deeply answere one : What specific effects do the forces of evolution have on th
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Question
deeply answere one :
What specific effects do the forces of evolution have on the distribution of human variation? How does the Hardy-Weinberg equation inform us?
Compare both the manifestation and effects of Maternal-Fetal Incompatibility between the ABO blood group system and the Rh system.
We discussed the variation, effects of, and heritability patterns of several plasma proteins including Transferrin, Haptoglobin, Lipoproteins, and Ceruloplasmin. Choose three of these and describe the way that they have been used to study population movement, variability, interaction with the environment, and/or ancestral relationships.
Explanation / Answer
.Evolutionary Driving Forces Effecting Genetic Diversity:
It is well known that the main driving forces of evolution in any population are a mutation, natural selection, genetic drift, and gene flow. The ability of these driving forces to perform their role is dependent on the amount of genetic diversity within and among populations. Genetic diversity among populations rises from mutations in genetic material, reshuffling of genes through sexual reproduction, and migration of individuals among populations (gene flow). The effect of the evolutionary driving forces on genetic diversity and evolution depends on the number of genetic variations that already exist in a population. The amount of genetic variation within a given population remains constant in the absence of selection, mutation, migration, and genetic drift.
- New Environment Effect of Genetic Diversity:
The migration of human populations to new and different geographical habitats with different environmental challenges such as new climate, food varieties, and exotic pathogens acted as the selective pressure on human populations that lead to adaptive changes in population genetic makeup to cope with these new challenges in order to achieve the golden goal of survival. This selective pressure “natural selection” leads to the increase of the frequency of favored genetic makeups and the elimination of deleterious genetic makeups that fail to adapt to the new environmental challenges. This in turn may lead to the reduction of genetic diversity. Thus, natural selective events have shaped the present genetic diversity of the existing populations and consequently genetic variants involved in many diseases in both direct and indirect fashion.
Allele frequencies (or percentages, if you prefer) in a population will remain in Hardy-Weinberg Equilibrium (HWE) from generation to generation if the following assumptions are met:
Although these assumptions are rarely true in the natural world, they allow us to calculate an expected allele frequency. Significant differences between the observed and expected frequencies indicate that "something" (i.e. one or more of the above) is going on, and therefore tell us that "microevolution" is occurring.
The Hardy-Weinberg equilibrium principle describes the unchanging frequency of alleles and genotypes in a stable, idealized population. In this population we assume there is random mating and sexual reproduction without normal evolutionary forces such as mutation, natural selection, or genetic drift. In the absence of these evolutionary forces, the population would reach an equilibrium in one generation and maintain that equilibrium over successive generations. The equilibrium for a population with the alleles A and a, for example, would be allele frequencies of .6A and .4a and genotype frequencies of .36AA, .48Aa, and .16aa. By describing specific ideal conditions under which a population would not evolve, the Hardy-Weinberg principle identifies variables that can influence evolution in real-world populations. If a population is not in a state of equilibrium, at least one of the evolutionary forces is at work causing change in the population. Further investigation can determine which variables are influencing the changing population.
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