This article presents a narrative of the unfolding of the Second Demographic Transition (SDT) since the theory was first formulated in 1986. The first part recapitulates the foundations of the ...theory, and documents the spread of the SDT to the point that it now covers most European populations. Also for Europe, it focuses on the relationship between the SDT and the growing heterogeneity in period fertility levels. It is shown that the current positive relationship between SDT and TFR levels is not a violation of the SDT theory, but the outcome of a "split correlation" with different sub-narratives concerning the onset of fertility postponement and the degree of subsequent recuperation in two parts of Europe. The second part of the article addresses the issue of whether the SDT has spread or is currently spreading in industrialized Asian countries. Evidence gathered for Japan, South Korea, Hong Kong, Singapore, and Taiwan is presented. That evidence pertains to both the macro-level (national trends in postponement of marriage and parenthood, rise of cohabitation) and the micro-level (connections between individual values orientations and postponement of parenthood). Strong similarities are found with SDT patterns in Southern Europe, except for the fact that parenthood is still very rare among Asian cohabiting partners.
Current demographic trends raise new questions, challenges and controversies. Comparing demographic trends in Europe and the NAME-region (North Africa and the Middle East), this book demonstrates how ...population change interacts with changing economic landscapes, social distinctions and political realities. A variety of drivers contribute to demographic change in the various regions and countries considered, such as family policies, economic realities, the impact of educational differentials and the attitudes towards marriage. On the macro-level the new trends are restructuring the age composition of populations and are reshaping the life courses of individuals and families. In turn, the impact demographic forces have on the organisation of labour markets, on fiscal policies, on the care of the elderly, on migration flows and on political changes can be quite radical.
About 50 y ago, Crow and Kimura
(1970) and Ohta and Kimura
22, 201-204 (1973) laid the foundations of conservation genetics by predicting the relationship between population size and genetic marker ...diversity. This work sparked an enormous research effort investigating the importance of population dynamics, in particular small population size, for population mean performance, population viability, and evolutionary potential. In light of a recent perspective J. C. Teixeira, C. D. Huber,
118, 10 (2021) that challenges some fundamental assumptions in conservation genetics, it is timely to summarize what the field has achieved, what robust patterns have emerged, and worthwhile future research directions. We consider theory and methodological breakthroughs that have helped management, and we outline some fundamental and applied challenges for conservation genetics.
Integrated population models Plard, Floriane; Fay, Rémi; Kéry, Marc ...
Ecology (Durham),
June 2019, Letnik:
100, Številka:
6
Journal Article
Recenzirano
Population dynamics models have long assumed that populations are composed of a restricted number of groups, where individuals in each group have identical demographic rates and where all groups are ...similarly affected by density-dependent and -independent effects. However, individuals usually vary tremendously in performance and in their sensitivity to environmental conditions or resource limitation, such that individual contributions to population growth will be highly variable. Recent efforts to integrate individual processes in population models open up new opportunities for the study of eco-evolutionary processes, such as the density-dependent influence of environmental conditions on the evolution of morphological, behavioral, and life-history traits. We review recent advances that demonstrate how including individual mechanisms in models of population dynamics contributes to a better understanding of the drivers of population dynamics within the framework of integrated population models (IPMs). IPMs allow for the integration in a single inferential framework of different data types as well as variable population structure including sex, social group, or territory, all of which can be formulated to include individual-level processes. Through a series of examples, we first show how IPMs can be beneficial for getting more accurate estimates of demographic traits than classic matrix population models by including basic population structure and their influence on population dynamics. Second, the integration of individual- and population-level data allows estimating density-dependent effects along with their inherent uncertainty by directly using the population structure and size to feedback on demography. Third, we show how IPMs can be used to study the influence of the dynamics of continuous individual traits and individual quality on population dynamics. We conclude by discussing the benefits and limitations of IPMs for integrating data at different spatial, temporal, and organismal levels to build more mechanistic models of population dynamics.
Many migratory species are in decline across their geographical ranges. Single‐population studies can provide important insights into drivers at a local scale, but effective conservation requires ...multi‐population perspectives. This is challenging because relevant data are often hard to consolidate, and state‐of‐the‐art analytical tools are typically tailored to specific datasets.
We capitalized on a recent data harmonization initiative (SPI‐Birds) and linked it to a generalized modelling framework to identify the demographic and environmental drivers of large‐scale population decline in migratory pied flycatchers (Ficedula hypoleuca) breeding across Britain.
We implemented a generalized integrated population model (IPM) to estimate age‐specific vital rates, including their dependency on environmental conditions, and total and breeding population size of pied flycatchers using long‐term (34–64 years) monitoring data from seven locations representative of the British breeding range. We then quantified the relative contributions of different vital rates and population structure to changes in short‐ and long‐term population growth rate using transient life table response experiments (LTREs).
Substantial covariation in population sizes across breeding locations suggested that change was the result of large‐scale drivers. This was supported by LTRE analyses, which attributed past changes in short‐term population growth rates and long‐term population trends primarily to variation in annual survival and dispersal dynamics, which largely act during migration and/or nonbreeding season. Contributions of variation in local reproductive parameters were small in comparison, despite sensitivity to local temperature and rainfall within the breeding period.
We show that both short‐ and long‐term population changes of British breeding pied flycatchers are likely linked to factors acting during migration and in nonbreeding areas, where future research should be prioritized. We illustrate the potential of multi‐population analyses for informing management at (inter)national scales and highlight the importance of data standardization, generalized and accessible analytical tools, and reproducible workflows to achieve them.
Tackling large‐scale population declines requires multi‐population studies. Capitalizing on the SPI‐birds data standardization initiative, this study reveals that population changes of migratory flycatchers across its UK breeding distribution are driven by survival and dispersal. It also provides an integrated modelling workflow for analyses at even larger scales.
The distribution of city populations has attracted much attention, in part because it constrains models of local growth. However, there is no consensus on the distribution below the very upper tail, ...because available data need to rely on "legal" rather than "economic" definitions for medium and small cities. To remedy this difficulty, we construct cities "from the bottom up" by clustering populated areas obtained from high-resolution data. We find that Zipf 's law for population holds for cities as small as 5,000 inhabitants in Great Britain and 12,000 inhabitants in the US. We also find a Zipf 's law for areas. JEL: R11, R12, R23 PUBLICATION ABSTRACT
On 28 April 2011, China's state statistics bureau released its first report on the country's 2010 population census. The report states that the total population of mainland China reached 1.3397 ...billion in 2010, with an annual average population growth rate of 0.57% during the previous 10 years. The share of the total population aged 0 to 14 declined from 22.9% in 2000 to 16.6% in 2010, whereas the proportion aged 65 and above grew from 7.0% to 8.9% during the same period. This indicates that China's population is aging rapidly. The report also shows that China is urbanizing, with nearly half of the population—665.57 million people, or 49.7%—living in urban areas, an increase of 13 percentage points over the 2000 figure. Moreover, about 260 million Chinese people are living away from where they are formally registered, and the overwhelming majority of them (about 220 million) are rural migrants living and working in urban areas but without formal urban household registration status. China is at a demographic turning point: It is changing from an agricultural society into an urban one, from a young society to an old one, and from a society attached to the land to one that is very much on the move.
Background: Emergency general surgery (EGS) conditions cause a disproportionately high degree of morbidity and mortality among surgical patients. The objective of our study was to generate estimates ...of the potential access to EGS care within various driving distances for Ontario residents in each geographic region. Methods: Institutional details were collected using a survey of all hospitals offering urgent and emergent general surgical care in Ontario (n = 114). The locations of these hospitals were mapped using geographic information systems (GIS), and land catchment areas were modelled for 30-, 45-, 60- and 90-minute travel times using the 2019 Ontario road network. Population data were reported on the basis of the 2016 census blocks, which are the smallest geographic units by which to report population. Travel distances were determined between the geographic centroid of the census block and the closest hospital. Results were stratified for certain characteristics offered by the institution, such as EGS care available (n = 114), dedicated EGS service model (n = 36), 24/7 emergency department (ED) (n = 97) and 24/7 operating room (OR) capabilities (n = 76). Results: Nearly all (96%, n = 12 933 892) of the Ontario population lives within 30 minutes' driving time to a hospital that provides care to EGS patients, and 93% (n = 12 471 908) can access a hospital with 24/7 OR capabilities in this same time frame. Around-the-clock ED availability within 30 minutes is potentially accessible for 93% (n = 12 471 908) of the population. However, only 76% (n = 10 220 018) live within 30 minutes of a facility with an EGS model of care. Substantial regional disparities are present and appear to particularly affect remote communities. Conclusion: Most Ontario residents live within a 30-minute driving distance of a hospital able to provide emergent or urgent general surgical care, with slightly fewer able to access 24/7 operative facilities. Despite this, striking differences persist in access for remote and rural areas of the province.
Effective population size is a fundamental parameter in population genetics, evolutionary biology, and conservation biology, yet its estimation can be fraught with difficulties. Several methods to ...estimate Ne from genetic data have been developed that take advantage of various approaches for inferring Ne. The ability of these methods to accurately estimate Ne, however, has not been comprehensively examined. In this study, we employ seven of the most cited methods for estimating Ne from genetic data (Colony2, CoNe, Estim, MLNe, ONeSAMP, TMVP, and NeEstimator including LDNe) across simulated datasets with populations experiencing migration or no migration. The simulated population demographies are an isolated population with no immigration, an island model metapopulation with a sink population receiving immigrants, and an isolation by distance stepping stone model of populations. We find considerable variance in performance of these methods, both within and across demographic scenarios, with some methods performing very poorly. The most accurate estimates of Ne can be obtained by using LDNe, MLNe, or TMVP; however each of these approaches is outperformed by another in differing demographic scenario. Knowledge of the approximate demography of population as well as the availability of temporal data largely improves Ne estimates.
The household registration (hukou) system in China, classifying each person as a rural or an urban resident, is a major means of controlling populatin mobility and determining eligibility for ...state-provided services and welfare. Established in the late 1950s, it was initially used to bar rural-to-urban migration. After the late 1970s reforms, an inflow of rural migrant workers was allowed into the cities to meet labor demands in the burgeoning export industries and urban services without, however, changing the migrants' registered status, thus precluding their access to subsidized housing and other benefits available to those with urban registration. While there have been many calls for reforming this system, progress has been limited. Proposed reforms have attracted increasing academic and media attention.
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