Mutualism: Definition, Meaning, Types, Examples, Facts, Topics

Mutualism definition: Mutualism is a type of ecological interaction where two different species live closely together and both benefit from the relationship. Each organism provides resources or services that help the other survive, grow, or reproduce. Examples include bees pollinating flowers while collecting nectar, and certain bacteria in the human gut aiding digestion. In this article, what is mutualism, the types of mutualism, and the mechanism of mutualism are discussed. Mutualism is a topic of the chapter Organism and Population in Biology.

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1. What is Mutualism?
2. Types of Mutualism
3. Mechanisms of Mutualism

What is Mutualism?

Mutualism is one of the most elemental ideas in ecology that pertains to a kind of symbiosis in which both species involved benefit the other in some way. The organism within mutualistic interaction engages in an activity that will increase the other’s chances of survival, growth or reproduction hence promoting a symbiotic relationship for both the species. There are numerous examples from the nature systems; one of them is the mutualism between flowers and bees where flowers offer nectar and pollen to the bees as their food, and at the same time the bees help flowers in their pollination process by transferring pollen from one plant to another.

Reciprocal associations play an outstanding role in the processes shaping the structure of ecosystems and affect the overall level of biodiversity. These aspects include aiding in the coexistence of other species, aiding in nutrient cycling, and even making an ecosystem more resilient to change, which makes these organisms huge factors in the health of ecosystems across the globe.

Types of Mutualism

The types of mutualism are listed below-

Obligate Mutualism

Obligate mutualism relates to a situation whereby both species are wholly dependent on each other and are unable to survive the reproductive process without the other. The lack of one of them means that neither of the species can reproduce which will ultimately lead to its extinction. This is mostly a specific and close relationship where co-development is seen to be playing a major role in the sustenance of the dependency.

Examples

• Coral and Zooxanthellae: This is a partner because coral polyps depend on the zooxanthellae algae for essential nutrients which are derived from photosynthesis and in return the zooxanthellae algae rely on the coral polyps for shelter as well as nutrients.

• Termites and Gut Protozoa: Termites are in turn helped by protozoa to break down cellulose from wood; on its part, the protozoa benefit from a stable environment and food source from the termite’s digestive system.

Facultative Mutualism

It refers to the modification of existing resources to produce a reciprocal interaction that is not obligatory among the species. Although both partner species gain something from the other’s company, each is capable of living and reproducing on its own if pushed to it. The relationship can often be less formal and can fluctuate for a period depending on certain factors of the environment.

Examples

• Pollination by Bees: Flowers get pollinated by bees through the movement of pollen from one plant to another to get the nectar which is the food of bees. Bees and flowering plants do rely on each other but this mutualism is not obligate as the bees do not need to go and buzz on flowers to survive.

• Seed Dispersal by Birds: Much of the plants, and fruits therefore provide a meal source to the birds which in turn provide natural reproductive means to plants as they release seeds in their droppings.

Trophic

This is a mutualistic association in which one species directly supplies another with a trophy or energy.

Defensive

This type of mutualism is one where one partner receives protection, defence or security from a predator or pathogen from the other partner.

Dispersive

Dispersive mutualism describes a situation where the parties involved exhibit mutualism where one of the parties helps enhance the dispersion of propagules of the other party’s offspring.

Also Read-

• MCQ on Mutualism
• Organism and Population
• Biotic Factors
• Abiotic Factors

Mechanisms of Mutualism

The mechanism of mutualism is described below-

Nutrient Exchange

Mycorrhizal Fungi And Plants

The mycorrhizal fungi are beneficial in forming symbiotic partnerships with the plants, especially trees in which they penetrate their root systems. The fungi increase the efficiency of water and nutrient uptake from the soil including phosphorous and nitrogen. In exchange, the fungi provide organic compounds, especially sugars and carbohydrates synthesized by the plant through photosynthesis.

Rhizobia Bacteria And Legumes

Rhizobia bacteria fixing nitrogen in soil connect with leguminous plants (including peas, beans and clovers) and form nodules on the roots of these plants. Inside these nodules, the bacteria known as Rhizobia fix the nitrogen from the air in the form of plant-usable nitrogen, specifically, ammonium. The plants offer the bacteria carbohydrates with which they feed, to carry out their activities effectively.

Protection Mutualism

Ants And Acacia Trees

Some types of ants exhibit what is called protective mutualism with acacia trees. In return, the ants reside in hollow thorns or other structures built by the acacia tree and the tree is safeguarded by ants whose main ability is to threaten or attack any herbivore that attempts to feed on the tree. In turn, the Acacia tree offers the ants protection and food in the form of organs referred to as Extrafloral nectary or Beltian bodies, which are nutrient-producing structures.

Cleaner Fish And Their Hosts

Cleaner fish including cleaner wrasses and cleaner shrimp get involved in non-aggressive cleaning associations with other large fishes or other sea creatures. They feed on ectoparasites, skin and gill mucus, and consume dead tissue, and algae with the host’s skin or gill surface since cleaning has a positive impact on the host as well as reduces the chances of being infected.

Reproductive Mutualism

Pollination mechanisms

Pollination is on behalf of the flowering plants and the pollinators (for instance, bees, butterflies, birds and the like). These are insects or types of animals that carry pollen from one flower to another to help in the process of pollination, which helps plants produce seeds. Consequently, pollinators are given nectar or pollen in exchange for them.

Seed Dispersal Methods

Some plants, for instance, depend on animals to disperse their seeds from one location to another; birds, mammals, insects, and others. Seeds are then eaten by animals and then defecated or relocated to other areas by the animals. This mutualism is beneficial in that it assists plants in finding and taking over new territories to propagate in.

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