Spatial autocorrelation and migration patterns
Results for the spatial autocorrelation of all population pairs in small
patches (1- and 10-ha), and large patches (100-ha, and continuous
forests), for the complete dataset, are summarized for the two species
(Figure 5; Table S9). When we examine all population pairs, irrespective
of the patch size, pairwise genetic and geographic distances show no
correlation based on the Mantel test for both species (R.
flaccida : R2 = 0.074, p-value = 0.269;C. surinamensis R2 = -0.014,p-value = 0.514). Using the dataset with 20% of missing data,
the same pattern was observed (R. flaccida :R2 = 0.006, p-value = 0.5; C.
surinamensis R2 = 0.175, p-value =
0.079). Correlation within pairs of populations of R. flaccida in
small patches showed a positive slope indicating that populations in
small patches as they are farther distant geographically, are more
genetically dissimilar (Figure S8A). This was more pronounced when we
use the reduced dataset (Figure S8D) with a significant correlation
based on the computed Mantel test (R2 = 0.46,p-value = 0.02). For C. surinamensis , a non-significant
positive slope was observed (R2 = 0.389,p-value = 0.068) within populations in small patches. When
pairwise comparisons were computed for populations within large patches,
the genetic distances were not correlated to geographic distances in
both species (Figure S8B, E, H, K). R. flaccida presents a
slightly positive slope (R. flaccida : R2= 0.186, p-value = 0.341), while populations of C.
surinamensis showed a non-significant negative slope (C.
surinamensis: R2 = -0.11, p-value = 0.65). The
reduced dataset with >75% of missing data supports the
same pattern (R. flaccida : R2 = 0.056,p-value = 0.44; C. surinamensis:R2 = -0.055, p-value = 0.56).
The relative migration levels (Nm ) estimated between populations
based on neutral SNPs using the GST and Nmparameters showed similar patterns (Table S10). The network graph using
the Nm parameters suggests a high migration between R.
flaccida populations irrespective of patch size and isolation (Figure
5C, Table S10). Populations in small patches act as source populations
with high relative migration to other forest fragments and continuous
forests across the landscape. While populations in large patches showed
signs of asymmetrical migration among them, significant symmetrical
migration was observed between the populations in the Florestal
continuous forests and the Dimona 100-ha fragment. The migration network
of the species C. surinamensis was less complex with fewer
patches connected by network vertices, suggesting low or no migration
between populations across the landscape (Figure 5D, Table S10).
Population in small patches showed significant relative migration among
them, at a higher rate than with large forest patches. Populations in
large patches were completely isolated (Dimona 100-ha and Dimona
continuous), where no migration was observed. Significant migration was
observed but at a relatively low rate from the Florestal continuous
forest to the closest Km 41 and Cabo Frio continuous forests.