scholarly journals Is There More to Within-plant Variation in Seed Size than Developmental Noise?

2021 ◽  
Author(s):  
Christophe Pélabon ◽  
Francesca De Giorgi ◽  
Øystein H. Opedal ◽  
Geir H. Bolstad ◽  
Astrid Raunsgard ◽  
...  
Keyword(s):  
Seed Size ◽  
Size Variation ◽  
Developmental Instability ◽  
Source Population ◽  
Short Term ◽  
Plant Variation ◽  
Environmental Predictability ◽  
Environmental Unpredictability ◽  
The Mean ◽  
Developmental Noise

AbstractWithin-plant variation in seed size may merely reflect developmental instability, or it may be adaptive in facilitating diversifying bet-hedging, that is, production of phenotypically diverse offspring when future environments are unpredictable. To test the latter hypothesis, we analyzed patterns of variation in seed size in 11 populations of the perennial vine Dalechampia scandens grown in a common greenhouse environment. We tested whether population differences in the mean and variation of seed size covaried with environmental predictability at two different timescales. We also tested whether within-plant variation in seed size was correlated with independent measures of floral developmental instability and increased under stressful conditions. Populations differed genetically in the amount of seed-size variation occurring among plants, among infructescences within plants, and among seeds within infructescences. Within-individual variation was not detectably correlated with measures of developmental instability and did not increase under stress, but it increased weakly with short-term environmental unpredictability of precipitation at the source-population site. These results support the hypothesis that greater variation in seed size is adaptive when environmental predictability is low.

The effect of plant density, date of apical bud removal and leaf removal on the growth and yield of single-harvest Brussels sprouts (Brassica oleracea var. gemmifera D.C.): II. Variation in bud size

1974 ◽  
Vol 83 (3) ◽  
pp. 489-496 ◽  
Author(s):  
N. M. Fisher
Keyword(s):  
Standard Deviation ◽  
Plant Density ◽  
Size Fraction ◽  
Size Variation ◽  
Plant Variation ◽  
Brussels Sprouts ◽  
Apical Bud ◽  
Bud Size ◽  
The Mean ◽  
Bud Removal

SummaryA method is suggested for estimating the mean bud size and standard deviation of a sample of sprout buds, separated into size grades by the use of riddles. From the standard deviation a potential size fraction is estimated, being the fraction of the buds occurring in a size grade of 10 mm width if the mean bud size were located at the mid-point of the grade. This estimate of bud size uniformity was independent of date of sampling for a period of at least 4 weeks.The potential size fraction was increased by stopping (apical bud removal) and in some cultivars an optimum stopping date was indicated. Increased plant density also increased the potential size fraction, particularly in unstopped crops. Between-plant variation in bud size was significantly greater for the hybrid Thor than the outpollinating Seven Bills but within-plant variation was the more important component of overall bud size variation and was greatly reduced by stopping and by increased plant density in unstopped crops. Mean bud size at any harvest date was increased by early stopping and lower plant density.It is concluded that the date of stopping should be chosen to minimize bud size variation and the plant density varied to spread maturity.

Spatial variation in seed size and seed set on spikes of some Canadian spring wheat cultivars

1991 ◽  
Vol 71 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Keith G. Briggs
Keyword(s):  
Seed Size ◽  
Seed Mass ◽  
Size Variation ◽  
Triticum Aestivum L ◽  
Quadratic Functions ◽  
Pure Stand ◽  
Wheat Cultivars ◽  
Frequency Distributions ◽  
Significant Variance ◽  
The Mean

The seed size (mass) distribution of grain on individual spikes of four Canadian wheat cultivars (Glenlea, HY320, Pitic 62 and Neepawa, Triticum aestivum L.) was determined on plant samples from two replicates of the 1984 High Yielding Wheat Cooperative trial grown at Ellerslie, Alberta. Specific grain mass was determined for individual floret locations on all spikes of each plant, and sterile floret locations were also determined. For all four cultivars the maximum amount of seed size variation from the samples was attributable to variation at the floret level, accounting for 92% of the seed size variance of Pitic 62, down to 74% for Neepawa. Neepawa differed from the other three cultivars in demonstrating a high (20%) and significant variance in seed size attributable to spikelet position. Pitic 62 was the only cultivar of the four that demonstrated significant variance (12%) due to plant differences within replicates. Consistent with previous literature, approximately 50% of total plant yield was accounted for by the mainstem spike, decreasing to 8 to 15% on the third spike. The mean number of seeds spike−1 on the mainstem was 26.8 (Neepawa), 35.9 (Glenlea), 46.8 (HY320) and 48.6 (Pitic 62), but this number decreased in response to tiller order, as did seed mass and floret fertility. Quadratic functions were calculated fitting seed mass to floret position (1 proximal to 4 distal), and were significant in all cases, with R2 values of 63% for Neepawa, 56% for Glenlea, 82% for Pitic 62 and 89% for HY320. The fitted quadratics suggest an optimization of seed size at floret site 2 for some cultivars, with a rapid decrease in seed size at floret sites 3 and 4, especially for the high-yielding cultivars Glenlea and Pitic 62. Fourth florets of the latter cultivars were shown in frequency distributions to produce seeds smaller than the mean seed size of the Neepawa seed size expected at Florets 1, 2 and 3. Large negative skewnesses for seed size for Glenlea, HY320 and Pitic 62 also underscored the tendency for the high-yielding cultivars to produce relatively large numbers of small seeds. Although determined in only one site-year, these differences in seed size distribution pattern amongst cultivars are of major significance to visual identification systems. Large-seeded, high-yielding wheats in pure stand can be expected to produce a significant number of small-seeded kernels that might be confused by visual inspection with CWRS seed type. Key words: Grain, grading, cultivar registration, seed identification, high-yielding wheats

scholarly journals Coping with environmental uncertainty: dynamic bet hedging as a maternal effect

2009 ◽  
Vol 364 (1520) ◽  
pp. 1087-1096 ◽  
Author(s):  
Angela J Crean ◽  
Dustin J Marshall
Keyword(s):  
Size Variation ◽  
Offspring Size ◽  
Bet Hedging ◽  
Maternal Environment ◽  
Unpredictable Environments ◽  
Theoretical Predictions ◽  
Environmental Unpredictability ◽  
The Mean ◽  
Empirical Tests ◽  
Response To Environmental Change

Mothers in a range of taxa manipulate the phenotype of their offspring in response to environmental change in order to maximize their own fitness. Most studies have focused on changes in the mean phenotype of offspring. Focusing on mean offspring phenotypes is appropriate for species in which mothers are likely to successfully predict the environment their offspring will experience, but what happens when the offspring's environment is unpredictable? Theory suggests that when mothers face uncertainty regarding their offspring's environment, they should increase within-clutch variation in the offspring phenotype (i.e. they should bet hedge). While comparative analyses support the idea that mothers do bet hedge in response to environmental unpredictability, empirical tests are very rare and it remains unclear whether mothers adaptively adjust variance in offspring traits (a phenomenon we call dynamic bet hedging). As a first step towards examining dynamic bet hedging, we reanalysed data from five previously published studies. These studies were across a range of taxa, but all manipulated the maternal environment/phenotype and then examined changes in mean offspring size. We found some support for the theoretical predictions that mothers should increase within-clutch offspring size variation when faced with unpredictable environments. We predict that dynamic bet hedging is more common than previously anticipated and suggest that it has some interesting implications for the studies that focus on shifts in mean offspring traits alone. Hence, future studies should examine maternal effects on both the mean and the variance of offspring traits.

High tolerance of progressive elastic compression in peripheral arterial disease

VASA ◽  
2019 ◽  
Vol 48 (5) ◽  
pp. 413-417 ◽  
Author(s):  
Serge Couzan ◽  
Jean-François Pouget ◽  
Claire Le Hello ◽  
Céline Chapelle ◽  
Silvy Laporte ◽  
...  
Keyword(s):  
Venous Insufficiency ◽  
Ankle Brachial Index ◽  
Arterial Disease ◽  
Return Flow ◽  
High Tolerance ◽  
Compression Stockings ◽  
Short Term ◽  
Poor Tolerance ◽  
The Mean ◽  
Peripheral Arterial

Summary. Background: Theoretically progressive compression stockings, which produce a higher compression at the calf than at the ankle level, improve venous return flow without exacerbating peripheral arterial insufficiency (PAD). We aimed to evaluate the short-term tolerance of elastic progressive compression stockings on peripheral arterial vascularisation in patients with symptomatic PAD and associated mild venous insufficiency. Patients and methods: Monocentric, prospective, open pilot study of 18 patients (acceptability study, 6 x 6 plan) evaluating the short-term tolerance of progressive compression stockings (18 ± 2 mmHg at calf and 8 ± 2 mmHg at ankle level) in patients with PAD (ankle brachial index ABI > 0.60 < 0.75) and chronic venous insufficiency (C1s–C4 stages of the CEAP classification). Day 15 tolerance was evaluated by a composite primary criteria comprising: no decrease > 15 % of ABI on each side, no decrease > 15 % of toe brachial index (TBI) on each side and no decrease > 25 % of the number of active plantar flexions performed while standing. Results: The proportion of men was 77.8 %, mean age was 77.3 ± 7.5 years and no patient were diabetic. At inclusion, the mean low ABI was 0.60 ± 0.04 and the mean high ABI was 0.77 ± 0.18. The mean low TBI was 0.32 ± 0.09 and the mean high TBI 0.46 ± 0.15. The mean number of active standing plantar flexions was 33.0 ± 5.0. The majority of the patients were classified in CEAP C2s and C3 classes (class 2: 16.7 %, class C2s: 27.8 %, class C3: 44.4 %, class C4: 5.6 % and class C4s: 5.6 %). Poor tolerance occurred in no patient. By day 30, no patient had worsening of their arterial and venous symptoms. No adverse events occurred during the study. Conclusions: These results suggest a high tolerance of progressive elastic stockings (18 ± 2 mmHg at calf and 8 ± 2 mmHg at ankle level) in symptomatic PAD.

Evaluation of the Efficacy of ST2 and NT-proBNP in the Diagnosis and Prediction of Short- Term Prognosis in Heart Failure with Reduced Ejection Fraction

2017 ◽  
Vol 9 (04) ◽  
Author(s):  
Shivananda B Nayak ◽  
Dharindra Sawh ◽  
Brandon Scott ◽  
Vestra Sears ◽  
Kareshma Seebalack ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ejection Fraction ◽  
Cardiac Biomarkers ◽  
Double Blind Study ◽  
Short Term ◽  
Double Blind ◽  
Reduced Ejection Fraction ◽  
The Mean ◽  
Design And Methods ◽  
The Relationship

Purpose: i) To determine the relationship between the cardiac biomarkers ST2 and NT-proBNP with ejection fraction (EF) in heart failure (HF) patients. ii) Assess whether a superiority existed between the aforementioned cardiac markers in diagnosing the HF with reduced EF. iii) Determine the efficacy of both biomarkers in predicting a 30-day cardiovascular event and rehospitalization in patients with HF with reduced EF iv) To assess the influence of age, gender, BMI, anaemia and renal failure on the ST2 and NT-proBNP levels. Design and Methods: A prospective double-blind study was conducted to obtain data from a sample of 64 cardiology patients. A blood sample was collected to test for ST2 and NT-proBNP. An echocardiogram (to obtain EF value), electrocardiogram and questionnaire were also obtained. Results: Of the 64 patients enrolled, 59.4% of the population had an EF less than 40%. At the end of the 30- day period, 7 patients were warded, 37 were not warded, one died and 17 were non respondent. Both biomarkers were efficacious at diagnosing HF with a reduced EF. However, neither of them were efficacious in predicting 30-day rehospitalization. The mean NT-proBNP values being: not rehospitalized (2114.7486) and 30 day rehospitalization (1008.42860) and the mean ST2 values being: not rehospitalized (336.1975), and 30-day rehospitalization. (281.9657). Conclusion: Neither ST2 or NT-proBNP was efficacious in predicting the short- term prognosis in HF with reduced EF. Both however were successful at confirming the diagnosis of HF in HF patients with reduced EF.

scholarly journals Nature, Nurture, and Noise: Developmental Instability, Fluctuating Asymmetry, and the Causes of Phenotypic Variation

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1204
Author(s):  
John H. Graham
Keyword(s):  
Fluctuating Asymmetry ◽  
Phenotypic Variation ◽  
Deterministic Chaos ◽  
Monozygotic Twins ◽  
Developmental Instability ◽  
Nonlinear Feedback ◽  
Developmental Variation ◽  
Sewall Wright ◽  
Developmental Noise ◽  
And Behavior

Phenotypic variation arises from genetic and environmental variation, as well as random aspects of development. The genetic (nature) and environmental (nurture) components of this variation have been appreciated since at least 1900. The random developmental component (noise) has taken longer for quantitative geneticists to appreciate. Here, I sketch the historical development of the concepts of random developmental noise and developmental instability, and its quantification via fluctuating asymmetry. The unsung pioneers in this story are Hugo DeVries (fluctuating variation, 1909), C. H. Danforth (random variation between monozygotic twins, 1919), and Sewall Wright (random developmental variation in piebald guinea pigs, 1920). The first pioneering study of fluctuating asymmetry, by Sumner and Huestis in 1921, is seldom mentioned, possibly because it failed to connect the observed random asymmetry with random developmental variation. This early work was then synthesized by Boris Astaurov in 1930 and Wilhelm Ludwig in 1932, and then popularized by Drosophila geneticists beginning with Kenneth Mather in 1953. Population phenogeneticists are still trying to understand the origins and behavior of random developmental variation. Some of the developmental noise represents true stochastic behavior of molecules and cells, while some represents deterministic chaos, nonlinear feedback, and symmetry breaking.

scholarly journals Short term fluctuating temperature alleviates Daphnia stoichiometric constraints

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Esteban Balseiro ◽  
Cecilia Laspoumaderes ◽  
Facundo Smufer ◽  
Laura Wolinski ◽  
Beatriz Modenutti
Keyword(s):  
Nutrient Limitation ◽  
Temperature Fluctuation ◽  
Diel Vertical Migration ◽  
Temperature Treatment ◽  
Short Term ◽  
Fluctuating Temperature ◽  
Rna Content ◽  
Temperature Regimes ◽  
Lake Temperature ◽  
The Mean

AbstractIn this study, we analysed how short term temperature fluctuation interacts with nutrient limitation in the vertical migrating Daphnia commutata. We hypothesize that short term (daily) temperature fluctuation will alleviate nutrient limitation. We carried out experiments analysing growth rates, phosphorus and RNA content of D. commutate grown under four different temperature regimes and two P-limited conditions. Our experiments showed that individuals grown under fluctuating temperature grew more than at the mean temperature. We estimated the expected sizes for the 15 °C treatment based on the Q10 and for the fluctuating temperature treatment. These expected sizes for both treatments resulted well below the observed ones. The P and RNA content of individuals grown at 10 °C were significantly higher than those at 20 °C, and when individuals grown at 10 °C were translocated to 20 °C they exerted an increased growth rate. Our results suggest that, under a regime of diel vertical migration, the temperature alternation would allow migrating organisms to alleviate the effect of severe nutrient limitation maintaining population growth. Under a scenario of global warming, where epilimnetic temperatures will increase, lake temperature will interact with nutrient limitation for consumers, but, organisms may be able to face these changes if they can still regularly move from a cold hypolimnion to a warmer epilimnion.

scholarly journals The Ebb and Flow of Study Abroad: A Comparative Analysis of PRC and International Students in Taiwan

2021 ◽  
Vol 13 (11) ◽  
pp. 5844
Author(s):  
Amy Roberts ◽  
Gregory S. Ching
Keyword(s):  
International Students ◽  
Study Abroad ◽  
Short Term ◽  
Study Abroad Programs ◽  
Term Study ◽  
Republic Of China ◽  
Short Term Study ◽  
The Mean ◽  
Cross Tabulation ◽  
Pacific Community

The dialogue about study abroad is a contemporary trend. Since 2011, enrolments from the People’s Republic of China (PRC) have gradually increased and PRC students have now become one of the largest groups of incoming study abroad participants in Taiwan. In this study, investigators explored the characteristics of PRC students in comparison with other international students studying in Taiwan universities. Data were collected from 1870 study abroad students. Data collected include the various study abroad goals, prior study abroad experiences, the Short-term Study Abroad Situational Change Survey, the revised East Asian Acculturation Measures, the Study Abroad Acculturative Hassles, and their overall study abroad satisfaction. Data analyses included computation of the mean, frequency, cross-tabulation of respondents’ responses for identified questions, and various group comparisons. Implications suggest that the characteristics of PRC students are valuable and potentially transformative markers for sustainable cross-strait ties. Study abroad programs in Taiwan are noted as one piece of the emerging discourse for sustainable co-existence between Taiwan and the PRC. As such, PRC study abroad participants along with faculty and students in Taiwan universities have an opportunity to play a role in reshaping future exchanges as well as transforming themselves into stewards of a trans-Pacific community.

Seasonal Changes in the Water Relations of Eucalyptus behriana F. Muell. And E. microcarpa (Maiden) Maiden in the Field

1984 ◽  
Vol 32 (5) ◽  
pp. 495 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Rainfall Intensity ◽  
Field Measurements ◽  
Canopy Conductance ◽  
Laboratory Studies ◽  
Short Term ◽  
The Mean ◽  
Type Response ◽  
Vapour Pressure Difference

Field observations of some parameters of the water relations of the two eucalypt species E. behriana and E. microcarpa in dry sclerophyll, mallee and woodland vegetation were made at three sites from 1980 to 1983. The mean ( n = 519) water potential measured at dawn (Ψdawn) was -3.07± 0.01 MPa and fluctuated seasonally with rainfall intensity over the range -2.0 ± 0, 1 to -4.4 ± 0.1 MPa ( n = 30). Both species behaved similarly and some osmotic adjustment took place. Mean leaf conductance (gs) varied between 0.151 ± 0.006 and 0.003 ± 0.001 mol m-2 s-1 . Maximum daily values of gs were linearly related to Ψdawn as it fluctuated seasonally. The slope of this linear regression was not significantly different from that relating these values of gs and Ψ, when both were measured concurrently. There were thus no indications of a distinction between the responses of gs to long- and short-term fluctuations of Ψ or of a threshold-type response of gs to Ψ. Field measurements indicated that gs was decreased at high values of vapour pressure difference (Δe). In laboratory studies with seedlings of the two species gs decreased from 0.5 to 0.1 mol m-2 s-I as Δe increased from 0.5 to 3.0 kPa. Leaf and canopy conductance were the predominant plant determinants of transpiration rate (Er) in this type of vegetation which has the capacity to restrict Et via the effect of water potential (Ψ) on gs and also by the response of gs to Δe. Some of the water relations parameters of E. behriana indicated that this species was better able to withstand drought than was E microcarpa.

Elevations in Thyroid-Stimulating Hormone in Normal Subjects after Receiving Short-Term Lithium Carbonate

1988 ◽  
Vol 22 (3) ◽  
pp. 202-204 ◽  
Author(s):  
Merlin V. Nelson ◽  
Vickie Tutag-Lehr ◽  
R. Lee Evans
Keyword(s):  
Lithium Carbonate ◽  
Normal Subjects ◽  
Thyroid Stimulating Hormone ◽  
Short Term ◽  
The Mean ◽  
Early Rise ◽  
State Concentration ◽  
Male Subjects ◽  
Stimulating Hormone

Nine normal, healthy male subjects had significantly elevated thyroid-stimulating hormone (TSH) concentrations while receiving oral lithium carbonate for two weeks. The mean minimum lithium serum concentration was 0.765 mEq/L. The TSH concentrations after 15 days on lithium were significantly correlated to the TSH concentration at baseline. No correlation was found between mean minimum lithium steady-state concentration and TSH concentration after 15 days on lithium. Further research is necessary to determine if a high baseline TSH concentration or an early rise in TSH will predict those patients who will eventually develop hypothyroidism after long-term lithium therapy.

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