No abstract

Premise Although polyploidy commonly occurs in angiosperms, not all polyploidization events lead to successful lineages, and environmental conditions could influence cytotype dynamics and polyploid success. Low soil nitrogen and/or phosphorus concentrations often limit ecosystem primary productivity, and changes in these nutrients might differentially favor some cytotypes over others, thereby influencing polyploid establishment. Methods We grew diploid, established tetraploid, and neotetraploid Chamerion angustifolium (fireweed) in a greenhouse under low and high soil nitrogen and phosphorus conditions and different competition treatments and measured plant performance (height, biomass, flower production, and root bud production) and insect damage responses. By comparing neotetraploids to established tetraploids, we were able to examine traits and responses that might directly arise from polyploidization before they are modified by natural selection and/or genetic drift. Results We found that (1) neopolyploids were the least likely to survive and flower and experienced the most herbivore damage, regardless of nutrient conditions; (2) both neo‐ and established tetraploids had greater biomass and root bud production under nutrient‐enriched conditions, whereas diploid biomass and root bud production was not significantly affected by nutrients; and (3) intra‐cytotype competition more negatively affected diploids and established tetraploids than it did neotetraploids. Conclusions Following polyploidization, biomass and clonal growth might be more immediately affected by environmental nutrient availabilities than plant survival, flowering, and/or responses to herbivory, which could influence competitive dynamics. Specifically, polyploids might have competitive and colonizing advantages over diploids under nutrient‐enriched conditions favoring their establishment, although establishment may also depend upon the density and occurrences of other related cytotypes in a population.

Plants require water and nutrients for survival, although the effects of their availabilities on plant fitness differ amongst species. Genome size variation, within and across species, is suspected to influence plant water and nutrient requirements, but little is known about how variations in these resources concurrently affect plant fitness based on genome size. We examined how genome size variation between autopolyploid cytotypes influences plant morphological and physiological traits, and whether cytotypespecific trait responses differ based on water and/or nutrient availability.• Diploid and autotetraploid Solidago gigantea (Giant Goldenrod) were grown in a greenhouse under four soil water:N+P treatments (L:L, L:H, H:L, H:H), and stomata characteristics (size, density), growth (above-and belowground biomass, R/S), and physiological (A net , E, WUE) responses were measured.• Resource availabilities and cytotype identity influenced some plant responses but their effects were independent of each other. Plants grown in high-water and nutrient treatments were larger, plants grown in low-water or high-nutrient treatments had higher WUE but lower E, and A net and E rates decreased as plants aged. Autotetraploids also had larger and fewer stomata, higher biomass and larger A net than diploids.• Nutrient and water availability could influence intra-and interspecific competitive outcomes. Although S. gigantea cytotypes were not differentially affected by resource treatments, genome size may influence cytogeographic range patterning and population establishment likelihood. For instance, the larger size of autotetraploid S. gigantea might render them more competitive for resources and niche space than diploids.

No abstract

Premise of studyIncreased genomic “material costs” of nitrogen (N) and phosphorus (P) atoms inherent to organisms with larger genome sizes (GS) has been proposed to limit growth under nutrient scarcities and promote growth under nutrient enrichments. Such responsiveness may reflect a nutrient‐dependent diploid versus polyploid advantage that could have vast ecological and evolutionary implications, but direct evidence that material costs increase with ploidy‐level and/or influence cytotype‐dependent growth, metabolic, and/or resource‐use tradeoffs is limited.MethodsWe grew diploid, auto‐tetraploid, and auto‐hexaploid Solidago gigantea plants under one of four ambient and enriched N:P treatments and measured traits related to material costs, primary and secondary metabolism, and resource‐use.Key resultsRelative to diploids, polyploids invested more N and P into cells and tetraploids grew more following N‐enrichments, suggesting that material costs increase with ploidy‐level. Polyploids also generally exhibited strategies that could minimize material‐cost‐constraints over both long (reduced monoploid GS) and short (more extreme transcriptome downsizing, reduced photosynthesis rates and terpene concentrations, enhanced N‐use efficiencies) evolutionary time periods. Furthermore, polyploids had lower transpiration rates but higher water‐use‐efficiencies than diploids, both of which were more pronounced under nutrient‐limiting conditions.ConclusionsCollectively we found that NP material costs increase with ploidy‐level but that material‐cost‐constraints might be lessened by organismal resource allocation/investment mechanisms that can also alter ecological dynamics and selection. Our results enhance mechanistic understanding of how global increases in nutrients might provide a release from material‐cost‐constraints in polyploids that could impact ploidy (or GS)‐specific performances, cytogeographic patterning, and multispecies community structuring.This article is protected by copyright. All rights reserved.

No abstract