Chapter 15: Fungi as symbionts and predators of animals

This Chapter deals with fungal co-operative ventures, including ant agriculture, termite gardeners, and agriculture in beetles. An important co-evolutionary story is that linking anaerobic fungi, the evolution of grasses and the rise of the ruminants a fascinating story that links with human evolution since humans use cereal grasses as staple foods and selected their main food animals from among the ruminants. Finally, we look at the predatory nematode-trapping fungi.

Fungi have co-existed with animals and plants throughout the whole of the evolutionary time since these three groups of higher organisms originally separated from one another. Living together closely for this length of time has given rise to many co-operative ventures. We have already seen how many fungi have combined with plants as partners in mutually beneficial relationships such as mycorrhizas and lichens. In these symbiotic or mutualistic associations the partners each gain something from the partnership so that the association is more successful than either organism alone. The organisms concerned (often two but sometimes more) live in such close proximity to each other that their cells may intermingle and may even contribute to the formation of joint tissues, as they do in the lichen thallus, which is one of the most ancient mutualistic associations of all and found in some of the most inhospitable environments.

Fungi have similarly close relationships with animals, which we will describe in this Chapter. There are several examples and the two about which we know most are:

  • the ‘fungus gardens’ created by leaf-cutter ants and termites (the most notable case being leaf cutter ants which cultivate and then graze upon hyphae, with neither fungus nor ant being able to live without one another), and
  • the chytrid association with ruminants.

These examples show the key features of symbiotic relationships:

  • they are mutually beneficial to the partners,
  • the partners show behavioural and anatomical adaptations to enable the partnership, and
  • the partners can be shown to have evolved in step (‘coevolved’) over a considerable length of time, even to the point that the fungi, and perhaps the animal, cannot survive independently of the partnership. 

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If you want to know more about fungi, you need the 21st Century Guidebook to Fungi.

Ordering details: Moore, D., Robson, G.D. & Trinci, A.P.J. (2011). 21st Century Guidebook to Fungi. Cambridge, UK: Cambridge University Press. ISBN: 9780521186957.

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Updated December 23, 2016