fungus. So, although it is not sure, after the discovery of the fungus and the role it played in amphibian extinctions, it is now believed that the chytrid fungus probably is an important agent of decline for the Queensland frogs, together with climate change (therefore Flannery mentioned the gastric brooding frog in his book), but also pollution, introduced fish and the damming of rivers. Going back to the one feature that sets these frogs apart from the rest: their most unusual reproductive behavior. This has actually made them an iconic example of the great wealth that biodiversity presents to us humans, illustrated by the fact that they starred in an article in Time magazine on ‘nature’s gifts’9. Their gift was that while normally anything that ends up in the stomach will be digested by stomach acids, the tadpoles of these species could sit there comfortably and develop into froglets. The discoverer of the Southern gastric brooding frog, Tyler, together with his colleagues, conducted research on this and found the tadpoles to secrete a substance, prostaglandin E2, that inhibited the secretion of gastric acids. Such a chemical that inhibits the secretion of these acids looked like a promising discovery in finding a treatment to stomach ulcers. Unfortunately the extinction of these species so shortly after their discovery robbed scientists (and the human species in general) of the opportunity to study this chemical and the pathways through which this inhibition works. Their extinction has therefore lead to a hiatus in our medical knowledge that will take a big effort to fill. To all people that believe in the superiority of human technology it teaches a lesson that we still are very dependent on these gifts
of nature for our well-being. This should be no surprise, because these gifts are the outcomes of millions or even billions of years of natural selection; even our large and inventive brains cannot cancel out this advantage. And seeing how many species are alive today and have been alive in the past we should expect that nature has come up with much more ingenious ways of battling diseases, reproducing and adapting to its environment than we can ever dream of. And it becomes clear then, that we cannot mimic these inventions so easily. Not as easily as we can destroy them. References: 1. 2. 3. 4. 5. 6. 7. 8. 9.
Hance, J.L., (2011) Life is good: conservation in an age of mass extinction. Mongabay.com http://news.mongabay.com/2013/0318-gastric-brooding-frog.html
Flannery, T., 2005. The weather makers: how man is changing the climate and what it means for life on earth. Grove Press New York
http://www.arkive.org/southern-gastric-brooding-frog/rheobatrachus-silus/ video-15.html Czechura, G.V. and Ingram, G.J., 1990. Taudactylus diurnus and the case of the disappearing frogs. Memoirs of the Queensland Museum 29: 361-365.
Corben, C.J., Ingram, G.J. and Tyler, M.J., 1974. Gastric brooding: Unique form of parental care in an Australian frog. Science 186: 946-947. http://www.greenleft.org.au/node/5089
Laurance, W.F., 2008. Global warming and amphibian extinctions in eastern Australia. Austral Ecology. 33: 1–9
Plotkin, M.J., 2000. Nature’s Gifts: The Hidden Medicine Chest. Time Magazine
10. MJ Tyler, DJ Shearman, R Franco, P O’Brien, RF Seamark, & R Kelly, 1983. Inhibition of gastric acid secretion in the gastric brooding frog, Rheobatrachus silus. Science, 220 (4597)
54 | FrogLog 21 (4), Number 108 (October 2013)