mutualism

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Related to Mutualisms: Symbiotic Relationships

Mutualism

An interaction between two species that benefits both. Individualsthat interact with mutualists experience higher sucess than those that do not.Hence, behaving mutualistically is advantageous to the individual, and it doesnot require any concern for the well-being of the partner. At one time,mutualisms were thought to be rare curiosities primarily of interest to naturalhistorians. However, it is now believed that every species is involved in oneor more mutualisms. Mutualisms are thought to lie at the root of phenomena asdiverse as the origin of the eukaryotic cell, the diversification of floweringplants, and the pattern of elevated species diversity in tropical forests.

Mutualisms generally involve an exchange of substances or services thatorganisms would find difficult or impossible to obtain for themselves. Forinstance, Rhizobium bacteria found in nodules on the roots of manylegume (bean) species fix atmospheric nitrogen into a form (NH3)that can be taken up by plants. The plant provides the bacteria with carbon inthe form of dicarboxylic acids. The carbon is utilized by the bacteria asenergy for nitrogen fixation. Consequently, leguminous plants often thrive innitrogen-poor environments where other plants cannot persist. Anotherwell-known example is lichens, in which fungi take up carbon fixed duringphotosynthesis of their algae associates.

A second benefit offered within some mutualisms is transportation. Prominentamong these mutualisms is biotic pollination, in which certain animals visitflowers to obtain resources and return a benefit by transporting pollen betweenthe flowers they visit. A final benefit is protection from one's enemies.For example, ants attack the predators and parasites of certain aphids inexchange for access to the aphids' carbohydrate-rich excretions(honeydew).

Another consideration about mutualisms is whether they are symbiotic. Twospecies found in intimate physical association for most or all of theirlifetimes are considered to be in symbiosis. Not all symbioses are mutualistic;symbioses may benefit both, one, or neither of the partners.

Mutualisms can also be characterized as obligate or facultative (dependingon whether or not the partners can survive without each other), and asspecialized or generalized (depending on how many species can confer thebenefit in question).

Two features are common to most mutualisms. First, mutualisms are highlyvariable in time and space. Second, mutualisms are susceptible to cheating.Cheaters can be individuals of the mutualist species that profit from theirpartners' actions without offering anything in return, or else otherspecies that invade the mutualism for their own gain.

Mutualism has considerable practical significance. Certain mutualisms playcentral roles in humans' ability to feed the growing population. It hasbeen estimated that half the food consumed is the product of bioticpollination. See Ecology, Plant pathology

mutualism

[′myü·chə·wə‚liz·əm]
(ecology)
Mutual interactions between two species that are beneficial to both species.
References in periodicals archive ?
The time in observing each plant was between 2 to several minutes and it was facilitated because mutualism was given only on the basal leaves of the gamagrass on a leaf segment no longer than 5 cm.
Trees aLso can benefit from the voracious appetites of ground-dwelling predatory ants--another indirect mutualism between trees and ants.
They also found weather a mutualism survives can depend upon the density and distribution of other species in the community.
Specialization for this mutualism involves plants producing small seeds that have a fat-rich aril (elaiosome).
Parasites of mutualisms constitute a cost to both parties.
Although not closely related botanically, the Asian trees and the yuccas face similar risks in their mutualisms and have converged on similar punishments.
Many introduced plant species have been shown to rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive (Richardson et al.
Mutualisms, for example, may not be perfectly "egalitarian"; a fluctuating asymmetry in the provision of benefits is probably typical.
In the second topic, the maintenance of mutualistic associations will be studied in a so-called open nursery pollination system, where plant-pollinator associations can vary between mutualisms and antagonism.
Other creatures also form mutualisms, the term used for symbiotic living arrangements that benefit both partners.
My project will improve our understanding of mutualisms by unravelling the metabolic and behavioural mechanisms underlying species interdependence in this specialised symbiotic network.
Aside from grass studies, he says, "there has been very little evidence of defensive mutualisms between fungi and plants.