopards.

They were quickly followed by three Asian species (bay cat, marbled cat, and Asian golden cat) and three African species (caracal, serval, and African golden cat).

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