Irvine, Calif. -- Countering Charles Darwin's view that evolution occurs gradually, UC Irvine scientists have discovered that plants with short life cycles can evolutionally adapt in just a few years to climate change.
This finding suggests that quick-growing plants such as weeds may cope better with global warming than slower-growing plants such as Redwood trees -- a phenomenon that could lead to future changes in the Earth's plant life.
"Some species evolve fast enough to keep up with environmental change," said Arthur Weis, professor of ecology and evolutionary biology. "Global warming may increase the pace of this change so that certain species may have difficulty keeping up. Plants with longer life cycles will have fewer generations over which to evolve."
The study appears the week of Jan. 8 in the Proceedings of the National Academy of Sciences.
Weis and researchers Steven Franks and Sheina Sim studied field mustard, a weedy plant found throughout the Northern Hemisphere. In a greenhouse, they grew mustard plants at the same time from seeds collected near the UCI campus in the spring of 1997 -- two years before a five-year drought -- and seeds collected after the drought in the winter of 2004. Seeds can remain dormant but alive for years and be revived with a little water and light. The plants were divided into three groups, each receiving different amounts of water mimicking precipitation patterns ranging from drought to very wet conditions. In all cases, the post-drought generation flowered earlier, regardless of the watering scheme.
This shift in genetic timing was further confirmed with an experiment that crossed the ancestors and descendents. As predicted, the intergenerational hybrids had an intermediate flowering time.
"Early winter rainfall did not change much during the drought, but the late winters and springs were unusually dry. This precipitation pattern put a selective pressure on plants to
Contact: Jennifer Fitzenberger
University of California - Irvine