Evolutionary History of the Symbiosis Between Fungus-Growing Ants and Their Fungi.

Ignacio H. Chapela, Stephen A. Rehner, Ted R. Schultz, Ulrich G. Mueller

Systematic Botany and Mycology Laboratory, USDA, Beltsville MD 20705
Systematic Botany and Mycology Laboratory, USDA, Beltsville MD 20705
Deptartment of Entomology, Cornell University, Ithaca NY 14853
Section of Neurobiology and Behavior, Cornell Univerisity, Ithaca NY 14853
Science 266: 1691-1694 (1994)

Abstract
The evolutionary history of the symbiosis between fungus-growing ants (Attini) and their fungi was elucidated by comparing phylogenies of both symbionts. The fungal phylogeny based on cladistic analyses of nuclear 28S ribosomal DNA indicates that, in contrast with the monophyly of the ants, the attine fungi are polyphyletic. Most cultivated fungi belong to the basidiomycete family Lepiotaceae; however, one ant genus, Apterostigma, has acquired a distantly related basidiomycete lineage. Phylogenetic patters suggest that some primitive attines may have repeatedly acquired lepiotaceous symbionts. In contrast, the most derived attines have clonally propagated the same fungal lineage for at least 23 million years.
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