Download natural selection

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Bio 100 Spring 2016 Lecture 13
Evolution:
Microevolution –
Macroevolution –
Charles Darwin – Father of Evolution
On the HMS Beagle
Darwin worked as the ship’s naturalist (field biologist),
Two points about Natural Selection
Evidence for Evolution
1. Fossil Record –
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Bio 100 Spring 2016 Lecture 13
2. Homologous structures –
3. Molecular similarities –
4. Artificial selection-
He hypothesized that as the descendants of a remote ancestor spread into
various habitats over millions and millions of years, they accumulated diverse
modifications, or adaptations, that fit them to specific ways of life in their
environment.
The essence of natural selection is this unequal reproduction.
Three key points about evolution by natural selection:
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Bio 100 Spring 2016 Lecture 13
Four requirements for Natural Selection:
Evolution occurs within populations:
What is a population?
Population Genetics – the study of genetic changes in populations.
Gene pool:
The four main causes of evolutionary change are
1. natural selection –
2. genetic drift –
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Bio 100 Spring 2016 Lecture 13
2. Genetic Drift can be caused by bottleneck effect or founder effect
Bottleneck effect –
Founder effect
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Bio 100 Spring 2016 Lecture 13
3. gene flow –
Gene Flow
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Bio 100 Spring 2016 Lecture 13
Transfer of individuals or gametes between populations
4. mutations –
Mutations –
Sources of genetic variation in populationsMutations
Sexual reproduction
Independent assortment
Random fertilization
Independent orientation of homologous chromosomes at metaphase
I of meiosis,
Fitness
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Bio 100 Spring 2016 Lecture 13
Hardy- Weinberg Equilibrium
For a population to be in Hardy-Weinberg equilibrium, it must satisfy five main
conditions.