3.2 Biogeography
The following biogeographical analyses were based on the MOTUs (370) delimited by the sGMYC approach (see discussion below). In our dataset, the number of species per sampling location varied from a single species to over 15 species across the different sampling sites at the studied biogeographical realms. Just a few of all sampled locations (3.8%) had 5 or more species present, while 203 (54.9%) of the 370 species included were only recorded at a single location. Since collecting methods, sampling sites, protocols and reporting varied in our dataset, comparisons of overall biodiversity between locations is challenging. Numbers of Polypedilum species and sampled locations varied between regions (Table 1). Our results indicate that 90.2 % of species were recorded only in a single major biogeographical region, while only 36 species spanned two or more of these regions.
The relative diversity and dominance of Polypedilum species as a proportion of the total number of species per region shows a clear divergence between the geographical regions studied (Figure 5). Insufficiently sampled areas (Afrotropical, Australasian and Panamanian) with low numbers of recorded species present low levels of diversity and are dominated by few species. On the other hand, biogeographical regions exhaustively sampled exhibit high numbers of recorded species with the highest degree of species richness (Nearctic, Palearctic, Oriental and Sino-Japanese). Regarding the Neotropics, the region presented moderate levels of Polypedilum species diversity, particularly when compared to the neighboring Nearctic region (Figure 5); however, it is noteworthy that although only 6.2% of the sampling sites are located in the Neotropical region (mostly in South America), 19.1% of the total number of species occurred in this region. Moreover, based on our results, the Neotropical Polypedilum fauna can be considered endemic, since only one unidentified species was also recorded in the Nearctic region.
None of the species accumulation (rarefaction) curves for the biogeographical realms (Figure 6) exhibit asymptote for any area, although the Nearctic sequences may be approaching one. The Afrotropical, Australasian and Panamanian regions presented the lowest levels of diversity. The highest levels of diversity were seen in the Nearctic, Palearctic and Sino-Japanese regions, with the Neotropical and Oriental regions curves being noticeably lower, with levels of diversity which seems to be comparable. Biogeographical realm patterns across the entire assembly (Figure 7a) showed distinct groupings for Afrotropical and Australasian, while the ANOSIM (see Appendix S1) and nMDS results show some overlap between Nearctic and Palearctic regions. The Neotropical Polypedilum fauna despite the closeness to the Nearctic region presents distinct clustering. The different Neotropical zones compose distinct well supported groups (Figure 7b), with some degree of overlap between Southeastern Amazonia and Boreal Brazilian domination zones. In particular, the Palearctic region appears to display affinities for both the Nearctic and Oriental region (Figure 7b).