California Drought Caused Plants To Evolve In Just Seven Years

We usually think of evolution as a long, laborious process, stretching over hundreds if not thousands of years. But sometimes, it happens much more quickly. In a paper published today in Molecular Ecology researchers announced that they found genetic differences between the ancestors and descendants of two separate populations of field mustard both of which evolved during the California drought between 1997 and 2004 to flowers earlier.

Back in 2007, Steven Franks, a biologist at Fordham University, published a paper that showed that field mustard plants grown with seeds collected in 1997, before the drought began flowered later than plants grown with seeds gathered in 2004, after the drought. He looked at two geographically isolated populations of field mustard, located about 1.9 miles apart in California. Flowering earlier lets a plant go to seed while the rainy season is still going on, giving its seeds a better chance of surviving in the future.

The process of looking at the evolution of organisms by comparing past and present populations is known as a resurrection experiment, and generally involves planting a saved sample of an earlier generation next to a sample taken from a later generation and growing them under the exact same circumstances to see what the differences between the two are.

The current study pushed those results further and looked at the genetics of the plants, and found that while both populations evolved to flower earlier, they each arrived at the same conclusion on a different genetic path. They found that of the genes that shifted in each population, only 0.025 percent were the same between the populations.

Franks and his team hope that by combining resurrection experiments with genetic analysis these results can help researchers gain a better understanding of how species can adapt to dramatic shifts like climate change or habitat loss.

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