THE SIGNIFICANCE OF CHROMOSOME ASSOCIATION IN AN ADVANCED POPULATION OF TETRAPLOID RYE

1976 ◽  
Vol 18 (4) ◽  
pp. 601-609 ◽  
Author(s):  
M. Gul Hossain
Keyword(s):  
Chiasma Frequency ◽  
Random Mating ◽  
Inbred Lines ◽  
Chromosome Association ◽  
Meiotic Behavior ◽  
Association Pattern ◽  
Mating Population ◽  
Secale Cereale L ◽  
Quadrivalent Frequency ◽  
Positive Correlations

Chromosome pairing was studied in a population of tetraploid spring rye (Secale cereale L.) 20 years after the chromosomes were doubled. Cytogenetically the population was heterogeneous as revealed by significant differences between plants for chiasma frequency, the proportions of regular MI cells and regular quartets. Compared to early C generations meiotic behavior in the population improved by an increase in quadrivalent frequency, mainly at the expense of trivalents and univalents. However, quadrivalent frequency failed to correlate with all other meiotic features; instead bivalent frequency had significant positive correlations with the features of meiotic regularity including chiasma frequency. Furthermore, the average quadrivalent frequency in the population was considerably less than that of inbred lines. These facts led to the conclusion that disomic association dominated the chromosome association pattern in this random mating population, whereas in inbred materials the chromosome association pattern is predominantly tetrasomic. This was further proved by a test against the theoretically expected chromosome association pattern in a true autotetaploid.

CYTOLOGICAL STUDIES IN ALFALFA POLYPLOIDS

1954 ◽  
Vol 32 (4) ◽  
pp. 531-542 ◽  
Author(s):  
J. M. Armstrong
Keyword(s):  
Chiasma Frequency ◽  
Diploid Species ◽  
Low Frequency ◽  
Morphological Characters ◽  
Tetraploid Species ◽  
Meiotic Behavior ◽  
Meiotic Irregularities ◽  
Medicago Sativa L ◽  
Partial Homology ◽  
Quadrivalent Frequency

Normal tetraploid alfalfa, Medicago sativa L., is characterized by meiotic irregularities consisting of a low percentage of univalents, trivalents, and quadrivalents. While these irregularities might suggest an autoploid origin, their frequency is too low to be conclusive. Cytological studies of the induced octoploid and of the hexaploid, obtained from crossing tetraploid and octoploid, indicate that the two genomes in the tetraploid are only partially homologous. The partial homology is established by the meiotic behavior in the hexaploid in which a low univalent frequency indicates fairly complete pairing between the A and B genomes. The comparatively low frequency of quadrivalents in the octoploid indicates a correspondingly low chiasma frequency at pachytene. Nevertheless this quadrivalent frequency in the octoploid is more than three times as high as in the tetraploid which suggests a lack of complete homology between the two genomes. The theory is advanced that tetraploid species of Medicago originated from crosses between a series of diploid species fairly similar cytologically but differing in well marked, morphological characters. This affords an explanation for the inheritance of some characters in a disomic and others in a tetrasomic manner. Cytological and genetic evidence thus points to tetraploid alfalfa as originating as an alloploid from closely related diploid species.

GENETIC CONTROL OF CHIASMA FREQUENCY AND DISTRIBUTION IN RYE SECALE CEREALE

1978 ◽  
Vol 20 (4) ◽  
pp. 471-474 ◽  
Author(s):  
T. Lelley
Keyword(s):  
Control System ◽  
Negative Correlation ◽  
Secale Cereale ◽  
Chiasma Frequency ◽  
Positional Distribution ◽  
Direct Consequence ◽  
Inbred Lines ◽  
Secale Cereale L ◽  
The Mean ◽  
Cell Variance

In inbred lines of rye (Secale cereale L.) a close negative correlation was found between mean chiasma number and their between-cell variance. No correlation was detected between mean chiasma number or chiasma variance and the positional distribution of chiasmata within the bivalents, that is, terminal or interstitial. It is concluded, therefore, that while the between-cell variance of chiasmata is a direct consequence of the mean chiasma frequency, the positional distribution of chiasmata within bivalents is probably subject to an independent control system.

scholarly journals Average Number of Nucleotide Differences in a Sample From a Single Subpopulation: A Test for Population Subdivision

Genetics ◽  
1987 ◽  
Vol 117 (1) ◽  
pp. 149-153
Author(s):  
Curtis Strobeck
Keyword(s):  
Monte Carlo Simulation ◽  
Population Structure ◽  
Random Mating ◽  
Population Subdivision ◽  
Expected Number ◽  
Migration Rates ◽  
Mating Population ◽  
Unbiased Estimates ◽  
Increasing Function ◽  
Stepping Stone Model

ABSTRACT Unbiased estimates of θ = 4Nµ in a random mating population can be based on either the number of alleles or the average number of nucleotide differences in a sample. However, if there is population structure and the sample is drawn from a single subpopulation, these two estimates of θ behave differently. The expected number of alleles in a sample is an increasing function of the migration rates, whereas the expected average number of nucleotide differences is shown to be independent of the migration rates and equal to 4N  Tµ for a general model of population structure which includes both the island model and the circular stepping-stone model. This contrast in the behavior of these two estimates of θ is used as the basis of a test for population subdivision. Using a Monte-Carlo simulation developed so that independent samples from a single subpopulation could be obtained quickly, this test is shown to be a useful method to determine if there is population subdivision.

The Kota of the Nilgiri hills: a demographic study

1976 ◽  
Vol 8 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Aloke Kumar Ghosh
Keyword(s):  
Total Population ◽  
Random Mating ◽  
High Rate ◽  
Moderate Intensity ◽  
Biological Study ◽  
Isolated Population ◽  
Demographic Structure ◽  
Effective Population ◽  
Mating Population ◽  
The Village

A population–biological study of the Kota of the Nilgiri Hills was undertaken between May 1966 and January 1968. This paper discusses the demographic structure of the tribe and its genetic implications.The Kota is a small tribe of 1203 individuals distributed in only seven villages; it is an isolated population with a low rate of fertility and a high rate of infant mortality. The Kota is not a random mating population. The rate of consanguineous marriages is high and the coefficient of inbreeding is almost equal to the highest recorded value. Besides cousin marriages, marriage within the village is very much preferred. The admixture rate (0·29%) among the Kota is very low. The effective population size is only 28·87% of the total population. The coefficient of breeding isolation is 1·01, which indicates that genetic drift may produce important differentiation in this population. The data show that selection is acting with moderate intensity in this population.

scholarly journals R-ISSR - Tool for Generation of a New Type of Products, Applied for the Identification of Putative Molecular Marker Linked to QTL Determined Tolerance to Nutrient Deprivation Stress in Rye (Secale cereale L.)

2012 ◽  
Vol 40 (2) ◽  
pp. 238 ◽  
Author(s):  
Milosz SMOLIK
Keyword(s):  
Genetic Similarity ◽  
Plant Material ◽  
Inbred Lines ◽  
Mantel Test ◽  
Nutrient Deprivation ◽  
Secale Cereale L ◽  
New Type ◽  
Similar Range ◽  
Rapd And Issr ◽  
Issr Primers

This study presents results confirming the possibility of the application of various combinations of RAPD and ISSR primers in one multiplex PCR for the rye genome and generating a new type of R-ISSR products. The plant material consisted of two inbred lines (Ot0-6 and Ot1-3), F1 and two bulks (tolerant and susceptible), selected from a population of RILs (F9) with different responses to stress caused by nutrient deprivation at the seedling stage. In one PCR reaction, the DNA of five genotypes was amplified separately, with RAPD, ISSR, and RAPD+ISSR primers. In total, 28 R-ISSR combinations were tested by combining 20 and 8 appropriately selected RAPD and ISSR primers. 567 loci were amplified, including 230 RAPD, 136 ISSR and 207 amplified R-ISSR loci, of which 114 were new. It was shown that only one ISSR product was identified amongst sequenced R-ISSR products with identical electrophoretic mobility as co-migrating RAPDs and ISSRs. The remaining ones had heteroamplicons (R-ISSR) sequences. A similar range of variability was observed both in R-ISSR profiles and in RAPD, as well as in ISSR. The correlation coefficient between the matrices of genetic similarity for five rye genotypes calculated by means of the Mantel test was highly significant rAB.C = 0.964.

scholarly journals Detecting Linkage between a Trait and a Marker in a Random Mating Population without Pedigree Record

PLoS ONE ◽  
2009 ◽  
Vol 4 (3) ◽  
pp. e4956
Author(s):  
Shuhei Mano ◽  
Takaho A. Endo ◽  
Akira Oka ◽  
Akira Ozawa ◽  
Takashi Gojobori ◽  
...  
Keyword(s):  
Random Mating ◽  
Random Mating Population ◽  
Mating Population

scholarly journals Does segregating variation in sexual or microhabitat preferences lead to non-random mating within a population of Drosophila melanogaster ?

2009 ◽  
Vol 6 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Brad R. Foley ◽  
Anne Genissel ◽  
Harmon L. Kristy ◽  
Sergey V. Nuzhdin
Keyword(s):  
Recombinant Inbred Lines ◽  
Random Mating ◽  
Population Level ◽  
Inbred Lines ◽  
Male Mating ◽  
Complex Environment ◽  
Level Variation ◽  
Group Preference ◽  
Female Genotype ◽  
Microhabitat Preferences

Variation in female choice for mates has implications for the maintenance of genetic variation and the evolution of male traits. Yet, estimates of population-level variation in male mating success owing to female genotype are rare. Here, we used a panel of recombinant inbred lines to estimate the strength of selection at many genetic loci in a single generation and attempt to assess differences between females with respect to the males they mated with. We performed selection assays in a complex environment to allow differences in habitat or social group preference to be expressed. We detected directional selection at loci across the genome, but are unable to provide support for differential male success because of variation in female genotype.

scholarly journals IDENTITY COEFFICIENTS IN FINITE POPULATIONS. I. EVOLUTION OF IDENTITY COEFFICIENTS IN A RANDOM MATING DIPLOID DIOECIOUS POPULATION

Genetics ◽  
1977 ◽  
Vol 86 (3) ◽  
pp. 697-713
Author(s):  
C Chevalet ◽  
M Gillois ◽  
R F Nassar
Keyword(s):  
Genetic Variability ◽  
Population Size ◽  
Effective Population Size ◽  
Random Mating ◽  
Matrix Multiplication ◽  
Inbred Lines ◽  
Inbreeding Coefficient ◽  
Effective Population ◽  
The Mean ◽  
Over Time

ABSTRACT Properties of identity relation between genes are discussed, and a derivation of recurrent equations of identity coefficients in a random mating, diploid dioecious population is presented. Computations are run by repeated matrix multiplication. Results show that for effective population size (Ne) larger than 16 and no mutation, a given identity coefficient at any time t can be expressed approximately as a function of (1—f), (1—f)3 and (1—f)6, where f is the mean inbreeding coefficient at time t. Tables are presented, for small Ne values and extreme sex ratios, showing the pattern of change in the identity coefficients over time. The pattern of evolution of identity coefficients is also presented and discussed with respect to N eu, where u is the mutation rate. Applications of these results to the evolution of genetic variability within and between inbred lines are discussed.

THE GENETICS OF FERTILITY RESTORATION IN CYTOPLASMIC MALE-STERILE RYE

1979 ◽  
Vol 21 (3) ◽  
pp. 417-422 ◽  
Author(s):  
G. J. Scoles ◽  
L. E. Evans
Keyword(s):  
Secale Cereale ◽  
Fertility Restoration ◽  
Inbred Lines ◽  
Male Sterile ◽  
Male Sterile Line ◽  
Cytoplasmic Male Sterile ◽  
Restorer Genes ◽  
Secale Cereale L ◽  
Partial Fertility

Three inbred lines of rye (Secale cereale L.) known to be capable of restoring fertility to a cytoplasmic male-sterile line were crossed with the sterile line. The proportions of male fertile, partially male fertile and male sterile plants in F2 and backcross progenies indicated that three dominant restorer genes were present in each line. These were designated Rf1, Rf2 and Rf3, their relative expressivity was Rf1>Rf2>Rf3. Expressivity was dependent upon environment. Partial fertility occurred when certain genotypes carried two of the three alleles as dominant, but was dependent upon genotype and environment.

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