Population Genetics and Evolution
Population Genetics
The manner in which the abundance of an allele increases, decreases, or remains the same with time
Gene pool
Mutation
Accidents
Natural Selection
Artificial selection
Total number of alleles in all sex cells of a population
Mutations occur continually
Cause new alleles to increase
Cause decrease in existing alleles
Significance depends on population size
For example a large meteorite striking Earth's surface
Decrease alleles in a given area
Organisms cannot adapt to accidents
Can have a large or small impact on allele frequency
Process in which humans change the allele frequency of a gene pool
Selective breeding
Carried out with artificial mutation
Produces ornamental plants
Causes more often flowering
Causes longer flowering period
Most fit survive
Most significant in changing gene pool
Progeny must differ in allele type
Population must produce more offspring than can survive or grow
Rates of Evolution
Evolution is how a population adapts over time to their habitat #
Descendants become more diverse
Changes in evolution can cause loss of structure or metabolism
Speciation
Phyletic Speciation
Allopatric Speciation #
Divergent Speciation
Sympatric Speciation #
Convergent Evolution
Hybrid Sterility #
Seed dispersal
Vegetative propagation #
Pollen transfer
Gene flow
New alleles arise and are selected for #
Wind
Animals
Floods
Egg is fertilized and forms seed with new allele
Contribute to gene flow
Two species evolve resembling one another
Reproductively isolated
Biological reproductive barriers
Abiological reproductive barriers
Species divided, geographically, into two or more populations
Biological prevention of gene flow
Non-living factor keep populations from gene exchange
Prezygotic isolation mechanisms
Prevents pollen from moving from one plant to another
Two groups that become reproductively isolated even though they grow together
Two populations interbreed but offspring cannot reproduce
Evolution and the Origin of Life
Second Atmosphere
Energy Sources
Time available for origin of life
Aggregation and organization
Chemosynthesis
Formation of polymers
Electricity
Radiation from the sun
Heat
Rejects divine intervention
Models the origin of life using only chemical and physical processes
Caused by lack of molecular oxygen
Produced by release of gas from rock matrix
Reducing atmosphere
No limit on time available for chemosynthetic origin #