Invasive species

Humans have explored the entire face of the planet, but we haven't done so alone. Animals and plants came along for the ride, some as passengers and other as stowaways. Today, these hitchhikers pose one of the greatest threats to the planet's biodiversity, by ousting and outcompeting local species. Islands are particularly vulnerable to invaders. Cut off from the mainland, island-dwellers often evolve in the absence of predators and competitors, and are prone to developing traits that make them easy pickings for invaders, like docile natures or flightlessness. Two years ago, I wrote about…
Paraguay may be the world's most important country. Never mind that it is economically isolated and geopolitically forgettable. Rather, I measure importance by less trivial metrics, and by that of course I mean ants. Paraguayan ants have changed the world. Many of the world's worst pest species evolved on the broad plains of the Paraná river before hitchhiking with human commerce to points abroad. The infamous fire ants in the southern U.S. originated on the Paraná, as did the Argentine Ants that plague California and Europe, along with a rogue's gallery of other trampy and invasive…