Differential Stage-Specific Mortality as a Mechanism for Diversification.

AbstractIndividual variability in mortality is widespread in nature. The general rule is that larger organisms have a greater chance of survival than smaller conspecifics. There is growing evidence that differential mortality between developmental stages has important consequences for the ecology and evolution of populations and communities. However, we know little about how it can influence diversification. Using an eco-evolutionary model of diversification that considers individual variability in mortality, I show that commonly observed differences in mortality between juveniles and adults can facilitate adaptive diversification. In particular, diversification is expected to be less restricted when mortality is more biased toward juveniles. Additionally, I find stage-specific differences in metabolic cost and foraging capacity to further facilitate diversification when adults are slightly superior competitors, due to either a lower metabolic cost or a higher foraging capacity, than juveniles. This is because by altering the population composition, differential stage-specific mortality and competitive ability can modulate the strength of intraspecific competition, which in turn determines the outcome of diversification. These results demonstrate the strong influence that ecological differences between developmental stages have on diversification and highlight the need for integrating developmental processes into diversification theory.

Female-biased birth sex ratio in a female dispersal primate suggests local resource competition.

Group living may entail local resource competition (LRC) which can be reduced if the birth sex ratio (BSR) is biased towards members of the dispersing sex who leave the group and no longer compete locally with kin. In primates, the predicted relationship between dispersal and BSR is generally supported although data for female dispersal species are rare and primarily available from captivity. Here, we present BSR data for Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) at the Phu Khieo Wildlife Sanctuary, Thailand (N = 104). In this population, nearly all natal females dispersed, while natal males stayed or formed new groups nearby. The slower reproductive rate in larger groups suggests that food can be a limiting resource. In accordance with LRC, significantly more females than males were born (BSR 0.404 males/all births) thus reducing future competition with kin. This bias was similar in 2-year-olds (no sex-differential mortality). It became stronger in adults, supporting our impression of particularly fierce competition among males. To better evaluate the importance of BSR, more studies should report sex ratios throughout the life span, and more data for female dispersal primates need to be collected, ideally for multiple groups of different sizes and for several years.

[Family reconstitution and online genealogies to analyze the sex-specific differential mortality in the historical context]. / Familienrekonstitution und Online-Genealogien zur Analyse der geschlechtsspezifischen differenziellen Sterblichkeit im historischen Kontext.

BACKGROUND: Family reconstitution and data from online genealogies, such as FamiLinx, are two potential sources for investigating mortality dynamics for the period before official lifetables became available. In this paper, we use two of them, the family reconstitution of Imhof and the FamiLinx dataset based on geni.com, to estimate dynamics in life expectancy and discuss the sex-specific differential mortality in the German Empire. METHOD: Sex-specific lifetables are estimated for the territory of the German Empire from the individual data of the family reconstitution and the online genealogies. On the basis of these lifetables, we estimate the conditional life expectancy and derive the corresponding sex-specific differential mortality. Findings are compared with the official lifetable of the German Empire in 1871-1910. The contribution of each age group to the differential mortality is determined using the stepwise-replacement algorithm. RESULTS: The family reconstitution overestimates conditional life expectancy less than FamiLinx after 1871, when official lifetables are available in the German Empire. However, both sources fail to capture the sex-specific mortality differentials of the official lifetables at the end of the nineteenth century and show a higher life expectancy for males instead of females. The bias in sex-specific mortality rates is particularly pronounced in the age groups 15 to 45. DISCUSSION: Finally, we discuss possible explanations for the biased findings. Notability bias, the patriarchal approach to family trees, and maternal mortality are important mechanisms in the FamiLinx dataset. Censoring due to mobility serves as a potential reason for the bias in the family reconstitution.

Leaders and Laggards in Life Expectancy Among European Scholars From the Sixteenth to the Early Twentieth Century.

When did mortality first start to decline, and among whom? We build a large, new data set with more than 30,000 scholars covering the sixteenth to the early twentieth century to analyze the timing of the mortality decline and the heterogeneity in life expectancy gains among scholars in the Holy Roman Empire. The large sample size, well-defined entry into the risk group, and heterogeneity in social status are among the key advantages of the new database. After recovering from a severe mortality crisis in the seventeenth century, life expectancy among scholars started to increase as early as in the eighteenth century, well before the Industrial Revolution. Our finding that members of scientific academies-an elite group among scholars-were the first to experience mortality improvements suggests that 300 years ago, individuals with higher social status already enjoyed lower mortality. We also show, however, that the onset of mortality improvements among scholars in medicine was delayed, possibly because these scholars were exposed to pathogens and did not have germ theory knowledge that might have protected them. The disadvantage among medical professionals decreased toward the end of the nineteenth century. Our results provide a new perspective on the historical timing of mortality improvements, and the database accompanying our study facilitates replication and extensions.

The Age Profile of Life Satisfaction After Age 65 in the U.S.

Although income and wealth are frequently used as indicators of well-being, they are increasingly augmented with subjective measures such as life satisfaction to capture broader dimensions of the well-being of individuals. Based on large surveys of individuals, life satisfaction in cross-section often is found to increase with age beyond retirement into advanced old age. It may seem puzzling that average life satisfaction does not decline at older ages because older individuals are more likely to experience chronic or acute health conditions, or the loss of a spouse. Accordingly, this empirical pattern has been called the "paradox of well-being." We examine the age profile of life satisfaction of the U.S. population age 65 or older in the Health and Retirement Study (HRS), and find that in cross-section it increases between age 65 and 71 and is flat thereafter; but based on the longitudinal dimension of the HRS, life satisfaction significantly declines with age and the rate of decline accelerates with age. We reconcile the cross-section and longitudinal measurements by showing that both differential mortality and differential non-response bias the cross-sectional age profile upward: individuals with higher life satisfaction and in better health tend to live longer, and, among survivors, individuals with higher life satisfaction are more likely to remain in the survey, masking the decline in life satisfaction experienced by individuals as they age. We conclude that the optimistic view about increasing life satisfaction at older ages based on cross-sectional data is not warranted.

The effect of population density on growth and survival of a Neotropical annual killifish.

We used a field experiment to test the effects of population density on the growth rate and survival of Austrolebias bellottii, a Neotropical annual killifish. Effects differed between the sexes: males at high densities achieved a smaller final size and experienced higher mortality while no such effects were observed in females. This sex-specific effect could be an indirect consequence of mate competition.

Quantifying the relationship between age at diagnosis and breast cancer-specific mortality.

PURPOSE: The relationship between age at diagnosis and breast cancer-specific mortality (BCSM) is unclear. The aim of this study was to examine the nature of this relationship using rigorous statistical methodology. METHODS: A historical cohort study of adult women with invasive breast cancer in the SEER database from 2000 to 2015 was conducted. Multivariable Cox's cause-specific hazards model was used to evaluate the association of age at diagnosis with risk of BCSM. Functional relationship of age was assessed using cumulative sums of Martingale residuals and the Kolmogorov-type supremum test. RESULTS: A total of 206,332 women were eligible for study. Mean age at diagnosis was 59.7 ± 13.8 years. Median follow-up was 80 months. During the study period, 21,771 women (10.6%) died from breast cancer and 18,566 (9.0%) died from other causes. Cumulative incidence of BCSM at 120 months post-diagnosis was 14.4% (95% CI 14.2-14.6%). Age was found to be quadratically related to the risk of BCSM (p < 0.001), with a nadir at 45 years of age. The final Cox model suggests that a 30-year-old woman has approximately the same adjusted BCSM risk (HR 1.187, 95% CI 1.187-1.188) as a 60-year-old woman (HR 1.174, 95% CI 1.174-1.175). CONCLUSIONS: Women diagnosed with breast cancer at the extremes of age suffer disproportionate rates of cancer-specific mortality. The relationship between age at diagnosis and adjusted risk of BCSM is complex, consistent with a quadratic function. With the growing appreciation for breast cancer as a heterogeneous disease, it is essential to accurately address age as a prognostic risk factor in predictive models.

The Impact of Forced Migration on Mortality: Evidence From German Pension Insurance Records.

We examine the long-run effects of forced migration for individuals who were displaced from Eastern Europe to Germany in the aftermath of World War II. Evidence suggests that displaced individuals were worse off economically, facing a considerably lower income and a higher unemployment risk than comparable nondisplaced Germans, even 20 years after being expelled. We extend this literature by investigating mortality outcomes. Using social security records that document the exact date of death and a proxy for pre-retirement lifetime earnings, we estimate a significantly and considerably higher mortality risk among forced migrants compared with nondisplaced West Germans. The adverse displacement effect persists throughout the earnings distribution except for the top quintile. Although forced migrants were generally worse off regarding mortality outcomes, those with successful labor market histories seem to have overcome the long-lasting negative consequences of flight and expulsion.

[Death is a respecter of persons : 30 years of research comparing European countries regarding social inequality in mortality]. / Vor dem Tod sind alle ungleich : 30 Jahre Forschung zu Mortalitätsunterschieden nach Sozialstatus im europäischen Ländervergleich.

BACKGROUND: In 1989 the first international comparisons of mortality differences according to educational level and occupational status were published. A few years later systematic comparisons between European countries were initiated at the Erasmus University in Rotterdam. This became a trigger for several European Union (EU)-funded collaboration programs scrutinizing social inequalities in health. The collaboration revealed substantial differences in mortality within and between European populations. OBJECTIVE: This article provides a synthesis of the most important research results over the past 30 years and also identifies existing research gaps and potentials. MATERIAL AND METHODS: Descriptive summary of research results comparing European countries regarding male and female all-cause and cause-specific mortality according to educational level and occupational status. RESULTS: In all European populations analyzed there was a consistent gradient with substantial and in part increasing advantages for higher socioeconomic status groups. There is, however, substantial variation between individual countries. This also applies to trends and cause of death-specific analyses. While relative differences have increased in virtually all populations, absolute differences have often decreased in many populations. Among women and in higher ages the relative differences were smaller. Within Europe, the southern countries had the smallest and the eastern countries the largest gradients. Tobacco and alcohol-related diseases had an especially noteworthy impact on trends and gradients. CONCLUSION: The evidence for social health inequalities and their determinants has substantially improved during the past 30 years; however, there remains substantial potential for future research questions, for example concerning the contribution of the different phases of life to healthy aging.

Risk of Developing Dementia at Older Ages in the United States.

Dementia is increasingly recognized as a major source of disease burden in the United States, yet little research has evaluated the lifecycle implications of dementia. To address this research gap, this article uses the Aging, Demographics, and Memory Study (ADAMS) to provide the first nationally representative, longitudinal estimates of the probability that a dementia-free person will develop dementia later in life. For the 1920 birth cohort, the average dementia-free 70-year-old male had an estimated 26.9 % (SE = 3.2 %) probability of developing dementia, and the average dementia-free 70-year-old female had an estimated 34.7 % (SE = 3.7 %) probability. These estimates of risk of dementia are higher for younger, lower-mortality cohorts and are substantially higher than those found in local epidemiological studies in the United States, suggesting a widespread need to prepare for a life stage with dementia.

Carry-over effects of conditions at the wintering grounds on breeding plumage signals in a migratory bird: roles of phenotypic plasticity and selection.

To understand the consequences of ever-changing environment on the dynamics of phenotypic traits, distinguishing between selection processes and individual plasticity is crucial. We examined individual consistency/plasticity in several male secondary sexual traits expressed during the breeding season (white wing and forehead patch size, UV reflectance of white wing patch and dorsal melanin coloration) in a migratory pied flycatcher (Ficedula hypoleuca) population over an 11-year period. Furthermore, we studied carry-over effects of three environmental variables (NAO, a climatic index; NDVI, a vegetation index; and rainfall) at the wintering grounds (during prebreeding moult) on the expression of these breeding plumage traits of pied flycatcher males at individual and population levels. Whereas NAO correlates negatively with moisture in West Africa, NDVI correlates positively with primary production. Forehead patch size and melanin coloration were highly consistent within individuals among years, whereas the consistency of the other two traits was moderate. Wing patch size decreased with higher NAO and increased with higher rainfall and NDVI at the individual level. Interestingly, small-patched males suffered lower survival during high NAO winters than large-patched males, and vice versa during low NAO winters. These counteracting processes meant that the individual-level change was masked at the population level where no relationship was found. Our results provide a good example of how variation in the phenotypic composition of a natural population can be a result of both environment-dependent individual plasticity and short-term microevolution. Moreover, when plasticity and viability selection operate simultaneously, their impacts on population composition may not be evident.

Incidence estimation using a single cross-sectional age-specific prevalence survey with differential mortality.

Here, we present a method for incidence estimation of a curable, non-recurring disease when data from a single cross-sectional survey are used together with population-level mortality rates and an assumption of differential mortality of diseased versus non-diseased individuals. The motivating example is cataract, and the VISION2020 goal to eliminate avoidable blindness globally by 2020. Reliable estimates of current and future cataract disease burden are required to predict how many surgeries would need to be performed to meet the VISION2020 goals. However, incidence estimates, needed to derive future burden, are not as easily available, due to the cost of conducting cohort studies. Disease is defined at the person-level in accordance with the WHO person-level definition of blindness. An extension of the standard time homogeneous illness-death model to a four-state model is described, which allows the disease to be cured, whereby surgery is performed on at least one diseased eye. Incidence is estimated, and the four-state model is used to predict disease burden assuming different surgical strategies whilst accounting for the competing risk of death. The method is applied to data from approximately 10,000 people from a survey of visual impairment in Nigeria.

An evolutionary explanation of female-biased sexual size dimorphism in North Sea plaice, Pleuronectes platessa L.

Sexual size dimorphism (SSD) is caused by differences in selection pressures and life-history trade-offs faced by males and females. Proximate causes of SSD may involve sex-specific mortality, energy acquisition, and energy expenditure for maintenance, reproductive tissues, and reproductive behavior. Using a quantitative, individual-based, eco-genetic model parameterized for North Sea plaice, we explore the importance of these mechanisms for female-biased SSD, under which males are smaller and reach sexual maturity earlier than females (common among fish, but also arising in arthropods and mammals). We consider two mechanisms potentially serving as ultimate causes: (a) Male investments in male reproductive behavior might evolve to detract energy resources that would otherwise be available for somatic growth, and (b) diminishing returns on male reproductive investments might evolve to reduce energy acquisition. In general, both of these can bring about smaller male body sizes. We report the following findings. First, higher investments in male reproductive behavior alone cannot explain the North Sea plaice SSD. This is because such higher reproductive investments require increased energy acquisition, which would cause a delay in maturation, leading to male-biased SSD contrary to observations. When accounting for the observed differential (lower) male mortality, maturation is postponed even further, leading to even larger males. Second, diminishing returns on male reproductive investments alone can qualitatively account for the North Sea plaice SSD, even though the quantitative match is imperfect. Third, both mechanisms can be reconciled with, and thus provide a mechanistic basis for, the previously advanced Ghiselin-Reiss hypothesis, according to which smaller males will evolve if their reproductive success is dominated by scramble competition for fertilizing females, as males would consequently invest more in reproduction than growth, potentially implying lower survival rates, and thus relaxing male-male competition. Fourth, a good quantitative fit with the North Sea plaice SSD is achieved by combining both mechanisms while accounting for sex-specific costs males incur during their spawning season. Fifth, evolution caused by fishing is likely to have modified the North Sea plaice SSD.

Impact of older age on the long-term survival in living-donor liver transplantation: A propensity score matching analysis.

BACKGROUND: Prevalence of the end-stage liver disease in the elderly patients indicating a liver transplantation (LT) has been increasing. There is no universally accepted upper age limit for LT candidates but the functional status of older patients is important in pre-LT evaluation. This study aimed to examine the impact of older age on survival after living donor liver transplantation (LDLT). METHOD: A total of 171 LDLT recipients were assessed in two groups: age ≥65 and < 65. To eliminate selection bias propensity score matching (PSM) was performed, and 56 of 171 recipients were included in this study. RESULTS: There were 20 recipients in the older group and 36 in the younger. The 1-, 3-, and 5-year survival rates were 65.0%, 60.0%, and 60.0% in group 1; 88.9%, 84.7%, and 71.4% in group 2, respectively. The 1-year survival was significantly lower in the older recipients; however, overall survival rates were similar between the groups. Of the 56 recipients, 15 (27%) deaths were observed in overall, and 11 (20%) in 1-year follow-up. The univariate regression analysis after PSM revealed that MELD score affected 1- year survival and the multivariate analysis revealed that age ≥65 years and MELD score were the predictors of 1-year survival. CONCLUSION: At first sight, before PSM, survival appeared to be worse for older recipients. However, we have shown that there were confounding effects of clinical variables in the preliminary evaluation. After the elimination of this bias with PSM, This study highlights that older recipients have similar outcomes as youngers in LDLT for long-term survival.

The Importance of Education for Middle- and Old-Age Mortality in Chile: Estimates From Panel Data Linked to Death Records.

OBJECTIVES: To examine the association between education and mortality by age and gender in Chile. METHODS: We drew data from 10,147 adults aged 40 years and over from the Chilean Social Protection Survey linked to the national death records. We specify five Cox regression models to estimate the main and interaction effects for education levels, age, sex, and mortality. RESULTS: The hazard ratios reduce with increasing education. Secondary and tertiary education levels are associated, respectively, with 34% and 41% lower hazard rates than 0-4 years of schooling. Also, the educational gradient in mortality is significantly weaker at older ages, and it does not differ by gender. DISCUSSION: Our findings endorse the negative association of formal education with adult mortality, uncovering Chile's structural problems despite the economic improvements underway. It also corroborates the importance of novel longitudinal data for mortality analyses in Latin America.

The Growing Socioeconomic Gap in Lifetime Social Security Retirement Benefits: Current and Future Retirees.

OBJECTIVES: Increasing socioeconomic disparities, including in life expectancy, have important implications for the U.S. Social Security program. This study examined inter- and intracohort trends in Social Security retirement benefits, paying special attention to how lifetime benefit trajectories by socioeconomic circumstance shift across cohorts encompassing current and future retirees. METHODS: Using a dynamic microsimulation model based on representative survey data linked to administrative records, we developed a set of cohort-specific projections that estimate monthly and lifetime Social Security retirement benefits for retirees spanning the early baby boom (1945-1954) to Generation X (1965-1974) cohorts. RESULTS: We found a widening socioeconomic gap in projected monthly and lifetime benefits for men and women, especially on a lifetime basis. This divergence is associated with stagnation of benefit levels among lower socioeconomic status groups coupled with upward shifts among higher strata groups. Distributional changes are linked with increasing differential mortality, but other factors also likely play a role such as rising education premiums, growing earnings inequality, and changes in women's work and relationship histories. DISCUSSION: Widening mortality differentials can lead to distributional changes in the U.S. Social Security program. Microsimulation methodology lends insights into how the socioeconomic gap in monthly and lifetime benefit distributions may change among future older Americans in the context of differential mortality and other demographic changes. Moving forward in time, these complex patterns could offset some of the progressivity built into the system.

Contrasts in alcohol-related mortality in Czechia and Lithuania: Analysis of time trends and educational differences.

INTRODUCTION AND AIMS: Globally, Czechia and Lithuania are among the top-ranking countries in terms of high alcohol consumption. This study highlights notable contrasts in temporal trends in alcohol-related mortality and identifies country-specific patterns in educational differences. DESIGN AND METHODS: The study uses harmonised cause-of-death series from the Human Cause of Death Database. Mortality disparities by education were assessed using census-linked mortality data. Directly standardised death rates were used to estimate levels of national and group-specific mortality. Relative and absolute mortality differences by education were assessed by range-type measures (Poisson regression mortality ratios and rate differences) and Gini-type measures. RESULTS: Between 1994-1995 and 2016, the absolute difference between Czechia and Lithuania in terms of alcohol-related age-standardised death rates (per 1 000 000) decreased from 450 for males and 130 for females to 76 in males and 11 in females. In both countries, alcohol-related mortality was markedly higher among persons of lower education levels. Lithuanian males experienced the highest absolute inequalities measured by rate difference between the low and high educated (740 per million), while Lithuanian females showed the most pronounced relative inequalities (6.70-fold difference between low and high educated). The corresponding figures were less than half for Czechia. DISCUSSION AND CONCLUSIONS: Reducing educational disparities in alcohol-related mortality within both countries would have a substantial impact on overall levels. Policies aimed at targeting the lowest priced and illegal alcohols and reducing levels of harmful drinking should be a priority, especially in Lithuania.

Do inferences about mortality rates and disparities vary by source of mortality information?

PURPOSE: Researchers who study mortality among survey participants have multiple options for obtaining information about which participants died (and when and how they died). Some use public record and commercial databases; others use the National Death Index; some use the Social Security Death Master File; and still others triangulate sources and use Internet searches and genealogic methods. We ask how inferences about mortality rates and disparities depend on the choice of source of mortality information. METHODS: Using data on a large, nationally representative cohort of people who were first interviewed as high school sophomores in 1980 and for whom we have extensive identifying information, we describe mortality rates and disparities through about age 50 using four separate sources of mortality data. We rely on cross-tabular and multivariate logistic regression models. RESULTS: These sources of mortality information often disagree about which of our panelists died by about age 50 and also about overall mortality rates. However, differences in mortality rates (i.e., by sex, race/ethnicity, education) are similar across of sources of mortality data. CONCLUSION: Researchers' source of mortality information affects estimates of overall mortality rates but not estimates of differential mortality by sex, race and/or ethnicity, or education.

Opposing effects of mortality factors on progeny operational sex ratio may thwart adaptive manipulation of primary sex ratio.

Despite extensive research on mechanisms generating biases in sex ratios, the capacity of natural enemies to shift or further skew operational sex ratios following sex allocation and parental care remains largely unstudied in natural populations. Male cocoons of the sawfly Neodiprion abietis (Hymenoptera: Diprionidae) are consistently smaller than those of females, with very little overlap, and thus, we were able to use cocoon size to sex cocoons. We studied three consecutive cohorts of N. abietis in six forest stands to detect cocoon volume-associated biases in the attack of predators, pathogens, and parasitoids and examine how the combined effect of natural enemies shapes the realized operational sex ratio. Neodiprion abietis mortality during the cocoon stage was sex-biased, being 1.6 times greater for males than females. Greater net mortality in males occurred because male-biased mortality caused by a pteromalid parasitic wasp and a baculovirus was greater and more skewed than female-biased mortality caused by ichneumonid parasitic wasps. Variation in the susceptibility of each sex to each family of parasitoids was associated with differences in size and life histories of male and female hosts. A simulation based on the data indicated that shifts in the nature of differential mortality have different effects on the sex ratio and fitness of survivors. Because previous work has indicated that reduced host plant foliage quality induces female-biased mortality in this species, bottom-up and top-down factors acting on populations can affect operational sex ratios in similar or opposite ways. Shifts in ecological conditions therefore have the potential to alter progeny fitness and produce extreme sex ratio skews, even in the absence of unbalanced sex allocation. This would limit the capacity of females to anticipate the operational sex ratio and reliably predict the reproductive success of each gender at sex allocation.

Loss of largest and oldest individuals of the Montpellier snake correlates with recent warming in the southeastern Iberian Peninsula.

The effects of climate change on organisms are now being extensively studied in many different taxa. However, the variation in body size, usually shrinkage in response to increasing temperature, has received little attention regarding to reptiles. During past periods of global warming, many organisms shrank in size, and current evidence and experiments manipulating temperature have shown a biomass decrease in some organisms with increasing temperatures. Here we test whether the body size of the Montpellier snake Malpolon monspessulanus from the southeastern Iberian Peninsula is changing and correlated with the increasing temperature in this region during a 39-year period (1976-2014). We measured the snout-vent length (SVL) of vouchers in scientific collections to check for trends in adult body size at the population level in relation with temperature, while controlling for the age of the individuals (estimated by skeletochronology, n =141). Given the great ontogenetic variation in body size of the study species, we categorized age in 3 classes: "young adults" (under 5 years old), "intermediate adults" (from 5 to 7 years old), and "old adults" (from 8 to 14 years old). By means of linear mixed models, we found a negative relationship between SVL of "old adults" and average annual temperature in the region during the lifetime of each individual. Our results indicate that largest and oldest individuals of the Montpellier Snake, that is, males because of strong sexual size dimorphism in this species, disappeared from the study population, and suggest that it occurred in response to rising environmental temperature.