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Science Notes / Zoology, paleontology

Melting Arctic ice may lead to interbreeding, extinction

As the world heats up and polar ice melts, different types of bears, whales and seals could meet and mate -- but these unions may be far from happy, researchers say. In fact, interspecies sex could lead to the extinction of many endangered Arctic animals, the scientists said in an article published in the journal Nature.

At least 22 species are at risk of hybridizing in 34 different combinations, according to a team led by Brendan Kelly, an Alaska-based evolutionary biologist with the National Oceanic and Atmospheric Administration. The pairings include polar bears and grizzlies; narwhals and beluga whales; and various assortments of seals. Some of those species are listed as endangered or threatened.

Since hybrid offspring are often infertile, maladapted or sickly, much of the genetic biodiversity of the Arctic could be lost. Kelly said the report "is sort of a call-to-arms to encourage our colleagues around the Arctic to recognize this may be going on."

Kelly and his co-authors reached their conclusions after reviewing scientific literature, scouring museums for possible hybrid bones and pinpointing which populations are at risk of running into each other as the Arctic ice shrinks. That ice has separated many animals for as much as 10,000 years, maintaining a barrier to animal movement, and thus interbreeding.

-- Los Angeles Times

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Some velociraptors became plant eaters

It just wouldn't have been the same if the velociraptors in the epic dinosaur movie "Jurassic Park" had been crashing around in the kitchen hunting down a salad bar instead of two children. Velociraptors, part of a group of two-legged dinosaurs known as theropods, were, in fact, strict carnivores, as was the most ferocious theropod of them all, Tyrannosaurus rex.

But, according to research from two paleontologists at Chicago's Field Museum, the diet of their direct ancestors took some surprising turns over the years. As theropods evolved over tens of millions of years, some shifted away from a meat diet, becoming plant eaters or omnivores, eating both plants and meat, according to a study that appeared in the Proceedings of the National Academy of Sciences.

"Most theropods are clearly adapted to a predatory lifestyle, but somewhere on the line to birds, predatory dinosaurs went soft," said Lindsay Zanno, a Field Museum post-doctoral student. "Our common historical image of theropods is out of date."

The study showed that a handful of theropod species -- including velociraptor's direct genetic ancestors -- went from meat eating to plant diets and then inexplicably returned to meat diets after millions of years.

-- Chicago Tribune

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