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BIOl 1003 Exam 1 class 4 and 5
Terms in this set (20)
What is an allele?
variation in genes
How are allele frequencies in a population calculated? How can evolution be detected through
monitoring of allele frequencies?
To detect evolution we determine the proportion of each gene form within a population.
Darwin once noted that "The sight of a feather in a peacock's tail, whenever I gaze at it, makes me
sick!" What was the basis of this reaction to peacocks? What aspect of the operation of natural selection was Darwin initially failing to consider that led to this reaction?
He reacted like this because they are showing off and how could evolution not completely kill of male peacocks. He was failing to realize that female peacocks may actually base their male selection off of their tails.
Discuss the conclusions reached from each of the figures provided on Slides 10-14. How do these data, collectively, indicate that this population of peafowl is evolving and that it is evolving adaptively?
It shows that the area and number of eye spots impacts the number of mates the male has. Therefore it implies evolution is occurring because the male spot is becoming more relevant.
If peahens choose peacocks as mates based on eyespot number/area, is this an adaptive behavior by the females? Explain.
no it is more of a sexual selection
What is sexual selection? How does this concept relate to the following examples: 1) birds-of- paradise, 2) bedbugs, and 3) peafowl?
natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.
What is relative fitness, how is calculated, and what does it tell us about the strength and direction of natural selection?
Relative fitness is the relative genetic contribution of each genotype to the next generation
It is calculated by dividing the largest possible genotype by the other possible genotypes
The higher the fitness the better fit the trait is
What did we conclude from Cynthia Beall's data (Slide 29) on the human population she studied in Tibet? Explain how we reached this conclusion.
The genotype A1A2 has the most relative fitness
What are the four forces of evolution? Which is the only one that consistently leads to adaptation?
mutation, gene flow, genetic drift, and migration
selection always yields adaptation
How can knowledge of relative fitness values of genotypes allow prediction of changes in allele
frequencies in a population? Which evolutionary force operates as a result of differences in relative
fitness values among genotypes?
If we know the reproductive output of each genotype is available, we can use the contribution of the best genotype as the standard and compare all other genotypes to this standard
Predict (i.e., draw on a set of axes) the general pattern of allele frequency change for each of the
populations below, assuming the starting frequency of the A and a alleles are 0.5 in all cases: AA Aa aa
Population 1: 1.0 0.8 0.2
Population 2: 0.4 1.0 0.4
Population 3: 0.9 1.0 1.0
AA for population 1 and 3 is doing well and Aa is doing well for all three
What is mutation? Explain how mutation, acting alone, can cause evolution to occur in a population. Explain why mutation is generally expected to be a weak evolutionary force.
Mutation is a change in the nucleotide sequence of sequence of DNA such that a different allele is created. If one mutation works better than others than that trait will evolve. Mutations are fairly rare and don't usually yield positive things
Explain how the operation of natural selection is dependent on the action of mutation.
if there is a bad mutation it will kill this organism off and it can not pass on its negative mutation
What is gene flow? Explain how gene flow, acting alone, can cause evolution to occur in a population.
Movement of genetic material from one population to another. By bringing a new group of genes allows for new alleles taking precedence
If two populations are identical in allele frequencies and regularly exchange immigrants, is it likely
these populations will evolve due to this regular exchange of individuals? Explain.
they may evolve some
If two populations differ in allele frequencies and regularly exchange immigrants, is it likely these
populations will evolve due to this regular exchange of individuals? Explain.
Yes because all these new allele frequencies will change
What is genetic drift? What is "drifting" when this force is in operation? How is genetic drift due to
the effects of sampling?: what is being sampled and how does this sampling occur?
Small samples can be unrepresentative of the true range of values within a population. If populations evolve drift effects the smaller populations
What is the relationship between population size and the strength of genetic drift as an evolutionary
force? How is the concept of sampling a central concept in this relationship?
Larger the population the less likely the sample will be impacted
Discuss how genetic drift can cause a population to evolve in a maladaptive direction (opposite to
the direction selection is moving the population).
frequencies drift in random directions but drifts effects are likely that allele frequencies will change
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