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A new study on Tasmanian devils revealed that a transmissible cancer that has devastated demon populations in recent years has no chance of extinguishing this iconic species.
A new study by Dr. Konstans Wells of Swansea University revealed that it was more likely that the disease would gradually disappear or that the demons would coexist with Tasmanian Devil's Facial Tumor (DFTD) disease.
The DFTD usually kills the majority of the devils it infects and has eliminated about 80% of the wild devils with a continuing decline in extant populations since the first identification of the disease.
An international team of scientists from the United Kingdom, Australia and the United States compared field-collected epidemiological evidence from wild populations collected over a 10-year period in northwestern Tasmania with Simulation studies, which revealed that it was unlikely that the DFTD would continue to cause the continuing decline of the Tasmanian population. devils in the future.
They say that the results of their study, published in Ecology, offers much needed hope that the species, which is the largest marsupial carnivore remaining in the world, does not necessarily disappear because of the DFTD.
Discovered for the first time in northeastern Tasmania in 1996, the DFTD causes the formation of tumors on the face and neck of the animal. Cancer spreads when devils bite their face during fighting, killing the animals between six and twenty-four months.
Dr. Konstans Wells, lead author of the study, said, "Our results suggest that it is unlikely that immediate management interventions are needed to ensure the survival of Tasmanian demon populations. populations of demons after the emergence of the disease does not necessarily translate into long-term decline of the population ".
To explore the long-term results of the DFTD and demon populations, the researchers performed a large number of simulations of the possible spread of diseases in demons. Based on evidence such as current infection rates in the wild, the most likely simulation scenarios were selected to explore the effects of DFTD on demon populations over the next 100 years. The most likely scenarios were those in which the DFTD disappeared (57% of likely scenarios) or coexisted with demons (22% of likely scenarios).
Dr. Rodrigo Hamede of the University of Tasmania, co-author of the study, said: "With more and more obvious evidence that demons are showing signs of adaptation to the DFTD and that so far , the disease did not cause local extinctions, management measures to understand the demon, coping strategies to deal with the DFTD should be considered.
"The complete eradication of the DFTD is not feasible. Therefore, studying long-term interactions between demons and tumors will provide a realistic prognosis for the species while helping us understand important evolutionary processes. This is particularly relevant given the recent outbreak. of a new transmissible cancer – facial tumor of the devil 2 – affecting devil populations in southeastern Tasmania. Devils appear to be susceptible to transmissible cancers, the study of epidemic dynamics and evolutionary responses to such diseases should be a priority. "
Research suggests that management efforts aimed at keeping devil populations should be guided by the changing understanding of the long-term results of the impact of the disease on demons.
Dr. Wells explained, "Management efforts in wild populations that are solely aimed at combating the impact of the DFTD can be counterproductive if they disrupt the long-term forces at work that can eventually lead to stable devil populations that are well able to survive with cancer.
"Wildlife diseases such as the DFTD should not obscure the fact that sufficiently large and undisturbed natural environments are a prerequisite for the survival and management of wildlife such as infectious diseases without human intervention. ".
The study Individual and temporal variation in pathogen load predicts the long-term effects of an emerging infectious disease is published in Ecology.
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