I’m going to expand upon yesterday’s post about invasive animals in Florida. Pythons are indeed large aggressive predators, but it isn’t as though they chose to move to Florida like Aunt Edna when she retired. Enthusiasts brought them from Burma. The pythons escaped or were set free and they found a way to survive.
Florida’s groves of tasty, tasty oranges are hardly natives either. Over long centuries, Spaniards carefully hybridized trees that bore perfect sweet fruit. They then carried saplings across the oceans from the fragrant orchards of Iberia.
We humans are ourselves an invasive tropical species from Africa. As we have explored the world, we have encountered all sorts of useful and interesting plants and animals. Thereafter we took those friends with us. Dogs, ducks, and dairy cows, roses, rye and rice–all of our favorite living things are invaders of a sort. Sometimes we make bad or dubious friends (pythons? really?) but our existence depends on the grains we harvest, the fruit we grow, and the animals we farm. Such is the price of our success. If we all returned to fishing, hunting, and gathering, we could expect to remove three or four zeros from our total population number of six billion.
The story of invasive species however extends far beyond humankind’s symbiotic alliances and restless propensities. A couple of quick examples will clarify this point. Like the pythons, Florida’s native manatees have a great deal of trouble with cold weather. Every winter, many starve to death in the warm outflows from power stations where they shelter (or they freeze outright). They must have expanded their range northwards as the ice ages ended. The armadillos that live on the panhandle are edentates who began trekking out of South America during the Pliocene (3 million years ago) when the Ismuth of Panama formed and rejoined the sundered Americas.
This story goes on and on and gets bigger and bigger: flowering plants showed up from elsewhere, so did mammals and reptiles back in the Paleozoic Era. In fact, if you go back far enough all life-forms are invaders.