Teaching Evolution

A blog devoted to teaching evolution, both in our schools and in our communities.

Wednesday, March 23, 2005

A Plant Can Fix Its Flawed Gene

Scientists at Purdue University have discovered that plants that inherit a defective gene from both parents can also inherit a corrected version of the gene from some earlier generation of ancestors. As the New York Times reports,

The finding implies that some organisms may contain a cryptic backup copy of their genome that bypasses the usual mechanisms of heredity. If confirmed, it would represent an unprecedented exception to the laws of inheritance discovered by Gregor Mendel in the 19th century. Equally surprising, the cryptic genome appears not to be made of DNA, the standard hereditary material.

The discovery also raises interesting biological questions - including whether it gets in the way of evolution, which depends on mutations changing an organism rather than being put right by a backup system.

[snip]

The finding poses a puzzle for evolutionary theory because it corrects mutations, which evolution depends on as generators of novelty. Dr. Meyerowitz said he did not see this posing any problem for evolution because it seems to happen only rarely. "What keeps Darwinian evolution intact is that this only happens when there is something wrong," Dr. Surridge said.

The finding could undercut a leading theory of why sex is necessary. Some biologists say sex is needed to discard the mutations, almost all of them bad, that steadily accumulate on the genome. People inherit half of their genes from each parent, which allows the half left on the cutting room floor to carry away many bad mutations.


More on the Purdue University site here.

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