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Population growth and development of two species of Cladocera, Moina micrura and Diaphanosoma birgei, in laboratory

SIPAÚBA-TAVARES, L. H.; BACHION, M. A.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: 701-711
ENG
Relevância na Pesquisa
65.8%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); O objetivo do presente trabalho foi testar a influência de quatro dietas alimentares sobre o crescimento populacional, desenvolvimento, comprimento total, peso seco e valor nutricional de duas espécies zooplanctônicas, Moina micrura and Diaphanosoma birgei, com os seguintes tratamentos alimentares: somente alga (A), alga + vitaminas (AV), alga + ração (AR) e alga + ração + vitaminas (ARV). O pico de crescimento para as duas espécies estudadas ocorreu mais rápido no tratamento AV. em geral, o tratamento AV para M. micrura mostrou melhores resultados para taxa intrínseca, fecundidade, desenvolvimento embrionário e pós-embrionário. Já a longevidade e número total de desovas apresentaram melhores resultados no tratamento AR (p < 0,05). Para D. birgei, os melhores resultados foram obtidos nos tratamentos contendo ração e vitamina (p < 0,05). A maior porcentagem de proteínas e lipídeos para os dois cladóceros ocorreu nos tratamentos contendo ração, já o carboidrato foi maior no tratamento contendo somente alga (p < 0,05). em geral, as dietas contendo ração e vitamina apresentaram os melhores resultados para o desenvolvimento dos cladóceros...

Population growth in random environments: which stochastic calculus?

Braumann, Carlos A.
Fonte: International Statistical Institute Publicador: International Statistical Institute
Tipo: Parte de Livro Formato: 100404 bytes; application/pdf
ENG
Relevância na Pesquisa
65.77%
Refereed scientific paper on stochastic differential equation models of population growth in random environments with resolution of the controversy on the use of Itô or Stratonovich calculus (extension to density-dependent noise intensities). The paper is in press in the Bulletin of ISI containing the Proceedings of the 56th Session of the ISI (2007). An electronic version is available.

Environmental vs Demographic Stochasticity in Population Growth

Braumann, C. A.
Fonte: Springer Publicador: Springer
Tipo: Parte de Livro Formato: 682247 bytes; application/pdf
ENG
Relevância na Pesquisa
65.82%
Compares the effect on population growth of envinonmental stochasticity (random environmental variations described by stochastic differential equations) with demographic stochasticity (random variations in births and deaths described by branching processes and birth-and-death processes), in the density-independent and the density-dependent cases.

Population growth and development of two species of Cladocera, Moina micrura and Diaphanosoma birgei, in laboratory

SIPAÚBA-TAVARES,L. H.; BACHION,M. A.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2002 EN
Relevância na Pesquisa
65.8%
The objective of the present work was to investigate the influence of four diets on population growth, development, total length, dry weight, and nutritional value of two zooplanktonic species, Moina micrura and Diaphanosoma birgei. The four dietary treatments were: algae alone (A); algae + vitamins (AV); algae + ration (AR); and algae + ration + vitamins (ARV). Growth rate peak for both species occurred faster with AV treatment. In general, AV treatment for M. micrura showed better results for intrinsic rate, fecundity, and embryonic and post-embryonic development. On the other hand, longevity and total spawning number were better with AR treatment (p < 0.05). Vitamin and ration treatments produced the best results in D. birgei species (p < 0.05). The highest percentage of protein and lipids for both cladocerans was verified for ration treatments. Carbohydrate was higher for the treatment containing algae alone (p < 0.05). Generally, diets containing ration and vitamin showed better results in cladocerans development, with water quality adequate for culture systems. Ration and vitamin diets may also be used in high-density cultures in the laboratory.

Development and population growth of Hydra viridissima Pallas, 1766 (Cnidaria, Hydrozoa) in the laboratory

Massaro,FC.; Rocha,O.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2008 EN
Relevância na Pesquisa
65.9%
Hydras, the most representative freshwater Cnidaria, are of common occurrence in bodies of water in every continent except Antarctica. This study was planned with the aim of maintaining a population of Hydra viridissima in laboratory culture to enable the determination of the individual and population growth-rates of this species, as well as its population doubling time and generation time, with a view to employing these common animals as test-organisms in ecotoxicological assays. The organisms were maintained in reconstituted water at 20 ± 2 °C, illuminated at 800 lux with a photoperiod of 12 hours light: 12 hours dark, and were fed on neonates of the cladoceran Ceriodaphnia silvestrii (3 or 4 neonates per hydra, 3 times a week). The individual growth-rate (k) of the species was 0.43, the maximum length of the column 2.53 mm and the generation time 6.6 ± 1.5 days on average. The hydra population showed an intrinsic growth-rate (r) of 0.0468, according to the fitted curve, and a doubling time of 14.8 ± 2.63 days. Hydra viridissima is easy to grow in the laboratory and performs well in the conditions used in this study. It is thus a promising candidate test-organism for ecotoxicological studies.

Low Schooling for Girls, Slower Growth for All? Cross-Country Evidence on the Effect of Gender Inequality in Education on Economic Development

Klasen, Stephan
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
56.01%
Using cross-country and panel regressions, this article investigates how gender inequality in education affects long-term economic growth. Such inequality is found to have an effect on economic growth that is robust to changes in specifications and controls for potential endogeneities. The results suggest that gender inequality in education directly affects economic growth by lowering the average level of human capital. In addition, growth is indirectly affected through the impact of gender inequality on investment and population growth. Some 0.4-0.9 percentage points of differences in annual per capita growth rates between East Asia and Sub-Saharan Africa, South Asia, and the Middle East can be accounted for by differences in gender gaps in education between these regions.

Population, Poverty, and Climate Change

Das Gupta, Monica
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
56.02%
The literature is reviewed on the relationships between population, poverty, and climate change. While developed countries are largely responsible for global warming, the brunt of the fallout will be borne by the developing world, in lower agricultural output, poorer health, and more frequent natural disasters. Carbon emissions in the developed world have leveled off, but are projected to rise rapidly in the developing world due to their economic growth and population growth -- the latter most notably in the poorest countries. Lowering fertility has many benefits for the poorest countries. Studies indicate that, in high fertility settings, fertility decline facilitates economic growth and poverty reduction. It also reduces the pressure on livelihoods, and frees up resources to cope with climate change. And it helps avert some of the projected global warming, which will benefit these countries far more than those that lie at higher latitudes and/or have more resources to cope with climate change. Natural experiments indicate that family planning programs are effective in helping reduce fertility...

Policy Note on Population Growth and its Implications in Timor-Leste

World Bank
Fonte: Washington, DC Publicador: Washington, DC
EN_US
Relevância na Pesquisa
66.03%
The report offers a description of current demographics, including density, population structure, and the components of population change. It explains projection procedures and provides results, including some alternative projections. The report assesses consequences of population growth for key sectors of society such as education and employment and offers options for modifying future population trends, focusing on high fertility and the reasons behind it. A brief discussion of the health sector highlights problems of promoting family planning. Comparisons are made where appropriate with other developing countries, particularly within Southeast Asia.

Recent technological and economic change among industrialized countries: insights from population growth

Beaudry, P.; Collard, F.
Fonte: Blackwell Publ Ltd Publicador: Blackwell Publ Ltd
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
Relevância na Pesquisa
65.91%
Cross‐country observations on the effects of population growth are used to show why differences in rates of growth in working‐age population may be a key to understanding differences in economic performance across industrialized countries over the period 1975–1997 versus 1960–1974. In particular, we argue that countries with lower rates of adult population growth adopted new capital‐intensive technologies more quickly than their high population growth counterparts, therefore allowing them to reduce their work time without deterioration of growth in output‐per‐adult.

Reconstructing the dynamics of ancient human populations from radiocarbon dates: 10 000 years of population growth in Australia

Johnson, C.; Brook, B.
Fonte: Royal Soc London Publicador: Royal Soc London
Tipo: Artigo de Revista Científica
Publicado em //2011 EN
Relevância na Pesquisa
65.88%
Measuring trends in the size of prehistoric populations is fundamental to our understanding of the demography of ancient people and their responses to environmental change. Archaeologists commonly use the temporal distribution of radiocarbon dates to reconstruct population trends, but this can give a false picture of population growth because of the loss of evidence from older sites. We demonstrate a method for quantifying this bias, and we use it to test for population growth through the Holocene of Australia. We used model simulations to show how turnover of site occupation across an archaeological landscape, interacting with erasure of evidence at abandoned sites, can create an increase in apparent site occupation towards the present when occupation density is actually constant. By estimating the probabilities of abandonment and erasure from archaeological data, we then used the model to show that this effect does not account for the observed increase in occupation through the Holocene in Australia. This is best explained by population growth, which was low for the first part of the Holocene but accelerated about 5000 years ago. Our results provide new evidence for the dynamism of non-agricultural populations through the Holocene.; Christopher N. Johnson and Barry W. Brook

Is Population Growth Conducive to the Sustainability of Cooperation?

Stark, Oded; Jakubek, Marcin
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: ResearchPaper
EN
Relevância na Pesquisa
65.82%
This paper asks whether population growth is conducive to the sustainability of cooperation. A simple model is developed in which farmers who live around a circular lake engage in trade with their adjacent neighbors. The payoffs from this activity are governed by a prisoner’s dilemma “rule of engagement.” Every farmer has one son when the population is not growing, or two sons when it is growing. In the former case, the son takes over the farm when his father dies. In the latter case, one son stays on his father’s farm, whereas the other son settles around another lake, along with the “other” sons of the other farmers. During his childhood, each son observes the strategies and the payoffs of his father and of the trading partners of his father, and imitates the most successful strategy when starting farming on his own. Then mutant defectors are introduced into an all-cooperator community. The defector strategy may spread. A comparison is drawn between the impact in terms of the sustainability of cooperation of the appearance of the mutants in a population that is not growing, and in one that is growing. It is shown that the ex-ante probability of sustaining the cooperation strategy is higher for a community that is growing than for a stagnant community.

Climate change and population growth: Australia's diabolical equation

Walters, Joe
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Relatório
Relevância na Pesquisa
56.01%
The purpose of this report is to provide an overview of the relationship between population and climate change, and explore the viability of stabilising population levels as a means of mitigating Australia's future carbon emissions. The aim of the report was to provide to Mr Kelvin Thomson MP, the most useful discussion of the relationship between population and climate change in Australia, and the effect of population growth on the Government's greenhouse gas (GHG) mitigation target. The analysis was based on appraising the future direction of Australia's population and emissions growth, examining the drivers of this growth, comparing methods for limiting the growth of both, and evaluating the likely impacts of these methods. Chapter I finds that immigration policy is the method by which the Australian Government can most influence future population. However, the formation of immigration policy, and thus population growth, has been influenced by interest groups that often have considerable national profiles, and often with conflicting agendas, and this factor has heavily influenced the creation of long-term policy. Chapter IT finds that Australia's GHG emissions are extremely high per capita and largely driven by substantial growth in stationary energy. Australia's GHG emissions will be abated...

Population, Poverty, and Sustainable Development : A Review of the Evidence

Das Gupta, Monica; Bongaarts, John; Cleland, John
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
ENGLISH
Relevância na Pesquisa
56.04%
There is a very large but scattered literature debating the economic implications of high fertility. This paper reviews the literature on three themes: (a) Does high fertility affect low-income countries' prospects for economic growth and poverty reduction? (b) Does population growth exacerbate pressure on natural resources? and (c) Are family planning programs effective at lowering fertility, and should they be publicly funded? The literature shows broad consensus that while policy and institutional settings are key in shaping the prospects of economic growth and poverty reduction, the rate of population growth also matters. Recent studies find that low dependency ratios (as fertility declines) create an opportunity for increasing productivity, savings and investment in future growth. They find that lower fertility is associated with better child health and schooling, and better health and greater labor-force participation for women. They also indicate that rapid population growth can constrain economic growth...

The impact of disease on the survival and population growth rate of the Tasmanian devil

Lachish, Shelly; Jones, Menna E; McCallum, Hamish
Fonte: British Ecological Society Publicador: British Ecological Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.9%
1. We investigated the impact of a recently emerged disease, Devil Facial Tumour Disease (DFTD), on the survival and population growth rate of a population of Tasmanian devils, Sarcophilus harrisii, on the Freycinet Peninsula in eastern Tasmania. 2. Corma

Historical Population Estimates: Unraveling the Consensus

Caldwell, John; Schindlmayr, Thomas
Fonte: Population Council Publicador: Population Council
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.83%
The mid-twentieth century witnessed the emergence of a remarkable consensus on quantitative estimates of world population growth after 1650. This was the achievement of Walter Willcox, supported and modified by Alexander Carr-Saunders and John Durand, and was endorsed by United Nations publications. It had its origin in eighteenth- and nineteenth-century work, largely carried out in Germany. Willcox was particularly interested in demonstrating seventeenth-century population growth as evidence of the global impact of European expansion, and this probably led to a too-ready acceptance of estimates with little real basis. More recent estimates do little to shake the consensus, but extend the historical series back over two millennia or further. The article examines the strength and influence of a consensus based in the earlier period on surprisingly insecure data. It then turns to the most suspect element in the consensus, the pre-twentieth-century estimates for Africa. Finally, little hope is expressed that future researchers will be able to establish reliable estimates, especially for dates earlier than the eighteenth century.

Age-structured population growth rates in constant and variable environments: a near equilibrium approach

Dewi, Sonya; Chesson, Peter
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.86%
General measures summarizing the shapes of mortality and fecundity schedules are proposed. These measures are derived from moments of probability distributions related to mortality and fecundity schedules. Like moments, these measures form infinite sequences, but the first terms of these sequences are of particular value in approximating the long-term growth rate of an age- structured population that is growing slowly. Higher order terms are needed for approximating faster growing populations. These approximations offer a general nonparametric approach to the study of life-history evolution in both constant and variable environments. These techniques provide simple quantitative representations of the classical findings that, with fixed expected lifetime and net reproductive rate, type I mortality and early peak reproduction increase the absolute magnitude of the population growth rate, while type III mortality and delayed peak reproduction reduce this absolute magnitude.

HERBICIDE RESISTANT WEED MANAGEMENT USING SENSITIVITY ANALYSIS OF THE WEED POPULATION GROWTH CURVE

VIDAL, RIBAS ANTÔNIO; Universidade Federal do Rio Grande do Sul; LAMEGO, FABIANE PINTO; Universidade Federal de Santa Maria; TREZZI, MICHELÂNGELO MUZELL; Universidade Tecnológica Federal do Paraná; DE PRADO, RAFAEL; Universidad de Córdoba; BURGOS, NI
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 03/01/2011 POR
Relevância na Pesquisa
65.91%
Strategies to prevent herbicide weed resistance are rarely practiced by farmers. As a consequence, herbicide resistant weed biotypes (HRWB) have been increasing worldwide in the past decades. This paper aims to analyze the weed population growth curve and to propose a strategic plan for prevention and management of HRWB. The existing weed control methods are organized considering the sensitivity analysis of the population growth at each phase of the logistic growth curve. This analysis indicates that tactics directed to reduce the population growth rate are most appropriate for HRWB management, mainly at the initial phase of the resistant weed population growth. This epidemiological approach provides evidence to the importance of early detection and management of HRWB.

Combined effect of concentrations of algal food (Chlorella vulgaris) and salt (sodium chloride) on the population growth of Brachionus calyciflorus and Brachionus patulus (Rotifera)

Peredo-Álvarez,Víctor M.; Sarma,S.S.S.; Nandini,S.
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2003 EN
Relevância na Pesquisa
65.87%
Salinity is an important variable influencing the density and diversity of rotifers. Studies on salt tolerance of rotifers have so far concentrated on euryhaline species while very little information is available on noneuryhaline taxa. In the present work, we have evaluated the combined effects of Chlorella vulgaris and sodium chloride on the population growth of two freshwater rotifers B. calyciflorus and B. patulus. A 24 hr acute tolerance test using NaCl revealed that B. calyciflorus was more resistant (LC50 = 3.75 ± 0.04 g l-1 ) than B. patulus (2.14 ± 0.09 g l-1 ). The maximal population density (mean±standard error) for B. calyciflorus in the control at 4.5 X10 6 cells ml-1 (algal level) was 80 ±5 ind. ml-1 , which was nearly a fifth of the one for B. patulus (397 ± 7 ind. ml-1 ) under comparable conditions. Data on population growth revealed that regardless of salt concentration, the density of B. calyciflorus increased with increasing food levels, while for B. patulus, this trend was evident only in the controls. Regardless of salt concentration and algal food level, the day of maximal population density was lower (4 ± 0.5 days) for B. calyciflorus than for B. patulus (11 ±1 day). The highest rates of population increase (r values) for B. calyciflorus and B. patulus were 0.429 ± 0.012 and 0.367 ± 0.004...

Effect of different densities of live and dead Chlorella vulgaris on the population growth of rotifers Brachionus calyciflorus and Brachionus patulus (Rotifera)

Lucía-Pavón,E.; Sarma,S.S.S.; Nandini,S.
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2001 EN
Relevância na Pesquisa
65.85%
In order to maintain rotifer populations during periods of low algal production, it is necessary to offer alternate diets, some of which include forms of preserved algae. The present work is based on the effect of live and dead Chlorella vulgaris on the population growth of Brachionus calyciflorus and Brachionus patulus. The experimental design consisted of 3 algal levels (0.5x10(6), 1.5x10(6) and 4.5x10(6) cells ml-1) offered in 3 forms (living, frozen and heat-killed). The maximal population density values for B. calyciflorus ranged from 55±1 ind. ml-1 (at 0.5x10(6) cells ml-1) to 471±72 ind. ml-1 (at 4.5x10(6) cells ml-1) with live Chlorella, but was much lower (6±1 to 26±6 ind. ml-1) with frozen or heat-killed alga under comparable food levels. However, the maximum population density of B. patulus under live or or heat-killed Chlorella was similar at comparable algal levels but when offered frozen algae it was four times less. The highest mean peak population density was 1227±83 ind. ml-1 under 4.5x10(6) cells ml-1. The rate of population increase for B. calyciflorus varied from 0.50 to 0.79 using live Chlorella, but under comparable conditions, this range was lower (0.21 to 0.31) for B. patulus. Results have been discussed in light of possible application for aquaculture

Effect of three food types on the population growth of Brachionus calyciflorus and Brachionus patulus (Rotifera: Brachionidae)

Sarma,S.S.S.; Larios Jurado,Paula Susana; Nandini,S.
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2001 EN
Relevância na Pesquisa
65.88%
We compared the population growth of B. calyciflorus and B. patulus using the green alga Chlorella vulgaris, baker’s yeast Saccharomyces cerevisiae or their mixture in equal proportions as food. Food was offered once every 24 h in two concentrations (low: 1x10(6) and high: 3x10(6) ind. ml-1) separately for each species. The experiments were terminated after 15 days. In general, at any food type or concentration, B. patulus reached a higher population density. A diet of Chlorella alone supported a higher population growth of both rotifer species than yeast alone. B. calyciflorus and B. patulus achieved highest population densities (103+8 ind. ml-1 and 296+20 ind. ml-1, respectively) on a diet of Chlorella at 3x10(6) ind. ml-1. When cultured using the mixture of Chlorella and yeast, the maximal population densities of B. calyciflorus were lower than those grown on Chlorella. Under similar conditions, the maximal abundance values of B. patulus were comparable in both food types. Regardless of food type and density the rate of population increase per day (r) for B. calyciflorus varied from 0.13+0.03 to 0.63+0.04. These values for B. patulus ranged from 0.19+0.01 to 0.37+0.01. The results indicated that even though Chlorella was a superior foof for the tested rotifers...