This volume summarizes the major findings of the Princeton European Fertility Project. The Project, begun in 1963, was a response to the realization that one of the great social revolutions of the ...last century, the remarkable decline in marital fertility in Europe, was still poorly understood.
Originally published in .
ThePrinceton Legacy Libraryuses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.
Wildlife populations are becoming increasingly fragmented by anthropogenic development. Small and isolated populations often face an elevated risk of extinction, in part due to inbreeding depression. ...Here, we examine the genomic consequences of urbanization in a caracal (Caracal caracal) population that has become isolated in the Cape Peninsula region of the City of Cape Town, South Africa, and is thought to number ~50 individuals. We document low levels of migration into the population over the past ~75 years, with an estimated rate of 1.3 effective migrants per generation. As a consequence of this isolation and small population size, levels of inbreeding are elevated in the contemporary Cape Peninsula population (mean FROH = 0.20). Inbreeding primarily manifests as long runs of homozygosity >10 Mb, consistent with the effects of isolation due to the rapid recent growth of Cape Town. To explore how reduced migration and elevated inbreeding may impact future population dynamics, we parameterized an eco‐evolutionary simulation model. We find that if migration rates do not change in the future, the population is expected to decline, though with a low projected risk of extinction. However, if migration rates decline or anthropogenic mortality rates increase, the potential risk of extinction is greatly elevated. To avert a population decline, we suggest that translocating migrants into the Cape Peninsula to initiate a genetic rescue may be warranted in the near future. Our analysis highlights the utility of genomic datasets coupled with computational simulation models for investigating the influence of gene flow on population viability.
Detecting population declines is a critical task for conservation biology. Logistical difficulties and the spatiotemporal variability of populations make estimation of population declines difficult. ...For statistical reasons, estimates of population decline may be biased when study sites are chosen based on abundance of the focal species. In this situation, apparent population declines are likely to be detected even if there is no decline. This site‐selection bias is mentioned in the literature but is not well known. We used simulations and real population data to examine the effects of site‐selection biases on inferences about population trends. We used a left‐censoring method to detect population‐size patterns consistent with site‐selection bias. The site‐selection bias is an important consideration for conservation biologists, and we offer suggestions for minimizing or mitigating it in study design and analysis.
Article impact statement: Estimates of population declines are biased if studies begin in large populations, and time‐series data show a signature of such an effect.
Sesgos en la Selección de Sitios y las Declinaciones Poblacionales Aparentes en los Estudios a Largo Plazo
Resumen
La detección de las declinaciones poblacionales es una tarea muy importante para la biología de la conservación. Las dificultades logísticas y la variabilidad espacio‐temporal de las poblaciones complican la estimación de las declinaciones poblacionales. Por razones estadísticas, las estimaciones de las declinaciones poblacionales pueden estar sesgadas cuando se eligen los sitios de estudio con base en la abundancia de la especie focal. En esta situación, las declinaciones poblacionales aparentes probablemente sean detectadas sin que exista dicha declinación. Este sesgo en la selección del sitio está mencionado en la literatura, pero sabe poco sobre él. Usamos simulaciones y datos de poblaciones reales para examinar los efectos que tienen los sesgos en la selección de sitio sobre las inferencias que se tienen sobre las tendencias poblacionales. Usamos un método censurado por la izquierda para detectar los patrones en el tamaño poblacional consistentes con el sesgo en la selección de sitios. Este sesgo es una consideración importante para los biólogos de la conservación y ofrecemos sugerencias para minimizarlo o mitigarlo en el análisis y diseño de los estudios.
摘要
监测种群下降是保护生物学中的一项重要任务。然而, 监测的组织实施难度和种群的时空差异导致种群下降难以估计。由于统计学原因, 基于目标物种的丰度来选择研究位点可能会引起对种群下降的估计发生偏差。在这种情况下, 即使种群没有下降, 也可能探测到明显的下降趋势。这样的位点选择偏差在文献中有所提及但尚不清楚。因此, 我们用模拟的和真实的种群数据估计了位点选择偏差对种群趋势推断的影响, 并用左截尾方法分析了与位点选择偏差相一致的种群大小格局。结果显示, 位点选择偏差是保护生物学家需要重点考虑的问题; 本研究为在实验设计和分析中最大程度减少和控制这一影响提供了建议和思考。【翻译: 胡怡思; 审校: 聂永刚】
Background selection is a process whereby recurrent deleterious mutations cause a decrease in the effective population size and genetic diversity at linked loci. Several authors have suggested that ...variation in the intensity of background selection could cause variation in FST across the genome, which could confound signals of local adaptation in genome scans. We performed realistic simulations of DNA sequences, using recombination maps from humans and sticklebacks, to investigate how variation in the intensity of background selection affects FST and other statistics of population differentiation in sexual, outcrossing species. We show that, in populations connected by gene flow, Weir and Cockerham's (1984; Evolution, 38, 1358) estimator of FST is largely insensitive to locus‐to‐locus variation in the intensity of background selection. Unlike FST, however, dXY is negatively correlated with background selection. Moreover, background selection does not greatly affect the false‐positive rate in FST outlier studies in populations connected by gene flow. Overall, our study indicates that background selection will not greatly interfere with finding the variants responsible for local adaptation.
The New Worlds of Thomas Robert Malthusis a sweeping global and intellectual history that radically recasts our understanding of Malthus'sEssay on the Principle of Population, the most famous book on ...population ever written or ever likely to be. Malthus'sEssayis also persistently misunderstood. First published anonymously in 1798, theEssaysystematically argues that population growth tends to outpace its means of subsistence unless kept in check by factors such as disease, famine, or war, or else by lowering the birth rate through such means as sexual abstinence.
Challenging the widely held notion that Malthus'sEssaywas a product of the British and European context in which it was written, Alison Bashford and Joyce Chaplin demonstrate that it was the new world, as well as the old, that fundamentally shaped Malthus's ideas. They explore what the Atlantic and Pacific new worlds-from the Americas and the Caribbean to New Zealand and Tahiti-meant to Malthus, and how he treated them in hisEssay. Bashford and Chaplin reveal how Malthus, long vilified as the scourge of the English poor, drew from his principle of population to conclude that the extermination of native populations by European settlers was unjust.
Elegantly written and forcefully argued,The New Worlds of Thomas Robert Malthusrelocates Malthus'sEssayfrom the British economic and social context that has dominated its reputation to the colonial and global history that inspired its genesis.
Relevance of breeding season fecundity as a driver of population dynamics has been highlighted by many studies. Despite that, knowledge about how brood type specific (i.e. first, second or ...replacement) fecundity affects demography of multiple‐brooded species is limited. In fact, estimation of brood type specific fecundity is often challenging due to imperfect detection of nesting attempts.
We examined the demographic contribution and the feedback on population density of different components of fecundity, along with other vital rates, in a facultative multiple‐brooded migratory bird.
We used a novel formulation of a fecundity model that allows incorporating reproductive data for which information on the type of brood was unknown in some cases, and embedded it into an integrated population model (IPM) to obtain consensual estimates of all demographic rates, including brood type specific fecundities, reproductive success probabilities and proportion of breeding pairs that performed a second or replacement brood. We then conducted transient life table response experiments on IPM estimates to account for non‐stationary environments. We applied the model to two 20‐year datasets collected in a Swiss and a German local population of wrynecks Jynx torquilla.
Brood type specific fecundities and temporal patterns of brood type specific probabilities of success, number of successful and unsuccessful first broods, probability of starting a second or a replacement brood and proportion of pairs that performed a second or a replacement brood differed between the two populations. However, changes in immigration rate and apparent survival were the dominant contributors to temporal variation and large sequential changes in realized population growth rates in both populations. In the Swiss population we also found that second brood fecundity declined when population size increased.
Our study provides insight into the reproductive processes that affect population dynamics and mediate density‐dependent fecundity in a migratory bird. In addition, the analytical approach proposed can be used in other studies of multiple‐brooded species to maximize the use of available fecundity data through the estimation of unknown brood types, thus favouring a better understanding of the demographic contribution of brood type specific fecundity.
A novel analytical approach for the study of fecundity components of multiple‐brooded species and maximize the use of available fecundity data through the estimation of unknown brood types, favouring a better understanding of the demographic contribution of brood type specific fecundity while accounting for non‐stationary environments.
Africa is inferred to be the continent of origin for all modern human populations, but the details of human prehistory and evolution in Africa remain largely obscure owing to the complex histories of ...hundreds of distinct populations. We present data for more than 580,000 SNPs for several hunter-gatherer populations: the Hadza and Sandawe of Tanzania, and the not equalKhomani Bushmen of South Africa, including speakers of the nearly extinct N
Understanding the mechanisms underlying population decline is a critical challenge for conservation biologists. Both deterministic (e.g. habitat loss, fragmentation, and Allee effect) and stochastic ...(i.e. demographic and environmental stochasticity) demographic processes are involved in population decline. Simultaneously, a decrease of population size has far-reaching consequences for genetics of populations by increasing the risk of inbreeding and the strength of genetic drift, which together inevitably results in a loss of genetic diversity and a reduced effective population size (
N
e
). These genetic factors may retroactively affect vital rates (a phenomenon coined ‘inbreeding depression’), reduce population growth, and accelerate demographic decline. To date, most studies that have examined the demographic and genetic processes driving the decline of wild populations have neglected their spatial structure. In this study, we examined demographic and genetic factors involved in the decline of a spatially structured population of a lekking bird, the western capercaillie (
Tetrao urogallus
). To address this issue, we collected capture-recapture and genetic data over a 6-years period in the Vosges Mountains (France). Our study showed that the population of
T. urogallus
experienced a severe decline between 2010 and 2015. We did not detect any Allee effect on survival and recruitment. By contrast, individuals of both sexes dispersed to avoid small subpopulations, thus suggesting a potential behavioral response to a mate finding Allee effect. In parallel to this demographic decline, the population showed low levels of genetic diversity, high inbreeding and low effective population sizes at both subpopulation and population levels. Despite this, we did not detect evidence of inbreeding depression: neither adult survival nor recruitment were affected by individual inbreeding level. Our study underlines the benefit from combining demographic and genetic approaches to investigate processes that are involved in population decline.
Dynamic population mapping using mobile phone data Deville, Pierre; Linard, Catherine; Martin, Samuel ...
Proceedings of the National Academy of Sciences - PNAS,
11/2014, Letnik:
111, Številka:
45
Journal Article
Recenzirano
Odprti dostop
During the past few decades, technologies such as remote sensing, geographical information systems, and global positioning systems have transformed the way the distribution of human population is ...studied and modeled in space and time. However, the mapping of populations remains constrained by the logistics of censuses and surveys. Consequently, spatially detailed changes across scales of days, weeks, or months, or even year to year, are difficult to assess and limit the application of human population maps in situations in which timely information is required, such as disasters, conflicts, or epidemics. Mobile phones (MPs) now have an extremely high penetration rate across the globe, and analyzing the spatiotemporal distribution of MP calls geolocated to the tower level may overcome many limitations of census-based approaches, provided that the use of MP data is properly assessed and calibrated. Using datasets of more than 1 billion MP call records from Portugal and France, we show how spatially and temporarily explicit estimations of population densities can be produced at national scales, and how these estimates compare with outputs produced using alternative human population mapping methods. We also demonstrate how maps of human population changes can be produced over multiple timescales while preserving the anonymity of MP users. With similar data being collected every day by MP network providers across the world, the prospect of being able to map contemporary and changing human population distributions over relatively short intervals exists, paving the way for new applications and a near real-time understanding of patterns and processes in human geography.
Populations of many bumblebee species are declining, with distributions shifting northwards to track suitable climates. Climate change is considered a major contributing factor. Arctic species are ...particularly vulnerable as they cannot shift further north, making assessment of their population viability important. Analysis of levels of whole‐genome variation is a powerful way to analyse population declines and fragmentation. Here, we use genome sequencing to analyse genetic variation in seven species of bumblebee from the Scandinavian mountains, including two classified as vulnerable. We sequenced 333 samples from across the ranges of these species in Sweden. Estimates of effective population size (NE) vary from ~55,000 for species with restricted high alpine distributions to 220,000 for more widespread species. Population fragmentation is generally very low or undetectable over large distances in the mountains, suggesting an absence of barriers to gene flow. The relatively high NE and low population structure indicate that none of the species are at immediate risk of negative genetic effects caused by high levels of genetic drift. However, reconstruction of historical fluctuations in NE indicates that the arctic specialist species Bombus hyperboreus has experienced population declines since the last ice age and we detected one highly inbred diploid male of this species close to the southern limit of its range, potentially indicating elevated genetic load. Although the levels of genetic variation in montane bumblebee populations are currently relatively high, their ranges are predicted to shrink drastically due to the effects of climate change and monitoring is essential to detect future population declines.
PDF
