How predictable is evolution?


Understanding how and why diversification occurs is important for understanding why there are so many species on Earth. In a new study published on 19 February in the open access journal PLOS Biology, researchers show that similar—or even identical—mutations can occur during diversification in completely separate populations of E. coli evolving in different environments over more than 1000 generations. Evolution, therefore, can be surprisingly predictable.

The experiment, conducted by Matthew Herron, research assistant professor at the University of Montana, and Professor Michael Doebeli of the University of British Columbia, involved 3 different populations of bacteria. At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the carbon sources. Herron and Doebeli were able to sequence the genomes of populations of bacteria frozen at 16 different points during their evolution, and discovered a surprising amount of similarity in their evolution.

“In all three populations it seems to be more or less the same core set of genes that are causing the two phenotypes that we see,” Herron said. “In a few cases, it’s even the exact same genetic change.”

Recent advances in sequencing technology allowed Herron and Doebeli to sequence large numbers of whole bacterial genomes and provide evidence that there is predictability in evolutionary diversity. Any evolutionary process is some combination of predictable and unpredictable processes with random mutations, but seeing the same genetic changes in different populations showed that selection can be deterministic.

“There are about 4.5 million nucleotides in the E. coli genome,” he said. “Finding in four cases that the exact same change had happened independently in different populations was intriguing.”

Herron and Doebeli argue that a particular form of selection—negative frequency dependence—plays an important role in driving diversification. When bacteria are either glucose specialists or acetate specialists, a higher density of one type will mean fewer resources for that type, so bacteria specializing on the alternative resource will be at an advantage.

“We think it’s likely that some kind of negative frequency dependence—some kind of rare type advantage—is important in many cases of diversification, especially when there’s no geographic isolation,” Herron said.

As technology advances, Herron believes that similar experiments in larger organisms will soon be possible. Some examples of diversification without geographic isolation are known in plants and animals, but it remains to be seen whether or not the underlying evolutionary processes are similar to those in bacteria. Via How predictable is evolution?.

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One Response to How predictable is evolution?

  1. Geza Zake says:

    How predictable is evolution? – Is the question posed by traditional evolutionists always from the point of evolution of species, but always with a speech about evolution of small animals, such as bacteria and viruses. The evolution of macro species such as species of flora and fauna did not speak, except that instead of them seeing the evolution of devolution of the disappearance of many species on the planet Earth. Even more difficult situation occurs when we asked about the evolution of man and mankind? There usually reigns “silence,” or someone trying to say that traditional evolution disappears and emerges a new sociological.
    In such a frame of mind of people are beginning to emerge, including myself, who start to talk about the further evolution of man and mankind through the prism of creativity and change that it brings human creativity and technology. Many say that these changes are exponential and that is in front of our eyes rapidly formed a new gigantic beings of humanity which becomes more obvious autonomously vast terrestrial and extraterrestrial creature with the qualities a man from physical to mental and intellectual. Plenty of evidence that such a process takes place and that such a huge creature emerges which whom I have gave the name of Homoteras. The Global Brain – super brain it is our reality. We coll it Internet. In the context of the global evolution evolutionists must draw attention to a little better fact which says that man from object of evolution became subject of evoluction. In light of these facts I suggest that the evolutionists begin to deal more with the evolution of man and humanity less with the evolution of E Coli.

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