Data from: Is the switch to an ectomycorrhizal state an evolutionary key innovation in mushroom-forming fungi? a case study in the tricholomatineae (agaricales)

Although fungi are one of the most diverse groups of organisms, little is known about the processes that shape their high taxonomic diversity. This study focuses on evolution of ectomycorrhizal (ECM) mushroom-forming fungi, symbiotic associates of many trees and shrubs, in the suborder Tricholomatineae of the Agaricales. We used the BiSSE model and BAMM to test the hypothesis that the ECM habit represents an evolutionary key innovation that allowed the colonization of new niches followed by an increase in diversification rate. Ancestral state reconstruction supports the ancestor of the Tricholomatineae as non-ECM. We detected two diversification rate increases in the genus Tricholoma and the Rhodopolioid clade of the genus Entoloma. However, no increases in diversification were detected in the four other ECM clades of Tricholomatineae. We suggest that diversification of Tricholoma was not only due to the evolution of the ECM lifestyle, but to the expansion and dominance of its main hosts and ability to associate with a variety of hosts. Diversification in the Rhodopolioid clade could be due to the unique combination of spore morphology and ECM habit. The spore morphology may represent an exaptation that aided spore dispersal and colonization. This is the first study to investigate rate shifts across a phylogeny that contains both non-ECM and ECM lineages.尽管真菌是物种多样性最高的生物类群之一，但目前学界对塑造其极高分类多样性的演化过程仍知之甚少。本研究聚焦于伞菌目（Agaricales）口蘑亚目（Tricholomatineae）的外生菌根（ectomycorrhizal, ECM）产蘑菇真菌——一类与多数树木、灌木形成共生关系的真菌类群——的演化历程。我们采用BiSSE模型与BAMM方法，验证了如下假说：外生菌根习性代表一种进化关键创新，能够帮助类群定植新生态位并随之提升多样化速率。祖先状态重建结果显示，口蘑亚目的祖先类群不具备外生菌根习性。我们在口蘑属（Tricholoma）以及粉褶菌属（Entoloma）的红孢类群（Rhodopolioid clade）中检测到两次多样化速率提升事件。然而，在口蘑亚目其余四个外生菌根类群中并未发现多样化速率提升现象。我们认为，口蘑属的多样化不仅源于外生菌根生活方式的演化，还与其主要宿主类群的扩张与占据主导地位，以及该属能够与多种宿主建立共生关系的能力密切相关。红孢类群的多样化则可能源于孢子形态与外生菌根习性的独特组合。其中，孢子形态可能属于一种外适应性状，有助于孢子传播与宿主定植。本研究是首个针对同时包含非外生菌根与外生菌根支系的系统发育树开展演化速率漂移研究的工作。