Difference between revisions of "Army ant" - New World Encyclopedia

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[[Image:Safari ants tunnel.jpg|right|thumb|African ''[[Dorylus]]'' raid]]
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The name '''army ant''' (or '''legionary ant''') is applied to over 200 known species, in different lineages, together characterized primarily by their aggressive predatory foraging groups, known as "raids", in which huge numbers of [[ants]] all forage simultaneously over a certain area, attacking prey ''en masse''. They also share the habit of not constructing a permanent nest, unlike most ants, and an army ant colony moves almost incessantly over the time it exists. All species are members of the true ant family [[Formicidae]], but there are several groups that have independently evolved the same basic behavioral and ecological syndrome. This syndrome is often referred to as "legionary behavior", and is an example of [[convergent evolution]].
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==Usage, circumscription==
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Historically, "army ant" referred, in the broad sense, to various members of 5 different ant subfamilies: in two of these cases, the [[Ponerinae]] and [[Myrmicinae]], it is only a few species and genera that exhibit legionary behavior; in the other three lineages, [[Ecitoninae]], [[Dorylinae]], and [[Leptanillinae]], ''all'' of the constituent species are legionary. More recently, ant classifications now recognize an additional New World subfamily, [[Leptanilloidinae]], which also consists of obligate legionary species, and thus is another group now included among the army ants.
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A 2003 study of thirty species (by Sean Brady of [[Cornell University]]) indicates that the ecitonine and doryline army ants together formed a [[monophyletic]] group: all shared identical genetic markers that suggest a common ancestor. Brady concluded that these two groups are therefore a single lineage that evolved in the mid-Cretaceous period in [[Gondwana]]<ref>[http://news.bbc.co.uk/2/hi/science/nature/3014011.stm BBC News, Dr. David Whitehouse, "Ant history revealed"] 10 May 2003.</ref>, and so the two subfamilies are now generally united into a single subfamily [[Ecitoninae]], though this is still not universally recognized (e.g. <ref>Engel, M.S., Grimaldi, D.A. 2005. Primitive new ants in Cretaceous amber from Myanmar, New Jersey, and Canada (Hymenoptera: Formicidae). American Museum Novitates 3485: 1–24.</ref>).
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Accordingly, the army ants as presently recognized consist of the following genera:
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Subfamily Ponerinae:
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*''[[Leptogenys]]'' (some species)
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*''[[Onychomyrmex]]''
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*''[[Simopelta]]''
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Subfamily Myrmicinae:
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*''[[Pheidolegeton]]''
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Subfamily Leptanilloidinae:
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*''[[Asphinctanilloides]]''
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*''[[Leptanilloides]]''
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Subfamily Leptanillinae:
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*''[[Anomalomyrma]]''
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*''[[Leptanilla]]''
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*''[[Phaulomyrma]]''
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*''[[Protanilla]]''
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*''[[Yavnella]]''
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Subfamily Ecitoninae:
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*''[[Aenictus]]''
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*''[[Cheliomyrmex]]''
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*''[[Dorylus]]''
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*''[[Eciton]]''
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*''[[Labidus]]''
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*''[[Neivamyrmex]]''
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*''[[Nomamyrmex]]''
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==Ecitoninae==
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{{main|Ecitoninae}}
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[[Image:Eciton burchelli Illustration.png|right|thumb|A soldier of the New World army ant ''[[Eciton burchelli]]'']]
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* Most [[New World]] army ants belong to the subfamily Ecitoninae, and this is the most commonly-known lineage, therefore bears special mention. This subfamily is further broken into two groups, the tribes [[Cheliomyrmecini]] and [[Ecitonini]]. The former contains only the genus ''[[Cheliomyrmex]]'', and the tribe Ecitonini contains four genera, ''[[Neivamyrmex]]'', ''[[Nomamyrmex]]'', ''[[Labidus]]'', and ''[[Eciton]]'', the genus after which the group is named (Brady, 2003, [http://tolweb.org/tree?group=Ecitoninae Tree of Life]). The genus ''Neivamyrmex'' is the largest of all army ant genera, containing some 120 species, all in the [[United States]]. The most predominant species of ''Eciton'' is ''[[Eciton burchellii]]'', whose common name is "army ant" and which is considered to be the archetypal species.
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* The [[Old World]] army ants are divided between the two tribes [[Aenictini]] and [[Dorylini]].
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** The tribe Aenictini is made up of a single genus, ''[[Aenictus]]'', that contains over 50 species of army ant.
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** The tribe Dorylini contains the aggressive driver ants in the genus ''[[Dorylus]]''. There are some 60 species known.
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Army ant taxonomy remains ever-changing, and genetic analysis will continue to provide more information about the relatedness of the various species.
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==Notes==
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<div class="references-small">
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<references />
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</div>
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==External links==
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*[http://www.antweb.org/ A Comprehensive Ant Website]
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*[http://news.bbc.co.uk/2/hi/science/nature/3014011.stm BBC News, Dr David Whitehouse, "Ant history revealed"]  10 May 2003.
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Personal website on research and computer modeling of army ants (with video and images): <br>
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*[http://www.infiniteworld.org/research/introduction.htm Army ant research page]
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==References and further reading==
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*{{cite book | author = Brady, S. | year = 2003 | title = Evolution of the army ant syndrome: the origin and long-term evolutionary stasis of a complex of behavioral and reproductive adaptations. | id = [[Proceedings of the National Academy of Sciences|PNAS]] 100(11): 6575-6579}}
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*{{cite book | author = Gotwald, W.H., Jr. | year = 1995 | title = Army ants: the biology of social predation | publisher = Cornell University Press | location = Ithaca, New York | id = ISBN 0-8014-9932-1}}
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*{{cite book | author = Rice, Nathan H., and A. M. Hutson | year = 2003 | title = Firefly Encyclopedia of Birds | chapter = Antbirds and Army-Ant Swarms | editor = [[Christopher Perrins]] (Ed.) | pages = 449 | publisher = Firefly Books | id = ISBN 1-55297-777-3}}
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*Wilson, Edward O, and Bert Hölldobler, (1990) ''The Ants'' (Pulitzer Prize),
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[[Category:Life sciences]]
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{{credit|146842727}}

Revision as of 16:01, 20 August 2007

African Dorylus raid

The name army ant (or legionary ant) is applied to over 200 known species, in different lineages, together characterized primarily by their aggressive predatory foraging groups, known as "raids", in which huge numbers of ants all forage simultaneously over a certain area, attacking prey en masse. They also share the habit of not constructing a permanent nest, unlike most ants, and an army ant colony moves almost incessantly over the time it exists. All species are members of the true ant family Formicidae, but there are several groups that have independently evolved the same basic behavioral and ecological syndrome. This syndrome is often referred to as "legionary behavior", and is an example of convergent evolution.

Usage, circumscription

Historically, "army ant" referred, in the broad sense, to various members of 5 different ant subfamilies: in two of these cases, the Ponerinae and Myrmicinae, it is only a few species and genera that exhibit legionary behavior; in the other three lineages, Ecitoninae, Dorylinae, and Leptanillinae, all of the constituent species are legionary. More recently, ant classifications now recognize an additional New World subfamily, Leptanilloidinae, which also consists of obligate legionary species, and thus is another group now included among the army ants.

A 2003 study of thirty species (by Sean Brady of Cornell University) indicates that the ecitonine and doryline army ants together formed a monophyletic group: all shared identical genetic markers that suggest a common ancestor. Brady concluded that these two groups are therefore a single lineage that evolved in the mid-Cretaceous period in Gondwana[1], and so the two subfamilies are now generally united into a single subfamily Ecitoninae, though this is still not universally recognized (e.g. [2]).

Accordingly, the army ants as presently recognized consist of the following genera:

Subfamily Ponerinae:

  • Leptogenys (some species)
  • Onychomyrmex
  • Simopelta

Subfamily Myrmicinae:

  • Pheidolegeton

Subfamily Leptanilloidinae:

  • Asphinctanilloides
  • Leptanilloides

Subfamily Leptanillinae:

  • Anomalomyrma
  • Leptanilla
  • Phaulomyrma
  • Protanilla
  • Yavnella

Subfamily Ecitoninae:

  • Aenictus
  • Cheliomyrmex
  • Dorylus
  • Eciton
  • Labidus
  • Neivamyrmex
  • Nomamyrmex

Ecitoninae

A soldier of the New World army ant Eciton burchelli
  • Most New World army ants belong to the subfamily Ecitoninae, and this is the most commonly-known lineage, therefore bears special mention. This subfamily is further broken into two groups, the tribes Cheliomyrmecini and Ecitonini. The former contains only the genus Cheliomyrmex, and the tribe Ecitonini contains four genera, Neivamyrmex, Nomamyrmex, Labidus, and Eciton, the genus after which the group is named (Brady, 2003, Tree of Life). The genus Neivamyrmex is the largest of all army ant genera, containing some 120 species, all in the United States. The most predominant species of Eciton is Eciton burchellii, whose common name is "army ant" and which is considered to be the archetypal species.
  • The Old World army ants are divided between the two tribes Aenictini and Dorylini.
    • The tribe Aenictini is made up of a single genus, Aenictus, that contains over 50 species of army ant.
    • The tribe Dorylini contains the aggressive driver ants in the genus Dorylus. There are some 60 species known.

Army ant taxonomy remains ever-changing, and genetic analysis will continue to provide more information about the relatedness of the various species.

Notes

  1. ↑ BBC News, Dr. David Whitehouse, "Ant history revealed" 10 May 2003.
  2. ↑ Engel, M.S., Grimaldi, D.A. 2005. Primitive new ants in Cretaceous amber from Myanmar, New Jersey, and Canada (Hymenoptera: Formicidae). American Museum Novitates 3485: 1–24.

External links

Personal website on research and computer modeling of army ants (with video and images):

References and further reading

  • Brady, S. (2003). Evolution of the army ant syndrome: the origin and long-term evolutionary stasis of a complex of behavioral and reproductive adaptations.. PNAS 100(11): 6575-6579. 
  • Gotwald, W.H., Jr. (1995). Army ants: the biology of social predation. Ithaca, New York: Cornell University Press. ISBN 0-8014-9932-1. 
  • Rice, Nathan H., and A. M. Hutson (2003). "Antbirds and Army-Ant Swarms", in Christopher Perrins (Ed.): Firefly Encyclopedia of Birds. Firefly Books, 449. ISBN 1-55297-777-3. 
  • Wilson, Edward O, and Bert Hölldobler, (1990) The Ants (Pulitzer Prize),

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