The Origin of the Attine Ant-Fungus Mutualism

• Published in: The Quarterly review of biology Vol. 76; no. 2; pp. 169 - 197
• Main Authors: Mueller, Ulrich G., Schultz, Ted R., Currie, Cameron R., Rachelle M. M. Adams, Malloch, David
• Format: Journal Article
• Language: English
• Published: United States University of Chicago Press 01-06-2001; University of Chicago, acting through its Press
• Subjects: Animal behavior; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Ants; Ants - microbiology; Attini; Biological Evolution; Biology; Ecosystem; Evolution; Formicidae; Fossils; Fungal spores; Fungi; Fungi - physiology; Fungiculture; Insect behavior; Insect colonies; Insect ecology; Insect nests; Insect vectors; Insects; Megalomyrmex; Models, Biological; Mutualism; Symbiosis
• ISSN: 0033-5770; 1539-7718
• DOI: 10.1086/393867

Cultivation of fungus for food originated about 45-65 million years ago in the ancestor of fungus-growing ants (Formicidae, tribe Attini), representing an evolutionary transition from the life of a hunter-gatherer of arthropod prey, nectar, and other plant juices, to the life of a farmer subsisting on cultivated fungi. Seven hypotheses have been suggested for the origin of attine fungiculture, each differing with respect to the substrate used by the ancestral attine ants for fungal cultivation. Phylogenetic information on the cultivated fungi, in conjunction with information on the nesting biology of extant attine ants and their presumed closest relatives, reveal that the attine ancestors probably did not encounter their cultivars-to-be in seed stores (von Ihering 1894), in rotting wood (Forel 1902), as mycorrhizae (Garling 1979), on arthropod corpses (von Ihering 1894) or ant faeces in nest middens (Wheeler 1907). Rather, the attine ant-fungus mutualism probably arose from adventitious interactions with fungi that grew on walls of nests built in leaf litter (Emery 1899), or from a system of fungal myrmecochory in which specialized fungi relied on ants for dispersal (Bailey 1920) and in which the ants fortuitously vectored these fungi from parent to offspring nests prior to a true fungicultural stage.