Reproducing early and often is the key to rapid evolution in plants
Yale researchers have harnessed the power of 21st century computing to confirm an idea first proposed in 1916 - that plants with rapid reproductive cycles evolve faster. Their findings appear in the October 3rd edition of Science.
"Our study has profound consequence for the understanding of evolution made possible by the critical role of the computer in revealing major evolutionary patterns," said senior author Michael Donoghue, the G. Evelyn Hutchinson Professor of Ecology & Evolutionary Biology and Curator of Botany at Yale's Peabody Museum of Natural History.
Long involved with the Tree of Life Web Project, which is attempting to reconstruct the "tree" representing the genealogical relationships of all species on Earth, Donoghue has spearheaded the study of flowering plant evolution. In animals, the variation in rate of molecular evolution has been ascribed to differences in generation time, metabolic rate, DNA repair, and body size; in plants, the differences have been more difficult to determine.
The current analysis evaluated DNA sequence data for five major evolutionary lineages within the flowering plants, comparing genetic markers in their chloroplast, nuclear, and mitochondrial genomes. The authors also employed new methods for making some of the largest phylogenetic trees ever built.
A clear pattern emerged. Plants with a shorter generation time - from the time they germinate to the time that a seed they produce germinates - generally show more rapid rates of molecular evolution. Longer-lived trees and shrubs, by contrast, evolve more slowly and show less variability in their rates of evolution. The study also showed that the difference in rate seen between herbs and woody plants has been maintained through evolutionary time.
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Researchers Catch Lake Victoria Fish in the Act of Evolving
In Africa's Lake Victoria, researchers believe they've caught a fish population in the act of splitting into two distinct species. Researchers say this example of evolution-in-action is remarkable because the two sub-populations of fish aren't geographically isolated and could theoretically interbreed, but adaptations to their vision are causing them to diverge.
Lead researcher Norihiro Okada and his colleagues had previously shown that cichlid fish in Lake Victoria's shallow waters are bathed in bluer light, while the turbid water of the lake predominantly lets redder light filter down to fish living in deeper water. The researchers showed that the fish's eyes have adapted to this difference so that fish that live in deeper water have a pigment in their eyes that is more sensitive to red light, while shallow-water fish have a pigment that's sensitive to blue [Science News]. Okada's new study, published in Nature [subscription required], shows that those eye adaptations have also affected mating patterns.
From Discover magazine.