Some genes boost odds for distributing variety of traits, drive evolution

December 28th, 2009 - 5:01 pm ICT by ANI  

Washington, Dec 28 (ANI): Two Johns Hopkins scientists have said that genes that don’t themselves directly affect the inherited characteristics of an organism but leave them increasingly open to variation may be a significant driving force of evolution.

Their proposed amended view of evolution is based on observations of genetic patterns outside of a cell’s DNA and may better explain how organisms, including people, have adapted over hundreds of thousands of years to relatively rapidly changing environments.

The view also offers a new explanation for the genetic basis of some persistent, common human diseases.

“We’re proposing that certain gene variants contribute to heterogeneity in populations. In a fluctuating environment, this gives generations more opportunity to survive,” Science Daily quoted Dr. Andrew Feinberg as saying.

For over 100 years, science has been following Darwin’s view that characteristics that increase an organism’s ability to survive and reproduce will be passed from generation to generation.

Scientists later demonstrated that stable, significant traits are indeed inherited in the DNA carried in parental genes on chromosomes and randomly distributed to offspring.

Feinberg says some scientists have sought to explain gaps in Darwinian theory with epigenetics, the study of changes to genes that don’t directly affect the DNA sequence, but do affect which genes are turned on or off and therefore which proteins are produced in cells.

In the new study, researchers led by Dr. Rafael Irizarry, have suggested that gene variants or alleles able to take on the challenge and increase random distribution of characteristics might drive the development of the wide variety of traits — from height to skin tone to disease risk — seen in modern populations.

The scientists developed this idea through a series of experiments examining epigenetic patterns in groups of mice littermates that were very similar genetically.

The researchers suggest in the study that the presence of genes that contribute to trait variability might help explain the presence of common diseases.

Feinberg and Irizarry suggest that though it’s unclear how these variability genes acquire such inconsistent epigenetic changes, one mechanism may be environmental influence.

“The interaction between nature and nurture may be simpler than we’ve imagined,” said Irizarry.

The study is published in the early online edition of the Proceedings of the National Academy of Sciences. (ANI)

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