To elucidate parasitic interactions comprising effects of fungal parasites on lichens, Merinero and Gauslaa ran a growth-chamber experiment to assess the effects of the specialised fungi Plectocarpon lichenum and P. scrobiculatae on the fitness of their lichen hosts Lobaria pulmonaria and L. scrobiculata.
Growth rates of infected and non-infected lichens were compared. Infected lichens grew much less than the non-infected plants, and lichen growth rates decreased with increasing parasite abundance. This study shows for the first time that specialised fungal parasites directly reduce lichen fitness, thereby expanding our understanding of parasitic interactions involving lichens and specialised lichenicolous fungi.
Merinero, S., & Gauslaa, Y. (2017). Specialized fungal parasites reduce fitness of their lichen hosts. Annals of Botany, 121(1), 175–182. https://doi.org/10.1093/aob/mcx124