Major HBR cases concerns on a whole industry, a whole organization or some part of organization; profitable or non-profitable organizations. Case study method guide is provided to students which determine the aspects of problem needed to be considered while analyzing a case study.
We investigated whether there was natural genetic variation for recombination frequencies and whether any such variation was environment related and possibly adaptive.
First- and second-generation descendants from selfing the original strains from the harsher, more variable, south-facing slope had higher frequencies of crossing over in locus-centromere intervals and of gene conversion than those from the lusher north-facing slopes.
There were some significant differences between strains within slopes, but these were less marked than between slopes. Such inherited variation could provide a basis for natural selection for optimum recombination frequencies in each environment.
There were no significant differences in meiotic hybrid DNA correction frequencies between strains from the different slopes. The conversion analysis was made using only conversions to wild type, because estimations of conversion to mutant were affected by a high frequency of spontaneous mutation.
There was no polarized segregation of chromosomes at meiosis I or of chromatids at meiosis II. TO understand biodiversity, adaptation, and evolution, one must explore the causes of variation and the controls of processes causing genetic variation.
Most natural inherited variation arises through mutation and recombination, and Zhuchenko and Korol concluded that in higher Eukaryotes, recombination plays a greater role in the short-term release of variability than does mutation.
We used 11 ascospore color mutations that occurred spontaneously in three strains isolated from the wild, with six mutations from two southfacing slope SFS strains and five from one north-facing slope NFS strain.
Our aims were to see whether there were significant differences in recombination properties between the strains overall, between strains from the two different slopes SFS and NFSor between strains from the same slope; to determine whether two different aspects of recombination—crossing over in the gene-centromere intervals and gene conversion—showed similar or different changes between strains; and to see whether recombination differences were consistent in amount and direction for different intervals crossing over or for different mutation sites gene conversion.
We were particularly interested in whether any differences were environment related and possibly adaptive. Our mutation studies Lambet al. Three different aspects of meiotic gene conversion were studied: The mutations were also mapped from crosses between them.
For a review of recombination in Ascomycete fungi, including crossing over, gene conversion, and interference, see Lamb This was of interest in its own right and because apparent polarized segregation is an indicator of the differential maturation and dehiscence of different ordered octad classes, which can bias recombination results Lamb The increased solar radiation acts through soil, air moisture, and temperature on living organisms, but both slopes are of geologically identical eroded Upper Cenomanian limestone.
Wild strains of S. The Evolution Canyon project aims to study, at a microscale, biodiversity i. It attempts to assess the relative importance of the driving evolutionary forces caused by interslope differential solar radiation, which gives physically and biotically different organisms on the opposite slopes reviewed by Nevo The ascospore color mutations, where genes for wild-type black can mutate to give white or other colors Olive ; Kitani and Olivewere isolated as spontaneous mutants during our studies of mutation Lambet al.
The wild isolates were obtained vegetatively, not from ascospores, and were subcultured as little as possible, using large inocula to minimize genetic drift.
Selfed generation 1 strains were isolated by germinating black ascospores from the original wild-type strains, and selfed generation 2 strains were obtained from selfed generation 1 black ascospores. Because there can be some effects of premeiotic conditions such as temperature on recombination at meiosis in Sordaria Lamb band because we wanted to study inherited recombination frequencies, only strains of selfed generations 1 and 2 were used in the recombination experiments.
They had existed only under our standard lab conditions. For comprehensive reviews of stress and evolution, see Hoffmann and Parsons and Parsons For variability of recombination and evolution, and for computer simulations of the effects of changing environments and other factors such as linkage on selection for recombination modifiers, see Korol et al.
See Bell for theories of sex and recombination and their evolutionary and ecological advantages and disadvantages. While there has been a lot of modeling of theoretical situations, and some studies of specific recombination mutations, there have been few experimental studies on the genetic control of recombination in wild organisms in relation to their environments.
The theoretical studies have usually been of sexually reproducing diploids, but the haploidy of Sordaria changes aspects of selection because deleterious recessive alleles are not protected from selection in heterozygotes.
Strains were isolated between August and February ; see Lamb et al.Students will grow wild type, and mutant Sordaria strains on mating agar and examine the ascospores under a microscope (available separately). They will then calculate the distance in map units between the gene for ascospore color and the chromosome centromere.
Genetics Lab final exam (ex 1, 2,3,4,6) STUDY. PLAY. PUPATE.- adult form develops. imerge as imagos (slender, elongated, and light in color, wings crumpled and unexpanded.
Flies reach maturity in a few hours, becoming darker and more rorund, wings expand to full size. What is Sordaria Fimicola. Genetics of Ascospore Color in Sordaria lab Introduction: To achieve genetic experiments with haploid organisms, genetic strains of different genotypes must be crossed from one another.
Following fertilization and meiosis, the meiotic products can be analyzed as . Genetics of Ascospore Color in Sordaria lab. Topics: Allele, The trait followed was the ascospore color. Ascospore color is a single gene trait therefore it is easily observed under a light microspore.
Which allele is dominant is very tough to say, because dominant and recessive does not apply in this case. (Sordaria Genetics). LAB 10 – Meiosis and Tetrad Analysis Lab 10 Page 2 of 10 Sordaria fimicola is an ascomycete fungus that can be used to demonstrate the results of crossing over between the centromere of the chromosome and the gene for ascospore color.
To Cross Over . The objective of this lab was to study and test the sordaria fimicola fungus crossover by determining what color it will yield during meiosis.