Thursday, July 11, 2013

State of evolution

YESTERDAY: Doctoral student in biology Daniel Scantlebury of the University of Rochester examined the evolutionary history of 7 groups of reptiles and amphibians in Madagascar, including the giant leaf-tailed gecko (IMAGE ABOVE), which branched out over the 88 million years since the island was formed. Madagascar is known for the diversity of its flora and fauna, but the study shows that the accelerated adaptive radiation, as it is called, may have reached its limit: "[W]hen all the ecological niches are filled, evolution slows down to its regular pace. And Scantlebury's research indicates that that's what's happening in Madagascar: all seven of his examined species have declined in their speed of evolution after their initial burst."

TODAY: Biologist Charles Brown of the University of Tulsa co-authored a study in March suggesting that starlings living near the highway have developed shorter wingspans that allow them to better maneuver and avoid becoming roadkill: "It's possible to observe evolution occurring in contemporary time. Over a 30-year period, we've seen natural selection for birds that are able to avoid being hit by cars. The work also illustrates that some animals can adapt relatively quickly to these urbanized environments."

TOMORROW: Ecologist and evolutionary biologist John J. Wiens of the University of Arizona compared the rates of adaptability of 540 living species of terrestrial vertebrates - including amphibians, reptiles, birds, and mammals - to rates of climate change projected for the end of this century. His calculations indicate that many species (particularly those unable to move to new habitats) will be unable to evolve quickly enough to avoid extinction. "We found that on average, species usually adapt to different climatic conditions at a rate of only by about 1°C per million years. But if global temperatures are going to rise by about 4° over the next hundred years as predicted by the Intergovernmental Panel of Climate Change, that is where you get a huge difference in rates. What that suggests overall is that simply evolving to match these conditions may not be an option for many species."

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