scholarly journals Evolutionary responses of a dominant plant along a successional gradient in a salt-marsh system

Plant Ecology ◽  
2021 ◽  
Author(s):  
Qingqing Chen
Keyword(s):  
Grazing Intensity ◽  
Clonal Plant ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Plant Populations ◽  
Genetic Changes ◽  
Successional Gradient ◽  
Number Of Leaves ◽  
Successional Stages ◽  
Favorable Conditions

AbstractThe ecological responses of plant populations along a successional gradient have been intensively examined; however, the evolutionary responses received much less attention. Here, I explored genetic changes of key phenotypic traits of a dominant clonal plant (Elytrigia atherica) along a saltmarsh successional gradient by collecting samples along the successional gradient in the high and low marsh and growing them in a common environment (greenhouse). Additionally, to explore whether changes in traits are driven by abiotic (e.g. clay thickness) and biotic (e.g. grazing intensity) variables along the successional gradient, I measured these two variables in the field. I found that clay thickness (a proxy of total nitrogen) increased along the successional gradient both in the high and low marsh; grazing intensity from hares (the most important herbivores) decreased along the successional gradient in the high marsh but did not change in the low marsh. Meanwhile, I found that growth in number of leaves and ramets decreased, while rhizome length increased, along the successional gradient for E. atherica collected from the high marsh. Opposite trends were found for E. atherica collected from the low marsh. Results suggest that, in the high marsh, herbivores may overrule nutrients to drive trait changes. That is, at the early successional stages, E. atherica had higher growth in number of leaves and ramets to compensate for high-intensity grazing. In the low marsh, nutrients may be the dominant driver for trait changes. That is, at the late successional stages, E. atherica had higher growth in number of leaves and ramets but shorter rhizomes to maximize its expansion under the favorable conditions (higher nutrient availability). Results suggest that ecologically important abiotic and biotic variables such as nutrients and herbivores may also have a substantial evolutionary impact on plant populations.

scholarly journals Evolutionary Responses of A Dominant Plant Along a Successional Gradient in A Salt-Marsh System

2021 ◽  
Author(s):  
Qingqing Chen
Keyword(s):  
Salt Marsh ◽  
Wadden Sea ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Plant Populations ◽  
Genetic Changes ◽  
Herbivore Density ◽  
Successional Gradient ◽  
Number Of Leaves ◽  
Successional Stages

Abstract The ecological responses of plant populations along the successional gradient have been intensively examined; however, the evolutionary responses remain to be elucidated. Here, I explored genetic changes of key phenotypic traits of a dominant plant along a successional gradient, and whether these changes were induced by abiotic and biotic variables. I measured key abiotic (e.g. clay thickness) and biotic variables (e.g. herbivore density) along the successional gradient in the high and low marsh in a Wadden Sea saltmarsh. Also, I collected samples of Elytrigia atherica, grew them in the greenhouse, and measured key functional traits. I found that clay thickness (a proxy of total nitrogen) increased along the successional gradient both in the high and low marsh; herbivore density from hares (the most important herbivores) decreased along the successional gradient in the high marsh. Also, I found that growth in number of leaves and ramets decreased, while rhizome length increased, along the successional gradient for E. atherica collected from the high marsh. Opposite trends were found for E. atherica collected from the low marsh. Results suggest that, in the high marsh, herbivores may overrule nutrients to drive trait changes. That is, at early successional stages, E. atherica had higher growth in number of leaves and ramets to compensate for high-density grazing. In the low marsh, nutrients were the dominant driver for trait changes. These results suggest that ecologically important abiotic and biotic variables such as nutrients and herbivores may also have a substantial evolutionary impact on plant populations.

scholarly journals Genotypic richness predicts phenotypic variation in an endangered clonal plant

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1633 ◽  
Author(s):  
Suzanna M. Evans ◽  
Elizabeth A. Sinclair ◽  
Alistair G.B. Poore ◽  
Keryn F. Bain ◽  
Adriana Vergés
Keyword(s):  
Genetic Diversity ◽  
Phenotypic Variation ◽  
Strong Predictor ◽  
Clonal Plant ◽  
Individual Performance ◽  
Tissue Loss ◽  
Phenotypic Traits ◽  
Case Scenario ◽  
Ecological Processes ◽  
Genotypic Richness

Declines in genetic diversity within a species can affect the stability and functioning of populations. The conservation of genetic diversity is thus a priority, especially for threatened or endangered species. The importance of genetic variation, however, is dependent on the degree to which it translates into phenotypic variation for traits that affect individual performance and ecological processes. This is especially important for predominantly clonal species, as no single clone is likely to maximise all aspects of performance. Here we show that intraspecific genotypic diversity as measured using microsatellites is a strong predictor of phenotypic variation in morphological traits and shoot productivity of the threatened, predominantly clonal seagrassPosidonia australis, on the east coast of Australia. Biomass and surface area variation was most strongly predicted by genotypic richness, while variation in leaf chemistry (phenolics and nitrogen) was unrelated to genotypic richness. Genotypic richness did not predict tissue loss to herbivores or epiphyte load, however we did find that increased herbivore damage was positively correlated with allelic richness. Although there was no clear relationship between higher primary productivity and genotypic richness, variation in shoot productivity within a meadow was significantly greater in more genotypically diverse meadows. The proportion of phenotypic variation explained by environmental conditions varied among different genotypes, and there was generally no variation in phenotypic traits among genotypes present in the same meadows. Our results show that genotypic richness as measured through the use of presumably neutral DNA markers does covary with phenotypic variation in functionally relevant traits such as leaf morphology and shoot productivity. The remarkably long lifespan of individualPosidoniaplants suggests that plasticity within genotypes has played an important role in the longevity of the species. However, the strong link between genotypic and phenotypic variation suggests that a range of genotypes is still the best case scenario for adaptation to and recovery from predicted environmental change.

scholarly journals Genetic Divergence among Camu-Camu Plant Populations Based on the Initial Characteristics of the Plants

2016 ◽  
Vol 8 (11) ◽  
pp. 51 ◽  
Author(s):  
Bardales-Lozano Ricardo Manuel ◽  
Edvan Alves Chagas ◽  
Oscar Smiderle ◽  
Abanto-Rodriguez Carlos ◽  
Pollyana Cardoso Chagas ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Divergence ◽  
Indigenous Populations ◽  
Experimental Unit ◽  
Plant Populations ◽  
Mahalanobis Distances ◽  
Canonical Variables ◽  
Measuring Techniques ◽  
Number Of Leaves ◽  
Grouping Method

<p>The objective in the present work was to evaluate the genetic diversity among 15 indigenous populations of camu-camu plants, identifying important characteristics in the evaluation of genetic divergence, based on the initial characteristics of the seedlings. Seeds extracted from fruits deriving from fifteen indigenous populations of camu-camu were collected. The experimental design was entirely random, with fifteen treatments (populations), and fifteen repetitions (each sub-sample), considering 30 seeds per subsample as an experimental unit. At 40 days after sowing the following were evaluated: the percentage of emergence, the index of emergence velocity, the average time of germination, the height of the seedling and the number of leaves. The data obtained was submitted to variance analysis, and the averages were grouped by the Scott and Knott (1974) test. The genetic diversity was studied according to the Tocher grouping method, based on the Mahalanobis distance (D<sup>2</sup><sub>ii</sub>) and canonical variables. The fifteen populations are divergent among themselves and the Rio Branco Estirão do Veado, Rio Branco Onofre and Igarapé Agua Boa populations are indicated to have hybridization with other populations due to the high divergence, as well as the rates of emergence and vigor of the seedlings. The height of the seedlings, percentage and speed of emergence, are those that most indicate genetic divergence. The measuring techniques of genetic divergence, canonical variables Mahalanobis distances are useful and corroborating in the evaluation of genetic divergence of the camu-camu plant.</p>

Conditions de germination et rôle des herbivores dans la dispersion et le recrutement d'une espèce clonale : Juncus gerardi Lois.

2000 ◽  
Vol 78 (11) ◽  
pp. 1430-1439 ◽  
Author(s):  
Bernard Amiaud ◽  
Anne Bonis ◽  
Jan-Bernard Bouzillé
Keyword(s):  
Seedling Survival ◽  
Soil Seed Bank ◽  
Germination Rate ◽  
Rare Event ◽  
Clonal Plant ◽  
Seed Dispersion ◽  
Colonization Success ◽  
Juncus Gerardi ◽  
Favorable Conditions ◽  
Bovine Feces

The finding of new individuals of a clonal plant, Juncus gerardi, raised the question of modalities for the colonization of new sites by this species. Indeed, the existence of seedlings has not been observed in the field, nor reported in the literature for European marshes. Among the parameters limiting recruitment, we examined the soil seed bank, which appeared extremely small. Many seeds could be found in bovine feces but few were found in equine feces. Futhermore, bovines are not only important for seed dispersion, but also for the improvement of the germinative capacities: the seed germination rate of Juncus gerardi was doubled after digestive transit. Germination testing showed that this species is largely tolerant to salinity (from 0 to 26,4 mS·cm-1). The germination rate was maximal with a thermoperiod of 10-20°C but null for a 0-10°C thermoperiod. Germination was improved by immersion and was light dependent. The critical phase for colonization success in new habitats could be primarily seedling survival. Recruitment success in Juncus gerardi seems to be a rare event, requiring the combination of favorable conditions related to climate and gap openings in swards.Key words: germinative capacities, feces, clonal plant, grazers, endozoochory, pastures.

scholarly journals Plant-Mediated Rhizosphere Oxygenation in the Native Invasive Salt Marsh Grass Elymus athericus

2021 ◽  
Vol 12 ◽  
Author(s):  
Ketil Koop-Jakobsen ◽  
Robert J. Meier ◽  
Peter Mueller
Keyword(s):  
Light Exposure ◽  
Root Surface ◽  
Sediment Surface ◽  
Soil Conditions ◽  
Phenotypic Traits ◽  
High Marsh ◽  
Root Zones ◽  
Flooding Frequency ◽  
Elymus Athericus ◽  
Native Invasive

In the last decades, the spread of Elymus athericus has caused significant changes to the plant community composition and ecosystem services of European marshes. The distribution of E. athericus was typically limited by soil conditions characteristic for high marshes, such as low flooding frequency and high soil aeration. However, recently the spread of E. athericus has begun to also include low-marsh environments. A high-marsh ecotype and a low-marsh ecotype of E. athericus have been described, where the latter possess habitat-specific phenotypic traits facilitating a better adaption for inhabiting low-marsh areas. In this study, planar optodes were applied to investigate plant-mediated sediment oxygenation in E. athericus, which is a characteristic trait for marsh plants inhabiting frequently flooded environments. Under waterlogged conditions, oxygen (O2) was translocated from aboveground sources to the roots, where it leaked out into the surrounding sediment generating oxic root zones below the sediment surface. Oxic root zones were clearly visible in the optode images, and no differences were found in the O2-leaking capacity between ecotypes. Concentration profiles measured perpendicular to the roots revealed that the radius of the oxic root zones ranged from 0.5 to 2.6 mm measured from the root surface to the bulk anoxic sediment. The variation of oxic root zones was monitored over three consecutive light–dark cycles (12 h/12 h). The O2 concentration of the oxic root zones was markedly reduced in darkness, yet the sediment still remained oxic in the immediate vicinity of the roots. Increased stomatal conductance improving the access to atmospheric O2 as well as photosynthetic O2 production are likely factors facilitating the improved rhizosphere oxygenation during light exposure of the aboveground biomass. E. athericus’ capacity to oxygenate its rhizosphere is an inheritable trait that may facilitate its spread into low-marsh areas. Furthermore, this trait makes E. athericus a highly competitive species in marshes facing the effects of accelerated sea-level rise, where waterlogged sediment conditions could become increasingly pronounced.

scholarly journals Genet assignment and population structure analysis in a clonal forest-floor herb, Cardamine leucantha, using RAD-seq

AoB Plants ◽  
2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Michiaki Tsujimoto ◽  
Kiwako S Araki ◽  
Mie N Honjo ◽  
Masaki Yasugi ◽  
Atsushi J Nagano ◽  
...  
Keyword(s):  
Natural Population ◽  
Draft Genome ◽  
Clonal Plant ◽  
Genetic Distances ◽  
Plant Populations ◽  
Population Structure Analysis ◽  
Dna Microsatellite ◽  
First Time ◽  
Simple Sequence

Abstract To study the genetic structure of clonal plant populations, genotyping and genet detection using genetic markers are necessary to assign ramets to corresponding genets. Assignment is difficult as it involves setting a robust threshold of genetic distance for genet distinction as neighbouring genets in a plant population are often genetically related. Here, we used restriction site-associated DNA sequencing (RAD-seq) for a rhizomatous clonal herb, Cardamine leucantha [Brassicaceae] to accurately determine genet structure in a natural population. We determined a draft genome sequence of this species for the first time, which resulted in 66 617 scaffolds with N50 = 6086 bp and an estimated genome size of approximately 253 Mbp. Using genetic distances based on the RAD-seq analysis, we successfully distinguished ramets that belonged to distinct genets even from a half-sib family. We applied these methods to 372 samples of C. leucantha collected at 1-m interval grids within a 20 × 20 m plot in a natural population in Hokkaido, Japan. From these samples, we identified 61 genets with high inequality in terms of genet size and patchy distribution. Spatial autocorrelation analyses indicated significant aggregation within 7 and 4 m at ramet and genet levels, respectively. An analysis of parallel DNA microsatellite loci (simple sequence repeats) suggested that RAD-seq can provide data that allows robust genet assignment. It remains unclear whether the large genets identified here became dominant stochastically or deterministically. Precise identification of genets will assist further study and characterization of dominant genets.

scholarly journals An Epidemiological Simulation Model with Three Scales of Spatial Hierarchy

2004 ◽  
Vol 94 (8) ◽  
pp. 883-891 ◽  
Author(s):  
Laetitia Willocquet ◽  
Serge Savary
Keyword(s):  
Leaf Size ◽  
Sensitivity Analyses ◽  
Plant Populations ◽  
Ecological Processes ◽  
Deposition Parameters ◽  
Number Of Leaves ◽  
Spatial Hierarchy ◽  
Disease Epidemics ◽  
Potential Efficiency ◽  
Cultivar Mixture

An epidemiological model integrating three organizational scales of host plant populations (e.g., sites, leaves, and plants) is presented. At the lowest (site) scale, the model simulates the dynamics of vacant, latent, infectious, and removed sites. Three types of vacant sites are distinguished, depending on presence of infections at higher scales (leaf or plant). The rate of infection of each type of vacant site is computed according to ratios of autodeposition, allo-leaf-deposition, and allo-plantdeposition. At the leaf and plant scales, the rate of victimization is a function of the rate of infection of vacant sites. Sensitivity analyses showed that deposition patterns (the relative proportions of auto-, allo-leaf-, and allo-plant-depositions) and host structure (leaf size and number of leaves per plant) affected the speed of epidemics at the different scales. Model outputs conformed with results from other approaches in the case of random distribution of the disease. The model hypotheses concerning infection from autodeposited propagules, and their implications for disease epidemics, are discussed. The model can be used to derive relationships between allo-deposition ratios and disease incidences at the three scales. These relationships become simple when disease intensity is low. These relationships may be useful, e.g., to assess the potential efficiency of cultivar mixture to control epidemics. Integration of different organization scales and allo-deposition parameters enables the model to capture important features of epidemics developing in space without using explicitly spatialized variables. Such an approach could be useful to analyze other ecological processes that involve a variety of scales.

scholarly journals Effects of Grazing Intensity on the Regeneration of Woody Species in an Oak Woodland

2017 ◽  
Vol 45 (2) ◽  
pp. 597-601 ◽  
Author(s):  
Aimilia LEMPESI ◽  
Alexia ELEFTHERIADOU ◽  
Zacharoula DELIVASI ◽  
Aikaterini PSYLLIDOU ◽  
Georgios KORAKIS ◽  
...  
Keyword(s):  
Grazing Intensity ◽  
Woody Species ◽  
Livestock Grazing ◽  
Oak Woodlands ◽  
Quercus Frainetto ◽  
Open Canopy ◽  
Heavy Grazing ◽  
Composition And Structure ◽  
Mediterranean Regions ◽  
Number Of Leaves

In the Mediterranean regions, oak forests are commonly used for livestock grazing. However, it is well documented that livestock grazing is an essential factor that can affect the success of natural regeneration of oak and other woody species of the understorey. Consequently, it influences the composition and structure of oak woodlands. The main objective of the present study was to examine the effects of grazing intensity on characteristics of oak seedlings establishment (density, height, number of leaves) and on the diversity of the woody species seedlings. The research was conducted in open canopy Quercus frainetto woodland, grazed by a herd of 500 goats for eight months per year, located in Evros region, north-eastern Greece. The distance from a goat corral was used to represent relative grazing intensity. In May 2016, vegetation measurements were made along transects placed at 50, 150, 300, 600 and 1200 m from the goat corral, running perpendicular to four replicates. According to the results, increased grazing intensity significantly reduced the density, the plant height and the number of leaves of Quercus frainetto seedlings. Grazing intensity did not affect significantly diversity, evenness and dominance indices for the woody species seedlings. However, heavy grazing reduced species richness and the Chao1 index.

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