Figure Captions
Figure 1. Fine-scale niche differentiation between island foxes and island spotted skunks may influence their host-associated microbiomes. Although they exhibit shared evolutionary history (both mesocarnivore species are within Order Carnivora) and inhabit the same two Channel Islands (SCZ = Santa Cruz Island; SRI = Santa Rosa Island), island foxes and island spotted skunks appear to coexist through niche partitioning. Island foxes tend to be more generalist in their habitat use, diet, and temporal activity, whereas island spotted skunks tend to be more specialist in these areas. Commensal microbial communities may reflect these differences, as depicted in this schematic created with BioRender.com.
Figure 2. Alpha diversity differs by species, but not island.(A) Bacterial species richness (as measured by observed features) and (B) Shannon diversity significantly differed by species, with foxes exhibiting higher diversity than skunks, but not by island. (C) Bacterial evenness differed by neither species nor island.
Figure 3. Beta diversity differs by species, island, and sequencing plate. We observed significant differences between species when comparing (A) bacterial abundance (as measured using Bray-Curtis Dissimilarity) and (B) bacterial presence (as measured using the Jaccard Index). Differences between island populations (SCZ = Santa Cruz Island; SRI = Santa Rosa Island) were greater within island spotted skunks (C,D) compared to island foxes (E,F), with additional clustering evident by sequencing plate. Fox and skunk silhouettes were created with BioRender.com.
Figure 4. Island foxes and island spotted skunks exhibited the core mammalian microbiome, with differences in relative abundance observed between species and island populations. Each bar represents the combined samples collected from each island population studied, where SCZ indicates Santa Cruz Island and SRI indicates Santa Rosa Island. Each color denotes a distinct bacterial class, with all additional classes summed together and termed “Other”. Taxonomic groups annotated with an asterisk significantly differed between groups of interest during differential abundance testing with ANCOM.