Spatial memory shapes density dependence in population dynamics

Most population dynamics studies assume that individuals use space uniformly, and thus mix well spatially. In numerous species, however, individuals do not move randomly, but use spatial memory to visit renewable resource patches repeatedly. To understand the extent to which memory-based foraging movement may affect density-dependent population dynamics through its impact on competition, we developed a spatially explicit, individual-based movement model where reproduction and death are functions of foraging efficiency. We compared the dynamics of populations of with- and without-memory individuals. We showed that memory-based movement leads to a higher population size at equilibrium, to a higher depletion of the environment, to a marked discrepancy between the global (i.e. measured at the population level) and local (i.e. measured at the individual level) intensities of competition, and to a nonlinear density dependence. These results call for a deeper investigation of the impact of individual movement strategies and cognitive abilities on population dynamics.

Download Full-text

Modelling the HIV-Associated TB Epidemic and the Impact of Interventions Aimed at Epidemic Control

HIV and Tuberculosis ◽

10.1007/978-3-030-29108-2_3 ◽

2019 ◽

pp. 25-55

Author(s):

P. J. Dodd ◽

C. Pretorius ◽

B. G. Williams

Keyword(s):

Natural History ◽

Mathematical Models ◽

Population Level ◽

Explicit Representation ◽

Epidemic Control ◽

Future Directions ◽

Individual Level ◽

Tuberculosis Epidemiology ◽

History Of ◽

The Impact

Abstract In this chapter, we focus on mathematical models of tuberculosis epidemiology (TB) that include interactions with HIV and an explicit representation of transmission. We review the natural history of TB and illustrate how its features are simplified and incorporated in mathematical models. We then review the ways HIV influences the natural history of TB, the interventions that have been considered in models, and the way these individual-level effects are represented in models. We then go on to consider population-level effects, reviewing the TB/HIV modelling literature. We first review studies whose focus was on purely epidemiological modelling, and then studies whose focus was on modelling the impact of interventions. We conclude with a summary of the uses and achievements of TB/HIV modelling and some suggested future directions.

Download Full-text

Analyzing 24-Hour Blood Pressure Measurements with a Novel Cuffless Pulse Transit Time Device in Clinical Practice—Does the Software for Heartbeat Detection Matter?

Diagnostics ◽

10.3390/diagnostics10060361 ◽

2020 ◽

Vol 10 (6) ◽

pp. 361

Author(s):

Leo Kilian ◽

Philipp Krisai ◽

Thenral Socrates ◽

Christian Arranto ◽

Otmar Pfister ◽

...

Keyword(s):

Blood Pressure ◽

Transit Time ◽

Pulse Transit Time ◽

Population Level ◽

Raw Data ◽

Invasive Blood Pressure ◽

Individual Level ◽

Non Invasive ◽

The Individual ◽

The Impact

Background: The Somnotouch-Non-Invasive-Blood-Pressure (NIBP) device delivers raw data consisting of electrocardiography and photoplethysmography for estimating blood pressure (BP) over 24 h using pulse-transit-time. The study’s aim was to analyze the impact on 24-hour BP results when processing raw data by two different software solutions delivered with the device. Methods: We used data from 234 participants. The Somnotouch-NIBP measurements were analyzed using the Domino-light and Schiller software and compared. BP values differing >5 mmHg were regarded as relevant and explored for their impact on BP classification (normotension vs. hypertension). Results: Mean (±standard deviation) absolute systolic/diastolic differences for 24-hour mean BP were 1.5 (±1.7)/1.1 (±1.3) mm Hg. Besides awake systolic BP (p = 0.022), there were no statistically significant differences in systolic/diastolic 24-hour mean, awake, and asleep BP. Twenty four-hour mean BP agreement (number (%)) between the software solutions within 5, 10, and 15 mmHg were 222 (94.8%), 231 (98.7%), 234 (100%) for systolic and 228 (97.4%), 232 (99.1%), 233 (99.5%) for diastolic measurements, respectively. A BP difference of >5 mmHg was present in 24 (10.3%) participants leading to discordant classification in 4–17%. Conclusion: By comparing the two software solutions, differences in BP are negligible at the population level. However, at the individual level there are, in a minority of cases, differences that lead to different BP classifications, which can influence the therapeutic decision.

Download Full-text

A Simplified Population-Level Landscape Model Identifying Ecological Risk Drivers of Pesticide Applications, Part One: Case Study for Large Herbivorous Mammals

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18157720 ◽

2021 ◽

Vol 18 (15) ◽

pp. 7720

Author(s):

David Tarazona ◽

Guillermo Tarazona ◽

Jose V. Tarazona

Keyword(s):

Population Dynamics ◽

Pesticide Exposure ◽

Population Level ◽

Guidance Document ◽

Population Abundance ◽

Landscape Model ◽

Ecological Data ◽

Conceptual Approach ◽

Terrestrial Vertebrates ◽

The Impact

Environmental risk assessment is a key process for the authorization of pesticides, and is subjected to continuous challenges and updates. Current approaches are based on standard scenarios and independent substance-crop assessments. This arrangement does not address the complexity of agricultural ecosystems with mammals feeding on different crops. This work presents a simplified model for regulatory use addressing landscape variability, co-exposure to several pesticides, and predicting the effect on population abundance. The focus is on terrestrial vertebrates and the aim is the identification of the key risk drivers impacting on mid-term population dynamics. The model is parameterized for EU assessments according to the European Food Safety Authority (EFSA) Guidance Document, but can be adapted to other regulatory schemes. The conceptual approach includes two modules: (a) the species population dynamics, and (b) the population impact of pesticide exposure. Population dynamics is modelled through daily survival and seasonal reproductions rates; which are modified in case of pesticide exposure. All variables, parameters, and functions can be modified. The model has been calibrated with ecological data for wild rabbits and brown hares and tested for two herbicides, glyphosate and bromoxynil, using validated toxicity data extracted from EFSA assessments. Results demonstrate that the information available for a regulatory assessment, according to current EU information requirements, is sufficient for predicting the impact and possible consequences at population dynamic levels. The model confirms that agroecological parameters play a key role when assessing the effect of pesticide exposure on population abundance. The integration of laboratory toxicity studies with this simplified landscape model allows for the identification of conditions leading to population vulnerability or resilience. An Annex includes a detailed assessment of the model characteristics according to the EFSA scheme on Good Modelling Practice.

Download Full-text

Private Religious or Spiritual Activities and its Impact on Life Satisfaction: A Population-based Study

10.31219/osf.io/cvda6 ◽

2019 ◽

Author(s):

Sameer Desai

Keyword(s):

Life Satisfaction ◽

Multinomial Logistic Regression ◽

Population Level ◽

Well Being ◽

Canadian Community Health Survey ◽

Population Based ◽

Multinomial Logistic Regression Analysis ◽

Individual Level ◽

High Satisfaction ◽

The Impact

Background: Life satisfaction is considered a valid population-based indicator of health and well-being. Recently, many advances in life satisfaction and well-being have been made by improving social and health policies. However, several countries continue to report low levels of life satisfaction, even among many modern industrialized nations. The purpose of this study was to investigate the impact of private religious or spiritual activities (PRS) as a possible modifiable, individual-level factor to increase life satisfaction, with population-level health implications.Methods: The analytic sample included 9,627 respondents to the 2011-2012 Canadian Community Health Survey. Multinomial logistic regression analysis was conducted to examine the relationship between self-reported PRS activities and life satisfaction, adjusted for confounders.Results: After adjusting for the confounders, daily PRS activities was associated with an increased odds of high satisfaction (AOR=1.22, 95% CI: 0.84, 1.78) compared to low satisfaction. Engaging in weekly PRS activities was also associated with an increased odds of high satisfaction (AOR = AOR=1.33, 95% CI: 0.87, 2.02) compared to low satisfaction. Monthly engagement in PRS activities was not associated with increases in life satisfaction. Conclusions: There is a moderate association between the odds of high satisfaction and engaging in PRS activities on a daily or weekly basis. The variability in the CIs of the AORs indicates imprecision in the data; however, the majority of the possible range of effects are beneficial. Countries and other relevant organizations should be cognizant of the possible role that religious and spiritual values may have on life satisfaction, as another factor to explore further for population-level health benefits.

Download Full-text

The Normative Underpinnings of Population-Level Alcohol Use: An Individual-Level Simulation Model

Health Education & Behavior ◽

10.1177/1090198119880545 ◽

2020 ◽

Vol 47 (2) ◽

pp. 224-234

Author(s):

Charlotte Probst ◽

Tuong Manh Vu ◽

Joshua M. Epstein ◽

Alexandra E. Nielsen ◽

Charlotte Buckley ◽

...

Keyword(s):

Alcohol Use ◽

Social Norms ◽

Drinking Behavior ◽

Population Level ◽

Drinking Patterns ◽

Individual Level ◽

Behavioral Rules ◽

Level Model ◽

The Individual ◽

The Impact

Background. By defining what is “normal,” appropriate, expected, and unacceptable, social norms shape human behavior. However, the individual-level mechanisms through which social norms impact population-level trends in health-relevant behaviors are not well understood. Aims. To test the ability of social norms mechanisms to predict changes in population-level drinking patterns. Method. An individual-level model was developed to simulate dynamic normative mechanisms and behavioral rules underlying drinking behavior over time. The model encompassed descriptive and injunctive drinking norms and their impact on frequency and quantity of alcohol use. A microsynthesis initialized in 1979 was used as a demographically representative synthetic U.S. population. Three experiments were performed in order to test the modelled normative mechanisms. Results. Overall, the experiments showed limited influence of normative interventions on population-level alcohol use. An increase in the desire to drink led to the most meaningful changes in the population’s drinking behavior. The findings of the experiments underline the importance of autonomy, that is, the degree to which an individual is susceptible to normative influence. Conclusion. The model was able to predict theoretically plausible changes in drinking patterns at the population level through the impact of social mechanisms. Future applications of the model could be used to plan norms interventions pertaining to alcohol use as well as other health behaviors.

Download Full-text

The population dynamics of competition between parasites

Parasitology ◽

10.1017/s0031182000057401 ◽

1985 ◽

Vol 91 (2) ◽

pp. 317-347 ◽

Cited By ~ 124

Author(s):

A. P. Dobson

Keyword(s):

Population Dynamics ◽

Parasite Species ◽

Interference Competition ◽

Population Level ◽

Experimental Tests ◽

Theoretical Models ◽

Control Agent ◽

Host Population ◽

Free Living ◽

The Impact

A number of published studies of competition between parasite species are examined and compared. It is suggested that two general levels of interaction are discernible: these correspond to the two levels of competition recognized by workers studying free-living animals and plants: ‘exploitation’ and ‘interference’ competition. The former may be defined as the joint utilization of a host species by two or more parasite species, while the latter occurs when antagonistic mechanisms are utilized by one species either to reduce the survival or fecundity of a second species or to displace it from a preferred site of attachment. Data illustrating both levels of interaction are collated from a survey of the published literature and these suggest that interference competition invariably operates asymmetrically. The data are also used to estimate a number of population parameters which are important in determining the impact of competition at the population level. Theoretical models of host-parasite associations for both classes of competition are used to examine the expected patterns of population dynamics that will be exhibited by simple two-species communities of parasites that utilize the same host population. The analysis suggests that the most important factor allowing competing species of parasites to coexist is the statistical distribution of the parasites within the host population. A joint stable equilibrium should be possible if both species are aggregated in their distribution. The size of the parasite burdens at equilibrium is then determined by other life-history parameters such as pathogenicity, rates of resource utilization and antagonistic ability. Comparison of these theoretical expectations with a variety of sets of empirical data forms the basis for a discussion about the importance of competition in natural parasite populations. The models are used to assess quantitatively the potential for using competing parasite species as biological control agents for pathogens of economic or medical importance. The most important criterion for identifying a successful control agent is an ability to infect a high proportion of the host population. If such a parasite species also exhibits an intermediate level of pathology or an efficient ability to utilize shared common resources, antagonistic interactions between the parasite species contribute only secondarily to the success of the control. Competition in parasites is compared with competition in free-living animals and plants. The comparison suggests further experimental tests which may help to assess the importance of competition in determining the structure of more complex parasite-host communities.

Download Full-text

Impact of increasing vegetarian availability on meal selection and sales in cafeterias

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1907207116 ◽

2019 ◽

Vol 116 (42) ◽

pp. 20923-20929 ◽

Cited By ~ 19

Author(s):

Emma E. Garnett ◽

Andrew Balmford ◽

Chris Sandbrook ◽

Mark A. Pilling ◽

Theresa M. Marteau

Keyword(s):

Large Scale ◽

Population Level ◽

Field Studies ◽

Individual Level ◽

Rebound Effects ◽

Percentage Points ◽

Physical Environments ◽

Meat Meal ◽

Level Data ◽

The Impact

Shifting people in higher income countries toward more plant-based diets would protect the natural environment and improve population health. Research in other domains suggests altering the physical environments in which people make decisions (“nudging”) holds promise for achieving socially desirable behavior change. Here, we examine the impact of attempting to nudge meal selection by increasing the proportion of vegetarian meals offered in a year-long large-scale series of observational and experimental field studies. Anonymized individual-level data from 94,644 meals purchased in 2017 were collected from 3 cafeterias at an English university. Doubling the proportion of vegetarian meals available from 25 to 50% (e.g., from 1 in 4 to 2 in 4 options) increased vegetarian meal sales (and decreased meat meal sales) by 14.9 and 14.5 percentage points in the observational study (2 cafeterias) and by 7.8 percentage points in the experimental study (1 cafeteria), equivalent to proportional increases in vegetarian meal sales of 61.8%, 78.8%, and 40.8%, respectively. Linking sales data to participants’ previous meal purchases revealed that the largest effects were found in the quartile of diners with the lowest prior levels of vegetarian meal selection. Moreover, serving more vegetarian options had little impact on overall sales and did not lead to detectable rebound effects: Vegetarian sales were not lower at other mealtimes. These results provide robust evidence to support the potential for simple changes to catering practices to make an important contribution to achieving more sustainable diets at the population level.

Download Full-text

The impact of behavioral plasticity at individual level on domestic cat population dynamics

Ecological Modelling ◽

10.1016/s0304-3800(00)00285-4 ◽

2000 ◽

Vol 133 (1-2) ◽

pp. 117-124 ◽

Cited By ~ 16

Author(s):

Dominique Pontier ◽

Pierre Auger ◽

Rafael Bravo de la Parra ◽

Eva Sánchez

Keyword(s):

Population Dynamics ◽

Behavioral Plasticity ◽

Domestic Cat ◽

Individual Level ◽

The Impact

Download Full-text

On the Apportionment of Archaic Human Diversity

10.1101/2021.07.15.452563 ◽

2021 ◽

Author(s):

Fernando A Villanea ◽

Kelsey E Witt ◽

Elle Loughran ◽

Emilia A Huerta-Sanchez

Keyword(s):

South Asians ◽

Demographic History ◽

Population Level ◽

Modern Human ◽

East Asians ◽

Individual Level ◽

Archaic Admixture ◽

Human Relatedness ◽

The Individual ◽

The Impact

The apportionment of human genetic diversity within and between populations has been measured to understand human relatedness and demographic history. Likewise, the distribution of archaic ancestry in modern populations can be leveraged to better understand the interaction between our species and its archaic relatives, and the impact of natural selection on archaic segments of the human genome. Resolving these interactions can be difficult, as archaic variants in modern populations have also been shaped by genetic drift, bottlenecks, and gene flow. Here, we investigate the apportionment of archaic variation in Eurasian populations. We find that archaic genome coverage at the individual- and population-level present unique patterns in modern human population: South Asians have an elevated count of population-unique archaic SNPs, and Europeans and East Asians have a higher degree of archaic SNP sharing, indicating that population demography and archaic admixture events had distinct effects in these populations. We confirm previous observations that East Asians have more Neanderthal ancestry than Europeans at an individual level, but surprisingly Europeans have more Neandertal ancestry at a population level. In comparing these results to our simulated models, we conclude that these patterns likely reflect a complex series of interactions between modern humans and archaic populations.

Download Full-text

African Gene Flow Reduces Beta-Ionone Anosmia/Hyposmia Prevalence in Admixed Malagasy Populations

Brain Sciences ◽

10.3390/brainsci11111405 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1405

Author(s):

Harilanto Razafindrazaka ◽

Veronica Pereda-Loth ◽

Camille Ferdenzi ◽

Margit Heiske ◽

Omar Alva ◽

...

Keyword(s):

Gene Flow ◽

African Ancestry ◽

Sensory Perception ◽

Population Level ◽

P Value ◽

Individual Level ◽

Specific Anosmia ◽

Odorant Molecule ◽

The Individual ◽

The Impact

While recent advances in genetics make it possible to follow the genetic exchanges between populations and their phenotypic consequences, the impact of the genetic exchanges on the sensory perception of populations has yet to be explored. From this perspective, the present study investigated the consequences of African gene flow on odor perception in a Malagasy population with a predominantly East Asian genetic background. To this end, we combined psychophysical tests with genotype data of 235 individuals who were asked to smell the odorant molecule beta-ionone (βI). Results showed that in this population the ancestry of the OR5A1 gene significantly influences the ability to detect βI. At the individual level, African ancestry significantly protects against specific anosmia/hyposmia due to the higher frequency of the functional gene (OR ratios = 14, CI: 1.8–110, p-value = 0.012). At the population level, African introgression decreased the prevalence of specific anosmia/hyposmia to this odorous compound. Taken together, these findings validate the conjecture that in addition to cultural exchanges, genetic transfer may also influence the sensory perception of the population in contact.

Download Full-text