Dry weight and resource allocation patterns among individuals in populations of Plantago major and P. rugelii

1982 ◽  
Vol 60 (11) ◽  
pp. 2424-2439 ◽  
Author(s):  
W. R. Hawthorn ◽  
P. B. Cavers
Keyword(s):  
Frequency Distribution ◽  
Reproductive Effort ◽  
Natural Populations ◽  
Dry Weight ◽  
Life History Trait ◽  
Plantago Major ◽  
Allocation Pattern ◽  
Plant Weight ◽  
Frequency Distributions ◽  
Allocation Patterns

The frequency distributions of log plant weight in 1st-year plants of Plantago major L. and P. rugelii Decne. were studied in greenhouse experiments, including an investigation of associated differences in allocation patterns to plant parts between individuals in various weight classes. The frequency distributions of log plant weight of both plantains were strongly negatively skewed (many large plants and few small ones) at the lowest sowing density, where little or no mortality occurred during the course of the study. At two higher sowing densities significant mortality was noted and the frequency distributions tended to "log normality" or to a significant platykurtosis. The presence of bromegrass (Bromus inermis Leyss.) reduced the weight of individual plantains and resulted in frequency distributions that were essentially "log normal." Growing the two plantains together did not alter the shapes of the frequency distributions achieved in monocultures with and without grass. A possible pattern of changes in the frequency distribution of log plant weight with the passage of time is briefly discussed. Significant differences were observed in the allocation patterns of individuals of P. major within a population to roots, caudices, leaves, supporting reproductive structures, and seeds. The allocation patterns were not normally distributed according to plant weight; thus the use of average values of allocation pattern for the population as a whole should be viewed with caution. The proportional allocation to seeds (reproductive effort) by individuals of P. major from increasingly larger weight classes generally increased at an exponential rate, and more rapidly than simultaneous decreases in root and caudex allocation. The greatest reproductive effort and the greatest number of seeds per plant of P. major were associated with the strongest negative skewness of frequency distribution of log plant weight. First-year plants of P. rugelii exhibited a different response. Very few flowered during the study. However, in a variety of treatments the allocation to root and caudex by individuals which differed in biomass by as much as two orders of magnitude was remarkably constant at about 23%. In contrast, the allocation to belowground structures was much more variable among individuals of P. major, ranging from 50% or more by the smallest individuals to less than 5% by the largest plants. This life-history trait could partly account for the greater survival over winter and longevity observed in natural populations of P. rugelii compared with those of P. major.

Évolution du rapport des sexes de populations de Rumex acetosella le long d'une succession postculturale

1987 ◽  
Vol 65 (12) ◽  
pp. 2668-2675 ◽  
Author(s):  
Josep Escarré ◽  
Claudie Houssard ◽  
Jean Paul Briane
Keyword(s):  
Aboveground Biomass ◽  
Reproductive Effort ◽  
Vegetative Reproduction ◽  
Natural Populations ◽  
Energetic Cost ◽  
Allocation Pattern ◽  
Growing Seasons ◽  
Rumex Acetosella ◽  
High Reproductive Effort ◽  
Successional Stages

The sex ratios of natural populations of Rumex acetosella L. have been recorded during two growing seasons, along a successional gradient of abandoned agricultural fields of various ages (from 6 months to 15 years old), south of Paris. At the same time, male and female ramets have been collected to determine the resource allocation pattern of the different organs. We have observed that females of Rumex acetosella L. were more frequent than males at the younger stages, and that males predominated at the older ones. Concomitantly, there was a decrease in aboveground biomass and in the reproductive effort of the two sexes in the field, with increasing community maturity. The decrease in reproductive effort was confirmed, in controlled conditions, in the female genets only. Females always produced a higher reproductive effort and a higher aboveground biomass than males, which may explain why they were more abundant in the younger successional stages. Otherwise, our results show that sexual reproduction represented a high energetic cost which tended to consume root resources. Females, and mainly those of the younger stages which presented a high reproductive effort, may suffer more than males. The latter, which were more vigorous in vegetative reproduction and less affected by flower production than females, prevailed at older stages.

Structural changes in a Hieracium floribundum (Compositae) population associated with the process of patch formation

1978 ◽  
Vol 56 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Standing Crop ◽  
Structural Changes ◽  
Vegetative Reproduction ◽  
Light Availability ◽  
Dry Weight ◽  
Genetic Change ◽  
Allocation Pattern ◽  
Southern Ontario ◽  
Reproductive Structures ◽  
Allocation Patterns

The contribution of yellow devil hawkweed (H. floribundum) to the total standing crop of an abandoned pasture in southern Ontario increased from approximately 8% to 70% as H. floribundum colonized the pasture by forming patches containing as many as 3400 rosettes/m2. Within the hawkweed population, there was a significant (P < 0.05) shift in the distribution of standing crop from reproductive to vegetative structures and within the vegetative structures from leaves to roots and rhizome during the process of patch formation. These shifts presumably occurred in response to changing environmental conditions (i.e., increasing light availability, reduced soil moisture levels, greater intraspecific competition). The mechanism by which the allocation pattern changed was more likely phenotypic plasticity than genetic change since H. floribundum is an apomict and vegetative reproduction accounted for most recruitment into the population.The frequency distribution of population members in dry weight classes became more negatively skewed during the process of patch formation, but the distribution did not approach log-normality as predicted in some studies. Significant (P < 0.05) differences were observed in the allocation patterns of individuals belonging to different weight classes in the population. Only the largest plants in the population allocated dry weight to reproductive structures.

The effects of shade on growth, development, and resource allocation patterns of three species of foxtail (Setaria)

1981 ◽  
Vol 59 (9) ◽  
pp. 1776-1786 ◽  
Author(s):  
Susanna M. Lee ◽  
Paul B. Cavers
Keyword(s):  
Reproductive Effort ◽  
Dry Weight ◽  
Relative Increase ◽  
Tiller Number ◽  
Setaria Viridis ◽  
Setaria Glauca ◽  
Allocation Patterns ◽  
Growth Development ◽  
Total Dry Weight ◽  
Lower Tolerance

Three weedy foxtail species, Setaria glauca (L.) Beauv., S. verticillata (L.) Beauv., and S. viridis (L.) Beauv. occur in southwestern Ontario. Plants of the three species were grown in pure stands in the open and under one, two, or three layers of cheesecloth which transmitted 71, 40, and 19% of incident insolation, respectively. Six harvests were taken between July and September in which height, tiller number, dry weight of component parts, and leaf area were determined for randomly selected plants of each species. In unshaded conditions, S. verticillata was the tallest species and had the greatest total dry weight per plant. However, this species was the most adversely affected by shade, with significant reductions in tiller number, biomass production, and reproductive effort with increasing shade. Setaria viridis and S. verticillata exhibited a relative increase in allocation to leaves with increasing shade while S. glauca had a relative increase to stems, indicating different strategies in response to shade. The apparent lower tolerance of shade in S. verticillata may help to explain the comparative rarity of this species in southwestern Ontario.

The effects of density, cutting height and white clover (Trifolium repens L.) on the structure of a ryegrass (Lolium spp.) population

1971 ◽  
Vol 77 (3) ◽  
pp. 385-395 ◽  
Author(s):  
W. Harris
Keyword(s):  
Frequency Distribution ◽  
White Clover ◽  
Plant Size ◽  
Plant Weight ◽  
Main Determinant ◽  
Frequency Distributions ◽  
Population Means ◽  
Density Distributions ◽  
Trifolium Repens L ◽  
Cutting Height

SUMMARYA population of 12 ryegrass genotypes was grown at densities of 0·25, 16 and 8 ryegrass + 8 white clover plants per sq ft and was periodically cut to stubble heights of O5 in. or 3 in. For individual plants, yields, tiller numbers, tiller lengths and emerged inflorescence numbers were recorded. Density was the main determinant of plant size, but cutting-height effects were shown, most markedly for the number of inflorescences.Initially the frequency distribution of plant weight was positively skewed under all treatments, but became less skewed for the population at 0–25 plants per sq ft and more skewed for the population at higher densities. Development of the skew was delayed where white clover was grown. Generally, increasing skew was associated with increasing positive kurtosis.Frequency distributions of tiller numbers were less skewed than those of yields. Frequency distributions of tiller length were less skewed than the corresponding higher density distributions of yield and tiller number.Treatment effects on population means demonstrate the different responses which may be obtained with widely spaced plants or those grown in swards. Changes of the frequency distribution of the population are interpreted using the model of Koyama & Kira (1956) and are related to procedures assessing the performance of plants under selection for growth in swards.

Resource allocation in young plants of two perennial species of Plantago

1978 ◽  
Vol 56 (20) ◽  
pp. 2533-2537 ◽  
Author(s):  
W. R. Hawthorn ◽  
P. B. Cavers
Keyword(s):  
Resource Allocation ◽  
Seed Production ◽  
Dry Weight ◽  
Growth Patterns ◽  
Plantago Major ◽  
Perennial Species ◽  
Plant Parts ◽  
Allocation Patterns ◽  
Number Of Leaves ◽  
Perennial Herbs

Growth patterns and biomass allocation to component plant parts in Plantago major and P. rugelii were compared under greenhouse conditions. Within 3 months of germination individuals of P. major were larger and had devoted more dry weight to seed and production of ramets than those of P. rugelii regardless of the number and kind of neighbours. No significant differences in percent resource allocation to roots, caudex, leaves, and spikes were observed between plants of P. major subjected to increased interference, although the actual biomass and number of leaves and spikes were reduced. Mean reproductive (spike) allocation in P. major was about 21%. Although the root biomass within a treatment was similar for the two species, the percent allocation to roots in P. rugelii was two and one-half times greater. Growth of P. major was depressed more by intraspecific neighbours and of P. rugelii by interspecific neighbours. These perennial herbs exhibit disparate allocation patterns as young plants that suggest adaptations to different temporary environments. Plantago major, with its early and sustained diversion of biomass to seed production, is distinctly adapted to exploitation of frequently disturbed sites, while P. rugelii, because of its more extensive root allocation and delayed seed production, seems better adapted to less frequent disturbance.

Using Tolerance-Maps to Generate Frequency Distributions of Clearance and Allocate Tolerances for Pin-Hole Assemblies

2007 ◽  
Vol 7 (4) ◽  
pp. 347-359 ◽  
Author(s):  
Gaurav Ameta ◽  
Joseph K. Davidson ◽  
Jami J. Shah
Keyword(s):  
Mathematical Model ◽  
Statistical Method ◽  
Frequency Distribution ◽  
Probabilistic Representation ◽  
Worst Case ◽  
Frequency Distributions ◽  
One Dimensional ◽  
Material Condition ◽  
Geometric Tolerances ◽  
Case Basis

A new mathematical model for representing the geometric variations of lines is extended to include probabilistic representations of one-dimensional (1D) clearance, which arise from positional variations of the axis of a hole, the size of the hole, and a pin-hole assembly. The model is compatible with the ASME/ ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map (T-Map) (Patent No. 69638242), a hypothetical volume of points that models the 3D variations in location and orientation for a segment of a line (the axis), which can arise from tolerances on size, position, orientation, and form. Here, it is extended to model the increases in yield that occur when maximum material condition (MMC) is specified and when tolerances are assigned statistically rather than on a worst-case basis; the statistical method includes the specification of both size and position tolerances on a feature. The frequency distribution of 1D clearance is decomposed into manufacturing bias, i.e., toward certain regions of a Tolerance-Map, and into a geometric bias that can be computed from the geometry of multidimensional T-Maps. Although the probabilistic representation in this paper is built from geometric bias, and it is presumed that manufacturing bias is uniform, the method is robust enough to include manufacturing bias in the future. Geometric bias alone shows a greater likelihood of small clearances than large clearances between an assembled pin and hole. A comparison is made between the effects of choosing the optional material condition MMC and not choosing it with the tolerances that determine the allowable variations in position.

Bias in Using an Age–Length Key to Estimate Age-Frequency Distributions

1978 ◽  
Vol 35 (2) ◽  
pp. 184-189 ◽  
Author(s):  
S. J. Westrheim ◽  
W. E. Ricker
Keyword(s):  
Frequency Distribution ◽  
Age Distribution ◽  
Length Distribution ◽  
Fish Population ◽  
Systematic Bias ◽  
Parental Age ◽  
Frequency Distributions ◽  
Class Strength ◽  
Key Words Age ◽  
Age Frequency Distribution

Consider two representative samples of fish taken in different years from the same fish population, this being a population in which year-class strength varies. For the "parental" sample the length and age of the fish are determined and are used to construct an "age–length key," the fractions of the fish in each (short) length interval that are of each age. For the "filial" sample only the length is measured, and the parental age–length key is used to compute the corresponding age distribution. Trials show that the age–length key will reproduce the age-frequency distribution of the filial sample without systematic bias only if there is no overlap in length between successive ages. Where there is much overlap, the age–length key will compute from the filial length-frequency distribution approximately the parental age distribution. Additional bias arises if the rate of growth if a year-class is affected by its abundance, or if the survival rate in the population changes. The length of the fish present in any given part of a population's range can vary with environmental factors such as depth of the water; nevertheless, a sample taken in any part of that range can be used to compute age from the length distribution of a sample taken at the same time in any other part of the range, without systematic bias. But this of course is not likely to be true of samples taken from different populations of the species. Key words: age–length key, bias, Pacific ocean perch, Sebastes alutus

Frequency distribution of Wuchereria bancrofti microfilariae in human populations and its relationships with age and sex

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 429-434 ◽  
Author(s):  
P. K. Das ◽  
A. Manoharan ◽  
A. Srividya ◽  
B. T. Grenfell ◽  
D. A. P. Bundy ◽  
...  
Keyword(s):  
Frequency Distribution ◽  
Negative Binomial ◽  
Age Distribution ◽  
Indirect Evidence ◽  
Wuchereria Bancrofti ◽  
Parameter Estimates ◽  
Human Populations ◽  
Sampling Errors ◽  
Frequency Distributions ◽  
Age And Sex

SUMMARYThis paper examines the effects of host age and sex on the frequency distribution of Wuchereria bancrofti infections in the human host. Microfilarial counts from a large data base on the epidemiology of bancroftian filariasis in Pondicherry, South India are analysed. Frequency distributions of microfilarial counts divided by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. Parameter estimates from the fits indicate a significant trend of decreasing overdispersion with age in the distributions above age 10; this pattern provides indirect evidence for the operation of density-dependent constraints on microfilarial intensity. The analysis also provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors (around 5% of the total negatives). This allows the construction of corrected mf age–prevalence curves, which indicate that the observed prevalence may underestimate the true figures by between 25% and 100%. The age distribution of mf-negative individuals in the population is discussed in terms of current hypotheses about the interaction between disease and infection.

Frequency distribution of space groups in soluble and membrane proteins and their complexes

2021 ◽  
Vol 77 (6) ◽  
pp. 187-191
Author(s):  
Rajneesh K. Gaur
Keyword(s):  
Membrane Proteins ◽  
Frequency Distribution ◽  
Data Bank ◽  
Frequency Distributions ◽  
Space Group ◽  
Space Groups ◽  
Group Frequency ◽  
Different Types ◽  
Analytical Assessment ◽  
Three Space

The space-group frequency distributions for two types of proteins and their complexes are explored. Based on the incremental availability of data in the Protein Data Bank, an analytical assessment shows a preferential distribution of three space groups, i.e. P212121 > P1211 > C121, in soluble and membrane proteins as well as in their complexes. In membrane proteins, the order of the three space groups is P212121 > C121 > P1211. The distribution of these space groups also shows the same pattern whether a protein crystallizes with a monomer or an oligomer in the asymmetric unit. The results also indicate that the sizes of the two entities in the structures of soluble proteins crystallized as complexes do not influence the frequency distribution of space groups. In general, it can be concluded that the space-group frequency distribution is homogenous across different types of proteins and their complexes.

scholarly journals Regional parent flood frequency distributions in Europe – Part 1: Is the GEV model suitable as a pan-European parent?

2014 ◽  
Vol 18 (11) ◽  
pp. 4381-4389 ◽  
Author(s):  
J. L. Salinas ◽  
A. Castellarin ◽  
A. Viglione ◽  
S. Kohnová ◽  
T. R. Kjeldsen
Keyword(s):  
Statistical Model ◽  
Frequency Distribution ◽  
Climatic Factors ◽  
Extreme Value ◽  
Flood Frequency ◽  
Generalized Extreme Value Distribution ◽  
Statistical Hypothesis ◽  
Generalized Extreme Value ◽  
Frequency Distributions ◽  
Hypothetical Scenario

Abstract. This study addresses the question of the existence of a parent flood frequency distribution on a European scale. A new database of L-moment ratios of flood annual maximum series (AMS) from 4105 catchments was compiled by joining 13 national data sets. Simple exploration of the database presents the generalized extreme value (GEV) distribution as a potential pan-European flood frequency distribution, being the three-parameter statistical model that with the closest resemblance to the estimated average of the sample L-moment ratios. Additional Monte Carlo simulations show that the variability in terms of sample skewness and kurtosis present in the data is larger than in a hypothetical scenario where all the samples were drawn from a GEV model. Overall, the generalized extreme value distribution fails to represent the kurtosis dispersion, especially for the longer sample lengths and medium to high skewness values, and therefore may be rejected in a statistical hypothesis testing framework as a single pan-European parent distribution for annual flood maxima. The results presented in this paper suggest that one single statistical model may not be able to fit the entire variety of flood processes present at a European scale, and presents an opportunity to further investigate the catchment and climatic factors controlling European flood regimes and their effects on the underlying flood frequency distributions.

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