Figure 1.

Non-metric multidimensional scaling ordination of (a) all 198 arthropods based on Bray–Curtis similarities in abundances of the 103 bacterial phylotypes and (b) a subset of 146 arthropods based on Bray–Curtis similarities in abundances of five bacterial phylotypes belonging to the commonest arthropod-specific genera (Rickettsia 1, Francisella 1, Francisella 2, Bartonella 1 and Bartonella 2; Supplementary Table S2 and Supplementary Figure S2). Closer points represent higher similarity in bacterial community composition than points that are further apart. Each point represents an individual arthropod. The division of arthropod to species (green squares for D. variabilis, black circles for I. scapularis, blue triangles for C. pseudagyrtes, and red X's for O. leucopus) was the best explanatory variable of the bacterial community composition within ticks but not fleas. Oval shapes surround bacterial communities in individual arthropods of the same species or two species that were not distinguished based on their bacterial communities.