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