POPULATION GENETICS
INTRODUCTION TO SCIENCE
SPRING 1999

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At the end of this section you need to be able to address the following:
 

1.   What is the value of the Hardy-Weinberg equation?  How is it useful in studying population genetics?
2.    What are the five conditions necessary for a Hardy-Weinberg equilibrium to exist?
3.    What is natural selection?  What are the four premises of the concept of natural selection?
4.     Give a one-sentence definition of evolution.
5.     In what way does chance play a role in evolution?
6.    Assuming that each of the following lines of evidence was true, which would NOT support Darwin's theory of evolution by natural selection?
• Fossil records, which were thought to be quite complete, showed no examples of organisms that were intermediates (or links) between two related species, one older and one younger in the fossil record.
• Studies of anatomy showed the presence of degenerated, non-functional (vestigial) structures in a number of different vertebrates
• Nearly all offspring of animals studied in nature survive to reproduce.
• Studies of natural populations show a large amount of variation in characteristics.
• The genetic code is different for eukaryotes and prokaryotes.
• The earth is very, very old, about 4.5 billion years old.
7. Approximately one child in 10,000 is born with PKU (phenylketonuria).  What is the frequency of this allele in the population?  What is the frequency of the normal allele?  What is the percentage in the population of carriers of this trait?
8. The introduction of DDT to control mosquitoes in the 1940s brought rapid control over the mosquitoes carrying the malarial pathogen.  Today, resistance to DDT has developed in many mosquito populations and is reducing the effectiveness of malarial-control programs.  Explain how it was possible for the mosquitoes to evolve DDT resistance in such a short time.
9. The fossil record shows that the few surviving species of horseshoe crabs have existed unchanged for the past 200 million years.  How do you account for the fact that there has been essentially no evolution of the species over this time span?