The effect of selection for resistance to clover infertility on the reproductive performances of Merino ewes grazed on oestrogenic pastures

1989 ◽  
Vol 40 (1) ◽  
pp. 165 ◽  
Author(s):  
KP Croker ◽  
RJ Lightfoot ◽  
TJ Johnson ◽  
NR Adams ◽  
MJ Carrick
Keyword(s):  
Adverse Effects ◽  
Standard Error ◽  
Growing Season ◽  
Realized Heritability ◽  
Summer Period ◽  
Histological Changes ◽  
Selection Programme ◽  
Selection For ◽  
And Control ◽  
Selection Of

Rams were bred from ewes which had either maintained their fertility after grazing highly oestrogenic pastures for three to seven years. or, over the same period grazed �control� on or lowly oestrogenic pastures In 1977 and 1978 these rams were joined with a random selection of ewes, which had been grazed on lowly oestrogenic pastures, to produce contemporary Resistant and Control ewes.The Resistant and Control ewes were split at weaning into groups which subsequently were grazed on oestrogenic or non-oestrogenic pastures during each pasture growing season (May to October) of the experiment During the dry spring-summer period the ewes were regrouped and entire rams were joined with them for 42 days from early in January to determine whether resistance to the development of clover infertility had been inherited.The reproductive performances of the ewes were measured from two until eight years of age over the period from 1979 to 1986. In addition, the masculinization of the vulvas was monitored, mucus product ion was measured in the second last year, and the histology of the cervixes was observed when the experiment was terminated.The fertility of the Resistant ewes was affected by the oestrogenic pasture in the later years of the experiment, but the level of depression was significantly lower than that measured in the Control ewes grazed on oestrogenic pasture The realized 'heritability' of the ewes' fertile lifetime on oestrogenic pasture was estimated to be 0.73 with a standard error of 0.30.This resistance was associated with histological changes, which confirmed that the Resistant ewes were protected against oestrogen-induced damage. These results support the hypothesis that res istance to the development of clover infertility was present in these ewesA more intensive selection programme involving both ewes and rams may impart a higher level of resistance to ewes This would reduce the adverse effects of oestrogenic pastures on ewe flock productivity.

scholarly journals Selection for the length of the spermatozoan midpiece in the mouse

1970 ◽  
Vol 16 (3) ◽  
pp. 261-275 ◽  
Author(s):  
D. M. Woolley
Keyword(s):  
Electron Microscope Study ◽  
Selection Response ◽  
Sperm Cells ◽  
Realized Heritability ◽  
Family Selection ◽  
Selected Lines ◽  
Selection Programme ◽  
Proportionate Change ◽  
The Subject ◽  
Selection For

SUMMARYA subcellular dimension, the length of the spermatozoan midpiece, has been the subject of a two-way selection programme in mice. After thirteen generations of within-family selection the divergence between the selected lines amounted to 5·4 phenotypic standard deviations. The realized heritability was found to be 0·76 ± 0·02, dominance and commonenvironmental effects being apparently very small. The reality of the selection response was verified in measurements on live spermatozoa. Other measurements have shown that the change in the length of the midpiece has been independent of its width, and has occurred without a proportionate change in the length of the main-piece of the flagellum. An electron microscope study has shown that the selection has, in fact, brought about changes in the quantity of mitochondrial material in the sperm cells.

scholarly journals Replicated selection for body weight in mice

1973 ◽  
Vol 22 (3) ◽  
pp. 291-321 ◽  
Author(s):  
D. S. Falconer
Keyword(s):  
Standard Error ◽  
Single Pair ◽  
Realized Heritability ◽  
Selected Lines ◽  
Random Drift ◽  
Single Experiment ◽  
Identical Manner ◽  
Selection For ◽  
The Asymmetry ◽  
Empirical Standard

SUMMARYThe variation in the response to selection was studied by replication of selected lines. A random-bred strain of mice was divided into six replicates. Two-way selection for 6-week weight was applied in an identical manner to each replicate, and each had an unselected control. Each line (6 large, 6 control, 6 small) was maintained by minimal inbreeding with 8 single-pair matings. The overall mean responses, both up and down, were linear and very regular for ten generations, with realized heritabilities of 40% upwards, 33% downwards and 37% for the divergence. The separate replicates, however, differed greatly in their realized heritabilities, with upward selection ranging from 25 to 46%, and downward selection from 16 to 50%. The theoretical prediction that, because of genetic drift, the standard error of a realized heritability is underestimated by the standard error of the regression of response on cumulated selection differential was borne out in this experiment. The empirical standard error, calculated from the observed variance between replicates, was more than twice as great as that of the regression. The empirical standard errors showed that the asymmetry between upward and downward responses was not significant. The variation between the replicates was ascribed mainly to random drift, which may seriously influence the conclusions about the realized heritability and the asymmetry of response that would be drawn from a single experiment with the population size of one of these replicates. After 23 generations of selection the large lines were approaching limits, and the limit appeared to be at the same level in all. The small lines showed an undiminished realized heritability after 23 generations, but the selection differentials were then so small that little progress was made. There was evidence of counter-acting natural selection. All aspects of productivity – proportion of fertile matings, litter size and weaning rate – declined in the control lines. The overall productivity of the large lines was a little below the controls, and that of the small lines was reduced to about half the level of the controls. The separate replicates differed from each other significantly in all the components of productivity.

Selection for carcass length in Large White pigs

1968 ◽  
Vol 10 (4) ◽  
pp. 359-372 ◽  
Author(s):  
J. E. Duckworth ◽  
W. Holmes
Keyword(s):  
Selection Pressure ◽  
Herd Size ◽  
Litter Production ◽  
Realized Heritability ◽  
Large White ◽  
Components Of Variance ◽  
Selection Programme ◽  
Selection For ◽  
One Year ◽  
Sib Selection

A sib selection programme for length of carcass was carried out for five generations within a closed herd of Large White pigs. A generation interval of one year was obtained.Litter production was good throughout the project and the numbers of pigs born and reared in the final generation were 11·2 and 10·3 respectively.Overall response to selection was predicted with reasonable success. The increase in length was associated with an increase in number of vertebrae.Heritability for length of carcass computed from the pooled components of variance was 0·53 ± 0·12. Realized heritability was 0·5 ± 0·1. No control strain was maintained.Correlated traits moved in the expected directions and responses were beneficial for traits such as backfat measurements and chest depth, but unfavourable for belly thickness and ham conformation. Carcass acceptability was not good initially and this deteriorated during the project. The difficulties involved in maintaining selection pressure and herd size are discussed. Abnormalities and lameness were recorded and did not increase systematically over the experiment.It is suggested that the specific relationships between ‘conformation’, carcass value and viability require further investigation with particular reference to length of leg and length of carcass.

scholarly journals Prospects for the use of a multi-tier narrow-stack installation in the selection of European radish

2021 ◽  
pp. 26-33
Author(s):  
S. M. Sirota ◽  
E. V. Pinchuk ◽  
E. G. Kozar ◽  
L. V. Bespalko ◽  
V. A. Stepanov
Keyword(s):  
Shade Tolerance ◽  
Growing Season ◽  
Limiting Factors ◽  
Hydroponic Cultivation ◽  
Early Ripening ◽  
Energy Consuming ◽  
Multi Level ◽  
Selection For ◽  
Selection Of ◽  
Vitamin Production

Relevance. Growing European radishes in protected soil on hydroponics provides year-round fresh vitamin production. For the autumn-winter turnover shade-tolerant varieties with a short growing season are necessary. For the spring-summer turnover, the resistance of the variety to high temperatures and premature stem formation is of particular importance. Selection of targeted radish varieties is an energy-consuming process, which can be optimized by using an open-type multi-tier narrow-stack hydroponics installation with a different combination of limiting factors for tiers (light, heat).Methods and results. In Federal Scientific Vegetable Center radish varieties were tested in different conditions. The informativeness of the tiers on the installation as backgrounds for selection for adaptability and specificity is determined. It was found that the assessment and selection of productivity and large-fruited is effectively carried out on 1-2 tiers; for resistance to premature stem formation – on 1 tier; for shade tolerance, early ripening, with a stable manifestation of the marketable mass of the root crop – on 4-5 tiers. Radish varieties were selected as the starting material for the suitability for hydroponic cultivation of intensive type and highly adaptive. The uniqueness of the use of a multi-level narrow column hydroponics for the purpose of radish breeding is shown. 

scholarly journals The Crab-eating Fox (Cerdocyon thous) as a secondary seed disperser of Eugenia umbelliflora (Myrtaceae) in a Restinga forest of southeastern Brazil

2009 ◽  
Vol 9 (2) ◽  
pp. 271-274 ◽  
Author(s):  
Eliana Cazetta ◽  
Mauro Galetti
Keyword(s):  
Seed Germination ◽  
Atlantic Forest ◽  
Southeastern Brazil ◽  
Plant Recruitment ◽  
Seed Disperser ◽  
Cerdocyon Thous ◽  
Selection For ◽  
Viable Seeds ◽  
And Control ◽  
Selection Of

The crab-eating fox (Cerdocyon thous) exhibits a very generalist habit and fruits compose a large proportion of its diet. However, few studies evaluated the importance of this animal as seed disperser. In the Restinga forest, in the Atlantic forest of Brazil, C. thous consumes fruits of Eugenia umbelliflora, a Myrtaceae species, which is dispersed chiefly by birds. This study evaluated the effects of gut transit on seed germination, and size selection of E. umbelliflora fruits by the crab-eating fox. We did not find differences on germination rates between seeds dispersed by foxes and control ones, but seeds dispersed by foxes germinated faster, which may be important for plant recruitment. Seeds consumed by C. thous were smaller than those available on the ground, indicating selection for small fruits. Regardless of the selection of small fruits, C. thous appears to be an important secondary disperser of E. umbelliflora, distributing large quantities of viable seeds of this Myrtaceae in the Restinga forest.

scholarly journals GENETIC CHANGE OF RECOMBINATION VALUE IN DROSOPHILA MELANOGASTER. I. ARTIFICIAL SELECTION FOR HIGH AND LOW RECOMBINATION AND SOME PROPERTIES OF RECOMBINATION-MODIFYING GENES

Genetics ◽  
1972 ◽  
Vol 70 (3) ◽  
pp. 419-432
Author(s):  
Margaret Gale Kidwell
Keyword(s):  
Genetic Change ◽  
Selection Line ◽  
Realized Heritability ◽  
Selected Lines ◽  
Gene Frequencies ◽  
Random Drift ◽  
High Line ◽  
Selection For ◽  
Recombination Value ◽  
Selection Of

ABSTRACT A high and low selection line were formed by individual selection of females on the basis of their recombination. In the high line, recombination between Gl and Sb was increased from 14.8 percent to about 30 percent in twelve generations, when a plateau was apparently reached. Realized heritability was 0.12. The absence of a response to selection for low recombination is attributed mainly to genetic random drift, and partially to directional dominance and directional gene frequencies. Natural selection was found to act against increases of recombination above a level of about twenty percent in the measured interval. High recombination tended to be recessive to low recombination. In both selected lines and unselected stocks, intervals proximal to the centromere tended to have a higher recombination variance than distal intervals.

scholarly journals Resource selection of a nomadic ungulate in a dynamic landscape

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246809
Author(s):  
Theresa S. M. Stratmann ◽  
Nandintsetseg Dejid ◽  
Justin M. Calabrese ◽  
William F. Fagan ◽  
Christen H. Fleming ◽  
...  
Keyword(s):  
Snow Cover ◽  
Resource Selection ◽  
Random Search ◽  
Population Level ◽  
Growing Season ◽  
Individual Level ◽  
Movement Trajectories ◽  
Selection For ◽  
The Individual ◽  
Selection Of

Nomadic movements are often a consequence of unpredictable resource dynamics. However, how nomadic ungulates select dynamic resources is still understudied. Here we examined resource selection of nomadic Mongolian gazelles (Procapra gutturosa) in the Eastern Steppe of Mongolia. We used daily GPS locations of 33 gazelles tracked up to 3.5 years. We examined selection for forage during the growing season using the Normalized Difference Vegetation Index (NDVI). In winter we examined selection for snow cover which mediates access to forage and drinking water. We studied selection at the population level using resource selection functions (RSFs) as well as on the individual level using step-selection functions (SSFs) at varying spatio-temporal scales from 1 to 10 days. Results from the population and the individual level analyses differed. At the population level we found selection for higher than average NDVI during the growing season. This may indicate selection for areas with more forage cover within the arid steppe landscape. In winter, gazelles selected for intermediate snow cover, which may indicate preference for areas which offer some snow for hydration but not so much as to hinder movement. At the individual level, in both seasons and across scales, we were not able to detect selection in the majority of individuals, but selection was similar to that seen in the RSFs for those individuals showing selection. Difficulty in finding selection with SSFs may indicate that Mongolian gazelles are using a random search strategy to find forage in a landscape with large, homogeneous areas of vegetation. The combination of random searches and landscape characteristics could therefore obscure results at the fine scale of SSFs. The significant results on the broader scale used for the population level RSF highlight that, although individuals show uncoordinated movement trajectories, they ultimately select for similar vegetation and snow cover.

Identifying Measurement Invariant Item Sets in Cross-Cultural Settings Using an Automated Item Selection Procedure

Methodology ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 177-188 ◽  
Author(s):  
Martin Schultze ◽  
Michael Eid
Keyword(s):  
Measurement Invariance ◽  
Optimal Solution ◽  
Selection Procedure ◽  
Cross Cultural ◽  
Item Selection ◽  
Ant System ◽  
Item Quality ◽  
Ant System Algorithm ◽  
Selection For ◽  
Selection Of

Abstract. In the construction of scales intended for the use in cross-cultural studies, the selection of items needs to be guided not only by traditional criteria of item quality, but has to take information about the measurement invariance of the scale into account. We present an approach to automated item selection which depicts the process as a combinatorial optimization problem and aims at finding a scale which fulfils predefined target criteria – such as measurement invariance across cultures. The search for an optimal solution is performed using an adaptation of the [Formula: see text] Ant System algorithm. The approach is illustrated using an application to item selection for a personality scale assuming measurement invariance across multiple countries.

ESTIMASI NILAI HERITABILITAS BOBOT IKAN MAS VARIETAS PUNTEN DALAM PROGRAM SELEKSI INDIVIDU

2016 ◽  
Vol 11 (3) ◽  
pp. 217
Author(s):  
Estu Nugroho ◽  
Budi Setyono ◽  
Mochammad Su’eb ◽  
Tri Heru Prihadi
Keyword(s):  
Body Weight ◽  
Selection Response ◽  
Base Population ◽  
Breeding Programs ◽  
Male And Female ◽  
Body Weight Trait ◽  
Population Selection ◽  
Selection For ◽  
Weight Trait ◽  
Selection Of

Program pemuliaan ikan mas varietas Punten dilakukan dengan seleksi individu terhadap karakter bobot ikan. Pembentukan populasi dasar untuk kegiatan seleksi dilakukan dengan memijahkan secara massal induk ikan mas yang terdiri atas 20 induk betina dan 21 induk jantan yang dikoleksi dari daerah Punten, Kepanjen (delapan betina dan enam jantan), Kediri (tujuh betina dan 12 jantan), Sragen (27 betina dan 10 jantan), dan Blitar (15 betina dan 11 jantan). Larva umur 10 hari dipelihara selama empat bulan. Selanjutnya dilakukan penjarangan sebesar 50% dan benih dipelihara selama 14 bulan untuk dilakukan seleksi dengan panduan hasil sampling 250 ekor individu setiap populasi. Seleksi terhadap calon induk dilakukan saat umur 18 bulan pada populasi jantan dan betina secara terpisah dengan memilih berdasarkan 10% bobot ikan yang terbaik. Calon induk yang terseleksi kemudian dipelihara hingga matang gonad, kemudian dipilih sebanyak 150 pasang dan dipijahkan secara massal. Didapatkan respons positif dari hasil seleksi berdasarkan bobot ikan, yaitu 49,89 g atau 3,66% (populasi ikan jantan) dan 168,47 g atau 11,43% (populasi ikan betina). Nilai heritabilitas untuk bobot ikan adalah 0,238 (jantan) dan 0,505 (betina).Punten carp breeding programs were carried out by individual selection for body weight trait. The base population for selection activities were conducted by mass breeding of parent consisted of 20 female and 21 male collected from area Punten, eight female and six male (Kepanjen), seven female and 12 male (Kediri), 27 female and 10 male (Sragen), 15 female and 11 male (Blitar). Larvae 10 days old reared for four moths. Then after spacing out 50% of total harvest, the offspring reared for 14 months for selection activity based on the sampling of 250 individual each population. Selection of broodstock candidates performed since 18 months age on male and female populations separately by selecting based on 10% of fish with best body weight. Candidates selected broodstocks were then maintained until mature. In oder to produce the next generation 150 pairs were sets and held for mass spawning. The results revealed that selection response were positive, 49.89 g (3.66%) for male and 168.47 (11.43%) for female. Heritability for body weight is 0.238 (male) and 0.505 (female).

MODEL OF SOCIAL POTENTIAL OF CHILDHOOD IN THE RUSSIAN REGIONS: THE RESULTS OF EXPERIMENTS

2019 ◽  
pp. 152-162
Author(s):  
A.G. Filipova ◽  
A.V. Vysotskaya
Keyword(s):  
Third Wave ◽  
Russian Regions ◽  
The Third ◽  
Control Factors ◽  
Social Potential ◽  
System Input ◽  
Optimal Values ◽  
Fixed Ideal ◽  
And Control ◽  
Selection Of

The article presents the results of mathematical experiments with the system «Social potential of childhood in the Russian regions». In the structure of system divided into three subsystems – the «Reproduction of children in the region», «Children’s health» and «Education of children», for each defined its target factor (output parameter). The groups of infrastructure factors (education, health, culture and sport, transport), socio-economic, territorial-settlement, demographic and en-vironmental factors are designated as the factors that control the system (input parameters). The aim of the study is to build a model îf «Social potential of childhood in the Russian regions», as well as to conduct experiments to find the optimal ratio of the values of target and control factors. Three waves of experiments were conducted. The first wave is related to the analysis of the dynam-ics of indicators for 6 years. The second – with the selection of optimal values of control factors at fixed ideal values of target factors. The third wave allowed us to calculate the values of the target factors based on the selected optimal values of the control factors of the previous wave.

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