scholarly journals The rate of selection advance for non-additive loci

1969 ◽  
Vol 13 (2) ◽  
pp. 165-173 ◽  
Author(s):  
W. G. Hill
Keyword(s):  
Inbreeding Depression ◽  
Quantitative Trait ◽  
Half Life ◽  
Gene Frequency ◽  
Gene Action ◽  
Dominant Gene ◽  
Single Locus ◽  
Dominant Allele ◽  
Total Change ◽  
The Mean

Expected changes in the gene frequency and the population mean for a quantitative trait are described for selection in a population of size N at a single locus where the favoured allele has initial frequency q0 and selective value s. Models of additive and completely dominant gene action are compared. Results are generally expressed as the half-life of the total change relative to N.If the favoured allele is additive or recessive the half-life of the gene frequency and mean of the trait are usually reduced when q0 or Ns is increased. However, if the dominant allele is favoured the half-life of gene frequency is still generally reduced as Ns is increased, but has a minimum at low or intermediate values of q0. Since inbreeding depression and selection oppose each other when the dominant allele is favoured the response in the mean of the quantitative trait may change in direction during selection.

scholarly journals Selection responses of means and inbreeding depression for female fecundity in Drosophila melanogaster suggest contributions from intermediate-frequency alleles to quantitative trait variation

2007 ◽  
Vol 89 (2) ◽  
pp. 85-91 ◽  
Author(s):  
BRIAN CHARLESWORTH ◽  
TAKAHIRO MIYO ◽  
HELEN BORTHWICK
Keyword(s):  
Drosophila Melanogaster ◽  
Inbreeding Depression ◽  
Quantitative Trait ◽  
Balancing Selection ◽  
Evolutionary Genetics ◽  
Intermediate Frequency ◽  
Female Fecundity ◽  
Deleterious Alleles ◽  
The Mean ◽  
Change In Mean

SummaryThe extent to which quantitative trait variability is caused by rare alleles maintained by mutation, versus intermediate-frequency alleles maintained by balancing selection, is an unsolved problem of evolutionary genetics. We describe the results of an experiment to examine the effects of selection on the mean and extent of inbreeding depression for early female fecundity in Drosophila melanogaster. Theory predicts that rare, partially recessive deleterious alleles should cause a much larger change in the effect of inbreeding than in the mean of the outbred population, with the change in inbreeding effect having an opposite sign to the change in mean. The present experiment fails to support this prediction, suggesting that intermediate-frequency alleles contribute substantially to genetic variation in early fecundity.

Plasma Thrombospondin as an Indicator of Intravascular Platelet Activation in Patients with Vasculitis

1987 ◽  
Vol 58 (03) ◽  
pp. 850-852 ◽  
Author(s):  
M B McCrohan ◽  
S W Huang ◽  
J W Sleasman ◽  
P A Klein ◽  
K J Kao
Keyword(s):  
Platelet Activation ◽  
Plasma Levels ◽  
Half Life ◽  
Degradation Products ◽  
Plasma Concentrations ◽  
Primary Source ◽  
Positive Correlation ◽  
Activation Marker ◽  
Fibrin Degradation Products ◽  
The Mean

SummaryThe use of plasma thrombospondin (TSP) concentration was investigated as an indicator of intravascular platelet activation. Patients (n = 20) with diseases that have known vasculitis were included in the study. The range and the mean of plasma TSP concentrations of patients with vasculitis were 117 ng/ml to 6500 ng/ml and 791±1412 ng/ml (mean ± SD); the range and the mean of plasma TSP concentrations of control individuals (n = 33) were 13 ng/ml to 137 ng/ml and 59±29 ng/ml. When plasma TSP concentrations were correlated with plasma concentrations of another platelet activation marker, β-thromboglobulin (P-TG), it was found that the TSP concentration inei eased exponentially as the plasma β-TG level rose. A positive correlation between plasma levels of plasma TSP and serum fibrin degradation products was also observed. The results suggest that platelets are the primary source of plasma TSP in patients with various vasculitis and that plasma TSP can be a better indicator than β-TG to assess intravascular platelet activation due to its longer circulation half life.

Multiplicative vs. arbitrary gene action in heterosis.

Genetics ◽  
1992 ◽  
Vol 131 (2) ◽  
pp. 461-469 ◽  
Author(s):  
F W Schnell ◽  
C C Cockerham
Keyword(s):  
Gene Action ◽  
Extensive Literature ◽  
Additive Effects ◽  
Nonlinear Functions ◽  
Epistatic Effects ◽  
Genetic Significance ◽  
The Mean ◽  
The Difference ◽  
Multiplicative Models ◽  
Multiplicative Effects

Abstract In this article we investigate multiplicative effects between genes in relation to heterosis. The extensive literature on heterosis due to multiplicative effects between characters is reviewed, as is earlier work on the genetic description of heterosis. A two-locus diallelic model of arbitrary gene action is used to derive linear parameters for two multiplicative models. With multiplicative action between loci, epistatic effects are nonlinear functions of one-locus effects and the mean. With completely multiplicative action, the mean and additive effects form similar restrictions for all the rest of the effects. Extensions to more than two loci are indicated. The linear parameters of various models are then used to describe heterosis, which is taken as the difference between respective averages of a cross (F1) and its two parent populations (P). The difference (F2 - P) is also discussed. Two parts of heterosis are distinguished: part I arising from dominance, and part II due to additive x additive (a x a)-epistasis. Heterosis with multiplicative action between loci implies multiplicative accumulation of heterosis present at individual loci in part I, in addition to multiplicative (a x a)-interaction in part II. Heterosis with completely multiplicative action can only be negative (i.e., the F1 values must be less than the midparent), but the difference (F2 - P) can be positive under certain conditions. Heterosis without dominance can arise from multiplicative as well as any other nonadditive action between loci, as is exemplified by diminishing return interaction. The discussion enlarges the scope in various directions: the genetic significance of multiplicative models is considered.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals A comparison of two methods for predicting changes in the distribution of gene frequency when selection is applied repeatedly to a finite population

1969 ◽  
Vol 13 (2) ◽  
pp. 117-126 ◽  
Author(s):  
Derek J. Pike
Keyword(s):  
Iterative Procedure ◽  
Gene Frequency ◽  
Finite Population ◽  
Transition Matrices ◽  
Single Cycle ◽  
Gene Frequencies ◽  
Mean And Variance ◽  
The Mean ◽  
The One ◽  
Selection Of

Robertson (1960) used probability transition matrices to estimate changes in gene frequency when sampling and selection are applied to a finite population. Curnow & Baker (1968) used Kojima's (1961) approximate formulae for the mean and variance of the change in gene frequency from a single cycle of selection applied to a finite population to develop an iterative procedure for studying the effects of repeated cycles of selection and regeneration. To do this they assumed a beta distribution for the unfixed gene frequencies at each generation.These two methods are discussed and a result used in Kojima's paper is proved. A number of sets of calculations are carried out using both methods and the results are compared to assess the accuracy of Curnow & Baker's method in relation to Robertson's approach.It is found that the one real fault in the Curnow-Baker method is its tendency to fix too high a proportion of the genes, particularly when the initial gene frequency is near to a fixation point. This fault is largely overcome when more individuals are selected. For selection of eight or more individuals the Curnow-Baker method is very accurate and appreciably faster than the transition matrix method.

scholarly journals The mutation load under tetrasomic inheritance and its consequences for the evolution of the selfing rate in autotetraploid species

1999 ◽  
Vol 74 (1) ◽  
pp. 31-42 ◽  
Author(s):  
J. RONFORT
Keyword(s):  
Inbreeding Depression ◽  
Deleterious Mutation ◽  
Stable State ◽  
Approximate Solutions ◽  
Balance Model ◽  
Deleterious Mutations ◽  
Selfing Rate ◽  
Mutation Load ◽  
Mean Fitness ◽  
The Mean

Single-locus equilibrium frequencies of a partially recessive deleterious mutation under the mutation–selection balance model are derived for partially selfing autotetraploid populations. Assuming multiplicative fitness interactions among loci, approximate solutions for the mean fitness and inbreeding depression values are also derived for the multiple locus case and compared with expectations for the diploid model. As in diploids, purging of deleterious mutations through consanguineous matings occurs in autotetraploid populations, i.e. the equilibrium mutation load is a decreasing function of the selfing rate. However, the variation of inbreeding depression with the selfing rate depends strongly on the dominance coefficients associated with the three heterozygous genotypes. Inbreeding depression can either increase or decrease with the selfing rate, and does not always vary monotonically. Expected issues for the evolution of the selfing rate consequently differ depending on the dominance coefficients. In some cases, expectations for the evolution of the selfing rate resemble expectations in diploids; but particular sets of dominance coefficients can be found that lead to either complete selfing or intermediate selfing rates as unique evolutionary stable state.

scholarly journals Selection, Load and Inbreeding Depression in a Large Metapopulation

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1191-1202 ◽  
Author(s):  
Michael C Whitlock
Keyword(s):  
Population Structure ◽  
Inbreeding Depression ◽  
Population Subdivision ◽  
Response To Selection ◽  
Mutation Load ◽  
Deleterious Alleles ◽  
Subdivided Population ◽  
Soft Selection ◽  
Mean Fitness ◽  
The Mean

Abstract The subdivision of a species into local populations causes its response to selection to change, even if selection is uniform across space. Population structure increases the frequency of homozygotes and therefore makes selection on homozygous effects more effective. However, population subdivision can increase the probability of competition among relatives, which may reduce the efficacy of selection. As a result, the response to selection can be either increased or decreased in a subdivided population relative to an undivided one, depending on the dominance coefficient FST and whether selection is hard or soft. Realistic levels of population structure tend to reduce the mean frequency of deleterious alleles. The mutation load tends to be decreased in a subdivided population for recessive alleles, as does the expected inbreeding depression. The magnitude of the effects of population subdivision tends to be greatest in species with hard selection rather than soft selection. Population structure can play an important role in determining the mean fitness of populations at equilibrium between mutation and selection.

scholarly journals INHERITANCE OF FERTILITY RESTORATION INVOLVING WILD ABORTIVE CYTOPLASMIC MALE STERILITY SYSTEM IN RICE (Oryza sativa L.)

2011 ◽  
Vol 24 (1) ◽  
pp. 33-40
Author(s):  
M. J. Hasan ◽  
M. U. Kulsum ◽  
A. Ansari ◽  
A. K. Paul ◽  
P. L. Biswas
Keyword(s):  
Oryza Sativa ◽  
Cytoplasmic Male Sterility ◽  
Male Sterility ◽  
Gene Action ◽  
Oryza Sativa L ◽  
Fertility Restoration ◽  
Dominant Gene ◽  
Recessive Gene ◽  
Male Sterile ◽  
Male Sterile Line

Inheritance of fertility restoration was studied in crosses involving ten elite restorer lines of rice viz. BR6839-41-5-1R, BR7013-62-1-1R, BR7011-37-1-2R, BR10R, BR11R, BR12R, BR13R, BR14R, BR15R and BR16R and one male sterile line Jin23A with WA sources of cytoplasmic male sterility. The segregation pattern for pollen fertility of F2 and BC1 populations of crosses involving Jin23A indicated the presence of two independent dominant fertility restoring genes. The mode of action of the two genes varied in different crosses revealing three types of interaction, i.e. epistasis with dominant gene action, epistasis with recessive gene action, and epistasis with incomplete dominance.DOI: http://dx.doi.org/10.3329/bjpbg.v24i1.16997

Impairment of Antipyrine Metabolism in Urinary Tract Cancer

1983 ◽  
Vol 69 (3) ◽  
pp. 221-222 ◽  
Author(s):  
Maura Ludovici ◽  
Piero Dolara ◽  
Alfiero Costantini ◽  
Guido Barbagli ◽  
Anna Calzolai ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Half Life ◽  
Clinical Parameters ◽  
Tract Cancer ◽  
Patients With Cancer ◽  
Control Subjects ◽  
Antipyrine Metabolism ◽  
Urinary Tract Cancer ◽  
The Mean ◽  
Age And Sex

The metabolism of antipyrine was studied in 13 patients with cancer and bladder papillomas and in 11 control subjects, matched for interfering factors like smoking, diet, age and sex. The mean antipyrine half-life was significantly longer in patients with urinary tract cancer (14.7 ± 1.32 h SE) than in control subjects (11 ± 0.55 h SE) (P < 0.025); other clinical parameters did not vary.

A Study of the Metabolism of Fibrinogen after Surgical Operations

1971 ◽  
Vol 41 (2) ◽  
pp. 141-152 ◽  
Author(s):  
J. A. Hickman
Keyword(s):  
Venous Thrombosis ◽  
Disseminated Intravascular Coagulation ◽  
Half Life ◽  
Plasma Fibrinogen ◽  
Intravascular Coagulation ◽  
Plasma Loss ◽  
The Mean ◽  
Chronic Disorders ◽  
Contrast Group ◽  
Surgical Operations

1. The turnover of fibrinogen was studied in twenty-eight patients after moderate and major surgical operations and in a contrast group of thirteen patients suffering from miscellaneous chronic disorders. 2. After operation the mean biological half-life of fibrinogen was 60.1 h (SD 16.4) and the mean plasma loss of fibrinogen was 40.1% (SD 12.6) of the intravascular fibrinogen pool each 24 h. In the contrast group, respective values of 96.2 h (SD 13.1) and 22.5% (SD 2.0) were obtained, which are in agreement with published values for the normal catabolism of fibrinogen. 3. When the post-operative increase in the plasma fibrinogen pool was taken into account, a massive increase in the absolute plasma loss of fibrinogen was observed with values approaching those reported for albumin turnover. 4. Possible sites of loss and the relevance of this investigation to the detection of disseminated intravascular coagulation and venous thrombosis are discussed.

scholarly journals Heterosis in the second and third generation affects litter size in a crossbreed mink (Neovison vison) population

2014 ◽  
Vol 66 (3) ◽  
pp. 1097-1103 ◽  
Author(s):  
Janne Thirstrup ◽  
Cino Pertoldi ◽  
Peter Larsen ◽  
Vivi Nielsen
Keyword(s):  
Litter Size ◽  
Maternal Effects ◽  
Inbreeding Depression ◽  
Neovison Vison ◽  
Parental Line ◽  
Third Generation ◽  
Black Line ◽  
Environmental Variations ◽  
The Mean ◽  
One Year

Litter sizes in a cross between Brown and Black mink color types were observed through six generations. Litter size was significantly affected by yearly environmental variations. After adjusting for year effects, we found significant increases in litter size in the second and third generations (F2 and F3) after crossing. Thereafter, in the following generations, litter size dropped to a level comparable to the mean litter size of the midparent. Increased litter size in F2 compared to F1 indicated that maternal effects influenced litter size more than non-maternal effects. The heterosis was mainly caused by an increase in litter size compared to the Black parental line. This indicates that the Black line was affected by inbreeding depression prior to crossing. We also found that two-year old F1 females had significantly more offspring compared to one-year old F1 females.

Sign in / Sign up

Export Citation Format

Share Document