3.3 Influence of host plant use and geographic distance in
genetic variation
Analyses of the influence of host plants and geographic distance on
genetic variation in the H. pungens species complex showed that
host plant use was a better predictor of genetic distance than
geographic distance (Table 2). Mantel correlation tests between host
plant use and genetic distance matrices and between geographic and
genetic distance matrices using the nuclear SNPs dataset were
significant (r = 0.5254; p = 0.0017 and r= 0.4;p= 0.0128, respectively). In addition, the partial Mantel test
indicated that the correlation between host plant distance and genetic
distance matrices remained significant when controlling for geographical
distance (r = 0.6133; p = 0.0001). Likewise, the results of
regressing the matrix of genetic distances on both host plant and
geographic distances showed that both factors significantly affected
genetic differentiation among sampling localities for nuclear SNPs (host
plant coefficient= 0.28497, p= 0.0001; geographic coefficient = 0.00709,
p= 0.0001). Host plant and geographic distance together explained 47.6%
of genetic variation. In contrast, correlation and multiple regression
tests based on mtDNA distance matrix on geographic and host plant
distances yielded non-significant results (Table 2).