Darwin's finches seen as still changing today
EVOLUTION
Want to see evolution in action but don't have hundreds of thousands of years for observations? If you're watching some of the finches Charles Darwin famously observed on the Galapagos Islands, all you need is a good pair of binoculars, a bit of luck, and some patience, according to a new study on how competition can drive evolution in just a few years. Large ground finches intruded on the territory of medium-sized ground finches on Daphne Major Island in 1982. In the two years following a 2003 drought, as competition for seeds dramatically increased, the length of the smaller finch's beak shrank by 5 percent, better adapting it to eat smaller seeds. The study, conducted by the husband-and-wife team of Peter R. and B. Rosemary Grant over 33 years , marks the first time such a phenomenon -- known as character displacement -- has been observed in real time in the wild.
BOTTOM LINE: The combination of new competition and a food shortage triggered an evolutionary change in one small bird. ``This is something that was appreciated by Darwin, even though he had no understanding of genetics," Peter Grant said in a recorded statement.
CAUTIONS: The study is the first of its kind and needs to be replicated to definitively confirm that evolution occurs in this way.
WHAT'S NEXT: The authors hope their research will provide a template for other evolutionary biologists.
WHERE TO FIND IT: Science, July 14, 2006.
PHIL McKENNA
DIABETES
Researchers find a link between Type 2, glaucoma
A large new study has confirmed the previously suspected link between diabetes and the most common form of glaucoma, one of the leading causes of blindness in the United States. Harvard University researchers looked at data collected on more than 76,000 women over 20 years and found that participants with Type 2 diabetes had a two-fold increased risk for glaucoma, even after other factors were taken into account, including family history of glaucoma, hypertension, weight, smoking, and physical activity. ``People with Type 2 diabetes need to be screened" for glaucoma, said Louis Pasquale of Harvard Medical School, the study's lead author. Because rates of Type 2 diabetes are expected to climb with the aging of the US population and the widening of its waistline, he predicted an increase in glaucoma in the coming decades. The study also found, however, that obesity appeared to have a protective effect against glaucoma, with heavier individuals with Type 2 diabetes less likely to develop glaucoma than their slimmer counterparts.
BOTTOM LINE: Women with diabetes should get their eyes checked regularly, because they are more likely than nondiabetics to develop glaucoma, a leading cause of blindness.
CAUTIONS: It's possible that women with diabetes -- who are already counseled to get regular vision checkups -- are more concerned about their eyesight than those without the disease, so they receive better medical care and are more likely to be diagnosed with glaucoma.
WHAT'S NEXT: The researchers will study individual body chemicals involved in diabetes to see if any of them are associated with glaucoma.
WHERE TO FIND IT: Ophthalmology, July 2006.
NAILA MOREIRA
ENERGY
Biodiesel made from soybeans wins fuel fight with ethanol
Searching for an alternative to the skyrocketing cost of gasoline, researchers from the University of Minnesota compared diesel fuel made from soybeans with ethanol made from corn in terms of the energy it takes to produce them, their environmental impacts, and their production costs. They found that biodiesel provides 93 percent more energy than is used to produce it and cuts greenhouse gas emissions by 41 percent, compared with regular diesel fuel emissions. Ethanol fared less well, providing only 25 percent more energy than it takes to manufacture and, compared with gasoline, producing just 12 percent less greenhouse gases while raising the emissions of five air pollutants. Producing biodiesel also requires far fewer fertilizers and pesticides -- which cause water pollution and release greenhouse gases -- than ethanol. But both fuels require subsidies to be competitive with current gasoline and diesel fuel prices, and neither can be produced at a large enough scale to help offset more than 3 percent of current petroleum use, the researchers found. But they are good ``first-generation" biofuels to use while research continues into other plant sources of fuel, such as prairie grasses, said biologist and co-author Jason Hill.
BOTTOM LINE: Biodiesel and ethanol both have many limitations, but are a good first start toward replacing petroleum with plant-based sources of fuel.
CAUTIONS: This study did not account for the costs of converting forest and other land into agricultural land to increase biofuel supplies.
WHAT'S NEXT: Further research is required to improve plant production and fuel conversion technologies.
WHERE TO FIND IT: Proceedings of the National Academy of Sciences, July 12, 2006.
ELIZABETH DOUGHERTY 