Plants that are not able to rapidly adapt to climate change may decline and disappear from their previous habitats, prompting dramatic projects such as a doomsday vault for seeds of the world. Now researchers suggest find that seeds banked only for a few decades already do not do as well as one might expect when reintroduced into their original lands. This suggests environmental conditions have already shifted rapidly, according to findings detailed in the Proceedings of the National Academy of Sciences.
Adaptational lag is the idea that organisms that cannot adapt quickly enough to keep up with rapid environmental changes may decline or go extinct. Such adaptational lag is predicted to happen with climate change, but evidence of this is scarce.
To look for signs of this adaptational lag, evolutionary ecologist Johanna Schmitt at the University of California at Davis and her colleagues investigated a weedy relative of mustard, Arabidopsis thaliana, the first plant to get its genome sequenced. In experiments in gardens, they grew Arabidopsis from banked seeds in four sites across the native European range of the species — Valencia, Spain; Norwich, England; Halle, Germany; and Oulu, Finland.
As expected, seeds that originated from locales near the planting sites each proved relatively fit at those sites. However, seeds that originated from locales historically warmer than the planting sites unexpectedly proved even fitter than natives at every site, especially at the northern limit of Arabidopsis’s range in Finland. “We were surprised to find that southern immigrants did better than natives,” Schmitt says.
These findings suggest that because of climate change, banked seeds of this plant from historically warmer climates already outperform native populations of this plant. “The goal of seed banks is to preserve as much genetic variation as possible, and these findings suggest they should think about preserving the entire climatic diversity contained in a species, and use the seeds most appropriate to new climate conditions when restoring populations of a plant,” Schmitt says.