ScienceDaily (July 2, 2010) - As global warming threatens many animal species with extinction, the already destructive cane toad is set to flourish with increasing temperature, say Australian scientists.
"The negative effect of high temperature does not operate in Cane Toads, meaning that toads will do very well with human induced global warming," explains Professor Frank Seebacher from the University of Sydney.
Unlike fish and other cold-blooded creatures, whose oxygen transport system suffers at high temperatures, the cardiovascular system (heart and lungs) of Cane Toads performs more efficiently.
The researchers present their new findings at the Society for Experimental Biology Annual Conference in Prague on Friday 2nd July 2010.
When tested over an ambient temperature range of 20-30˚ C [up to 86˚ F], Cane Toads acclimatised perfectly to increased temperatures and resting oxygen demands remained constant.
Furthermore, the efficiency of the oxygen transport system in the Cane Toad increased with increasing temperature, showing not only an ability to function over a broad thermal range but remarkably, a preference for higher temperatures.
This is in contrast to previous studies suggesting an increase in temperature results in a higher basic oxygen demand, coupled with decreased efficiency of the circulation system, leading to oxygen starvation.
"Warmer temperatures are advantageous and there is no indication that high temperatures limit oxygen delivery," explained Professor Seebacher.
The scientists say this positive effect may also apply to other anurans (the class of amphibians that includes frogs and toads), but more research needs to be done to find out.
"The impact of global warming doesn't have to be negative. Global average temperatures at present may in fact be cooler than many animals would like," explained Professor Seebacher.
"There will be winners and there will be losers but that needs to be judged on a species by species basis," added Dr Craig Franklin, co-author of the research.
The Cane Toad can adapt its physiology in response to a changing environment repeatedly and completely reversibly many times during its lifetime.
Originally introduced as agricultural pest-control due to its voracious appetite for the Cane Beetle, populations have now escalated out of control. The skin of the Cane Toad is toxic1 and deadly when ingested by other animals, many of them native predators.
1And they were doing so well. The skin is harmless. It's the toad's parotid glands, which secrete a toxic chemical, that are the problem. Although some snakes are developing a resistance to the toxin, while some birds have learned to flip the toad over to get at its tasty insides, thus avoiding the toxin.
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