Two species of marine snails, Littorina saxatilis, adapted to different environments. The crab ecotype (left) is larger and wary of predators. The wave ecotype (right) is smaller and has a bold behavior. © David Carmelite
Klosterneuburg, Austria — Typically, scientists believe that it takes countless centuries for evolution to bring about major changes in any species. However, a new study has seen this amazing process unfold in the blink of an eye.
A team of researchers from the Institute of Science and Technology of Austria (ISTA) and Norway's Nord University observed that sea snails evolve to closely resemble their ancestors over just 30 years – a fraction of the time in evolutionary terms.
The story begins in 1988 when a toxic algal bloom wiped out populations of sea snails from small rocky outcrops, known as skerries, on the Köster Archipelago near the Swedish-Norwegian border. While this environmental disaster may seem insignificant to many, for marine ecologist Kirsten Johansson of the University of Gothenburg, it presented a unique opportunity to study evolution in action.
Four years after the algae bloom, in 1992, Johansson decided to reintroduce the snails to one of these now empty pastures. And here's the twist: Instead of bringing back the same type of snails that lived there before, they introduced a completely different group of the same type, Litorina saxatilis.
These sea snails, commonly found along the shores of the North Atlantic Ocean, have evolved different traits to suit their specific environments. The two main species are known as “wave snails” and “crab snails.” Wave snailsOriginally inhabiting rocky rocks, they were small with thin shells, large, rounded vents, and a bold behavior—adaptations that helped them survive in wave-battered environments. Crab snailsOn the other hand, they are larger, have thicker shells, smaller openings, and a more wary behavior—traits that protect them from crab predators in calmer waters.
Johansson's experiment involved introducing crab snails to a ski area that was previously home to wave snails. The question was: How could these crab snails adapt to their new wave-exposed environment?
The results were published in the journal Advancement of science It was nothing short of amazing. Within just a few generations—the snails reproduce once or twice a year—scientists began to see evidence of adaptation. Over the course of 30 years, the cultured crab snails evolved to resemble the wave snails that inhabited the rock before the algae blooms.
“Over the course of 30 years of experimentation, we have been able to strongly predict what the snails will look like and which genetic regions will be involved. The transformation has been rapid and dramatic,” says Diego Garcia Castillo, an ISTA graduate student and one of the lead authors of the study. Media release.
What makes this study particularly fascinating is that the snails did not develop these new traits from scratch. Instead, they took advantage of genetic diversity that was already present in their population, albeit at low levels. This existing genetic diversity, combined with potential gene flow from neighboring wave snail populations, allowed rapid adaptation to the new environment.
The implications of this study extend beyond the world of snails. In an era of rapid environmental change, understanding how species adapt quickly is crucial.
“This work allows us to take a closer look at recurrent evolution and predict how a population might be able to develop traits that evolved separately in the past under similar conditions,” Garcia-Castillo explains.
Anya-Marie Westram, a researcher at Nord University and co-author of the study, emphasizes the importance of genetic diversity in adaptation.
“Not all species have access to large gene pools, and developing new traits from scratch is very slow. Adaptation is very complex, and our planet is also facing complex changes with periods of extreme weather events, rapid climate change, and pollution,” says Westram. And new parasites.” “This research may help convince people to protect a range of natural habitats so that species do not lose their genetic diversity.”
As our planet faces complex changes, including extreme weather events, climate change, pollution, and new parasites, the ability of species to adapt quickly could be key to their survival. This study provides a glimpse into how evolution works on relatively short timescales, offering hope for species facing rapid environmental change.
Today, the number of snails found on the experimental slopes has increased to about 1,000, demonstrating their remarkable ability to adapt and thrive in new conditions. As we continue to face environmental challenges on a global scale, lessons learned from these tiny marine snails could be invaluable in understanding and perhaps predicting how species will respond to our changing world.
Paper summary
methodology
In this study, the researchers wanted to know if they could predict how a group of sea snails would form. Litorina saxatiliswill adapt to the new environment. To do this, they moved the snails from a habitat dominated by crab predators to a place where strong waves shape the environment. This happened on the Swedish coast, where a small rocky island served as the testing site. The snails were observed over 30 years to track how their physical traits (such as shell size and shape) and genetic makeup changed.
The study focused on whether changes in shell traits and genes would match what researchers have already observed in snails that have naturally adapted to different environments elsewhere. They predicted changes in physical traits, the frequency of specific genetic traits, and chromosomal arrangements over time.
Key findings
The researchers saw dramatic changes in the snails that were transplanted into wave-dominated habitats. Over time, the snails began to look more like local residents that evolved naturally in wave-heavy environments. For example, their shells have become thinner, with different shapes and patterns compared to the thicker, more protective shells of snails found in the crab's habitat.
Genetically, many of the changes predicted by the researchers also came true. Genes associated with survival in a surf-heavy environment are becoming more common. Overall, the snails adapted quickly, and within just a few years, they looked and behaved more like snails adapting to the waves.
Limitations of the study
First, the study was conducted in a very specific environment, which means the results may not apply to all types of environmental changes. Waves and crabs represent only one set of natural stresses, and other factors such as temperature changes or pollution can affect snails differently.
The study also focused on a specific type of snail and may not apply to other organisms. Finally, because the researchers had to rely on occasional sampling over 30 years, there may have been gaps in the data that did not capture all the finer details of how the snails were changing.
Discussion and takeaways
The main idea of this study is that we can predict how populations will adapt to environmental changes based on what we know about their genetic diversity and how they have adapted elsewhere. The snails in this experiment adapted quickly, showing that species with existing genetic diversity can survive rapid environmental changes.
This is an important discovery in the context of climate change and other human-caused environmental transformations. However, the study also highlights that this type of predictability may not hold in all situations, especially when environmental changes are completely new or extreme.
Financing and disclosures
This project received support from various sources, including the Norwegian Research Council, the Swedish Research Council, the European Research Council, the Austrian Science Fund, and the Portuguese Science and Technology Foundation. The research was conducted on animals in Sweden, following strict regulations for the treatment of animals in scientific studies. No significant conflicts of interest were declared by the researchers.
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