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One of the most amazing and inconspicuously beautiful organisms is the Lichen. They’re essentially Symbiotic, composite organismsIt is made from a combination of a fungus and cyanobacterium living in the filaments. Lichens can grow almost anywhere, including in the Arctic tundra or on the bark of trees in your yard. This apparent resilience is being challenged however by climate change, which has shown that they have a difficult time adapting to rising temperatures.
Matthew Nelsen, Field Museum Chicago, and his colleagues studied how climate preferences for lichen change over time. This was also related to the climate crisis. As it turns out, they shift temperature preferences by less than 1ºC every million years. This is lower that the global warming of up to 3ºC predicted.
“Our initial motivation was to better understand how this important group of algae had diversified to collectively occupy an extremely wide range of climates across the globe,” Nelsen told ZME Science. “It was an exciting opportunity for us to use the past to make predictions about how these algae may be affected by modern climate change.”
Exploring lichens
Nelsen and his colleagues focused on one genus of algae. TrebouxiaIt is found in approximately 7000 species. When algae take residence inside a lichen, they live with the fungus as one — each providing something that benefits the whole. The fungus provides the structure and the food, while the algae provide the food.
The team collected a lot of data about Trebouxia locations around the globe, including observations of the climate conditions in each location. They also used a Trebouxia genome database to create a tree for the alga. This information was used to determine how quickly Trebouxia had adapted to changing climates in the past.
They discovered that the changes in the climate preferences of algae occur slowly over the course a few millions of years. Trebouxia is likely going to be affected by the rapid climate changes that are currently taking place on the planet. If they can’t adapt fast enough, they might have to modify at least part of their current range.
According to the researchers, Trebouxia is likely to disappear from many of the areas where lichens depend on it. Some may migrate to more suitable climate conditions, but there are limits to where the lichens can spread.
Fewer lichens would have deep consequences on ecosystems, as they are the dominant vegetation on 7% of the Earth’s surface, Nelsen said. They are essential for ecosystem hydrology and for carbon and nitrogen cycle. But there’s no need to despair. He said that we can still reduce our emissions and continue research on lichens.
“One question that has repeatedly come up is whether the fungal partners exhibit a similarly low historic rate of change. This would be especially interesting to pursue,” Nelsen said. “It would also be wonderful to have experimental data demonstrating the thermal limits and optima of these algae to gain a better understanding of them.”
The study was published by the journal Frontiers.
