05 May 2010

Argentine Pirate Ants

Last night Stephen Colbert interviewed a myrmecologist with a new book out.  If you've glanced even casually at previous Zblog entries you've probably noticed the recent development of a borderline unhealthy fascination (obsession?) with ants--so this was right up my alley.  The myrmecologist was Mark Moffett, (whose surname brings back warm memories of living on Moffett Field when I worked for SETI in 2006), and the book he wrote looked amazing, so if you haven't gotten me a birthday present yet...

Moffett announced that California was being invaded by Argentine Ants (Linepithema humile) who are terrific at stowing away on boats.  Colbert took this to indicate that these were "Pirate Ants."  But if my sources are correct (and Johnny Depp is rarely wrong), pirates are rarely stowaways, preferring instead to make their presence felt quite dramatically. These ants are more like armies of conquistadores than simple pirates.  They come, they detect chemical signals, they conquer.

But when these ants get on boats and spread themselves across the globe, the genetic diversity manifested by the original Argentine colonies are not represented and replicated in the New World.  This means that the majority of the Argentine ants who have immigrated across the world are relatively inbred.  Ants use genetically mandated pheromone markers to tell the difference between citizens and foreigners, so when all the ants have similar genetics,  and thus similar pheromone markers, the ants aren't just little family units in little colonies, they form really, really big "super-colonies."

Stretching 560 miles, count-em 560 MILES along the coast of California, the "California Large Colony" (really creative naming, myrmecologists) is one of the three largest known super-colonies in the world. Pirates, shmirates, conquistadores, conquistashmores; it's impossible to find an apt anthropomorphic metaphor for these armies of stowaways whose arrival at each new port typically foreshadows the displacement of most if not all of the ants who lived their natively.

In the past few years, researchers have reported that in fact several Argentine mega-colonies from around the globe belong to a single super-giganto "mega-colony."  All of the ants in these colonies recognize the same pheromonal markers as their intra-continental brethren.  Here's a quote from the article announcing the global mega-colony, published in the journal Insect Sociaux"The enormous extent of this population is paralleled only by human society."  The BBC article reporting on the discovery of the colony chose the following headline: Ant mega-colony takes over world. That's right, the world.  This mega-colony is the largest social structure of its type, and it is continuing to expand, thanks to the lifts we are nice enough to give with our fancy boats.  

 Hey humanity, put that in your pipe and smoke it.  

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