Farming practices, in which one organism (here: "the host") promotes the growth of the organism it relies on for food (here: "the symbiont"), are not restricted to human hosts. Among the non-human farmers, ants are particularly successful. Farming is an example of mutualism: an interaction between different species which is beneficial for all those involved. The evolutionary stability of mutualism in the light of potential conflicts of interests between the partners still remains incompletely understood. Various mechanisms may aid alignment of differing interests and resolve host-symbiont conflicts. Farming mutualisms are well-suited for studying these mechanisms. The three most important arenas of potential conflict in farming mutualisms concern symbiont reproduction, symbiont transmission / dispersal and symbiont (genetic) diversity. Here, these three symbiont characteristics and the control mechanisms governing them are reviewed for the two best-known cases of ant fanning: (1) fungus-growing by attine ants and (2) Homoptera-tending by various groups of ants. Cross-system comparison of these ant farming systems highlights several universal patterns potentially governing the evolutionary stability of these successful mutualisms: Many systems are characterised by reduced symbiont dispersal and diversity (often in association with asexual reproduction and vertical transmission), possibly promoted by specific ant behaviours, such as creation of protective environments. Frequently, these systems function as networks, with the focal species interacting with additional species, highlighting a promising new take on classic mutualisms.
|Status||Published - sep-2015|