L1++Mutualism

Mutualism: A positive reciprocal relationship between two individuals of different species, which results in increased fitness for both parties.

Obligate mutualisms: When two species are permanent pairing in which one or both species cannot live independently.

Examples of obligate mutualisms: Lichen Corals Dinoflagellate algae Fungus-farming ants Cleaner fish and ‘customer’ fish- cleaner removes parasites and dead skin from the customer fish and the customer fish provides food for the cleaner fish. When cleaner fishes were removed from the reefs in the Bahamas, there was an outbreak of skin disease and increased mortalities.

Facultative Mutualisms: Where the partners may coexist without a reliance on each other and are only mutualists opportunistically. The species that are interacting are often different species creating a diffuse relationship. In this relationship, the species interact, but do not attach at the hip.

Pollination: To exchange genes with the rest of the populations, an outcrossing plant needs to transfer its pollen to the stigma of a conspecific plant, and receive pollen from a conspecific. Pollination occurs when an outcrossing plant exchanges its pollen with the stigma of a conspecific plant. Wind-pollination or help from any pollinator species such as insects, birds, bats or small mammals can accomplish this exchange. These pollinators are used to transfer the pollen from plant to plant. They benefit from the relationship by receiving nectar, oil or pollen as a food source. There are many plants and animals that are fully dependent on this symbiotic relationship such as the yucca cacti and yucca moths or fig trees and fig wasps. In the case of the male Euglossine bees, the pollen received is transformed into sex pheromones.

Seed Dispersal: Some very small seeds can be dispersed in the air, but many larger seeds require water currents or animal assistance from dispersal. Some important seed dispersers include rodents, bats, birds and ants. Some of these dispersers are seed predators. These animals consume the seeds and aid dispersal by dropping, storing or losing some of the seeds. While the seed lose in accidental, it helps to feed the mutually beneficial relationship. Defensive Mutualism: One partner in the relationship works to defend the other from predators or competitors. Ant-plant mutualisms are very common. These occur because the plants provide the ants with a source from specialized glazed which are called extrafloral nectarines. These nectars secrete protein and sugar rich fluid. Sometimes the plants can even act as a protective home for the ants.

Symbiotic Mutualists Within Animal Tissues and Cells: Mutualists can sometimes reside inside the guts or cells in animal partners. Animals such as deer and cattle possess a multi-chambered stomach in which bacterial and protozoan fermentation takes place. One example of this relationship is termites. In the termites there are necessary breakdown enzymes called cellulases, which live in specialized gut structures and this helps breakdown their diet of wood.

Mutualism and Evolution: The evolution of mutualism most likely started from the parasite host relationships or the predator-prey relationships and evolved from there. One example of this is insect pollination. This relationship most likely started due to the pollen being stolen by the insects from the wind-pollinating flowers. As the two species evolved, they came to depend on each other as they both benefited from the relationship. Therefore, as the flowers evolved they began to have brighter colors, scents and nectars that all helped to attract the insects. Mutualistic relationships can also deteriorate into an unbalanced exploitation of one of the partners called parasitism.