Increased ploidy of Butomus umbellatus in introduced populations is not associated with higher phenotypic plasticity to N and P

Abstract

Separate introductions or post-introduction evolution may lead to multiple invader genotypes or cytotypes that differ in growth rates, biomass or chemical profile responses (phenotype) to a range of environments. If the invader has high trait plasticity to a range of resource levels, then sediment N or P enrichment may enhance invasiveness. However, the ways in which ploidy, plasticity, and available N or P interact is unknown for most species despite the potential to explain spread and impacts by invaders with multiple introduced lineages. We conducted a common garden experiment with four triploid and six diploid populations of Butomus umbellatus, collected from across its invasive range in the United States. Plants were grown under different N or P nutrient levels (4, 40, 200, 400 mg/L N; 0.4, 4, 40 mg/L P) and we measured reaction norms for biomass, clonal reproduction, and tissue chemistry. Contrary to our expectation, triploid B. umbellatus plants were less plastic to variation in N or P than diploid B. umbellatus in most measured traits. Diploid plants produced 172% more reproductive biomass and 57% more total biomass across levels of N, and 158% more reproductive biomass and 33% more total biomass across P than triploid plants. Triploid plants had lower shoot:root ratios and produced 30% and 150% more root biomass than diploid plants in response to increases in N and P, respectively. Tissue chemistry differed between cytotypes but plasticity was similar; N was 8% higher and C:N ratio was 30% lower in triploid than diploid plants across levels of N and plant parts, and N was 22% higher and C:N ratio 27% lower across levels of P and plant parts. Our results highlight differences in nutrient response between cytotypes of a widespread invader, and we call for additional field studies to better understand the interaction of nutrients and ploidy during invasion.

Investigating the effects of whole genome duplication on phenotypic plasticity: implications for the invasion success of giant goldenrod Solidago gigantea

“…Changes in local abiotic and biotic environments from anthropogenic activities, such as urban and agricultural development, can selectively favor some species and/or populations within a species over others and influence the likelihood of invasive species success (MacDougall et al 2013, González-Moreno et al 2015, Hulme 2017. Polyploidy and high levels of PP have jointly been hypothesized to contribute to invasive successes (Hahn et al 2012, Sánchez Vilas and Pannell 2017, Wei et al 2019, Harms et al 2021), although we generally lack sufficient data for a thorough consensus. Here, we examined whether polyploidy in S. gigantea (in which tetraploid cytotypes are invasive; Schlaepfer et al 2008Schlaepfer et al , 2010 is associated with traits and increased plasticity responses that might have conferred invasive success of tetraploid cytotypes in novel ranges characterized by nutrient enrichments.…”

“…being more (Hahn et al 2012, Rejlová et al 2019) and less plastic (Wei et al 2019, Harms et al 2021.…”

Intraspecific trait plasticity to N and P of the wetland invader, Alternanthera philoxeroides under flooded conditions

“…Increased branching, for example, may lead to increased matting on the water surface and more propagules available for dispersal upon disturbance. This is one of only a few studies to examine intraspecific variation in plant traits of A. philoxeroides in the United States, and joins a growing number of studies in the invasion biology literature that demonstrate (1) intraspecific variation in response to biotic or abiotic environmental variables within an invading species (Harms, Cronin, & Gaskin, 2021 ; Lavergne & Molofsky, 2007 ), and (2) the potential importance of phenotypic plasticity for invader success (Bhattarai et al, 2017 ; Castillo et al, 2014 ; Chevin & Lande, 2011 ; Eller & Brix, 2012 ; Geng et al, 2016 ).…”

“…High nitrogen or phosphorus concentrations were based on standard Hoagland's recipe (200 mg/L N; 40 mg/L P), and low concentrations were 2% (nitrogen) or 1% (phosphorus) of the high concentration. These concentrations were chosen to span those used previously to measure nutrient response of A. philoxeroides (Zhang et al, 2017 ) and other rooted wetland invaders (e.g., Butomus umbellatus; Harms, Cronin, & Gaskin, 2021 ; Manolaki et al, 2020 ). All other macro‐ or micronutrients were consistent between solutions.…”

“…Invader response to fertilization or management may depend on genetic structure of invasions, resulting from sexual recombination or the introduction and establishment of populations from multiple native range source locations (Ward et al, 2008 ). The ways in which genetic variation and eutrophication interact during biological invasions is largely unstudied but has begun to receive interest (Harms, Cronin, & Gaskin, 2021 ; Holdredge et al, 2010 ; Kettenring et al, 2011 ; Liao et al, 2016 ), especially with ever‐increasing nutrient inputs to natural systems (Hale et al, 2015 ). For example, the aquatic invasive plant flowering rush ( Butomus umbellatus L.) has multiple genotypes and at least two cytotypes in the United States (Kliber et al, 2005 ), and previous work demonstrated that diploid and triploid populations differed significantly in their growth, resource allocation, and chemical response to N or P (Harms, Cronin, & Gaskin, 2021 ).…”