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Population Genetics and Evolution (Evolution and the Origin of Life…
Population Genetics and Evolution
Concepts
Evolution
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Gradual conversion of one species to another
Caused by
Mutations to the gene pool
Natural Selection
Extremely slow process
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Requires thousands of generations
Millions of years
link to www.google.com
Population Genetics
Factors that Cause the Gene Pool to Change
Mutations
Mutations Occur Continuously
Existing alleles decrease in frequency overtime
Accidents
Events that an organism can not adapt to
Organisms die off
Decreasing frequency of certain alleles
Can be small or large
Artificial Selection
Allele frequency in gene pool is purposefully changed
Selective breeding
Used to produce plants the flower longer than others
Natural Selection
Most significant factor in gene pool changes
"Survival of the fittest"
The most adapted individuals live, others die
Differential survival among organisms
Does not cause mutations
Acts only on preexisting alleles
link to www.google.com
Factors that are not part of Natural Selection
Purpose
Intention
Planning
Voluntary Decision Making
Situations in which Natural Selection Does Not Operate
If survival is universal, natural selection does not occur
Multiple Selection Pressures
Gene pool
Total number of alleles in all sex cells of a population
Rates of Evolution
Changes that cause the loss of structure or metabolism
Come about quickly
Changes in gene pool happen overtime
Slow
Happens over many years
Speciation
Phyletic Speciation
Pollen Transfer
Seed Dispersal
Vegetative Propagation
Divergent Speciation
Abiological Reproductive Barriers
A physical, non living feature that prevents two populations from exchanging genes
The original species is divided into separate populations
The populations can't interbreed
If speciation results it is allopathic
Biological Reproductive Barriers
Any biological phenomenon that prevents successful gene flow
Sympatric Speciation
When two groups grow together but are reproductively isolated
Postzygotic Internal Isolation Barriers
Divides species
Prezyogotic Isolation Mechanisms
biological reproductive barriers that keep pollen from spreading
Hybrid Sterility
Two different plants breed to make viable seed
Viable seed produces plant
Plant produces sterile seeds
Hybrid Inviability
One parent alleles may code for proteins that another may not
Seed becomes inviable and dies
Adaptive Radiation
Species rapidly diverges into new species
Convergent Evolution
Where two species evolve together
They end up favoring eachother
link to www.google.com
Natural Selection caused a new species to evolve
Evolution and the Origin of Life
Conditions on Earth Before the Origin of Life
Chemicals Present in the Atmosphere
Most of first atmosphere was lost in space
Due to hydrogen being a light gas
Second atmosphere was formed
Replaced first atmosphere
Produced by release of gases
Reducing atmosphere
Due to lack of molecular oxygen
Energy Sources
UV Rays
Heat
Electricity
Gamma Radiation
Time Available for the Origin of Life
Basically no limits
Chemicals Produced Chemosynthetically
How all the small molecules are formed
Amino Acids
Sugars
Lipids
Nitrogen Bases
Formation of Polymers
Monomers polymerize for arising life
Requires high concentration of polymers
Aggregation and Organizations
The aggregates are not alive
Early Metabolism
Oxygen
Oxidizing Atmosphere
Atmosphere present was derived from early second atmosphere
By addition of oxygen from photosynthesis
The Presence of Life
Chemosynthesis
Tries to model the origin of life
Uses only known chemical and physical properties
