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Survival of the fittest? Study suggests it's more a game of chance 

In a world where “survival of the fittest” is seen as the absolute truth, a surprising study challenges this belief. Dr. James Saulsbury from the University of Kansas has uncovered secrets that change how we understand evolution.

The research shows a different story. It’s not just about adapting, but also about chance and luck playing a big role in who lives and who dies.

Red Queen hypothesis 

Think of the famous scene in Lewis Carroll’s “Through the Looking-Glass” where Alice runs as fast as she can yet stays in the same place. The Red Queen hypothesis in biology uses this imagery to explain how species evolve. 

It’s not just about becoming the strongest or fastest species, but about being the fittest by keeping up with everyone else.

The theory suggests that organisms aren’t simply competing for resources or outsmarting predators; they’re engaged in an ongoing race against evolving threats and challenges. 

Every adaptation, every shift in behavior, is a desperate attempt to stay in the same relative position.

Neutral theory of biodiversity 

By contrast, the neutral theory of biodiversity suggests that the “stroke of luck” plays a far bigger role than intense competition or adaptive superiority. 

The theory proposes that most species are functionally equivalent in their ability to survive and reproduce. Their abundance and distribution aren’t necessarily determined by being “better” or “worse,” but by the whims of random births, deaths, immigrations, and extinctions

Analysis of ancient animals

Dr. Saulsbury’s team delved into the rich fossil record of microscopic marine creatures known as zooplankton. This allowed them to track species’ lifespans over millions of years. 

By analyzing the fossil’s ages at the time they vanished, the researchers could compare them to other species.

Dr. Saulsbury’s aim was to see if extinction was more like a random lottery, as the “neutral theory” predicted, or a fierce competition where only the best adapted survived, as the Red Queen hypothesis suggests.

Chance and the struggle for survival 

Surprisingly, the researchers concluded that the forces shaping species’ fates might be a mix of chance and the basic struggle for survival in a world with limited resources.

In the past, people believed younger species were less likely to die out than older ones because they had more time to adapt

“Scientists kept finding instances where young species are especially at risk of extinction. So we had a theory vacuum – a bunch of anomalous observations and no unified way of understanding them,” explained Dr. Saulsbury.

The study suggests that younger species might actually be more likely to go extinct. This is because they haven’t had as much time to evolve and deal with changes in the environment. This finding supports the idea that all species have an equal chance of survival, regardless of their age.

More importantly, the findings aren’t a complete dethronement to the Red Queen hypothesis. The researchers still acknowledge the importance of continuous adaptation in some cases. 

“Red Queen theory has been a compelling and important idea in the evolutionary biological community, but the data from the fossil record no longer seems to support that theory,” said Dr. Saulsbury. 

“But I don’t think our paper really refutes this idea because, in fact, the Red Queen theory and the neutral theory are, in a deep way, pretty similar. They both present a picture of extinction happening as a result of competition between species for resources and of constant turnover in communities resulting from biological interactions.”

The study suggests that instead of a linear race, life thrives in a web of interconnectedness, driven by diverse forces like ​​cooperation, competition, and adaptation.

Nature is like a lottery 

The study supports the idea that nature is more like a lottery than a competition. The neutral theory of biodiversity, once considered strange, suggests that all living things, from the tiniest insect to the largest whale, have an equal chance of disappearing. It’s not about who’s “better,” but about random luck.

Dr. Saulsbury’s work gives new life to the idea that luck, not just being the strongest or most specialized, can help species survive. 

“What makes a species vulnerable to extinction? People are interested in learning from the fossil record whether it can tell us anything to help conserve species,” said Dr. Saulsbury.

‘The pessimistic side of our study is that there are ecological situations where there isn’t a whole lot of predictability in the fates of species; there’s some limit to how much we can predict extinction.” 

“To some extent, extinction will be decided by seemingly random forces – accidents of history. There’s some support for this in paleobiological studies.”

For instance, the extinction of dinosaurs, likely due to an asteroid impact, paved the way for mammals to take center stage. This wasn’t because mammals were inherently “better,” but because they just happened to be around when the dinosaurs were not.

Adaptability and versatility 

Another example is animals living on an island, cut off from the mainland. Fewer predators and competitors let them evolve in unique ways. This “luck” can lead to amazing adaptations, like the flightless birds of Galapagos or the giant lemurs of Madagascar. These were all created by chance events like volcanic eruptions, separating them from their mainland ancestors.

But being in the right place isn’t everything. Some species have another secret weapon: adaptability. These “generalists” aren’t picky about their environment. They can eat different foods, live in different places, and handle change better than specialists. Think of a raccoon, happy in a city trash can or a forest stream. This “versatility luck” helps them survive as the world around them shifts.

Study implications

The study explains that even weak or young species can survive if they have adequate resources. This means protecting forests, reefs, and other natural areas so animals have space and resources they need. 

Changes in the environment, like climate change and pollution, hurt young species the most. We need to slow down these changes to give all animals a better chance. This means reducing pollution, using energy wisely, and working together to protect the planet.

Raising public awareness and educating the public about the complexities of extinction and biodiversity loss is also essential. 

Using the study’s knowledge, the public and policymakers can better appreciate the need for comprehensive conservation strategies that address the challenges of preserving biodiversity.

The research is published in the journal Proceedings of the National Academy of Sciences.

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