Data from: Effects of admixture in native and invasive populations of Lythrum salicaria

Intraspecific hybridization between diverged populations can enhance fitness via various genetic mechanisms. The benefits of such admixture have been proposed to be particularly relevant in biological invasions, when invasive populations originating from different source populations are found sympatrically. However, it remains poorly understood if admixture is an important contributor to plant invasive success and how admixture effects compare between invasive and native ranges. Here, we used experimental crosses in Lythrum salicaria, a species with well-established history of multiple introductions to Eastern North America, to quantify and compare admixture effects in native European and invasive North American populations. We observed heterosis in between-population crosses both in native and invasive ranges. However, invasive-range heterosis was restricted to crosses between two different Eastern and Western invasion fronts, whereas heterosis was absent in geographically distant crosses within a single large invasion front. Our results suggest that multiple introductions have led to already-admixed invasion fronts, such that experimental crosses do not further increase performance, but that contact between different invasion fronts further enhances fitness after admixture. Thus, intra-continental movement of invasive plants in their introduced range has the potential to boost invasiveness even in well-established and successfully spreading invasive species.Phenotypic dataData from offspring of within-population, between-population and between-region crosses of Lythrum salicaria plants originating from North America or Western Europe, grown under 'dry' and 'wet' experimental greenhouse conditions. Data are from individual plants. Information is included on cross type (including parental plant identity) and experimental design (realblock refers to spatial greenhouse blocking and timeblock refers to time-separated replications).primary_data.txtSAS_analysis_scriptStatistical analysis script used for the statistical analyses presented in the manuscript. The script takes the phenotypic data file as input and was written in SAS version 9.4 for Windows