Population structure: individual-based clustering and pairwise
differentiation
The DAPC of posterior genotype probabilities assigned to their
respective population provenance revealed high overlap between
populations from different forest patch sizes in the BDFFP landscape in
both species (Figure S5). When the DAPCs was performed assigning
populations to patch size groups (1-, 10, 100-ha, and continuous
forests), we observed that populations of R. flaccida in 1-ha
fragments tend to diverge from the main cluster along Axis 1, which
explained >60% of the genetic variation (Figure 3A). With
the reduced dataset, the population in the 1-ha fragment showed little
overlap with the population clusters of 10-, 100-ha, and continuous
forests. The population of C. surinamensis in the 100-ha fragment
using the complete dataset, genotypes diverged along the Axis 1 from the
clusters with the populations in 1-, 10-ha, and continuous forests.
Between the 1-, 10-ha, and continuous forests clusters, genotypes tend
to diverge along Axis 2 which explained 25.9% of the genetic variation.
When we analyzed the reduced dataset the four clusters that correspond
to different forest patch sizes, diverged along both Axis, with little
overlap (Figure 3B).
Pairwise FST comparison of population andFST comparison of the population over loci are
presented in Tables S7 & S8. Global FST measures
across populations in small and large patches were 0.064 for R.
flaccida and 0.191 for C. surinamensis with the complete
dataset. With the reduced dataset FST measures
were lower: 0.014 for R. flaccida and 0.128 for C.
surinamensis . For populations of R. flaccida , mean pairwise
comparison FST values tend to be higher among
small patches, than between small-large patches and within large patches
(Figure 4). Higher values of FST were also
observed for pairwise comparison among small patches for C.
surinamensis , while between small-large patches and within large
patches tended to be lower (Figure 4).
Using the statistical test of AMOVA we group populations of the two
species by patch size (1-, 10-, 100-ha, and continuous) and by size
class (small and large patches). In both species, the major proportion
of the genetic variation observed was explained by variation within
populations. The geographic location of the populations across the
landscape explained to a minor extent the genetic variation observed
(Table 2). The species R. flaccida FST values
tend to be slightly higher among small patches comparison and between
small-large patches comparison, indicating some degree of
differentiation. However, this genetic difference was not significant
(Table 2). On the contrary, genetic differences between small and large
patches were significant for the species C. surinamensis (Table
2).