Ferns Adapt to One of Earth's Most Extreme Environments

A group of Andean ferns, believed to be an "old" plant species dating back to the age of the dinosaurs, relatively recently adapted to one of the Earth's most extreme environments, a new study says.

The higher altitudes of the Andes Mountains comprise a unique ecosystem, known as the páramo, where there are very cold nights and very hot days. With such drastic fluctuations occurring every 24 hours, some plants had to learn to withstand the weather by evolving new adaptations. So plants like Andean ferns changed in form and in leaf structure, which allowed them to cope with the paramos' freezing nights and high solar radiation at midday. You will find that these plants are short and have much smaller leaves, some of which are very hairy.

And this novel morphology seemingly arose just within the last two million years.

"These ferns are remarkable because, in geological terms, they quickly evolved a new morphology as a response to new and extreme environmental conditions," researcher Dr. Patricia Sanchez-Baracaldo of the University of Bristol said in a press release.

Researchers found evidence of this adaptation in a group of páramo ferns that were sexually mature, and yet still maintained the furled fronds of a young fern. Some páramo species were found to have over 300 pairs of leaflets per frond, a stark contrast to cloud forest fronds living in the more sheltered habitat lower down in the mountains. This related species had no more than 12 pairs of leaflets per frond, and what's more, the length of these leaflets declined rapidly with the increase in altitude.

"It's fascinating to notice that, by a process known as convergent evolution, whereby similar features evolve independently in species of different lineages, cloud forest ferns arrived at the same 'solution' in response to the same environmental pressures," Sanchez-Baracaldo added.

The results were published in the journal PLOS ONE.