An evaluation of a new rhombic grid selection, gridded mass selection and simple mass selection methods for yield improvement in wheat

Euphytica ◽  
1988 ◽  
Vol 38 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Solomon Kibite
Keyword(s):  
Mass Selection ◽  
Selection Methods ◽  
Yield Improvement ◽  
Simple Mass ◽  
Grid Selection

scholarly journals Size of population required for artificial selection

1980 ◽  
Vol 35 (1) ◽  
pp. 85-105 ◽  
Author(s):  
F. W. Nicholas
Keyword(s):  
Genetic Drift ◽  
Coefficient Of Variation ◽  
Directional Selection ◽  
Mass Selection ◽  
Selection Line ◽  
Short Term ◽  
Selection Programme ◽  
Standard Normal ◽  
Simple Mass ◽  
Term Response

SUMMARYIt is widely acknowledged that genetic drift is an important source of variation in response to artificial directional selection. How large should a selection line be in order to reduce the effect of genetic drift to an acceptably low level?This paper investigates two criteria that can be used to answer this question in relation to short-term response to selection. The first criterion is coefficient of variation of response, and the second criterion is chance of success, where a successful selection programme is one in which the observed response is greater than a certain proportion, β, of expected response.For a simple mass selection programme with intensity i and heritability h2, the size of population required in order for the coefficient of variation of response to be γ after t generations, is approximately 2/(γih)2t, and the size required for the chance of success to be α after t generations is approximately 2{zα/(β−l)ih}2/t, where zα is the standard normal deviate corresponding to the probability α.As an example, suppose it is required that after t generations the coefficient of variation of response be 10% or that there be a 90% chance of achieving at least 9/10 of expected response. Since ih ≤ 2 in most selection programmes, the size of population required is at least 50/t or 82/t respectively. If ih ≤ 1, the corresponding sizes are 200/t and 328/t.Results are extended to enable the calculation of size of population required for any type of artificial directional selection programme, including those in which generations overlap.

scholarly journals Heritability of distichiasis in Havanese dogs in Norway

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kim K. L. Bellamy ◽  
Frode Lingaas ◽  
Per Madsen
Keyword(s):  
Animal Welfare ◽  
Threshold Model ◽  
Clinical Signs ◽  
Selection Response ◽  
Mass Selection ◽  
Corneal Disease ◽  
Eye Health ◽  
Norwegian Population ◽  
High Heritability ◽  
Simple Mass

Abstract Background Distichiasis is a presumed inherited eyelid disease, characterized by misplaced eyelashes. The effect on eye health and animal welfare varies between individuals; most mild cases show no clinical signs, but some affected animals develop painful corneal disease. In this study, we investigated the prevalence and heritability of distichiasis in the Norwegian population of Havanese dogs. Results A total of 1156 Havanese were included in the study. Out of these, 168 were affected with distichiasis, making the prevalence in our sample 14.5% (95% CI 12.5–16.6%). There was no sex predisposition. Most affected individuals were graded “mildly affected”. The estimates generally showed high heritabilities, which varied between 0.276 (linear model) and 0.720 (Bayesian threshold model). The linear estimates, after conversion to the underlying scale (h2l = 0.664–0.674), corresponds well to the results of the Bayesian models. Conclusions The estimated heritability of distichiasis in Havanese is high and the prevalence is moderate. The high heritability indicate that a significant selection response could be obtained by simple mass selection. To secure good animal welfare, it’s important to control the number of affected individuals and especially the severely affected.

Impact of genotype multiply environment interaction on response to selection in sugarcane

1992 ◽  
Vol 32 (6) ◽  
pp. 731 ◽  
Author(s):  
JK Bull ◽  
DM Hogarth ◽  
KE Basford
Keyword(s):  
Cost Effective ◽  
Genotype X Environment Interaction ◽  
Mass Selection ◽  
Environment Interaction ◽  
Selection Methods ◽  
Family Selection ◽  
Random Group ◽  
Genotype X Environment ◽  
Experiment Station ◽  
The Impact

The impact of genotype x environment interaction on the response to 3 methods of selection in sugarcane was assessed over 3 locations and 3 cropyears. The 3 selection methods considered were 2 previously used procedures, mass (individual) selection using a visual appraisal of clonal performance and family selection using selection rate, and a new procedure, family selection using a net merit grade (NMG) derived from weighing family plots. Within the 2 forms of family selection, light mass selection based on a visual appraisal of clonal performance was used to reject the poorest clones. The gains from selection, cdculated as the deviation in performance of the select groups from the performance of a group of randomly chosen clones, were assessed for each of these 3 methods. All 3 selection methods gave similar gains over the random group when averaged over all locations and crop-years. Family selection based on NMG is recommended for routine use as it is the least labour-intensive and most cost-effective. Genotype x environment interaction, on both a family and clonal basis, was large enough to affect the gains made from selection. These effects provided some support for location-specific selection. Furthermore, selections based on the results from the central experiment station produced relatively poor gains when assessed over all locations and crop-years. This indicates that the experiment station may be a poor location for centralised selection. The use of at least 1 other location may provide a buffer against infrequent environmental factors rendering worthless family or clonal discrimination at any particular location.

Fairness reactions to selection methods: A Romanian study

2009 ◽  
Author(s):  
Dan Ispas ◽  
Alexandra Ilie ◽  
Dragos Iliescu
Keyword(s):  
Selection Methods
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