Evolution of increased vigour associated with allopolyploidization in a newly formed invasive species

Polyploidy (whole genome duplication) is one of the most important processes in plant evolution. Most land plants have an evolutionary history that includes multiple polyploidization events. Allopolyploidy, hybridization coupled with whole genome duplication, is often considered to be the primary source of successful polyploid plant lineages. The prevalence of allopolyploidy has been hypothesized to be due to associated increases in plant vigor, and in turn competitiveness and in some cases invasiveness. However, this hypothesis has not been investigated experimentally. 

In a recent study published in AoBP, Welles and Ellstrand used a common garden approach to compare the fitness of three species of Russian thistle – an allopolyploid neospecies, Salsola ryanii, and its progenitors, S. tragus and S. australis. The results of the two-year study showed support for the hypothesis that success of allopolyploid lineages is linked to increases in plant vigor. Both aboveground plant mass and volume were elevated in S. ryanii compared to its progenitors. As one of the progenitors is a problematic invasive species that forms tumbleweeds, the authors note that S. ryanii also has the potential to be problematic. They conclude by stating that their study begins to fill the gap in understanding of phenotypic evolution during an allopolyploid speciation event. Further common garden experiments with other newly formed allopolyploid species and their progenitors will help to establish whether the results of this study are representive of all allopolyploids.

Researcher highlight

Shana Welles received her PhD in Plant Biology from the University of California, Riverside in 2015. Shana is currently a Grand Challenges Initiative postdoctoral fellow at Chapman University. In this role, Shana conducts research on the evolutionary ecology of invasive plants, teaches classes to first- and second-year science students where they develop critical thinking and problem-solving skills, and mentors undergraduate students in independent research projects. 

Shana’s research is focused on understanding how invasive plants evolve in their invaded range. Her research combines genomics with trait-based approaches to holistically understand how invasive plants evolve.