DNA Divergence

DNA Divergence

Subject: Science & technology

Context: Nobel laureate Svante Paabo and his team have just published one of the biggest genetic studies yet of Neanderthals, providing clues about their community life and structure.

Concept :

• Fresh from his award a couple of weeks ago of a Nobel prize for his work on the DNA of early human species, including Neanderthals, Svante Paabo have just published in Nature one of the biggest genetic studies yet of that species.
• These Neanderthals lived 50,000 years ago in the Altai mountains of Russia. The remains under study—17 bone and tooth samples belonging to 13 individuals—came from two caves about 100km apart.
• It is extremely unlikely that all of these individuals were contemporaries. But the researchers think they have found both a trio and a pair of relatives. They did this by computing a value called DNA or Genetic divergence.

DNA Divergence

• Genetic/DNA divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often leading to reproductive isolation and continued mutation even after the populations have become reproductively isolated for some period of time, as there isn’t genetic exchange anymore.
• In some cases, subpopulations living in ecologically distinct peripheral environments can exhibit genetic divergence from the remainder of a population, especially where the range of a population is very large.
• The genetic differences among divergent populations can involve silent mutations (that have no effect on the phenotype) or give rise to significant morphological and/or physiological changes.
• Genetic divergence will always accompany reproductive isolation, either due to novel adaptations via selection and/or due to genetic drift.
• It is the principal mechanism underlying speciation(occurs when a group within a species separates from other members of its species and develops its own unique characteristics).

Reproductive Isolation

• The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and physiological processes critical for speciation.
• They prevent members of different species from producing offspring, or ensure that any offspring are sterile.
• These barriers maintain the integrity of a species by reducing gene flow between related species