something other than "adaptation" driving evolution...,

A computational model of greenish warbler evolution (left) fits real-world patterns of the species (right). Color corresponds to degrees of genetic difference. Image: Martins et al./PNAS

wired | What explains the incredible variety of life on Earth? It seems obvious. Evolution, of course! But perhaps not the evolution most people grew up with.

Some ecologists say the theory needs an update. They’ve proposed a new dynamic driving the emergence of new species, one that doesn’t involve adaptations or survival of the fittest.

Give evolution enough time and space, they say, and new species can just happen. Speciation might not only be an evolutionary consequence of fitness differences and natural selection, but a property intrinsic to evolution, just as all matter has gravity.

“Our work shows that evolution wants to be diverse,” said Yaneer Bar-Yam, president of the New England Complex Systems Institute. “It’s enough for organisms to be spread out in space and time.”


In a March 13 Proceedings of the National Academy of Sciences paper, Bar-Yam and his co-authors, Brazilian ecologists Ayana Martins at the University of Sao Paulo and Marcus Aguiar at the University of Campinas, modeled the evolution of greenish warblers living around the Tibetan plateau.

The warblers are what’s known as a ring species, a rare phenomenon that occurs when species inhabit a horseshoe-shaped range. Genes flow around the ring, passing between neighboring populations — yet at the ring’s tips, the animals no longer interbreed with one another.

By the usual standards, these end populations have become new species. According to the researchers’ model of the process, no special adaptations or differences in reproductive fitness are needed to explain — or at least to computationally replicate — the greenish warblers’ divergence. Fist tap Dale.