Gene flow from transgenic crops allows novel traits to spread to sexually compatible weeds. Traits such as resistance to insects may enhance the fitness of weeds, but few studies have tested for these effects under natural field conditions. We created F2 and F3 crop-weed hybrid lineages of genetically engineered rice (Oryza sativa) using lines with two transgene constructs, cowpea trypsin inhibitor (CpTI) and a Bt transgene linked to CpTI (Bt/CpTI). Experiments conducted in Fuzhou, China,...

Hybridization is hypothesized to promote invasiveness, but empirical tests comparing the performance of hybrid versus parental taxa in novel regions are lacking. We experimentally compared colonization ability of populations of wild radish (Raphanus raphanistrum) versus populations of advanced-generation hybrids between wild and cultivated radish (R. sativus) in a southeast Texas pasture, well beyond the known invasive range of hybrid radish. We also manipulated the strength of interspecific competition to better generalize across variable environments. In...

In the spirit of recent calls for species delimitation studies to become more pluralistic, incorporating multiple sources of evidence, we adopted an integrative, phylogeographic approach to delimiting species and evolutionarily significant units (ESU) in the Corallorhiza striata species complex. This rare, North American, mycoheterotrophic orchid has been a taxonomic challenge with regard to species boundaries, displaying complex patterns of variation and reduced vegetative morphology. We employed plastid DNA, nuclear DNA, and morphometrics, treating the C....