The biological factors leading to evolution are more abundant than previously thought in wild animals

A wader goes into the water of the “Vieux-Salins” in Hyères, in the southeast of France, on August 31, 2021.

A stilt rider walks through the water in

©Nicolas TUCAT / AFP


According to a study by an international research team, in the face of a rapidly changing world due to climate change, animals are able to evolve and adapt two to four times faster than previously thought.

Atlantico: We use the term “fuel for evolution”, what does this term cover?

Celine Teplitsky: It is an image that we use to denote genetic variance. For evolution to take place in a population, three things are required. Grades are needed that vary between individuals; that these variations have a genetic basis and therefore can be passed on to subsequent generations. Genetic variation is the part of variation in characters between individuals that is due to variation at the genetic level (as opposed to, for example, variation due to the environment). And finally, it is necessary that these characters are selected, that is, that they affect the condition (selective value), the number of descendants a person will leave for the next generation. Genetic variance is a description of populations’ ability to develop at time T in a given environment.

In your study, you ask whether animals, faced with a world that is changing rapidly due to climate change, are able to evolve and adapt. You conclude that both birds and mammals can develop two to four times faster than previously thought. How did you measure it? And how do you explain that?

Evolution can only happen if there is genetic variation. In our study, we looked at genetic variation in fitness, which estimates the overall evolutionary potential of a population. What we observe is that the genetic variation between individuals for fitness is greater than we thought. One of the explanations is very statistical. Our models represent this data better than before. Before the models used a Gaussian distribution, we now take into account that many individuals do not leave descendants (zero inflation). Our study covers 19 populations of 14 species, which equates to 2.6 million hours of fieldwork. This type of study is only possible based on long-term follow-ups and with pedigrees. These data make it possible to estimate how the variation is distributed between families and to estimate genetic variation without knowing which gene does what.

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Do these results provide information on whether animals are able to adapt to a changing world, especially due to the climate?

It’s a complicated question. Our study shows a significant genetic variation in fitness and suggests that fitness may increase by 10% per. generation. The population is therefore expected to increase. But that is not what we are observing. Several explanations can be put forward. Perhaps in the face of a changing world, their ability to evolve simply allows them to stay afloat. It is difficult to know for how long: the degradation of environments can have demographic effects much stronger than individuals’ ability to adapt. It is also possible that because everyone develops a little, it creates more competition. When everyone is running around you, you have to run to stay seated.

It was long believed that evolution was a very slow process. Our results emphasize that current developments can often be faster than previously thought, but it is difficult to extrapolate to the future, especially in a changing world – if only because genetic variation may depend on the environment. We must therefore remain cautious, but one thing is for sure, it is important to take into account the evolutionary capacities (and their limits) in order to understand and predict the future of the peoples.

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