Biological Sciences

“Fuel of evolution” more abundant than previously thought in wild animals

The raw material for evolution is much more abundant in wild animals than we previously believed, according to new research led by The Australian National University (ANU).

Stag from the Isle of Rum Deer Population

Darwinian evolution is the process by which natural selection results in genetic changes in traits that favour the survival and reproduction of individuals.

The rate at which evolution occurs depends crucially on genetic differences between individuals.

Led by Dr Timothée Bonnet from ANU, an international research team wanted to know how much of this “fuel of evolution” exists in wild animal populations.

The answer: two to four times more than previously thought. 

According to Dr Bonnet, the process of evolution that Darwin described was a slow one. 

"However, since Darwin, researchers have identified many examples of Darwinian evolution occurring in just a few years." Dr Bonnet said.

A common example of fast evolution is the peppered moth, which prior to the industrial revolution in the UK was predominantly white. 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 colour determined survival probability and was due to genetic differences, the populations in England quickly became dominated by black moths.

Dr Timothée BonnetThe Australian National University (ANU)

The study is the first time the potential for evolution has been systematically evaluated on a large scale, rather than on an ad hoc basis.

Studying Wild Animal Populations Around the World

The team of 40 researchers from 27 scientific institutions used studies of 19 populations of wild animals from around the world.

These included red deer on the Isle of Rum in the Inner Hebrides and Soay sheep, an ancient breed of sheep, on St Kilda, both in Scotland, and also great tits in Oxford.

Among the other wild animal populations studied around the world were meerkats in South Africa, spotted hyenas in Tanzania, song sparrows in Canada and collared flycatchers in Sweden. 

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 ran for an average of 30 years, providing the team with an incredible 2.6 million hours of field data. We combined this with genetic information on each animal studied to estimate the extent of genetic differences in their ability to reproduce, in each population.

Dr Timothée Bonnet

After three years of trawling through reams of data, Dr Bonnet and the team were able to quantify how much species change occurred due to genetic changes caused by natural selection.  

The method gives us a way to measure the current potential evolutionary change in response to natural selection across all traits in a population. Being able to see so much potential change came as a surprise to the team.

Dr Timothée Bonnet

Professor Loeske Kruuk, also from ANU and now based at the University of Edinburgh said:

This has been a remarkable team effort that was feasible because researchers from around the world were happy to share their data in a large collaboration. It also shows the value of long-term studies with detailed monitoring of animal life histories for helping us understand the process of evolution in the wild.

Professor Loeske KruukUniversity of Edinburgh

However, the researchers warn it’s too early to tell whether the actual rate of evolution is getting quicker over time. 

Whether species are adapting faster than before, we don't know, because we don't have a baseline. We just know that the current potential (the amount of 'fuel') is higher than expected from other less extensive studies, but not necessarily higher than before.

Dr Timothée Bonnet

Adapting to Environmental Change

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 discounted as a process which allows species to persist in response to environmental change. With global climate predicted to 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 more significant driver than we previously thought in the adaptability of populations to environmental changes.

Dr Timothée Bonnet

Related Links

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals, Science