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.

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.

High Reproductive Effort and Low Recruitment Rates of European Beech: Is There a Limit for the Superior Competitor?

2015 ◽  
Vol 63 (2) ◽  
pp. 198-212 ◽  
Author(s):  
Jerzy Szwagrzyk ◽  
Georg Gratzer ◽  
Hanna Stępniewska ◽  
Janusz Szewczyk ◽  
Bojana Veselinovic
Keyword(s):  
Reproductive Effort ◽  
European Beech ◽  
High Reproductive Effort

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

Biology of Acacia pulchella R.br. With Special Reference to Symbiotic Nitrogen Fixation

1981 ◽  
Vol 29 (5) ◽  
pp. 579 ◽  
Author(s):  
D Monk ◽  
JS Pate ◽  
WA Loneragan
Keyword(s):  
Plant Density ◽  
Natural Populations ◽  
Growth Period ◽  
Sand Culture ◽  
Nitrogen And Phosphorus ◽  
N Accumulation ◽  
Growing Seasons ◽  
Reduction Activity ◽  
C2h2 Reduction ◽  
Total Plant

Growth, reproduction and longevity of the fire weed Acacia pulchella var. glaberrima were examined in natural populations of known age in coastal sands in and around Perth, W.A. Dense populations (10000 plantsiha) were established after a summer burn; plant density was 30% of its initial value at 4 years. less than 8% at 13 years. Plants accumulated dry matter, nitrogen and phosphorus throughout a 13-year growth period. Seed production commenced at 2 years, reached a maximum (12000 seeds per plant per year) at 3 or 4 years declining to 2000 seedsiplant in the 13th year. Only a small fraction of the shed seed accumulated in soil under the stands. Changes in total plant N, nodule weightlplant, and C2H2 reduction capacity of detached nodules were followed in populations in their first, second and fourth growing seasons. A new set of nodules formed with the autumn rains, peak nodule mass and C2H2 reduction activity were recorded in July-October, and virtually no nodules survived the summer into a second growing season. A glasshouse study of N accumulation and C2H2 reduction by nodules in minus N sand culture gave acalibration value of 2.26 mol C2H2 : mol N2 fixed. Applying this value to data from nativepopulations, 8% of the N accumulated by first season plants, 45% of the N of second season plants and 68% of the N of fourth season plants were estimated to be derived from symbiosis. Average annual returns of N to the ecosystem were estimated at 3.9 kg/ha, probably more than half of this from N2 fixation. Progressive death of plants in the populations gave the greatest return ( 1.9 kg N per ha per yr), the remainder from litter (1 kg N per ha per yr) and shed seed ( 1 kg N per ha per yr).

Vegetative Propagation of Species of Genus Allium L.

1993 ◽  
Vol 27 (7-8) ◽  
pp. 511-517
Author(s):  
Rina Kamenetsky
Keyword(s):  
Life Cycle ◽  
Vegetative Propagation ◽  
Genetic Stability ◽  
Vegetative Reproduction ◽  
Natural Populations ◽  
Morphological Type ◽  
Useful Plants ◽  
Allium Species ◽  
Apical Buds ◽  
Arid Conditions

The genus Allium L. consists of about 500 species in the Northern hemisphere and includes a large number of useful plants. The highly variable underground organs of Allium species - rhizomes and bulbs - have the function of storing food and moisture in severe environmental conditions. Their other very important function - vegetative reproduction and propagation - increases the chances of survival and supports the genetic stability of natural populations. Among about 40 species studied, 5 types of vegetative reproduction and propagation are distinguishable. The formation of apical buds, daughter bulblets, stolons and apomictic bulblets in the inflorescense have been observed. There is possibly some connection between vegetative propagation, morphological type and life cycle. The process of evolution within the genus and the migration of species to arid conditions lead possibly to the appearance in phylogenesis of prevalence of seminal reproduction over vegetative propagation.

Effects of thinning and nitrogen fertilization on growth of Scots pine trees: total annual biomass increment, needle efficiency, and aboveground allocation of biomass increment

1993 ◽  
Vol 23 (8) ◽  
pp. 1639-1644 ◽  
Author(s):  
Erik Valinger
Keyword(s):  
Scots Pine ◽  
Nitrogen Fertilization ◽  
Aboveground Biomass ◽  
Dry Matter ◽  
Dry Matter Production ◽  
Allocation Pattern ◽  
Biomass Increment ◽  
Matter Production ◽  
Aboveground Production ◽  
Annual Biomass

The effects of thinning and nitrogen fertilization, singly and in combination, on growth of 45-year-old Scots pine (Pinussylvestris L.) trees in northern Sweden were examined for 5 years after treatment. Annual examination of trees determined height growth, diameter growth, crown development, annual biomass increment, aboveground biomass allocation, and needle efficiency in relation to treatments. Nitrogen fertilization increased total dry matter production. The combination of thinning and nitrogen fertilization increased total dry matter production per tree more than the additive effects of thinning and nitrogen fertilization singly. Dry matter production per hectare was increased by nitrogen fertilization. Needle efficiency, i.e., total annual aboveground biomass production per unit of needle mass, was also increased by nitrogen fertilization. The increased aboveground production after nitrogen fertilization resulted from both an increase in biomass of needles and from the increased needle efficiency. The allocation pattern indicated that an increased production of stemwood was a result of a larger biomass of needles. An increase in cone production of the control trees was associated with a decrease in needle efficiency.

Biomass and nutrient allocation patterns in Jerusalem artichoke (Helianthus tuberosus)

1989 ◽  
Vol 67 (10) ◽  
pp. 2880-2887 ◽  
Author(s):  
C. J. Swanton ◽  
P. B. Cavers
Keyword(s):  
Jerusalem Artichoke ◽  
Reproductive Organs ◽  
Lateral Spread ◽  
Nutrient Allocation ◽  
Helianthus Tuberosus ◽  
Allocation Pattern ◽  
Plant Parts ◽  
Growing Seasons ◽  
Allocation Patterns ◽  
Cultivated Populations

The partitioning of dry matter and nutrients into component plant parts was determined for a weedy population of Jerusalem artichoke (Helianthus tuberosus L.). The annual allocation pattern, studied over two growing seasons, was characterized by a relatively large distribution of energy to structural increases in height, leaf number, and lateral spread. Biomass and nutrient allocation to clonal growth (rhizomes and tubers) was much greater than to reproductive organs (flowers and seeds). Reproductive and clonal allocation of nutrients showed a different pattern than allocation of biomass. Plants severely defoliated by hail in 1984 redistributed available nutrients and generated new leaves. Although rhizome and tuber size and number were reduced after the hail storm, the overall strategy of Jerusalem artichoke appears to involve a constancy of nutrient allocation to clonal structures. In contrast with previous reports for cultivated populations of Jerusalem artichoke, we found that the leaves, not the stem, constituted the primary temporary sink for assimilates that were later distributed to developing rhizomes and tubers.

scholarly journals DNA profiling and assessment of genetic diversity of relict species Allium altaicum Pall. on the territory of Altai

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10674
Author(s):  
Oxana Khapilina ◽  
Olesya Raiser ◽  
Alevtina Danilova ◽  
Vladislav Shevtsov ◽  
Ainur Turzhanova ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Endangered Species ◽  
Biological Diversity ◽  
Vegetative Reproduction ◽  
Natural Populations ◽  
Mobile Genetic Elements ◽  
Ice Age ◽  
Conservation Strategy ◽  
Relict Species ◽  
Genetic Elements

Analysis of the genetic diversity of natural populations of threatened and endangered species of plants is a main aspect of conservation strategy. The endangered species Allium altaicum is a relict plant of the Ice Age and natural populations are located in extreme climatic conditions of Kazakstan’s Altai Mountains. Mobile genetic elements and other interspersed repeats are basic components of a eukaryote genome, which can activate under stress conditions and indirectly promote the survival of an organism against environmental stresses. Detections of chromosomal changes related to recombination processes of mobile genetic elements are performed by various PCR methods. These methods are based on interspersed repeat sequences and are an effective tool for research of biological diversity of plants and their variability. In our research, we used conservative sequences of tRNA primer binding sites (PBS) when initializing the retrotransposon replication as PCR primers to research the genetic diversity of 12 natural populations of A. altaicum found in various ecogeographic conditions of the Kazakhstani Altai. High efficiency of the PBS amplification method used was observed already at the intrapopulation level. Unique amplicons representative of a certain population were found at the intrapopulation level. Analysis of molecular dispersion revealed that the biodiversity of populations of mountainous and lowland A. altaicum is due to intrapopulation differences for climatic zones of habitation. This is likely conditional upon predominance of vegetative reproduction over seed reproduction in some populations. In the case of vegetative reproduction, somatic recombination related to the activity of mobile genetic elements are preserved in subsequent generations. This leads to an increase of intrapopulation genetic diversity. Thus, high genetic diversity was observed in populations such as A. altaicum located in the territory of the Kalbinskii Altai, whereas the minimum diversity was observed in the populations of the Leninororsk ecogeographic group. Distinctions between these populations were also identified depending on the areas of their distribution. Low-land and mid-mountain living environments are characterized by a great variety of shapes and plasticity. This work allowed us to obtain new genetic data on the structure of A. altaicum populations on the territory of the Kazakhstan Altai for the subsequent development of preservation and reproduction strategies for this relict species.

Different nutrient use strategies of expansive grasses Calamagrostis epigejos and Arrhenatherum elatius

Biologia ◽  
2012 ◽  
Vol 67 (4) ◽  
Author(s):  
Petr Holub ◽  
Ivan Tůma ◽  
Jaroslav Záhora ◽  
Karel Fiala
Keyword(s):  
Aboveground Biomass ◽  
Nutrient Release ◽  
Control Treatment ◽  
Grass Species ◽  
Nutrient Concentrations ◽  
Total Biomass ◽  
Growing Seasons ◽  
Nutrient Use ◽  
Calamagrostis Epigejos ◽  
Arrhenatherum Elatius

AbstractEnhanced nitrogen (N) levels accelerate expansion of Calamagrostis epigejos and Arrhenatherum elatius, highly aggressive expanders displacing original dry acidophilous grassland vegetation in the Podyjí National Park (Czech Republic). We compared the capability of Calamagrostis and Arrhenatherum under control and N enhanced treatments to (i) accumulate N and phosphorus (P) in plant tissues, (ii) remove N and P from above-ground biomass during senescence and (iii) release N and P from plant material during decomposition of fresh formed litter. In control treatment, significantly higher amounts of total biomass and fresh aboveground litter were observed in Calamagrostis than in Arrhenatherum. Contrariwise, nutrient concentrations were significantly higher (11.6–14.3 mg N g−1 and 2.3 mg P g−1) in Arrhenatherum peak aboveground biomass than in Calamagrostis (8.4–10.3 mg N g−1 and 1.6–1.7 mg P g−1). Substantial differences between species were found in resorption of nutrients, mainly P, at the ends of growing seasons. While P concentrations in Arrhenatherum fresh litter were twice and three times higher (1.6–2.5 mg P g−1) than in Calamagrostis (0.7–0.8 mg P g−1), N concentrations were nearly doubled in Arrhenatherum (13.1–15.6 mg N g−1) in comparison with Calamagrostis (7.4–8.7 mg N g−1). Thus, the nutrients (N and mainly P) were retranslocated from the aboveground biomass of Calamagrostis probably more effectively in comparison with Arrhenatherum at the end of the growing season. On the other hand, Arrhenatherum litter was decomposed faster and consequently nutrient release (mainly N and P) was higher in comparison with Calamagrostis which pointed to different growth and nutrient use strategies of studied grass species.

Sign in / Sign up

Export Citation Format

Share Document