Ferns are an old plant species, dinosaurs munched on them over 200 million years ago. If we want to know how to survive against nature's onslaught over the long haul, ferns are as good a place as any to start.

Even recent ones can show us how to evolve and outlast. A group of ferns evolved much more recently, and they did it while colonizing the extreme environment of the high Andes. Their completely new morphology (form and structure) arose and diversified within the last 2 million years. How this group of ferns grew in a unique ecosystem of the Andean mountains was the subject of a new study by Dr. Patricia Sanchez-Baracaldo and Dr. Gavin Thomas.

This ecosystem, known as the páramo, was created relatively recently (around 3 to 5 million years ago), when the Andes underwent a major uplifting event. This provided new ecological opportunities for plants to exploit and flourish in. Other plants from North America and temperate southern regions were also able to colonize these new páramo environments.

In contrast to the archetypal tropical rainforest, where trees are tall and some plants have huge leaves, the páramos are more exposed, tundra-like biomes where plants are short and have much smaller leaves, some of which are very hairy.

Higher altitudes near the equator experience extreme environmental fluctuations every twenty-four hours, with very cold nights and very hot days. In order to grow there, some plants have evolved new adaptations, in form and in leaf structure, which allow them to cope with the paramos' freezing nights and high solar radiation at midday.

The team found that one group of páramo ferns evolved highly modified leaves, which retain the furled fronds of a young fern yet are sexually mature. Some páramo species were found to have over 300 pairs of leaflets per frond – this is in contrast to their closest relatives in the more sheltered habitat of the cloud forest, lower down the mountains, which have no more than 12 pairs of leaflets per frond. In addition, the length of these leaflets declines rapidly with the increase in altitude.

The researchers also found that the rate by which new biological species arise (speciation) is significantly higher among páramo than non-páramo ferns.

Sanchez-Baracaldo, of the University of Bristol's School of Geographical Sciences, said, "These ferns are remarkable because, in geological terms, they quickly evolved a new morphology as a response to new and extreme environmental conditions. 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."