3.5.2 Genetic diversity and Hardy Weinberg equilibrium
Hybridization and introgression resulted in an increase of genetic
diversity (π, A, Ar, Ho and HE) in the hybrid regions,
which was estimated with the whole set of 5,702 SNPs (Figure 4 and
Supplementary Tables S7- S9). When the genetic diversity parameters were
compared between I. elegans from allopatry and I. elegansfrom sympatry in each of the hybrid regions excluding F1and F2 hybrid individuals, significant differences in
all five estimates (π, Na, Ar, Ho and HE) were detected
for the north-west hybrid region (all estimates were higher in the
north-west hybrid region; Figure 4 and Supplementary Tables S7- S9). We
also found significantly higher Ar, Ho and HE in the
north-west hybrid region compared to the north-central hybrid region
(Figure 4 and Supplementary Tables S7-S9). Similarly, when comparingI. elegans from allopatry and I. elegans from sympatry in
each of the hybrid regions not excluding F1 and
F2 hybrids, all estimates of genetic diversity (π, A,
Ar, Ho and HE) were significantly higher for the
north-west hybrid region than for I. elegans from sympatry and
than for I. elegans from the north-central hybrid region (Figure
4 and Supplementary Tables S7- S9). No significant differences between
regions were detected in the ratio of SNPs at HW disequilibrium per
population (p<0.05; see Supplementary Tables S8-S9).
3.5.3 Genetic differentiation between and within species in
allopatry and sympatry
Consistent with the finding that hybridization, admixture and
introgression results in reduced interspecific differentiation in
sympatry, we found that the overall genetic differentiation betweenI. elegans and I. graellsii was lower in the sympatric
(excluding F1 and F2 hybrids)
(FST=0.691) than in the allopatric distribution
(FST=0.725).
Pairwise
intraspecific population differentiation in I. elegans from
allopatry ranged from FST=0.002-0.245 (8 out of the 10
pairwise FST values were significant at thep <0.05/10), from the north-west hybrid region
(excluding F1 and F2 hybrids) ranged
from FST=0.012-0.100 (3 out of the 3 pairwise
FST values were significant at thep <0.05/3), from the north-central hybrid region
(excluding F1 and F2 hybrids) ranged
from FST=0.004-0.013 (1 out of the 10 pairwise
FST values was significant at thep <0.05/10) (Supplementary Table S10). Pairwise
intraspecific population differentiation in I. graellsii from
allopatry ranged from FST=0.008-0.068 (2 out of the 3
pairwise FST values were significant at thep <0.05/3), from the north-west hybrid region
FST=0.042 (1 out of the 1 pairwise FSTvalues was significant at the p <0.05), and from the
north-central hybrid region ranged from FST=0-0.014 (0
out of the 15 pairwise FST values was significant at thep <0.05/15) (Supplementary Table S11).
Some populations were highly genetically distinct from many populations.
Specifically, the I. elegans Doniños population from the
north-west hybrid region showed comparatively large and statistically
significant genetic differences with several other populations
(Supplementary Tables S10-S11). Similarly, the I. elegans Leuven
population and the I. graellsii Seyhouse population from the
allopatric distributions showed comparatively large and statistically
significant genetic differences with several other populations
(Supplementary Tables S10-S11).