Genetics Explained The Darkening Of Darwinian Butterflies To The Industrial Era


A classic example of the operation of evolution mechanisms received a genetic explanation. Mutation associated with the "industrial" darkening of the wings of birch spin, turned out to be inserted into the gene, controlling the growth and division of cells.Genetics Explained The Darkening Of Darwinian Butterflies To The Industrial Era
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The history of birch spdens (Biston Betularia) became one of the classical examples of driving selection in evolution. Until XIX in. These butterflies had a white-gray painting that helped them mimicry under the birch birch. However, almost black melanistic forms began to appear increasingly: an industrial revolution, which was based on coal burning, led to emissions to the atmosphere of large quantities of soot. Berez’s trunks dark, and because only darker butterflies could still effectively hide them from birds.

This process called industrial melanism, manifested itself more than a century. By 1950, there are already about 90% of the spiders living near the large industrial centers of Great Britain were black. However, as environmental standards and transfer of production from developed countries in developing local air quality began to improve. Already in the 1970s, the usual "ripples" birch spiders began to return, and today they make up 90% of populations.

Unfortunately, this bright evolutionary story remains incomplete: the genetic basis of rapid changes occurring with butterflies has not yet been known. Only in 2011. Researcher from Liverpool University of Ilik Saccheri and his colleagues managed to localize a possible mutation on one of the insect chromosoma. In his new work, the results of which publishes the Nature magazine, they set the DNA sequence of this suspicious site from the "white" and "black" spiders, finding as many as 87 differences. Expanding the search, the authors analyzed these 87 mutations on a wider sample – 283 "White" and 110 "black" butterflies. And only then guilty in change coloring the mutation was found.

In 95% of melanyst spinings there is a small insert, a mobile genetic element that appeared in the Cortex gene described for the drosophyl, which he participates in cellular division and embryonic development. This option was unexpected for scientists. So far they cannot explain exactly how the Cortex mutation could have affected the color of the wings. However, the possible mechanism is still available.

The fact is that the coloring of the butterfly wings is determined by tiny scales, which cover them like a mosaic. The appearance and growth of scales of different colors does not occur simultaneously, and if Cortex affected their development, he could change the color of the spdens.

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