New research suggests that Darwinian evolution could be happening up to four times faster than previously thought, based on an analysis of genetic variation.
The more genetic differences there are in a species, the faster evolution can happen, as certain traits die off and stronger ones get established. The team behind this latest study calls it the “fuel of evolution”, and they looked at data on 19 different wild animal groups around the world.
That data analysis revealed this raw material for evolution is more abundant than earlier estimates, and as a result we may have to adjust our expectations for how quickly animals evolve – a pertinent question in our age of climate change.
“The method gives us a way to measure the potential speed of current evolution in response to natural selection across all traits in a population,” says evolutionary ecologist Timothée Bonnet, from the Australian National University.
“This is something we have not been able to do with previous methods, so being able to see so much potential change came as a surprise to the team.”
Among the wild animals studied were superb fairy-wrens (Malurus cyaneus) in Australia, spotted hyenas (Crocuta crocuta) in Tanzania, song sparrows (Melospiza melodia) in Canada, and red deer (Cervus elaphus) in Scotland. It’s the first time that the speed of evolution has been assessed on such a large scale.
The average length of each field study was an impressive 30 years, with details of births, deaths, mating and offspring all recorded. The shortest was 11 years and the longest a whopping 63 years. That gave the researchers a grand total of 2.6 million hours of field data to combine with genetic information on each animal.
It took three years, but the team eventually quantified how much species change had been caused by genetics and natural selection. Although Charles Darwin originally thought evolution was a very slow process, previous research has already shown that in some species, evolution can occur in just a few years.
“A common example of fast evolution is the peppered moth, which prior to the industrial revolution in the UK was predominantly white,” says Bonnet. “With pollution leaving black soot on trees and buildings, black moths had a survival advantage because it was harder for birds to spot them.”
“Because moth color determined survival probability and was due to genetic differences, the populations in England quickly became dominated by black moths.”
As there’s no baseline to work from – this is the first study of its type – the researchers emphasize there’s not yet enough evidence to show species are evolving faster than in the past. What is clear is that there’s more of this “fuel of evolution” than we thought.
With the world and its wildlife reeling from the ongoing effects of climate change, knowing more about how quickly animals can adapt will be helpful in modeling which species will be able to survive and which won’t.
The concern is that as shifts in the global climate continue to accelerate, species won’t be able to adapt in time. Even more comprehensive and longer term studies are going to be important to figure out exactly how quickly evolution is taking place.
“This research has shown us that evolution cannot be discounted as a process which allows species to persist in response to environmental change,” says Bonnet.
“What we can say is that evolution is a much more significant driver than we previously thought in the adaptability of populations to current environmental changes.”
The research has been published in Science.