Discuss the origin and significance of diversity within and between species in a named taxonomic group of your choice(Ants).

Topics: Ant, Ants, Symbiosis Pages: 5 (1882 words) Published: November 24, 2008
IntroductionAnts Formīca are arguably the most successful organisms presently on earth. They evolved from a wasp like common ancestor approximately 150 million years ago(2006 Chuck Lydeard)1. Due to their long ecological dominancy amongst insect and short life span they have undergone a high rate of adaptive radiation. Leading to a reasonably large amount of species and inter- species diversity. There are at least 12000 different species of Formicidae (2008 Edward O. Wilson)2 which have colonised almost every landmass on the planet(Alice S. Jones 2006)3 This unique dominancy and prevalence means that Ants presently account for an incomparable 15 to 20%(2000 Ted R. Schultz)4,3 of the world's terrestrial animal biomass. Formīca exhibit eusociality, they have complex rigid social roles and interactions. They form colonies varying form a few hundred to super colonies with billions of individuals. Ant's prevalence is often over looked due to their size and nature. The time when we most notice their vast numbers is when it starts affecting us; but to put it in perspective there are around 1.7billion ants for every person in Scotland(2006 Edward O. Wilson) 5,6.

History of OriginThe Origin of the Ant stems back even further than we originally thought. A new D.N.A. study which included researchers from Harvard University states that they evolved around 140 to 168 million years ago in the Jurassic or Cretaceous period1. This is significant when we analyze how Ants became so successful and diverse. They evolved from the same common ancestor family as wasps called Vespoidea (1999 Denis J. Brothers)7 the similarity is clear in the family velvet ant (Mutillidae,) [See figure 1] which is actually a wasp but exhibits ant like qualities. They originally evolved in a rain forest type climate living predominantly amongst large herbivores. Indeed this is where we see the greatest number of Formīca and variation in species at present3,4. For a long time Ants were scarce making up only around 1 percent of the insect population(2000 David Grimaldi & and Donat Agosti)8. However around 100 million years ago with the appearance of flowering plants the r-selection species experienced a high rate of evolutionary radiation. As a result of this period of adaptive radiation, ants ecological dominancy increased: 20-40% of insects found in fossil deposits from the middle of the Tertiary period are ants8. Flowering plants were the key to the ants increased population; they created a much wider range of niches and thus reduced competition amongst insects, which lead to an increase in insects that ants could utilise as a food source(2006 Moreau CS.)9 Over time ants exhibited complex symbiotic relationships. I noted a good example of this in the Edinburgh Botanic Gardens(Ħ). The Acacia sphaerocephala [See figure 2] is tree native to Central and South America it exhibits a symbiotic relationship with an ant species Pseudo myrmex sphaerocephala. Its thorns are hollow and perfect for the ants to live in protecting them from predators which could disrupt their colonies if on the ground. In turn this mutualistic relationship benefits the tree as the ants guard it from other leaf eating insects. The eusociality social structure exhibited by Formīca is significant to its success. Instinctive genes inherited from its common ancestor Vespoidea give rise to its social colony structure. This is also still seen in most wasps which evolved from the same ancestral family.

Diversity within Formīca-QueensFormīca display a specific, highly organised, affective social colony structure. Diversity within species of Ant is based on the needs of the colony. The colony is even looked at as an organism in itself (a "Super Organism") for the purpose of some field work. Individuals have specific development pathways which lead to specific roles such as, Soldiers, Workers, Drones, Queens, Foragers and food stores (repletes). The development into these different classes is...

References: http://news.bio-medicine.org/biology-news-3/Ancient-ants-arose-140-168-million-years-ago-7286-1/2 http://www.nytimes.com/2008/07/15/science/15wils.html3 http://ngm.nationalgeographic.com/2007/08/ants/did-you-know-learn4 http://www.pnas.org/content/97/26/140285 http://everything2.com/index.pl?node_id=17930206 http://www.gro-scotland.gov.uk/press/2007-news/scotlands-mid-year-population-estimates.html7 "Phylogeny and evolution of wasps, ants and bees" 233- 249.
8 http://www.pnas.org/content/97/25/136789 http://www.ncbi.nlm.nih.gov/pubmed/1660119010 http://www.antnest.co.uk/cycle.html11 "Caste and ecology in the social insects" 21-22.
12 http://www.sciencemag.org/cgi/content/abstract/231/4743/127813 http://science.discovery.com/tv-schedules/special.html?paid=48.13784.23608.0.014 "The Ants"- award winning15 http://www.sasionline.org/antsfiles/pages/honeyants/honey.html16 http://www.msnbc.msn.com/id/14456898/17 http://www.abc.net.au/news/newsitems/200603/s1589516.htm18 http://www.abc.net.au/news/newsitems/200603/s1589516.htmCover page http://upload.wikimedia.org/wikipedia/commons/0/01/Leafcutter_ants_transporting_leaves.jpgFigure 1 http://www.ces.ncsu.edu/chatham/ag/SustAg/velvetant.htmlFigure 2 http://www.infiniteworld.org/sirena/images/sirena_1.htmFigure 3 http://www.sphoto.com/photo.php?photo=875&exhibition=15&pass=public&size=default⟨=engFigure 4 http://www.pbase.com/crocodile/image/32362188Figure 5 http://www.dkimages.com/discover/DKIMAGES/Discover/Home/Animals/Invertebrates/Arthropods/Insects/Bees-Wasps-Ants-and-Sawflies/Ants/Species/African-Driver-Ant/Male/Male-1.htmlFigure 6 http://www.antfarmz.net/html/jack_jumper_ants.htmlFigure 7 http://commons.wikimedia.org/wiki/User:Mehmet_KaratayFigure 8 http://weirdfoods.blogspot.com/2008/04/honeypot-ants.htmlFigure 9 http://www.abc.net.au/reslib/200603/r75784_214295.jpg
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