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Population Genetics and Evolution (Evolution and the Origin of Life…
Population Genetics and Evolution
Population Genetics
Population Genetics
abundance of alleles in a population and how it changes with time.
Gene pool
Total number of alleles in all the sex cells of all individuals of a population.
Factors that cause the gene pool to change
Mutation
Accidents
Artificial Selection
natural Selection
Not Natural Selection
Purpose, Intention, Planning, or Voluntary decision making
Rates of Evolution
Can Occur rapidly
can occur over very long periods of time
most often adaptions to environment for more suitability
not always advantageous sometimes disadvantageous
can be seen in flowers, leaves, fruits, shoots, and trichomes
Speciation
Speciation
natural selection has caused a new species to evolve
phyletic speciation
one species gradually becomes so changed that it must be considered a new species.
Divergent speciation
some populations of a species evolve into a new one
Phyletic speciation
Gene flow
movement of alleles physically through space,
pollen transfer
Seed Dispersal
Vegetative Propagation
Divergent Speciation
reproductively isolated
If alleles in one part of the range do not reach individuals in another part
Abiological Reproductive Barriers
abiological reproductive barrier
physical, nonliving feature that prevents two populations from exchanging genes
allopatric or geographic speciation
original species physically divided into two or more populations that cannot interbreed
Biological Reproductive Barriers
biological reproductive barrier
any biological phenomenon that prevents successful gene flow
sympatric speciation
two groups become reproductively isolated even though they grow together
prezygotic isolation mechanisms
barriers that prevent pollen from moving from one plant to another so that neither pollination nor fertilization
postzygotic internal isolation barriers
two subpopulations must be considered separate species
hybrid sterility
interbreeding or artificial cross pollination to produce a sterile plant
hybrid inviability
zygote or embryo dies early in development
Evolution and the Origin of Life
Chemosynthesis
origin of life using only known hypothesis attempts to model the processes
Conditions on Earth Before the Origin of Life
Chemicals present in the Atmosphere
Second Atmosphere
produced by release of gases from the rock matrix composing Earth and from heavy bombardment by meteorites
reducing atmosphere
lack of molecular oxygen and the presence of powerful reducing agents
Energy Sources
Time Available for the Origin of Life
Chemicals Produced Chemosynthetically
Formation of Polymers
Aggregation of polymers
Early Metabolism
oxygen
oxidizing atmosphere
atmosphere present today derived from the early second atmosphere by the addition of oxygen
The Presence of Life
