DNA of 'Evolution Canyon' fruit flies reveals drivers of evolutionary change

Jul 07, 2014
DNA of 'Evolution Canyon' fruit flies reveals drivers of evolutionary change
The south-facing slope of "Evolution Canyon" is tropical and may receive eight times as much sun, while the north-facing slope is darker, like a European forest. Animals adapt depending on whether they live on the drier, hotter side of the canyon, or the more humid, cooler side. Credit: Institute of Evolution, Haifa University

Scientists have long puzzled over the genetic differences between fruit flies that live hardly a puddle jump apart in a natural environment known as "Evolution Canyon" in Mount Carmel, Israel.

Now, an international team of researchers led by scientists with the Virginia Bioinformatics Institute at Virginia Tech has peered into the DNA of these closely related flies to discover how these animals have been able to adapt and survive in such close, but extremely different, ecologies.

One reason lies in a startling abundance of repetitive DNA elements that, until recently, were considered little more than unused letters in a word game. The explanation will be published this week in the Proceedings of the National Academy of Sciences.

"We've come to understand that not all repeat sequences are junk DNA," said Pawel Michalak, an associate professor at the Virginia Bioinformatics Institute. "These repetitive sequences are increasingly being recognized as agents of adaptive change. We discovered a larger than expected amount of genetic variation in these repeating sequences between the fly populations and saw that the variation resulted in potentially functional differences in important biological processes, such as stress resistance and mating."

Even with migration, cross-breeding, and near-extinction of whole populations, the environment is the driving force in the fruit-fly gene pool in Evolution Canyon.

The two slopes of the canyon are about two football fields apart at their bases—between 100 meters and 400 meters—but the south-facing slope is tropical and may receive eight times as much sun, while the north-facing slope is darker, more like a European forest.

Animals genetically adapt depending on whether they live on the drier, hotter side of the canyon, or the more humid, cooler side.

Researchers extracted DNA from flies collected in the canyon, then identified and mapped repeating patterns of what genomics researchers call "transposable elements"—DNA sequences capable of spontaneously changing position within the genome.

The scientists discovered flies taken from the opposing sides of the canyon displayed a significant difference in the contents and distribution of mobile elements.

The biological roles of these place-jumping, repetitive elements are mysterious.

They are largely viewed as "genomic parasites," but in this study, researchers found the mobile DNA can provide genetic novelties recruited as certain population-unique, functional enrichments that are nonrandom and purposeful.

"The first shocker was the sheer volume of due to the dynamics of mobile elements, including coding and regulatory genomic regions, and the second was amount of population-specific insertions of transposable DNA elements," Michalak said. "Roughly 50 percent of the insertions were population unique."

More than 65 percent of disease-causing genes in humans are believed to have functional counterparts in the fly, including many genes involved in certain cancers, Alzheimer's and Parkinson's diseases, heart disease, and other medical conditions.

The discovery adds to current understanding of the biodiversity and ability of a species to adapt to rapidly changing climates and other environmental conditions.

Explore further: Environment drives genetics in 'Evolution Canyon'

More information: Divergence of Drosophila melanogaster repeatomes in response to a sharp microclimate contrast in Evolution Canyon, Israel, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1410372111

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JVK
1 / 5 (4) Jul 08, 2014
"Roughly 50 percent of the insertions were population unique."

The insertions are nutrient-dependent and pheromone-controlled in all species, which means the insertions are not random, not linked to mutations, not naturally selected, and cannot automagically result in the unconstrained evolution of biodiversity.

Instead, it means that ecological variation results in ecological adaptations via conserved molecular mechanisms in species from microbes to man.

"Evolution canyon" is the place where animals "...have been able to adapt and survive in such close, but extremely different, ecologies."

It should be called "ecological adaptation canyon" so that social scientists are not confused about how ecological variation and ecological adaptation contribute to biodiversity, since mutations and natural selection do not contribute to the insertions.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model.
http://www.ncbi.n...24693353
JohnGee
5 / 5 (2) Jul 08, 2014
JVK is a fraud and a snakeoil salesman.
JVK
1 / 5 (1) Jul 09, 2014
JVK's award-winning publications:
Human pheromones: integrating neuroendocrinology and ethology
http://www.nel.ed...view.htm

The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences
http://www.sexarc...kohl.htm

The across-species genetic conservation of intercellular and extracellular chemical communication enables unicellular and multicellular organisms to functionally distinguish between self and non-self. Non-self olfactory/pheromonal input from the social environment elicits a vertebrate neuroendocrine response. The organization and activation of this neuroendocrine response modulates the concurrent maturation of the mammalian neuroendocrine system, the reproductive system, and the central nervous system during the development of sexual preferences that may be expressed in sexual behavior. Psycho-physiological mechanisms for the development of these sexual preferences include focus on unconscious affects...
Captain Stumpy
not rated yet Jul 09, 2014
The insertions are nutrient-dependent and pheromone-controlled in all species, which means the insertions are not random, not linked to mutations, not naturally selected, and cannot automagically result in the unconstrained evolution of biodiversity
@jk
IF it is TRUE that it cannot be linked to MUTATION, then your post here
Nutrient-dependent/pheromone-controlled adaptive evolution: a model
is a known fallacy and a blatant lie perpetrated to deceive. SO
since mutations and natural selection do not contribute
and YOUR MODEL causes MUTATIONS, per your own words
I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
(this is the DEFINITION of mutation) to which you answered
YES!--Thanks for asking
then you are LYING above, and because you ALREADY KNEW IT, then you are intentionally causing disruption and promoting PSEUDOSCIENCE

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