With ∼36,000 described species, Agaricomycetes are among the most successful groups of Fungi. Agaricomycetes display great diversity in fruiting body forms and nutritional modes. Most have pileate-stipitate fruiting bodies (with a cap and stalk), but the group also contains crust-like resupinate fungi, polypores, coral fungi, and gasteroid forms (e.g., puffballs and stinkhorns). Some Agaricomycetes enter into ectomycorrhizal symbioses with plants, while others are decayers (saprotrophs) or pathogens. We constructed a megaphylogeny of 8,400 species and used it to test the following five hypotheses regarding the evolution of morphological and ecological traits in Agaricomycetes and their impact on diversification: 1) resupinate forms are plesiomorphic, 2) pileate-stipitate forms promote diversification, 3) the evolution of gasteroid forms is irreversible, 4) the ectomycorrhizal (ECM) symbiosis promotes diversification, and 5) the evolution of ECM symbiosis is irreversible. The ancestor of Agaricomycetes was a saprotroph with a resupinate fruiting body. There have been 462 transitions in the examined morphologies, including 123 origins of gasteroid forms. Reversals of gasteroid forms are highly unlikely but cannot be rejected. Pileate-stipitate forms are correlated with elevated diversification rates, suggesting that this morphological trait is a key to the success of Agaricomycetes. ECM symbioses have evolved 36 times in Agaricomycetes, with several transformations to parasitism. Across the entire 8,400-species phylogeny, diversification rates of ectomycorrhizal lineages are no greater than those of saprotrophic lineages. However, some ECM lineages have elevated diversification rates compared to their non-ECM sister clades, suggesting that the evolution of symbioses may act as a key innovation at local phylogenetic scales.

伞形孢菌是最成功的真菌类群之一，已描述了约 36,000 种物种。伞形孢菌在子实体形态和营养模式方面表现出极大的多样性。大多数具有绒毛柄子实体（带有菌盖和茎），但该类群还包含壳状复生真菌、多孔菌、珊瑚真菌和囊状真菌（例如马勃和臭角）。一些伞形孢菌与植物形成外生菌根共生体，而另一些则是腐烂菌（腐生菌）或病原体。我们构建了 8,400 个物种的宏系统发育，并用它来测试以下五个关于伞形孢菌形态和生态特征的进化及其对多样化的影响的假设：1) 反旋形式是拟形的，2) 菌毛-柄形式促进多样化，3)胃类固醇形式的进化是不可逆的，4）外生菌根（ECM）共生促进多样化，5）ECM共生的进化是不可逆的。伞形孢菌的祖先是具有复生子实体的腐生菌。在所检查的形态学中有 462 个转变，其中包括 123 个小行星形式的起源。胃类固醇形式逆转的可能性极小，但不能否认。伞菌柄形式与多样化率升高相关，表明这种形态特征是伞形孢菌成功的关键。ECM 共生在伞形孢菌中已经进化了 36 次，其中有几次转变为寄生。在整个 8,400 个物种的系统发育中，外生菌根谱系的多样化率并不高于腐生菌根谱系的多样化率。然而，与非 ECM 姐妹进化枝相比，一些 ECM 谱系的多样化率较高，这表明共生进化可能是局部系统发育尺度的关键创新。