Genes can tell which animals will survive climate change
Using genome sequencing, the researchers have shown that some fish, like the Threespine Stickleback, can adapt very quickly to extreme seasonal changes.
Their findings could help scientists predict the evolutionary future of these populations.
Climate change is exacerbating problems such as habitat loss and temperature fluctuations that have already pushed many animal species to the brink. But can scientists predict which animals will be able to adapt and survive?
A popular subject of study among evolutionary ecologists, the stickleback is known for its various shapes, sizes, and behaviors – it can even live in both saltwater and freshwater, and under a wide range of temperatures.
But what is it that makes this species so resilient?
Identifying the genetic basis of adaptations, for example, to freshwater or in response to climate change, can be difficult.
“The modern version of Darwin’s idea of evolution by natural selection postulates that organisms whose genes promote survival and reproduction will tend to leave more offspring than their peers, which will lead to an increase in the frequency of genes over generations. As a result, populations adapt or become better adapted to their environment over time, ”explains lead author Alan Garcia-Elfring, doctoral student under the supervision of Rowan Barrett, chair of biodiversity science at the ‘McGill University.
“However, this process has generally been studied retrospectively, in populations that have adapted to their current environment for a long time. 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, ”he adds.
To study natural selection in action, the researchers followed six populations of Threespine Sticklebacks before and after seasonal changes in their environment, using genome sequencing. Sticklebacks found in various estuaries along the California coast provide a rare opportunity to study natural selection in real time. The seasonal changes brought about by wet winters and dry summers lead to drastic changes in habitat structure and the balance between salt and freshwater, and only fish that can tolerate these rapid changes survive until the following season.
Estuaries are periodically isolated from the ocean due to the formation of sandbanks during the dry summer months. “These changes probably resemble the changes in habitat experienced by stickleback populations when they colonized many newly created freshwater lakes in the ocean after the glaciers retreated 10,000 years ago,” says Barrett. . “We hope to gain insight into the genetic changes that may have resulted from natural selection for a long time.”
Remarkably, the researchers found evidence of genetic changes caused by seasonal changes in habitat that reflected the differences found between long-established freshwater and saltwater populations.
“These genetic changes have occurred in independent populations within a single season, highlighting how quickly the effects of natural selection can be detected,” Garcia-Elfring explains.
“The results are important because they suggest that we may be able to use genetic differences that have evolved in the past as a way to predict how populations may adapt to environmental stressors like climate change to future, ”he said.
The research highlights the importance of studying species in dynamic environments, such as estuaries built into bars, to better understand how natural selection works. In further research, they plan to study the degree of repeatability of the observed genetic changes, testing whether they occur year after year. This would demonstrate their ability to reliably predict the evolutionary future of these populations.
The study appears in Molecular ecology.
Source: McGill University