[4] Introduction to Natural Selection

[4] Introduction to Natural Selection - Introduction to...

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Introduction to Natural Selection
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Objectives What is natural selection? Examples of natural selection How natural selection operates Required Reading: Text Sections: 3.1, 3.2, 3.4, and 3.5. Sections 3.6 and 3.7 are strongly recommended
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What is Natural Selection? Darwin’s greatest contribution to evolutionary biology Proposed that natural selection was the mechanism through which evolution takes place Definition Differences in the contribution of various Phenotypes to the next generation A difference between the survival and reproduction of individuals with certain phenotypes compared to individuals with other phenotypes
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Natural Selection Living things produce more offspring than can be supported There is a constant struggle for existence . Individuals in a population vary in their phenotypes . Some of this variation is heritable (genotypes ) . Those individuals best adapted to current conditions are most likely to survive and reproduce themselves If these adaptations are heritable, they will be passed on to their offspring. Natural selection acts on phenotypes, but only if there is a change in allele frequencies (eg Genotypes) in a population has evolution occurred. Population genetics is the study of allele and genotype frequencies and their changes in entire populations.
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Evolutionary Fitness (or Darwinian Fitness) The term ‘fitness’ refers to an individuals contribution to the next generation. The more offspring an individual contributes to the next generation, the greater the individuals evolutionary fitness
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Fitness is a measure of reproductive success, which is affected by three different elements of selection: Viability or Mortality Selection: an individuals ability to survive and reach reproductive age Sexual Selection:
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[4] Introduction to Natural Selection - Introduction to...

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