scholarly journals Perturbation Analysis of Population Growth Rates in Taiwan

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Shun-Chieh Hsieh
Keyword(s):  
Perturbation Analysis ◽  
Census Data ◽  
Population Management ◽  
Management Policy ◽  
Demographic Parameters ◽  
Relative Importance ◽  
Vital Rates ◽  
Management Effectiveness ◽  
Substantial Impact ◽  
Population Growth Rates

The total fertility rate in Taiwan has fallen below 1.3 since 2003. The objective of the study is to use perturbation analysis with census data from 1992 to 2017 to identify which demographic parameters are most important to target for population management. The research shows that the fertility of older ages plays an important role for declining population in Taiwan. From a practical viewpoint, population management policy having a substantial impact on the survival of prereproductive females and the fertility of order females is likely to produce the most dramatic change in population trends. Therefore, the perturbation analysis is useful in understanding the relative importance of vital rates to increase management effectiveness.

scholarly journals Density-independent processes decouple component and ensemble density feedbacks

2021 ◽  
Author(s):  
Corey J. A. Bradshaw ◽  
Salvador Herrando-Perez
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Carrying Capacity ◽  
Census Data ◽  
Growth Models ◽  
Structured Populations ◽  
Logistic Growth ◽  
Feedback Signal ◽  
Vital Rates ◽  
Population Growth Rates

Analysis of long-term trends in abundance provide insights into population dynamics. Population growth rates are the emergent interplay of fertility, survival, and dispersal, but the density feedbacks on some vital rates (component) can be decoupled from density feedback on population growth rates (ensemble). However, the mechanisms responsible for this decoupling are poorly understood. We simulated component density feedbacks on survival in age-structured populations of long-living vertebrates and quantified how imposed nonstationarity (density-independent mortality and variation in carrying-capacity) modified the ensemble feedback signal estimated from logistic-growth models to the simulated abundance time series. The statistical detection of ensemble density feedback was largely unaffected by density-independent processes, but catastrophic and proportional mortality eroded the effect of density-dependent survival on ensemble-feedback strength more strongly than variation in carrying capacity. Thus, phenomenological models offer a robust approach to capture density feedbacks from nonstationary census data when density-independent mortality is low.

The Digital Divide and K-12 Student Computer Use

10.28945/2926 ◽  
2005 ◽  
Author(s):  
James N. Morgan ◽  
Craig A. VanLengen
Keyword(s):  
Digital Divide ◽  
Computer Use ◽  
Census Data ◽  
Internet Access ◽  
Demographic Characteristics ◽  
The Internet ◽  
Substantial Impact ◽  
Limited Basis ◽  
K 12 ◽  
The Impact

The divide between those who have computer and Internet access and those who do not appears to be narrowing, however overall statistics may be misleading. Measures of computer availability in schools often include cases where computers are only available for administration or are available only on a very limited basis (Gootman, 2004). Access to a computer and the Internet outside of school helps to reinforce student learning and emphasize the importance of using technology. Recent U.S. statistics indicate that ethnic background and other demographic characteristics still have substantial impact on the availability and use of computers by students outside of the classroom. This paper examines recent census data to determine the impact of the household on student computer use outside of the classroom. Encouragingly, the findings of this study suggest that use of a computer at school substantially increases the chance that a student will use a computer outside of class. Additionally, this study suggests that computer use outside of the classroom is positively and significantly impacted by being in a household with adults who either use a computer at work or work in an industry where computers are extensively used.

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Life History ◽  
Population Growth ◽  
Adult Mortality ◽  
Life History Strategies ◽  
Relative Importance ◽  
Theoretical Frameworks ◽  
Population Growth Rates ◽  
Relative Contribution ◽  
Two Populations ◽  
Average Fitness

Abstract There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations.

Management inferences from a demographic analysis of sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes

2008 ◽  
Vol 65 (2) ◽  
pp. 227-244 ◽  
Author(s):  
Luis Antonio Vélez-Espino ◽  
Robert L McLaughlin ◽  
Thomas C Pratt
Keyword(s):  
Great Lakes ◽  
Life Stage ◽  
Petromyzon Marinus ◽  
Management Strategies ◽  
Sea Lamprey ◽  
Management Plan ◽  
Laurentian Great Lakes ◽  
Alternative Methods ◽  
Vital Rates ◽  
Population Growth Rates

We use matrix models incorporating uncertainty in values of life history traits and density-dependent survival to assess pest management strategies implemented by the Great Lakes Fishery Commission to control nonnative sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes. The primary method of sea lamprey control has been treatment of rearing tributaries with chemical lampricides, but release of sterilized males and deployment of migratory barriers and traps are important components of the management plan. Uncertainties in the effectiveness of alternative control remain, however. Our models demonstrated that the management target of reducing lampricide use by 20% while maintaining current levels of control could be achieved if alternative methods are used to suppress current lake-wide fecundity rates by 49%–65%, assuming equal lampricide efficiency on larvae and metamorphosing individuals, or by 42%–55% when lampricide mortality on larvae is assumed to be half of that on metamorphosing individuals. At current levels of lampricide use, reduction to 72%–88% of current fecundity rates is recommended to ensure long-term control of sea lamprey populations in the face of uncertainty in current estimates of population growth rates. New control options targeting additional vital rates, such as survival of the parasitic life stage, could further reduce reliance on lampricides while maintaining effective sea lamprey control.

Life history and environmental influences on population dynamics in sockeye salmon

2014 ◽  
Vol 71 (8) ◽  
pp. 1198-1208 ◽  
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.

Ethnocentric Tendencies, Marketing Strategy and Import Purchase Behaviour

1994 ◽  
Vol 11 (3) ◽  
pp. 4-16 ◽  
Author(s):  
Joel Herche
Keyword(s):  
Marketing Strategy ◽  
Personal Computer ◽  
Mail Survey ◽  
Marketing Mix ◽  
Relative Importance ◽  
Substantial Impact ◽  
Future Studies ◽  
The Usa

Reports on an analysis of the relative importance of various marketing mix strategies and consumer ethnocentric tendencies in the decision to purchase imports undertaken via a nationwide mail survey of personal computer owners in the USA. The results indicate that ethnocentric tendencies are able to explain a much greater amount of variation in purchase behaviour than marketing mix variables. Concludes that the inclusion of ethnocentric tendencies into future studies on origin bias appears to be warranted given their substantial impact on import purchase behaviour.

scholarly journals Improving AfriPop dataset with settlement extents extracted from RapidEye for the border region comprising South-Africa, Swaziland and Mozambique

2015 ◽  
Vol 10 (2) ◽  
Author(s):  
Julie Deleu ◽  
Jonas Franke ◽  
Michael Gebreslasie ◽  
Catherine Linard
Keyword(s):  
South Africa ◽  
High Resolution ◽  
Census Data ◽  
Population Distribution ◽  
Malaria Incidence ◽  
Border Region ◽  
Land Use Classification ◽  
Population Growth Rates ◽  
Kwazulu Natal ◽  
Satellite Sensors

For modelling the spatial distribution of malaria incidence, accurate and detailed information on population size and distribution are of significant importance. Different, global, spatial, standard datasets of population distribution have been developed and are widely used. However, most of them are not up-to-date and the low spatial resolution of the input census data has limitations for contemporary, national- scale analyses. The AfriPop project, launched in July 2009, was initiated with the aim of producing detailed, contemporary and easily updatable population distribution datasets for the whole of Africa. High-resolution satellite sensors can help to further improve this dataset through the generation of high-resolution settlement layers at greater spatial details. In the present study, the settlement extents included in the MALAREO land use classification were used to generate an enhanced and updated version of the AfriPop dataset for the study area covering southern Mozambique, eastern Swaziland and the malarious part of KwaZulu-Natal in South Africa. Results show that it is possible to easily produce a detailed and updated population distribution dataset applying the AfriPop modelling approach with the use of high-resolution settlement layers and population growth rates. The 2007 and 2011 population datasets are freely available as a product of the MALAREO project and can be downloaded from the project website.

Characterization of elasticity patterns of North American freshwater fishes

2006 ◽  
Vol 63 (9) ◽  
pp. 2050-2066 ◽  
Author(s):  
Luis A Vélez-Espino ◽  
Michael G Fox ◽  
Robert L McLaughlin
Keyword(s):  
Population Growth ◽  
North American ◽  
Growth Rates ◽  
Freshwater Fishes ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Vital Rates ◽  
Population Growth Rates ◽  
North American Freshwater ◽  
Trade Offs

We applied elasticity analysis to 88 North American freshwater fishes to assess the relative impacts of changes in the vital rates on asymptotic population growth. Variance in vital rates was summarized for four distinct functional groups: (i) species with population growth rates strongly sensitive to perturbations in adult survival; (ii) species with population growth rates sensitive to perturbations in overall survival; (iii) species with population growth rates most sensitive to perturbations in juvenile survival; and (iv) species with population growth rates sensitive to perturbations in juvenile survival and fecundity. The results of the present study also showed that (a) elasticity patterns cannot be inferred in a straightforward manner from trade-offs between life-history traits, (b) the sensitivity of a population's growth rate to changes in adult survival and fecundity can be predicted empirically from life span and age at maturity, respectively, (c) elasticities are highly conserved among genera within the same taxonomic family, and (d) there are key divergences between elasticity patterns of freshwater fish and other vertebrate taxa.

scholarly journals Poor horse traders: large mammals trade survival for reproduction during the process of feralization

2009 ◽  
Vol 276 (1663) ◽  
pp. 1911-1919 ◽  
Author(s):  
Sophie Grange ◽  
Patrick Duncan ◽  
Jean-Michel Gaillard
Keyword(s):  
Population Growth ◽  
Reproductive Performance ◽  
High Density ◽  
Adult Survival ◽  
Demographic Parameters ◽  
Adult Males ◽  
High Fecundity ◽  
Population Growth Rates ◽  
Feral Animals ◽  
Feral Ungulates

We investigated density dependence on the demographic parameters of a population of Camargue horses ( Equus caballus ), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adult male survival was not affected, but the survival of foals and adult females decreased with increasing density. Prime-aged females maintained high reproductive performance at high density, and their survival decreased. The higher survival of adult males compared with females at high density presumably results from higher investment in reproduction by mares. The high fecundity in prime-aged females, even when at high density, may result from artificial selection for high reproductive performance, which is known to have occurred in all the major domestic ungulates. Other studies suggest that feral ungulates including cattle and sheep, as these horses, respond differently from wild ungulates to increases in density, by trading adult survival for reproduction. As a consequence, populations of feral animals should oscillate more strongly than their wild counterparts, since they should be both more invasive (as they breed faster), and more sensitive to harsh environmental conditions (as the population growth rate of long-lived species is consistently more sensitive to a given proportional change in adult survival than to the same change in any other vital rate). If this principle proves to be general, it has important implications for management of populations of feral ungulates.

scholarly journals Modelling the ecological niche from functional traits

2010 ◽  
Vol 365 (1557) ◽  
pp. 3469-3483 ◽  
Author(s):  
Michael Kearney ◽  
Stephen J. Simpson ◽  
David Raubenheimer ◽  
Brian Helmuth
Keyword(s):  
Functional Traits ◽  
Evolutionary Biology ◽  
Functional Trait ◽  
Habitat Characteristics ◽  
Great Promise ◽  
Vital Rates ◽  
Theoretical Frameworks ◽  
Geometric Framework ◽  
Population Growth Rates ◽  
The Individual

The niche concept is central to ecology but is often depicted descriptively through observing associations between organisms and habitats. Here, we argue for the importance of mechanistically modelling niches based on functional traits of organisms and explore the possibilities for achieving this through the integration of three theoretical frameworks: biophysical ecology (BE), the geometric framework for nutrition (GF) and dynamic energy budget (DEB) models. These three frameworks are fundamentally based on the conservation laws of thermodynamics, describing energy and mass balance at the level of the individual and capturing the prodigious predictive power of the concepts of ‘homeostasis’ and ‘evolutionary fitness’. BE and the GF provide mechanistic multi-dimensional depictions of climatic and nutritional niches, respectively, providing a foundation for linking organismal traits (morphology, physiology, behaviour) with habitat characteristics. In turn, they provide driving inputs and cost functions for mass/energy allocation within the individual as determined by DEB models. We show how integration of the three frameworks permits calculation of activity constraints, vital rates (survival, development, growth, reproduction) and ultimately population growth rates and species distributions. When integrated with contemporary niche theory, functional trait niche models hold great promise for tackling major questions in ecology and evolutionary biology.

Sign in / Sign up

Export Citation Format

Share Document