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Evidence of Predictable Evolution

Evidence of Predictable Evolution

Changes in Predator Predictable Faced with Toxic Toad

AwN | When people released Cane Toads, they were primarily interested in themselves, and they were wrong entirely about any purpose there might have been. Eventually they realized that the toads weren't eating the beetles they wanted (the beetles were feet in the air and the toads, well, on the ground) and all of the continental Australian island predators were eating the toxic toads. Giant decreases in Australian toad predators were measured.

So scientists began studying Australia's predators and comparing them with the population of (READ cardiac glycoside resistant) cane toad populations from other continents. They now believe that the evolution of Australia's predators (snakes, goanas etc) will follow a very particular and predictable path, eventually leading to nearly complete resistance amongst their populations. 

It is an interesting result, but I wouldn't really say it is altogether surprising. Not just because I read a while back that the Sabertooth Tiger was said to have evovled seperately multiple times. This situation has a quite specific problem for predators of the toad and it tends to lead to specific solutions.

My speculation is a little more diffuse, but when you consider eternity it is hard to get around:

Cyclical Human Evolution | Spirit and Science

What becomes even more interesting is if you extrapolate this idea out to an infinite universe and extremely long time periods. You can look at this in a philosophical/spiritual sense, or a practical one like the toad. Could the universe create human's over and over, in its eternity, to solve the infinite problem of knowing itself? That is humans come about often to fill basic voids in the subject, object dichotomy that is basic to the existence of anything. If you wish for more earthly examples you needn't look any further than the current evolution of the human and to guess at the main purpose of that evolution, and whether it might be replicated. Perhaps as the human (or ape?) begins to trade strength and endurance for knowledge the process is unstoppable. I'm digressing from the toad though, and I don't want to steal his thunder...

The article gets sligthly technical but it is readable even if you skim over the scientific details, unless of course you like that sort of thing!

Predictable evolution: bad news for toads, good news for their predators

“Throughout my education, I was taught that evolution follows a more or less random pattern, and is rarely predictable,” said Dr Ujvari. “I was surprised to find such a clear pattern of predictable evolution across the entire animal kingdom.”

This study revealed that a wide variety of unrelated animals -- insects, amphibians, reptiles, and mammals -- can evolve the same solution to a specific problem in parallel.

“The repeatability of this process demonstrates that evolution can proceed along highly predictable paths at the molecular level,” said Dr Ujvari. “Our case study has important implications for conservation biology, by providing a simple predictive framework for assessing the potential vulnerability of native fauna to the introduction of toxic invasive species.”

The Guardian

Image:  Cane toad, Rhinella marina, is native to Central and South America. This poisonous toad is an invasive species in Australia and other places where it was introduced by people. Photograph: Beata Ujvari et al/PNAS 2015


Beata Ujvari, Nicholas R. Casewell, Kartik Sunagar, Kevin Arbuckle, Wolfgang Wüster, Nathan Lo, Denis O’Meally, Christa Beckmann, Glenn F. King, Evelyne Deplazes, and Thomas Madsen (2015). Widespread convergence in toxin resistance by predictable molecular evolution, Proceedings of the National Academy of Sciences, published online on 7 September 2015 ahead of print | doi:10.1073/pnas.1511706112

also cited:

P. J. Mayes, G. G. Thompson, P. C. Withers (2005). Diet and foraging behaviour of the semi-aquatic Varanus mertensi (Reptilia : Varanidae), Wildlife Research32(1):67–74 | doi:10.1071/WR04040 [free]

Beata Ujvari, Hee-chang Mun, Arthur D. Conigrave, Alessandra Bray, Jens Osterkamp, Petter Halling and Thomas Madsen (2013). Isolation breeds naivety: Island living robs Australian varanid lizards of toad-toxin immunity via four-base-pair mutation, Evolution 67(1):289–294 | doi:10.1111/j.1558-5646.2012.01751.x[£]

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