The intrinsic dynamics of population density

1995 ◽  
pp. 135-168 ◽  
Keyword(s):  
Population Density ◽  
Dynamics Of Population

scholarly journals THE DYNAMICS OF THE NUMBER OF ORIBATIC MITES ON THE PASTURES OF THE IVANOVO REGION AND THEIR INVASIBILITY OF THE MONISTIA CISTICERCOIDES

2019 ◽  
pp. 221-225 ◽  
Author(s):  
Zhdanova ◽  
Kryuchkova
Keyword(s):  
Population Density ◽  
Preventive Measures ◽  
Soil Surface ◽  
Weather Conditions ◽  
Oribatid Mites ◽  
Different Types ◽  
Dynamics Of Population ◽  
June July ◽  
High Degree ◽  
Natural Grassland

The distribution of mites on the soil surface of different types of pastures, the invasion of oribatids by monies larvae are dependent on climatic and weather conditions of the area, as well as the degree of infection with monies of the grazed livestock of ruminants. Seasonal dynamics of population density of oribatid ticks on natural and artificial pastures of two livestock farms of the Ivanovo region is studied. In soil and grass samples 5 species of shell mites were identified: Scheloribates laevigatus, Scheloribates latipes, Punctoribates punctum, Punctoribates sellnicki and Ceratozetes mediocris, cysticercoid-infested monies. Dominant species were representatives of the genus Scheloribates (65,8%), subdominant – genus Punctoribates (26,7%). The population density of oribatid mites on natural grassland pastures in may averaged 198±17,8 specimens per 1 m2 with cysticercoid monies equal to 3,39%. In June-July, the number of oribatids ranged from 249±23,5 – 298±31,2 specimens on 1 m2 at EI = 4,47–6,9% respectively. The greatest number of oribatids was found in August-September: 343±39,4 – 368±42,4 specimens per 1 m2 at EI = 8,7–9,2%. In October the population density of oribatid mites decreased to 201±28,4 individuals per 1 m2 at EI = 4,54%. Artificial (cultural) pastures, the number of oribatid mites does not exceed 108±9,3 individuals per 1 m2. The contamination of the oribatids with cysticercoids of moniesia on these pastures has not been found. The research results make it possible to assume a high degree of invasion of ruminants by moniesia when grazing them on natural meadow pastures and plan preventive measures.

scholarly journals Inferring recent demography from isolation by distance of long shared sequence blocks

2016 ◽  
Author(s):  
Harald Ringbauer ◽  
Graham Coop ◽  
Nick Barton
Keyword(s):  
Population Density ◽  
Diffusion Approximation ◽  
Isolation By Distance ◽  
Composite Likelihood ◽  
Effective Density ◽  
Data Set ◽  
Dynamics Of Population ◽  
Estimation Scheme ◽  
Analytical Formulas ◽  
Sharing Patterns

ABSTRACTRecently it has become feasible to detect long blocks of almost identical sequence shared between pairs of genomes. These so called IBD-blocks are direct traces of recent coalescence events, and as such contain ample signal for inferring recent demography. Here, we examine sharing of such blocks in two-dimensional populations with local migration. Using a diffusion approximation to trace genetic ancestry back in time, we derive analytical formulas for patterns of isolation by distance of long IBD-blocks, which can also incorporate recent population density changes. As a main result, we introduce an inference scheme that uses a composite likelihood approach to fit observed block sharing to these formulas. We assess our inference method on simulated block sharing data under several standard population genetics models. We first validate the diffusion approximation by showing that the theoretical results closely match simulated block sharing patterns. We then show that our inference scheme rather accurately and robustly recovers estimates of the dispersal rate and effective density, as well as bounds on recent dynamics of population density. To demonstrate an application, we use our estimation scheme to explore the fit of a diffusion model to Eastern European samples in the POPRES data set. We show that ancestry diffusing with a rate of during the last centuries, combined with accelerating population growth, can explain the observed exponential decay of block sharing with pairwise sample distance.

Dynamics of Population and Family Welfare 1989

1991 ◽  
Vol 45 (3) ◽  
pp. 552-553
Author(s):  
Nigel R. Crook
Keyword(s):  
Family Welfare ◽  
Dynamics Of Population

Convergence of regional population density in Russia over 120 years

2020 ◽  
pp. 133-158
Author(s):  
K. A. Kholodilin ◽  
Y. I. Yanzhimaeva
Keyword(s):  
Population Density ◽  
Spatial Dependence ◽  
Population Distribution ◽  
Regional Level ◽  
Capital City ◽  
County Level ◽  
Spatial Effects ◽  
Russian Regions ◽  
Regional Population ◽  
Regional Population Density

A relative uniformity of population distribution on the territory of the country is of importance from socio-economic and strategic perspectives. It is especially important in the case of Russia with its densely populated West and underpopulated East. This paper considers changes in population density in Russian regions, which occurred between 1897 and 2017. It explores whether there was convergence in population density and what factors influenced it. For this purpose, it uses the data both at county and regional levels, which are brought to common borders for comparability purposes. Further, the models of unconditional and conditional β-convergence are estimated, taking into account the spatial dependence. The paper concludes that the population density equalization took place in 1897-2017 at the county level and in 1926—1970 at the regional level. In addition, the population density increase is shown to be influenced not only by spatial effects, but also by political and geographical factors such as climate, number of GULAG camps, and the distance from the capital city.

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