Genetical Structure of Populations.

S. K. Jain; K. Chapman Mather

doi:10.2307/2407230

Genetical Structure Among Nine Population Groups of Jammu and Kashmir, India

Journal of Human Ecology ◽

10.1080/09709274.1992.11907924 ◽

1992 ◽

Vol 3 (3) ◽

pp. 193-219

Author(s):

M.K. Bhasin ◽

Asha Khanna

Keyword(s):

Jammu And Kashmir ◽

Population Groups ◽

Genetical Structure

Download Full-text

Genetical Structure of Populations, By Kenneth Mather (Birminghan, GB). Chapman and Hall, London 1973. Hard cover with jacket, 13.5 × 21.5 cm, VIII + 197 pp, 25 illustrations, 18 tables. Price: £ 4.00 (approximately US $ 9.00).

Acta geneticae medicae et gemellologiae ◽

10.1017/s1120962300022216 ◽

1975 ◽

Vol 24 (1-2) ◽

pp. 180-180

Keyword(s):

Genetical Structure ◽

Hard Cover

Download Full-text

A further modification in the triple testcross analysis when testers share common loci

Canadian Journal of Genetics and Cytology ◽

10.1139/g85-100 ◽

1985 ◽

Vol 27 (6) ◽

pp. 661-664

Author(s):

Parminder S. Virk ◽

D. S. Virk

Keyword(s):

Breeding Lines ◽

Unbiased Estimates ◽

Genetical Structure

For investigating the genetical structure of a population of homozygous lines, modifications in the triple testcross analysis that allow for the effect of common loci shared by the pure-breeding testers, L1 and L2, have been previously proposed. The unbiased estimates of the additive genetic and dominance components are, however, correlated as they are obtained from statistics that are nonorthogonal. Further modifications are suggested where full triple testcross families L1i (= Pi × L1), L2i (= Pi × L2) and L3i (= Pi × L3; L3 = L1 × L2) along with selfed progenies of L1i (= L1si) and L2i (= L2si) and pure-breeding lines (Pi) themselves are raised. Alternatively, full triple testcross progenies (L1i, L2i, and L3i) can be raised along with the selfs of L3i (= L3si) families and parental (Pi) lines. These combinations of normal and selfed progenies allow one to test and estimate unbiased additive and dominance components, free from the effect of common loci in the testers and from statistics that are statistically orthogonal. The components of variation are, therefore, estimated independently.Key words: triple testcross, inadequate testers, components of variation.

Download Full-text

Genetical structure of populations of modelling species of terrestrial mollusks in conditions of the urbanized landscape on example Сhondrula tridens Müll (Gastropoda, Pulmonata)

Ecological genetics ◽

10.17816/ecogen9254-64 ◽

2011 ◽

Vol 9 (2) ◽

pp. 54-64

Author(s):

Eduard A Snegin

Keyword(s):

Natural Selection ◽

Gel Electrophoresis ◽

Forest Steppe ◽

Gene Pools ◽

Automatic Processes ◽

Effective Number ◽

Historical Factors ◽

Genetical Structure ◽

Electrophoresis Of Proteins ◽

Terrestrial Mollusks

On the basis of the analysis of the morphological and genetical variability revealed by a method of gel-electrophoresis of proteins in PAAG, the state of gene pools of populations of modeling species Сhondrula tridens Müll (threedens snail) in conditions of the urbanized forest-steppe landscape of the south of Mid-Russia Upland is investigated. In the majority of the investigated bunches authentic decrease of a level of heterozygosity and the decrease of an allelic diversification caused, both is fixed by natural historical factors, and factors of an anthropogenic parentage. The genetic-automatic processes in populations are considered and vectors of natural selection are defined. Calculation of effective number of researched bunches is spent.

Download Full-text

Stability in development of heterozygotes and homozygotes

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1955.0029 ◽

1955 ◽

Vol 143 (913) ◽

pp. 561-578 ◽

Cited By ~ 46

Keyword(s):

Natural Selection ◽

Leaf Length ◽

Single Individual ◽

Physiological Properties ◽

Stability Of Development ◽

Maximum Stability ◽

Maximum Heterozygosity ◽

Per Se ◽

The Stability ◽

Genetical Structure

Heterozygotes show less variation between repetitive structures of a single individual, or between genetically like individuals, than do homozygotes in a number of naturally outbreeding species of plants and animals. This must generally (though not necessarily always) indicate a greater stability in development of heterozygotes than of homozygotes in these species. The greater stability has been variously interpreted as indicative of the superior genetic balance of heterozygotes which would be expected from the action of natural selection in outbreeding populations where partial heterozygosity will be the rule, and as a characteristic and inevitable property springing from a greater physiological versatility of the heterozygotic state per se . Observations on the stability properties of heterozygotes and homozygotes in inbreeding species should aid in reaching a decision between these views—a decision which is of basic importance to our understanding of the genetical structure and response to selection of both wild and domesticated populations. Nicotiana rustica naturally inbreeds to an extent which should reduce its heterozygosity to a half, or even less, of the maximum. Two experiments carried out for other purposes with this plant have provided evidence about its properties of stability in development. In respect of leaf length and capsule number there is no indication of genetical differences in stability within the material observed. In respect of plant height, F 1 's are less stable than inbred parents, where differences exist. Genetical differences also exist in respect of flowering time, but F 1 's and inbred parents show the same average stability. Thus the most, as well as the least, stable families are to be found among the inbred lines. Heterozygosity per se thus confers no greater stability of development in this partially inbreeding plant, and other inbreeding species support this conclusion. A re-examination of evidence from Drosophila melanogaster shows that maximum stability is not necessarily associated with maximum heterozygosity. Evidence obtained by Tebb and Thoday from their studies of the X -chromosome also shows that homozygotes can exhibit a developmental stability superior to that of heterozygotes. All these results are to be expected if stability in development reflects a genic balance produced by the action of natural selection, but find no obvious explanation if greater stability is referred to innate physiological properties of the heterozygotic state as such. Physiological assumptions must thus be made with caution, and in particular must not be allowed to prejudice genetical interpretation in the field of population studies.

Download Full-text