Adapting to climate change in rock crevices
Lichens are really tough customers. Certain species can be found in all seven continents. Others can even survive in outer space: in 2005, two species of lichen were observed engaging in photosynthesis after spending 15 days on the outer casing of a satellite orbiting the Earth. Biologist Ulrike Ruprecht from the University of Salzburg has dedicated her career to lichens. “They can withstand extreme climatic conditions. That's why I'm so intrigued by them,” she says. In a current FWF-funded research project, Rupprecht is investigating the interrelationship between climate, diversity and the distribution of lichens – and how these resilient organisms cope with global warming.
Probably the world’s longest known symbiosis
There are an estimated 19,000 species of lichen worldwide. A closer look reveals that they consist of a diverse and complex symbiotic association. The bulk of the lichen body is made up of a fungus in which single-cell algae are embedded. The fungus provides them with a habitat directly beneath its surface and offers protection – from light radiation, for instance. The fungus in turn obtains energy by tapping into the carbohydrates that the algae produce through photosynthesis.
“In addition to the two primary symbionts, we often find many other fungi and algae in or on the lichen body,” notes Ruprecht. Each lichen also has its own microbiome, which is composed of a myriad of bacteria. “Lichens obtain their nutrients from the air – for instance through rain, fog, or wind. The bacteria then process the nutrients obtained in this way and make them available to the fungus,” Rupprecht explains. She analyzes changes in the so-called lichen holobiome – i.e. the specific composition of fungi, algae, and the microbiome.
Lichens as climate sensors
Biologist Ulrike Ruprecht is conducting research in Antarctica and the Alps to find out how climate warming is changing the biodiversity and growth of extremely resilient lichens. These borderline species are particularly sensitive to environmental changes.
Researching the (almost) indestructibles
Ulrike Ruprecht is decoding the composition of lichen holobiomes found in the Alps and Antarctica. She is interested in the influence that temperature, humidity, and pressure have on the complex symbiosis of fungi, algae, and bacteria. This, in turn, allows her to get a glimpse of what a warmer future might bring.
Ruprecht’s focus is on the toughest of them all: the so-called crustose lichens, which attach themselves to hard surfaces such as rocks and are to be found all over the world. In Antarctica, 99.82 percent of which is covered by ice, lichens and mosses are the most important elements of vegetation. “When lichens are dry, they are almost indestructible. When it gets humid, for example when snow melts or fog comes in, they are reactivated and trigger their metabolism,” explains Ulrike Ruprecht.
Of rough crossings, scalpels, and snowshoes
The lichen researcher herself is also tough. She has traveled to Antarctica several times to collect lichen samples. Most recently, in 2018, she spent four days aboard the Spanish polar research vessel Hespérides crossing the Drake Passage, which is notorious for its extremely high waves. “That crossing was a really rough experience,” recalls Ruprecht. For this field research she spent several weeks at the Spanish polar research station Juan Carlos I in the maritime Antarctic on Livingston Island at latitude 62 degrees south. For further research, she flew to New Zealand’s research station Scott Base in continental Antarctica.
In search of lichens, the biologist hiked across Antarctic glaciers on snowshoes, flew by helicopter to dry valleys in continental Antarctica, and, wrapped up in a heavy wetsuit, traveled by dinghy to more remote collection sites. Using a sterile scalpel, she scraped hundreds of lichen samples from rocks into specially prepared tubes. These samples supplement a data set she has been compiling for two decades on several expeditions and in collaboration with colleagues. They serve as a basis for predicting future developments in the context of climate change.
Retreats and new habitats
In a recently published study, doctoral student Anna Götz analyzed 673 Antarctic samples from this dataset. Among other things, she calculated how the distribution areas of the nine most common and widespread Antarctic crustose lichen species are set to change under three different climate scenarios by the year 2100.
The outcome: in maritime Antarctica, some species will see their habitat shrink. The situation is different in three colder and drier regions of continental Antarctica. In these regions, most species will be able to expand their habitats by the end of the century – even in the event of extreme warming. According to the calculations, many species would then migrate inland. “When the ice melts, many crustose lichens will find a new habitat,” explains Ulrike Ruprecht.
Generalists among lichens stand particularly good chances in this context. Lecidea cancrifomis, a lichen fungus of the Lecidea family, for example, can form a symbiosis with all types of algae. “But many lichen fungi are relatively specialized to certain Antarctic habitats,” notes Ruprecht. They will, as a rule, find it more difficult to cope with a warmer climate.
Who will survive warmer times?
Adaptation is more difficult in the Alps than in Antarctica. “Sooner or later, the mountain top is the last option – and that's it,” says Ruprecht, who now wants to find out how changes in variables such as temperature or humidity influence the composition of the lichen holobiome.
Together with doctoral student Anna Götz and equipped with scalpels and a great many test tubes, she roamed the Hohe Tauern National Park in the summer of 2023. They collected a total of 175 samples at locations ranging in altitude between 1,170 and 3,000 meters above sea level. First analyses reveal that the composition of the lichen holobiome clearly changes at different altitudes.
The researchers are currently examining the holobiome of 250 samples from Antarctica, the Alps, and southern South America – focusing primarily on lichen species that occur at several locations. “We are analyzing how the lichen holobiome differs along climatic gradients,” explains Ruprecht. In simplistic terms, climatic gradients describe the time- or space-related changes in measured values, such as air temperature across altitudes or from north to south. However, it takes time and computing power to arrive at findings.
Tiny organisms, huge data sets
As a first step, the researchers need to decode the molecular blueprint of the samples, i.e., analyze a molecule which contains genetic information encoded in four bases: the DNA. For this purpose, Ulrike Ruprecht first treats the samples with liquid nitrogen. “Lichens are stable things, after all. It's not exactly easy to extract their DNA,” she notes.
In a next step, the entirety of DNA is extracted from the sample, which consists of a variety of different algae, fungi, and bacteria. So-called primers help to identify which organisms the sample contains. Primers are individual, artificially produced pieces of DNA that bind with and mark a specific part of the DNA, thereby multiplying a clearly defined part of the DNA. This part is then sequenced. “By now we have primers for every piece of the genome,” explains Ulrike Ruprecht. At the end of the process, she matches the sequences in a database, thus learning which organisms the sample contained.
The researchers then link these data to 19 so-called climate variables, which are calculated from the temperature and precipitation at the location where the sample was taken. Latitude and altitude are also taken into account. All data are then fed into statistical models. With the help of ecological niche modeling, the current and future distribution areas of individual lichen species can be calculated. The analysis helps to show which lichen with which holobiome occurs at which location – and whether it will be there in the future. “Our findings enable us to deduce which species will continue to spread in the future, which ones will decline, and where they will migrate to,” says Ulrike Ruprecht. “I am very keen to see what else we will find.”
About the researcher
Ulrike Ruprecht is a postdoctoral researcher and project manager in the Department of Environment and Biodiversity at the Salzburg Paris Lodron University. She holds a PhD in ecology with a focus on biodiversity, lichenology (the study of lichens), and evolutionary systematics. Her research focuses on cold-adapted organisms, in particular rock-dwelling crustose lichens in polar and high alpine habitats. Set to run until the end of 2026, the research project “Lichen holobiome diversity along climatic gradients” has been awarded EUR 343,000 in funding from the Austrian Science Fund (FWF).
Publications
Future range shifts and diversity patterns of Antarctic lecideoid lichens under climate change scenarios, in: Global Change Biology Communications 2025
Aurantiothallia and Hertelaria, two new genera of porpidioid Lecideaceae (Ascomycota, Lecanoromycetidae, Lecideales), and other new porpidioid taxa from Tasmania, in: The Lichenologist 2025
Two new species of the genus Lecidella (Lecanoraceae, Ascomycota) from maritime Antarctica, southern South America and North America, in: The Lichenologist 2024
