Will arthritis thwart cane toads?

The wave of pesky cane toads that is spreading across the Australian landscape with a rapacious disregard for the continent's delicate ecological balance might be slowed by a complaint familiar to anyone who travels frequently: a sore back. And one cane toad biologist is suggesting that this weakness may be the key to reining in the invasive amphibian's impact on native Australian species. University of Sydney biologist linkurl:Rick Shine;http://www.usyd.edu.

By | December 2, 2008

The wave of pesky cane toads that is spreading across the Australian landscape with a rapacious disregard for the continent's delicate ecological balance might be slowed by a complaint familiar to anyone who travels frequently: a sore back. And one cane toad biologist is suggesting that this weakness may be the key to reining in the invasive amphibian's impact on native Australian species. University of Sydney biologist linkurl:Rick Shine;http://www.usyd.edu.au/sustainable_solutions/environment/rick_shine.shtml said in a statement today (Dec. 2) that cane toads are getting bigger and faster as they continue to fan out across Australia from Queensland across the Northern Territory; researchers estimate they can travel as far as a kilometer in a single night.
They're not just growing, Shine told linkurl:Reuters,;http://www.reuters.com/article/scienceNews/idUSTRE4B11UT20081202?feedType=RSS&feedName=scienceNews "They have different personalities, different shapes and are developing different physiologies." But they're also encountering problems in their longer spines, Shine said. Reuters quoted Shine saying that, "We are seeing toads in the Northern Territory with spinal arthritis -- big, bony lumps on their spine." These super toads may have evolved themselves into a corner, according to Shine. "The pressure they are putting on their backs, they aren't built for it," he told __The Northern Territory News__. "They've evolved to this point and they've gotten to the edge, but their bodies can't handle any more. They are clearly in discomfort. They are clearly in pain. But they keep moving." Shine also told the paper that he also found bacteria in the joints of the arthritic toads that commonly inhabit the bodies of humans with failing immune systems. "This is a vulnerability. If we can take advantage of this, we can wipe them out," he told __The Northern Territory News__. "Eventually, evolution would favour genes better suited to deal with this, but that is quite a few years away. We have an opportunity now to strike." Related stories:

Comments

Avatar of: null null

null null

Posts: 44

December 4, 2008

Sorry, but no joy here. The bigger toads probably spread faster and hence are selected positively (for), and once they have colonised a new area with eggs it doesn't matter if they die of arthritis. They have already done the colonising and have a head start on the short toads. When the area is densely colonised selection will reverse the situation if shorter toads are fitter, say if they live longer and have greater reproductive success than the long toads. Selection operates for short term reproductive success, and can change direction. It will never reduce fitness. If the environment of a specialised species changes rappidly and drastically then that is another matter.\nHF
Avatar of: Michael Zimmer

Michael Zimmer

Posts: 11

December 4, 2008

I agree. this is not the end of cane toads.\nIt looks more like cane toads adapting to be more suitable for the harsh Australian environment, not less suitable.\n\nLong term survival really isn't a matter if they are still breeding.\n\nThough perhaps lowered immune processes might produce pathogens and parasites more suitable for cane-toad internal environments (which will might be as dooming for native frogs).
Avatar of: anonymous poster

anonymous poster

Posts: 10

December 6, 2008

So it's basically a special case of founder effect, with larger toads with wanderlust spreading faster than smaller homebodies. The selective pressure for these traits result in inbreeding and subsequent higher percentage of recessive traits being expressed in marginal populations (as the fastest expanders out-expand their slower relatives).\n\nIt does make sense, and means the cane toad is adapting to its new environment and becoming _more_, not less, fit, even if some individuals are paying for their success in the form of deleterious recessive traits.\n
Avatar of: anonymous poster

anonymous poster

Posts: 7

December 7, 2008

If the bacteria associated with the longer toad is opportunistic, then it is likely to be selected against over time. Long toads may have an advantage in colonization, but if short toads are more successful reproductivly, they will eventually predominate. Evolution moves toward breeding success. However, if that particular species of bacteria was present in the new territories and has found a new host in which it causes the arthritis, then it might represent a control tool. The question is: Does the bacteria attack arthritic toads or cause arthritis in toads? Ancillary issue: if the bacteria is causing the arthritis, instead of taking advantage of it, it might represent a research direction for human arthritis.

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