The the first team of researchers identified the genetic signature in the plant Arabidopsis thaliana
that governs the plant’s fitness in different climates -- cold or warm; wet or dry -- throughout its natural habitat, and found that climate is a major factor influencing the expression of this group of genes as it is passed on, optimizing the species' reproduction and survival, but the second team found other mechanisms that could limit genomic adaptability during periods of rapid climate change, Brown University News
reported about the teams' papers, both published
in the October 7 issue of the journal Science.
Johanna Schmitt, director of the Environmental Change Initiative at Brown and one of the authors on the first paper stated
, according to ScienceDaily:
“This is the first study to show evolutionary adaptation for Arabidopsis thaliana on a broad geographical scale and to link it to molecular underpinnings. Climate is the selective agent.”
The team on the first research project planted and tracked 75,000 Arabidopsis plants (a species favored by plant biologists for its small genome) in a mix of strains that originated across its climate range, at four sites representing diverse climates: Oulu, Finland for cold; Norwich, UK for oceanic; Halle, Germany for continental; and Valencia, Spain for warm. They studied local strains in each of the regions also, to identify so-called "home court advantages."
Then the team looked for variations in the Arabidopsis genome among plants from the different climes, doing an association study for fruiting and survival that included over 213,000 single-nucleotide polymorphisms (SNP
s) that are also called alleles
, or DNA sequences that vary by one of the four building-block molecules (Adenine
); according to the researchers, the SNPs point to genome areas where reproduction and survival may be emphasized and also show regional variations, an indication that climate shapes the distribution of favorable alleles.
The team found the SNPs that determine fitness in Arabidopsis did indeed vary, region by region, and learned that the alleles associated with high fitness within each site were locally abundant there as well, demonstrating the home court advantage at the molecular genomic level.
A further finding indicated that climate variables appeared to regulate the geographic distribution of SNPs associated with reproduction and survival; for example, certain fitness-associated SNP alleles that were commonly found in the warm region in Spain were rarely found in the cold region in Finland.
Schmitt concluded, “We found that the genetic basis of survival and reproduction is almost entirely different in different regions, which suggests that evolutionary adaptation to one climate may not always result in a tradeoff of poor performance in another climate. Thus, the Arabidopsis genome may contain evolutionary flexibility to respond to climate change.”
According to the researchers, identifying the group of genes linked to Arabidopsis’ adaptive response to climate changes may help scientists learn how climate might also re-engineer other plants' genetic profiles beneficially.
The second study pinpointed genetic loci
associated with climate change adaptations in Arabidopsis and discovered some possible limiting factors to the plant's genetic flexibility; genes involved in key processes such as energy metabolism and photosynthesis were often close to genes associated with climate adaptation, this team discovered.
They also found evidence these gene loci often evolve in selective sweeps, as series of new advantageous mutations spread gradually, a strategy that might break down during periods of rapid climate change.
Lead author Joy Bergelson, the chair of the University of Chicago's Ecology and Evolution department explained
, according to Brown University News:
“The contribution of selective sweeps suggests that there will be limits on the rate at which this plant can adapt to climate change."
On a lighter note, a plant biologist who did not participate in either of these two studies, composed and sang an ode to Arabidopsis thaliana, documented by this video.