Dr. Mark Beilstein, a Mercer Postdoctoral Fellow in the Mathews lab of Arnold Arboretum, was very excited to discover previously overlooked fossil evidence that bears on the age of Arabidopsis thaliana, the foremost genetic model in plant biology. Prior estimates have been widely cited (more than 400 times) in a broad range of journals including Nature, Science, PLOS Genetics, Genome Research, PNAS, Nucleic Acids Research, Genetics, and many more. Beilstein and colleagues estimate ages for Arabidopsis and other splits in Brassicaceae to be two- to three-fold older than the published estimates, suggesting that the pace of gene, genome, and developmental evolution occurred more slowly than has been appreciated, and that Arabidopsis evolved in a period of significant warming rather than in a period of cooling. Although Arabidopsis is a weedy herbaceous plant, it is the experimental system in which basic plant processes, including those of woody plants, are being studied.
Well-preserved fossils of flowering plants that can be placed reliably in extant families are rare, hindering estimation of divergence times. A fresh and more detailed look at an ignored fossil, Thlaspi primaevum, allowed for the use of a fossil calibration point within the plant family Brassicaceae, which has a significant impact on divergence estimates. And given the importance of Arabidopsis, the revised estimates will impact multiple disciplines, including comparative genomics, evolution of development, and coevolution of animals and plants.