Ancient chaos may have favored genetically overloaded plants
Flowering plants dominate much of the modern world, from forests and grasslands to farms and gardens. A new evolutionary analysis suggests part of that success may trace back to a trait that is often a burden rather than a benefit: duplicated genomes. According to research summarized by New Scientist, accidental whole-genome duplication may have helped angiosperms survive some of Earth’s most disruptive environmental episodes, including the catastrophe linked to the extinction of non-avian dinosaurs.
The idea is counterintuitive. In many organisms, carrying extra copies of chromosomes can create serious problems. Growth can be impaired, reproduction can become more difficult, and long-term evolutionary survival is far from guaranteed. Yet in times of severe planetary stress, those liabilities may sometimes become assets.
What polyploidy means
Most sexually reproducing organisms carry two copies of each chromosome, one from each parent. Plants are different often enough to make that rule look flexible. Many can end up with more than two copies, a condition known as polyploidy. Potatoes and some varieties of wheat are familiar examples of plants with extra chromosome sets.
Among flowering plants, polyploidy is common in the present day. The source report notes that roughly a third of angiosperms alive now are polyploid. But the deeper history of the trait has been harder to interpret. Earlier analyses suggested that ancient genome duplications were relatively rare because many polyploid lineages eventually disappeared.
The new work asks a sharper question: if so many duplicate-genome lineages died out, why did some persist and spread?
A long evolutionary record
To investigate, researchers analyzed the genomes of 470 angiosperm species and used them to build an evolutionary tree spanning roughly 150 million years. Across that history, they identified and dated 132 ancient genome-duplication events. Those events were not evenly distributed through time. Instead, they clustered into nine prehistoric periods between about 108 million and 14 million years ago.
The striking finding is that almost all of those clusters coincided with major environmental or geological disruptions, including climate shifts, changing oxygen levels, and mass extinctions. One of the periods overlapped with the asteroid-impact era at the end of the Cretaceous, when the dinosaurs disappeared.
That pattern suggests genome duplication may have repeatedly become more valuable when the world turned unstable. In calmer periods, the trait may have been more costly than useful. In crisis periods, its evolutionary math may have changed.
Why extra genomes could help in bad times
The proposed mechanism is not that duplicated DNA is automatically advantageous. Most of the time, it can be harmful. But environmental upheaval changes selection pressures rapidly. When habitats transform, climates swing, and ecosystems collapse or reorganize, lineages with more raw genetic material may have more ways to adapt.
Extra copies of genes can create biological redundancy. That redundancy may provide room for evolutionary experimentation. One copy can continue performing an essential function while another is free to drift, mutate, or take on a modified role. Under stable conditions, that flexibility may not justify the costs. Under extreme stress, it can become a route to survival.
The concept fits a broader view of evolution as contingent rather than uniformly progressive. Traits that are wasteful in one era may become decisive in another. Polyploidy appears to be one of those traits. It may reduce fitness in ordinary times but turn into a reserve of adaptability when conditions become chaotic.
Why angiosperms matter
Flowering plants are not a niche curiosity. They form the basis of terrestrial ecosystems and human agriculture. Understanding how they survived earlier planetary shocks matters not only for reconstructing prehistory but also for thinking about resilience in the face of modern environmental change.
The research does not imply that plants can easily weather any disruption. It does, however, suggest that some of the flexibility visible in modern angiosperms may have been forged in repeated encounters with catastrophe. Today’s abundance may partly reflect survival filters imposed tens of millions of years ago.
That also helps explain a long-standing evolutionary puzzle. If polyploidy is so often costly, why is it still so widespread in flowering plants? The answer may be that rare but severe global crises repeatedly reset the ledger in its favor.
A reminder about survival and chance
The study’s findings are historical and statistical, not a direct replay of ancient ecosystems. Correlation with periods of upheaval does not prove the exact biological pathway for every lineage. Some duplicated genomes still vanished, and many non-polyploid plants survived too. Evolution rarely offers single-cause explanations.
Still, the pattern is powerful. It suggests that major environmental disruption did not merely eliminate species; it may also have selected for forms of hidden flexibility that looked inefficient beforehand. In that sense, flowering plants may owe part of their modern dominance to accidents of reproduction that became unexpectedly useful when the planet was under stress.
It is a compelling revision to a familiar story. Mass extinctions are often framed only in terms of loss. This research points to the traits that may have made survival possible for some of the lineages that followed. In the case of angiosperms, carrying extra genomes may have been one of the quiet advantages that allowed them to come through repeated planetary crises and ultimately reshape the living world.
This article is based on reporting by New Scientist. Read the original article.
Originally published on newscientist.com
