Blackwell Publishing

Molecular and Mendelian Genetics - What is selfish DNA?


The C-factor paradox

Selfish DNA is a possible solution to what biologists call the C-factor paradox: the apparent excess of DNA in the cells of some species.

If the excess DNA was selfish it would then have no use or function; it would be selectively neutral, and passively replicated from generation to generation. If the hypothesis is right, it would explain why this apparently functionless DNA actually is functionless.

It could also explain why the degree of excess DNA differs so much among species: the amount of repetitive DNA will fluctuate through time as it evolutionarily grows by mutation and drift (or selection) and shrinks when selection acts against excessive accumulations of repeats; different species would be the still-frames in a moving picture.

Currently the best explanation for the apparent excess of DNA in our cells is therefore that it is due to the passive accumulation of selfish DNA.

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