Darwin errou de novo: a evolução ocorre rapidamente, é vapt, vupt!!!

Evolution caught in the act: Scientists measure how quickly genomes change
January 1, 2010

Mutations are the raw material of evolution. Scientists at the Max Planck Institute for Developmental Biology in Tubingen, Germany, and Indiana University in Bloomington have now been able to measure for the first time directly the speed with which new mutations occur in plants. Their findings shed new light on a fundamental evolutionary process. They explain, for example, why resistance to herbicides can appear within just a few years.

"While the long term effects of genome mutations are quite well understood, we did not know how often new mutations arise in the first place," said Detlef Weigel, director at the Max Planck Institute in Germany. It is routine today to compare the genomes of related animal or plant species. Such comparisons, however, ignore mutations that have been lost in the millions of years since two species separated.

The teams of Weigel and his colleague Michael Lynch at Indiana University therefore wanted to scrutinize the signature of evolution before selection occurs. To this end, they followed all genetic changes in five lines of the mustard relative Arabidopsis thaliana that occurred during 30 generations. In the genome of the final generation they then searched for differences to the genome of the original ancestor.

The painstakingly detailed comparison of the entire genome revealed that in over the course of only a few years some 20 DNA building blocks, so called base pairs, had been mutated in each of the five lines. "The probability that any letter of the genome changes in a single generation is thus about one in 140 million," explains Michael Lynch.

To put it differently, each seedling has on average one new mutation in each of the two copies of its genome that it inherits from mum and dad. To find these tiny alterations in the 120 million base pair genome of Arabidopsis was akin to finding the proverbial needle in a haystack, says Weigel: "To ferret out where the genome had changed was only possibly because of new methods that allowed us to screen the entire genome with high precision and in very short time." Still, the effort was daunting: To distinguish true new mutations from detection errors, each letter in each genome had to be checked 30 times.

The number of new mutations in each individual plant might appear very small. But if one starts to consider that they occur in the genomes of every member of a species, it becomes clear how fluid the genome is: In a collection of only 60 million Arabidopsis plants, each letter in the genome is changed, on average, once. For an organism that produces thousands of seeds in each generation, 60 million is not such a big number at all.
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Science 1 January 2010:
Vol. 327. no. 5961, pp. 92 - 94
DOI: 10.1126/science.1180677

The Rate and Molecular Spectrum of Spontaneous Mutations in Arabidopsis thaliana
Stephan Ossowski,1,* Korbinian Schneeberger,1,* José Ignacio Lucas-Lledó,2,*, Norman Warthmann,1 Richard M. Clark,3 Ruth G. Shaw,4 Detlef Weigel,1, Michael Lynch2
To take complete advantage of information on within-species polymorphism and divergence from close relatives, one needs to know the rate and the molecular spectrum of spontaneous mutations. To this end, we have searched for de novo spontaneous mutations in the complete nuclear genomes of five Arabidopsis thaliana mutation accumulation lines that had been maintained by single-seed descent for 30 generations. We identified and validated 99 base substitutions and 17 small and large insertions and deletions. Our results imply a spontaneous mutation rate of 7 x 10–9 base substitutions per site per generation, the majority of which are G:CA:T transitions. We explain this very biased spectrum of base substitution mutations as a result of two main processes: deamination of methylated cytosines and ultraviolet light–induced mutagenesis.

1 Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany.
2 Department of Biology, Indiana University, Bloomington, IN 47405, USA.
3 Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
4 Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA.

* These authors contributed equally to this work.

To whom correspondence should be addressed. E-mail: joslucas@indiana.edu (J.I.L.-L.); weigel@weigelworld.org (D.W.)

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NOTA IMPERTINENTE DESTE BLOGGER:

Ao contrário da hipótese transformista proposta por Darwin, o homem que teve a maior ideia que a humanidade já teve - a evolução seria lenta e gradual ao longo de milhões, bilhões de anos, cientistas chegaram à conclusão que a evolução é muito mais rápida do que se pensava: é vapt, vupt!!!

Esqueçamos Darwin por um momento, o homem que teve a maior ideia que a humanidade já teve, mas nunca corroborada pelas evidências, e foquemos nossa atenção para a pesquisa: não seria apenas variação sobre o mesmo tema? Afinal de contas, a Arabidopsis thaliana continuou Arabidopsis thaliana... Um processo microevolutivo, capice???[Comentário adicionado em 04/01/10]