HISTORICAL POPULATION SIZE CHANGE OF BOWHEAD WHALES INFERRED FROM DNA SEQUENCE POLYMORPHISM DATA

Drosophila ananassae is a cosmopolitan species with a geographic range throughout most of the tropical and subtropical regions of the world. Previous studies of DNA sequence polymorphism in three genes has shown evidence of selection affecting broad expanses of the genome in regions with low rates of recombination in geographically local populations in and around India. The studies suggest that extensive physical and genetic maps based on molecular markers, and detailed studies of population structure may provide insight into the degree to which natural selection affects DNA sequence polymorphism across broad regions of chromosomes. We have isolated 85 dinucleotide repeat microsatellite sequences and developed assay conditions for genotyping using PCR. The dinucleotide repeats we isolated are shorter, on average, than those isolated in many other Drosophila species. Levels of genetic variation are high, comparable to Drosophila melanogaster. The levels of variation indicate the effective population size of an Indonesian population of D. ananassae is 58692 (infinite allele model) and 217284 (stepwise mutation model), similar to estimates of effective population size for D. melanogaster calculated using dinucleotide repeat microsatellites. The data also show that the Indonesian population is in a rapid expansion phase. Cross-species amplification of the microsatellites in 11 species from the Ananassae, Elegans, Eugracilis and Ficusphila subgroups indicates that the loci may be useful for studies of the sister species, D. pallidosa, but will have limited use for more distantly related species.

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DNA Polymorphism in Lycopersicon and Crossing-Over per Physical Length

Genetics ◽

10.1093/genetics/150.4.1585 ◽

1998 ◽

Vol 150 (4) ◽

pp. 1585-1593 ◽

Cited By ~ 21

Author(s):

Wolfgang Stephan ◽

Charles H Langley

Keyword(s):

Dna Sequence ◽

Dna Polymorphism ◽

Sequence Polymorphism ◽

Breeding Systems ◽

Crossing Over ◽

Physical Length ◽

Interspecific Divergence ◽

Dna Sequence Polymorphism ◽

Outcrossing Species ◽

Genomic Regions

Abstract Surveys in Drosophila have consistently found reduced levels of DNA sequence polymorphism in genomic regions experiencing low crossing-over per physical length, while these same regions exhibit normal amounts of interspecific divergence. Here we show that for 36 loci across the genomes of eight Lycopersicon species, naturally occurring DNA polymorphism (scaled by locus-specific divergence between species) is positively correlated with the density of crossing-over per physical length. Large between-species differences in the amount of DNA sequence polymorphism reflect breeding systems: selfing species show much less within-species polymorphism than outcrossing species. The strongest association of expected heterozygosity with crossing-over is found in species with intermediate levels of average nucleotide diversity. All of these observations appear to be in qualitative agreement with the hitchhiking effects caused by the fixation of advantageous mutations and/or “background selection” against deleterious mutations.

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DNA Sequence Variation and the Recombinational Landscape in Drosophila pseudoobscura: A Study of the Second Chromosome

Genetics ◽

10.1093/genetics/153.2.859 ◽

1999 ◽

Vol 153 (2) ◽

pp. 859-869 ◽

Cited By ~ 7

Author(s):

Martha T Hamblin ◽

Charles F Aquadro

Keyword(s):

Population Size ◽

Effective Population Size ◽

Dna Sequence ◽

Sequence Variation ◽

Population Expansion ◽

Drosophila Pseudoobscura ◽

Effective Population ◽

Standing Variation ◽

Dna Sequence Polymorphism ◽

Slightly Deleterious Mutations

Abstract The relationship between rates of recombination and DNA sequence polymorphism was analyzed for the second chromosome of Drosophila pseudoobscura. We constructed integrated genetic and physical maps of this chromosome using molecular markers at 10 loci spanning most of its physical length. The total length of the map was 128.2 cM, almost twice that of the homologous chromosome arm (3R) in D. melanogaster. There appears to be very little centromeric suppression of recombination, and rates of recombination are quite uniform across most of the chromosome. Levels of sequence variation (θW, based on the number of segregating sites) at seven loci (tropomyosin 1, Rhodopsin 3, Rhodopsin 1, bicoid, Xanthine dehydrogenase, Myosin light chain 1, and ribosomal protein 49) varied from 0.0036 to 0.0167. Generally consistent with earlier studies, the average estimate of θW at total sites is 1.5-fold higher than that in D. melanogaster, while average θW at silent sites is almost 3-fold higher. These estimates of variation were analyzed in the context of a background selection model under the same parameters of mutation rate and selection as have been proposed for D. melanogaster. It is likely that a significant fraction of the higher level of sequence variation in D. pseudoobscura can be explained by differences in regional rates of recombination rather than a larger species-level effective population size. However, the distribution of variation among synonymous, nonsynonymous, and noncoding sites appears to be quite different between the species, making direct comparisons of neutral variation, and hence inferences about effective population size, difficult. Tajima’s D statistics for 6 out of the 7 loci surveyed are negative, suggesting that D. pseudoobscura may have experienced a rapid population expansion in the recent past or, alternatively, that slightly deleterious mutations constitute an important component of standing variation in this species.

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Genetic diversity and matrilineal genetic signature of native Ethiopian donkeys (Equus asinus) inferred from mitochondrial DNA sequence polymorphism

Livestock Science ◽

10.1016/j.livsci.2014.06.006 ◽

2014 ◽

Vol 167 ◽

pp. 73-79 ◽

Cited By ~ 8

Author(s):

E. Kefena ◽

T. Dessie ◽

A. Tegegne ◽

A. Beja-Pereira ◽

M. Yusuf Kurtu ◽

...

Keyword(s):

Genetic Diversity ◽

Mitochondrial Dna ◽

Dna Sequence ◽

Sequence Polymorphism ◽

Mitochondrial Dna Sequence ◽

Genetic Signature ◽

Equus Asinus ◽

Dna Sequence Polymorphism

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POPULATION SIZE CHANGE IN RURAL AREAS OF WEST POMERANIAN VOIVODESHIP IN 2011–2014

Journal of Agribusiness and Rural Development ◽

10.17306/j.jard.2018.00393 ◽

2018 ◽

Vol 47 (1) ◽

pp. 65-72

Author(s):

Luiza Ossowska ◽

Natalia Bartkowiak-Bakun

Keyword(s):

Growth Rate ◽

Population Size ◽

Rural Areas ◽

Population Growth Rate ◽

Local Level ◽

Natural Increase ◽

Demographic Information ◽

Size Change ◽

Net Migration ◽

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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