Climate big player in Patagonian ice age mammal extinction 12,000 years ago

Anonymous — Fri, 17 Jun 2016 22:45:04 +0000

Climate big player in Patagonian ice age mammal extinction 12,000 years ago Anonymous (not verified) Fri, 06/17/2016 - 16:45

Jim Scott

A study led by the University of Adelaide and including the ��񱦵� indicates giant ice age-era mammals that roamed Patagonia until about 12,300 years ago were finally felled by a rapidly warming climate, not by a sudden onslaught of the first human hunters.

Jessica Metcalf

Led by the University of Adelaide’s Australian Centre for Ancient DNA (ACAD), the study revealed that it was only after the climate warmed, long after humans first arrived in Patagonia, that the large animals known collectively as megafauna suddenly died off. The victims included a mind-bending menagerie of elephant-sized sloths, saber-toothed cats, horses, camels and gigantic bears.

The timing and cause of the rapid extinction of the megafauna in Patagonia – a geographic region at the base of South America that includes the lower sections of Argentina and Chile – has been a mystery for decades. The new study was published today in the journal Science Advances.

“Patagonia turns out to be the Rosetta Stone – it shows that human colonization didn’t immediately result in extinctions, but only for as long as it stayed cold,” said Professor Alan Cooper, study leader and ACAD director.

“Instead, more than 1,000 years of human occupation passed before a rapid warming event occurred, and then the megafauna were extinct within a hundred years,” said Cooper. “It was humans, but they needed the climate to warm first.”

CU-Boulder Senior Research Associate Jessica Metcalf, lead study author and a former postdoctoral researcher at ACAD, said the study helps to clear up a muddy picture of now-extinct South American megafauna.

“The DNA and age of bones from South American megafauna showed the extinctions occurred long after human arrival there and coincided with climate warming,” said Metcalf, of the ecology and evolutionary biology department. “We found that members of the camel family, for example, considered resilient survivors of the last ice age, suffered huge losses in genetic diversity.”

The researchers studied ancient DNA they extracted from bones and teeth found in caves across Patagonia and Tierra del Fuego to trace the genetic history of the ice age mammals. As part of the research they also radiocarbon dated the samples, more than doubling the number of existing radiocarbon dates for Patagonia megafauna, she said.

The pattern of rapid human colonization through the Americas, coinciding with contrasting temperature trends on each continent, allowed the researchers to untangle the relative impact of human arrival and climate change.

Restoration of the extinct short-faced bear (Arctodus simus). Photo courtesy of Wikipedia.

The earliest Americans are thought by most scientists to have traveled from northeast Asia over the Bering Land Bridge and into present-day Alaska roughly 16,000 years ago.

“The Americas are unique in that humans moved through two continents, from Alaska to Patagonia, in just 1,500 years,” said Professor Chris Turney of University of New South Wales, a study co-author. “As they did so they passed through distinctly different climate states – warm in the north and cold in the south. As a result, we can contrast human impacts under different climate conditions.”

As part of the study the team amplified fragments of ancient DNA and pieced them together like a high-tech jigsaw puzzle to reveal genetic histories of the megafauna.

The study involved a host of other institutions including the University of Magallanes in Patagonia and the University of Oxford in England.

“This is a good example of how researchers from different disciplines and institutions can work together to answer long-standing and important questions in science,” said Metcalf.

Jim Scott is senior science editor for the CU Office of News Services.

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Helping students and imperiled wildlife, one at a time

Anonymous — Thu, 28 Apr 2016 19:24:21 +0000

Helping students and imperiled wildlife, one at a time Anonymous (not verified) Thu, 04/28/2016 - 13:24

CU News Center

An evolutionary biologist, Professor Andrew Martin has long been involved in genetic studies and conservation efforts on behalf of wildlife in peril, from greenback cutthroat trout and great white sharks to desert pupfish and prairie dogs.

In 2014, for example, he teamed with CU-Boulder Senior Research Associate Jessica Metcalf and biologists from six state and federal agencies on a recovery effort involving the greenback cutthroat trout, Colorado’s endangered state fish.

Martin helping to reintroduce endangered greenback cutthroat trout fingerlings into Zimmerman Lake west of Fort Collins in August 2014

“Being a part of a large, collaborative team that is helping to bring a species back from near-extinction is a great experience,” says Martin of CU-Boulder’s Department of Ecology and Evolutionary Biology. “It feels good for the soul.”

But Martin is not just a top-tier scientist. Because of his exceptional abilities and passion to integrate his teaching and research, he has been named one of two CU President’s Teaching Scholars for 2016 by President Bruce Benson. The second scholar is Dr. Jeannette Guerrasio of the University of Colorado School of Medicine at the Anschutz Medical Campus in Aurora.

“It’s nice to be recognized for things we do as faculty members,” says Martin. “But I don’t view this award as a recognition of my efforts – it is for all of the remarkable and dedicated people in my department and across campus who are advancing the craft of teaching.”

He was cited for being an “innovative, highly effective educator” who helps faculty to transform teaching, encouraging experimentation with various methods to better engage students.

“We have amazing faculty learning groups on campus that regularly get together to talk about how to improve education,” he explains. “We are enrolling more students in the sciences at CU-Boulder, and they are becoming more successful.”

In addition, he has led K-12 workshops for teachers, including some in the Boulder Valley School District, on effective teaching methods based on data collection and analysis. He also is a fan of using classroom “clickers” for feedback on how well the students are understanding biological and ecological concepts during his lectures.

Whether he is in the field, classroom or lab, Martin mentors graduate students, undergraduates and high school students. One of his outreach efforts is a “citizen science” project that began as a science project by a Fairview High School student in Boulder who found found antibiotic-resistant bacteria, a global health threat, were common in the local watershed.

Martin and his colleagues rely on high-tech gene sequencing techniques to assemble evolutionary trees that help the scientists better understand address conservation concerns. Such tools aided Metcalf and Martin in determining the genetic makeup of the true greenback cutthroat from fish collected in the mid-1800s during the Gold Rush and then archived in natural history museums around the country.

The findings initiated a recovery program for bringing back the native fish into the waters of the South Platte River basin, its historical haunts.

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