Tuesday, September 8, 2009

Origin of Flowers

(Photo courtesy of Troy Carter)

Carl Zimmer wrote a great article for the NY Times about the evolutionary burst of flowering plants. It's way cool and an incredible reminder that few things in this world happen by mistake. Find it here. Here's the article's conclusion:

In the first flowers, the endosperm ended up with one set of genes from the male parent and another set from the female parent. But after early lineages like Amborella and water lilies branched off, flowers bulked up their endosperm with two sets of genes from the mother and one from the father.

Dr. Friedman, of the University of Colorado, Boulder, has documented the transition and does not think it was a coincidence that flowering plants underwent an evolutionary explosion after gaining an extra set of genes in their endosperm. It is possible, for example, that with extra genes, the endosperm could make more proteins.

“It’s like having a bigger engine,” Dr. Friedman said.

Other experts agree that the transition took place, but they are not sure it is the secret to flowers’ success. “I don’t know why it should be so great,” Dr. Doyle said.

As Dr. Friedman has studied how the extra set of genes evolved in flowers, he has once again been drawn to Goethe’s vision of simple sources and complex results.

Flowers with a single set of female DNA in their endosperm, like water lilies, start out with a single nucleus at one end of the embryo sac. It divides, and one nucleus moves to the middle of the sac to become part of the endosperm.

Later, a variation evolved. In a rose or a poppy, a single nucleus starts out at one end of the sac. But when the nucleus divides, one nucleus makes its way to the other end of the sac. The two nuclei each divide, and then one of the nuclei from each end of the sac moves to the middle.

Duplication, a simple process, led to greater complexity and a major change in flowers.

“Nature just doesn’t invent things out of whole cloth,” Dr. Friedman said. “It creates novelty in very simple ways. They’re not radical or mysterious. Goethe already had this figured out.”

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