Reciprocal genomic evolution in the ant-fungus agricultural symbiosis

Nat Commun. 2016 Jul 20;7:12233. doi: 10.1038/ncomms12233.

Abstract

The attine ant-fungus agricultural symbiosis evolved over tens of millions of years, producing complex societies with industrial-scale farming analogous to that of humans. Here we document reciprocal shifts in the genomes and transcriptomes of seven fungus-farming ant species and their fungal cultivars. We show that ant subsistence farming probably originated in the early Tertiary (55-60 MYA), followed by further transitions to the farming of fully domesticated cultivars and leaf-cutting, both arising earlier than previously estimated. Evolutionary modifications in the ants include unprecedented rates of genome-wide structural rearrangement, early loss of arginine biosynthesis and positive selection on chitinase pathways. Modifications of fungal cultivars include loss of a key ligninase domain, changes in chitin synthesis and a reduction in carbohydrate-degrading enzymes as the ants gradually transitioned to functional herbivory. In contrast to human farming, increasing dependence on a single cultivar lineage appears to have been essential to the origin of industrial-scale ant agriculture.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Agriculture*
  • Animals
  • Ants / genetics*
  • Calibration
  • Carbohydrate Metabolism / genetics
  • Chitin / metabolism
  • Crops, Agricultural / genetics
  • Domestication
  • Evolution, Molecular*
  • Fungi / genetics*
  • Genome*
  • Genome, Insect
  • Genome, Plant
  • Phylogeny
  • Sequence Analysis, DNA
  • Symbiosis / genetics*
  • Time Factors

Substances

  • Chitin