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Natural Selection and Evolution
Evolution
• Darwin
• Late 1800s
• Historical View of Earth and its organisms.
• HMS Beagle
• Galapagos Islands
• Mechanism of Evolution is Natural Selection.
• Important Terms
• Species
• Population
• Community
• Gene Pool
• Allele Frequency
• Genetic Equilibrium
• Hardy Weinberg Equilibrium
Evolution: Requirements for
• Evolution—A change in the allele frequency of a population over time.
• Requirements:• 1. Genetic Variability—may
come from mutations and immigration.
• 2. More offspring are produced than can survive (due to limited resources, predation, etc…)
• 3. Some organisms must be better adapted than others.
• 4. There must be differential reproduction rates due to the adaptive characteristics of some members.
• Fitness• Fecundity
Hardy-Weinberg Equilibrium
• Genetic Equilibrium• Hardy-Weinberg Law• Defined evolution by
describing when it would not happen.
• There are 5 requirements that must be met for genetic equilibrium to occur.
• Requirements• 1. No mutations.• 2. No immigration or
emigration.• 3. There must be a very
large population in order to avoid genetic drift.
• 4. There must be no natural selection.
• 5. There must be no sexual selection.
Hardy-Weinberg Equilibrium
• Important Terms• Gene flow• Genetic Drift• The Founder Effect• Ellis-van Creveld
Syndrome• Natural Selection• Sickle Cell example• Sexual Selection• Non random Mating
• Natural Selection Patterns
• 1. Stabilizing—birth weight.
• 2. Directional—peppered moths; DDT resistance
• 3. Disruptive—swallowtail; mimicry example. Dimorphism or polymorphism
More on Evolution
• Inbreeding
• Dangers
• Cheetahs
• Pure bred dogs
• Microevolution
• Macroevolution
• Speciation
• Biological Species Concept
• Reproductive Isolating mechanisms
• Prezygotic• Post Zygotic
Types of Speciation
• Phyletic—gradualism.• Allopatric—separation
by a physical barrier.• Parapatric—Occurs in
adjacent populations due to local environment problems. Plants and barbed wire example
• Sympatric—individuals continue to live with each other. Mostly in plants. Due to polyploidy.
• Hybridization
Patterns of Evolution
• Divergent Evolution—Share a common ancestor, but evolve differently.
• Adaptive Radiation
• Why does it occur?
• Convergent Evolution—become more alike due to environment. Aquatic mammals and fist.
• Parallel Evolution—Related species remain relatively the same due to their environments.
• Coevolution—Plants and pollinators; parasites and hosts.
More on Evolution
• Extinction
• Gradualism
• Punctuated Equilibrium
• Adaptive Radiation
• Why does this pattern occur?
Proof for Evolution
• Homologous features • Analogous features• Vestigial organs• Fossil Record• Radioactive Dating• Comparative Embryology• Comparative Biochemistry and Molecular Biology• Artificial Selection
Origins of the World and Life
• Big Bang Theory• Characteristics of the
Pre-life world• Oparin’s hypothesis• Membrane
Invagination Hypothesis
• Endosymbiotic Hypothesis
• Phylogenetics
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