0.9 0.8 0.7 0.6 0.5 0.4 0.3 CI C2 0.2 0.1 El 0.0 0 5 10 15 20 25 30 35 40 45 50 Generation a. On the basis of these data, what conclusion might you draw about the evolutionary forces that are affecting the Adh alleles in these populations? b. Cavener and Clegg measured the viability of the different Adh genotypes in the ethanol environment and obtained the following values: Relative viabilit Genotype AdhF/AdhF 0.932 AdhF/Adhs 1.288 Adh /Adhs 0.596 Using these relative viabilities, calculate fitnesses for the three genotypes. If a population has an initial frequency of p = f (Adh") = 0.5, what is the expected frequency of Adh in the next generation in the ethanol environment on the basis of these fitness values? Frequency of AdhS
Evolutionary Genetics
Evolution is known as continuous changes that occur to adjust organisms in their changing environment over many generations. Various theories have been proposed to illustrate the origin of life and organic evolution. The most accepted one is the theory of natural selection by Charles Darwin. According to his postulate, organisms undergo a struggle for existence due to overproduction. To survive in nature, they acquire variations. The inheritable variations are selected by nature, and it leads to the survival of the fittest.
Phenotype Frequency
The majority of populations have a certain degree of variation in their genetic pools. Scientists can predict the genetic variation happening over time by measuring the amount of genetic variation in a population and these predictions assist them in gaining important insights into the processes that allow organisms to adapt to the environment or to develop into new species over generations. This process is referred to as the process of evolution.
Hardy Weinberg Equilibrium
The frequencies of allele and genotype were maintained constant from one generation to another due to the absence of other evolutionary forces. It is otherwise called the Hardy Weinberg principle the field of population genetics.
The larvae of the fruit fly Drosophila melanogaster normally feed
on rotting fruit, which may ferment and produce high concentrations of
alcohol. Douglas Cavener and Michael Clegg studied allelic frequencies
at the locus encoding alcohol dehydrogenase (Adh) in experimental
populations of D. melanogaster (D. R. Cavener and M. T. Clegg. 1981.
Evolution 35:1–10). The experimental populations were established
from wild-caught flies and were raised in cages in the laboratory. Two
control populations (C1 and C2) were raised on a standard cornmeal–
molasses–agar diet. Two ethanol populations (E1 and E2) were raised on
a cornmeal–molasses–agar diet to which was added 10% ethanol. The
four populations were periodically sampled to determine the frequencies
of two alleles at the alcohol dehydrogenase locus, AdhS and AdhF. The
frequencies of these alleles in the four populations are shown in the
accompanying graph.
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