Neopolyploidy causes increased nutrient requirements and a shift in plant growth strategy in Heuchera cylindrica

Functional traits fall along a continuum from resource conservative to acquisitive and are powerful predictors of the ecological settings necessary for a species to persist and establish. As a consequence, a major problem that functional trait analysis could address is understanding the ecological contexts necessary for the persistence of polyploid plants, because early generation polyploids, or “neopolyploids,” are at a high extinction risk. Because neopolyploidy could increase nutrient limitation, growth strategies should shift to accommodate the increased need for resources, but this prediction is untested. To address this gap, we compared the functional trait responses of diploids, synthetic neotetraploids, and naturally occurring tetraploids of Heuchera cylindrica, an herbaceous perennial plant, to nutrient manipulations in a greenhouse experiment. We found strong support for the hypothesis that neotetraploidy increases nutrient requirements, as evidenced by reduced productivity and increased tissue concentrations of nitrogen and phosphorus in neotetraploids. We also found that the repeated formation of independent origins of neotetraploidy led to differing responses to nutrient supply, but neotetraploidy generally shifted functional traits to be more resource acquisitive and inefficient. Taken together, our results suggest that shifts in functional trait responses may constrain the ability of neopolyploids to establish in nutrient-poor habitats.