scholarly journals Long-term selection of biparental crosses: a comparison among genomic methods and phenotypic selection

2019 ◽  
Author(s):  
Rafael Storto Nalin
Keyword(s):  
Phenotypic Selection ◽  
Term Selection ◽  
Selection Of

Individuals, hierarchies and processes: towards a more complete evolutionary theory

Paleobiology ◽  
1984 ◽  
Vol 10 (2) ◽  
pp. 146-171 ◽  
Author(s):  
Elisabeth S. Vrba ◽  
Niles Eldredge
Keyword(s):  
Downward Causation ◽  
Species Selection ◽  
Process Selection ◽  
Term Selection ◽  
Hierarchical Levels ◽  
Character Variation ◽  
Long Term Trend ◽  
Interlevel Causation ◽  
Selection Of

Hierarchy is a central phenomenon of life. Yet it does not feature as such in traditional biological theory. The genealogical hierarchy is a nested organization of entities at ascending levels. There are phenomena common to all levels: (1) Entities such as genomic constituents, organisms, demes, and species are individuals. (2) They have aggregate characters (statistics of characters of subparts), but also emergent characters (arising from organization among subparts). Character variation changes by (3) introduction of novelty and (4) sorting by differential birth and death. Causation of introduction and sorting of variation at each level may be (5) upward from lower levels, (6) downward from higher levels, or (7) lodged at the focal level. The term “selection” applies to only one of the possible processes which cause sorting at a focal level. Neo-Darwinian explanations are too narrow, both in the levels (of genotypes and phenotypes) and in the directive process (selection) which are stressed. The acknowledgment of additional, hierarchical phenomena does not usually extend beyond lip service. We urge that interlevel causation should feature centrally in explanatory hypotheses of evolution. For instance, a ready explanation for divergence in populations is “selection of random mutants.” But upward causation from genome dynamics (or downward causation from the hierarchical organism) to the directed introduction of mutants may be more important in a given case. Similarly, a long-term trend is traditionally explained as additive evolution in populations. But sorting among species may be the cardinal factor, and the cause may not be species selection but upward causation from lower levels. A general theory of biology is a theory of hierarchical levels—how they arise and interact. This is a preliminary contribution mainly to the latter question.

scholarly journals Optimum selection intensities in artificial selection programmes: an experimental evaluation

1977 ◽  
Vol 30 (2) ◽  
pp. 115-119 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Experimental Evaluation ◽  
Selection Intensity ◽  
Effective Population ◽  
Term Selection ◽  
Optimum Selection ◽  
Selection For ◽  
Selection Intensities ◽  
Selection Of ◽  
Better Than

SUMMARYAn experimental evaluation of Robertson's (1970) theory concerning optimum intensities of selection for selection of varying durations has been carried out using published results from a long term selection study in Drosophila. Agreement of predicted rankings of treatments with expectations was excellent for low values of t/T (generations/total number scored) but poor for larger values of t/T. This was due to the 20% selection intensity treatments responding worse than expected and the 40% treatments relatively better than expected. Several possible reasons for the discrepancies exist but the most likely explanation is considered to be the greater reduction in effective population size due to selection in treatments with more intense selection.

Seed traits evaluation from long-term selection of kernel oil concentration in a high-oil maize population KYHO

2012 ◽  
Vol 92 (5) ◽  
pp. 857-866
Author(s):  
Wang Hong-Wu ◽  
Hu Hai-Xiao ◽  
Song Tong-Ming ◽  
Chen Shao-Jiang
Keyword(s):  
Protein Content ◽  
Oil Content ◽  
Selective Breeding ◽  
Starch Content ◽  
Term Selection ◽  
Kernel Oil ◽  
Maize Population ◽  
Oil Concentration ◽  
Selection Of

Wang, H.-W., Hu, H.-X., Song, T.-M. and Chen, S.-J. 2012. Seed traits evaluation from long-term selection of kernel oil concentration in a high-oil maize population KYHO. Can. J. Plant Sci. 92: 857–866. A high-oil maize population, KYHO, was developed over 10 generations by selective breeding for increased kernel oil content (KOC). The objectives of this study were to evaluate kernel oil selection effects, and measure the trait changes and genetic variance in the embryo and endosperm. Oil, protein, and starch content in the embryo and endosperm were estimated by near-infrared reflectance spectroscopy (NIRS). Mass and volume of embryo and endosperm were measured. Selective breeding increased embryo oil content (EMOC) and endosperm oil content (ENOC), especially EMOC, which changed from 315.62 g kg−1C0 to 592.54 g kg−1C10, resulting in an increase in total embryo and endosperm oil content (EEOC) from 43.32 g kg−1C0 to 139.95 g kg−1C10. With selection for increase in EEOC, embryo protein content (EMPC) decreased slightly; however, endosperm protein content (ENPC) and total protein content (EEPC) increased significantly. Embryo and endosperm starch content (EMSC and ENSC) and total starch content (EESC) all decreased substantially with selection. One hundred embryo mass (EMM) was not notably changed with selection, but 100 embryo volume (EMV) increased significantly. Mass and volume of endosperm (ENM and ENV) and total mass and volume of embryo and endosperm (EEM and EEV) all decreased significantly with selection, possibly due to markedly decreased starch content. Linear regression analysis indicated with each 1 g kg−1EEOC increase, EMOC, ENOC, ENPC, EEPC, EMM, and EMV increased 2.74 g kg−1, 0.16 g kg−1, 0.38 g kg−1, 0.36 g kg−1, 0.06 g, and 0.20 mL, respectively, and EMPC, EMSC, ENSC, EESC, EEM, ENM, EEV, and ENV decreased 0.04 g kg−1, 1.48 g kg−1, 0.60 g kg−1, 1.09 g kg−1, 1.26 g, 1.32 g, 0.97 g, and 1.17 mL, rspectively.

scholarly journals The Central Role of PDR1 in the Foundation of Yeast Drug Resistance

2006 ◽  
Vol 282 (7) ◽  
pp. 5063-5074 ◽  
Author(s):  
Vivienne Fardeau ◽  
Gaëlle Lelandais ◽  
Andrew Oldfield ◽  
Hélène Salin ◽  
Sophie Lemoine ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Genetic Determinants ◽  
Term Selection ◽  
Basal Expression ◽  
Drug Dependent ◽  
Dna Binding Properties ◽  
Early Drug ◽  
Selection Of

The widespread pleiotropic drug resistance (PDR) phenomenon is well described as the long term selection of genetic variants expressing constitutively high levels of membrane transporters involved in drug efflux. However, the transcriptional cascades leading to the PDR phenotype in wild-type cells are largely unknown, and the first steps of this phenomenon are poorly understood. We investigated the transcriptional mechanisms underlying the establishment of an efficient PDR response in budding yeast. We show that within a few minutes of drug sensing yeast elicits an effective PDR response, involving tens of PDR genes. This early PDR response (ePDR) is highly dependent on the Pdr1p transcription factor, which is also one of the major genetic determinants of long term PDR acquisition. The activity of Pdr1p in early drug response is not drug-specific, as two chemically unrelated drugs, benomyl and fluphenazine, elicit identical, Pdr1p-dependent, ePDR patterns. Our data also demonstrate that Pdr1p is an original stress response factor, the DNA binding properties of which do not depend on the presence of drugs. Thus, Pdr1p is a promoter-resident regulator involved in both basal expression and rapid drug-dependent induction of PDR genes.

scholarly journals Experimental Evolution of Interference Competition

2021 ◽  
Vol 12 ◽  
Author(s):  
Florien A. Gorter ◽  
Carolina Tabares-Mafla ◽  
Rees Kassen ◽  
Sijmen E. Schoustra
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Experimental Evolution ◽  
Species Interactions ◽  
Interference Competition ◽  
Toxin Production ◽  
Clinical Isolates ◽  
Term Selection ◽  
Selection Of

The importance of interference competition, where individuals compete through antagonistic traits such as the production of toxins, has long been recognized by ecologists, yet understanding how these types of interactions evolve remains limited. Toxin production is thought to be beneficial when competing with a competitor. Here, we explore if antagonism can evolve by long-term selection of the toxin (pyocin) producing strain Pseudomonas aeruginosa PAO1 in the presence (or absence) of one of three clinical isolates of the same species (Recipient) over ten serial transfers. We find that inhibition decreases in the absence of a recipient. In the presence of a recipient, antagonism evolved to be different depending on the recipient used. Our study shows that the evolution of interference competition by toxins can decrease or increase, experimentally demonstrating the importance of this type of interaction for the evolution of species interactions.

scholarly journals Using genetic Potential of Teosinte from Collection of N.I.Vavilov Research Institute of Plant Industry to Expand Polymorphism of Prolific Maize (Zea mays L.)

2019 ◽  
Author(s):  
E B Khatefov ◽  
S P Appaev
Keyword(s):  
Zea Mays ◽  
Lower Layer ◽  
Genetic Erosion ◽  
Hybrid Plant ◽  
Hybrid Progeny ◽  
Term Selection ◽  
Soil Preparation ◽  
Its Polymorphism ◽  
Selection Of

A threat of genetic erosion of maize stimulate search for new sources to extend its polymorphism. Teosinte (Zea mays ssp. mexicana), being wild relative of maize, is easily intercrossed with maize and is characterized with a large potential of variability with respect to economically viable attributes, among them being prolific that is having more than one ear. Results are given of long-term selection of maize lines for the attribute of being prolific among the progeny of a hybrid between teosinte (int-350969) and maize. Selection was conducted against the background of soil preparation ideal for maize in a number of attributes that are congruent with prolificacy and synchronous blooming of all or at least majority of ears on a stalk. A wide diversity in the prolificacy of maize was obtained, with the prolificacy coefficient of up to kpr = 3.3 with a complicated mode of inheritance in hybrid progeny. Results of topcrossing with a single-ear sterile tester showed a specific reaction of the lines, provisionally dividing them into 4 groups by the nature of manifestation of the prolificacy in the hybrid progeny. It has been established that the prolific lines, which in hybridization with the single-ear tester are capable of forming more than one ear in the hybrid plant are of higher selective value. At that, it is important to take into account simultaneity of blooming of all the ears at a male plant. Observation of this principle leads to preservation of structure and evenness of ears in upper and lower layer, thus providing their productivity independent of layer on the stalk. Valuable prolific lines have been established for creation of prolific maize hybrids.

scholarly journals 277 Phenotypic and genetic differences in Rambouillet lines divergently selected for reproductive rate over 50 years

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 206-206
Author(s):  
Tom Murphy ◽  
Jennifer M Thomson ◽  
James Berardinelli ◽  
Brent Roeder
Keyword(s):  
Genetic Correlations ◽  
Phenotypic Selection ◽  
Reproductive Rate ◽  
Breeding Value ◽  
Control Line ◽  
Selection Experiment ◽  
Term Selection ◽  
Selection For ◽  
Fleece Weight

Abstract A long-term selection experiment was conducted in a Rambouillet flock from 1969 to 2017. The high (HL) and low lines (LL) were divergently selected based on a maternal reproductive index, and an unselected control line (CL) was also maintained. Adult ewe traits considered were NLB, greasy fleece weight (GFW), and body weight after fall weaning of their lambs (BW). Results indicated that NLB was greatest for HL (1.67 ± 0.01), intermediate for CL (1.48 ± 0.02), and least for LL (1.28 ± 0.01; P < 0.001). Ewe GFW was greatest for LL (3.9 ± 0.02 kg; P ≤ 0.01) but not different between HL (3.82 ± 0.02 kg) and CL (3.88 ± 0.02 kg; P = 0.08); whereas, BW was least for HL (61.7 ± 0.19 kg; P ≤ 0.01) and not different between LL (62.9 ± 0.21 kg) and CL (62.6 ± 0.25 kg; P = 0.58). Heritability was estimated to be low for NLB (0.13 ± 0.02) and moderate for GFW (0.55 ± 0.03) and BW (0.46 ± 0.04). Genetic correlations were estimated to be near zero between NLB and GFW (-0.07 ± 0.08) and NLB and BW (0.12 ± 0.08) and low between GFW and BW (0.29 ± 0.06). Trends for NLB predicted breeding value differed among all 3 lines (P < 0.01) and was positive for HL (0.012 ± 0.0002 lambs/birth year), negative for LL (-0.005 ± 0.0002), and small but positive for CL (0.002 ± 0.0002). Inbreeding rates were positive in all lines but greatest for HL (0.45 ± 0.005 %/birth year), intermediate in LL (0.37 ± 0.006), and lowest in CL (0.28 ± 0.006). Results indicated long-term phenotypic selection for reproductive rate was effective and not genetically antagonistic with wool production or mature BW.

scholarly journals Modern technologies of robotized cowing milk

2019 ◽  
pp. 54-57
Author(s):  
L. Yu. Kiselev ◽  
R. A. Kamalov ◽  
M. Yu. Borisov ◽  
N. A. Fedoseeva ◽  
Z. S. Sanova
Keyword(s):  
Milk Yield ◽  
Minimum Distance ◽  
Term Selection ◽  
Milk Flow ◽  
Angle Of Deviation ◽  
Kaluga Region ◽  
Robotic Milking ◽  
Modern Technologies ◽  
Selection Of

The studies were conducted in the conditions of LLC “Milk Group” of Sukhinichsky district of Kaluga region. The object of research is robotic milking machines, Swedish breed cows and Danish red breeds. Equality of development of the front and rear lobes, the udder index, the average milk flow rate and the frequency of delivery can be achieved only with long-term selection by type, good severity of signs of milkiness. Based on the selection of cows for milking on a robotized milking plant, the following requirements were put forward: high milk productivity and milk yield, tightly attached udder, nipples of the same size, the lower point of which should not be below 33 cm from the floor level, the minimum distance between the rear nipples in 3 cm, between the front nipples - 12.5 - 30 cm, the thickness of the nipples in the range of 1.5-3.5 cm, the rear nipples should be located 3 cm lower than the lower part of the udder, the minimum distance between the front and rear These udder teats - 7 cm, an angle of deviation from vertical teats should not exceed 30 °. The main reasons for the insignificant loss of milk during robotic milking are the milking of cows that do not have a full-fledged milk-giving reflex or the reflex was inhibited at the beginning of the milking of milk with a delay in putting the teat on the teats of the udder. The size of one-time milk yield, with the exception of the program indicators of this restriction on the milk yield, is determined by the frequency of effective visits to the robot (i.e., the multiplicity of milking during the day). In robotic milking, the frequency of milkings varies by day periods relatively little and drops to a minimum only in the second half of the night, in our opinion, due to the relatively late distribution of feed mixtures. It is also noted that cows of all ages have the same number of milkings on a robotized unit within 2 times.

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