Genetic and chemical variation of Tanacetum vulgare in plants of native and invasive origin

High genetic diversity of introduced plant populations may pose a key advantage under changed selection pressures but may also have important implications for biological control of such plants. However, molecular markers employed to measure genetic variation do not necessarily reflect variations in phenotypic traits such as plant chemical composition, which may be similarly important for both the invasion success of a plant and the establishment of biological control agents. The Asteraceae species Tanacetum vulgare is of Eurasian origin, but was introduced to North America, where it became invasive in some areas. This species varies greatly in terpene composition, forming different chemotypes. To assess the genetic diversity of T. vulgare in relation to its chemical diversity, we grew populations originating from different sources of the native and introduced ranges under standardized conditions. Using inter simple sequence repeat markers, we found indications for an increased genetic diversity in plants of the introduced compared to the native range. Analyses of volatile profiles of these individuals indicated similarly high chemical diversities in native and introduced populations. Clustering analyses revealed a considerable amount of unique geno- and chemo-types on both continents. No significant relation between the genetic and chemical data could be detected, demonstrating that the genetic structure of invasive populations does not necessarily offer information on its chemical diversity and vice versa. Knowledge of both the genetic structure and the actual variation in plant chemistry allows biological control research to consider factors potentially interfering with the success of biocontrol agents prior to release.