Biologist Natacha Bodenhausen and colleagues analyzed the naturally occurring bacterial communities associated with leaves and roots of wild Arabidopsis thaliana, a small flowering plant. The researchers found many of the same bacterial genera in both the plants’ leaves and roots. To explain this, the researchers pointed to the general proximity of A. thaliana leaves to the ground and noted that rain splashing off soil could bring soil-based bacteria into contact with the leaves. Alternatively, the researchers noted that wind, which may be a source of bacteria in the aboveground portion of plants, could also bring bacteria to the soil and roots. Either explanation suggests that ______blank