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