Scientists may now be closer to being able to predict which species will be able to adapt to our warming world - and which won’t.
Climate change has already pushed many species to the brink, and wiped out others, due to problems such as habitat loss and temperature swings, the researchers say.
Using genome sequencing, researchers have found that fish such as the threespine stickleback, can adapt very rapidly to extreme seasonal changes.
Stickleback are known for their different shapes, sizes, and behaviours, and can even live in both seawater and freshwater, and under a wide range of temperatures.
Researchers found that stickleback genetically change to adapt to cold waters and warm summers.
Watch: No gas boilers to be sold by 2025 to reach net zero
Alan Garcia-Elfring, a doctoral candidate at McGill University said: "The modern version of Darwin's idea of evolution by natural selection posits that organisms with genes that favour survival and reproduction will tend to leave more offspring than their peers, causing the genes to increase in frequency over generations.
“As a result, populations become adapted or better-suited to their environments over time.”
"However, this process has typically been studied retrospectively, in populations that adapted to their current environments long in the past.
“This can make it difficult to understand the sequence of events - for example, which traits were most important and when - that led to their adaptation.”
To study natural selection in action, the researchers tracked six populations of threespine stickleback fish before and after seasonal changes to their environment, using genome sequencing.
Seasonal changes driven by wet winters and dry summers result in drastic shifts in habitat structure and balance of salt versus freshwater.
Only those fish able to tolerate these rapid changes survive into the next season.
Rowan Barrett, the Canada research chair of biodiversity science at McGill University said: "These changes probably resemble the habitat shifts experienced by stickleback populations when they colonized many newly created freshwater lakes from the ocean after the glaciers receded 10,000 years ago.
“We hope to gain insight into the genetic changes that may have resulted from natural selection long in the past."
Remarkably, the researchers discovered evidence of genetic changes driven by the seasonal shifts in habitat that mirrored the differences found between long-established freshwater and saltwater populations.
Garcia-Elfring said: "These genetic changes occurred in independent populations over a single season, highlighting just how quickly the effects of natural selection can be detected."
"The findings are important because they suggest that we may be able to use the genetic differences that evolved in the past as a way to predict how populations may adapt to environmental stressors like climate change in the future.”
Watch: How Systemic Racism Affects the Trees in Your Neighborhood