In a long-term collaboration with the University of Gothenburg, Sweden, led by Dr Hernán Morales these new findings help us to better understand how species adapt to local environments - an important discovery for managing biodiversity in a changing world.
The research compared the whole genomes of 11 different European populations of rough periwinkle snails (Littorina saxatilis) in two rocky-shore habitats, where they adapt to contrasting environments: the first was in sheltered bays dominated by predatory crabs and the second was on rocky headlands dominated by strong wave action.
The team discovered that some parts of the genome appear to be involved in adaptation to the crab and wave habitats in all parts of Europe, suggesting that evolution is highly repeatable in these snails. Other parts of the genome were not differentiated everywhere. This can be explained partly by other types of habitat variation such as the difference between the low shore, near the sea, and the drier areas high on the shore. The crab and wave habitats are separated in different vertical directions in different populations. Areas studied during the research included Sweden, where crab and wave habitats are separated along the shore, Spain with crab habitat above wave habitat, and England with wave habitat above crab habitat. The study discovered that, as a result, natural selection works differently in these locations, going some way to explaining why a number of other studies have previously shown highly repeatable evolution while others have not.
Professor Roger Butlin who leads the team in Sheffield said: "Our snails show divergence between crab and wave environments in thousands of locations around Europe, from metres to thousands of kilometres apart, so they are really a fantastic system for studying repeated evolution!"
Looking to the future, by understanding how the different types of selection - such as crab-wave and shore height - interact, this will better help scientists to predict which populations are most likely to evolve into new species.