Effects of hybridization on chemical diversity and plant–insect herbivore interactions in Salix alba×fragilis

Abstract

Hybridization can create novel chemical traits and enhance plant adaptability to diverse environments. This study examined the effects of hybridization on chemical diversity and ecological interactions in Salix alba×fragilis hybrids from the Elbe River basin (Czechia). We analysed leaf metabolites of hybrids and their parental species for concentration, richness, and structural α- and β-diversity, linking them to herbivorous insect assemblages and soil conditions. Hybrids exhibited intermediate metabolite concentration and richness but showed higher structural α-diversity and distinct structural β-diversity compared with their parents. Hybrid-specific metabolites were structurally related to parental metabolites, indicating minor structural modifications rather than major changes to metabolic pathways following hybridization. Herbivore assemblages were influenced by metabolite richness or structural α-diversity. However, insect group responses varied, and herbivory damage did not correlate with leaf chemistry or differ between hybrids and parents. Soil nitrogen correlated with metabolite structural β-diversity, with hybrids displaying greater chemical variation along nitrogen gradients. These results highlight that hybridization significantly altered structural metabolite diversity. Yet, the structural changes were relatively minor which, together with group-specific responses of herbivores, could explain their modest effect on herbivory. Instead, they may enable these hybrids to flexibly respond to soil conditions, possibly contributing to their widespread occurrence.