COMPARISON OF FOUR METHODS OF SELECTION FOR RESISTANCE TO LEPTOSPHAERULINA BRIOSIANA IN ALFALFA

1979 ◽  
Vol 21 (2) ◽  
pp. 179-186 ◽  
Author(s):  
R. R. Hill Jr. ◽  
K. T. Leath
Keyword(s):  
Selection Method ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection Methods ◽  
Family Selection ◽  
Colletotrichum Trifolii ◽  
Family Types ◽  
Medicago Sativa L ◽  
Selection For

Three cycles of selection for resistance to Leptosphaerulina briosiana (Poll.) Graham &Luttrell were conducted in two alfalfa (Medicago sativa, L.) germplasm pools, MSA and MSB. Each germplasm pool was used to compare four methods of selection: phenotypic recurrent, half-sib family, full-sib family, and alternating generations of selfed family and half-sib family. Response to selection for resistance to L. briosiana was greater in MSA than in MSB. Differences between selection methods were not significant. Selection for resistance to L. briosiana generally increased resistance to Stemphylium botryosum Wallr., but the magnitude of the correlated response varied with germplasm pool and selection method. The initial selfed families in both germplasm pools were significantly less resistant to Colletotrichum trifolii Bain than the other family types. Resistance to C. trifolii increased with selfed family selection for resistance to L. briosiana in MSA but not in MSB.

Heritability, correlated response, and indirect selection involving spectral reflectance indices and grain yield in wheat

2007 ◽  
Vol 58 (5) ◽  
pp. 432 ◽  
Author(s):  
M. A. Babar ◽  
M. van Ginkel ◽  
M. P. Reynolds ◽  
B. Prasad ◽  
A. R. Klatt
Keyword(s):  
Grain Yield ◽  
Spectral Reflectance ◽  
Genetic Correlations ◽  
Grain Filling ◽  
Indirect Selection ◽  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Selection For ◽  
Reflectance Indices

The objectives of this study were to assess the potential of using spectral reflectance indices (SRIs) as an indirect selection tool for grain yield in wheat under irrigated conditions. This paper demonstrates the genetic correlation between grain yield and SRIs, heritability and expected response to selection for grain yield and SRIs, correlated response to selection for grain yield estimated from SRIs, and efficiency of indirect selection for grain yield using SRIs in different spring wheat populations. Four field experiments, GHIST (15 CIMMYT globally adapted genotypes), RLs1 (25 random F3-derived families), RLs2 (36 random F3-derived families), and RLs3 (64 random F5-derived families) were conducted under irrigated conditions at the CIMMYT research station in north-west Mexico in 3 different years. Spectral reflectance was measured at 3 growth stages (booting, heading, and grain filling) and 7 SRIs were calculated using average values of spectral reflectance at heading and grain filling. Five previously developed SRIs (PRI, WI, RNDVI, GNDVI, SR), and 2 newly calculated SRIs (NWI-1 and NWI-2) were evaluated in the experiments. In general, the within- and between-year genetic correlations between grain yield and SRIs were significant. Three NIR-based indices (WI, NWI-1, and NWI-2) showed higher genetic correlations (0.73–0.92) with grain yield than the other indices (0.35–0.67), and these observations were consistent in all populations. Broad-sense heritability estimates for all indices were in general moderate to high (0.60–0.80), and higher than grain yield (0.45–0.70). The realised heritability for the 3 NIR-based indices was higher than for the other indices and for grain yield itself. Expected response to selection for all indices was moderate to high (0.54–0.85). The correlated response for grain yield estimated from the 3 NIR-based indices (0.59–0.64) was much higher than the correlated response for grain yield estimated from the other indices (0.31–0.46), and the efficiency of indirect selection for these 3 NIR-based indices was 90–96% of the efficiency of direct selection for grain yield. These results demonstrate the potential for using the 3 NIR-based SRI tools in breeding programs for selecting for increased genetic gains for yield.

scholarly journals The number of loci affecting a quantitative trait in Drosophila melanogaster revealed by artificial selection

1983 ◽  
Vol 42 (2) ◽  
pp. 137-149 ◽  
Author(s):  
Araceli Gallego ◽  
Carlos López-Fanjul
Keyword(s):  
Initial Response ◽  
Selection Method ◽  
Base Population ◽  
Response To Selection ◽  
Family Selection ◽  
Selected Lines ◽  
Additive Variance ◽  
Bristle Number ◽  
Selection Limit ◽  
Selection For

SUMMARYIndividual and within-full-sib family selection for low sternopleural bristle number was carried out for 17 generations, with six replicate lines for each selection method. Our results can be summarized as follows: (1) the response to selection was exhausted very quickly, (2) the additive variance of the selected lines declined rapidly, (3) the variation in response to selection decreased as selection progressed, (4) genetic differences among replicates at the selection limit were small, (5) individual selection resulted in a higher initial response than within-family selection, but similar limits were achieved with both procedures. These observations are consistent with the hypothesis that the pattern of response to selection is due to the segregation in the base population of only a few loci with large effects, at intermediate frequencies.

Efficiency of conversion of food to wool. I. Correlated response to selection for high and low clean wool weight

1960 ◽  
Vol 11 (5) ◽  
pp. 836 ◽  
Author(s):  
CHS Dolling ◽  
RW Moore
Keyword(s):  
The Other ◽  
Correlated Response ◽  
Response To Selection ◽  
Merino Sheep ◽  
Wool Production ◽  
The Family ◽  
Selection For ◽  
The Difference ◽  
Selection Of

The offspring of two families of medium Peppin Merino sheep, one family being selected for high and the other for low clean wool weight per head at 15-16 months of age under grazing conditions, have also been shown to differ significantly in the ratio of wool production to food eaten in pens, on a ration slightly above maintenance. These ratios were in the proportion 108 : 100, and the difference between the families can be taken as reflecting closely a difference in net efficiency of conversion of food to wool. It may be concluded that selection for high clean wool weight per head under grazing conditions had also resulted in the selection of more efficient animals. Clean wool production per head in the two families was in the ratio 110 : 100 in the pens, compared with 124 : 100 under grazing. The difference under grazing probably results from both the higher efficiency of the family selected for high clean wool weight and a higher grazing intake by this family.

Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera
Keyword(s):  
Litter Size ◽  
Correlated Response ◽  
Quality Traits ◽  
Response To Selection ◽  
Fat Quality ◽  
Selection For

scholarly journals Using systematic sampling selection for Monte Carlo solutions of Feynman-Kac equations

2008 ◽  
Vol 40 (2) ◽  
pp. 454-472 ◽  
Author(s):  
Ivan Gentil ◽  
Bruno Rémillard
Keyword(s):  
Monte Carlo ◽  
Markov Chains ◽  
Selection Method ◽  
Systematic Sampling ◽  
Selection Methods ◽  
Convergence Properties ◽  
Main Motivation ◽  
Empirical Basis ◽  
Convergence Results ◽  
Selection For

While the convergence properties of many sampling selection methods can be proven, there is one particular sampling selection method introduced in Baker (1987), closely related to ‘systematic sampling’ in statistics, that has been exclusively treated on an empirical basis. The main motivation of the paper is to start to study formally its convergence properties, since in practice it is by far the fastest selection method available. We will show that convergence results for the systematic sampling selection method are related to properties of peculiar Markov chains.

scholarly journals Selection for growth on normal and reduced protein diets in mice: I. Direct and correlated responses for growth

1987 ◽  
Vol 50 (1) ◽  
pp. 7-15 ◽  
Author(s):  
B. Vivi Hunnicke Nielsen ◽  
Søren Andersen
Keyword(s):  
Protein Level ◽  
Protein Diet ◽  
Correlated Response ◽  
Family Selection ◽  
Direct Response ◽  
Protein Levels ◽  
Selection Environment ◽  
Normal Protein Diet ◽  
Selection For ◽  
Protein Diets

SummaryMice were selected for growth from 3 to 9 weeks of age on a normal protein diet (N) containing 19·3% protein and a reduced protein diet (R) containing 5·1% protein. On each diet there were 3 high (H), 3 low (L) and 3 unselected control (C) lines. After 6 generations of selection, half of the mice in each line were tested on each diet. Responses were obtained when selecting for both increased and decreased growth on both diets. The realized heritabilities from within-family selection were 33 and 26% for the divergences on the normal and reduced protein diets, respectively. Consistent genotype-environment interactions were found when all lines were tested on both diets in generation 7. Performance on each protein level was best improved by selection on that protein level. Further, the correlated response was significantly less than the direct response when selecting on both diets. The estimates of the genetic correlation between growth on the two protein levels were low, rN = 0·16 from selection on the normal protein diet and rR = 0·51 from selection on the reduced protein diet. Selection resulted in a change in environmental sensitivity in the lines, dependent on the diet and direction of selection. The average of the divergences on the two diets was not dependent on the selection environment.

Group feeding behavior of brown trout is a correlated response to selection for growth shaped by the environment

2007 ◽  
Vol 37 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Thierry Boujard ◽  
Julien Ramezi ◽  
Marc Vandeputte ◽  
Laurent Labbé ◽  
Muriel Mambrini
Keyword(s):  
Feeding Behavior ◽  
Brown Trout ◽  
Correlated Response ◽  
Response To Selection ◽  
Group Feeding ◽  
Selection For

Corrigendum - Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

1968 ◽  
Vol 19 (1) ◽  
pp. 79
Author(s):  
HN Turner ◽  
CHS Dolling ◽  
JF Kennedy
Keyword(s):  
Fibre Diameter ◽  
The Other ◽  
Correlated Response ◽  
Mass Selection ◽  
Skin Area ◽  
Response To Selection ◽  
High Degree ◽  
Second Period ◽  
Final Selection ◽  
Staple Length

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

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