Valuing DNA marker tested bulls for commercial beef production

2004 ◽  
Vol 55 (8) ◽  
pp. 825 ◽  
Author(s):  
B. J. Wood ◽  
J. H. J. van der Werf ◽  
P. F. Parnell
Keyword(s):  
Gene Flow ◽  
Allele Frequency ◽  
Gene Frequency ◽  
Dna Marker ◽  
Recessive Gene ◽  
Single Recessive Gene ◽  
Beef Herd ◽  
Thyroglobulin Gene ◽  
Commercial Breeder ◽  
Over Time

This paper quantifies the benefits of using a sire genotyped for a single recessive gene in a commercial beef herd. A modified gene-flow method was used to account for changing allele frequency over time. The benefits to a commercial breeder of using a genotyped sire were highest when initial allele frequency was moderate and when the sire was used in a self-replacing herd that had increased allele frequency over time. An example of the thyroglobulin gene affecting marbling in beef cattle was used. The value to a self-replacing herd of a sire homozygous for the favourable allele of the thyroglobulin gene was shown to be up to $338 more than of an ungenotyped sire, in a population where the initial gene frequency was 0.3 and the genotype accounted for 0.5 standard deviations of phenotypic variation.

scholarly journals A Proposed Model for Inheritance of Primocane Fruiting in Tetraploid Erect Blackberry

2000 ◽  
Vol 125 (2) ◽  
pp. 217-221 ◽  
Author(s):  
Jose Lopez-Medina ◽  
James N. Moore ◽  
Ronald W. McNew
Keyword(s):  
Negative Relationship ◽  
Recessive Gene ◽  
Segregation Ratio ◽  
Breeding Strategies ◽  
Single Recessive Gene ◽  
Tetrasomic Inheritance ◽  
Proposed Model ◽  
Inheritance Model ◽  
Diallel Crossing ◽  
Scheme Selection

Inheritance of the primocane-fruiting (PF) characteristic was studied in seedling populations of tetraploid (4x) blackberries (Rubus subgenus Rubus). Four selections (A-1836, A-593, A-830, and A-1680) and two cultivars (`Arapaho' and `Shawnee') were used as parents in a full diallel crossing scheme. Selection A-593 was used as the main source for PF due to its origin (`Brazos' × `Hillquist,' the latter an old PF cultivar). All parents except `Shawnee' have A-593 in their parentage; among the parents, only A-1836 fully expresses PF. Selfing of A-1836 resulted in 100% PF offspring, indicating that A-1836 is homozygous for this trait. Selfing of A-593, A-830, and `Arapaho' produced either a 35:1 or a 20.8:1 FF (floricane or summer-fruiting):PF segregation ratio, fitting a tetrasomic inheritance model under either random chromosome assortment (RCSA) or random chromatid assortment (RCTA), respectively, also suggesting that PF is controlled by a single recessive gene and that the parents are duplex (AAaa) for this trait. Selection A-1680 and `Shawnee' selfed did not produce PF progeny, but when crossed with the nulliplex A-1836, gave a 27:1 FF:PF ratio, indicating RCTA and that they are triplex (AAAa) for PF. According to these research, both gametic outputs (RCSA and RCTA) seem to operate in 4x blackberry. The intensity in expression of PF had a negative relationship with time to harvest, with those seedlings showing the highest PF scores producing a crop in early to mid-August. This knowledge will be helpful in implementing breeding strategies to produce PF blackberry cultivars.

scholarly journals Geographic patterns of human allele frequency variation: a variant-centric perspective

2020 ◽  
Author(s):  
Arjun Biddanda ◽  
Daniel P. Rice ◽  
John Novembre
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Structure ◽  
Allele Frequency ◽  
Human Genetics ◽  
Geographic Region ◽  
Frequency Variation ◽  
Human Genetic Variation ◽  
Alternative Representation ◽  
Geographic Patterns

AbstractA key challenge in human genetics is to describe and understand the distribution of human genetic variation. Often genetic variation is described by showing relationships among populations or individuals, in each case drawing inferences over a large number of variants. Here, we present an alternative representation of human genetic variation that reveals the relative abundance of different allele frequency patterns across populations. This approach allows viewers to easily see several features of human genetic structure: (1) most variants are rare and geographically localized, (2) variants that are common in a single geographic region are more likely to be shared across the globe than to be private to that region, and (3) where two individuals differ, it is most often due to variants that are common globally, regardless of whether the individuals are from the same region or different regions. To guide interpretation of the results, we also apply the visualization to contrasting theoretical scenarios with varying levels of divergence and gene flow. Our variant-centric visualization clarifies the major geographic patterns of human variation and can be used to help correct potential misconceptions about the extent and nature of genetic differentiation among populations.

Adaptation and Natural Selection

2021 ◽  
pp. 125-154
Author(s):  
Áki J. Láruson ◽  
Floyd A. Reed
Keyword(s):  
Natural Selection ◽  
Allele Frequency ◽  
Levels Of Selection ◽  
Frequency Data ◽  
Selection Coefficient ◽  
Frequency Distributions ◽  
Single Allele ◽  
Selection Strength ◽  
The Difference ◽  
Over Time

Here non-random shifts in allele frequencies over time are introduced, as well as how to incorporate varying levels of selection into a model of a single population through time. This chapter highlights the difference between weak and strong selection, the dynamics of single allele versus genotype-level selection, and how selection strength and population size affect allele frequency distributions over time. Finally the inference of the selection coefficient from allele frequency data is discussed, alongside the concepts of overdominance and underdominance.

The inheritance and chromosomal location of a gene for chocolate chaff in durum wheat

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 229-233 ◽  
Author(s):  
C. F. Konzak ◽  
L. R. Joppa
Keyword(s):  
Durum Wheat ◽  
Chromosomal Location ◽  
Triticum Turgidum ◽  
Recessive Gene ◽  
Single Recessive Gene ◽  
Chromosome Substitution ◽  
Substitution Lines ◽  
D Genome ◽  
B Genome ◽  
Aneuploid Chromosome

The durum wheat (Triticum turgidum L. var. durum) cultivar 'Vic' was treated with the chemical mutagen N-methyl-N′-nitrosourea and among the M2 progeny a mutant with "chocolate chaff" (designated cc) was identified. Genetic analyses indicated that chocolate chaff is due to a single recessive gene mutation. The penetrance of the gene for chocolate chaff was environmentally influenced and varied from dark blotches on the glumes to complete coloration of culms as well as spikes. To determine the chromosomal location of the gene, the mutant was crossed with a set of 'Langdon' durum disomic substitution lines in which each of the 14 A- and B-genome chromosomes of durum wheat were replaced by their respective D-genome homoeologues. The segregation of cc was normal in all of the crosses except for those with the 7D(7A) and 7D(7B) lines. Cytogenetic analysis indicated that the gene was located on chromosome 7B, and that chromosome 7D has a gene that prevents the expression of cc when present in one or more copies. It was shown that the 'Langdon' D-genome disomic substitution lines can be used to determine the chromosomal location of genes in tetraploid wheat.Key words: Triticum turgidum, aneuploid, chromosome substitution, monosomic, cytogenetics.

Response of Corn (Zea maysL.) Inbreds and Hybrids to Sulfonylurea Herbicides

Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 508-516 ◽  
Author(s):  
Jerry M. Green ◽  
Jim F. Ulrich
Keyword(s):  
Genetic Analysis ◽  
Safety Margin ◽  
Recessive Gene ◽  
Response Analysis ◽  
Hybrid Seed Production ◽  
Sulfonylurea Herbicides ◽  
Single Recessive Gene ◽  
Organophosphate Insecticide ◽  
Extensive Field ◽  
Varietal Response

Extensive field and greenhouse studies were done to characterize varietal response of three recently commercialized sulfonylurea corn herbicides: nicosulfuron, primisulfuron, and thifensulfuron. Most of the 94 varieties tested were highly tolerant to these herbicides. The 37 inbreds represented all major inbred families now used in hybrid seed production as well as several sensitive experimentals. Twenty-one defined hybrids from these inbreds as well as 36 commercially coded hybrids were also tested. Sensitive inbreds produced tolerant hybrids when crossed with tolerant inbreds. Sensitive hybrids occurred when both parents were sensitive. Genetic analysis of sensitive by tolerant crosses showed that sensitivity is controlled by a single recessive gene. Nicosulfuron had the widest corn safety margin and fewest sensitive varieties. Dose response analysis showed varieties can vary more than 40 000-fold in sensitivity. Only corn varieties with the AHAS-modified XA-17 gene showed any change in enzyme sensitivity. This gene overcame sensitivity to sulfonylureas, even when the organophosphate insecticide terbufos was present. Thus, breeders have three options to eliminate sulfonylurea sensitivity: backcross sensitive inbreds with tolerant, always use at least one tolerant hybrid parent, or use the XA-17 gene.

THE INHERITANCE AND HISTOLOGY OF A CHLOROPHYLL-DEFICIENT CHARACTER IN MEDICAGO SATIVA L.

1961 ◽  
Vol 39 (4) ◽  
pp. 847-853 ◽  
Author(s):  
W. R. Childers ◽  
H. A. McLennan
Keyword(s):  
Recessive Gene ◽  
Single Recessive Gene ◽  
Mesophyll Cells ◽  
Genetic Studies ◽  
Continuous Layer ◽  
Mesophyll Tissue ◽  
Plant Stage ◽  
Chlorophyll Production ◽  
Medicago Sativa L ◽  
Palisade Cells

Further support for tetrasomic inheritance in alfalfa was shown from genetic studies of a chlorophyll-deficient seedling character. The character was determined by a single recessive gene for which the symbol Viridis-1 or v1 is proposed. At the mature-plant stage, low and intermediate classes for chlorophyll production were observed. Histological examination and chlorophyll analyses confirmed this classification. The low-chlorophyll-producing class was characterized by a lack of plastids in the leaf blades although some plastids occurred in mesophyll tissue around the midrib. The intermediate chlorophyll-deficient class was characterized by yellowish-green leaf blades, associated with colorless palisade cells that overlay a single continuous layer of mesophyll cells in which the plastids were well developed.

scholarly journals DYNAMICS OF THE LINKAGE DISEQUILIBRIUM FUNCTION UNDER MODELS OF GENE-FREQUENCY HITCHHIKING

Genetics ◽  
1981 ◽  
Vol 99 (2) ◽  
pp. 337-356
Author(s):  
Marjorie A Asmussen ◽  
Michael T Clegg
Keyword(s):  
Linkage Disequilibrium ◽  
Gene Frequency ◽  
Initial Conditions ◽  
Recombination Fraction ◽  
Qualitative Description ◽  
Selection Intensity ◽  
Gene Frequencies ◽  
Dependent Behavior ◽  
Wide Range ◽  
Over Time

ABSTRACT The dynamic behavior of the linkage disequilibrium (D) between a neutral and a selected locus is analyzed for a variety of deterministic selection models. The time-dependent behavior of D is governed by the gene frequency at the selected locus (p) and by the selection (s) and recombination (r) parameters. Thomson (1977) showed numerically that D may increase under certain initial conditions. We give exact conditions for D to increase in time, which require that the selection intensity exceed the recombination fraction (s > r) and that p be near zero or one. We conclude from this result that gene frequency hitchhiking is most likely to be important when a new favorable mutant enters a population. We also show that, for what can be a wide range of gene frequencies, D will decay at a faster rate than the neutral rate. Consequently, the hitchhiking effect may quickly diminish as the selected gene becomes more common.—The method of analysis allows a complete qualitative description of the dynamics of D as a function of s and r. Two major findings concern the range of gene frequencies at the selected locus for which D either increases over time or decays at a faster rate than under neutrality. For all models considered, the region where D increases (i) first enlarges then shrinks as selection intensifies, and (ii) steadily shrinks as r increases. In contrast, the region of accelerated decay constantly enlarges as the selection intensity increases. This region will either shrink or enlarge as r increases, depending upon the form of selection in force.

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