On page 3, Dr. Shoalem Moalem notes that hemochromatosis is
most common in Western Europeans. Similarly, on page 26, Dr. Moalem notes how
diabetes is also more common among Europeans than other populations. Dr. Moalem
then relates the high frequencies of these diseases to historical and
geographical events. This concept relates to Big Idea 1: The process of
evolution drives the diversity and unity of life. Specifically, Dr. Moalem deals with the idea of genetic drift (the
founder effect and the bottleneck effect).
Dr. Moalem cites the founder effect on page 14 as the reason
for high frequencies of the hemochromatosis in European populations. Define the
founder effect. Relate the founder effect to Viking settlement. How did these
Viking settlements increase the frequency of the hemochromatosis mutation?
Similarly, Dr. Moalem cites the plague and an Ice Age 12,000
years ago that affected the frequency of hemochromatosis and diabetes in
European populations. Define the bottleneck effect. How did these events alter
the evolution of the European populations?
Find an example the bottleneck effect with relation to a
different genetic disorder in humans. What was the event, and how did the
disorder give individuals a selective advantage?
(Dhruv Luthra-- dluthra4@students.d125.org)
The Founder Effect, as defined by the Campbell Textbook, is genetic drift that occurs when a few individuals become isolated from a larger population whose gene pool composition is not reflective of that of the original population. Genetic drift is defined as a process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. When The Vikings came to the European coastline, they brought with them Hemochromatosis. This occurred because the Viking population, of which a large majority had Hemochromatosis, took a small percent of their population, and shipped off to live in Europe. This vikings group brought the Hemochromatosis with them, and introduced this disease to Europeans after a few generations of Vikings-European offspring. This disease, because now that Europeans had it, was now much more known.
ReplyDeleteThe bottleneck effect, as defined by the Campbell Textbook, is genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population. The plague and ice age both affected the European population. The plague presented the bottleneck effect in a manner, where people were killed in mass. Large parts of the population, which had the same genes, had less genes by the end. Small parts of the population with the same gene, had either existed as a small percentage of the population, or was completely wiped out. This meant that the survivors had survived anyway that they could based on evolution. And evolution doesn't choose, it uses whatever disease or gene that helps an organism to survive and reproduce, regardless of later repercussions that can occur from the disease or gene. The same occured in the ice age. Here's instead of disease, Europeans with good immune systems and effective bodily response to extreme cold were selected for. This "selected for" group had, at that time, genes that gave them an advantage in the cold, and that group survived and repopulated larger than before.
Although in event is clear here, Dwarfism is found among the Amish population. However, a possible advantage is that this disease at one time, allowed for small people to hide much more easily than ancestors against prey.
Posted By Anzori Kuchaidze - akuchai3@students.d152.org
The Founder Effect, as defined by the Campbell Textbook, is genetic drift that occurs when a few individuals become isolated from a larger population whose gene pool composition is not reflective of that of the original population. Genetic drift is defined as a process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. When The Vikings came to the European coastline, they brought with them Hemochromatosis. This occurred because the Viking population, of which a large majority had Hemochromatosis, took a small percent of their population, and shipped off to live in Europe. This vikings group brought the Hemochromatosis with them, and introduced this disease to Europeans after a few generations of Vikings-European offspring. This disease, because now that Europeans had it, was now much more known.
DeleteThe bottleneck effect, as defined by the Campbell Textbook, is genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population. The plague and ice age both affected the European population. The plague presented the bottleneck effect in a manner, where people were killed in mass. Large parts of the population, which had the same genes, had less genes by the end. Small parts of the population with the same gene, had either existed as a small percentage of the population, or was completely wiped out. This meant that the survivors had survived anyway that they could based on evolution. And evolution doesn't choose, it uses whatever disease or gene that helps an organism to survive and reproduce, regardless of later repercussions that can occur from the disease or gene. The same occured in the ice age. Here's instead of disease, Europeans with good immune systems and effective bodily response to extreme cold were selected for. This "selected for" group had, at that time, genes that gave them an advantage in the cold, and that group survived and repopulated larger than before.
**The founder effect relates to Big Idea 1 in that a small portion from the original population can bring about different characteristics over time and "drive the diversity" of that population, which over many generations, is considered evolution.
**The following is taken from the the American Journal of Medical Genetics: "The early studies on dwarfism in the
Amish, which was, in fact, not achondroplasia,
led to the recognition of two
recessive conditions: Ellis-van Creveld
syndrome [McKusick et al., 1964a],
which had been previously reported
[Ellis and van Creveld, 1940], and
cartilage-hair hypoplasia [McKusick
et al., 1965], a newly recognized disorder
that was eventually given the formal
name of metaphyseal chondrodysplasia,
McKusick type." One can reach this article @ " http://www.nslc.wustl.edu/courses/Bio3411/woolsey/Archives/2010/Lecture15/Francomano%20et%20al%202003.pdf "
Although in event is clear here, Dwarfism is found among the Amish population. However, a possible advantage is that this disease at one time, allowed for small people to hide much more easily than ancestors against prey.
Posted By Anzori Kuchaidze - akuchai3@students.d152.org