The relationship of variable antigen expression and population growth rates inTrypanosoma brucei

The relationship between body size and population growth rate λ has been studied in two species of opportunistic polychaetes, Dinophilus gyrociliatus and Ophryotrocha labronica, which colonize harbour environments. These species exhibit a semi-continuous iteroparous reproductive strategy, are phylogenetically closely-related but differ in body size and in some aspects of their sexuality. Ophryotrocha labronica is about 4 mm in body length, displays only slight sexual dimorphism and its sex ratio is biased towards the female sex in the ratio 2:1. Dinophilus gyrociliatus is about 1 mm in length, the males are extremely small and the sex ratio is strongly biased (3:1) in favour of the females. In spite of the considerable differences in all traits of their life histories and in many demographic parameters, the growth rates of the two populations are very similar. The analyses carried out have shown that the rapid attainment of sexual maturity of D. gyrociliatus gives it an advantage that offsets the greater fecundity of O. labronica. It is very likely that the reproductive peculiarities of D. gyrociliatus help to raise the population growth rates. The ‘saving’ on the male sex achieved both by the shift of the sex ratio in favour of the females and by the reduction in the males' body size would appear to enable D. gyrociliatus to grow at the same rate as O. labronica, a larger and more fecund species.

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A Study of the Relationship Between Attitudes Towards World Population Growth and USA Population Growth

Journal of Biosocial Science ◽

10.1017/s0021932000008944 ◽

1973 ◽

Vol 5 (1) ◽

pp. 61-69

Author(s):

Larry D. Barnett

Keyword(s):

Growth Rate ◽

Population Growth ◽

Growth Rates ◽

World Population ◽

Population Growth Rates ◽

World Population Growth ◽

The Us ◽

The World ◽

The Relationship ◽

Public Opinion Polls

In the fall of 1965 and again in the fall of 1967, The Population Council sponsored nationwide public opinion polls in which questions were asked regarding whether the world and US population growth rates constituted serious problems. Both polls found the proportion of respondents viewing the world growth rate as serious (62% in 1965, 69% in 1967) to be higher than the proportion viewing the US rate as serious (54% in 1965 and 1967) (Kantner, 1968). Thus, attitudes towards world population growth and US population growth appear to be potentially independent of and not necessarily congruent with one another, but to date no examination has been made of their relationship. It is the purpose of the present study: (1) to determine the incidence of each possible combination of views towards the world and US population growth rates, and (2) to determine how individuals with a particular attitude towards one growth rate distribute themselves in terms of attitudes towards the other rate.

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Estimates of regional annual abundance and population growth rates of white sharks off central California

Biological Conservation ◽

10.1016/j.biocon.2021.109104 ◽

2021 ◽

Vol 257 ◽

pp. 109104

Author(s):

Paul E. Kanive ◽

Jay J. Rotella ◽

Taylor K. Chapple ◽

Scot D. Anderson ◽

Timothy D. White ◽

...

Keyword(s):

Population Growth ◽

Growth Rates ◽

Central California ◽

Population Growth Rates

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ATIVIDADE ACARICIDA DE ÓLEOS ESSENCIAIS SOBRE Tetranychus ludeni (Zacher) (Acari: Tetranychidae) EM DUAS CULTIVARES DE ALGODOEIRO

Nativa ◽

10.31413/nativa.v7i5.7225 ◽

2019 ◽

Vol 7 (5) ◽

pp. 469

Author(s):

Yasmin Bruna de Siqueira Bezerra ◽

José Vargas de Oliveira ◽

Taciana Keila dos Anjos Ramalho ◽

Douglas Rafael e Silva Barbosa ◽

Carlos Romero Ferreira de Oliveira ◽

...

Keyword(s):

Population Growth ◽

Essential Oils ◽

Growth Rates ◽

Ocimum Basilicum ◽

Alternative Control ◽

Population Growth Rates ◽

Colored Cotton ◽

Potential Alternative ◽

Tetranychus Ludeni ◽

Corymbia Citriodora

O presente trabalho teve como objetivo avaliar os efeitos repelentes e as taxas de crescimento populacional de óleos essenciais de Corymbia citriodora, Ocimum basilicum e Myracroduon urundeuva sobre o ácaro vermelho Tetranychus ludeni (Zacher) em algodoeiro de fibra colorida. Para o teste de repelência, óleos de Corymbia citriodora, Ocimum basilicum e Myracroduon urundeuva foram testados em diferentes concentrações sobre fêmeas adultas de T. ludeni, assim como para o teste de crescimento populacional, onde as cultivares foram tratadas com óleos essenciais. O efeito repelente foi verificado para todos os óleos testados nas duas cultivares de algodão colorida. As taxas instantâneas de crescimento populacional para T. ludeni nas cultivares de algodoeiro BRS Verde e BRS Rubi foram todas positivas (ri> 0), indicando que a população está em estado ascendente, no entanto, a população cresceu a uma taxa menor quando comparada ao controle. Os óleos essenciais de C. citriodora, O. basilicum e M. urundeuva apresentam efeito acaricida e potencial controle alternativo de T. ludeni em algodoeiro de fibras coloridas sem causar danos ao algodoeiro.Palavras-chave: ácaro vermelho; algodão colorido; controle alternativo; taxa instantânea de crescimento; repelência. ACARICIDAL ACTIVITY OF ESSENTIAL OILS ON RED MITETetranychus ludeni (Zacher) (Acari: Tetranychidae) IN TWO COTTON CULTIVARS ABSTRACT: The objective of this work was to evaluate the repellent and population growth rates of essential oils of Corymbia citriodora, Ocimum basilicum and Myracroduon urundeuva on the red mite Tetranychus ludeni (Zacher) in cotton fiber. For the repellency test, oils of Corymbia citriodora, Ocimum basilicum and Myracroduon urundeuva were tested in different concentrations on adult females of T. ludeni, as well as for the population growth test, where the cultivars were treated with essential oils. The repellent effect was verified for all tested oils the two cultivars of colored cotton. The instant population growth rates for T. ludeni in the cultivars BRS Verde and BRS Rubi were all positive (ri> 0), indicating that the population is in an upward, however, the population grew at a lower rate when compared to the control. The essential oils of C. citriodora, O. basilicum and M. urundeuva have an acaricidal effect and potential alternative control of T. ludeni in cotton from colored fibers without causing damage to the cotton.Keywords: Red mite; colored cotton; essential oils; instant growth rate; repellency.

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Population Growth - The Social Development and Poverty Dimension

THE LAHORE JOURNAL OF ECONOMICS ◽

10.35536/lje.1999.v4.i1.a3 ◽

1999 ◽

Vol 4 (1) ◽

pp. 41-52

Author(s):

M.S. Jillani

Keyword(s):

Reproductive Health ◽

Population Growth ◽

Social Development ◽

Human Health ◽

Reproductive System ◽

Social Wellbeing ◽

The Social ◽

The World ◽

Relationship Of ◽

The Relationship

The debate over the relationship of population and development is now more than 200 years old, starting with the treatise on population by Malthus, in 1798. The increase in population, ever since, has remained a matter of concern for economists and development planners. The most recent high point of the issue was witnessed at Cairo in September, 1994. The conference which was attended by more than 10,000 persons from all over the world ended with an agreement on the issues involved in the growth of population and the economy. The outcome was a Plan of Action for the next twenty years, which would concentrate on Reproductive Health in order to obtain, “a state of complete physical, mental and social wellbeing, and not merely the absence of disease or infirmity in all matters relating to the reproductive system and its functions and process”. This can be a turn-around in global efforts for human health and welfare, if properly implemented.

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An Evaluation of RNA–DNA Ratio as a Measure of Long-Term Growth in Fish Populations

Journal of the Fisheries Research Board of Canada ◽

10.1139/f73-035 ◽

1973 ◽

Vol 30 (2) ◽

pp. 195-199 ◽

Cited By ~ 69

Author(s):

Terry A. Haines

Keyword(s):

Growth Rate ◽

Population Growth ◽

Growth Rates ◽

Population Growth Rate ◽

Environmental Changes ◽

Age Distribution ◽

Smallmouth Bass ◽

Fish Populations ◽

Population Growth Rates

The value of RNA–DNA ratio as a measure of long-term growth of fish populations under semi-natural conditions and when subjected to environmental manipulations was determined. Populations of carp and smallmouth bass of known age distribution were established in artificial ponds maintained at two fertility levels. After 15 months, population growth rates (as percent increase in weight) and RNA–DNA ratios of muscle tissue from selected fish were measured. Each species exhibited a range of population growth rates. The relation between population growth rate and individual fish RNA–DNA ratio for each species was significant. When reproduction occurred, the relation was not significant unless young-of-the-year fish were excluded from population growth rate calculations. Age of fish was also found to have an important effect on RNA–DNA ratio, with the ratio being higher in younger fish.RNA–DNA ratio can be a reliable indicator of long-term population growth in fish when population age structure is known and recruitment is controlled. The method has potential for use in detecting response to environmental changes before growth rate changes become severe.

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Life history and environmental influences on population dynamics in sockeye salmon

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0326 ◽

2014 ◽

Vol 71 (8) ◽

pp. 1198-1208 ◽

Cited By ~ 4

Author(s):

Douglas C. Braun ◽

John D. Reynolds

Keyword(s):

Population Dynamics ◽

Life History ◽

Population Growth ◽

Growth Rates ◽

Environmental Conditions ◽

Sockeye Salmon ◽

Life History Traits ◽

Relative Importance ◽

Population Growth Rates ◽

Habitat Variables

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates.

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