scholarly journals Impact of human mobility on the periodicities and mechanisms underlying measles dynamics

2015 ◽  
Vol 12 (104) ◽  
pp. 20141317 ◽  
Author(s):  
Ramona Marguta ◽  
Andrea Parisi
Keyword(s):  
Population Size ◽  
Parallel Computation ◽  
Human Mobility ◽  
Local Population ◽  
Sir Model ◽  
Global Level ◽  
Radiation Model ◽  
Stochastic Fluctuations ◽  
Measles Outbreaks ◽  
Disease Free

Three main mechanisms determining the dynamics of measles have been described in the literature: invasion in disease-free lands leading to import-dependent outbreaks, switching between annual and biennial attractors driven by seasonality, and amplification of stochastic fluctuations close to the endemic equilibrium. Here, we study the importance of the three mechanisms using a detailed geographical description of human mobility. We perform individual-based simulations of an SIR model using a gridded description of human settlements on top of which we implement human mobility according to the radiation model. Parallel computation permits detailed simulations of large areas. Focusing our research on the British Isles, we show that human mobility has an impact on the periodicity of measles outbreaks. Depending on the level of mobility, we observe at the global level multi-annual, annual or biennial cycles. The periodicity observed globally, however, differs from the local epidemic cycles: different locations show different mechanisms at work depending on both population size and mobility. As a result, the periodicities observed locally depend on the interplay between the local population size and human mobility.

scholarly journals Periodicity, synchronization and persistence in pre-vaccination measles

2016 ◽  
Vol 13 (119) ◽  
pp. 20160258 ◽  
Author(s):  
Ramona Marguta ◽  
Andrea Parisi
Keyword(s):  
Population Size ◽  
Human Mobility ◽  
Local Population ◽  
British Isles ◽  
Populated Area ◽  
Geographical Spread ◽  
Low Levels ◽  
The Relationship

We investigate the relationship between periodicity, synchronization and persistence of measles through simulations of geographical spread on the British Isles. We show that the establishment of areas of biennial periodicity depends on the interplay between human mobility and local population size and that locations undergoing biennial cycles tend to be, on average, synchronized in phase. We show however that occurrences of opposition of phase are actually quite common and correspond to stable dynamics. We also show that persistence is strictly related to circulation of the disease in the highly populated area of London and that this ensures survival of the disease even when human mobility drops to extremely low levels.

Adjustment of fecundity and sex ratio in response to social environments in a haplodiploid mite

2022 ◽  
Author(s):  
Nuwan Weerawansha ◽  
Qiao Wang ◽  
Xiong Zhao He
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Population Size ◽  
Local Population ◽  
Female Offspring ◽  
Social Environments ◽  
Positive Interaction ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Large Populations

Animals can adjust reproductive strategies in favour of corporation or competition in response to local population size and density, the two key factors of social environments. However, previous studies usually focus on either population size or density but ignore their interactions. Using a haplodiploid spider mite, Tetranychus ludeni Zacher, we carried out a factorial experiment in the laboratory to examine how ovipositing females adjust their fecundity and offspring sex ratio during their early reproductive life under various population size and density. We reveal that females laid significantly more eggs with increasing population size and significantly fewer eggs with increasing population density. This suggests that large populations favour cooperation between individuals and dense populations increase competition. We demonstrate a significant negative interaction of population size and density that resulted in significantly fewer eggs laid in the large and dense populations. Furthermore, we show that females significantly skewed the offspring sex ratio towards female-biased in small populations to reduce the local mate competition among their sons. However, population density incurred no significant impact on offspring sex ratio, while the significant positive interaction of population size and density significantly increased the proportion of female offspring in the large and dense populations, which will minimise food or space competition as females usually disperse after mating at crowded conditions. These results also suggest that population density affecting sex allocation in T. ludeni is intercorrelated with population size. This study provides evidence that animals can manipulate their reproductive output and adjust offspring sex ratio in response to various social environments, and the interactions of different socio-environmental factors may play significant roles.

scholarly journals Seasonal changes in distribution and abundance of a local Corncrake population

2020 ◽  
Author(s):  
Michał Budka ◽  
Patryk Kokociński ◽  
Paweł Bogawski ◽  
Maciej Nowak ◽  
Joanna Teresa Białas ◽  
...  
Keyword(s):  
Population Size ◽  
Breeding Season ◽  
Site Fidelity ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Local Population ◽  
Bird Species ◽  
Adult Males ◽  
Habitat Conditions ◽  
Population Declines

Abstract Many bird species have experienced short- or long-term population declines. However, the mechanisms and reasons underlying such negative changes are often not fully understood, making it difficult to identify effective conservation measures to recover populations. In this study, we focused on local changes in the abundance and distribution of calling male Corncrakes Crex crex in relation to: (1) within- and between-season site fidelity of adult males, (2) spatial distribution of territories in consecutive years and (3) the effect of habitat conditions on population size. We counted the number of calling males at ten randomly selected study plots (1 km2) in 2014–2018. Additionally, males were caught and individually marked in years 2015–2017. We found significant between-year changes in Corncrake abundance, from a 34% decrease to a 21% increase. On average, 32% of males established territories in the same locations as males recorded in the previous year. Breeding site fidelity was very low, with only 2–5% of males recaptured in the following year. Males selected areas characterized by higher values of NDVI (Normalized Difference Vegetation Index–higher values indicate more biomass) than on average within the study area. Population size in a particular year was significantly affected by the NDVI of the previous year but not by the NDVI in the current breeding season. We suppose that Corncrakes may exhibit a nomadic breeding behavior, and settle at territories when they encounter optimal habitat conditions. Moreover, as population size was negatively correlated with habitat conditions at the beginning of the previous breeding season, we suppose that local population changes may reflect more general trends in a whole population rather than local breeding success. Therefore, we highlight the need for better knowledge of Corncrake dispersal within the main European population and for the coordination of monitoring and conservation efforts, especially in those regions where most Corncrakes breed.

scholarly journals Modeling the epidemic dynamics of COVID-19: Agent-based approach including molecular dynamics simulation and SEIR type methods

2020 ◽  
Author(s):  
Amir Lohrasebi ◽  
Fatemeh Aghaei
Keyword(s):  
Human Mobility ◽  
Local Population ◽  
Dynamics Simulation ◽  
Agent Based ◽  
Epidemic Dynamics ◽  
Everyday Activities ◽  
Health Strategy ◽  
Virus Spreading ◽  
Flexible Model ◽  
Individual Human

Abstract In this study we developed a SEIR model, including social interactions and individual human mobility in everyday activities. For this purpose, daily mobility of people was considered by using the molecular dynamic method and the virus spreading was modeled employing the ordinary SEIR scheme. Utilizing this model, the variation of population size, density, and health strategy as well as the effect of busy places such as malls, were considered. The results show that, our flexible model is able to consider the effects of different parameters such as distance between peoples, local population density and health strategy in the outbreak.

scholarly journals Life histories predict genetic diversity and population structure within three species of Octopus targeted by small-scale fisheries in Northwest Mexico

2017 ◽  
Author(s):  
José F Domínguez-Contreras ◽  
Adrian Munguia-Vega ◽  
Bertha P Ceballos-Vázquez ◽  
Marcial Arellano-Martínez ◽  
Francisco J García-Rodríguez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Population Size ◽  
Effective Population Size ◽  
Gulf Of California ◽  
Life Histories ◽  
Local Population ◽  
Small Scale ◽  
Effective Population ◽  
Northwest Mexico

The fishery for octopus in Northwest Mexico has increased to over 2,000 tons annually, but to date the specific composition of the catch has been ignored. With at least three main species with varying life histories targeted by artisanal fisheries in the region, lack of information about the distribution of each species and metapopulation size and structure could impede effective fisheries management to avoid overexploitation. Here we tested if different life histories in three species of octopus help to predict observed patterns of genetic diversity, population dynamics, structure and connectivity that could be relevant to the sustainable management of the fishery. We sequenced two mitochondrial genes and genotyped seven nuclear microsatellite loci to identify the distribution of each species in 20 locations from the Gulf of California and the Pacific coast of the Baja California peninsula. We tested four a priori hypothesis derived from population genetic theory based on differences in the fecundity and dispersal potential for each species. We found that the species with low fecundity and without a planktonic larval stage (Octopus bimaculoides) had lower average effective population size and genetic diversity, but higher levels of kinship, population structure, and richness of private alleles, suggesting limited dispersal and high local recruitment. In contrast, two species with higher fecundity and planktonic larvae (O. bimaculatus, O. hubbsorum) showed higher effective population size and genetic diversity, and overall lower kinship and population structure, supporting higher levels of gene flow over a larger geographical scale. Even among the latter, there were differences in the calculated parameters possibly associated with increased connectivity in the species with the longest planktonic larval duration (O. bimaculatus). We consider that O. bimaculoides could be more susceptible to over exploitation of small, isolated populations that could have longer recovery times, and suggest that management should take place within each local population. For the two species with pelagic larvae, management should consider metapopulation structure over larger geographic scales and the directionality and magnitude of larval dispersal between localities driven by ocean currents. The distribution of each species and variations in their reproductive timing should also be considered when establishing marine reserves or seasonal fishing closures.

scholarly journals GENE FLOW AND GENETIC DIFFERENTIATION

Genetics ◽  
1974 ◽  
Vol 78 (3) ◽  
pp. 961-965
Author(s):  
P T Spieth
Keyword(s):  
Gene Flow ◽  
Genetic Differentiation ◽  
Population Size ◽  
Local Population ◽  
Biological Significance ◽  
Island Model ◽  
Genetic Identity ◽  
Biological Interpretation ◽  
Different Populations ◽  
Stepping Stone Model

ABSTRACT A brief analysis is presented for the effects of gene flow upon genetic differentiation within and between populations generated by mutation and drift. Previous results obtained with the "island" model are developed into a form that lends itself to biological interpretation. Attention is focused upon the effective local population size and the ratio of the genetic identity of two genes in different populations to that of two genes in the same population. The biological significance of this ratio, which is independent of population size, is discussed. Similarities between the results of this model and those of the "stepping-stone" model are noted.

scholarly journals Evidence of Co-Circulation of Multiples Arbovirus Transmitted by Aedes Sp. Based on Laboratorial Syndromic Surveillance At Health Unit in Slum Area of Federal District, Brazil

2021 ◽  
Author(s):  
Paulo Rufalco-Moutinho ◽  
Lorena Aparecida Gonçalves de Noronha ◽  
Tatyane de Souza Cardoso Quintão ◽  
Tayane Ferreira Nobre ◽  
Ana Paula Sampaio Cardoso ◽  
...  
Keyword(s):  
Syndromic Surveillance ◽  
Human Mobility ◽  
Local Population ◽  
Dengue Infection ◽  
Federal District ◽  
Health Unit ◽  
Slum Area ◽  
Significant Discrepancy ◽  
Epidemiologic Surveillance ◽  
Traditional Surveillance

Abstract Background: Mosquito-borne disease, especially arbovirus transmitted by Aedes mosquitoes, must be priority of Brazilian public health policies, mainly with others infectious agents in circulation. Laboratorial syndromic surveillance for fever or/and exanthematic acute syndrome was performed at health unit in slum area of Federal District. Methods: between June/2019 and March/2020, stopped by COVID-19 pandemic, 131 valid participants were identified and tested by RT-PCR for dengue (by serotype), chikungunya and Zika virus; and by serological IgM for dengue and chikungunya virus, with serologic assay performed when the participant did not present respiratory symptoms (cough or/and coryza). Results: 3 DENV-1 (2.3%), 4 DENV-2 (3%) and 1 CHIKV (0.7%) was lab-confirmed, showing evidence of hiperendemicity area even with the laboratorial syndromic surveillance not reaching the months of historical peak of dengue in Federal District (April-May). When compared the results of laboratorial syndromic surveillance with traditional epidemiologic surveillance data, is verified significant discrepancy between probable cases (from traditional surveillance) and lab-confirmed cases (from laboratorial syndromic surveillance). Conclusions: beyond the risks of local population are exposed, the socio-environment profile can be an able potential area to spread arbovirus, according to Aedes sp. dynamics and human mobility of the Federal District. Also, traditional surveillance may be misreporting probable cases for dengue infection, and underreporting confirmed cases for other arbovirus in the Federal District.

scholarly journals Global Stability of Vector-Host Disease with Variable Population Size

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Muhammad Altaf Khan ◽  
Saeed Islam ◽  
Sher Afzal Khan ◽  
Gul Zaman
Keyword(s):  
Global Stability ◽  
Population Size ◽  
Asymptotically Stable ◽  
Globally Asymptotically Stable ◽  
Host Disease ◽  
Variable Population ◽  
Globally Stable ◽  
Disease Free ◽  
Disease Persistence ◽  
Variable Population Size

The paper presents the vector-host disease with a variability in population. We assume, the disease is fatal and for some cases the infected individuals become susceptible. We first show the local and global stability of the disease-free equilibrium, for the case when, the disease free-equilibrium of the model is both locally as well as globally stable. For , the disease persistence occurs. The endemic equilibrium is locally as well as globally asymptotically stable for . Numerical results are presented for the justifications of theoratical results.

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