Lichen Microbiomes and Growth Rates

Anne Pringle hangs out in cemetaries. She’s not there for the graves, but for what grows on gravestones – lichens. Lichen are a symbiosis between fungi, photosynthetic algae, and bacteria. Functionally an organism, lichen are also their own little ecosystem. Anne studies birth, aging, and death in lichen by tracking their growth on the gravestones.

Lichens grow from their center outwards, so how does the microbiome community differ with the age of the lichen? Older sections of the lichen have a more diverse community and are more unique, while the community at the edges is more similar across lichens. Conversely, the edges are more diverse chemically than the centers (of interest because lichens are known for their secondary metabolite production). Lichens grow outward in a specific manner, described as the reverse of an evaporating coffee drop, where the only variables that matter are the height of the lichen and its photosynthetic efficiency. This growth rate can be modelled, and the predictions of the equations match real world measurement stunningly!

-Alex Linz