![Common clownfish curves dnsmpl](https://upload.wikimedia.org/wikipedia/commons/7/70/Common_clownfish_curves_dnsmpl.jpg)
Symbiosis (from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
, , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term
biological interaction
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species (interspecific interaction ...
between two different
biological organisms, be it
mutualistic,
commensalistic, or
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
. The organisms, each termed a symbiont, must be of different
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. In 1879,
Heinrich Anton de Bary
Heinrich Anton de Bary (26 January 183119 January 1888) was a German surgeon, botanist, microbiologist, and mycologist (fungal systematics and physiology).
He is considered a founding father of plant pathology (phytopathology) as well as the fou ...
defined it as "the living together of unlike organisms". The term was subject to a century-long debate about whether it should specifically denote mutualism, as in
lichens. Biologists have now abandoned that restriction.
Symbiosis can be obligatory, which means that one or more of the symbionts depend on each other for survival, or facultative (optional), when they can generally live independently.
Symbiosis is also classified by physical attachment. When symbionts form a single body it is called conjunctive symbiosis, while all other arrangements are called disjunctive symbiosis.
["symbiosis." Dorland's Illustrated Medical Dictionary. Philadelphia: Elsevier Health Sciences, 2007. Credo Reference. Web. 17 September 2012] When one organism lives on the surface of another, such as
head lice
The head louse (''Pediculus humanus capitis'') is an obligate ectoparasite of humans. Head lice are wingless insects that spend their entire lives on the human scalp and feeding exclusively on human blood. Humans are the only known hosts of thi ...
on humans, it is called
ectosymbiosis
Ectosymbiosis is a form of symbiotic behavior in which a parasite lives on the body surface of the host, including internal surfaces such as the lining of the digestive tube and the ducts of glands. The parasitic species is generally a ...
; when one partner lives inside the tissues of another, such as ''
Symbiodinium
: ''This is about the genus sometimes called Zoox. For the company, see Zoox (company)''
''Symbiodinium'' is a genus of dinoflagellates that encompasses the largest and most prevalent group of endosymbiotic dinoflagellates known. These unicell ...
'' within
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
, it is termed
endosymbiosis
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...
.
Definition
![Symbiotic relationships diagram](https://upload.wikimedia.org/wikipedia/commons/6/64/Symbiotic_relationships_diagram.svg)
The definition of ''symbiosis'' was a matter of debate for 130 years. In 1877,
Albert Bernhard Frank
Albert Bernhard Frank (January 17, 1839 – September 27, 1900) was a German botanist, plant pathologist, and mycologist, born in Dresden. He is credited with coining the term ''mycorrhiza'' in his 1885 paper "Über die auf Wurzelsymbiose beruhen ...
used the term ''symbiosis'' to describe the mutualistic relationship in
lichens. In 1878, the German
mycologist Heinrich Anton de Bary
Heinrich Anton de Bary (26 January 183119 January 1888) was a German surgeon, botanist, microbiologist, and mycologist (fungal systematics and physiology).
He is considered a founding father of plant pathology (phytopathology) as well as the fou ...
defined it as "the living together of unlike organisms".
The definition has varied among scientists, with some advocating that it should only refer to persistent
mutualisms, while others thought it should apply to all persistent biological interactions (in other words, to mutualism,
commensalism
Commensalism is a long-term biological interaction ( symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fr ...
, and
parasitism, but excluding brief interactions such as
predation
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
). In the 21st century, the latter has become the definition widely accepted by biologists.
In 1949,
Edward Haskell
Edward Fröhlich Haskell (August 24, 1906 – 1986) was a synergic scientist who dedicated his life to the unification of human knowledge into a single discipline. Biography
Haskell was born in Phillipopolis, now Plovdiv, Bulgaria. His mother wa ...
proposed an integrative approach with a classification of "co-actions", later adopted by biologists as "interactions".
Obligate versus facultative
Relationships can be obligate, meaning that one or both of the symbionts entirely depend on each other for survival. For example, in
lichens, which consist of fungal and photosynthetic symbionts, the fungal partners cannot live on their own.
The algal or cyanobacterial symbionts in lichens, such as ''
Trentepohlia'', can generally live independently, and their part of the relationship is therefore described as facultative (optional), or non-obligate.
Physical interaction
Endosymbiosis
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...
is any symbiotic relationship in which one symbiont lives within the tissues of the other, either within the cells or extracellularly.
Examples include diverse
microbiome
A microbiome () is the community of microorganisms that can usually be found living together in any given habitat. It was defined more precisely in 1988 by Whipps ''et al.'' as "a characteristic microbial community occupying a reasonably wel ...
s:
rhizobia,
nitrogen-fixing bacteria
Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...
that live in
root nodules on
legume roots;
actinomycete
The Actinomycetales is an order of Actinomycetota. A member of the order is often called an actinomycete. Actinomycetales are generally gram-positive and anaerobic and have mycelia in a filamentous and branching growth pattern. Some actinomycete ...
s, nitrogen-fixing bacteria such as ''
Frankia
''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the ''Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of root ...
'', which live in
alder
Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
root nodules; single-celled
algae inside reef-building
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
s; and bacterial
endosymbiont
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...
s that provide essential nutrients to about 10%–15% of insects.
Ectosymbiosis
Ectosymbiosis is a form of symbiotic behavior in which a parasite lives on the body surface of the host, including internal surfaces such as the lining of the digestive tube and the ducts of glands. The parasitic species is generally a ...
is any symbiotic relationship in which the symbiont lives on the body surface of the
host, including the inner surface of the
digestive tract or the ducts of
exocrine gland
Exocrine glands are glands that secrete substances on to an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate and mucous. Exocrine glands are one of ...
s.
Examples of this include
ectoparasites
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
such as
lice;
commensal
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
ectosymbionts such as the
barnacles
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...
, which attach themselves to the jaw of
baleen whales
Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in the ...
; and mutualist ectosymbionts such as
cleaner fish
Cleaner fish are fish that show a specialist feeding strategy by providing a service to other species, referred to as clients, by removing dead skin, ectoparasites, and infected tissue from the surface or gill chambers. This example of cleaning ...
.
Competition
Competition can be defined as an interaction between
organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s or species, in which the
fitness of one is lowered by the presence of another.
Limited supply of at least one resource (such as
food,
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
, and
territory
A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal.
In international politics, a territory is usually either the total area from which a state may extract power resources or a ...
) used by both usually facilitates this type of interaction, although the competition may also exist over other 'amenities', such as females for reproduction (in the case of male organisms of the same species).
[Begon, M., J.L. Harper and C.R. Townsend. 1996. ''Ecology: individuals, populations, and communities'', Third Edition. Blackwell Science Ltd., Cambridge, Massachusetts, USA.]
In competition, this interaction is typically seen as a lose-lose situation. Some specific interactions can be between sea sponges and coral, Jakals and small animals, and wolves and bears.
For example, one or the other could take all the nutrients avaiblable (the sea sponge), which sounds amazing for the sea sponge, but in return the coral are left with nothing. When the coral are left with nothing, they die and this throws the ecosystem out of balance. The reefs needs to coral, and without the coral, the reefs will die, along with the sea sponge whom will no longer have any nutrients from the reefs.
Are you seeing how this is a lose-lose situation? Each organisms will need each other. Again, with jakals and small animals. If there are no small animals, then the jakal have nothing to prey on, but if the jakals take all the water supply, then there will be no small animals and the cycle will continue.
Lastly, this one is a bit different. In the sense that it is not prey and predators, but instead predator and predator. If either the bears or wolves take all the prey then the other will eventually die off. Everything will be a lose-lose situation if the environment does not work perfectly. One cannot live without the other doing their job correctly and not being too greedy with their prey.
Mutualism
![Calcinus laevimanus hermit crab with Calliactis sea anemone](https://upload.wikimedia.org/wikipedia/commons/7/79/Calcinus_laevimanus_hermit_crab_with_Calliactis_sea_anemone._2_frames_in_one.jpg)
Mutualism or interspecies
reciprocal altruism
In evolutionary biology, reciprocal altruism is a behaviour whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar m ...
is a long-term relationship between individuals of different
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
where both individuals benefit.
Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both.
![Bryolith (Banc d'Arguin, Mauritania)](https://upload.wikimedia.org/wikipedia/commons/3/3a/Bryolith_%28Banc_d%27Arguin%2C_Mauritania%29.jpg)
A large percentage of
herbivores
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
have mutualistic
gut flora to help them digest plant matter, which is more difficult to digest than animal prey.
This gut flora is made up of cellulose-digesting
protozoans
Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Histo ...
or bacteria living in the herbivores' intestines.
Coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
reefs are the result of mutualism between coral organisms and various types of algae which live inside them. Most land plants and land ecosystems rely on mutualism between the plants, which
fix carbon from the air, and
mycorrhyzal fungi, which help in extracting water and minerals from the ground.
An example of mutualism is the relationship between the
ocellaris clownfish
The ocellaris clownfish (''Amphiprion ocellaris''), also known as the false percula clownfish or common clownfish, is a marine fish belonging to the family Pomacentridae, which includes clownfishes and damselfishes. ''Amphiprion ocellaris'' are ...
that dwell among the
tentacle
In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work ma ...
s of
Ritteri sea anemones. The territorial fish protects the anemone from anemone-
eating
Eating (also known as consuming) is the ingestion of food, typically to provide a heterotrophic organism with energy and to allow for growth. Animals and other heterotrophs must eat in order to survive — carnivores eat other animals, he ...
fish, and in turn the
stinging tentacles of the anemone protect the clownfish from its
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s. A special
mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...
on the clownfish protects it from the stinging tentacles.
A further example is the
goby
Goby is a common name for many species of small to medium sized ray-finned fish, normally with large heads and tapered bodies, which are found in marine, brackish and freshwater environments. Traditionally most of the species called gobies have b ...
, a fish which sometimes lives together with a
shrimp. The shrimp digs and cleans up a burrow in the sand in which both the shrimp and the goby fish live. The shrimp is almost blind, leaving it vulnerable to predators when outside its burrow. In case of danger, the goby touches the shrimp with its tail to warn it. When that happens both the shrimp and goby quickly retreat into the burrow. Different species of gobies (''
Elacatinus
''Elacatinus'' is a genus of small marine gobies, often known collectively as the neon gobies. Although only one species, ''E. oceanops'', is technically the "neon goby," because of their similar appearance, other members of the genus are genera ...
spp.'') also
clean up ectoparasites in other fish, possibly another kind of mutualism.
A facultative symbiosis is seen in encrusting
bryozoans
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...
and
hermit crabs. The bryozoan colony (''Acanthodesia commensale'') develops a cirumrotatory growth and offers the crab (''Pseudopagurus granulimanus'') a helicospiral-tubular extension of its living chamber that initially was situated within a gastropod shell.
Many types of tropical and sub-tropical ants have evolved very complex relationships with certain tree species.
Endosymbiosis
In endosymbiosis, the host cell lacks some of the nutrients which the
endosymbiont
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...
provides. As a result, the host favors endosymbiont's growth processes within itself by producing some specialized cells. These cells affect the genetic composition of the host in order to regulate the increasing population of the endosymbionts and ensure that these genetic changes are passed onto the offspring via
vertical transmission (
heredity).
A spectacular example of obligate mutualism is the relationship between the
siboglinid tube worm
A tubeworm is any worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body.
Tubeworms are found among the following taxa:
* Annelida, the ...
s and symbiotic
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
that live at
hydrothermal vents and
cold seep
A cold seep (sometimes called a cold vent) is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. ''Cold'' does not mean that the temperature of the see ...
s. The worm has no digestive tract and is wholly reliant on its internal symbionts for nutrition. The bacteria oxidize either hydrogen sulfide or methane, which the host supplies to them. These worms were discovered in the late 1980s at the hydrothermal vents near the Galapagos Islands and have since been found at
deep-sea
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
hydrothermal vents and cold seeps in all of the world's oceans.
As the endosymbiont adapts to the host's lifestyle, the endosymbiont changes dramatically. There is a drastic reduction in its
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
size, as many genes are lost during the process of
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
, and
DNA repair and recombination, while important genes participating in the DNA-to-RNA
transcription
Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including:
Genetics
* Transcription (biology), the copying of DNA into RNA, the fir ...
, protein
translation
Translation is the communication of the meaning of a source-language text by means of an equivalent target-language text. The English language draws a terminological distinction (which does not exist in every language) between ''transla ...
and DNA/RNA replication are retained. The decrease in genome size is due to loss of protein coding genes and not due to lessening of inter-genic regions or
open reading frame
In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible readin ...
(ORF) size. Species that are naturally evolving and contain reduced sizes of genes can be accounted for an increased number of noticeable differences between them, thereby leading to changes in their evolutionary rates. When endosymbiotic bacteria related with insects are passed on to the offspring strictly via vertical genetic transmission, intracellular bacteria go across many hurdles during the process, resulting in the decrease in effective population sizes, as compared to the free-living bacteria. The incapability of the endosymbiotic bacteria to reinstate their wild type
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...
via a recombination process is called ''
Muller's ratchet
In evolutionary genetics, Muller's ratchet (named after Hermann Joseph Muller, by analogy with a ratchet effect) is a process through which, in the absence of recombination (especially in an asexual population), an accumulation of irreversible d ...
'' phenomenon. Muller's ratchet phenomenon, together with less effective population sizes, leads to an accretion of deleterious
mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA replication, DNA or viral repl ...
s in the non-essential genes of the intracellular bacteria. This can be due to lack of
selection
Selection may refer to:
Science
* Selection (biology), also called natural selection, selection in evolution
** Sex selection, in genetics
** Mate selection, in mating
** Sexual selection in humans, in human sexuality
** Human mating strateg ...
mechanisms prevailing in the relatively "rich" host environment.
Commensalism
![Fly June 2008-2](https://upload.wikimedia.org/wikipedia/commons/d/d3/Fly_June_2008-2.jpg)
Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. It is derived from the English word
commensal
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
, used of human
social interaction. It derives from a medieval Latin word meaning sharing food, formed from ''com-'' (with) and ''mensa'' (table).
Commensal relationships may involve one organism using another for transportation (
phoresy
Phoresis or phoresy is a non-permanent, commensalistic interaction in which one organism (a phoront or phoretic) attaches itself to another (the host) solely for the purpose of travel. Phoresis has been observed directly in ticks and mites s ...
) or for housing (
inquilinism), or it may also involve one organism using something another created, after its death (
metabiosis). Examples of metabiosis are
hermit crab
Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an as ...
s using
gastropod shells to protect their bodies, and spiders building their webs on
plants
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude ...
.
Parasitism
![Taenia solium tapeworm scolex with its four suckers and two rows of hooks 5262 lores](https://upload.wikimedia.org/wikipedia/commons/3/36/Taenia_solium_tapeworm_scolex_with_its_four_suckers_and_two_rows_of_hooks_5262_lores.jpg)
In a
parasitic relationship, the parasite benefits while the host is harmed. Parasitism takes many forms, from
endoparasites that live within the host's body to
ectoparasites
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
and
parasitic castrators that live on its surface and
micropredators like mosquitoes that visit intermittently. Parasitism is an extremely successful mode of life; about 40% of all animal species are parasites, and the average mammal species is host to 4 nematodes, 2 cestodes, and 2 trematodes.
Mimicry
Mimicry is a form of symbiosis in which a species adopts distinct characteristics of another species to alter its relationship dynamic with the species being mimicked, to its own advantage. Among the many types of mimicry are Batesian and Müllerian, the first involving one-sided exploitation, the second providing mutual benefit.
Batesian mimicry is an exploitative three-party interaction where one species, the mimic, has evolved to mimic another, the model, to
deceive
Deception or falsehood is an act or statement that misleads, hides the truth, or promotes a belief, concept, or idea that is not true. It is often done for personal gain or advantage. Deception can involve dissimulation, propaganda and sleight ...
a third, the dupe. In terms of
signalling theory
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species. The central question is when organisms with conflicting interests, such as in se ...
, the mimic and model have evolved to send a signal; the dupe has evolved to receive it from the model. This is to the advantage of the mimic but to the detriment of both the model, whose protective signals are effectively weakened, and of the dupe, which is deprived of an edible prey. For example, a wasp is a strongly-defended model, which signals with its conspicuous black and yellow coloration that it is an unprofitable prey to predators such as birds which hunt by sight; many hoverflies are Batesian mimics of wasps, and any bird that avoids these hoverflies is a dupe.
[; Reprint: ] In contrast,
Müllerian mimicry
Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimic each other's honest warning signals, to their mutual benefit. The benefit to Mülleria ...
is mutually beneficial as all participants are both models and mimics. For example, different species of
bumblebee
A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related genera ...
mimic each other, with similar warning coloration in combinations of black, white, red, and yellow, and all of them benefit from the relationship.
Amensalism
![Black Walnut middle](https://upload.wikimedia.org/wikipedia/commons/5/54/Black_Walnut_middle.JPG)
Amensalism is a non-symbiotic, asymmetric interaction where one species is harmed or killed by the other, and one is unaffected by the other.
There are two types of amensalism, competition and
antagonism (or antibiosis). Competition is where a larger or stronger organism deprives a smaller or weaker one of a resource. Antagonism occurs when one organism is damaged or killed by another through a chemical secretion. An example of competition is a sapling growing under the shadow of a mature tree. The mature tree can rob the
sapling
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
of necessary sunlight and, if the mature tree is very large, it can take up rainwater and deplete soil nutrients. Throughout the process, the mature tree is unaffected by the sapling. Indeed, if the sapling dies, the mature tree gains nutrients from the decaying sapling. An example of antagonism is ''
Juglans nigra
''Juglans nigra'', the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south ...
'' (black walnut), secreting
juglone
Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is an organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble i ...
, a substance which destroys many herbaceous plants within its root zone.
Amensalism is often used to describe strongly asymmetrical competitive interactions, such as between the
Spanish ibex
The Iberian ibex (''Capra pyrenaica''), also known as the Spanish ibex, Spanish wild goat, or Iberian wild goat, is a species of ibex endemic to the Iberian Peninsula. Four subspecies have been described; two are now extinct. The Portuguese subs ...
and
weevil
Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, ...
s of the genus ''
Timarcha'' which feed upon the same type of shrub. Whilst the presence of the weevil has almost no influence on food availability, the presence of ibex has an enormous detrimental effect on weevil numbers, as they consume significant quantities of plant matter and incidentally ingest the weevils upon it.
Cleaning symbiosis
Cleaning symbiosis is an association between individuals of two species, where one (the cleaner) removes and eats parasites and other materials from the surface of the other (the client). It is putatively mutually beneficial, but biologists have long debated whether it is mutual selfishness, or simply exploitative. Cleaning symbiosis is well known among marine fish, where some small species of
cleaner fish
Cleaner fish are fish that show a specialist feeding strategy by providing a service to other species, referred to as clients, by removing dead skin, ectoparasites, and infected tissue from the surface or gill chambers. This example of cleaning ...
, notably
wrasse
The wrasses are a family, Labridae, of marine fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into 9 subgroups or tribes.
They are typically small, most of them le ...
s but also species in other genera, are specialised to feed almost exclusively by cleaning larger fish and other marine animals.
Co-evolution and the Hologenome Theory
![Common jassid nymphs and ants02](https://upload.wikimedia.org/wikipedia/commons/a/a5/Common_jassid_nymphs_and_ants02.jpg)
Symbiosis is increasingly recognized as an important selective force behind evolution;
many species have a long history of interdependent
co-evolution
In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well ...
.
Although symbiosis was once discounted as an anecdotal evolutionary phenomenon, evidence is now overwhelming that obligate or facultative associations among microorganisms and between microorganisms and multicellular hosts had crucial consequences in many landmark events in evolution and in the generation of phenotypic diversity and complex phenotypes able to colonise new environments.
[ ]
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Hologenome Development and Evolution
Evolution originated from changes in development where variations within species are selected for or against because of the symbionts involved.
The Hologenome theory relates to the holobiont and symbionts genome together as a whole. Microbes live everywhere in and on every multicellular organism. Many organisms rely on their symbionts in order to develop properly, this is known as co-development. In cases of co-development the symbionts send signals to their host which determine developmental processes. Co-development is commonly seen in both arthropods and vertebrates.
Symbiogenesis
One hypothesis for the origin of the nucleus in
eukaryotes (plants, animals, fungi, and
protists) is that it developed from a
symbiogenesis
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory,) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. The theory holds that mitochondria, plastids such as chloroplasts, and pos ...
between bacteria and archaea.
It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. Evidence for this includes the fact that
mitochondria and
chloroplasts divide independently of the cell, and that these organelles have their own genome.
The biologist
Lynn Margulis
Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American evolutionary biologist, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Ma ...
, famous for her work on
endosymbiosis
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship.
(The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...
, contended that symbiosis is a major driving force behind
evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
. She considered
Darwin's notion of evolution, driven by competition, to be incomplete and claimed that evolution is strongly based on
co-operation
Cooperation (written as co-operation in British English) is the process of groups of organisms working or acting together for common, mutual, or some underlying benefit, as opposed to working in competition for selfish benefit. Many animal a ...
,
interaction
Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to:
Science
* Interaction hypothesis, a theory of second language acquisition
* Interaction (statistics)
* Interactions o ...
, and
mutual dependence among organisms. According to Margulis and her son
Dorion Sagan, "
Life
Life is a quality that distinguishes matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes, from that which does not, and is defined by the capacity for Cell growth, growth, reaction to Stimu ...
did not take over the
globe
A globe is a spherical model of Earth, of some other celestial body, or of the celestial sphere. Globes serve purposes similar to maps, but unlike maps, they do not distort the surface that they portray except to scale it down. A model glo ...
by
combat, but by
networking."
Co-evolutionary relationships
Mycorrhizas
About 80% of
vascular plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
worldwide form symbiotic relationships with fungi, in particular in
arbuscular mycorrhiza
An arbuscular mycorrhiza (AM) (plural ''mycorrhizae'', a.k.a. ''endomycorrhiza'') is a type of mycorrhiza in which the symbiont fungus (''AM fungi'', or AMF) penetrates the cortical cells of the roots of a vascular plant forming arbuscules. ( ...
s.
Pollination
Flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s and the animals that
pollinate
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...
them have co-evolved. Many plants that are pollinated by
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
s (in
entomophily
Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, som ...
),
bat
Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...
s, or
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s (in
ornithophily
Ornithophily or bird pollination is the pollination of flowering plants by birds. This sometimes (but not always) coevolutionary association is derived from insect pollination (entomophily) and is particularly well developed in some parts of the w ...
) have highly specialized flowers modified to promote pollination by a specific pollinator that is correspondingly adapted. The first flowering plants in the fossil record had relatively simple flowers. Adaptive
speciation quickly gave rise to many diverse groups of plants, and, at the same time, corresponding speciation occurred in certain insect groups. Some groups of plants developed nectar and large sticky pollen, while insects evolved more specialized morphologies to access and collect these rich food sources. In some taxa of plants and insects, the relationship has become dependent, where the plant species can only be pollinated by one species of insect.
Acacia ants and acacias
The
acacia ant (''Pseudomyrmex ferruginea'') is an obligate plant ant that protects at least five species of "Acacia" (''
Vachellia
''Vachellia'' is a genus of flowering plants in the legume family, Fabaceae, commonly known as thorn trees or acacias. It belongs to the subfamily Mimosoideae. Its species were considered members of genus '' Acacia'' until 2009. ''Vachellia'' ...
'') from preying insects and from other plants competing for sunlight, and the tree provides nourishment and shelter for the ant and its larvae.
Seed dispersal
Seed dispersal is the movement, spread or transport of
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s away from the parent plant. Plants have limited mobility and rely upon a variety of
dispersal vector
A dispersal vector is an agent of biological dispersal that moves a dispersal unit, or organism, away from its birth population to another location or population in which the individual will reproduce. These dispersal units can range from pollen t ...
s to transport their propagules, including both
abiotic
In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them under ...
vectors such as the wind and living (
biotic) vectors like birds. In order to attract animals, these plants evolved a set of morphological characters such as
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
colour, mass, and persistence correlated to particular seed dispersal agents. For example, plants may evolve conspicuous fruit colours to attract avian frugivores, and birds may learn to associate such colours with a food resource.
Business relationships
In a sense derived from its biological meaning, "symbiosis" can also refer to mutually beneficial business relationships,
[Sagarin, R.]
To Overcome Your Company’s Limits, Look to Symbiosis
''Harvard Business Review'', published 25 June 2013, accessed 27 April 2022 for example where a manufacturer of products for sale ensures that its distributors are adequately stocked with supplies to meet anticipated demand.
See also
Notes
References
Bibliography
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External links
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TED-Education videoSymbiosis: a surprising tale of species cooperation
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Ecology