scholarly journals Predicting the Population Growth and Structure of China Based on Grey Fractional-Order Models

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaojun Guo ◽  
Rui Zhang ◽  
Naiming Xie ◽  
Jingliang Jin
Keyword(s):  
Population Size ◽  
Fractional Order ◽  
Population Change ◽  
External Disturbance ◽  
Aging Population ◽  
Data Series ◽  
Grey System ◽  
Effective Population ◽  
Population System ◽  
Population Prediction

Scientific prediction and accurate grasp of the future trend of population change are conducive to the formulation of different population policies at different stages, so as to alleviate the adverse effects of the aging population on society and provide scientific theoretical reference for controlling the population size and making policy. Considering that the population system is affected by many complex factors and the structural relationship among these factors is complex, it can be regarded as a typical dynamic grey system. In this paper, the fractional-order GM (1, 1) model and the fractional-order Verhulst model are established, respectively, based on the statistical data of China's population indices from 2015 to 2019 to forecast the population size and the change trend of population structure of China from 2015 to 2050 in the short-term and medium- to long-term. The forecast results show that China’s population will grow in an inverse S shape from 2015 to 2050, when the total population will reach 1.43 billion. Moreover, during this period, the birth rate and natural growth rate of population will decrease year by year, and the proportion of aging population and the dependency ratio of population will increase year by year. Besides, the problem of aging population is going to become increasingly serious. The application of grey system method to population prediction can mine the complex information contained in the population number series. Meanwhile, the fractional-order accumulation can weaken the randomness of the original data series and reduce the influence of external disturbance factors, so it is a simple and effective population prediction method.

scholarly journals Conservation of genetic variation in harvested salmon populations

2004 ◽  
Vol 61 (8) ◽  
pp. 1389-1397 ◽  
Author(s):  
Kjetil Hindar ◽  
Jarle Tufto ◽  
Leif Magnus Sættem ◽  
Torveig Balstad
Keyword(s):  
Genetic Variation ◽  
Population Size ◽  
Effective Population Size ◽  
Effective Population ◽  
Population System ◽  
Fitness Consequences ◽  
Conservation Genetic ◽  
Population Sizes ◽  
And Migration ◽  
Source Sink

Abstract Management of a group of Atlantic salmon (Salmo salar) populations that are harvested together in the ocean, but separately in freshwater, is looked at from a genetic perspective. A model that estimates total effective population size from local effective population sizes and migration patterns is applied to a system of ten salmon populations in the Sognefjorden district, western Norway. This population system is dominated numerically by the River Lærdalselva population, which may act as a source of migrants into nine smaller populations in a “source–sink” metapopulation. The total effective population size of this system is to a large extent dependent on the effective population size of the Lærdalselva population, but the contribution per spawner to the total effective population size is greater for a fish from the smaller populations than for a fish from Lærdalselva. The results are discussed in light of conservation genetic theory, and empirical results on the fitness consequences of loss of genetic variation in salmonids. The genetic consequences of harvesting need to be assessed both at the levels of local populations and the metapopulation.

Evolutionary genetics of small populations

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Evolutionary Genetics ◽  
Small Population ◽  
Small Populations ◽  
Effective Population ◽  
Genetic Management ◽  
Evolutionary Genetic ◽  
Loss Of Genetic Diversity ◽  
Number Of Individuals

Genetic management of fragmented populations involves the application of evolutionary genetic theory and knowledge to alleviate problems due to inbreeding and loss of genetic diversity in small population fragments. Populations evolve through the effects of mutation, natural selection, chance (genetic drift) and gene flow (migration). Large outbreeding, sexually reproducing populations typically contain substantial genetic diversity, while small populations typically contain reduced levels. Genetic impacts of small population size on inbreeding, loss of genetic diversity and population differentiation are determined by the genetically effective population size, which is usually much smaller than the number of individuals.

scholarly journals A phylogenetic estimator of effective population size or mutation rate.

Genetics ◽  
1994 ◽  
Vol 136 (2) ◽  
pp. 685-692 ◽  
Author(s):  
Y X Fu
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Mutation Rate ◽  
Dna Sequences ◽  
High Efficiency ◽  
Minimum Variance ◽  
Population Subdivision ◽  
Effective Population ◽  
Fisher Model ◽  
Mitochondrial Sequences

Abstract A new estimator of the essential parameter theta = 4Ne mu from DNA polymorphism data is developed under the neutral Wright-Fisher model without recombination and population subdivision, where Ne is the effective population size and mu is the mutation rate per locus per generation. The new estimator has a variance only slightly larger than the minimum variance of all possible unbiased estimators of the parameter and is substantially smaller than that of any existing estimator. The high efficiency of the new estimator is achieved by making full use of phylogenetic information in a sample of DNA sequences from a population. An example of estimating theta by the new method is presented using the mitochondrial sequences from an American Indian population.

scholarly journals Harmful mutation load in the mitochondrial genomes of cattle breeds

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Sankar Subramanian
Keyword(s):  
Population Size ◽  
Artificial Selection ◽  
Deleterious Mutation ◽  
Genetic Diseases ◽  
Mitochondrial Genomes ◽  
Deleterious Mutations ◽  
Founder Population ◽  
Mutation Load ◽  
Effective Population ◽  
Cattle Breeds

Abstract Objective Domestication of wild animals results in a reduction in the effective population size, and this could affect the deleterious mutation load of domesticated breeds. Furthermore, artificial selection will also contribute to the accumulation of deleterious mutations due to the increased rate of inbreeding among these animals. The process of domestication, founder population size, and artificial selection differ between cattle breeds, which could lead to a variation in their deleterious mutation loads. We investigated this using mitochondrial genome data from 364 animals belonging to 18 cattle breeds of the world. Results Our analysis revealed more than a fivefold difference in the deleterious mutation load among cattle breeds. We also observed a negative correlation between the breed age and the proportion of deleterious amino acid-changing polymorphisms. This suggests a proportionally higher deleterious SNPs in young breeds compared to older breeds. Our results highlight the magnitude of difference in the deleterious mutations present in the mitochondrial genomes of various breeds. The results of this study could be useful in predicting the rate of incidence of genetic diseases in different breeds.

scholarly journals Alu Evolution in Human Populations: Using the Coalescent to Estimate Effective Population Size

Genetics ◽  
1997 ◽  
Vol 147 (4) ◽  
pp. 1977-1982
Author(s):  
Stephen T Sherry ◽  
Henry C Harpending ◽  
Mark A Batzer ◽  
Mark Stoneking
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Genomic Library ◽  
Diploid Cell ◽  
Human Populations ◽  
Effective Population ◽  
Alu Repeats ◽  
Branch Lengths ◽  
Diploid Cell Line ◽  
Coalescence Theory

Abstract There are estimated to be ~1000 members of the Ya5 Alu subfamily of retroposons in humans. This Subfamily has a distribution restricted to humans, with a few copies in gorillas and chimpanzees. Fifty-seven Ya5 elements were previously cloned from a HeLaderived randomly sheared total genomic library, sequenced, and screened for polymorphism in a panel of 120 unrelated humans. Forty-four of the 57 cloned Alu repeats were monomorphic in the sample and 13 Alu repeats were dimorphic for insertion presence/absence. The observed distribution of sample frequencies of the 13 dimorphic elements is consistent with the theoretical expectation for elements ascertained in a single diploid cell line. Coalescence theory is used to compute expected total pedigree branch lengths for monomorphic and dimorphic elements, leading to an estimate of human effective population size of ~18,000 during the last one to two million years.

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