scholarly journals SAMPLING VARIANCES OF HETEROZYGOSITY AND GENETIC DISTANCE

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 379-390
Author(s):  
Masatoshi Nei ◽  
A K Roychoudhury

ABSTRACT Mathematical formulae for the sampling variances of average heterozygosity and Nei's genetic distance are developed. These sampling variances are decomposed into their two components, i.e. the inter-locus and intra-locus variances. The relationship between the number of loci and the number of individuals per locus to be examined for estimating average heterozygosity and genetic distance is also discussed. The utility of the inter-locus variance of heterozygosity for studying the mechanism of maintenance of genetic variability in populations is indicated.

1993 ◽  
Vol 71 (4) ◽  
pp. 586-591 ◽  
Author(s):  
R. E. Vaillancourt ◽  
N. F. Weeden

The cowpea (Vigna unguiculata (L.) Walp.) is an important crop of tropical Africa, Asia, and South America. However, the relationship between the cowpea and other species of subg. Vigna is relatively unknown. The objective of this study was to assess the genetic distance among species of subg. Vigna using isozymes. Twenty-four populations of the cowpea species and 39 populations from 10 other species (at least one species per section of subgenus Vigna) were sampled. Nei's genetic distance was calculated from allelic frequencies at 26 isozyme loci. UPGMA cluster analysis was performed. The range of genetic distance among species of subg. Vigna (0.41 – 2.69) was greater than previously reported in most plant genera. Three clusters of species were apparent. The first cluster included three species of sect. Vigna (V. luteola, V. oblongifolia, and V. subterranea (the Bambara groundnut)). The second cluster grouped together sections Liebrechtsia and Macrodontae. The third cluster included V. unguiculata, V. reticulata, and V. vexillata. The distances between species of this cluster were large and of similar size in all combinations (range from 0.92 to 0.95). None of the species included in this survey can be called a close relative of V. unguiculata. Key words: Vigna, cowpea, isozymes, genetic distances.


Genetics ◽  
1978 ◽  
Vol 89 (3) ◽  
pp. 583-590 ◽  
Author(s):  
Masatoshi Nei

ABSTRACT The magnitudes of the systematic biases involved in sample heterozygosity and sample genetic distances are evaluated, and formulae for obtaining unbiased estimates of average heterozygosity and genetic distance are developed. It is also shown that the number of individuals to be used for estimating average heterozygosity can be very small if a large number of loci are studied and the average heterozygosity is low. The number of individuals to be used for estimating genetic distance can also be very small if the genetic distance is large and the average heterozygosity of the two species compared is low.


2003 ◽  
Vol 32 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Marco Antonio Machado ◽  
Ivan Schuster ◽  
Mário Luiz Martinez ◽  
Ana Lúcia Campos

Four cattle breeds (Gyr, Nellore, Guzerat and Holstein) were analyzed by amplification of genomic DNA using microsatellite loci to evaluate the genetic diversity within and among them. DNA samples of 18 animals from each breed were collected to access the genetic content of them. Allele frequencies were calculated and used to generate a Nei's genetic distance matrix what was used to build a dendrogram following UPGMA clustering. As expected, Holstein breed was the most distinct from the other breeds: 1.15 in relation to Gyr, 1.12 in relation to Nellore and 0.94 in relation to Guzerat. The closest genetic distance was 0.25 between Guzerat and Nellore. A total of 64 alleles in all four breeds were detected using nine microsatellite primers. Each breed showed 53% of the total number of alleles. The average number of alleles per locus was 7.11 ± 3.21. The most informative locus was BMS1237 with 53% of observed heterozygosity and the least informative locus was BMS3004 with 12% only. The average heterozygosity detected for the nine loci were 35% and the expected value for Hardy-Weinberg equilibrium was 53%. This low heterozygosity suggests a high endogamy level among the animals sampled within each breed.


Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 361-367 ◽  
Author(s):  
Wolfgang Spielmeyer ◽  
Odile Moullet ◽  
André Laroche ◽  
Evans S Lagudah

Abstract A detailed RFLP map was constructed of the distal end of the short arm of chromosome 1D of Aegilops tauschii, the diploid D-genome donor species of hexaploid wheat. Ae. tauschii was used to overcome some of the limitations commonly associated with molecular studies of wheat such as low levels of DNA polymorphism. Detection of multiple loci by most RFLP probes suggests that gene duplication events have occurred throughout this chromosomal region. Large DNA fragments isolated from a BAC library of Ae. tauschii were used to determine the relationship between physical and genetic distance at seed storage protein loci located at the distal end of chromosome 1DS. Highly recombinogenic regions were identified where the ratio of physical to genetic distance was estimated to be <20 kb/cM. These results are discussed in relation to the genome-wide estimate of the relationship between physical and genetic distance.


Zootaxa ◽  
2021 ◽  
Vol 4926 (3) ◽  
pp. 401-416
Author(s):  
MOHAMMAD HUSSAIN FALAHZADAH ◽  
EBRAHIM SHOKOOHI ◽  
GHOLAM HOSSEIN MORAVEJ ◽  
PHATU WILLIAM MASHELA ◽  
ABDUL KHALID MADADI ◽  
...  

Several soil samples from different habitats in Badakhshan province of Afghanistan were collected to isolate and characterize bacteria feeding nematodes. The Galleria mellonella-baiting method was used for the isolation of the Afghan insect-associated nematodes. The nematodes were studied using morphological and morphometric data. The Oscheius specimen was characterized by a longer body (630–820 µm) and shorter pharynx (125–145 µm), whereas other morphological characters were not unusual. The Diploscapter specimen had an annulated cuticle, with lip region width 1.5 times shorter than the stoma, and had separated pharyngeal corpus from the isthmus and vulva located in the middle of the body. The molecular data were derived using three loci; 18S, 28S (D2/D3 segment), and ITS rRNA region, which were utilized to measure the genetic distance. The phylogenetic analysis was conducted to reconstruct the relationship tree. Both morphological and molecular approaches confirmed the identity of nematode isolates as Oscheius tipulae and Diploscapter coronatus. This is the first report of insect-associated nematodes from the soil of Afghanistan. Both species were capable of infecting and killing G. mellonella larvae in less than 96 h. 


1989 ◽  
Vol 84 (4) ◽  
pp. 535-543 ◽  
Author(s):  
Maria Goreti Rosa-Freitas

Anopheles (Nyssorhynchus) deaneorum sp. n. is described from specimens collected in Guajará-Mirim, Rondônia state and Rio Branco, Acre state, Brazil, on human and animal baits, inside dwellings and from the progenies of engorged females. A detailed description of the shape of egg, external appearance of adult female and male, genitalias, female cibarial armature and complete chaetotaxy of pupa and larva show that it can be distinguished from Anopheles albitarsis from the type-locality and other areas by the paler general external appearance of the adult, the posterolateral tufts of scales, on the female abdominal terga and the branching of the outer anterior clypeal seta (3-C) of the fourth instar larva (as shown in illustrations). If species can also be distinguished from An. albitarsis from the type locality by the allele frequencies at 11 enzymic loci as represented by Nei's Genetic Distance.


2003 ◽  
Vol 33 (1) ◽  
pp. 137-142 ◽  
Author(s):  
Myriam Elizabeth Vinocur ◽  
Karin Erica Brass ◽  
Mara Iolanda Batistella Rubin ◽  
Carlos Antonio Mondino Silva

Allelic frequencies of 7 blood groups and 8 protein systems were determined in 6 herds of Criollo horse breed raised in Rio Grande do Sul, Brazil. Analysis of these frequencies showed a significant isolation component (Fst = 0.0866; p<0.01) and construction of dendogram using Nei´s D confirmed this difference among the 6 herds. The highest values measuring genetic variability on 15 blood types were average heterozygosity: 0.4631; total number of alleles: 87 and probability of exclusion: 98%. When all herds were considered together, the inbreeding level (Fis) was zero. These results indicate that the Criollo horses have a large genetic variability.


2014 ◽  
Vol 7 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Jan Boehmer ◽  
Stephen Lacy

This study analyzes how interactivity on Facebook relates to users’ browsing behaviors such as clicking a link, visiting a Web site, clicking articles on a Web site, and spending time on a sports news Web site. Regression analyses of 502 Facebook posts and the corresponding news articles show that the number of individuals who clicked on a link is not related to higher levels of interactivity, but an increase in interactivity did affect the number of overall visits generated. In addition, higher levels of interactivity had a slight negative correlation with the number of pages visited and the time spent on an organization’s Web site. Implications for the training and work routines of sport communication professionals in organizations, journalism, and public relations are discussed.


Sign in / Sign up

Export Citation Format

Share Document