Concept explainers
The original source of new alleles, upon which selection operates, is mutation, a random event that occurs without regard to selectional value in the organism. Although many model organisms have been used to study mutational events in populations, some investigators have developed abiotic molecular models. Soil et al. (2006. Genetics 175: 267-275) examined one such model to study the relationship between both deleterious and advantageous mutations and
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- In order to perform mutation on an organism, we need: 1. A mutation probability - usually a "small" value 2. A crossover point 3. The number of organisms in the population 4. Both a and barrow_forwardSteven Frank and Laurence Hurst argued that a cytoplasmically inherited mutation in humans that has severe effects in males but no effect in females will not be eliminated from a population by natural selection because only females pass on mtDNA (S. A. Frank and L. D. Hurst. 1996. Nature 383:224). Using this argument, explain why males with Leber hereditary optic neuropathy are more severely affected than females.arrow_forwardRecently, scientists have identified a mutation that is found at high frequency in Finnish populations, located in northern Europe where the winter is very cold. This mutation is believed to be a “cold sensitive” allele that warns people of extreme cold temperatures. Could this allele have undergone a “selective sweep”, if it had suddenly appeared in this northern population of humans? How would such a selective sweep be detected with genome data?arrow_forward
- In response to extreme starvation, some bacterial cells undergo programmed cell death (PCD). In E. coli, PCD is mediated by the toxin-antitoxin pair MazF (the toxin that initiates PCD) and MazE (the antitoxin that keeps MazF in check). PCD lowers the fitness of the bacterial cell, but if the cells in the population are genetically related, then the sacrifice of some cells to keep a subset of the population alive may increase the fitness of that shared genome. There is, however, the risk of mutant "cheaters," cells that do not undergo PCD in response to extreme stress but benefit from the nutrients released from dead cells. Loss of which proteins could result in a cheater cell phenotype? Choose one or more: OA. MazF OB. CIPAP protease OC. glucose 6-phosphate dehydrogenase (G6PD) OD. MazEarrow_forwardTrue or False a.) Evolution creates genetic variation in a population. b.) Fitness refers to an allele's ability to help the organism evade predators. c.) The process of natural selection may increase or decrease the frequency of a particular allele in the population depending on the environment. d.) A potato species acquires a mutation in its catalasegene that allows it to function in very cold environments. However, this catalaseis denatured at room temperature. This is a good example of fitness cost.arrow_forwardThe genetics research lab has sequenced a genomic region with 1000000 basepair of an unknown species. Consider that there is a difference between each pair of these sequences of about 200 basepairs. There is a mutation rate of 1x10^-6 and the generation time is 10 yrs. What is the effective population size of the species? Find the coalescent time.arrow_forward
- In evolutionary terms, an organism's fitness is measured by its 1. a) population rate changes due to environmental pressures 2. b) contribution to the gene pool of the next generation 3. c) rate of genetic variability across mitotically changing exons 4. d) mutation rate due to genetic drift 5. e) all of the abovearrow_forwardIt has been hypothesized that population size affects genome size. What is the proposed relationship? How can it be explained?arrow_forwardBased on the results of this study , which answer choice below is the best interpretation of the data that should be communicated to the publicarrow_forward
- This is a graph of the expected frequency of a deleterious allele, with a constant mutation rate, within a population at different levels of selection against it. 0.000012 0.00001 0.000008 0.000006 0.000004 0.000002 0.2 0.4 0.6 0.8 H = 10 i) What is the overall trend shown? ii) What is the mutation-selection balance? iii) The formula for the equilibrium frequency of a deleterious allele within a population is p^=u/s where u is the mutation rate and s is the selection coefficient. Using the relationships illustrated by this formula, determine the following for a population with two deleterious alleles A and B: a) If A has a high mutation rate and low selection coefficient, and B has a low mutation rate and a medium selection coefficient, which would deleterious allele would be expected to be seen in higher frequency? b) If both A and B have a similar selection coefficient, but B is seen at a higher frequency than A, which allele likely has the highest mutation rate? c) If both A and B…arrow_forwardRefer to the figure above. In their investigation of natural selection on Mc1r alleles (the gene that determines coat color) in Arizona pocket mice, Hoekstra et al. determined the frequency of the D and d alleles in each population. They also determined the frequency of alleles for two neutral mitochondrial DNA genes (genes that do not affect and are not linked to coat color). Why did the researchers include the mitochondrial DNA genes as part of their experimental design? Allele change for the neutral mitochondrial genes serves as an experimental group and gives information on any general background genetic difference among these populations. Allele change for the neutral mitochondrial genes serves as a control and determines coat-color differences among these populations. Allele change for the neutral mitochondrial genes serves as an experimental group and gives information on coat-color differences among these populations. Allele…arrow_forwardName crickets remain unnoticed by the parasitoid flies. To test this idea, Robin dissected the otS males to look for fly larvae. She compared A infection levels for 67 normal males- collected before the flatwing mutation appeared in the population-to 122 flatwing males that she collected after the flatwing mutation appeared. She expected fewer males to be infected by the parasitoid fly after the appearance of the flatwing mutation in the cricket population. Scientific Questions: Why do most male crickets on Kauai have flat wings? Could parasitoid flies have contributed to the loss of song for male crickets? Figure 2: A parasitoid fly, Ormia ochracea, sitting on top of its cricket host, Teleogryllus oceanicus. What is the hypothesis? Find the hypothesis in the text and underline it. A hypothesis is a proposed explanation for an observation, which can then be tested with experimentation or other types of studies. Scientific Data: Use the data below to answer the scientific questions:…arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningBiology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning