scholarly journals Further Properties of Gavrilets’ One-Locus Two-Allele Model of Maternal Selection

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1689-1692
Author(s):  
Hamish G Spencer
Keyword(s):  
Maternal Effects ◽  
Viability Selection ◽  
Diallelic Locus ◽  
Genotype Frequencies ◽  
Special Case ◽  
Allele Model

Abstract I derive several properties of the model proposed by Gavrilets for maternal selection at a single diallelic locus. Most notably, (i) stable oscillations of genotype frequencies (i.e., cycling) can occur and (ii) in the special case in which maternal effects and standard viability selection act multiplicatively, maternal selection effectively acts on maternally derived alleles only.

scholarly journals DEVIATIONS OF GENOTYPIC STRUCTURES FROM HARDY-WEINBERG PROPORTIONS UNDER RANDOM MATING AND DIFFERENTIAL SELECTION BETWEEN THE SEXES

Genetics ◽  
1981 ◽  
Vol 98 (1) ◽  
pp. 215-230
Author(s):  
Martin Ziehe ◽  
Hans-Rolf Gregorius
Keyword(s):  
Population Genetic ◽  
Random Mating ◽  
Genetic Models ◽  
Selection Intensity ◽  
Differential Selection ◽  
Viability Selection ◽  
Strong Affinity ◽  
Genotype Frequencies ◽  
Two Generations ◽  
Differential Viability

ABSTRACT Population genetic models, such as differential viability selection between the sexes and differential multiplicative fecundity contributions of the sexes, are considered for a single multiallelic locus. These selection models usually produce deviations of the zygotic genotype frequencies from Hardy-Weinberg proportions. The deviations are investigated (with special emphasis put on equilibrium states) to quantify the effect of selective asymmetry in the two sexes. For many selection regimes, the present results demonstrate a strong affinity of zygotic genotype frequencies for Hardy-Weinberg proportions after two generations, at the latest. It is shown that the deviations of genotypic equilibria from the corresponding Hardy-Weinberg proportions can be expressed and estimated by means of selection components of only that sex with the lower selection intensity. This corresponds to the well-known fact that viability selection acting in only one sex yields Hardy-Weinberg equilibria.

scholarly journals Deviations from Hardy–Weinberg proportions for multiple alleles under viability selection

2008 ◽  
Vol 90 (2) ◽  
pp. 209-216 ◽  
Author(s):  
GONZALO ALVAREZ
Keyword(s):  
Stable Equilibrium ◽  
Random Mating ◽  
Published Data ◽  
Human Populations ◽  
Autosomal Locus ◽  
Allele Polymorphism ◽  
Multiple Alleles ◽  
Viability Selection ◽  
Genotype Frequencies ◽  
Fixation Indices

SummaryDepartures of genotype frequencies from Hardy–Weinberg proportions (HWP) for a single autosomal locus due to viability selection in a random mating population have been studied only for the two-allele case. In this article, the analysis of deviations from HWP due to constant viability selection is extended to multiple alleles. The deviations for an autosomal locus with k alleles are measured by means of k fii fixation indices for homozygotes and k(k−1)/2 fij fixation indices for heterozygotes, and expressions are obtained for these indices (FIS statistics) under the multiallele viability model. Furthermore, expressions for fii and fij when the multiallele polymorphism is at stable equilibrium are also derived and it is demonstrated that the pattern of multiallele Hardy–Weinberg deviations at equilibrium is characterized by a global heterozygote excess and a deficiency of each of the homozygotes. This pattern may be useful for detecting whether a given multiallelic polymorphism is at stable equilibrium in the population due to viability selection. An analysis of Hardy–Weinberg deviations from published data for the three-allele polymorphism at the β-globin locus in human populations from West Africa is presented for illustration.

scholarly journals Nonlinear maternal effects on personality in a rodent species with fluctuating densities

2020 ◽  
Author(s):  
Bram Vanden Broecke ◽  
Aurelia Bongers ◽  
Ladslaus Mnyone ◽  
Erik Matthysen ◽  
Herwig Leirs
Keyword(s):  
Maternal Effects ◽  
Animal Personality ◽  
Parental Effects ◽  
Wild Populations ◽  
Linear Pattern ◽  
Maternal Personality ◽  
Large Fluctuations ◽  
Exploration Behavior ◽  
Genetic And Environmental Factors ◽  
Special Case

Abstract Consistent among-individual variation in behavior, or animal personality, is present in a wide variety of species. This behavioral variation is maintained by both genetic and environmental factors. Parental effects are a special case of environmental variation and are expected to evolve in populations experiencing large fluctuations in their environment. They represent a non-genetic pathway by which parents can transmit information to their offspring, by modulating their personality. While it is expected that parental effects contribute to the observed personality variation, this has rarely been studied in wild populations. We used the multimammate mouse Mastomys natalensis as a model system to investigate the potential effects of maternal personality on offspring behavior. We did this by repeatedly recording the behavior of individually housed juveniles which were born and raised in the lab from wild caught females. A linear correlation, between mother and offspring in behavior, would be expected when the personality is only affected by additive genetic variation, while a more complex relationship would suggests the presence of maternal effects. We found that the personality of the mother predicted the behavior of their offspring in a non-linear pattern. Exploration behavior of mother and offspring was positively correlated, but only for slow and average exploring mothers, while this correlation became negative for fast exploring mothers. This may suggests that early maternal effects could affect personality in juvenile M. natalensis, potentially due to density-dependent and negative frequency-dependent mechanisms, and therefore contribute to the maintenance of personality variation.

Genetic Diversity at a Single Locus Under Viability Selection and Facultative Apomixis: Equilibrium Structure and Deviations from Hardy-Weinberg Frequencies

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 2029-2039
Author(s):  
R Deborah Overath ◽  
Marjorie A Asmussen
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Equilibrium Structure ◽  
Single Locus ◽  
Numerical Analyses ◽  
Mixed Mating ◽  
Viability Selection ◽  
Diallelic Locus ◽  
Facultative Apomixis ◽  
Fixation Indices

Abstract We extensively analyze the maintenance of genetic variation and deviations from Hardy-Weinberg frequencies at a diallelic locus under mixed mating with apomixis and constant viability selection. Analytical proofs show that: (1) at most one polymorphic equilibrium exists, (2) polymorphism requires overdominant or underdominant selection, and (3) a simple, modified overdominance condition is sufficient to maintain genetic variation. In numerical analyses, only overdominant polymorphic equilibria are stable, and these are stable whenever they exist, which happens for ~78% of random fitness and mating parameters. The potential for maintaining both alleles increases with increasing apomixis or outcrossing and decreasing selfing. Simulations also indicate that equilibrium levels of heterozygosity will often be statistically indistinguishable from Hardy-Weinberg frequencies and that adults, not seeds, should usually be censused to maximize detecting deviations. Furthermore, although both censuses more often have an excess rather than a deficit of heterozygotes, analytical sign analyses of the fixation indices prove that, overall, adults are more likely to have an excess and seeds a deficit at equilibrium.

scholarly journals SELECTION IN PLANT POPULATIONS OF EFFECTIVELY INFINITE SIZE. V. BIALLELIC MODELS OF TRIOECY

Genetics ◽  
1983 ◽  
Vol 103 (3) ◽  
pp. 529-544
Author(s):  
H R Gregorius ◽  
M D Ross ◽  
E M Gillet
Keyword(s):  
Present Model ◽  
Selfing Rate ◽  
Stable Strategy ◽  
Plant Populations ◽  
Genotype Frequencies ◽  
Males And Females ◽  
Evolution Of Dioecy ◽  
Allele Model ◽  
Mode A ◽  
Male Heterogamety

ABSTRACT A one-locus two-allele model of trioecy (presence of hermaphrodites, males and females in one population) is considered, in order to study the conditions for the persistence of this system. All possible assignments of the three sex types to the three genotypes are considered. This leads to three different modes of inheritance of trioecy, namely (a) females heterozygous, (b) males heterozygous and (c) hermaphrodites heterozygous, where in each mode each of the remaining two sex types is homozygous for one of the alleles. For mode (c) trioecy is always persistent, and the dependence of the sex ratio (for the three sex types) on the ovule and pollen fertilities and on the hermaphrodite selfing rate is specified. For the other two modes, (a) and (b), trioecy is not protected, i.e., it may not persist for any fertilities, viabilities or selfing rates. Thus, in this situation it is important to study the conditions under which the "marginal" systems of sexuality of trioecy, i.e., hermaphroditism, dioecy and gynodioecy in mode (a), and hermaphroditism, dioecy and androdioecy in mode (b), may become established. The results show that each marginal system may evolve from each other via trioecy. The evolution of dioecy is easier in mode (a) than in (b), so that female heterogamety would be expected to occur more often than male heterogamety in the present model. Under some conditions the breeding system obtained in equilibrium populations may depend on the initial genotype frequencies.—The necessity of considering modes of inheritance for sexual polymorphisms is demonstrated by comparing our results with those obtained from an evolutionary stable strategy (ESS) analysis of a purely phenotypic model.

Extreme self-sacrifice beyond fusion: Moral expansiveness and the special case of allyship

2018 ◽  
Vol 41 ◽  
Author(s):  
Daniel Crimston ◽  
Matthew J. Hornsey
Keyword(s):  
General Theory ◽  
Biological Markers ◽  
Natural Environment ◽  
Relevant Dimension ◽  
Special Case

AbstractAs a general theory of extreme self-sacrifice, Whitehouse's article misses one relevant dimension: people's willingness to fight and die in support of entities not bound by biological markers or ancestral kinship (allyship). We discuss research on moral expansiveness, which highlights individuals’ capacity to self-sacrifice for targets that lie outside traditional in-group markers, including racial out-groups, animals, and the natural environment.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Test Validation Without Measurement

2016 ◽  
Vol 32 (3) ◽  
pp. 204-214 ◽  
Author(s):  
Emilie Lacot ◽  
Mohammad H. Afzali ◽  
Stéphane Vautier
Keyword(s):  
Test Data ◽  
Test Scores ◽  
Scientific Explanation ◽  
Test Validation ◽  
Clinical Tests ◽  
Ethical Perspective ◽  
Power Of Test ◽  
Memory Accuracy ◽  
Social Uses ◽  
Special Case

Abstract. Test validation based on usual statistical analyses is paradoxical, as, from a falsificationist perspective, they do not test that test data are ordinal measurements, and, from the ethical perspective, they do not justify the use of test scores. This paper (i) proposes some basic definitions, where measurement is a special case of scientific explanation; starting from the examples of memory accuracy and suicidality as scored by two widely used clinical tests/questionnaires. Moreover, it shows (ii) how to elicit the logic of the observable test events underlying the test scores, and (iii) how the measurability of the target theoretical quantities – memory accuracy and suicidality – can and should be tested at the respondent scale as opposed to the scale of aggregates of respondents. (iv) Criterion-related validity is revisited to stress that invoking the explanative power of test data should draw attention on counterexamples instead of statistical summarization. (v) Finally, it is argued that the justification of the use of test scores in specific settings should be part of the test validation task, because, as tests specialists, psychologists are responsible for proposing their tests for social uses.

Sign in / Sign up

Export Citation Format

Share Document