A threatened marsupial offers the most compelling case yet for encouraging teen pregnancy — extinction.
The existence of Tasmanian devils, the world's largest carnivorous marsupial, is threatened by increasing incidence of "devil facial tumor disease," or DFTD. No one knows the cause of the disease — infectious cancers found around the mouth spread between animals by biting, primarily during mating — that scientists say is consistently fatal.
With a spectacular olfactory system that detects food a kilometer away, jaws more powerful than a tiger's and capable of running faster than humans on rough terrain, the wild population of Tasmanian devils, as a result of DFTD, may face possible extinction in the next 25 years.
While environmental pressures will affect the life history of all species in the wild, the devils' response to this threat, according to a study released July 14 by the National Academy of Sciences, is a first of its kind — "the first known case of infectious disease leading to increased early reproduction in a mammal."
The team of Australian researchers, headed by Menna E. Jones, collected data from five different population sites off the island of Tasmania. They theorize that in the last decade, DFTD, which now afflicts more than half the population and kills within five months of manifestation, has lead to unusually early breeding.
With a typical lifespan of five to seven years, female devils would normally begin breeding at age 2, and would produce a litter annually for three years. With this disease, they are now mating only once. The scientists say they observed "a 16-fold increase in the proportion of individuals exhibiting precocious sexual maturity."
The babies, up to 20, are born after 30 days gestation and like all marsupials, are very tiny, in this case the size of a matchstick. However, the devil's marsupial pouch can only accommodate four young. Between two to four babies will be born the second time.
Once infected with DFTD, females may not survive to rear even one litter, and in areas of DFTD, the researchers found the devil populations reduced by nearly 90 percent.
Infectious disease experts suggest the decimation of the species could be averted if natural immunity develops (which the rate of death seems to rule out) or if treated through a vaccine if the cancer is found to be associated with a virus. Earlier research suggests a lack of genetic diversity has made the devils more susceptible to disease, and experts who cut their teeth studying other low-diversity species like cheetahs and mammoths have been called in to consult.
A research program called Save the Tasmanian Devil has been established to investigate the disease and identify management options.