Rare Pink Iguana Evaded Darwin

Jan. 5, 2009 -- When English naturalist Charles Darwin explored the Galapagos Islands in the early 1800s, he, and countless scientists since, overlooked a hefty pink iguana.

The iguana, referred to as "rosada," meaning "pink" in Spanish, has black stripes and is believed to be extremely rare. It was discovered at Volcan Wolf, Isabela Island's northernmost volcano, which Darwin missed during his five-week stay at the archipelago in 1835.

Galapagos National Park rangers first stumbled upon the striking land lizard a few decades ago, but this week's study in the Proceedings of the National Academy of Sciences is the first to officially document the iguana.

"Although 1986 was the year of the first sighting, our work discloses to the world the existence of this new species for the first time," lead author Gabriele Gentile told Discovery News.

Related Content:

Gentile, a researcher in the Department of Biology at Tor Vergata University in Rome, and his colleagues took blood samples from several Galapagos iguanas, including the better-known yellow species. They extracted DNA from the blood to illuminate how the different species are related to each other and when each emerged.

The scientists discovered that the pink-and-black iguana has been around for a very long time.

Based on this study and earlier work, Gentile and his team believe that 10.5 million years ago, a common ancestor to both marine and land iguanas from Central or South America colonized the Galapagos Islands. The marine and land iguanas probably diverged at that time.

Most researchers have thought that all major iguana species differentiated much later during the Pleistocene Epoch (1.8 million to 10,000 years ago). That wasn't so, according to Gentile and his team.

"The pink iguana alters the current thinking about the origin of land iguanas from the Galapagos," he said. "It is the only remnant of an evolutionary lineage that originated from the land iguana lineage much earlier, about 5.7 million years ago, than the Pleistocene, which is when the rest of the present land iguanas started differentiating throughout the archipelago."

The pink iguana has been placed at the very bottom of the archipelago's land iguana family tree. The researchers believe it emerged even before some of the islands in the area fully formed.