When we talk about the 66-million-year-old asteroid, the scene immediately fills with craters, fire, dust in the atmosphere and wiped out dinosaurs. All very cinematic, of course. But underneath that catastrophe there were also more silent organisms, less suitable for posters in bedrooms, yet decisive for getting life back in motion: the flowering plants. Some, according to a new study published in Cellthey would have had a rather strange genetic mechanism on their side: the accidental duplication of the entire genome. A kind of extra copy of life’s instruction booklet, which appeared by chance and became useful just when the world was falling apart.
The study, signed by a research group also linked to the University of Ghent, analyzed the genomes of 470 species of angiospermsthat is, flowering plants, looking for traces of ancient duplications of the entire genetic heritage. The researchers then compared this data with information obtained from 44 plant fossilstrying to place the duplication events in time. The picture that has emerged is clear: many duplications that have survived over millions of years appear to be concentrated around major periods of environmental upheaval, including the mass extinction triggered by the asteroid that ended the era of the dinosaurs.
Double that helps
Most organisms have two sets of chromosomes, one inherited from each parent. In plants, however, something more eventful often happens: entire genomes can duplicate, creating organisms with additional sets of chromosomes. This phenomenon is called polyploidy. To clarify, many cultivated bananas have three sets of chromosomes, while wheat can have up to six. It seems like an oddity from a genetics textbook, but instead it also concerns what normally ends up on the plate.
The delicate point lies here: carrying a larger genome costs money. It requires more resources, can increase the risk of harmful mutations, and can create fertility problems. Under stable conditions, therefore, this duplication can become a disadvantage. When the environment changes abruptly, however, the same ballast can turn into margin for maneuver. More copies of genes also mean more possibilities to experiment, modify functions, withstand stress such as heat, drought or sudden collapses of ecosystems.
Simply put: in calm times those who consume little and remain efficient often win. In bad times, when the climate changes, habitats fail and old rules stop working, those who have more variability at their disposal can fare better. Nature, with the usual elegance of a messy warehouse, also preserves apparently uncomfortable pieces. Then disaster strikes and those pieces become tools.
Crises leave traces
Genome duplication observed in flowering plants appears to have a long history. According to the study, in the last few 150 million years they would have been there 132 independent events of whole-genome duplication, grouped in at least nine large waves. These waves coincide with heavy phases of Earth’s history: extinctions, global cooling, ecosystem collapses, periods of rapid warming.
Among these passages also appears the Paleocene-Eocene Thermal Maximumabout 56 million years ago, when global temperatures increased by approx 5-9 °C over about 100,000 years. For researchers, that period offers a useful comparison with the present, albeit with one huge difference: today, warming is happening much faster. Precisely for this reason polyploidy is studied carefully, because it could help some plants tolerate increasingly stressful conditions.
However, great caution is needed. This study tells of an evolutionary mechanism, reconstructed over very deep times, with millions of years ahead. Current climate change is on a much more brutal scale for ecosystems, agriculture and biodiversity. Genome duplication can offer an advantage to some species, under certain conditions, in long and complex processes. No plant gets a magic wand along with extra chromosomes.
The fascinating thing is precisely this: the flowering plants they would go through some of the worst crises in Earth’s history by exploiting a genetic accident. A copying error, apparently. A complication. A burden. Then the climate changes, the environment breaks down, the species best suited to the old conditions lose ground, and that flaw begins to resemble a possibility.
For us, who live in an era convinced that we can fix everything later, it is an uncomfortable lesson. Life has enormous resources, of course. It also has long times, cruel trials, gigantic losses. The plants that made it after the asteroid tell us about adaptation, resilience, randomness, selection. They also tell of everything that disappears before anyone can call it survival.
