Paper in press at Evolution: “Spatio‐temporal variation in fitness responses to contrasting environments in Arabidopsis thaliana”

Cross-posted press release

Exposito-Alonso et. al (2018) Evolution

Global climate change can have catastrophic consequences for many species, but a few might have the ability to survive or even thrive. Plants (and all organisms) have two options for responding to climate change: move to cooler environments (higher latitudes or altitudes), or stay and adapt to warmer temperatures. If a population stays, does it have the genetic variation needed to adapt, or does it have to wait for new mutations, thereby risking extinction in the meantime? This question was examined in a study published today in Evolution.

Biologists Moises Exposito-Alonso at the Max Planck Institute for Developmental Biology, Xavier Picó at the Doñana Biological Station, and collaborators tested the ability of the plant mustard cress (Arabidopsis thaliana) to adapt to hotter conditions using existing genetic variation. They found that offspring from some populations from the northwestern Iberian Peninsula performed well at two more southern, naturally warm sites. This suggests that for A. thaliana, and perhaps other plants, existing genetic variation can allow organisms to withstand new environmental conditions predicted by climate change projections.

The researchers planted 174,000 seeds of plants from the northwestern Iberian Peninsula in two locations in southern Spain, one at low altitude with higher temperature and higher precipitation, and one at high altitude with mild temperatures and low precipitation. In each of nine experiments, the researchers measured the proportion of seeds that sprouted, the time of flowering, and the number of seeds that each plant produced. They found that while many northern plants survived, those that came from warmer source locations flowered fastest, and as a result performed best overall.

“It is a global trend that plants are flowering earlier in spring as a response to climate change. Here we present evidence that flowering earlier has a fitness advantage, and that it has to do with the plants’ genetics,” said Exposito-Alonso.

In rainy years, however, this trend reversed—plants that flowered later were more successful. “This suggests that populations of genetically diverse plants might be favored in the long run if climate variability increases, and that responses to global warming are more complex than we thought,” added Exposito-Alonso.

These findings can help researchers better predict how species will respond to climate change. Genetic diversity within a species may be key in facilitating evolutionary adaptation to changing conditions. Knowing which genotypes do best in each environment can help inform conservation strategies such as assisted gene flow, where adapted seeds are imported to improve the local gene pool and help local populations adapt.

Mustard cress, Arabidopsis thaliana, genotypes flowering at different rates in the low altitude experiment. Credit: Moises Exposito-Alonso, Max Planck Institute for Developmental Biology.