Supplementary Table S1. Environmental, host-related, and arthropod-related variables (or
abbreviations) used in multivariate models.
Supplementary Table S2. The most prevalent phylotypes (present in more than 6% of the
samples) in bacterial communities of ticks (D. variabilis and I. scapularis) and fleas (C.
pseudagyrtes and O. leucopus). Best match: bacterial classification from known sequences that
best matched the sample sequence (highest bit score); P: Prevalence, % infected; I: Intensity,
average relative abundance of each bacterial phylotype in infected arthropods. Asterisks indicate
that the phylotype was unique to one arthropod species. Abbreviations: DV = Dermacentor
variabilis; IS = Ixodes scapularis.
Supplementary Table S3. Results of non-parametric multiple regression of multivariate
bacterial phylotype data on sets of environmental, host-related, and arthropod-related variables.
Sets of variables were inserted to the model using forward procedure (McArdle and Anderson
2001). %Var: percentage of variance in bacterial composition explained by that set of variables
and Cum. %: cumulative percentage of variance explained. Individual variables in each set are
shown in Supplementary Table S1.
Supplementary Fig. S1. Map of the 24 sampling plots (yellow circles at eight sites) across
Indiana.
Supplementary Fig. S2. Relative abundance (percentage of sequences classified into each
genera out of the total sequences) of bacterial genera (Family and Orders are provided where
phylotypes were not classified to lower taxonomic levels; UG = Unclassified Genus) in
Dermacentor variabilis (N = 91), Ixodes scapularis (N = 41), Ctenophthalmus pseudagyrtes (N
= 23), and Orchopeas leucopus (N = 43) based on the 103 most common phylotypes that were
described by 454 sequencing and bioinformatics analyses. The most abundant sequences are
given for each species; “others” indicates all remaining sequences. Taxonomic groups identified
in previous studies of the microbiota of ticks, fleas, or both are indicated by one, two, or three
asterisks, respectively (Andreotti et al 2011, Clay and Fuqua 2011, Jones et al 2008, Jones et al
2010, Martin and Schmidtmann 1998, Moreno et al 2006, Murrell et al 2003, Rudolf et al 2009,
van Overbeek et al 2008, Yuan 2010).
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