The difference between organelles and endosymbionts

or are they resolved? Both the ants and the termites cultivate their fungal crops in monocultures. This is remarkable, because there is ample genetic variation of fungal strains across colonies so that horizontal transmission should at least occasionally (in the ants) or regularly (in most termites) establish genetically variable fungus gardens. In the ants, monocultures are actively enforced because fungal incompatibility compounds hitchhike through the ant guts to be expressed in the feces that fertilize new implants of somatic fungal fragments [14]. The termites, however, propagate their symbionts within colonies by asexual spores that they embed in newly deposited fecal substrate. This system is therefore expected to produce symbiont monocultures by a combination of genetic drift and selection for rapid spore formation, rather than by active competition via incompatibility compounds [11,12]. Can we learn something from the sustainable farming practices of insect societies? The farming insect societies had tens of millions of years of natural selection to solve many of the challenges that are also well known to human farmers. They have conveyor belt substrate processing, produce their own pesticides and antibiotics, and practice active waste management [1]. Neither the ants, nor the termites, however, have been able to overcome the fundamental laws of host– symbiont conflicts, which imply that only monoculture farming is evolutionarily stable. Our own farming practices evolved culturally by frequent exchange of crops, learning and copying innovative practices. The problem is that, on the larger scale that we apply today, many of these practices are unlikely to be sustainable, even on an ecological time scale. It may be, therefore, that further research on the long-term evolutionary stable farming systems of the ants and termites may provide useful lessons for our own future food production. The evolution of fungus-growing termites and their mutualistic fungal symbionts. A general model for the evolution of mutualisms. (1999). Fungus-growing ants use antibiotic-producing bacteria to control garden parasites. (2002). Extensive exchange of fungal cultivars between sympatric species of fungus-growing ants. Mol. As you reap, so shall you sow: coupling of inoculating and harvesting stabilizes the mutualism between termites and fungi. Ant versus Fungus versus Mutualism: Ant-cultivar conflict and the deconstruction of the attine ant-fungus symbiosis. Three recent contributions in Current Biology [1–3] have addressed new findings on the classical cyanobacterial endosymbiont of Paulinella chromatophora, but refer to the endosymbiont as a 'plastid'. Yoon et al. [2] even opine that Paulinella " has …