In habitat patch networks reconstructed for the three REGUA sites and large patches, low-abundance bacteria had higher betweenness centrality than other bacteria in these networks, acting to connect graph neighborhoods (Figure 4). As habitat patch networks became less modular with decreasing habitat patch area, nodes with high betweenness centrality were typically low-abundance bacteria and bacteria in the genera Arsenophonus (including Candidatus Phlomobacter), Wolbachia, and Bartonella.
While there was no impact of sample size (i.e., number of parasite individuals) on ASV richness in each network, a greater number of samples may allow detection of more edges between nodes and change the size of a network. Sample size was lowest in small fragments and highest in large fragments, with the exception of F4 which has intermediate area, isolation, and distance to source measurements, but supports a high diversity of parasites. We did not detect a significant correlation between sample size and network modularity (Spearman rho=0.3945, p-value=0.229). Using the subsampling scheme within SpiecEasi, we did not detect a correlation of sample size and proportion of high-confidence network edges (Spearman rho=0.0275, p-value=0.936).
Using ordinations of graphlet orbits as a size-independent comparison of networks [84, 88, 89], habitat patch networks vary with habitat area (Figure 5D) and species-specific networks are distinct within and outside of REGUA (Figure S8). Principal coordinate axis 2 corresponded well to decreasing habitat area, with large fragments positioned higher on the access and gradually decreasing in patch area lower on the axis. Principal coordinate axis 1 primarily illustrated variation in networks from patches F8 and F5. This variation does not correspond with environment, parasite, or bat variables. K-means clustering with 3 groups separated large habitat patch networks (REGUA networks, F10, F9, F7) from small patch networks (F4, F2, F1), and F8 and F5 formed a unique cluster. Species-specific networks also indicated distinctions between within-REGUA and outside-REGUA networks. All within-REGUA networks occupied unique ordination space from outside-REGUA networks within species.