Dentinger, Bryn T. M.;
Lodge, D. Jean;
Munkacsi, Andrew B.;
Desjardin, Dennis E.;
McLaughlin, David J.
Phylogenetic Placement of an Unusual Coral Mushroom Challenges the Classic Hypothesis of Strict Coevolution in the Apterostigma pilosum Group Ant-Fungus Mutualism
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Media type:
E-Article
Title:
Phylogenetic Placement of an Unusual Coral Mushroom Challenges the Classic Hypothesis of Strict Coevolution in the Apterostigma pilosum Group Ant-Fungus Mutualism
Contributor:
Dentinger, Bryn T. M.;
Lodge, D. Jean;
Munkacsi, Andrew B.;
Desjardin, Dennis E.;
McLaughlin, David J.
Description:
<p>The ~50 million-year-old fungus-farming ant mutualism is a classic example of coevolution, involving ants that subsist on asexual, fungal biomass, in turn propagating the fungus clonally through nest-to-nest transmission. Most mutualistic ants cultivate two closely related groups of gilled mushrooms, whereas one small group of ants in the genus Apterostigma cultivates a distantly related lineage comprised of the G2 and G4 groups. The G2 and G4 fungi were previously shown to form a monophyletic group sister to the thread-like coral mushroom family Pterulaceae. Here, we identify an enigmatic coral mushroom that produces both fertile and sterile fruiting structures as the closest free-living relative of the G4 fungi, challenging the monophyly of the Apterostigma cultivated fungi for the first time. Both nonparametric bootstrap and Bayesian posterior probability support the node leading to the G4 cultivars and a free-living Pterula mushroom. These data suggest three scenarios that contradict the hypothesis of strict coevolution: (1) multiple domestications, (2) escape from domestication, (3) selection of single cultivar lineages from an ancestral mixed-fungus garden. These results illustrate how incomplete phylogenies for coevolved symbionts impede our understanding of the patterns and processes of coevolution.</p>