Rapid Darwinian Evolution
Simply stated, Darwin told us that evolution revolves around the survival of the fittest – those least fit don’t make it, and therefore they don’t leave offspring. Those most fit will prosper, and their offspring will inherit the genes that gave them that advantage.
Most experts would say that evolution is a slow process. Some say it can happen rapidly (see “punctuated equilibrium“). I figure both are correct – it can happen fast, medium or slow. The more extreme the circumstances, the more rapid the evolution.
In late 2007 SciAm published an opinion piece that highlights just how rapidly evolution can occur:
Brought to Queensland in 1935 to combat beetles infesting sugarcane fields, the [Cane]toads have spread out from their point of entry like the shock waves of a bomb, warty legs and oversize tongues jettisoned into every conceivable ecological crack.…Recent research… has shown that the toads are evolving as they spread, perfecting their ability to adapt to the Australian landscape. The toads at the front edge of the invasion now have smaller bodies, reduced toxicity and relatively longer legs, apparently because individuals with those traits were having greater success. The native fauna has evolved in response: the mouths of some snake species are getting smaller, for instance, because so many of the snakes with big mouths were eating the poisonous cane toads and dying off.
In a global cataclysm scenario, evolutionary pressures can become extreme. Larger, less-populous species are more likely to become extinct (less places to hide, less numbers). The butterfly effect of this can wreak havoc on the what was previously a well-balanced scenario. Changed landscapes and climates can suddenly create challenges, giving advantage to those best suited to the changed situation.
Unless we have scientists observing the the most extreme circumstances nature can toss our way, we will be unable to realise how rapid evolution can be – we will be unable to realise that gaps in the evolutionary tree come down to the sheer speed of the evolution itself.
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