scholarly journals Scaling in the growth of geographically subdivided populations: invariant patterns from a continent-wide biological survey

2002 ◽  
Vol 357 (1421) ◽  
pp. 627-633 ◽  
Author(s):  
Timothy H. Keitt ◽  
Luis A. N. Amaral ◽  
Sergey V. Buldyrev ◽  
H. Eugene Stanley
Keyword(s):  
Growth Rates ◽  
Scaling Laws ◽  
Total Population ◽  
Breeding Birds ◽  
Population Growth Rates ◽  
Biological Survey ◽  
Subdivided Population ◽  
Subdivided Populations ◽  
Power Law Function ◽  
The Relationship

We consider statistical patterns of variation in growth rates for over 400 species of breeding birds across North America surveyed from 1966 to 1998. We report two results. First, the standard deviation of population growth rates decays as a power–law function of total population size with an exponent β = 0.36 ± 0.02. Second, the number of subpopulations, measured as the number of survey locations with non–zero counts, scales to the 3/4 power of total number of birds counted in a given species. We show how these patterns may be related, and discuss a simple stochastic growth model for a geographically subdivided population that formalizes the relationship. We also examine reasons that may explain why some species deviate from these scaling laws.

The dynamics and conservation of a spatially subdivided avian population in a fragmented landscape

2002 ◽  
Vol 8 (3) ◽  
pp. 159 ◽  
Author(s):  
Gary W. Luck
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Agricultural Landscape ◽  
Local Population ◽  
Bird Species ◽  
Fragmented Landscape ◽  
Population Growth Rates ◽  
Local Populations ◽  
Subdivided Population ◽  
Subdivided Populations

Many bird species have declined in abundance in the agricultural regions of southern Australia, The mechanisms underlying these declines and the viability of the remaining populations are largely unknown, A number of species exist as spatially subdivided populations in heavily fragmented landscapes. Metapopulation and source-sink theory have influenced thinking on the dynamics of subdivided populations, but the general applicability of these theories is uncertain. I examined the dynamics of a subdivided population of the Rufous Treecreeper Climacteris ruta, a declining woodland passerine, occupying a fragmented, agricultural landscape in southwestern Australia. I determined if local populations could replace themselves without immigration and estimated population growth rates for the periods 1998-1999 and 1999-2000. I also examined the influence of movement between local populations on the viability of the entire subdivided population. Out of four geographically defined local populations, only one was above replacement, and only in one year of the study. Fledgling productivity and recruitment in the remainder were not sufficient to compensate for breeding female mortality. Long-term population growth estimates were <1 for all local populations, but variability in demographic rates suggested that the status of these populations may fluctuate over time. Also, there appeared to be sufficient movement between local populations, and into the study area from nearby habitat remnants, to slow or halt any decline in local population size, Within- and between-local-population processes appeared to be important to the viability of the treecreeper population during the two years of the study, and this is consistent with the general principles of metapopulation theory. I compared the dynamics of the treecreeper population occupying the fragmented landscape with one occupying a continuously wooded landscape and found that the latter had population growth rates >1, suggesting it may be an important population source and vital to the regional viability of the species.

scholarly journals Trait dimensionality explains widespread variation in local adaptation

2015 ◽  
Vol 282 (1802) ◽  
pp. 20141570 ◽  
Author(s):  
Ailene MacPherson ◽  
Paul A. Hohenlohe ◽  
Scott L. Nuismer
Keyword(s):  
Gene Flow ◽  
Local Adaptation ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Strong Correlation ◽  
Empirical Support ◽  
Reciprocal Transplant ◽  
Population Growth Rates ◽  
Using Data ◽  
The Relationship

All species are locked in a continual struggle to adapt to local ecological conditions. In cases where species fail to locally adapt, they face reduced population growth rates, or even local extinction. Traditional explanations for limited local adaptation focus on maladaptive gene flow or homogeneous environmental conditions. These classical explanations have, however, failed to explain variation in the magnitude of local adaptation observed across taxa. Here we show that variable levels of local adaptation are better explained by trait dimensionality. First, we develop and analyse mathematical models that predict levels of local adaptation will increase with the number of traits experiencing spatially variable selection. Next, we test this prediction by estimating the relationship between dimensionality and local adaptation using data from 35 published reciprocal transplant studies. This analysis reveals a strong correlation between dimensionality and degree of local adaptation, and thus provides empirical support for the predictions of our model.

Relationship between body size and population growth rate in two opportunistic polychaetes

2002 ◽  
Vol 82 (3) ◽  
pp. 403-408 ◽  
Author(s):  
D. Prevedelli ◽  
R. Simonini
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Sex Ratio ◽  
Population Growth ◽  
Growth Rates ◽  
Life Histories ◽  
Population Growth Rate ◽  
Population Growth Rates ◽  
The Relationship ◽  
Dinophilus Gyrociliatus

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.

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

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.

Career Adaptability and Career Decision Self-Efficacy: Meta-Analysis

2021 ◽  
pp. 089484532110124
Author(s):  
Graham B. Stead ◽  
Lindsey M. LaVeck ◽  
Sandra M. Hurtado Rúa
Keyword(s):  
Self Efficacy ◽  
Total Population ◽  
Meta Analysis ◽  
Career Decision ◽  
Decision Making Process ◽  
Career Adaptability ◽  
Efficacy Measures ◽  
Meta Analyses ◽  
Career Research ◽  
The Relationship

The relationship between career adaptability and career decision self-efficacy was examined due to its importance for clients in the career development and career decision-making process. Multivariate meta-analyses using 18 studies with a total population of 6,339 participants were employed. Moderator variables important to this relationship were country of participants, mean age, and career adaptability measures. Estimated correlations between career adaptability subscales and career decision self-efficacy measures ranged from .36 to .44. Findings are discussed in relation to career research and counseling.

scholarly journals Does Revitalizing the Center of Mid-Sized French Cities Reduce GHG Emissions from Commuting?

2021 ◽  
Vol 13 (4) ◽  
pp. 1851
Author(s):  
Alexis Poulhès ◽  
Angèle Brachet
Keyword(s):  
Land Use Planning ◽  
Statistical Models ◽  
Total Population ◽  
Ghg Emissions ◽  
Low Carbon ◽  
Trip Distance ◽  
Working People ◽  
Shrinking City ◽  
The Relationship ◽  
Positive Effect

Mid-sized cities are usually considered in the literature to be shrinking cities. Some policies promote right-sizing and others promote revitalization. The relationship between land-use planning and mobility having been established, the present research issue is focused on whether a policy of revitalizing the centers of mid-sized cities is favorable to low-carbon mobility. Our study investigates commuting trips through two indicators: commuting trip distance and car modal share. The increase in total population, the increase in the number of jobs per resident, the decrease in the unemployment rate, the increase in the rate of executives, the increase in the rate of working people in the population and the decrease in the residential vacancy rate all come from the censuses of 2006 and 2016. Statistical models based on individuals in 113 mid-sized cities, in which sociodemographic variables are introduced, show that at the level of agglomerations, no indicator has a simultaneously positive effect in the center and in the urban periphery. No indicator is entirely positive or negative on GHG emissions from commuting trips. While the increase in GHG emissions from commuting trips between 2006 and 2016 is significant in mid-sized cities (18%), a shift toward shrinking city centers is insufficient to change this trajectory.

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