Polyploidy commonly occurs in invasive species, and phenotypic plasticity (PP, the ability to alter one's phenotype in different environments) is predicted to be enhanced in polyploids and to contribute to their invasive success. However, empirical support that increased PP is frequent in polyploids and/or confers invasive success is limited. Here, we investigated if polyploids are more pre‐adapted to become invasive than diploids via the scaling of trait values and PP with ploidy level, and if post‐introduction selection has led to a divergence in trait values and PP responses between native‐ and non‐native cytotypes. We grew diploid, tetraploid (from both native North American and non‐native European ranges), and hexaploid
This content will become publicly available on September 1, 2024
Increased genome‐material costs of N and P atoms inherent to organisms with larger genomes have been proposed to limit growth under nutrient scarcities and to 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 trade‐offs is limited.
We grew diploid, autotetraploid, and autohexaploid
Relative to diploids, polyploids invested more N and P into cells, and tetraploids grew more with 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 genome size) 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.
N and P material costs increase with ploidy level, but material‐cost constraints might be lessened by 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 genome‐size)‐specific performances, cytogeographic patterning, and multispecies community structuring.
- Award ID(s):
- 1941309
- NSF-PAR ID:
- 10482677
- Publisher / Repository:
- American Journal of Botany
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 110
- Issue:
- 9
- ISSN:
- 0002-9122
- Subject(s) / Keyword(s):
- ["genome size, material costs, nitrogen, nutrient-use, phosphorus, photosynthesis, polyploidy, transcriptome size"]
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Solidago gigantea in pots outside with low, medium, and high soil nitrogen and phosphorus (NP) amendments, and measured traits related to growth, asexual reproduction, physiology, and insects/pathogen resistance. Overall, we found little evidence to suggest that polyploidy and post‐introduction selection shaped mean trait and PP responses. When we compared diploids to tetraploids (as their introduction into Europe was more likely than hexaploids) we found that tetraploids had greater pathogen resistance, photosynthetic capacities, and water‐use efficiencies and generally performed better under NP enrichments. Furthermore, tetraploids invested more into roots than shoots in low NP and more into shoots than roots in high NP, and this resource strategy is beneficial under variable NP conditions. Lastly, native tetraploids exhibited greater plasticity in biomass accumulation, clonal‐ramet production, and water‐use efficiency. Cumulatively, tetraploidS. gigantea possesses traits that might have predisposed and enabled them to become successful invaders. Our findings highlight that trait expression and invasive species dynamics are nuanced, while also providing insight into the invasion success and cyto‐geographic patterning ofS. gigantea that can be broadly applied to other invasive species with polyploid complexes. -
more » « less
Abstract Aim Polyploids have been theorized to occur more frequently in environments that are subjected to severe conditions or sudden disruptions. Here we test the expectation that polyploid taxa occur more frequently in extreme or disrupted environments than their diploid counterparts, whether due to increased adaptive potential, environmental resilience or cross‐ploidy competition.
Location South America.
Taxon All frog genera in the area with both polyploid and diploid member species (
Ceratophrys, Chiasmocleis, Odontophrynus, Phyllomedusa andPleurodema ).Methods In all, 13,556 occurrence records of 82 frog species were collected from the Global Biodiversity Information Facility. Species distribution models, range overlap estimates, statistical tests and principal component analyses were used to estimate and compare environments between diploid and polyploid species within and across genera using several categorical and quantitative variables taken from multiple publicly available sources.
Results Almost all polyploid occurrences are found within southeastern South America, largely to the exclusion of diploids. Polyploid species occur more closely with intergeneric polyploids than they do with congeneric diploids. Southeastern South America is more temperate, seasonal and less forested when compared to the tropical environments more commonly inhabited by diploids. The habitat ranges of polyploid species are subject to greater temperature fluctuations than diploid species. This region has also experienced major transformations in the modern era, owing to an agriculture boom over the last century. Polyploid occurrences are more likely to be found in areas with greater cropland usage, fertilizer application and pesticide application than diploids.
Main Conclusions Across species, temperature seasonality was the only variable with strong statistical differences between diploids and polyploids. Greater annual fluctuations in temperature may lead to more established polyploid species due to reasons mentioned above; however, extreme temperature differences are also known to contribute to polyploid gamete formation, providing a possible non‐selective explanation. Polyploid occurrences are also more likely to be found in areas of high agricultural impact, providing support for the hypothesis that polyploids are more resilient to environmental disruptions than diploids.
-
Purugganan, Michael (Ed.)Abstract Whole-genome duplication (polyploidization) is among the most dramatic mutational processes in nature, so understanding how natural selection differs in polyploids relative to diploids is an important goal. Population genetics theory predicts that recessive deleterious mutations accumulate faster in allopolyploids than diploids due to the masking effect of redundant gene copies, but this prediction is hitherto unconfirmed. Here, we use the cotton genus (Gossypium), which contains seven allopolyploids derived from a single polyploidization event 1–2 Million years ago, to investigate deleterious mutation accumulation. We use two methods of identifying deleterious mutations at the nucleotide and amino acid level, along with whole-genome resequencing of 43 individuals spanning six allopolyploid species and their two diploid progenitors, to demonstrate that deleterious mutations accumulate faster in allopolyploids than in their diploid progenitors. We find that, unlike what would be expected under models of demographic changes alone, strongly deleterious mutations show the biggest difference between ploidy levels, and this effect diminishes for moderately and mildly deleterious mutations. We further show that the proportion of nonsynonymous mutations that are deleterious differs between the two coresident subgenomes in the allopolyploids, suggesting that homoeologous masking acts unequally between subgenomes. Our results provide a genome-wide perspective on classic notions of the significance of gene duplication that likely are broadly applicable to allopolyploids, with implications for our understanding of the evolutionary fate of deleterious mutations. Finally, we note that some measures of selection (e.g., dN/dS, πN/πS) may be biased when species of different ploidy levels are compared.more » « less
-
more » « less
Premise of the Study Polyploids possess unique attributes that influence their environmental tolerance and geographic distribution. It is often unknown, however, whether cytotypes within mixed‐ploidy populations are also uniquely adapted and differ in their responses to environmental change. Here, we examine whether diploids and hexaploids from a single mixed‐ploidy population of
Solidago altissima differ in plasticity and potential response to natural selection under conditions simulating climate change.Methods Clonal replicates of diploid and hexaploid genotypes were grown in a randomized split‐plot design under two temperature (+1.9°C) and two watering treatments (–13% soil moisture) implemented with open‐top passive chambers placed under rainout shelters. Physiological, phenological, morphological traits, and a fitness correlate, reproductive biomass, were measured and compared among treatments.
Key Results Differences in traits suggest that diploids are currently better adapted to low‐ water availability than hexaploids. Both ploidy levels had adaptive plastic responses to treatments and are predicted to respond to selection, but often for different traits. Water availability generally had a stronger effect than temperature, but for some traits the effect of water depended on temperature.
Conclusions Diploid and hexaploid
S. altissima may maintain fitness in the short term through adaptive plasticity and evolution depending on which traits are important in a warmer, drier environment. Hexaploids may be at a disadvantage compared to diploids because fewer traits were heritable. Our results underscore the importance of studying combinations of climate variables that are predicted to change simultaneously. -
more » « less
ABSTRACT 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 cytotype‐specific 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 lowerE , andA netandE rates decreased as plants aged. Autotetraploids also had larger and fewer stomata, higher biomass and largerA netthan 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 autotetraploidS. gigantea might render them more competitive for resources and niche space than diploids.
