A long-term natural experiment hints at how species disperse

THAT SPECIES might spread overseas by hitching lifts on floating vegetation is an idea going back to Charles Darwin. It is a plausible thought, but hard to test. A test of sorts has, however, been made possible by the tsunami that struck the Pacific coast of Japan in 2011, in the wake of a submarine earthquake. The incursion and regression of this tsunami dragged with it millions of pieces of debris, many of them buoyant. After a year or so some of the debris started arriving on the coast of Nor...