In a symbiotic mutualism, the clownfish feeds on small invertebrates that otherwise have potential to harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone's stinging cells, to which the clownfish is immune.

Symbiosis (from Ancient Greek σύν "together" and βίωσις "living")^[1] is close and often long-term interaction between different biological species. In 1877, Bennett used the word symbiosis (which previously had been used of people living together in community) to describe the mutualistic relationship in lichens.^[2] In 1879, by the German mycologist Heinrich Anton de Bary, defined it as "the living together of unlike organisms."^[3][4]

The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any types of persistent biological interactions (i.e. mutualistic, commensalistic, or parasitic).^[5]

Some symbiotic relationships are obligate, meaning that both symbionts entirely depend on each other for survival. For example, many lichens consist of fungal and photosynthetic symbionts that cannot live on their own.^[3][6][7][8] Others are facultative, meaning that they can, but do not have to live with the other organism.

Symbiotic relationships include those associations in which one organism lives on another (ectosymbiosis, such as mistletoe), or where one partner lives inside the other (endosymbiosis, such as lactobacilli and other bacteria in humans or zooxanthelles in corals).^[9][10]

Physical interaction[link]

Alder tree root nodule

Endosymbiosis is any symbiotic relationship in which one symbiont lives within the tissues of the other, either in the intracellular space or extracellularly.^[10][11] Examples include diverse microbiomes, rhizobia, nitrogen-fixing bacteria that live in root nodules on legume roots; actinomycete nitrogen-fixing bacteria called Frankia, which live in alder tree root nodules; single-celled algae inside reef-building corals; and bacterial endosymbionts that provide essential nutrients to about 10%–15% of insects.

Ectosymbiosis, also referred to as exosymbiosis, 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 glands.^[10][12] Examples of this include ectoparasites such as lice, commensal ectosymbionts such as the barnacles that attach themselves to the jaw of baleen whales, and mutualist ectosymbionts such as cleaner fish.

Mutualism[link]

Hermit crab, Calcinus laevimanus, with sea anemone.

Mutualism is any relationship between individuals of different species where both individuals derive a benefit.^[13] In general, only lifelong interactions involving close physical and biochemical contact can properly be considered symbiotic. Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both. Many biologists restrict the definition of symbiosis to close mutualist relationships.

A large percentage of herbivores have mutualistic gut fauna that help them digest plant matter, which is more difficult to digest than animal prey.^[9] Coral reefs are the result of mutualisms between coral organisms and various types of algae that live inside them.^[14] Most land plants and land ecosystems rely on mutualisms between the plants, which fix carbon from the air, and mycorrhyzal fungi, which help in extracting minerals from the ground.^[15]

An example of mutual symbiosis is the relationship between the ocellaris clownfish that dwell among the tentacles of Ritteri sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfish from its predators. A special mucus on the clownfish protects it from the stinging tentacles.^[16]

Another example is the goby 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 above ground. In case of danger the goby fish touches the shrimp with its tail to warn it. When that happens both the shrimp and goby fish quickly retreat into the burrow.^[17]

One of the most spectacular examples of obligate mutualism is between the siboglinid tube worms and symbiotic bacteria that live at hydrothermal vents and cold seeps. 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 hydrothermal vents and cold seeps in all of the world's oceans.^[18]

There are also many types of tropical and sub-tropical ants that have evolved very complex relationships with certain tree species.^[19]

Mutualism and endosymbiosis[link]

During mutualistic symbioses, the host cell lacks some of the nutrients, which are provided by the endosymbiont. 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 ensuring that these genetic changes are passed onto the offspring via vertical transmission (heredity).^[20]

Adaptation of the endosymbiont to the host’s lifestyle leads to many changes in the endosymbiont – the foremost being drastic reduction in its genome size. This is due to many genes being lost during the process of metabolism, and DNA repair and recombination. While important genes participating in the DNA to RNA transcription, protein translation and DNA/RNA replication are retained. That is, a 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 (ORF) size. Thus, 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. As the endosymbiotic bacteria related with these insects are passed on to the offspring strictly via vertical genetic transmission, intracellular bacteria goes through many hurdles during the process, resulting in the decrease in effective population sizes when compared to the free living bacteria. This incapability of the endosymbiotic bacteria to reinstate its wild type phenotype via a recombination process is called as Muller’s ratchet phenomenon. Muller’s ratchet phenomenon together with less effective population sizes has led to an accretion of deleterious mutations in the non-essential genes of the intracellular bacteria.^[21] This could have been due to lack of selection mechanisms prevailing in the rich environment of the host.^[22][23]

Commensalism[link]

Phoretic mites on a fly (Pseudolynchia canariensis).

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 used of human social interaction. The word derives from the medieval Latin word, formed from com- and mensa, meaning "sharing a table".^[13][24]

Commensal relationships may involve one organism using another for transportation (phoresy) or for housing (inquilinism), or it may also involve one organism using something another created, after its death (metabiosis). Examples of metabiosis are hermit crabs using gastropod shells to protect their bodies and spiders building their webs on plants.

Parasitism[link]

Flea bites on a human is an example of parasitism.

A parasitic relationship is one in which one member of the association benefits while the other is harmed.^[25] Parasitic symbioses take many forms, from endoparasites that live within the host's body to ectoparasites that live on its surface. In addition, parasites may be necrotrophic, which is to say they kill their host, or biotrophic, meaning they rely on their host's surviving. Biotrophic parasitism is an extremely successful mode of life. Depending on the definition used, as many as half of all animals have at least one parasitic phase in their life cycles, and it is also frequent in plants and fungi. Moreover, almost all free-living animals are host to one or more parasite taxa. An example of a biotrophic relationship would be a tick feeding on the blood of its host.

Amensalism[link]

Amensalism is the type of relationship that exists where one species is inhibited or completely obliterated and one is unaffected. This type of symbiosis is relatively uncommon in rudimentary reference texts, but is omnipresent in the natural world. An example is a sapling growing under the shadow of a mature tree. The mature tree can begin to rob the sapling 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. Indeed, if the sapling dies, the mature tree gains nutrients from the decaying sapling. Note that these nutrients become available because of the sapling's decomposition, rather than from the living sapling, which would be a case of parasitism.

Symbiosis and evolution[link]

Leafhoppers protected by an army of meat ants

While historically, symbiosis has received less attention than other interactions such as predation or competition,^[26] it is increasingly recognized as an important selective force behind evolution,^[9][27] with many species having a long history of interdependent co-evolution.^[28] In fact, the evolution of all eukaryotes (plants, animals, fungi, and protists) is believed under the endosymbiotic theory to have resulted from a symbiosis between various sorts of bacteria.^[9][29][30]

Vascular plants[link]

About 80% of vascular plants worldwide form symbiotic relationships with fungi, for example, in arbuscular mycorrhizas.^[31]

Symbiogenesis[link]

The biologist Lynn Margulis, famous for her work on endosymbiosis, contends that symbiosis is a major driving force behind evolution. She considers Darwin's notion of evolution, driven by competition, to be incomplete and claims that evolution is strongly based on co-operation, interaction, and mutual dependence among organisms. According to Margulis and Dorion Sagan, "Life did not take over the globe by combat, but by networking."^[32]

Co-evolution[link]

Symbiosis played a major role in the co-evolution of flowering plants and the animals that pollinate them. Many plants that are pollinated by insects, bats, or birds have highly specialized flowers modified to promote pollination by a specific pollinator that is also 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,^[33] where the plant species can only be pollinated by one species of insect.^[34]

Notes[link]

See also[link]

• Anagenesis
• Aposymbiotic
• Aquaponics
• Cheating (biology)
• Cleaning symbiosis
• Decompiculture
• Human Microbiome Project
• List of symbiotic organisms
• List of symbiotic relationships
• Microbiome
• Multigenomic organism
• Symbiogenesis
• Symbiosis (chemical)

References[link]

External links[link]

• TED-Education video - Symbiosis: a surprising tale of species cooperation.

Wikimedia Commons has media related to: Symbiosis

Look up symbiosis in Wiktionary, the free dictionary.

Living Sacrifice is a Christian heavy metal band that formed in September 1989 in Little Rock, Arkansas, United States. The band has released seven studio albums, out of which the first three were recorded under R.E.X. Records with their original vocalist Darren Johnson as a more thrash metal and death metal oriented band. The band evolved into a metalcore style beginning with Reborn (1997) under Solid State Records with the original guitarist Bruce Fitzhugh on vocals. In sound they became similar to, but still distinct from Sepultura, while others have made comparisons to early Meshuggah. In 2003 the group split up, and later their label, Solidstate, released their best-of album, In Memoriam (2005). In 2008 Living Sacrifice reformed and released a two-song digital only single called "Death Machine". They then began working on The Infinite Order which was released on January 26, 2010.

Biography[link]

Early[link]

Living Sacrifice was one of the first Christian death metal bands. The band, whose name is derived from Romans 12:1, formed in 1989 by Darren "D.J." Johnson (bass/vocals), Bruce Fitzhugh (guitar) and Lance Garvin (drums). Later Jason Truby joined in on guitar. They recorded a demo, Not Yielding to Ungodly, which got into the hands of Kurt Bachman and Joey Daub of the band Believer, who signed the band to R.E.X. records.

1990s[link]

In 1991, Living Sacrifice's self-titled debut was released on R.E.X. Records. The album received much comparison to thrash metal groups of the time, especially Slayer. In 1992, Living Sacrifice released their second album, Nonexistent. In this album, Living Sacrifice switched from Thrash metal to down-tuned death metal, and D.J. started experimenting with a death growl in his vocal approach. The members have said that they were disappointed with the experience of making this album and that the producer was to blame.

In 1994, the band released a third album, Inhabit, which is considered by some to be the heaviest of all Living Sacrifice albums.^{[citation needed]} On Inhabit, D.J. returned to a more Thrash-oriented vocal approach, deeper and lower in tone than his vocals on the band's debut. After this recording R.E.X. went bankrupt, and Living Sacrifice signed onto Solid State Records seeking to widen their audience.^[4]

After this, D.J. left the band and Bruce took over vocals.^[4] Jason's brother, Chris, also joined on bass. With this new lineup, Living Sacrifice recorded Reborn, their Solid State debut, in 1997. The band started to play a mix of groove metal and metalcore.^[5] Reborn is considered the most influential of all Living Sacrifice records and earned them a larger non-Christian fanbase. After this record, Chris and Jason left the band and Jay Stacy filled in on bass, but was later replaced by Arthur Green, formerly of Eso-Charis. Cory Brandan played guitar for a tour through Norway and Sweden but was then replaced by Rocky Gray (who would go on to play drums in Evanescence and We Are the Fallen and guitar in Soul Embraced.)

At the end of 1999, Matt Putman joined Living Sacrifice as a percussionist.

2000s[link]

In 2000, Living Sacrifice recorded their fifth full length album, The Hammering Process, with a more rhythmical sound—more oriented towards groove metal. Bruce also sang in one Evanescence song, "Lies".

In 2001, A Tribute to Living Sacrifice was released. The album contains covers of many Living Sacrifice songs by other metal bands and former members, and a Living Sacrifice song from a split album called Metamorphosis, released in 1993.

In 2002, Living Sacrifice entered the studio again, resulting in the album Conceived In Fire. In 2003, Living Sacrifice cancelled the rest of one of their tours and announced that Living Sacrifice was disbanding. Each of the band members had other duties that had to be committed to and felt it was time to move on.

In March 2005, In Memoriam was released by Solid State Records. It is a "best of" album, containing three "newly written and recorded songs by Lance Garvin, Rocky Gray and Bruce Fitzhugh", two songs from each Living Sacrifice album, plus "Enthroned," a 1998 cover of a song originally released on 1992's Nonexistent. The three new songs are "In Christ", "Killers", and "The Power of God".

In 2007, Bruce Fitzhugh was featured on the song "Sixteen", on Demon Hunter's fourth album Storm The Gates Of Hell.

On February 4, 2008, a newly created official MySpace page was updated to announce the reformation of the band. They also announced their support of Demon Hunter in the "Stronger Than Hell" tour from May 26 through July 5, 2008. On June 10, 2008, Living Sacrifice released a two-song online only sampler called "Death Machine" which can be purchased at their Myspace page, amazonmp3, and iTunes. On the same day at the Dallas, Texas date of the "Stronger Than Hell" tour, Bruce Fitzhugh announced that the band is working on a new CD which they hoped to release in 2009. The album release was delayed by Solidstate and eventually came out on January 26, 2010. A music video for their lead single off "The Infinite Order," "Rules of Engagement" was aired December 22.^[6]

2010-Present[link]

The band's seventh studio album, "The Infinite Order," was released January 26, 2010 via Solid State Records. The release was followed by a headlining tour in February, with support from War of Ages, Shai Hulud, Lionheart, and The Great Commission. Due to some circumstances, guitarist Rocky Gray was unable to perform the tour dates and was filled in by a friend of the band. However, Rocky Gray currently remains a permanent band member of Living Sacrifice. They headlined Solid State's "A Very Metal Christmas Tour" with support from Becoming the Archetype, The Famine, To Speak of Wolves, and As They Sleep in December 2010. On March 19, 2011, Living Sacrifice announced on Facebook that they were in Little Rock writing some new tunes.^[7]

Discography[link]

Studio Albums[link]

Other Releases[link]

• Not Yielding To Ungodly (Demo, 1989)
• In Memoriam (Best Of/Compilation, 2005)
• Death Machine (Digital-only EP, 2008)
• In Finite Live (DVD, 2011)^[8]

Band members[link]

Current members

• Bruce Fitzhugh - Guitar (1989–2003, 2005, and 2008–present), Lead Vocals (1997–Present)
• Rocky Gray - Guitar, Vocals (1999–2003, 2005, and 2008–present)
• Arthur Green - Bass, Vocals (1999–2003, and 2008–present)
• Lance Garvin - Drums (1989–2003, 2005, and 2008–present)

Past members

• Matt Putman - Auxiliary Percussion, Vocals (1999–2003)
• Darren Johnson - Lead Vocals, Bass (1989–1995)
• Jason Truby - Guitar (1989–1998)
• Cory Brandan Putman - Vocals, Guitar (1998)
• Chris Truby - Bass (1995–1998)
• Jay Stacy - Bass (1998–1999)

Timeline

  id:drums                          value:yellow        legend:Drums
  id:bass                           value:green         legend:Bass guitar
  id:guitar                         value:blue          legend:Lead guitar
  id:guitar2;vocals                 value:red           legend:Rhythm guitar, lead vocals
  id:percussion                     value:orange         legend:Auxiliary percussion, vocals
  id:lines                          value:black         legend:Studio albums

 at:01/01/1991 color:black layer:back
 at:01/01/1992 color:black layer:back
 at:01/01/1994 color:black layer:back
 at:06/03/1997 color:black layer:back
 at:10/26/2000 color:black layer:back
 at:09/12/2002 color:black layer:back
 at:01/26/2010 color:black layer:back

 bar:Fitzhugh text:"Bruce Fitzhugh"
 bar:Garvin text:"Lance Garvin"
 bar:Johnson text:"Darren Johnson"
 bar:Jtruby text:"Jason Truby"
 bar:Ctruby text:"Chris Truby"
 bar:Stacy text:"Jay Stacy"
 bar:CPutman text:"Cory Brandan Putman"
 bar:MPutman text:"Matt Putman"
 bar:Green text:"Arthur Green"
 bar:Gray text:"Rocky Gray"

 width:10 textcolor:black align:left anchor:from shift:(10,-4)
 bar:Fitzhugh   from:01/01/1989 till:01/01/2003 color:guitar2;vocals
 bar:Fitzhugh   from:02/04/2008 till:end        color:guitar2;vocals
 bar:Garvin     from:01/01/1989 till:01/01/2003 color:drums
 bar:Garvin     from:02/04/2008 till:end        color:drums
 bar:Johnson    from:01/01/1989 till:01/01/1995 color:bass
 bar:Jtruby     from:01/01/1989 till:01/01/1998 color:guitar
 bar:Ctruby     from:01/01/1995 till:01/01/1998 color:bass
 bar:Stacy      from:01/01/1998 till:01/01/1999 color:bass
 bar:CPutman    from:01/01/1998 till:07/01/1998 color:guitar
 bar:Gray       from:07/01/1998 till:01/01/2003 color:guitar
 bar:Gray       from:02/04/2008 till:end        color:guitar
 bar:MPutman    from:12/01/1999 till:01/01/2003 color:percussion
 bar:Green      from:01/01/1999 till:01/01/2003 color:bass
 bar:Green      from:02/04/2008 till:end        color:bass

References[link]

Further reading[link]

• "Living Sacrifice". 7ball (14). September / October 1997. 

External links[link]

• Official website (MySpace)