Estimating the Rate of Adaptive Molecular Evolution in the Presence of Slightly Deleterious Mutations and Population Size Change

The aim of this study is to discuss changes in thepopulation and indicate the main reasons of these changes inrural areas of West Pomeranian voivodeship. The study wasconducted on the local level and based on Central StatisticalOffice data from the years 2010 to 2014. In the first part ofthe research, main demographic information is discussed. Itincludes population density, natural increase per 1000 populationand net migration per 1000 population in rural areasof West Pomeranian voivodeship. In the next part of the research,the average population growth rate was counted in theyears 2011–2014. Based on these changes, researched unitswere divided into four groups – two groups with positivechanges and two groups with negative changes. Subsequently,the main reasons of the changes in population size were analyzedin particular groups including natural increase, migration,population structure by age, level of unemployment andentrepreneurship. All indicators were designated as averagesfrom 2011 to 2014. According to the results in most of the researchunits, the net migration determined the population size.The net migration was characterized by higher absolute valuesthan natural increase. The population size changes are relatedto density. The lowest density areas are more depopulated.Moreover, the population size changes are positive related tothe level of entrepreneurship and negative related to the levelof unemployment.

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The effect of background selection against deleterious mutations on weakly selected, linked variants

Genetics Research ◽

10.1017/s0016672300032365 ◽

1994 ◽

Vol 63 (3) ◽

pp. 213-227 ◽

Cited By ~ 220

Author(s):

Brian Charlesworth

Keyword(s):

Genetic Diversity ◽

Molecular Evolution ◽

Effective Size ◽

Background Selection ◽

Deleterious Mutations ◽

Deleterious Alleles ◽

Rates Of Evolution ◽

Selection Approach ◽

Slightly Deleterious Mutations ◽

Neutral Case

SummaryThis paper analyses the effects of selection against deleterious alleles maintained by mutation (‘ background selection’) on rates of evolution and levels of genetic diversity at weakly selected, completely linked, loci. General formulae are derived for the expected rates of gene substitution and genetic diversity, relative to the neutral case, as a function of selection and dominance coefficients at the loci in question, and of the frequency of gametes that are free of deleterious mutations with respect to the loci responsible for background selection. As in the neutral case, most effects of background selection can be predicted by considering the effective size of the population to be multiplied by the frequency of mutation-free gametes. Levels of genetic diversity can be sharply reduced by background selection, with the result that values for sites under selection approach those for neutral variants subject to the same regime of background selection. Rates of fixation of slightly deleterious mutations are increased by background selection, and rates of fixation of advantageous mutations are reduced. The properties of sex-linked and autosomal asexual and self-fertilizing populations are considered. The implications of these results for the interpretation of studies of molecular evolution and variation are discussed.

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