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Population Genetics and Evolution (Evolution and the origin of life…
Population Genetics and Evolution
Population genetics
Factors that cause the gene pool to change
Mutation
Existing alleles decrease
New alleles increase
Accidents
Events to which an organism cannot adapt
Artificial selection
Humans purposely change the allele frequency in a gene pool
Natural selection
Those most adapted to the environment survive
Most significant factor causing gene pool changes
Two conditions
Population must produce more offspring than the habitat can hold
The progeny must differ from each other in their types of alleles
Factors that are not part of natural selection
Purpose
Intention
Planning
Voluntary decision making
Situations in which natural selection does not operate
If all in a population are genetically identical
Habitat can support growth and reproduction of all individuals
Multiple selection pressures
Deals with the abundance of alleles in a population
Manner in which the abundance of alleles changes
Evolution and the origin of life
Conditions on earth before the origin of life
Chemicals present in the atmosphere
Mostly hydrogen
Energy sources
UV and gamma radiation
Heat
Electricity
Volcanoes
Time available for the origin of life
No limits
Lack of free molecular O2
Chemicals produced chemosynthetically
Experiments test the effect of atmospheric conditions
Formation of polymers
Requires high concentration of monomers
Aggregation and organization
Aggregation of chemical components into masses that had some organization and metabolism
Early metabolism
Glycolysis
Absorb some ATP and generated more by fermentation
Oxygen
Photosynthesis added oxygen to the atmosphere
The presence of life
Slow, gradual transitions from completely inorganic compounds to living bacteria
Chemosynthesis
Uses only known chemical and physical processes
Rejects divine intervention
Speciation
Phyletic speciation
A species gradually becomes so changed that it must be considered a new species
Pollen transfer
Seed dispersal
Vegetative propagation
Divergent speciation
Some populations of a species evolve into a new, second species
Abiological reproductive barrier
Any physical, nonliving feature that prevents two populations from exchanging genes
Biological reproductive barrier
Any biological phenomenon that prevents successful gene flow
Flower color, shape, or fragrance
Adaptive radiation
Special case of divergent evolution
Species rapidly diverges into many new species over an extremely short time
Convergent evolution
Two species evolve to greatly resemble each other
Evolution causes a new species to evolve
Rates of evolution
Most evolution is very slow
Loss of a structure or metabolism results in quick evolution
