Data from: Metabolomic profiling reveals shifts in defenses of an invasive plant

<strong>Abstract</strong>. The Shifting Defense Hypothesis predicts that introduced exotic plants evolve increased defenses against generalist herbivores and decreased defenses against specialists that are often absent in the introduced range. This hypothesis has received mixed evidence, and there is limited insight in its chemical basis from targeted analysis. Here, we provide an untargeted metabolomic analysis of native and invasive Purple Loosestrife populations and we experimentally test if admixture between introduced populations provides a basis for rapid defense chemistry evolution. Invasive populations showed improved growth and generalist herbivore resistance, but lower resistance to a specialist weevil. Metabolomic profiling revealed large shifts in chemistry between native and invasive populations, including differences in alkaloids and flavonoids. Experimental admixture increased chemical diversity and plant growth in the native populations, indicating its potential to fuel rapid evolution, but admixture did not affect generalist and specialist herbivory. Our comprehensive untargeted metabolomics results provide strong support for the Shifting Defense Hypothesis. <strong>Data sets description:</strong> Metabolite data: <strong>LCMS_pos.xlsx</strong> and <strong>LCMS_neg.xlsx</strong> Metabolites were extracted from the 3rd to 4th pairs of leaves (from top to bottom) of experimental <em>Lythrum salicaria</em> plants, which originated from three regions in Europe and three regions in North America, and were analyzed by LC-MS. Electrospray ionization was carried in in positive mode (LCMS_pos.xlsx) and in negative mode (LCMS_neg.xlsx). The LC-MS profiles were analyzed by software SIMCA v13.0, and the number of metabolites and their unique compounds were also classified and analyzed. The data sets show retention times and mass-over-charge ratios (in rows) organized by individual plant samples (in columns). Plant samples were analyzed in four batches (two each for positive and negative mode), and are labeled by their population of origin and cross type: IALS: Iowa – Little South Storm Lake IML: Idaho – Middleton NJS1: New Jersey – Site 1 NW: Netherlands – Wageningen PG: Potsdam – Geltow TR: Tübingen – Reusten Intra: sample from intra-population cross Pop: sample from cross between populations from the same region Reg: sample from cross between populations from different regions Herbivory and plant trait data: <strong>Phenotypes.xlsx</strong> The plant height, main stem width, generalist and specialist feeding results of <em>L. salicaria</em> plants used in the experiments. Data are from individual plants, which are characterized by origin (North America or Europe), Region (three regions per origin), Sample site (three sites per region) and cross type (experimental plant derived from either ‘intrapop’ cross (cross within sample site) or ‘interregion’ cross (cross between sample sites from different regions)). Height: plant height in cm Diameter: main stem diameter in mm Specialist: number of holes eaten on the tested leaf Generalist: total leaf surface area consumed by herboivores (cm2)