Lichens, whether growing on rock or vegetation, play surprising and complex roles in the ecosystem. Steve Leavitt, an evolutionary biologist at Brigham Young University, is curator of the lichen collection at the BYU Museum of Life Sciences. This week, we talked to Steve about what lichens are made of and why we should care about the colorful and unique life forms.
Science Moab: Lichens require two organisms – fungi and algae – to exist. How does this work?
Leavitt: One of the partners in a symbiotic relationship, in evolutionary terms, is always trying to get the upper hand. The iconic image that comes to mind is that they are coming together and helping each other, but in reality, it is more complex than that. With the lichen, the fungus is creating a structure in which the algae can survive: it’s controlling UV radiation and creating a nice little growth room for the algae. And in return, the algae return the sugars to the fungi. It is like a fungus discovered in agriculture. There is something evolutionarily advantageous that comes from this specific exchange of goods—so good that lichens have evolved independently several times.
Moabi Science: What attracts some lichens to grow on rocks, as opposed to living organisms like trees?
Leavitt: The beauty of a rock face, especially one that is exposed and hot, is that there is no competition. If you can survive, you have the real estate all to yourself. This may be one of the reasons why lichens evolved: those sugars from the algae can actually be used to help protect the whole organism from drying out. So when the fungus discovers a way not to use those polysaccharides for energy, but instead to store them for protection from desiccation, it is able to colonize these new and unique habitats. Lichens in other countries are surviving in another country. But what they both have in common is the reliance on a fungus, an algae, and a whole host of microbes to survive. You can have large three-dimensional macrolichens with the same common ancestor as some small and tiny crustose lichens that you never see.
Moabi Science: So why should people study lichens?
Leavitt: They are strange, interesting, and part of this incredible array of diversity on Earth. For me, it’s just that there are questions to be answered. We can go back into the deepest geological time and realize that lichens are fundamentally important to the formation of the earth. They slowly erode or degrade the rocks until we end up with productive soils. In other cases, they stabilize the soil through biological soil crusts, or help vascular plants to facilitate more effective water infiltration to better retain soil moisture. Lichens have several important ecological roles.
Science Moab: What exactly are you studying right now?
Leavitt: I am into a bit of anything that is lichen, or even potentially lichen related! We have several projects going on in the La Sal Mountains, where there are large lichens that drink from conifers. It looks like something you’d see in Alaska or British Columbia, and there’s nowhere else in the state where this happens. So we are interested to ask, what are those processes that facilitated the formation of these really cool macrolichen communities?
We’re interested in using lichens as biomonitors as well—we can go out and collect a lichen that’s been sitting on a rock for decades, grind it up, and analyze the concentrations for potential contaminants like lead, iron, or titanium. . . And then we can use them as proxies to look at air quality.
Lichen can also tell us about dust deposition, which actually has some pretty significant impacts on human health. Different dust sources have different signatures, so we can go through and match those profiles to dust from a specific region.
Science Moab: These amazing, colorful, diverse shapes have endless potential for intricate designs. Can you tell anything visually? Why does lichen have all these different variations?
Leavitt: Many of the colors we see are manufactured for sunscreen. If you go out and see a bunch of orange lichens growing on exposed sandstone, it’s likely that those compounds are produced by the fungus as a sunscreen to protect the algae. Other times, you might see a beautiful green lichen growing on a rock and think it’s the algae that’s making it green—but in fact, it’s the usnic acid that the fungus produces as an anti-herb, to keep snails so they don’t chew it. Forms, meanwhile, are for water or heat treatment methods.
What we are seeing is the interaction between multiple organisms that have evolutionary adaptations that allow them to preferentially succeed, survive and reproduce.
Science Moab is a non-profit organization dedicated to engaging community members and visitors with the science happening in Southeastern Utah and the Colorado Plateau. To learn more and listen to the rest of this interview, visit www.sciencemoab.org/radio. This interview has been edited for clarity.