Actual yield advance from selection for visual score and yield

1995 ◽  
Vol 75 (1) ◽  
pp. 187-189 ◽  
Author(s):  
T. C. Helms ◽  
J. H. Orf ◽  
R. A. Scott
Keyword(s):  
The Other ◽  
Selected Lines ◽  
Physiological Maturity ◽  
Population Mean ◽  
Visual Score ◽  
Glycine Max L ◽  
Unselected Population ◽  
Selection For ◽  
Testing Environments ◽  
Actual Yield

The ability of soybean [Glycine max (L) Merr.] breeders to select for yield, based on visual score is unknown. Our objectives were (i) to determine whether a sample of three breeders were able to visually score soybean plots for yield and to identify lines that were higher yielding than the population mean; and (ii) to compare selection for visual score versus selection solely for weighed yield. Visual score was rated at physiological maturity in two environments. Experimental lines were evaluated for weighed yield in six environments. Lines were selected for weighed yield or visual score, based on data from two selection environments, and actual yield advance was measured in the other four testing environments. Two breeders identified BP-derived lines that averaged higher than the unselected population mean yield when selection was based solely on the visual score. Two of three breeders selected lines, based on visual score, that were as high yielding in testing environments as lines selected solely for weighed yield. Key words: Soybean, visual score

Nearest-neighbor-adjusted means as a selection criterion within two soybean populations

1995 ◽  
Vol 75 (4) ◽  
pp. 857-863 ◽  
Author(s):  
T. C. Helms ◽  
J. H. Orf ◽  
R. A. Scott
Keyword(s):  
Nearest Neighbor ◽  
Selection Criterion ◽  
Mean Square ◽  
Selection Environment ◽  
Adjusted Means ◽  
Glycine Max L ◽  
Selection For ◽  
Testing Environments ◽  
Actual Yield ◽  
Actual Gain

When the nearest-neighbor adjustment (NNA) reduces the magnitude of the residual mean square, plant breeders have the option of selecting genotypes on the basis of the NNA or unadjusted (UNADJ) means. The actual gain from selection for a specific set of experiments can be compared when selection is based on each criterion. Our objective was to compare the yields of lines selected with the NNA and UNADJ criteria. Three hundred soybean [Glycine max (L.) Merr.] experimental lines were evaluated in six environments. Each environment was considered a selection environment, and the actual yield advance was measured in the other five environments. In 11 out of 12 cases, the lines selected by the NNA and UNADJ criteria were equal in yield when compared in testing environments. Interlocation correlations were similar for both models. Predicted genetic gain was overestimated more often when using the NNA than the UNADJ model. Key words:Glycine max, heritability

Predicted and actual yield advance in a bi-parental and backcross-derived soybean population

1994 ◽  
Vol 74 (1) ◽  
pp. 15-18
Author(s):  
T. C. Helms ◽  
J. H. Orf ◽  
R. A. Scott
Keyword(s):  
Glycine Max ◽  
Utility Function ◽  
Key Words ◽  
Genetic Gain ◽  
Genetic Variance ◽  
Plant Introduction ◽  
Physiological Maturity ◽  
Glycine Max L ◽  
The Mean ◽  
Actual Yield

Improved soybean [Glycine max (L.) Merr.] lines that include a plant introduction as one parent may be derived from a bi-parental (BP) or backcross (BC1) population. The number of BC1 families may be small in some instances because of a lack of successful crossing. The objectives of our experiment were to (1) compare the mean, genetic variance and distribution of lines from a BC1 population derived from only a few BC1 families with those from a BP-derived lines; (2) compare the BP and BC1 population mean with the mid-parent mean; and (3) evaluate the mean yield of the superior 10% of lines within each population. Two BC1F1 plants were selfed, and 75 random lines were derived from each plant. The mean yield, physiological maturity and plant height of BP-derived lines were greater than the mid-parent means. The genetic variance among BC1-derived lines was much smaller than among BP-derived lines. A utility function that combines mean yield and expected genetic gain identified the BC1 population as the superior population. Key words: Soybean, backcross, bi-parental, genetic gain

scholarly journals The ecological genetics of growth in Drosophila 4. The influence of larval nutrition on the manifestation of dominance

1961 ◽  
Vol 2 (3) ◽  
pp. 346-360 ◽  
Author(s):  
Forbes W. Robertson
Keyword(s):  
Body Size ◽  
Cell Size ◽  
Large Body ◽  
Ecological Genetics ◽  
Selected Lines ◽  
Pacific Population ◽  
Unselected Population ◽  
Selection For ◽  
Different Strains ◽  
Synthetic Media

(1) Two lines have been selected for small wing cell size from the cage Pacific population. Body size was reduced by about 10% and 15% in the two lines which did not regress when selection was relaxed.(2) The effects of crossing each line to the unselected population has been determined in a number of repeated tests on the live yeast medium and also on various sub-optimal synthetic media.(3) The size of the F1, relative to the size of the parents, is greatly influenced by the composition of the larval diet. The F1 may coincide with the mid-parent value but generally significantly exceeds it and is often the same size as the unselected parent population.(4) In crosses to an unselected population on alternative media the F1 was either the same size as the unselected population or exceeded it.(5) Crosses between the selected lines produced an F1 which exceeded the larger parent but remained well below the level of the unselected population.(6) To test for interaction between genes at different loci, chromosomes from the unselected population were substituted in the genetic background of each of the selected lines to provide an array of genotypes in which one, two or three pairs of major chromosomes had homologues derived from different strains. Leastsquares analysis indicated differences between the lines in the distribution of effects among the chromosomes together with the presence of interaction between chromosomes and this was greater for the substitutions in the line which showed the greater consistency of recessive behaviour in crosses to the unselected population.(7) At the end of the selection experiment two lines were selected for large body size from the F2 of the cross between the two selected lines. Both responded to selection for three to four generations and then fluctuated at a level slightly below that of the unselected population.(8) The physiological changes which involve correlated changes in body and cell size differ from those which result from selection for smaller body size, at least in the early stages of such selection, and are associated with differences in genetic behaviour. The apparently recessive property, which involves extensive non-allelic interaction, is progressively established during the course of selection. Apparently selection for smaller cell size is particularly effective in disturbing the normal homeostasis of growth and is accompanied by relatively greater loss of heterozygosis than is likely with equivalent reduction in size due to selection for smaller body as opposed to cell size.

scholarly journals SELECTION FOR BLOOD PRESSURE LEVELS IN MICE

Genetics ◽  
1974 ◽  
Vol 76 (3) ◽  
pp. 537-549
Author(s):  
Gunther Schlager
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Population Bottleneck ◽  
Control Line ◽  
Selected Lines ◽  
High Line ◽  
Selection For ◽  
Random Control

ABSTRACT Response to two-way selection for systolic blood pressure was immediate and continuous for about eight generations. In the twelfth generation, the High males differed from the Low males by 38 mmHG; the females differed by 39 mmHg. There was little overlap between the two lines and they were statistically significant from each other and from the Random control line. There appeared to be no more additive genetic variance in the eleventh and twelfth generations. Causes for the cessation of response are explored. This is probably due to a combination of natural selection acting to reduce litter sizes in the Low line, a higher incidence of sudden deaths in the High line, and loss of favorable alleles as both selection lines went through a population bottleneck in the ninth generation.—In the eleventh generation, the selected lines were used to produce F1, F2, and backcross generations. A genetic analysis yielded significant additive and dominance components in the inheritance of systolic blood pressure.

The effect of exposure to conspecifics on restlessness in the parasitoid wasp Nasonia vitripennis (Hymenoptera: Pteromalidae)

2007 ◽  
Vol 139 (5) ◽  
pp. 678-684 ◽  
Author(s):  
B.H. King
Keyword(s):  
Habitat Quality ◽  
Parasitoid Wasp ◽  
Poor Quality ◽  
The Other ◽  
Dispersal Ability ◽  
Nasonia Vitripennis ◽  
Adult Females ◽  
Selection For ◽  
The Difference ◽  
Abundance And Distribution

AbstractWhen habitat quality is variable, there should be strong selection for the ability to detect and respond to the variation. Adult females of the parasitoid wasp Nasonia vitripennis (Walker) are known to increase their restlessness (the proportion of time in locomotion) both during and after exposure to a poor quality host. Doing so provides a mechanism for leaving a poor host and potentially finding a better host. This study examined whether restlessness also changes in response to competition as indicated by the presence of adult conspecifics. Both restlessness and the probability of dispersing across an inhospitable environment were greater when a female was with another female than when she was alone. However, restlessness did not remain elevated after the other female was removed. In contrast with females, restlessness of males did not increase either during or after exposure to other males, and the probability of dispersing across an inhospitable environment was unaffected by the presence of another male. The difference between females and males may be related to differences in dispersal ability and in the abundance and distribution of hosts versus mates.

scholarly journals VARIATION IN DIGESTIBILITY DECLINE WITH ADVANCE IN MATURITY AMONG TIMOTHY (Phleum pratense L.) GENOTYPES

1986 ◽  
Vol 66 (2) ◽  
pp. 323-328 ◽  
Author(s):  
A. R. McELROY ◽  
B. R. CHRISTIE
Keyword(s):  
Forage Quality ◽  
Phleum Pratense ◽  
In Vitro Digestibility ◽  
Single Population ◽  
Population Mean ◽  
Unit Increase ◽  
Selection For ◽  
Phleum Pratense L

The in vitro digestibility (IVD) of timothy (Phleum pratense L.) declines with advance in maturity. Forage quality reductions resulting from late harvesting could be minimized by developing cultivars with reduced IVD decline during maturation. This study examines variation for IVD decline among timothy genotypes. Clones originating from a single population were grown in simulated swards (100 plants m−2) at two Ontario locations in 1980 and 1981. Harvests were made every 5–6 d from early heading to late anthesis. Relative IVD declines were determined by regressing genotype performance on the population mean over several harvests. Considerable variation was found for relative IVD decline, but this parameter was not associated with IVD at early heading. Genotypes were identified which showed high IVD at heading and a 20% reduction in digestibility decline from heading to late anthesis. Changes in IVD were not associated with changes in the leaf content of forage. It is concluded that selection for reduced IVD decline, in addition to high digestibility at heading, might result in a 2–3% unit increase at anthesis.Key words: Timothy, Phleum pratense L., in vitro digestibility, IVD, IVD decline

scholarly journals Evaluation of Resistance Development in Bemisia tabaci Genn. (Homoptera: Aleyrodidae) in Cotton against Different Insecticides

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 996
Author(s):  
Muhammad Zaryab Khalid ◽  
Sohail Ahmed ◽  
Ibrahim Al-ashkar ◽  
Ayman EL Sabagh ◽  
Liyun Liu ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
The Other ◽  
Resistance Development ◽  
Susceptible Population ◽  
Low Level ◽  
Development Of Resistance ◽  
Major Pest ◽  
Selection For ◽  
High Level ◽  
Very High

Cotton is a major crop of Pakistan, and Bemisia tabaci (Homoptera: Aleyrodidae) is a major pest of cotton. Due to the unwise and indiscriminate use of insecticides, resistance develops more readily in the whitefly. The present study was conducted to evaluate the resistance development in the whitefly against the different insecticides that are still in use. For this purpose, the whitefly population was selected with five concentrations of each insecticide, for five generations. At G1, compared with the laboratory susceptible population, a very low level of resistance was observed against bifenthrin, cypermethrin, acetamiprid, imidacloprid, thiamethoxam, nitenpyram, chlorfenapyr, and buprofezin with a resistance ratio of 3-fold, 2-fold, 1-fold, 4-fold, 3-fold, 3-fold, 3-fold, and 3-fold, respectively. However, the selection for five generations increased the resistance to a very high level against buprofezin (127-fold), and to a high level against imidacloprid (86-fold) compared with the laboratory susceptible population. While, a moderate level of resistance was observed against cypermethrin (34-fold), thiamethoxam (34-fold), nitenpyram (30-fold), chlorfenapyr (29-fold), and acetamiprid (21-fold). On the other hand, the resistance was low against bifenthrin (18-fold) after selection for five generations. A very low level of resistance against the field population of B. tabaci, at G1, showed that these insecticides are still effective, and thus can be used under the field conditions for the management of B. tabaci. However, the proper rotation of insecticides among different groups can help to reduce the development of resistance against insecticides.

scholarly journals Development of bioactive/active additives based on essential oils: A review

2020 ◽  
Vol 3 (4) ◽  
pp. 60-67
Author(s):  
Jessica Alarcón-Moyano ◽  
◽  
Silvia Matiacevich ◽  
Keyword(s):  
Medicinal Plants ◽  
Essential Oil ◽  
Essential Oils ◽  
Freeze Drying ◽  
The Other ◽  
Wall Material ◽  
Oil Oxidation ◽  
Active Additive ◽  
Wall Materials ◽  
Selection For

The use of bioactive/active additives has been increasing in recent years, especially those derived from medicinal plants such as essential oils. However, due to essential oil oxidation it is necessary to protect it by encapsulation techniques such as: emulsion, spray- and/or freeze-drying as the most economical techniques. On the other hand, an important factor is to determine the appropriate wall material to obtain a prolonged or controlled release in the food or in the organism. Therefore, several factors affect the release of the compounds such as the type, amount of wall material and/or combination of wall materials. Therefore, the knowledge of all the aforementioned factors is important in order to make an adequate selection for the development of a bioactive/active additive based on essential oils.

scholarly journals Inbreeding parents should invest more resources in fewer offspring

2016 ◽  
Author(s):  
A. Bradley Duthie ◽  
Aline M. Lee ◽  
Jane M. Reid
Keyword(s):  
General Theory ◽  
Evolutionary Dynamics ◽  
Inbreeding Avoidance ◽  
The Other ◽  
Trade Off ◽  
Offspring Number ◽  
Focal Female ◽  
Special Cases ◽  
Selection For ◽  
Joint Consideration

AbstractInbreeding increases parent-offspring relatedness and commonly reduces offspring viability, shaping selection on reproductive interactions involving relatives and associated parental investment (PI). Nevertheless, theories predicting selection for inbreeding versus inbreeding avoidance and selection for optimal PI have only been considered separately, precluding prediction of optimal PI and associated reproductive strategy given inbreeding. We unify inbreeding and PI theory, demonstrating that optimal PI increases when a female's inbreeding decreases the viability of her offspring. Inbreeding females should therefore produce fewer offspring due to the fundamental trade-off between offspring number and PI. Accordingly, selection for inbreeding versus inbreeding avoidance changes when females can adjust PI with the degree that they inbreed. In contrast, optimal PI does not depend on whether a focal female is herself inbred. However, inbreeding causes optimal PI to increase given strict monogamy and associated biparental investment compared to female-only investment. Our model implies that understanding evolutionary dynamics of inbreeding strategy, inbreeding depression, and PI requires joint consideration of the expression of each in relation to the other. Overall, we demonstrate that existing PI and inbreeding theories represent special cases of a more general theory, implying that intrinsic links between inbreeding and PI affect evolution of behaviour and intra-familial conflict.

THE RELATION BETWEEN NATURAL FECUNDITY AND RESPONSE TO FOLLICLE-STIMULATING HORMONE

1962 ◽  
Vol 25 (1) ◽  
pp. 137-144 ◽  
Author(s):  
ANNE McLAREN
Keyword(s):  
Artificial Selection ◽  
Response Curve ◽  
Follicle Stimulating Hormone ◽  
Ovarian Response ◽  
Ovulation Rate ◽  
The Other ◽  
Principal Effect ◽  
Low Levels ◽  
Selection For ◽  
Stimulating Hormone

SUMMARY A study was made of the response to induced ovulation of female mice from strains in which the spontaneous ovulation rate had increased as a result of artificial selection for litter size. In response to standard doses of follicle-stimulating hormone (FSH) within the physiological range, the number of eggs shed differed significantly among the three strains tested, in the direction expected on the basis of their spontaneous ovulation rates. This indicates that the principal effect of selection has been to increase the sensitivity of the ovary to FSH. In one strain, the possibility remains open that there may also have been some increase in the amount of FSH available. In response to larger doses of FSH, females from the strain with the highest spontaneous ovulation rate shed significantly fewer eggs than the other two groups. Selection must therefore have altered the shape of the dose-response curve, increasing the ovarian response at low levels of hormone and decreasing it at high levels.

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