“Fuel of Evolution” – Raw material for evolution more abundant than expected in wild animals
Evolutionary raw material is far more abundant in wild animals than previously thought, new research shows Australian National University (UNA).
Darwinian evolution is the process by which natural selection results in genetic changes in traits that favor the survival and reproduction of individuals. The rate at which evolution occurs depends crucially on genetic variation between individuals.
An international research team, led by Dr Timothée Bonnet of the ANU, wanted to know to what extent this genetic difference, or “evolutionary fuel”, exists in populations of wild animals. The answer: two to four times more than previously thought.
“Being able to see so many potential changes was a surprise for the team.” — Dr Timothy Bonnet
According to Dr. Bonnet, the process of evolution described by Darwin was incredibly slow.
“However, since Darwin, researchers have identified many examples of Darwinian evolution occurring in just a few years,” Dr Bonnet said.
“A common example of rapid evolution is the peppercorn moth, which before the Industrial Revolution in the UK was predominantly white. With pollution leaving black soot on trees and buildings, black moths had a survival advantage as they was harder for birds to spot.
“Because the color of butterflies determined the probability of survival and was due to genetic differences, populations in England quickly became dominated by black butterflies.”
This is the first time that the rate of evolution has been systematically evaluated on a large scale, rather than on a scale ad hoc base. The team of 40 researchers from 27 scientific institutions used studies of 19 wild animal populations from around the world. These included superb wrens in Australia, spotted hyenas in Tanzania, song sparrows in Canada and red deer in Scotland.
“We needed to know when each individual was born, who they mated with, how many offspring they had and when they died. Each of these studies lasted an average of 30 years, providing the team with an incredible 2.6 million hours of field data,” said Dr. Bonnet.
“We combined this with genetic information about each animal studied to estimate the extent of genetic differences in their ability to reproduce, in each population.”
“This research has shown us that evolution cannot be thought of as a process that allows species to persist in response to environmental change.” — Dr Timothy Bonnet
After three years of research into tons of data, Dr. Bonnet and the team were able to quantify the magnitude of species shifts due to genetic changes caused by natural selection.
“The method gives us a way to measure the potential speed of current evolution in response to natural selection on all traits in a population. This is something we haven’t been able to do with previous methods, so being able to see so many potential changes was a surprise to the team,” Dr. Bonnet said.
Professor Loeske Kruuk, also from ANU and now based at the University of Edinburgh in the UK, said: ‘It was a remarkable team effort which was achievable because researchers around the world were happy to share their data in a great collaboration.
“It also shows the value of long-term studies with detailed tracking of animal life histories to help us understand the process of evolution in nature.”
However, the researchers warn that it is too early to tell whether the actual rate of evolution is accelerating over time.
“We don’t know if species are adapting faster than before, because we don’t have a benchmark. We just know that the recent potential, the amount of ‘fuel’, has been higher than expected, but not necessarily higher than before,” Dr Bonnet said.
According to the researchers, their findings also have implications for predictions of species adaptability to environmental change.
“This research has shown us that evolution cannot be ignored as a process that allows species to persist in response to environmental change,” Dr Bonnet said.
Dr Bonnet said that with a predicted increase in climate change at an increasing rate, there is no guarantee that these populations will be able to keep up.
“But what we can say is that evolution is a much bigger driver than we previously thought in the adaptability of populations to current environmental changes,” he said.
Reference: “Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals” May 26, 2022, Science.