Agarics--fungi that include the common mushroom--are diverse in morphology and in ecological niche: puffballs, gilled mushrooms, decomposers of wood, and mutualistic partners to ants. Alas, tracing their evolutionary radiations has been hampered by the dearth of fossil samples.
Garnica et al. have performed a molecular analysis of nuclear genes and a microscopic analysis of agaric spore structures in order to better understand the organization of this group. Using these two features, they rearranged relationships, such that some species were flung apart and others recognized as more closely related than previously thought. It appears that one major evolutionary innovation led to the acquisition of thicker walls and darker pigmentation of the spores. The authors suggest that these sturdier spores were better able to tolerate the relatively harsher conditions on dry land (and, in some cases, in herbivore digestive tracts), where water conservation and resistance to ultraviolet radiation can be a great help. -- PJH
Mycol. Res. 111, 10.1016/j.mycres.2007.03.019 (2007).
