Scientists have found an explanation for how flowering plants became dominant so rapidly in ecosystems across the world — a problem that Charles Darwin called an ‘abominable mystery’. In a study publishing on January 11 in the open access journal PLOS Biology, Kevin Simonin and Adam Roddy, from San Francisco State University and Yale University respectively, found that flowering plants have small cells relative to other major plant groups and that this small cell size is made possible by a greatly reduced genome size.
This new research provides a mechanism. By scouring the literature for data, the authors argue that these anatomical innovations are directly linked to the size of their genome.
Because each cell has to contain a copy of the plant’s genome, smaller genomes allow cells to be smaller, and if cells are smaller then more cells (such as those specialized for photosynthetic metabolism and water and nutrient transport) can be packed into a given volume of space. Additionally, by shrinking the size of each cell, water and nutrient delivery can be made more efficient.
Comparing hundreds of species, the researchers found that genome downsizing began about 140 million years ago and coincided with the spread of the earliest flowering plants around the world. “The flowering plants are the most important group of plants on earth, and now we finally know why they have been so successful,” they say.
Although this research answers a major question, it opens the door to many more. Why were the flowering plants able to shrink their genomes more than other plant groups? What innovations in genome structure and packing have the flowering plants exploited? How have the ferns and conifers managed to elude extinction despite their large genomes and cells? Paper. (public access) – Kevin A. Simonin, Adam B. Roddy. Genome downsizing, physiological novelty, and the global dominance of flowering plants. PLOS Biology, 2018; 16 (1): e2003706 DOI: 10.1371/journal.pbio.2003706 More.
Opens the door to many more questions? For sure. “Why were the flowering plants able to shrink their genomes more than other plant groups?” One question is, how did they do that without loss of needed information? Did it happen quickly or slowly? Is there a pattern?
“How have the ferns and conifers managed to elude extinction despite their large genomes and cells?” But were they ever in danger of extinction on that account? Is there a general pattern by which life forms can be shown to be in danger on that account?