FIG. 4.

Weighted UniFrac distance between the bacterial (A) and fungal (B) sequences identified from outside air samples collected in Boulder, CO (the present study, identified by dates in May); New Orleans, LA (Rodríguez-Hernández, unpublished data); and an undisclosed location in the midwestern United States (3). Since very few fungal sequences were identified in the libraries constructed from the New Orleans air, these samples were not included in the fungal UniFrac analyses. For the Boulder sequences, we averaged the calculated distances from the forward and reverse reads from each sample since the two directions yielded very similar results.