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Week of January 14, 2013

Scholarship & Creative Work

Climate warming unlikely to cause near-term extinction of ancient Amazon trees

A new genetic analysis has revealed that many Amazon tree species are likely to survive human-caused climate warming in the coming century, contrary to previous findings that temperature increases would cause them to die out.

However, the authors of the new study warn that extreme drought and forest fires will impact Amazonia as temperatures rise, and the over-exploitation of the region’s resources continues to be a major threat to its future. Conservation policy for the Amazon should remain focused on reducing global greenhouse-gas emissions and preventing deforestation, they said.

This enormous kapok tree provided some DNA for the genetic study by U-M evolutionary biologist Christopher Dick and his colleagues. The species, Ceiba pentandra, was the youngest species found in the study, less than 1 million years old. Photo by Robin Foster, the Field Museum.

The study by U-M evolutionary biologist Christopher Dick and his colleagues demonstrates the surprising age of some Amazonian tree species — more than 8 million years — and thereby shows that they have survived previous periods as warm as many of the global warming scenarios forecast for the year 2100.

The paper appeared Dec. 13 in the journal Ecology and Evolution. The new study is at odds with earlier papers, based on ecological niche-modeling scenarios, which predicted tree species extinctions in response to relatively small increases in global average air temperatures.

“Our paper provides evidence that common Amazon tree species endured climates warmer than the present, implying that — in the absence of other major environmental changes — they could tolerate near-term future warming under climate change,” said Dick, an associate professor of ecology and evolutionary biology and acting director of the U-M Herbarium.

Dick and his colleagues used a molecular clock approach to determine the ages of 12 widespread Amazon tree species, including the kapok and the balsa.

The researchers determined that nine of the tree species have been around for at least 2.6 million years, seven have been present for at least 5.6 million years, and three have existed in the Amazon for more than 8 million years.

Women drivers outnumber men, but still drive less

Although women drivers now outnumber male motorists, men still account for the majority of the driving on America’s roads—albeit at a declining rate, says a U-M researcher.

Using data from the Federal Highway Administration, Michael Sivak, a research professor at the U-M Transportation Research Institute, examined changes in the gender demographics of U.S. drivers from 1963 to 2010.

In 1963, males represented 60 percent of all drivers. Today, that number is just under 50 percent. But when accounting for average annual miles driven, men make up 59 percent of drivers on the road — down considerably from 76 percent nearly 50 years ago.

“Currently, females with a driver’s license slightly outnumber males,” Sivak said. “However, because females drive less than males, the overall likelihood that a given driver on the road today is a female is still less than 50 percent.”

Since the 1960s, the average distance driven has increased 33 percent for men, but 89 percent for women. Back then, the average male drove twice as many miles as the average female. Today, the ratio is down to one-and-a-half times.

“The observed gender trends in driver licensing will likely have major implications on the extent and nature of vehicle demand, energy consumption and road safety,” Sivak said. “This is the case because females are more likely than males to purchase smaller, safer and more fuel-efficient vehicles than males. They also drive less and tend to have a lower fatality rate per distance driven.”

Corporations favor elite nonprofits

Businesses are good for nonprofits, but they are especially good for nonprofits that directly benefit the corporate elite such as art institutes, symphony orchestras and private schools, according to research from U-M.

The study asked how locally headquartered corporations influenced the growth of two different types of nonprofit organizations — those oriented to the elite and those focused more broadly on social welfare — in the largest 100 U.S communities from 1987 to 2002.

Gerald Davis, a professor at the Stephen M. Ross School of Business, said that the study shows that nonprofits appealing to the elite flourish in communities that have a strong base of corporations working together.

“Corporations are vessels for aggregating resources,” Davis said. “We find that across every major American city, the resources of the corporate sector are most beneficial for elite-oriented nonprofits.”

Older cities tend to have a stronger connection between the corporate and nonprofit communities, he said.

“Cities whose business communities ‘grew up’ after the turn of the 20th century are really different from cities established earlier,” Davis said. “Older communities laid down traditions like giving to charity. And then they were reinforced every year.”

Social welfare-oriented organizations such as food banks, homeless shelters and women’s shelters saw no additional benefit from a large concentration of corporations in a community, said study co-author Christopher Marquis, a Harvard Business School professor and Ross School alum.

“Our results are thus generally consistent with speculation that philanthropy may actually be a vehicle to benefit elite interests,” Marquis said. “Corporate effects on elite-oriented nonprofits are enhanced when there is a community structure in place that organizes and validates the elite.”

Davis notes the example of the Twin Cities of Minneapolis/St. Paul with their Five Percent Club. Corporations need to give 2-5 percent to charity to gain admittance to the Minnesota Keystone Program.

“Well-connected social elites can enforce those norms,” he said. “When you know you’re going to see your colleagues every month at the club or the board meeting, you’re more inclined to follow the local standards around giving back.”

An older Vega: New insights about the star all others are measured by

Vega, a star astronomers have used as a touchstone to measure other stars’ brightness for thousands of years, may be more than 200 million years older than previously thought. That’s according to new findings from U-M.

The researchers estimated Vega’s age by precisely measuring its spin speed with a tool called the Michigan Infrared Combiner, developed by John Monnier, associate professor of astronomy in LSA.

MIRC collects the light gathered by six telescopes to make it appear to be coming through one that’s 100 times larger than the Hubble Space Telescope. It’s installed at the Georgia State Center for High Angular Resolution Astronomy Array located on Mount Wilson, California.

The tool boosts resolution so astronomers can zoom in, relatively speaking, to observe the shape and surface characteristics of stars that would otherwise look like mere points even through the most powerful telescopes. By tracking stars’ surface characteristics, scientists can calculate how fast they rotate and deduce their inner workings.

Vega is a summer star in the Northern Hemisphere, just visible toward the west at sunset. It’s the brightest star in the constellation Lyra. At 25 light years away, Vega is close on cosmic scales. A light year is the distance light travels in one year.

About six years ago astronomers discovered that Vega is rotating so fast it’s nearly flinging itself apart. They haven’t been able to agree on many of the related details, however. One of the debates centers on Vega’s exact rotation rate, which is essential to gauge both its mass and age.

With MIRC’s unprecedented resolution, Monnier and his colleagues have taken steps to rectify competing estimates of Vega’s rotation rate and other properties The new findings indicate that the star rotates once every 17 hours, rather than once every 12.

Capturing circulating cancer cells could provide insights into how disease spreads

A glass plate with a nanoscale roughness could be a simple way for scientists to capture and study the circulating tumor cells that carry cancer around the body through the bloodstream.

Engineering and medical researchers at U-M have devised such a set-up, which they say takes advantage of cancer cells’ stronger drive to settle and bind compared with normal blood cells.

Circulating tumor cells are believed to contribute to cancer metastasis, the grim process of the disease spreading from its original site to distant tissues. Blood tests that count these cells can help doctors predict how long a patient with widespread cancer will live.

As important as the castaway cells are, scientists don’t know a lot about them. They’re rare, at about one per billion blood cells. And they are not all identical, even if they come from the same tumor. Existing tools for isolating them only catch certain types of cells — those that express specific surface proteins or are larger than normal blood cells.

The researchers say their system could likely trap these stealth cancer stem cells — a feat no research team has accomplished yet.

“Our system can capture the majority of circulating tumor cells regardless of their surface proteins or their physical sizes, and this could include cancer progenitor or initiating cells,” said Jianping Fu, assistant professor of mechanical engineering and biomedical engineering and a senior author of a paper on the technique published online in ACS Nano.

Fu and his engineering colleagues teamed up with U-M senior cancer researcher and breast cancer clinician Dr. Sofia Merajver and her team. This multidisciplinary group believes that while the device could one day improve cancer diagnosis and prognosis, its first uses would be for researchers to isolate live circulating tumor cells from blood specimens and study their biological and physical properties.

— Nicole Casal Moore, News Service

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