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

Abstract

Interactions between invaders and resource availability may explain variation in their success or management efficacy. For widespread invaders, regional variation in plant response to nutrients can reflect phenotypic plasticity of the invader, genetic structure of invading populations, or a combination of the two. The wetland weed Alternanthera philoxeroides (alligatorweed) is established throughout the southeastern United States and California and has high genetic diversity despite primarily spreading clonally. Despite its history in the United States, the role of genetic variation for invasion and management success is only now being uncovered. To better understand how nutrients and genotype may influence A. philoxeroides invasion, we measured the response of plants from 26 A. philoxeroides populations (three cp haplotypes) to combinations of nitrogen (4 or 200 mg/L N) and phosphorus (0.4 or 40 mg/L P). We measured productivity (biomass accumulation and allocation), plant architecture (stem diameter and thickness, branching intensity), and foliar traits (toughness, dry matter content, percent N, and percent P). A short‐term developmental assay was also conducted by feeding a subset of plants from the nutrient experiment to the biological control agent Agasicles hygrophila , to determine whether increased availability of N or P to its host influenced agent performance, as has been previously suggested. Alternanthera philoxeroides haplotype Ap1 was more plastic than other haplotypes in response to nutrient amendments, producing more than double the biomass from low to high N and 50%–68% higher shoot: root ratio than other haplotypes in the high N treatment. Alternanthera philoxeroides haplotypes differed in seven of 10 variables in response to increased N. We found no differences in short‐term A. hygrophila development between haplotypes but mass was 23% greater in high than low N treatments. This study is the first to explore the interplay between nutrient availability, genetic variation, and phenotypic plasticity in invasive characteristics of the global invader, A. philoxeroides .

Population genetic differentiation and phenotypic plasticity of Ambrosiaartemisiifolia under different nitrogen levels

“…In contrast, the results showing a non-significant plasticity in relative biomass allocation to roots and shoots in the five other populations (MZ, ML, HG, CC, and HRB) (Figure 2h) suggests that relative biomass allocation in plants from those populations is genetically fixed. Genetically based intraspecific variation in relative biomass allocation to roots and shoots in response to variation in nutrient availability has been reported for other invasive plant species including Plantago virginica (Luo et al, 2019) and Alternanthera philoxeroides (Harms et al, 2023).…”

Impacts of Soil Properties on Species Diversity and Structure in Alternanthera philoxeroides-Invaded and Native Plant Communities

“…A. philoxeroides was located at the center of the CCA diagram, indicating that this invader has high adaptability to various soil factors, which is not only due to its strong phenotypic plasticity, reproductive ability, and stress resistance [24,38] but also its regulation by the 'soil-plant' feedback effect, which further promotes A. philoxeroides expansion [28,29]. C. rotundus positively correlates with N-NH 4 due to the mycorrhizal fungi in its root systems; these mycorrhizal fungi can increase the absorption of soil N-NH 4 and transfer it to the host plant [73,74].…”

“…A. philoxeroides can reduce soil enzyme activity and disrupt the balance of soil microbial communities through allelopathic effects, thus decreasing the abundance of microorganisms that are beneficial to native plants [27]. The performance of A. philoxeroides is also influenced by soil factors; e.g., soil nitrogen addition can increase the stem length and biomass accumulation of A. philoxeroides, and its invasion trend is positively correlated with nitrogen concentration [28,29]. The most abundant soil nutrients, such as phosphorus and potassium, can promote the secretion of more allelopathic substances in A. philoxeroides roots, causing more intense interspecies competition [27,30].…”