Good news for fans of Jurassic Park, many people have a living being from the age of the dinosaurs in their living rooms this Christmas. This cheerfully sensationalist conclusion is my own, after reading a press release from L’Université Laval and the associated paper: A spruce gene map infers ancient plant genome reshuffling and subsequent slow evolution in the gymnosperm lineage leading to extant conifers.
The paper looks at the how the genome evolution differs for angiosperms, flowering plants, and gymnosperms. Conifers are good examples of gymnosperms, which don’t flower. The team writing the paper notes that angiosperms have had a lot of attention, but gymnosperms haven’t. Their research indicates something odd has happened to the conifer genome. Or maybe that should be something has oddly failed to happen to the conifer genome.
What they found was that ancient gene duplicates shared by angiosperms and gymnosperms outnumbered conifer-specific duplicates by a ratio of eight to one. Not only that but the ancient genes shared with angiosperms were much more shuffled round in the genome. It suggests that once conifers diverged from their relatives their genome settled down rapidly. The estimate is that the genome has been fairly stable for a hundred million years. That’s comfortably back into the Cretaceous period. “That doesn’t mean there haven’t been smaller scale modifications such as genetic mutations,” points out Prof. Jean Bousquet, who supervised the research. “However, the macrostructure of the conifer genome has been remarkably stable over the ages.”
It’s not a pattern you see with angiosperms and the difference has visible consequences. The press release notes that there are 600 known species of conifer and 400,000 species of angiosperm. “Conifers appear to have achieved a balance with their environment very early,” remarked Professor Bousquet. “Still today, without artifice, these plants thrive over much of the globe, particularly in cold climates. In contrast, flowering plants are under intense evolutionary pressure as they battle for survival and reproduction.”
It’s the lack of change that surprises me. When you think of all the changes that have happened around the trees over a hundred million years, gynmosperms must be staggeringly successful organisms.
You can read the full article as an Open Access paper.
Pavy N., Pelgas B., Laroche J., Rigault P., Isabel N. & Bousquet J. (2012). A spruce gene map infers ancient plant genome reshuffling and subsequent slow evolution in the gymnosperm lineage leading to extant conifers, BMC Biology, 10 (1) 84. DOI: 10.1186/1741–7007-10–84