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The Incredible Shrinking Genome

Shipud (685171) writes | more than 5 years ago

Earth 2

Shipud (685171) writes "Mammalian genomes have been shrinking for about 65 million years, since the dinosaur extinction. Why? And why were mammalian genomes 3 times larger than they are today before the dinosaurs went extinct? A new article in Genome Biology and Evolution tries to explain this bizarre finding, and why the genomes of mammals (but not of other living groups) are still shrinking."
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Reduced Competition (1)

whrrr (1087271) | more than 5 years ago | (#28535613)

TFA states that the amount of foreign DNA (inserted by retroviruses, etc) in mammals has been decreasing since a few million years after the K-T extinction event. Seems to me that the enormous number of new niches opened up to mammals following the decline of the dinosaurs would have allowed species to thrive in spite of harmful foreign DNA manipulation. Then for the next 60 million years or so, the detrimental effects would slowly be pruned by natural selection.

Re:Reduced Competition (1)

Shipud (685171) | more than 5 years ago | (#28535951)

The problem is that in the original article, the authors speculate that genome size may have been 3 times as large as it is now, prior to the KT extinction. Why did pruning of mobile DNA elements as a fitness increaser apply then, when mammals were competing for teh few neiches left to them by the dinosaurs? Of course, the authors may be wrong in their speculation on pre-KT mammal genome size. If so, your own explanation sounds plausible.
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