3.2 Geographic distribution patterns
The taxonomic and phylogenetic similarities of both abundant and rare
taxa exhibited significantly negative relationships with corresponding
geographic distance (all P < 0.05, Fig. 2a and 2b).
However, the slopes of distance-decay of compositional and phylogenetic
similarity were steeper for abundant taxa (Bray-Curtis, 0.0084; βMNTD,
0.0013) than those for rare taxa (Bray-Curtis, 0.0038; βMNTD, 0.0003),
indicating a stronger influence of dispersal limitation for abundant
taxa. Moreover, significantly higher taxonomic and phylogenetic
β-diversity values were found in rare taxa than for the corresponding
abundant taxa (Wilcoxon rank-sum test, P < 0.001, Fig.
2c and 2d). Additionally, significant correlations between community
composition and phylogeny were observed in both the abundant and rare
subcommunities (all P < 0.001, Fig. S3). The
correlation in the rare subcommunity (R2 = 0.829) was
much stronger than that in the abundant subcommunity
(R2 = 0.149).
VPA results revealed that the pure effect of spatial variables was
consistently higher than that of environmental factors for both the
abundant (16.9% versus 3.5%) and rare (7.9% versus 1.5%)
subcommunities (Fig. S4). The pure effect of land use types accounted
for the smallest portions of the variability in both the abundant and
rare subcommunities. However, of all the environmental variables and
land use types examined, forest area by itself explained 7.7% of the
variation in the abundant subcommunity, more than any of the other
individual sediment variables (Table S3).