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17.2: Types of Mutualisms

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    Resource-resource relationships

    Mutualistic relationships can be thought of as a form of "biological barter" (Ollerton 2016). For example, in mycorrhizal associations between plant roots and fungi, with the plant providing food resources (ie, carbohydrates) to the fungus in return for other important nutrients (eg, nitrogen and phosphorous). Other examples include rhizobia bacteria that fix nitrogen for leguminous plants (family Fabaceae) in return for energy-containing carbohydrates (Denison and Kiers 2004).

    Service-resource relationships

    A few birds are perched, eating ticks off of various body parts of an impala standing in a field.

    Figure \(\PageIndex{1}\): The red-billed oxpecker eats ticks on the impala's coat, in a cleaning symbiosis. Photograph by Muhammad Mahdi Karim.

    Service-resource relationships are common. Three important types are pollination, cleaning symbiosis, and zoochory. In pollination, a plant trades food resources in the form of nectar or pollen for the service of pollen dispersal. Cleaning symbioses are carried out by Phagophiles, animals that feed on ectoparasites, thereby providing anti-pest service, as in cleaning symbiosis. Elacatinus and Gobiosoma, genera of gobies, feed on ectoparasites of their clients while cleaning them (Soares et al. 2008). Zoochory is the dispersal of the seeds of plants by animals. This is similar to pollination in that the plant produces food resources (for example, fleshy fruit, overabundance of seeds) for animals that disperse the seeds (service). Plants may advertise these resources using color (Lim and Burns 2021) and a variety of other fruit characteristics. Another example is ant protection of aphids, where the aphids trade sugar-rich honeydew (a by-product of their mode of feeding on plant sap) in return for defense against predators such as ladybugs.

     

    Service-service relationships

    Decorative

    Figure \(\PageIndex{2}\): Ocellaris clownfish and Ritter's sea anemones live in a mutual service-service symbiosis, the fish driving off butterflyfish and the anemone's tentacles protecting the fish from predators. Photograph by Jan Derk is in the Public Domain.

    Strict service-service interactions are very rare, for reasons that are far from clear (Ollerton 2006). One example is the relationship between sea anemones and anemone fish in the family Pomacentridae: the anemones provide the fish with protection from predators (which cannot tolerate the stings of the anemone's tentacles) and the fish defend the anemones against butterflyfish (family Chaetodontidae), which eat anemones. However, in common with many mutualisms, there is more than one aspect to it: in the anemonefish-anemone mutualism, waste ammonia from the fish feeds the symbiotic algae that are found in the anemone's tentacles (Porat and Chadwick-Furman 2004; Porat and Chadwick-Furman 2005). Therefore, what appears to be a service-service mutualism in fact has a service-resource component. A second example is that of the relationship between some ants in the genus Pseudomyrmex and trees in the genus Acacia, such as the whistling thorn and bullhorn acacia. The ants nest inside the plant's thorns. In exchange for shelter, the ants protect acacias from attack by herbivores (which they frequently eat when those are small enough, introducing a resource component to this service-service relationship) and competition from other plants by trimming back vegetation that would shade the acacia. In addition, another service-resource component is present, as the ants regularly feed on lipid-rich food-bodies called Beltian bodies that are on the Acacia plant (Palomar College 2019).

     

    References 

    Denison, R.F., & Kiers, E.T. (2004). Why are most rhizobia beneficial to their plant hosts, rather than parasitic. Microbes and Infection, 6(13), pp. 1235–1239. doi:10.1016/j.micinf.2004.08.005. PMID 15488744.

    Soares, M.C., Côté, I.M., Cardoso, S.C., & Bshary, R. (2008). The cleaning goby mutualism: A system without punishment, partner switching or tactile stimulation. Journal of Zoology, 276(3), pp. 306–312. doi:10.1111/j.1469-7998.2008.00489.x.

    Lim, G., & Burns, K.C. (2021). Do fruit reflectance properties affect avian frugivory in New Zealand? New Zealand Journal of Botany, pp. 1–11. doi:10.1080/0028825X.2021.2001664. ISSN 0028-825X. S2CID 244683146.

    Ollerton, J. (2006). 'Biological barter': Interactions of specialization compared across different mutualisms. In Waser, N.M., & Ollerton, J. (Eds.), Plant-pollinator interactions: From specialization to generalization (pp. 411-435). University of Chicago Press.

    Porat, D., & Chadwick-Furman, N.E. (2004). Effects of anemonefish on giant sea anemones: Expansion behavior, growth, and survival. Hydrobiologia, 530(1–3), pp. 513–520. doi:10.1007/s10750-004-2688-y. S2CID 2251533.

    Porat, D., & Chadwick-Furman, N.E. (2005). Effects of anemonefish on giant sea anemones: Ammonium uptake, zooxanthella content and tissue regeneration. Mar. Freshw.Behav. Phys., 38, pp. 43–51.

    "Swollen Thorn Acacias". www2.palomar.edu. Retrieved 22 February 2019.

    Contributors and Attributions

    This chapter was written by Aaron Howard with text taken from the following CC-BY resources: 

    17.2: Types of Mutualisms is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by LibreTexts.