Mutualism and its Importance
– Mutualism is an ecological interaction where two or more species benefit.
– Mutualism is vital for terrestrial ecosystem function, with 80% of land plant species relying on mycorrhizal relationships.
– Mutualism has driven the evolution of biological diversity, such as flower forms and co-evolution between species.
– Terrestrial ecosystems heavily rely on mutualistic interactions, such as mycorrhizal relationships and seed dispersal.
– Major evolutionary events, like the evolution of eukaryotic cells and the colonization of land by plants, have been linked to mutualism.
Types of Mutualism
– Resource-Resource Relationships: In mycorrhizal associations, plants provide carbohydrates to fungi in exchange for phosphate and nitrogenous compounds. Rhizobia bacteria fix nitrogen for leguminous plants in return for energy-containing carbohydrates.
– Service-Resource Relationships: Pollination involves plants trading food resources like nectar or pollen for the service of pollen dispersal. Cleaning symbiosis occurs when phagophiles feed on ectoparasites, providing an anti-pest service. Zoochory is the dispersal of plant seeds by animals, where plants produce food resources for animals that disperse the seeds.
– Service-Service Relationships: Anemonefish and sea anemones have a mutualistic relationship where the fish provides protection from predators, and the anemonefish waste feeds the symbiotic algae in the anemone’s tentacles. Some ants protect acacia trees from herbivores and competition, while also feeding on food-bodies on the acacia plant.
Mathematical Modeling of Mutualism
– Mathematical treatments of mutualisms have lagged behind those of other types of species interactions.
– The Lotka-Volterra equations are a simple framework for modeling species interactions.
– Mutualism is represented in mathematical models as a modified logistic growth equation.
– Type I functional response refers to a linear relationship between benefit provided to species 1 and density of species 2.
– Type II functional response refers to a saturating relationship between benefit provided to species 1 and density of species 2.
Mutualism Breakdown
– Mutualisms can be lost by evolution, with one mutualist shifting to parasitism or abandoning the mutualism.
– Measuring the fitness benefit in mutualistic relationships can be challenging.
– Mutualisms can be categorized as obligate or facultative based on the closeness of the association.
– Mutualism breakdown can occur due to resource limitation, cheating or exploitation by one partner, environmental changes, loss of partner or habitat, and competition with other species.
Examples of Mutualistic Relationships
– Coral-algae mutualism: Corals provide a habitat for algae, and the algae provide photosynthetic products to the corals.
– Acacia-ant mutualism: Ants protect acacia trees from herbivores and competition, while also feeding on food-bodies on the acacia plant.
– Fig-wasp mutualism: Fig wasps pollinate figs, and the figs provide a place for the wasps to lay their eggs.
– Cleaner shrimp-fish mutualism: Cleaner shrimp remove parasites from fish, and the fish provide food for the shrimp.
– Nitrogen-fixing bacteria-legume mutualism: Bacteria fix nitrogen for leguminous plants, and the plants provide carbohydrates to the bacteria. Source: https://en.wikipedia.org/wiki/Mutualism_(biology)
