Abstract
Among the traits whose relevance for plant invasions has recently been suggested are genome size (the amount of nuclear DNA) and ploidy level. So far, research on the role of genome size in invasiveness has been mostly based on indirect evidence by comparing species with different genome sizes, but how karyological traits influence competition at the intraspecific level remains unknown. We addressed these questions in a common‐garden experiment evaluating the outcome of direct intraspecific competition among 20 populations of Phragmites australis, represented by clones collected in North America and Europe, and differing in their status (native and invasive), genome size (small and large), and ploidy levels (tetraploid, hexaploid, or octoploid). Each clone was planted in competition with one of the others in all possible combinations with three replicates in 45‐L pots. Upon harvest, the identity of 21 shoots sampled per pot was revealed by flow cytometry and DNA analysis. Differences in performance were examined using relative proportions of shoots of each clone, ratios of their aboveground biomass, and relative yield total (RYT). The performance of the clones in competition primarily depended on the clone status (native vs. invasive). Measured in terms of shoot number or aboveground biomass, the strongest signal observed was that North American native clones always lost in competition to the other two groups. In addition, North American native clones were suppressed by European natives to a similar degree as by North American invasives. North American invasive clones had the largest average shoot biomass, but only by a limited, nonsignificant difference due to genome size. There was no effect of ploidy on competition. Since the North American invaders of European origin are able to outcompete the native North American clones, we suggest that their high competitiveness acts as an important driver in the early stages of their invasion.
Highlights
Research in plant invasions has progressed in recent years, with data accumulated in global databases (Dawson et al, 2017; Pyšek et al, 2017; van Kleunen et al, 2015, 2018) allowing improvement of our knowledge about the distribution of naturalized species in world regions, and facilitating deeper insights into the mechanisms and traits associated with successful invasions (e.g., Guo, van Kleunen, et al, 2018; Razanajatovo et al, 2016)
These studies contribute to the existing body of invasion literature focusing on the roles that individual species traits and their interactions have on invasions, acting in concert with other factors (Dawson, Burslem, & Hulme, 2011; Pyšek et al, 2015), and depending on the stage of the invasion process (Divíšek et al, 2018; Moodley, Geerts, Richardson, & Wilson, 2013; Pyšek et al, 2009)
In our previous research (Pyšek et al, 2018), an intercontinental comparison of native and invasive populations of common reed (Phragmites australis), we revealed a distinct relationship between genome size and invasiveness at the intraspecific level, similar to that reported for Phalaris arundinacea (Lavergne et al, 2010, but see Martinez, Baack, Hovick, & Whitney, 2018)
Summary
Research in plant invasions has progressed in recent years, with data accumulated in global databases (Dawson et al, 2017; Pyšek et al, 2017; van Kleunen et al, 2015, 2018) allowing improvement of our knowledge about the distribution of naturalized species in world regions, and facilitating deeper insights into the mechanisms and traits associated with successful invasions (e.g., Guo, van Kleunen, et al, 2018; Razanajatovo et al, 2016). More robust evidence has started to appear in the literature that small genomes promote invasion in plants by interacting with other traits (Meyerson, Cronin, & Pyšek, 2016; Pyšek et al, 2018) and that the role of genome size may differ during different phases of the invasion process, playing the major role in the naturalization stage (Kubešová et al, 2010) The mechanism underlying these analyses is that species with large genomes are less likely to be invasive (Suda et al, 2015). We aimed to reveal whether the effects of genome size and ploidy on competitive hierarchies, if there are any, are direct or mediated via plant traits related to karyological features
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
