scholarly journals Natural Selection and the Maintenance of Colour Pattern Polymorphism in the Australian Plague Locust Chortoicetes terminifera

1983 ◽  
Vol 36 (4) ◽  
pp. 387 ◽  
Author(s):  
John M Dearn ◽  
Richard AH Davies
Keyword(s):  
Natural Selection ◽  
Random Mating ◽  
Colour Pattern ◽  
Differential Selection ◽  
Genotype Frequencies ◽  
Eastern Australia ◽  
Males And Females ◽  
Pattern Polymorphism ◽  
Australian Plague Locust ◽  
Dominant Genes

Twelve samples of C. termini/era from seven locations in eastern Australia were analysed for colour pattern polymorphism. Although there was heterogeneity between the samples the overall frequencies of the colour pattern genotypes were very similar. Males and females showed consistent differences in their genotype frequencies and this is presumed to reflect differential selection between the two sexes. A comparison between observed genotype frequencies and those expected under random mating and in the absence of selection revealed large differences. In particular, genotypes heterozygous for two dominant genes were consistently underrepresented. While these differences could result from non-random mating it is argued that they are more likely to be due to viability differences between the genotypes.

Colour Pattern Polymorphism in the Grasshopper Phaulacridium Vittatum. I. Geographic Variation in Victoria and Evidence of Habitat Association.

1984 ◽  
Vol 32 (2) ◽  
pp. 239 ◽  
Author(s):  
JM Dearn
Keyword(s):  
Geographic Variation ◽  
Habitat Associations ◽  
Colour Pattern ◽  
Habitat Association ◽  
Latitudinal Cline ◽  
Selective Constraints ◽  
South Eastern ◽  
Eastern Australia ◽  
Pattern Polymorphism ◽  
Forest Habitats

The frequencies of the 3 colour pattern morphs (plain, striped and incomplete-striped) in samples of Phaulacridium vittatum (Sjost). from pasture sites in Victoria, Australia, did not conform to the pattern predicted by the latitudinal cline in morph frequencies previously described in south-eastern Australia. Data from 2 transects across pasture-forest boundaries revealed the existence of habitat associations, with forest habitats having a higher frequency of the plain morph. The proximity of some pasture populations to forests may explain some of the variation in morph frequencies observed among pasture sites. However, the frequency of the striped morph was relatively low in all the populations examined; this suggests that there are strong selective constraints on the frequency of striped individuals.

scholarly journals A test for Hardy-Weinberg equilibrium on the X chromosome for sex-biased admixed populations

2019 ◽  
Author(s):  
Daniel Backenroth ◽  
Shai Carmi
Keyword(s):  
X Chromosome ◽  
Random Mating ◽  
Allele Frequencies ◽  
Ratio Test ◽  
Weinberg Equilibrium ◽  
Genotype Frequencies ◽  
Genome Wide ◽  
Control Step ◽  
Hardy Weinberg Equilibrium ◽  
Males And Females

AbstractGenome-wide scans for deviations from Hardy-Weinberg equilibrium (HWE) are commonly applied to detect genotyping errors. In contrast to the autosomes, genotype frequencies on the X chromosome do not reach HWE within a single generation. Instead, if allele frequencies in males and females initially differ, they oscillate for a few generations towards equilibrium. Several populations world-wide have experienced recent sex-biased admixture, namely, their male and female founders differed in ancestry and thus in allele frequencies. Sex-biased admixture makes testing for HWE difficult on X, because deviations are naturally expected, even under random mating post-admixture and error-free genotyping. In this paper, we develop a likelihood ratio test and a χ2 test that detect deviations from HWE on X while allowing for natural deviations due to sex-biased admixture. We demonstrate by simulations that our tests are powerful for detecting deviations due to non-random mating, while at the same time they do not reject the null under historical sex-biased admixture and random mating thereafter. We also demonstrate that when applied to 1000 Genomes project populations (e.g., as a quality control step), our tests reject fewer SNPs (among those showing frequency differences between the sexes) than other tests.

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 Deviation from Hardy–Weinberg proportions in finite populations

1996 ◽  
Vol 68 (3) ◽  
pp. 249-257 ◽  
Author(s):  
Jinliang Wang
Keyword(s):  
Sampling Error ◽  
Random Mating ◽  
Random Selection ◽  
Stochastic Simulations ◽  
Gene Frequencies ◽  
Dioecious Species ◽  
Male And Female ◽  
Census Size ◽  
Genotype Frequencies ◽  
Gene Frequency Difference

SummaryFor a finite diploid population with no mutation, migration and selection, equations for the deviation of observed genotype frequencies from Hardy–Weinberg proportions are derived in this paper for monoecious species and for autosomal and sex-linked loci in dioecious species. It is shown that the genotype frequency deviation in finite random-mating populations results from the difference between the gene frequencies of male and female gametes, which is determined by two independent causes: the gene frequency difference between male and female parents and the sampling error due to the finite number of offspring. Previous studies have considered only one of the causes and the equations derived by previous authors are applicable only in the special case of random selection. The general equations derived here for both causes incorporate the variances and covariances of family size and thus they reduce to previous equations for random selection. Stochastic simulations are run to check the predictions from different formulae. Non-random mating and variation in census size are considered and the applications of the derived formulae are exemplified.

The sensitivity of Australian animals to 1080 poison. I. Intraspecific variation and factors affecting acute toxicity

1981 ◽  
Vol 8 (2) ◽  
pp. 369 ◽  
Author(s):  
J. C. Mcilroy
Keyword(s):  
Acute Toxicity ◽  
Intraspecific Variation ◽  
Factors Affecting ◽  
Eastern Australia ◽  
Vertebrate Pests ◽  
Breeding Condition ◽  
Different Populations ◽  
Males And Females

The calculated sensitivity (LD50) of a species to 1080 poison (sodium fluoroacetate), used for control of vertebrate pests, is affected by the experimental procedures employed. Variation can be minimized if the most obvious sources are avoided, as described in this paper. Very young mammals and female waterfowl in breeding condition may be more sensitive to 1080 than other members of their populations. No other substantial differences in sensitivity were found between males and females, immatures and adults, or within and between different populations of six species of birds and mammals in eastern Australia.

scholarly journals A SIMULATION STUDY OF TRUNCATION SELECTION FOR A QUANTITATIVE TRAIT OPPOSED BY NATURAL SELECTION

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 989-1000
Author(s):  
Francis Minvielle
Keyword(s):  
Natural Selection ◽  
Artificial Selection ◽  
Random Mating ◽  
Selection Response ◽  
Quantitative Character ◽  
Mass Selection ◽  
Frequency Selection ◽  
Selection Experiments ◽  
Selection For ◽  
Selective Process

ABSTRACT A quantitative character controlled at one locus with two alleles was submitted to artificial (mass) selection and to three modes of opposing natural selection (directional selection, overdominance and underdominance) in a large random-mating population. The selection response and the limits of the selective process were studied by deterministic simulation. The lifetime of the process was generally between 20 and 100 generations and did not appear to depend on the mode of natural selection. However, depending on the values of the parameters (initial gene frequency, selection intensity, ratio of the effect of the gene to the environmental standard deviation, fitness values) the following outcomes of selection were observed: fixation of the allele favored by artificial selection, stable nontrivial equilibrium, unstable equilibrium and loss of the allele favored by artificial selection. Finally, the results of the simulation were compared to the results of selection experiments.

Class I and II HLA antigens and natural selection haplotypes in greek patients males and females with graves' disease

1996 ◽  
Vol 47 (1-2) ◽  
pp. 30
Author(s):  
F. Harsoulis ◽  
K. Adam ◽  
P. Lazidou ◽  
S. Lalanga ◽  
Z. Polymenidis
Keyword(s):  
Natural Selection ◽  
Hla Antigens ◽  
Class I ◽  
Graves Disease ◽  
Males And Females

Life history and reproductive ecology of White's skink, Egernia whitii

2005 ◽  
Vol 53 (6) ◽  
pp. 353 ◽  
Author(s):  
DG Chapple
Keyword(s):  
Life History ◽  
Litter Size ◽  
Reproductive Ecology ◽  
Climatic Conditions ◽  
Colour Pattern ◽  
Offspring Size ◽  
Adult Sex Ratio ◽  
Pattern Polymorphism ◽  
Comparison Of The Results ◽  
Colour Morphs

The life history and reproductive ecology of White’s skink, Egernia whitii, was examined in a population in the Australian Capital Territory using both field and genetic studies. Colour pattern polymorphism was evident within the population, with both patterned and plain-back morphs present. Lizards typically took 3 years to reach sexual maturity, with the size at maturity being ~75 mm snout–vent length (SVL) in both sexes. There was an even overall adult sex ratio, although a slight female-bias was evident in plain-back individuals. Sexual dimorphism was evident, with males having longer and wider heads, and females having larger body size. Females generally bred annually, with mating occurring in September–October and parturition in late January–February, although the litter was produced over several days (2–10 days, mean 4 days). Litter size ranged from one to four (mean of 2.5). There was a significant relationship between maternal SVL and both litter size and relative clutch mass, but these trends were not consistent between colour morphs. An inverse relationship between litter size and offspring size (SVL and mass) was found. Comparison of the results with previous investigations of E. whitii indicates substantial geographic variation in life-history traits that is presumably associated with latitudinal variation in climatic conditions.

Sign in / Sign up

Export Citation Format

Share Document