AbstractIn many species, individuals are embedded in a network of kin with whom they interact. Interactions between kin can affect survival and fertility rates and thus the life history of individuals. These interactions indirectly affect both the network of kin and the dynamics of the population.
View Article and Find Full Text PDFJ Gerontol A Biol Sci Med Sci
November 2024
Background: Although the family plays a pivotal role in older adults' care, there is limited research on how evolving demographic trends affect older adults' support networks and how the trends vary by race. To fill this gap, we examine the influence of shifting family demographics on future care needs for older adults with dementia, emphasizing the unequal health and potential caregiving burdens by race in the United States.
Methods: Using demographic models of kinship, we estimate the availability of potential caregivers, and dementia prevalence among one's kin by race, kin type, and the age of a focal person from 2000 to 2060.
Demographers have long attempted to project future changes in the size and composition of populations, but have ignored what these processes will mean for the size, composition, and age distribution of family networks. Kinship structures matter because family solidarity-a crucial source of informal care for millions of people around the world-is conditional on kin being alive. Here, we present innovative projections of biological kin for the 1950 to 2100 period and discuss what they imply for the availability of informal care.
View Article and Find Full Text PDFMany animals form long-term monogamous pair bonds, and the disruption of a pair bond (through either divorce or widowhood) can have significant consequences for individual vital rates (survival, breeding, and breeding success probabilities) and life-history outcomes (lifetime reproductive success [LRS], life expectancy). Here, we investigated the causes and consequences of pair-bond disruption in wandering albatross (). State-of-the-art statistical and mathematical approaches were developed to estimate divorce and widowhood rates and their impacts on vital rates and life-history outcomes.
View Article and Find Full Text PDFThe life histories of organisms are expressed as rates of development, reproduction, and survival. However, individuals may experience differential outcomes for the same set of rates. Such individual stochasticity generates variance around familiar mean measures of life history traits, such as life expectancy and the reproductive number R0.
View Article and Find Full Text PDFThe Covid-19 pandemic has not affected the population evenly. This must be acknowledged when it comes to understanding the Covid-19 death toll and answering the question of how many life years have been lost. We use level of geriatric care to account for variation in remaining life expectancy among individuals that died during 2020.
View Article and Find Full Text PDFIndividuals differ in many ways. Most produce few offspring; a handful produce many. Some die early; others live to old age.
View Article and Find Full Text PDFMost studies on unemployment have assessed its individual-level costs. However, beyond its effects on individuals, unemployment incurs costs for their immediate families and extended kin. Close kin provide the majority of social support for unemployed adults.
View Article and Find Full Text PDFAbstractVariance among individuals in fitness components reflects both genuine heterogeneity between individuals and stochasticity in events experienced along the life cycle. Maternal age represents a form of heterogeneity that affects both the mean and the variance of lifetime reproductive output (LRO). Here, we quantify the relative contribution of maternal age heterogeneity to the variance in LRO using individual-level laboratory data on the rotifer to parameterize a multistate age × maternal age matrix model.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
July 2020
Maternal effect senescence-a decline in offspring survival or fertility with maternal age-has been demonstrated in many taxa, including humans. Despite decades of phenotypic studies, questions remain about how maternal effect senescence impacts evolutionary fitness. To understand the influence of maternal effect senescence on population dynamics, fitness, and selection, we developed matrix population models in which individuals are jointly classified by age and maternal age.
View Article and Find Full Text PDFVariance in life history outcomes among individuals is a requirement for natural selection, and a determinant of the ecological dynamics of populations. Heterogeneity among individuals will cause such variance, but so will the inherently stochastic nature of their demography. The relative contributions of these variance components - stochasticity and heterogeneity - to life history outcomes are presented here in a general, demographic calculation.
View Article and Find Full Text PDFBackground/introduction: Despite a growing population of chronically and acute critically ill neonatal and pediatric patients, there were few published articles related to moral distress as experienced by nurses caring for these patients.
Objectives/aims: The aim of this study was to define moral distress based on the perceptions and experiences of neonatal and pediatric critical care nurses.
Methods: A qualitative descriptive study using focus group methodology was undertaken.
The Paris Agreement is a multinational initiative to combat climate change by keeping a global temperature increase in this century to 2°C above preindustrial levels while pursuing efforts to limit the increase to 1.5°C. Until recently, ensembles of coupled climate simulations producing temporal dynamics of climate en route to stable global mean temperature at 1.
View Article and Find Full Text PDFTheor Popul Biol
December 2019
The outcome of natural selection depends on the demographic processes of birth, death, and development. Here, we derive conditions for protected polymorphism in a population characterized by age- or stage-dependent demography with two sexes. We do so using a novel two-sex matrix population model including basic Mendelian genetics (one locus, two alleles, random mating).
View Article and Find Full Text PDFObjectives: Two processes generate total variance in age at death: heterogeneity (between-group variance) and individual stochasticity (within-group variance). Limited research has evaluated how these two components have changed over time. We quantify the degree to which area-level deprivation contributed to total variance in age at death in Scotland between 1981 and 2011.
View Article and Find Full Text PDFDemographic processes and ecological interactions are central to understanding evolution and vice versa. We present a novel framework that combines basic Mendelian genetics with the powerful demographic approach of matrix population models. The ecological components of the model may be stage classified or age classified, linear or nonlinear, time invariant or time varying, and deterministic or stochastic.
View Article and Find Full Text PDFClimate change is affecting species' distributions and abundances worldwide. Baseline population estimates, against which future observations may be compared, are necessary if we are to detect ecological change. Arctic sea ice ecosystems are changing rapidly and we lack baseline population estimates for many ice-associated species.
View Article and Find Full Text PDFBackground: Research suggests that people with epilepsy (PWE) are more likely to experience depression and anxiety than the general population. Given the adversity associated with the condition, resilience may also be important. However, to date, resilience has been largely overlooked in the epilepsy literature.
View Article and Find Full Text PDFThis paper presents a comprehensive theory for the demographic analysis of populations in which individuals are classified by both age and stage. The earliest demographic models were age classified. Ecologists adopted methods developed by human demographers and used life tables to quantify survivorship and fertility of cohorts and the growth rates and structures of populations.
View Article and Find Full Text PDFRecent studies unravelled the effect of climate changes on populations through their impact on functional traits and demographic rates in terrestrial and freshwater ecosystems, but such understanding in marine ecosystems remains incomplete. Here, we evaluate the impact of the combined effects of climate and functional traits on population dynamics of a long-lived migratory seabird breeding in the southern ocean: the black-browed albatross (Thalassarche melanophris, BBA). We address the following prospective question: "Of all the changes in the climate and functional traits, which would produce the biggest impact on the BBA population growth rate?" We develop a structured matrix population model that includes the effect of climate and functional traits on the complete BBA life cycle.
View Article and Find Full Text PDFBackground: Increases in human longevity have made it critical to distinguish healthy longevity from longevity without regard to health. Current methods focus on expectations of healthy longevity, and are often limited to binary health outcomes (e.g.
View Article and Find Full Text PDFOne critical feature of any well-engineered system is its resilience to perturbation and minor damage. The purpose of the current study was to investigate how resilience is achieved in higher cognitive systems, which we explored through the domain of semantic cognition. Convergent evidence implicates the bilateral anterior temporal lobes (ATLs) as a conceptual knowledge hub.
View Article and Find Full Text PDFObjectives: The aim of this review was to identify quantitative correlates, predictors, and outcomes of stigma in adults with epilepsy living in Western countries.
Methods: To identify relevant literature, four academic databases (PsycINFO, CINAHL, PubMed, and Scopus) were systematically searched using key terms related to stigma and epilepsy.
Results: Thirty-three research papers reporting findings from 25 quantitative studies of correlates of stigma in epilepsy were identified.