10. THE NEW GALÁPAGOS. Our stone weapons and antibiotics are just a few of the tools we've created that have inadvertently helped shape the evolution of the species around us. Simply moving around has caused changes, too, many of which may be innocuous but all of which are unintentional. We have moved cane toads, wild pigs, mice, rats, weeds, sparrows, pavement ants and thousands of other species around the world with us. These species have responded to our tools, but they have also responded to the climate and organisms already present in the places we have introduced them. A recent study in Australia found most of the hundreds of plant species introduced there show some evidence of recent evolution, post-introduction, with many of them apparently having evolved smaller, more drought-tolerant forms (Bushwell et al., 2011). Cane toads introduced to Australia are evolving longer legs that aid in colonizing new habitats (for example, Philips et al., 2007). Where cane toads are present snakes are evolving smaller mouths (those with bigger mouths eat cane toads and, in doing so, die). Vultures introduced to the Canary Islands have evolved larger bodies (Agudo et al., 2010). Elsewhere, house sparrows (Johnston and Selander, 2008), cane toads, houseflies and many other species show evidence of evolving differently in different places. Each new place to which we introduce organisms is a kind of island and the species, new versions of Darwin's Galápagos birds.
Ultimately, whereas evolution can be whimsical (think: vampire bats), its general tendencies are predictable. It revisits its best-worn routes. If we continue to manage the world around us as we have managed it in the past, it's likely we'll continue to favor even more of those species that thrive despite us, species that are resistant to our drugs, pesticides and toxins. Such species might get bigger or more beautiful, but probably not. And, a world filled with small, resistant species is not necessarily what we want. It's time to use our knowledge of evolution and its well-worn paths to cultivate a new garden as we plan our future, one seeded with species that benefit rather than harm us.