The symbiotic partnership algae that make up lichens are adapting to changing climates at an extremely slow rate, a new study suggests.
A single degree increase in the temperature of the atmosphere would threaten the most important symbiotic partnership in the living world. “Lichens, composite organisms made of cyanobacteria or algae associated with a fungus, might disappear due to climate change due to the slow rate at which their algal component evolves”, announce the New Scientist.
The weekly echoesa study published on February 15 in Frontiers in Microbiology, for which researchers have focused on Trebouxia, a genus of single-celled green algae associated with fungus in over 7,000 species of lichens. By collecting data on numerous specimens around the world and then using genetic information to build a “family tree” of this algae, the team estimated how long it took to Trebouxia and therefore to lichens to adapt to climate changes that have occurred in the past.
The researchers discovered that this algae was particularly slow to adapt, changing its temperature preferences by less than 1°C every million years. “This rate is significantly lower than the 1 to 4°C increase in global temperatures projected for the next eighty years”, pointed out Matthew Nelsen, du Field Museum Chicagofirst author of the study.
Study the fungal partner
According to him, lichens depending on Trebouxia may migrate to places where the temperature and humidity would be more acceptable to them, but most will disappear from where they are currently found. “All of this might have far-reaching ecological consequences,” deplore the New Scientist.
Lichens play a fundamental role in stabilizing soils and retaining moisture, and they can serve as food or shelter for some animals.”
The next step for researchers will need to consider fungal partners and their ability to adapt to climate to better assess lichen survival. Laboratory studies might also help better understand the thermal limits of algal symbionts.
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