THE INTERACTING EFFECTS OF PRICES AND WEATHER ON POPULATION CYCLES IN A PREINDUSTRIAL COMMUNITY

1998 ◽  
Vol 30 (1) ◽  
pp. 15-32 ◽  
Author(s):  
SUSAN SCOTT ◽  
S. R. DUNCAN ◽  
C. J. DUNCAN
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Short Wavelength ◽  
Population Cycles ◽  
Adult Mortality ◽  
Epidemic Disease ◽  
And Migration ◽  
First Year Of Life ◽  
Migratory Movements ◽  
Grain Prices

The exogenous cycles and population dynamics of the community at Penrith, Cumbria, England, have been studied (1557-1812) using aggregative analysis, family reconstitution and time series analysis. This community was living under marginal conditions for the first 200 years and the evidence presented is of a homeostatic regime where famine, malnutrition and epidemic disease acted to regulate the balance between resources and population size. This provides an ideal historic population for an investigation of the direct and indirect effects of malnutrition. Throughout the period studied, a short wavelength oscillation in grain prices was apparently the major external factor that drove exogenous cycles in mortality, birth rate, and migration. In particular, the different responses of children to variations in food supply are emphasised; fluctuations in poor nutrition correlated significantly with the variations in mortality rates for infants (probably indirectly during pregnancy and directly during the first year of life) and for young children (via susceptibility to lethal infectious diseases). Migratory movements contributed to the maintenance of homeostasis in the population dynamics. A medium wavelength cycle in low winter temperatures was associated with a rise in adult mortality which, in turn, promoted an influx of migrants into this saturated habitat. A model incorporating these interacting associations between vital events and exogenous cycles is presented: grain prices were an important density-dependent factor and constituted the major component of the negative feedback of this population and drove the exogenous, short wavelength mortality cycles. Cycles of births and immigration provide a positive feedback for the build-up of susceptibles and the initiation of smallpox epidemics and increased population size.

International Migration in Russia: Dynamics, Policies, Forecast

2011 ◽  
pp. 35-53
Author(s):  
S. Ivanov
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
International Migration ◽  
Low Fertility ◽  
Population Projections ◽  
Future Trends ◽  
Net Migration ◽  
Fertility Trend ◽  
And Migration

Large flows of migrants into low fertility countries increase the weight of international migration in the population dynamics. The current net migration inflow to Russia is about 350 thousand people per year. Migration hypotheses of the population projections include the assumption of constancy of this level until 2050; net migration of 50 thousand people per year; zero net migration and net migration at the level of 900 thousand people per year. Migration hypotheses are combined with the hypotheses of future trends in fertility, including the low, the middle and the high variants. With low fertility and zero net migration the population by 2050 will be reduced by almost half. Stable migration combined with low fertility will not prevent depopulation of the order of almost 1/3 by 2050. If fertility trend follows the high path and migration remains constant the population size will be restored in 10 years and then will increase by 10 per cent. Тo restore the population size by 2020 with slowly increasing fertility, approximately 1, 5 million people more should immigrate into Russia every year than emigrate from it.

scholarly journals Population cycles and outbreaks of small rodents: ten essential questions we still need to solve

Oecologia ◽  
2020 ◽  
Author(s):  
Harry P. Andreassen ◽  
Janne Sundell ◽  
Fraucke Ecke ◽  
Stefan Halle ◽  
Marko Haapakoski ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Large Amplitude ◽  
Driving Forces ◽  
Population Cycles ◽  
Small Rodent ◽  
Small Rodents ◽  
Rodent Population ◽  
The World ◽  
Essential Questions ◽  
Rodent Populations

AbstractMost small rodent populations in the world have fascinating population dynamics. In the northern hemisphere, voles and lemmings tend to show population cycles with regular fluctuations in numbers. In the southern hemisphere, small rodents tend to have large amplitude outbreaks with less regular intervals. In the light of vast research and debate over almost a century, we here discuss the driving forces of these different rodent population dynamics. We highlight ten questions directly related to the various characteristics of relevant populations and ecosystems that still need to be answered. This overview is not intended as a complete list of questions but rather focuses on the most important issues that are essential for understanding the generality of small rodent population dynamics.

scholarly journals A Three-Pronged Approach to Studying Sublethal Insecticide Doses: Characterising Mosquito Fitness, Mosquito Biting Behaviour, and Human/Environmental Health Risks

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 546
Author(s):  
Mara Moreno-Gómez ◽  
Rubén Bueno-Marí ◽  
Miguel. A. Miranda
Keyword(s):  
Environmental Health ◽  
Population Size ◽  
Mosquito Species ◽  
Management Strategies ◽  
Adult Mortality ◽  
Negative Control ◽  
Environmental Health Risks ◽  
Vector Management ◽  
Sublethal Doses ◽  
Biting Behaviour

Worldwide, pyrethroids are one of the most widely used insecticide classes. In addition to serving as personal protection products, they are also a key line of defence in integrated vector management programmes. Many studies have assessed the effects of sublethal pyrethroid doses on mosquito fitness and behaviour. However, much remains unknown about the biological, physiological, demographic, and behavioural effects on individual mosquitoes or mosquito populations when exposure occurs via spatial treatments. Here, females and males of two laboratory-reared mosquito species, Culex pipiens and Aedes albopictus, were exposed to five different treatments: three doses of the pyrethroid prallethrin, as well as an untreated and a negative control. The effects of each treatment on mosquito species, sex, adult mortality, fertility, F1 population size, and biting behaviour were also evaluated. To compare knockdown and mortality among treatments, Mantel–Cox log-rank tests were used. The results showed that sublethal doses reduced mosquito survival, influencing population size in the next generation. They also provided 100% protection to human hosts and presented relatively low risks to human and environmental health. These findings emphasise the need for additional studies that assess the benefits of using sublethal doses as part of mosquito management strategies.

scholarly journals Population dynamics in northwestern China

2021 ◽  
Author(s):  
Xueyan Yang ◽  
Wanxin Li ◽  
Wen Jing ◽  
Chezhuo Gao ◽  
Rui Li ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Population Size ◽  
Ethnic Groups ◽  
Northwestern China ◽  
Average Level ◽  
Han Population ◽  
Sex Structure ◽  
Biological Sex

AbstractThis article analyzes the population dynamics in northwestern China from roughly 2010 to 2020. The area’s dynamics showed a slow, stable increase in population size, a stable increase in the population of non-Han ethnic groups, which increased at a more rapidly than the Han population, and population rejuvenation coupled with a population structure that aged. The biological sex structure fluctuated within a balanced range in northwestern China. Urbanization advanced in northwestern China, throughout this period, but the area’s level of urbanization is still significantly lower than the average level of urbanization nationally.

Population dynamics of priority geostrategic Territories of Russia in 2010-2018

2021 ◽  
Vol 12 (2) ◽  
pp. 123-142
Author(s):  
Valery V. Patsiorkovsky ◽  
Yury A. Simagin ◽  
Djamila J. Murtuzalieva
Keyword(s):  
Economic Development ◽  
Population Dynamics ◽  
Russian Federation ◽  
Far East ◽  
The Arctic ◽  
Natural Growth ◽  
North Caucasus ◽  
Socio Economic Development ◽  
The Russian Federation ◽  
And Migration

The article presents an analysis of the dynamics of the population of the priority geostrategic territories of the Russian Federation. They are highlighted in the "Strategy for the Spatial Development of the Russian Federation until 2025" as territories that are of particular importance for the development of the country as a whole and are distinguished at the same time by special life conditions and the functioning of the economy due to their geographical location. Population dynamics for such territories is both a factor determining socio-economic development and an indicator of the effectiveness of this development. The components of the population dynamics - natural growth and migration flows - are of particular importance. The article describes all four groups of priority geostrategic territories of Russia - isolated from the main territory of the country (exclaves), located in the North Caucasus and the Far East, in the Arctic zone of the Russian Federation. For each group, trends in population dynamics have been identified since the 2010 census, taking into account the components of natural growth and migration. The multidirectional aspect of the main demographic processes in the priority geostrategic territories of the country is revealed - natural growth is combined with the migration outflow of the population, and the migration inflow - with natural decline. At the same time, in the exclave and North Caucasian territories, the population is growing, and in the Far Eastern and Arctic territories it is decreasing. The features of both groups of priority geostrategic territories in comparison with Russia as a whole and of individual constituent entities of the Russian Federation and municipalities within groups of territories are shown. The latter became possible due to the use of the database "Municipal Russia", that summarises demographic statistics for all urban districts and municipal areas of the country, including those located in priority geostrategic territories. As a result of the analysis of the population dynamics, directions have been identified that can lead to an improvement in the demographic situation in the priority geostrategic territories of the country, and, accordingly, will contribute to the socio-economic development of not only these territories, but the entire Russian Federation

Estimating Effective Population Size and Migration Rates From Genetic Samples Over Space and Time

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 429-446 ◽  
Author(s):  
Jinliang Wang ◽  
Michael C Whitlock
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Joint Estimation ◽  
Large Sample Size ◽  
Effective Population ◽  
Likelihood Methods ◽  
Marker Allele ◽  
Migration Rates ◽  
Space And Time ◽  
And Migration

Abstract In the past, moment and likelihood methods have been developed to estimate the effective population size (Ne) on the basis of the observed changes of marker allele frequencies over time, and these have been applied to a large variety of species and populations. Such methods invariably make the critical assumption of a single isolated population receiving no immigrants over the study interval. For most populations in the real world, however, migration is not negligible and can substantially bias estimates of Ne if it is not accounted for. Here we extend previous moment and maximum-likelihood methods to allow the joint estimation of Ne and migration rate (m) using genetic samples over space and time. It is shown that, compared to genetic drift acting alone, migration results in changes in allele frequency that are greater in the short term and smaller in the long term, leading to under- and overestimation of Ne, respectively, if it is ignored. Extensive simulations are run to evaluate the newly developed moment and likelihood methods, which yield generally satisfactory estimates of both Ne and m for populations with widely different effective sizes and migration rates and patterns, given a reasonably large sample size and number of markers.

scholarly journals The influence of microhabitat on the population dynamics of four herbaceous species in a semiarid area of northeastern Brazil

2016 ◽  
Vol 76 (1) ◽  
pp. 45-54 ◽  
Author(s):  
K. A. Silva ◽  
J. M. F. F. Santos ◽  
J. R. Andrade ◽  
E. N. Lima ◽  
U. P. Albuquerque ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Mortality Rates ◽  
Dry Forest ◽  
Northeastern Brazil ◽  
Annual Rainfall ◽  
Herbaceous Species ◽  
Forest Fragment ◽  
Experimental Station ◽  
Over Time

Abstract Variation in annual rainfall is considered the most important factor influencing population dynamics in dry environments. However, different factors may control population dynamics in different microhabitats. This study recognizes that microhabitat variation may attenuate the influence of climatic seasonality on the population dynamics of herbaceous species in dry forest (Caatinga) areas of Brazil. We evaluated the influence of three microhabitats (flat, rocky and riparian) on the population dynamics of four herbaceous species (Delilia biflora, Commelina obliqua, Phaseolus peduncularis and Euphorbia heterophylla) in a Caatinga (dry forest) fragment at the Experimental Station of the Agronomic Research Institute of Pernambuco in Brazil, over a period of three years. D. biflora, C. obliqua and P. peduncularis were found in all microhabitats, but they were present at low densities in the riparian microhabitat. There was no record of E. heterophylla in the riparian microhabitat. Population size, mortality rates and natality rates varied over time in each microhabitat. This study indicates that different establishment conditions influenced the population size and occurrence of the four species, and it confirms that microhabitat can attenuate the effect of drought stress on mortality during the dry season, but the strength of this attenuator role may vary with time and species.

scholarly journals How host phenology impacts multi-season epidemic cycles

2021 ◽  
Author(s):  
Hannelore MacDonald ◽  
Dustin Brisson
Keyword(s):  
Mathematical Model ◽  
Population Dynamics ◽  
Population Cycles ◽  
Seasonal Activity ◽  
Host Interactions ◽  
Host Phenology ◽  
Demographic Impact ◽  
Host Parasite ◽  
Parasite Populations ◽  
Parasite Dynamics

Parasite-host interactions can result in periodic population dynamics when parasites over-exploit host populations. The timing of host seasonal activity, or host phenology, determines the frequency and demographic impact of parasite-host interactions which may govern if the parasite can sufficiently over-exploit their hosts to drive population cycles. We describe a mathematical model of a monocyclic, obligate-killer parasite system with seasonal host activity to investigate the consequences of host phenology on host-parasite dynamics. The results suggest that parasites can reach the densities necessary to destabilize host dynamics and drive cycling in only some phenological scenarios, such as environments with short seasons and synchronous host emergence. Further, only parasite lineages that are sufficiently adapted to phenological scenarios with short seasons and synchronous host emergence can achieve the densities necessary to over-exploit hosts and produce population cycles. Host-parasite cycles can also generate an eco-evolutionary feedback that slows parasite adaptation to the phenological environment as rare advantageous phenotypes are driven to extinction when introduced in phases of the cycle where host populations are small and parasite populations are large. The results demonstrate that seasonal environments can drive population cycling in a restricted set of phenological patterns and provides further evidence that the rate of adaptive evolution depends on underlying ecological dynamics.

POPULATION DYNAMICS OF SEX-DETERMINING ALLELES IN HONEY BEES AND SELF-INCOMPATIBILITY ALLELES IN PLANTS

Genetics ◽  
1979 ◽  
Vol 91 (3) ◽  
pp. 609-626 ◽  
Author(s):  
Shozo Yokoyama ◽  
Masatoshi Nei
Keyword(s):  
Population Dynamics ◽  
Population Size ◽  
Honey Bee ◽  
Honey Bees ◽  
Finite Population ◽  
Large Population ◽  
Allele Frequencies ◽  
Self Incompatibility ◽  
Overdominant Selection ◽  
Incompatibility Alleles

ABSTRACT Mathematical theories of the population dynamics of sex-determining alleles in honey bees are developed. It is shown that in an infinitely large population the equilibrium frequency of a sex allele is l/n, where n is the number of alleles in the population, and the asymptotic rate of approach to this equilibrium is 2/(3n) per generation. Formulae for the distribution of allele frequencies and the effective and actual numbers of alleles that can be maintained in a finite population are derived by taking into account the population size and mutation rate. It is shown that the allele frequencies in a finite population may deviate considerably from l/n. Using these results, available data on the number of sex alleles in honey bee populations are discussed. It is also shown that the number of self-incompatibility alleles in plants can be studied in a much simpler way by the method used in this paper. A brief discussion about general overdominant selection is presented.

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