Andean hummingbirds take different evolutionary paths to high altitudes

JULY 1, 2019

by Casey Mcgrath, Society for Molecular Biology and Evolution

Scientists have found that multiple hummingbird species have adapted to life at high altitudes in the Andes through distinct genetic mutations that nonetheless affect the same biochemical pathways. This suggests that while the details of molecular adaptation may differ at the amino acid and protein levels, there is predictability in evolution at the level of biochemical pathways.

The transition from living at low elevations to high elevations, such as those found in the Andes, Himalayas, and Tibetan Plateau, comes with many challenges. Extremely high elevations are associated with colder temperatures, increased exposure to ultraviolet radiation, and a lack of oxygen, which is 40% less abundant above 4,000 m than at sea level. Organisms that live at these elevations have developed specific adaptations that allow them to cope with these difficulties. For example, genetic analyses of humans living in the Andes and on the Tibetan Plateau have revealed changes in specific genes that enable them to deal with limited oxygen environments. However, it remains unclear whether such changes are generally predictable across different species or populations, or whether there is some flexibility in what changes occur. In a new article in Genome Biology and Evolution (Lim et al. 2019), a group of researchers from Stony Brook University, the University of New Mexico, and the Swiss Federal Research Institute set out to answer this question.

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High altitudes hamper hummingbirds' ability to maneuver

Date: December 8, 2016

Source: University of Faculty of Science British Columbia

 
Hummingbirds' ability to accelerate and turn diminishes at high altitudes, but it isn't a lack of oxygen to the body that limits the birds' performance -- it's physics.

"It appears the mechanics of high-altitude flight slow down the birds well before their respiratory system has an issue handling the lower-oxygen environment," said zoologist Paolo Segre, author of a new study in Current Biology.

"Just like a helicopter's rotors lose 'traction' at high altitudes with low air densities, the hummingbirds' wings don't perform as well."

Segre and colleagues at the University of British Columbia captured male adult hummingbirds and transported them to the White Mountain Research Centre in California. The centre, situated at 3,800 metres (12,500 feet), allowed the researchers to evaluate the birds' ability to accelerate and turn, and compare them to baselines gathered closer to sea level.

"Hummingbirds' acceleration, rotation and turning skills are key to their ability to compete for food and defend territory," said UBC zoologist Douglas Altshuler, senior author on the paper.

"As climate change continues to increase temperatures around the globe, more and more species will be forced to seek out cooler regions, including at higher elevations."

The elevation of 3,800 metres (12,500 feet) put the birds just beyond the species' maximum range in terms of elevation, but this was enough to dramatically lower the birds' aerial performance.

 

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