Invasions by alien plant species are an important component of human-caused global environmental change, often resulting in significant biodiversity and economic losses in the invaded ecosystems. Whether certain traits of species are generally associated with invasion success and can therefore be used to predict and, ultimately prevent biological invasions, is one of the most challenging questions that we have to answer. Plantago virginica is an annual herb, native to North America that has recently invaded China. It has been known to destroy grassland, reduce crop growth and harbor diseases in the introduced range. The general question we want to address is whether there is genetic and phenotypic differentiation between invasive and native regions and among populations within regions. In present study, multiple common gardens were conducted in both China (Invasive region) and USA(Native region) to examine if there were genetically based differences in a suite of life history, morphological and reproductive traits between populations from both the native and introduced range. Meanwhile, we collected leaf samples from a thousand of individual plants presenting over 20 natural populations in both invasive and native region to estimate the genetic diversity and differentiation based on polymorphism of SSR Loci.
Results/Conclusions
From common garden experiments, there were significant differences in traits among populations within regions and between regions. Seeds collected from invasive populations germinated sooner and showed higher germination rate than those from native populations; the populations from lower latitude showed earlier phenological phase; plants originated from invasive populations grew faster and were bigger than those from native populations. From molecular analyses, we found that the genetic diversity in invasive populations decreased and significantly differentiated from native populations; there might be several introductions from different native populations inferred from STRUCTURE analysis, which explained the main sources of variance of genetic diversity in invasive region; changed ratio of cleistogamous to chasmogamous flowers in different populations induced to plastic mating system, which is thought to be critical for successful establishment during species range extension. In general, the success of introduced species ultimately depends on how well their phenotypes can match the abiotic and biotic challenges in new environments. Adaptive and plastic differentiation between native and invasive regions and among populations within regions occurred and contributed to invasion success of P. virginica.