Downsized Genome Helped Flowering Plants Conquer The World


Ever wondered how flowering plants have conquered essentially every part of the Earth in glorious diversity?

New research finds that the flowering plants had to go small in order to take on the world.

Darwin's 'Abominable Mystery'

In 1879, Charles Darwin wrote to his friend Joseph Hooker regarding what he described as an "abominable mystery," referring to the mystery surrounding the origins of flowering plants.

Since then, the term has been used to symbolize everything surrounding the origin and evolution of flowering plants.The subject has been a topic of interest for scientists for many years, including the very mechanisms that allowed flowering plants to spread all throughout the planet.

In recent years, it has been shown that a lot of flowering plants' success may be attributed to its excellent rates of photosynthesis, thanks to its specialized leaves. It is believed that it is because of this trait that flowering plants were able to fiercely compete with conifers and ferns.

The question now is how flowering plants were able to develop such specialized leaves that helped secure their success.

Downsizing For Domination

New research finds that in order to compete with the then-dominant conifers and ferns, flowering plants shrunk their genomes. In a search for answers, researchers Kevin Simonin of San Francisco State University and Adam Roddy of Yale University scoured the existing data and found a direct link between the plants' successful developments and the size of their genome.

What they found was an evident downsizing of genomes in hundreds of flowering plant species about 140 million years ago. It was around the same time when early flowering plants were beginning to spread and diversify all around the world.

The downsized genomes let the plant cells to be downsized as well, allowing more of the specialized cells, for instance, those responsible for photosynthesis, to be packed in greater variety in a given amount of space. Evidently, having smaller genomes in greater variety and number gave them the competitive edge they needed to spread all around the world compared to conifers and ferns.

"Flowering plants are the most important group of plants on Earth, and now we finally know why they've been so successful," said Kevin Simonin, coauthor of the study.

Natura Non-Facit Saltum

Is the mystery a mystery no longer? Researchers believe that there are still questions to be answered. For one, there is the question of how the flowers were able to downsize their genomes while other plant species did not, as well as how conifers and ferns managed to remain existing despite their larger genomes.

What's more, some scientists believe that the so-called "abominable mystery" may not have been specifically about Darwin's struggle with understanding angiosperm history, but about the notion of rapid evolution. This is exampled by what is currently happening with some species observed to be rapidly evolving as a result of variables like urban development and climate change. Such notion is believed to be quite a strong exception to Darwin's belief of "natura non facit saltum" or "nature does not make a leap."

Regardless of what Darwin perceived as the true abominable mystery, the current study does open up the door widely for understanding the history of angiosperms.

The study is published in PLoS Biology.

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