Ectomycorrhizal fungi have larger fruit bodies than saprotrophic fungi

• Fruit body and spore characteristics differ between fungal trophic guilds.
• Saprotrophs produce on average smaller fruit bodies than mutualistic species.
• Both guilds did not differ in spore size and spore shape.
• We argue that difference in fruit body size is related to resource availability.

Currently we have only a limited understanding of the evolutionary and ecological significance of reproductive traits of fungi. We compared data on fruit body size, spore size and shape between saprotrophic and mutualistic (ectomycorrhizal) fungi in Northern and Central Europe. Lifestyle and reproductive traits showed strong phylogenetic signals. A phylogenetically informed analysis demonstrated that saprotrophs produce on average smaller fruit bodies than mutualistic species. The two guilds, however, do not differ in spore size. Overall this suggests that fruit bodies of ectomycorrhizal fungi produce on average more spores than saprotrophic fungi. We argue that this difference is related to resource availability: ectomycorrhizal fungi receive carbon from their hosts and, therefore, evolution favours large fruit bodies, whereas the fruit body size of saprotrophic fungi might have responded to resource availability and the distribution and size of resource patches.