Mechanisms of Evolution. Genetic Equilibrium. No change in allele frequencies thus evolution is not occuring!!. Microevolution changes in the allele frequencies within a population due to: Genetic Drift (small populations – bottleneck, founder effect) Gene flow (immigration & emigration)
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Genetic Equilibrium • No change in allele frequencies thus evolution is not occuring!!
Microevolution • changes in the allele frequencies within a population • due to: • Genetic Drift (small populations – bottleneck, founder effect) • Gene flow (immigration & emigration) • Non-random mating • Genetic mutations & Variation • Natural Selection
Better Beak Extensions 1. Describe how natural selection played a role in the evolution of the birds.2. Explain what type of selection was displayed – directional, disruptive or stabilizing - at the conclusion of the evolution of the birds in our simulation.3. Explain how genetic drift contributed to the evolution of the bird types.Watch a real example.
Speciation • New species develop due to evolutionary changes that prevent them from interbreeding. • Some mechanisms for speciation include 3 types of isolation that ultimately create Reproductive Isolation(the inability of species to successfully mate with each other)Typically result due to these types of isolation • Behavioral – interaction changes that result from isolation • Geographic – physical separation of the original population • Temporal – changes that result in different active times or mating times • Examples
Patterns of Evolution • Extinctions • The disappearance of species opens doors for others to fill those empty niches.
Patterns of Evolution • Adaptive Radiation • The process of a single species developing into diverse forms that live in different ways • Homologous Structures are a key to this!
Patterns of Evolution • Convergent Evolution • “Unrelated” organisms develop similar solutions to evolutionary pressures • Analogous Structures!
Patterns of Evolution • Co-evolution
Tempo of Evolution • Punctuated Vs. Gradualism