Biodiversity

Publishing in the journal Nature, a group of 29 scientists have established a comparative scale for rating the immediate threat posed by nine environmental hazards--everything from climate change to ocean acidification. And while our warming climate gets most of the attention, more immediate problems may be brewing in our intensifying lack of biodiversity and out-of-whack nitrogen cycle.

Now that scientists can analyze the DNA of any species, they are discovering that many animals that look indistinguishable are actually quite different at the genetic level-different enough to be classified as separate species. That means there may be a lot more biological diversity on Earth than meets the eye.

For example, biologists at the University of California, Berkeley, recently reported the discovery of a new species of Mexican salamander, Lineatriton, that looks identical to another species living several hundred miles away. Only DNA testing can tell them apart.