-
Proceedings. Biological Sciences Dec 2020Animals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit...
Animals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit immunologically and hygienically from cooperation, and individuals may alter their socio-spatial behaviour in response to infection, both of which could counteract density-related increases in exposure. Consequently, the costs and benefits of sociality for disease are often uncertain. Here, we use a long-term study of a wild European badger population () to investigate how within-population variation in host density determines infection with multiple parasites. Four out of five parasite taxa exhibited consistent spatial hotspots of infection, which peaked among badgers living in areas of low local population density. Combined movement, survival, spatial and social network analyses revealed that parasite avoidance was the likely cause of this negative density dependence, with possible roles for localized mortality, encounter-dilution effects, and micronutrient-enhanced immunity. These findings demonstrate that animals can organize their societies in space to minimize parasite infection, with important implications for badger behavioural ecology and for the control of badger-associated diseases.
Topics: Animals; Movement; Mustelidae; Population Density; Symbiosis
PubMed: 33323092
DOI: 10.1098/rspb.2020.2655 -
Theoretical Population Biology Dec 2022This study deals with the problem of the population shrinking in habitats affected by aging and excessive migration outflows. First, a control-oriented population...
This study deals with the problem of the population shrinking in habitats affected by aging and excessive migration outflows. First, a control-oriented population dynamics model was proposed that catches the effect of depopulation. The model also includes the effect of spatial interaction-driven migration flows on population size. The resulting model is a non-homogeneous ordinary differential equation. It includes such phenomena that are important from the control point of view, such as the influence of migration costs on population dynamics, the impact of aging on population size, or the effect of the habitats' carrying capacity on migration flows. Based on the model, controllability conditions are formulated and a control strategy was developed that is meant to avoid the depopulation of the habitat. The control method acts on the migration costs to achieve the control goal and requires only population size measurements. Simulation measurements are presented in the paper to show the effectiveness of the proposed modeling and control methods.
Topics: Population Dynamics; Population Density; Computer Simulation; Ecosystem; Conservation of Natural Resources
PubMed: 36379299
DOI: 10.1016/j.tpb.2022.11.002 -
The Journal of Heredity Mar 2021Genome studies of facultative sexual species, which can either reproduce sexually or asexually, are providing insight into the evolutionary consequences of mixed...
Genome studies of facultative sexual species, which can either reproduce sexually or asexually, are providing insight into the evolutionary consequences of mixed reproductive modes. It is currently unclear to what extent the evolutionary history of facultative sexuals' genomes can be approximated by the standard coalescent, and if a coalescent effective population size Ne exists. Here, I determine if and when these approximations can be made. When sex is frequent (occurring at a frequency much greater than 1/N per reproduction per generation, for N the actual population size), the underlying genealogy can be approximated by the standard coalescent, with a coalescent Ne≈N. When sex is very rare (at frequency much lower than 1/N), approximations for the pairwise coalescent time can be obtained, which is strongly influenced by the frequencies of sex and mitotic gene conversion, rather than N. However, these terms do not translate into a coalescent Ne. These results are used to discuss the best sampling strategies for investigating the evolutionary history of facultative sexual species.
Topics: Biological Evolution; Computer Simulation; Mitosis; Models, Genetic; Population Density; Reproduction; Sex
PubMed: 33511984
DOI: 10.1093/jhered/esaa036 -
Current Opinion in Psychology Apr 2020Has your environment become more crowded over time? Do you find yourself surrounded by mostly men or mostly women? Here, we review recent work on the psychological... (Review)
Review
Has your environment become more crowded over time? Do you find yourself surrounded by mostly men or mostly women? Here, we review recent work on the psychological effects of two key ecological dimensions: population density-the number of people in a given space-and sex ratio-the relative proportion of men to women in a group. Higher population densities are associated with a future-oriented psychology, increased educational investment, and a focus on 'quality over quantity' in family size and relationship preferences. Unequal sex ratios are associated with increased competition and risky behaviors amongst individuals of the more prevalent sex, and a general shift toward the relationship preferences of the scarcer sex.
Topics: Humans; Interpersonal Relations; Population Density; Sex Ratio; Social Behavior
PubMed: 31374451
DOI: 10.1016/j.copsyc.2019.06.015 -
Endocrinology Dec 2021
Topics: Endocrinology; Humans; Hypothalamo-Hypophyseal System; Population Density; Reproduction; Reproductive Health
PubMed: 34525211
DOI: 10.1210/endocr/bqab198 -
Ecology Feb 2019Spatially explicit capture-recapture (SECR) models have emerged as one solution to the problem of estimating the population density of mobile and cryptic animals....
Spatially explicit capture-recapture (SECR) models have emerged as one solution to the problem of estimating the population density of mobile and cryptic animals. Spatial models embody assumptions regarding the spatial distribution of individuals and the spatial detection process. The detection process is modeled in SECR as a radial decline in detection probability with distance from the activity center of each individual. This would seem to require that home ranges are circular. The robustness of SECR when home ranges are not circular has been the subject of conflicting statements. Ivan et al. previously compared the SECR density estimator to a telemetry-scaled non-spatial estimator. I suggest that the apparent non-robustness of SECR in their study was a simulation artefact. New simulations of elliptical home ranges establish that the SECR density estimator is largely robust to non-circularity when detectors are spread in two dimensions, but may be very biased if the detector array is linear and home ranges align with the array. Transformation to isotropy reduces bias from designs of intermediate dimension, such as hollow square arrays. Possible alignment of home ranges should be considered when designing detector arrays.
Topics: Animals; Homing Behavior; Population Density; Probability
PubMed: 30601582
DOI: 10.1002/ecy.2580 -
Prevention Science : the Official... Jul 2017AIDS stigmas delay HIV diagnosis, interfere with health care, and contribute to mental health problems among people living with HIV. While there are few studies of the...
AIDS stigmas delay HIV diagnosis, interfere with health care, and contribute to mental health problems among people living with HIV. While there are few studies of the geographical distribution of AIDS stigma, research suggests that AIDS stigmas are differentially experienced in rural and urban areas. We conducted computerized interviews with 696 men and women living with HIV in 113 different zip code areas that were classified as large-urban, small-urban, and rural areas in a southeast US state with high-HIV prevalence. Analyses conducted at the individual level (N = 696) accounting for clustering at the zip code level showed that internalized AIDS-related stigma (e.g., the sense of being inferior to others because of HIV) was experienced with greater magnitude in less densely populated communities. Multilevel models indicated that after adjusting for potential confounding factors, rural communities reported greater internalized AIDS-related stigma compared to large-urban areas and that small-urban areas indicated greater experiences of enacted stigma (e.g., discrimination) than large-urban areas. The associations between anticipated AIDS-related stigma (e.g., expecting discrimination) and population density at the community-level were not significant. Results suggest that people living in rural and small-urban settings experience greater AIDS-related internalized and enacted stigma than their counterparts living in large-urban centers. Research is needed to determine whether low-density population areas contribute to or are sought out by people who experienced greater AIDS-related stigma. Regardless of causal directions, interventions are needed to address AIDS-related stigma, especially among people in sparsely populated areas with limited resources.
Topics: Humans; Multivariate Analysis; Population Density; Rural Population; Social Stigma; Southeastern United States; Urban Population
PubMed: 28190136
DOI: 10.1007/s11121-017-0761-9 -
Ecology Sep 2018Dispersal is a key ecological process that influences the dynamics of spatially and socially structured populations and consists of three stages-emigration, transience,...
Dispersal is a key ecological process that influences the dynamics of spatially and socially structured populations and consists of three stages-emigration, transience, and settlement-and each stage is influenced by different social, individual, and environmental factors. Despite our appreciation of the complexity of the process, we lack a firm empirical understanding of the mechanisms underlying the different stages. Here, using data from 65 GPS-collared dispersing female coalitions of the cooperatively breeding meerkat (Suricata suricatta), we present a comprehensive analysis of the effects of population density, mate availability, dispersing coalition size, and individual factors on each of the three stages of dispersal in a wild population. We expected a positive effect of density on dispersal due to increased kin competition at high densities. We further anticipated positive effects of mate availability, coalition size, and body condition on dispersal success. We observed increasing daily emigration and settlement probabilities at high population densities. In addition, we found that emigration and settlement probabilities also increased at low densities and were lowest at medium densities. Daily emigration and settlement probabilities increased with increasing female coalition size and in the presence of unrelated males. Furthermore, the time individuals spent in the transient stage increased with population density, whereas coalition size and presence of unrelated males decreased dispersal distance. The observed nonlinear relationship between dispersal and population density is likely due to limited benefits of cooperation at low population densities and increased kin competition at high densities. Our study provides empirical validation for the theoretical predictions that population density is an important factor driving the evolution of delayed dispersal and philopatry in cooperative breeders.
Topics: Female; Humans; Male; Population Density; Population Dynamics; Reproduction
PubMed: 29934962
DOI: 10.1002/ecy.2433 -
Ecology Mar 2021Spatial capture-recapture (SCR) has emerged as the industry standard for estimating population density by leveraging information from spatial locations of repeat...
Spatial capture-recapture (SCR) has emerged as the industry standard for estimating population density by leveraging information from spatial locations of repeat encounters of individuals. The precision of density estimates depends fundamentally on the number and spatial configuration of traps. Despite this knowledge, existing sampling design recommendations are heuristic and their performance remains untested for most practical applications. To address this issue, we propose a genetic algorithm that minimizes any sensible, criteria-based objective function to produce near-optimal sampling designs. To motivate the idea of optimality, we compare the performance of designs optimized using three model-based criteria related to the probability of capture. We use simulation to show that these designs outperform those based on existing recommendations in terms of bias, precision, and accuracy in the estimation of population size. Our approach, available as a function in the R package oSCR, allows conservation practitioners and researchers to generate customized and improved sampling designs for wildlife monitoring.
Topics: Animals; Computer Simulation; Ecology; Population Density
PubMed: 33244753
DOI: 10.1002/ecy.3262 -
Nature Communications Feb 2022The spread of dengue and other arboviruses constitutes an expanding global health threat. The extensive heterogeneity in population distribution and potential complexity...
The spread of dengue and other arboviruses constitutes an expanding global health threat. The extensive heterogeneity in population distribution and potential complexity of movement in megacities of low and middle-income countries challenges predictive modeling, even as its importance to disease spread is clearer than ever. Using surveillance data at fine resolution from Rio de Janeiro, we document a scale-invariant pattern in the size of successive epidemics following DENV4 emergence. Using surveillance data at fine resolution following the emergence of the DENV4 dengue serotype in Rio de Janeiro, we document a pattern in the size of successive epidemics that is invariant to the scale of spatial aggregation. This pattern emerges from the combined effect of herd immunity and seasonal transmission, and is strongly driven by variation in population density at sub-kilometer scales. It is apparent only when the landscape is stratified by population density and not by spatial proximity as has been common practice. Models that exploit this emergent simplicity should afford improved predictions of the local size of successive epidemic waves.
Topics: Brazil; Dengue; Epidemics; Humans; Population Density; Serogroup
PubMed: 35194017
DOI: 10.1038/s41467-022-28231-w