scholarly journals Age-specific reproduction in a long-lived species: the combined effects of senescence and individual quality

2008 ◽  
Vol 275 (1637) ◽  
pp. 963-970 ◽  
Author(s):  
R.H McCleery ◽  
C.M Perrins ◽  
B.C Sheldon ◽  
A Charmantier
Keyword(s):  
Life Histories ◽  
Age Groups ◽  
Natural Populations ◽  
Population Level ◽  
Individual Performance ◽  
Laying Date ◽  
Loss Of Function ◽  
Breeding Performance ◽  
Differential Survival ◽  
Mute Swans

Apparent changes in breeding performance with age measured at the population level can be due to changes in individual capacity at different ages, or to the differential survival of individuals with different capabilities. Estimating the relative importance of the two is important for understanding ageing patterns in natural populations, but there are few studies of such populations in which these effects have been disentangled. We analysed laying date and clutch size as measures of individual performance in a population of mute swans ( Cygnus olor ) studied over 25 years at Abbotsbury, UK. On both measures of breeding performance, individuals tended to improve up to the age of 6 or 7, and to decline after about the age of 12. Individuals with longer lifespans performed better at all ages (earlier laying, larger clutches) than animals that ceased breeding earlier. We conclude that the apparent mean increase in performance with age in mute swans is due to both individual improvement and differential survival of individuals who perform well, while the decline in older age groups is due to individual loss of function. Our results underline the need to take individual differences into account when testing hypotheses about life histories in wild populations.

scholarly journals Population-level survey of loss-of-function mutations revealed that background dependent fitness genes are rare and functionally related in yeast

2021 ◽  
Author(s):  
Elodie Caudal ◽  
Anne Friedrich ◽  
Marion Garin ◽  
Jing Hou ◽  
Joseph Schacherer
Keyword(s):  
Genetic Background ◽  
Genetic Interaction ◽  
Natural Populations ◽  
Interaction Network ◽  
Population Level ◽  
Continuous Variation ◽  
Loss Of Function ◽  
Individual Level ◽  
Cytoplasmic Transport ◽  
Natural Isolates

AbstractIn natural populations, the same mutation can lead to different phenotypic outcomes due to the genetic variation that exists among individuals. Such genetic background effects are commonly observed, including in the context of many human diseases. However, systematic characterization of these effects at the species level is still lacking to date. Here, we sought to comprehensively survey background-dependent traits associated with gene loss-of-function (LoF) mutations in 39 natural isolates of Saccharomyces cerevisiae using a transposon saturation strategy. By analyzing the modeled fitness variability of a total of 4,469 genes, we found that 15% of them, when impacted by a LoF mutation, exhibited a significant gain- or loss-of-fitness phenotype in certain natural isolates compared to the reference strain S288C. Out of these 632 genetic background-dependent fitness genes identified, a total of 2/3 show a continuous variation across the population while 1/3 are specific to a single genetic background. Genes related to mitochondrial function are significantly overrepresented in the set of genes showing a continuous variation and display a potential functional rewiring with other genes involved in transcription and chromatin remodeling as well as in nuclear-cytoplasmic transport. Such rewiring effects are likely modulated by both the genetic background and the environment. While background-specific cases are rare and span diverse cellular processes, they can be functionally related at the individual level. All background-dependent fitness genes tend to have an intermediate connectivity in the global genetic interaction network and have shown relaxed selection pressure at the population level, highlighting their potential evolutionary characteristics.

scholarly journals Long-term social dynamics drive loss of function in pathogenic bacteria

2015 ◽  
Vol 112 (34) ◽  
pp. 10756-10761 ◽  
Author(s):  
Sandra Breum Andersen ◽  
Rasmus Lykke Marvig ◽  
Søren Molin ◽  
Helle Krogh Johansen ◽  
Ashleigh S. Griffin
Keyword(s):  
Social Interactions ◽  
Pathogenic Bacteria ◽  
Social Dynamics ◽  
Natural Populations ◽  
Population Level ◽  
Evolutionary Change ◽  
Bacterial Cells ◽  
Loss Of Function

Laboratory experiments show that social interactions between bacterial cells can drive evolutionary change at the population level, but significant challenges limit attempts to assess the relevance of these findings to natural populations, where selection pressures are unknown. We have increasingly sophisticated methods for monitoring phenotypic and genotypic dynamics in bacteria causing infectious disease, but in contrast, we lack evidence-based adaptive explanations for those changes. Evolutionary change during infection is often interpreted as host adaptation, but this assumption neglects to consider social dynamics shown to drive evolutionary change in vitro. We provide evidence to show that long-term behavioral dynamics observed in a pathogen are driven by selection to outcompete neighboring conspecific cells through social interactions. We find thatPseudomonas aeruginosabacteria, causing lung infections in patients with cystic fibrosis, lose cooperative iron acquisition by siderophore production during infection. This loss could be caused by changes in iron availability in the lung, but surprisingly, we find that cells retain the ability to take up siderophores produced by conspecifics, even after they have lost the ability to synthesize siderophores. Only when cooperative producers are lost from the population is the receptor for uptake lost. This finding highlights the potential pitfalls of interpreting loss of function in pathogenic bacterial populations as evidence for trait redundancy in the host environment. More generally, we provide an example of how sequence analysis can be used to generate testable hypotheses about selection driving long-term phenotypic changes of pathogenic bacteria in situ.

scholarly journals 214 Longitudinal Changes in Sleep Duration, Timing, Variability, and Stages during the COVID-19 Pandemic: Large-Scale Fitbit Data

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A86-A86
Author(s):  
Michael Grandner ◽  
Naghmeh Rezaei
Keyword(s):  
New York ◽  
Los Angeles ◽  
San Francisco ◽  
Sleep Duration ◽  
Large Scale ◽  
Age Groups ◽  
Population Level ◽  
Sleep Stages ◽  
Longitudinal Changes ◽  
Timing Variability

Abstract Introduction The COVID-19 pandemic has resulted in societal-level changes to sleep and other behavioral patterns. Objective, longitudinal data would allow for a greater understanding of sleep-related changes at the population level. Methods N= 163,524 deidentified active Fitbit users from 6 major US cities contributed data, representing areas particularly hard-hit by the pandemic (Chicago, Houston, Los Angeles, New York, San Francisco, and Miami). Sleep variables extracted include nightly and weekly mean sleep duration and bedtime, variability (standard deviation) of sleep duration and bedtime, and estimated arousals and sleep stages. Deviation from similar timeframes in 2019 were examined. All analyses were performed in Python. Results These data detail how sleep duration and timing changed longitudinally, stratified by age group and gender, relative to previous years’ data. Overall, 2020 represented a significant departure for all age groups and both men and women (P<0.00001). Mean sleep duration increased in nearly all groups (P<0.00001) by 5-11 minutes, compared to a mean decrease of 5-8 minutes seen over the same period in 2019. Categorically, sleep duration increased for some and decreased for others, but more extended than restricted. Sleep phase shifted later for nearly all groups (p<0.00001). Categorically, bedtime was delayed for some and advanced for others, though more delayed than advanced. Duration and bedtime variability decreased, owing largely to decreased weekday-weekend differences. WASO increased, REM% increased, and Deep% decreased. Additional analyses show stratified, longitudinal changes to sleep duration and timing mean and variability distributions by month, as well as effect sizes and correlations to other outcomes. Conclusion The pandemic was associated with increased sleep duration on average, in contrast to 2019 when sleep decreased. The increase was most profound among younger adults, especially women. The youngest adults also experienced the greatest bedtime delay, in line with extensive school-start-times and chronotype data. When given the opportunity, the difference between weekdays and weekends became smaller, with occupational implications. Sleep staging data showed that slightly extending sleep minimally impacted deep sleep but resulted in a proportional increase in REM. Wakefulness during the night also increased, suggesting increased arousal despite greater sleep duration. Support (if any) This research was supported by Fitbit, Inc.

scholarly journals Evaluation of vaccines against enteric infections: a clinical and public health research agenda for developing countries

2011 ◽  
Vol 366 (1579) ◽  
pp. 2799-2805 ◽  
Author(s):  
John Clemens
Keyword(s):  
Public Health ◽  
Developing Countries ◽  
Age Groups ◽  
Population Level ◽  
Vaccine Safety ◽  
Public Health Research ◽  
Protective Effects ◽  
Vaccine Protection ◽  
Enteric Infections ◽  
Research Questions

Enteric infections are a major cause of morbidity and mortality in developing countries. To date, vaccines have played a limited role in public health efforts to control enteric infections. Licensed vaccines exist for cholera and typhoid, but these vaccines are used primarily for travellers; and there are two internationally licensed vaccines for rotavirus, but they are mainly used in affluent countries. The reasons that enteric vaccines are little used in developing countries are multiple, and certainly include financial and political constraints. Also important is the need for more cogent evidence on the performance of enteric vaccines in developing country populations. A partial inventory of research questions would include: (i) does the vaccine perform well in the most relevant settings? (ii) does the vaccine perform well in all epidemiologically relevant age groups? (iii) is there adequate evidence of vaccine safety once the vaccines have been deployed in developing countries? (iv) how effective is the vaccine when given in conjunction with non-vaccine cointerventions? (v) what is the level of vaccine protection against all relevant outcomes? and (vi) what is the expected population level of vaccine protection, including both direct and herd vaccine protective effects? Provision of evidence addressing these questions will help expand the use of enteric vaccines in developing countries.

scholarly journals Perspectives from animal demography on incorporating evolutionary mechanism into plant population dynamics

2018 ◽  
Author(s):  
Maria Paniw
Keyword(s):  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Population Level ◽  
Plant Population ◽  
Future Research ◽  
Phenotypic Traits ◽  
Plant Population Dynamics ◽  
Future Research Agenda ◽  
Powerful Approach

AbstractWith a growing number of long-term, individual-based data on natural populations available, it has become increasingly evident that environmental change affects populations through complex, simultaneously occurring demographic and evolutionary processes. Analyses of population-level responses to environmental change must therefore integrate demography and evolution into one coherent framework. Integral projection models (IPMs), which can relate genetic and phenotypic traits to demographic and population-level processes, offer a powerful approach for such integration. However, a rather artificial divide exists in how plant and animal population ecologists use IPMs. Here, I argue for the integration of the two sub-disciplines, particularly focusing on how plant ecologists can diversify their toolset to investigate selection pressures and eco-evolutionary dynamics in plant population models. I provide an overview of approaches that have applied IPMs for eco-evolutionary studies and discuss a potential future research agenda for plant population ecologists. Given an impending extinction crisis, a holistic look at the interacting processes mediating population persistence under environmental change is urgently needed.

scholarly journals Vaccinating Adolescents and Children Significantly Reduces COVID-19 Morbidity and Mortality across All Ages: A Popula-Tion-Based Modeling Study Using the UK as an Example

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1180
Author(s):  
Tinevimbo Shiri ◽  
Marc Evans ◽  
Carla A. Talarico ◽  
Angharad R. Morgan ◽  
Maaz Mussad ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Age Groups ◽  
Population Level ◽  
Vital Role ◽  
Morbidity And Mortality ◽  
Transmission Model ◽  
Base Case ◽  
Global Public Health ◽  
The Uk ◽  
The Impact

Debate persists around the risk–benefit balance of vaccinating adolescents and children against COVID-19. Central to this debate is quantifying the contribution of adolescents and children to the transmission of SARS-CoV-2, and the potential impact of vaccinating these age groups. In this study, we present a novel SEIR mathematical disease transmission model that quantifies the impact of different vaccination strategies on population-level SARS-CoV-2 infections and clinical outcomes. The model employs both age- and time-dependent social mixing patterns to capture the impact of changes in restrictions. The model was used to assess the impact of vaccinating adolescents and children on the natural history of the COVID-19 pandemic across all age groups, using the UK as an example. The base case model demonstrates significant increases in COVID-19 disease burden in the UK following a relaxation of restrictions, if vaccines are limited to those ≥18 years and vulnerable adolescents (≥12 years). Including adolescents and children in the vaccination program could reduce overall COVID-related mortality by 57%, and reduce cases of long COVID by 75%. This study demonstrates that vaccinating adolescents and children has the potential to play a vital role in reducing SARS-CoV-2 infections, and subsequent COVID-19 morbidity and mortality, across all ages. Our results have major global public health implications and provide valuable information to inform a potential pandemic exit strategy.

scholarly journals Effectiveness of live attenuated monovalent human rotavirus vaccination in rural Ecuador, 2008-2013

2018 ◽  
Author(s):  
Alicia N. M. Kraay ◽  
Edward L. Ionides ◽  
Gwenyth O. Lee ◽  
William F. Cevallos Trujillo ◽  
Joseph N.S. Eisenberg
Keyword(s):  
Indirect Effects ◽  
Cox Regression ◽  
Age Groups ◽  
Community Setting ◽  
Population Level ◽  
Population Based ◽  
Case Control ◽  
Rotavirus Infection ◽  
Human Rotavirus ◽  
Overall Effectiveness

AbstractBackgroundWhile live attenuated monovalent human rotavirus vaccine (Rotarix) efficacy has been characterized through randomized studies, its effectiveness, especially in non-clinical settings, is unclear. In this study, we estimate direct, indirect, and overall effectiveness of Rotarix vaccination.MethodsWe analyze 29 months of all-cause diarrhea surveillance from a child cohort (n=376) and ten years of serial population-based case-control lab-confirmed rotavirus data (n=2489) from rural Ecuador during which Rotarix vaccination was introduced. We estimate: 1) the direct effect of vaccination from a cohort of children born from 2008-2013 using Cox regression to compare time to first all-cause diarrhea case by vaccine status; and 2) the overall effect on all-cause diarrheal and symptomatic and asymptomatic rotavirus infection for all age groups, including indirect effects on adults, from the case-control data using weighted logistic regression.ResultsRotarix vaccination provided direct protection against all-cause diarrhea among children 0.5 - 2 years (All-cause diarrhea reduction for receipt of 2 doses of Rotarix=57.1%, 95% CI: 16.6, 77.9%). Overall effectiveness against rotavirus infection was strong (Exposure to 100% coverage of Rotarix vaccination was associated with an 85.5% reduction, 95% CI: 61.1-94.6%) compared to 0% coverage. Indirect effects were observed among older, vaccine-ineligible children and adults (84.5% reduction, 95% CI: 48.2-95.4%). Vaccine effectiveness was high against both symptomatic (48.3% reduction,95% CI: 0.03-73.1%) and asymptomatic infection (90.1% reduction, 95% CI: 56.9-97.7%).ConclusionsRotarix vaccination suppresses overall transmission. It is highly effective among children in a rural community setting and provides population-level benefits through indirect protection among adults.

scholarly journals You aren't what you eat, you become what you eat

2021 ◽  
Author(s):  
Christopher R Stephens ◽  
Jonathan F Easton ◽  
Heriberto Roman Sicilia
Keyword(s):  
Weight Gain ◽  
Energy Intake ◽  
Energy Gap ◽  
Age Groups ◽  
Population Level ◽  
Energy Imbalance ◽  
Obesity Epidemic ◽  
Daily Energy ◽  
Large Populations ◽  
Energy Excess

Obesity (and the consequent obesity epidemic) is a complex, adaptive process, taking place over a time span of many years. Energy intake is recognized as a potentially important driver of obesity, especially in the context of an identifiable energy imbalance which, it is surmised, must lead to weight gain. Similarly, energy expenditure must play an important role. However, both show an enormous degree of individual variation. Therefore, measuring them is an exceedingly difficult task, especially in the context of large populations and long time periods. It has been argued that population-level observed weight gain can be traced back to very small daily energy imbalances while, at the same time, positing that a much larger maintenance energy gap is responsible for maintaining the energy requirements of the increased weight population. In this paper we examine the relation between BMI and energy intake as functions of age. The convexity of the BMI curves as a function of age and gender demonstrate the enhanced obesity risk apparent in young adults and women, and imply that no settling points exist at the population level. Consistent with other studies, overall weight increases are consistent with a very small daily energy imbalance, about 7 cal. Consumption as a function of age shows a small, steady, linear decrease of about 8 cal per year, and can be associated with a maximal energy excess/deficit of about 250cal for the youngest and oldest age groups. By examining weight differences between age groups as a function of age, we argue that this excess/deficit is an important motor for the observed weight differences, and argue that the apparent energy imbalance of 250 cal, due to excess consumption, leads to an effective imbalance of only 7 cal due to the existence of various physiological and behavioral mechanisms that enhance weight homeostasis and effectively reduce the energy excess from 250 cal to 7 cal. We discuss several possibilities for such mechanisms.

scholarly journals Comparative analysis of the ftness of Drosophila virilis lines contrasting in response to stress

2019 ◽  
Vol 22 (8) ◽  
pp. 1090-1096
Author(s):  
E. K. Karpova ◽  
I. Yu. Rauschenbach ◽  
N. E. Gruntenko
Keyword(s):  
Heat Stress ◽  
Natural Populations ◽  
Population Level ◽  
Stress Reaction ◽  
Egg Laying ◽  
Drosophila Virilis ◽  
Gonadotropic Hormone ◽  
Adverse Conditions ◽  
Low Intensity ◽  
Response To Stress

One of the crucial elements contributing to the adaptation of organisms to unfavorable environmental conditions is the reaction of stress. The study of its genetic control and role in adaptation to unfavorable conditions are of special interest. The juvenile hormone (JH) acts as a gonadotropic hormone in adult insects controlling the development of the ovaries, inducing vitellogenesis and oviposition. It was shown that a decrease in JH degradation in individuals reacting to adverse conditions by stress reaction (R­individuals) causes delay in egg laying and seems to allow the population to “wait out” the unfavorable conditions, thereby contributing to the adaptation at the population level. However, monitoring natural populations of D. melanogaster for the capability of stress reaction demonstrated that they have a high percentage of individuals incapable of it (NR­individuals). The study of reproductive characteristics of R­ and NR­individuals showed that under normal conditions R­individuals have the advantage of procreating offspring. Under unfavorable conditions, if the stressor is intense enough, NR­individuals die, but if its intensity is low, then they, unlike R­individuals, continue to produce offspring. Based on these data, it was hypothesized that the balance of R­ and NR­alleles in the population ensures its adaptation under frequent stresses of low intensity. To verify the hypothesis by an experiment, the ftness characteristics (lifespan, fecundity) of the R and NR lines of D. virilis were studied under normal conditions and under regular heat stress of various frequency.

scholarly journals Introduction. Antarctic ecology: from genes to ecosystems. Part 2. Evolution, diversity and functional ecology

2007 ◽  
Vol 362 (1488) ◽  
pp. 2187-2189 ◽  
Author(s):  
Alex D Rogers ◽  
Eugene J Murphy ◽  
Nadine M Johnston ◽  
Andrew Clarke
Keyword(s):  
Climate Change ◽  
Life Histories ◽  
Natural Populations ◽  
Environmental Parameters ◽  
Functional Ecology ◽  
Antarctic Species ◽  
Trade Offs ◽  
Genes To Ecosystems ◽  
Micro Organisms ◽  
The Antarctic

The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.

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