Normally, scientists have believed that it takes countless centuries for evolution to produce major changes in any species. However, a new study has witnessed this amazing process unfold in a figurate blink of an eye.
A team of researchers from the Institute of Science and Technology Austria (ISTA) and Norway’s Nord University have observed marine snails evolve to closely resemble their predecessors over just 30 years – which is a tiny fraction of time in evolutionary terms.
The story begins in 1988 when a toxic algal bloom wiped out populations of marine snails from small rocky outcrops, known as skerries, in the Koster archipelago near the Swedish-Norwegian border. While this environmental disaster might have seemed insignificant to most, for marine ecologist Kerstin Johannesson from the University of Gothenburg, it presented a unique opportunity to study evolution in action.
Four years after the algal bloom, in 1992, Johannesson decided to reintroduce snails to one of these now-empty skerries. Here’s the twist: instead of bringing back the same type of snails that previously lived there, she introduced a distinctly different population of the same species, Littorina saxatilis.
These marine snails, commonly found along North Atlantic shores, have evolved different traits to suit their specific environments. The two main types are known as “Wave snails” and “Crab snails.” Wave snails, which originally inhabited the skerries, are small with thin shells, large, rounded openings, and bold behavior – adaptations that help them survive in wave-battered environments. Crab snails, on the other hand, are larger with thicker shells, smaller elongated openings, and more cautious behavior – traits that protect them from crab predators in calmer waters.
Johannesson’s experiment involved introducing Crab snails to the skerry that had previously been home to Wave snails. The question was: How would these Crab snails adapt to their new wave-exposed environment?
The results published in the journal Science Advances were nothing short of remarkable. Within just a few generations – snails reproduce once or twice a year – scientists began to see evidence of adaptation. Over the course of 30 years, the transplanted Crab snails evolved to closely resemble the Wave snails that had inhabited the skerry before the algal bloom.
“Over the experiment’s 30 years, we were able to predict robustly what the snails will look like and which genetic regions will be implicated. The transformation was both rapid and dramatic,” says Diego Garcia Castillo, a graduate student at ISTA and one of the study’s lead authors, in a media release.
What makes this study particularly fascinating is that the snails didn’t evolve these new traits from scratch. Instead, they tapped into genetic diversity that was already present in their population, albeit at low levels. This existing genetic variation, combined with possible gene flow from neighboring Wave snail populations, allowed for rapid adaptation to the new environment.
The implications of this study extend far beyond the world of snails. In an era of rapid environmental change, understanding how species can adapt quickly is crucial.
“This work allows us to have a closer look at repeated evolution and predict how a population could develop traits that have evolved separately in the past under similar conditions,” explains Garcia Castillo.
Anja Marie Westram, a researcher at Nord University and co-corresponding author of the study, emphasizes the importance of genetic diversity in adaptation.
“Not all species have access to large gene pools and evolving new traits from scratch is tediously slow. Adaptation is very complex and our planet is also facing complex changes with episodes of weather extremes, rapidly advancing climate change, pollution, and new parasites,” says Westram. “Perhaps this research helps convince people to protect a range of natural habitats so that species do not lose their genetic variation.”
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 the key to their survival. This study provides a glimpse into how evolution can work on relatively short timescales, offering hope for species facing rapid environmental changes.
Source: https://studyfinds.org/snail-evolution-in-real-time/