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Allele Frequencies, Types of Selection & Hardy-Weinberg. Evolution of Populations: Chapter 16. Evolution of Populations Notes. Tuesday, 2/21/12 Take out Notebook Turn in: Natural Selection of Antibiotic Resistance Lab and Adaptation Project. Evolution of Populations Notes.
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Evolution of Populations:
Take out Notebook
Turn in: Natural Selection of Antibiotic Resistance Lab and Adaptation Project
Evolution is any change in the relative frequency of alleles in the gene pool of a population. (also called microevolution)
Remember: Alleles are different forms of genes.
Microevolution: The frequency of an allele in a gene pool of a population depends on many factors and can change over time.
A gene pool is the combined genetic information of all members of a particular population.
Expressed in percent.
Individuals with favorable genetic variations will survive and reproduce. Individuals that lack adaptations will most likely die before they ever reproduce. Thus, alleles that are favorable will become more common and those that are not will decrease.
Changes in the DNA and therefore in the genes!
Genetic Drift is usually caused by natural disasters like a fire or flood.
the founder effect-when a migration of a small subgroup of a population causes a change in allele frequencies. (also called bottleneck affect)
Based on this info and what you know about evolution, do you think genetic drift will help a population survive or will it cause the population to go extinct? Why?
Gene Flow: the movement of alleles into or out of a population.Immigrants add new alleles.Emigrants take alleles awayGene Flow Animation:http://nortonbooks.com/college/biology/animations/ch17a01.htm
Sexual Selection can cause sexual dimorphism: when males and females of the same species look noticeably different from each other
This means that females do not just want to mate with a male with a pretty tail for the look of him- females want to mate with males with pretty tails because they could have only produced this tail if he was able to find nutritious food. The female wants a male who is healthy enough to find food and can provide her offspring with nutritious food too.
Males have traits like showy plumage in spite of their potential costs such as increased visibility to predators.
Don’t just copy the sentences in bold.
Try to understand what the question is asking and answer it!
If evolution is change in allele frequency in a population, what if some alleles are lethal? Will the population survive? Will the alleles stay in the population?
Read popcorn style!
Warm-Up: Write down Table of Contents!
Why are alleles that are lethal in a homozygous individual maintained in the gene pool?
(Use Sickle Cell and Malaria as an example.)
… there are two phenotypes, whereas in polygenic traits, there are multiple phenotypes.
Natural Selection acts differently on each of these.
Single Gene Trait!
…changes in allele frequencies and therefore, evolution!
This was shown in the Peppered Moth Simulation.
Animation of Directional Selection:
Animation of Stabilizing Selection:
Animation of Disruptive Selection:
p + q = 1
p2 + 2pq + q2 = 1