Mutualism (biology)

Mutualism has also been linked to major evolutionary events, such as the evolution of the eukaryotic cell (symbiogenesis) and the colonization of land by plants in association with mycorrhizal fungi.

Other examples include rhizobia bacteria that fix nitrogen for leguminous plants (family Fabaceae) in return for energy-containing carbohydrates.

[11] Metabolite exchange between multiple mutualistic species of bacteria has also been observed in a process known as cross-feeding.

However, daciniphilous Bulbophyllum orchid species trade sex pheromone precursor or booster components via floral synomones/attractants in a true mutualistic interactions with males of Dacini fruit flies (Diptera: Tephritidae: Dacinae).

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.

[21] In the neotropics, the ant Myrmelachista schumanni makes its nest in special cavities in Duroia hirsute.

For example, zebra (Equus burchelli) and wildebeest (Connochaetes taurinus) can remain in association during periods of long distance migration across the Serengeti as a strategy for thwarting predators.

Symbiogenesis, a leading theory on the evolution of Eukaryotes states the origin of the mitochondria and cell nucleus emerged from a parasitic relationship of ancient Archaea and Bacteria.

Under certain conditions species of fungi previously in a state of mutualism can turn parasitic on weak or dying plants.

In models of mutualisms, the terms "type I" and "type II" functional responses refer to the linear and saturating relationships, respectively, between the benefit provided to an individual of species 1 (dependent variable) and the density of species 2 (independent variable).

As the mutualistic interactive term β is always positive, this simple model may lead to unrealistic unbounded growth.

In 1989, David Hamilton Wright modified the above Lotka–Volterra equations by adding a new term, βM/K, to represent a mutualistic relationship.

[32] Wright also considered the concept of saturation, which means that with higher densities, there is a decrease in the benefits of further increases of the mutualist population.

Without saturation, depending on the size of parameter α, species densities would increase indefinitely.

[citation needed] In 1959, C. S. Holling performed his classic disc experiment that assumed that where The equation that incorporates Type II functional response and mutualism is: where or, equivalently, where This model is most effectively applied to free-living species that encounter a number of individuals of the mutualist part in the course of their existences.

vs. M. Mutualistic networks made up out of the interaction between plants and pollinators were found to have a similar structure in very different ecosystems on different continents, consisting of entirely different species.

[38] This simultaneous collapse occurs, because pollinator species depend on each other when surviving under difficult conditions.

[39] Infestations of head lice might have been beneficial for humans by fostering an immune response that helps to reduce the threat of body louse borne lethal diseases.

For example, beans may grow up cornstalks as a trellis, while fixing nitrogen in the soil for the corn, a phenomenon that is used in Three Sisters farming.

[42] One researcher has proposed that the key advantage Homo sapiens had over Neanderthals in competing over similar habitats was the former's mutualism with dogs.

[45] The gut microbiota, containing trillions of microorganisms, possesses the metabolic capacity to produce and regulate multiple compounds that reach the circulation and act to influence the function of distal organs and systems.

This pattern is generalized beyond bacteria by Yamada et al. 2015's demonstration that undernourished Drosophila are heavily dependent on their fungal symbiont Issatchenkia orientalis for amino acids.

For example, plant lineages inhabiting nutrient-rich environments have evolutionarily abandoned mycorrhizal mutualisms many times independently.