ARMY ANTS

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					 The name army ant (or legionary ant or "Marabunta") is applied to over 200 ant species,
in different lineages, due to 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.
      Another shared feature is that unlike most ant species, army ants do not construct
 permanent nests, and an army ant colony moves almost incessantly over the time it exists.
 All species are members of the true ant family Formicate, but there are several groups that
  have independently evolved the same basic behavioural and ecological syndrome. This
  syndrome is often referred to as "legionary behaviour", and is an example of convergent
                                           evolution.
  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

				
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posted:11/3/2012
language:English
pages:2