Urban development can isolate wildlife populations and promote inbreeding, according to a genetic study of animals in the Santa Monica Mountains by researchers at the National Park Service and the U.S. Geological Survey. Researchers studied three commonly found species of lizards and a small songbird, the wrentit, comparing the DNA of animals collected throughout the now-isolated scrubland patches and parks surrounding Thousand Oaks and State Route 23 — an area that was a single, mostly contiguous wilderness only 50 years ago. The data showed that the populations of lizards and wrentits have become disconnected and isolated as their natural habitats became divided and fragmented by roadways and housing. As the animals are unable to cross these urban barriers, they begin to inbreed and lose their genetic diversity. Decreased genetic diversity may increase a species’ chance of extinction.