Wednesday, June 29, 2011

Humans Responsible for Tasmanian Devils' Cancer

credit: Yale Environment 360
US Person reported previously about the epidemic of facial cancer that is wiping out Tasmania's Devil (Sacrcophilus harrisii). {"Tasmanian devil"}. Hope blossomed briefly of cure based on the immunity of one devil from which a vaccine could be made to inoculate the remaining population, but the apparently resistant animal, named "Cedric", eventually succumbed to the cancer. The fierce little marsupials are hotheads, and scientists speculate that the disease is transmitted through bites on the face, making it an extremely rare form of cancer, only one of three known to be transmissible by contact. The resulting cancer tumors have killed about 66% of the population. Some experts believe the disease could make the devil extinct in the wild within 25 years. The devil is endemic to Tasmania, but not always tolerated by man. Like the coyote and the wolf in America, it suffered bounty hunting in the 19th century and strychnine poisoning in the early 20th. So the devil has passed through several population bottlenecks since the arrival of the white man on Tasmania. Now, after sequencing of the animal's genome has been accomplished, biologists think that low genetic diversity caused by man's persecution has left the animal vulnerable to disease. It is widely held by biologists that low diversity is associated with endangerment of a species. A scientist at the University of Sydney said that devils are essentially clones of each other, so tumors are able to pass between without triggering an immune response. The devil has been declared endangered by the Australian and Tasmanian governments, and a captive breeding program established to insure the survival of a cancer free population that could repopulate Tasmania should the wild animals die out.