Altitude drives evolution in species

It was an understudied factor. Yet it proved vital to understanding evolution. The rise and fall of the earth’s surface transforms nature. And it’s been like that for the last three million years. Altitude drives evolution in species. In particular, the evolution of birds and mammals. So says a study published in the journal ‘Nature Ecology and Evolution’.

Altitude drives evolution in species by isolating populations.
Altitude drives evolution in species, by isolating populations.
Unexpected variable

Researchers at Cambridge University in the UK got down to work. They looked at changes in the elevation of the Earth’s surface over the last three million years. They cross-referenced this with data on climate change over that time. Also, with the location of bird and mammal species. Their results reveal how species evolved into new ones. And it was as the elevation of the land changed.

The effect of rising elevation is greater than that of historical climate change. It has more influence on the origin of new species or ‘speciation’.

“On mountaintops there are many more unique species that are not found elsewhere. It used to be thought that the formation of new species was driven by climate. But elevation change has a larger effect on a global scale.” This is according to Dr Andrew Tanentzap of Cambridge University, lead author of the paper.

As the topography changed on Earth, new species emerged.
As the topography changed on Earth, new species arose.
Isolating populations

What happens as the elevation of the land increases? Temperature usually decreases and habitat complexity increases. As mountains form, the increase in elevation creates a barrier. And it prevents species from moving and mixing. Populations become reproductively isolated. This is the first step towards the formation of new species.

“It’s amazing how elevation influences global biodiversity. It is much more important than temperature, for example,” says Dr. Javier Igea. He works at the University of Cambridge, first author of the work.

If altitude drives evolution in species, this change will continue to occur. As long as the Earth continues to rise and fall, topography will continue to be an important driver of evolutionary change.

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