Population Genetics and Evolution
Rates of Evoulation
Speciation
Evolution and the Origin of Life
Population Genetics
Situations in which Natural Selection Does Not Operate
Multiple Selection Pressures
Factors that Cause the Gene Pool to Change
Divergent Speciation
Convergent Evoulation
Phyletic Speciation
Formation of Polymers
Aggregation and Organization
Chemical Produced Chemosynthetically
Early Metabolism
Conditions on Earth Before the Origin of Life
Oxygen
The Presence of Life
Artificial Selection
Natural Selection
Accidents
Factors that are not part of natural selection
Mutations
existing alleles decrease in frequency, and new alleles increase
all genomes are subjected to mutagenic factors
accidents are events to which an organism cannot adapt
can be small events or large
many phenomena qualify as accidents
the process in which humans purposefully change an allele frenuency of a gene pool
used to produced ornamental plants that flower more abundantly
often carried out in conjunction with artificial mutation
individuals that are most adapt to an environment survive
such an important factor in evoulation
refers to the differential survival among organisms that have different phenotypes
natural selection does not include purpose, intention, planning, or voluntary decision making
competition can not occur in a habit that can support the growth and reproduction of all indivduals
cannot operate if all the individuals of a population are identical genetically
a mutation that produces an allele that would result in improved fitness is potentially advantageous selectively
Most population are very well adapted to their habitats
evoluationary changes that result in the loss of a structure or metabolism
allelic compostition of a population could change rapidly
example; the ancestors of cacti lived in a habitat that become progressively drier
vegetative propagation
seed dispersal
pollen transfer
abiological reproductive barries
adaptive radiation
biological reproductive barries
unrelated species occupy the same or similar habitats
pollen grains each carry one full haploid genome
can travel great distance
birds or and insects can usually spread pollen through small areas
can be carry be winds, floods, and stream flow
some plants seeds fall close to the parent
if a species produced small, mobile pieces that reproduce vegetatively, they too contribute to gene flow
alleles are arise at various geographic sites come together by gene flow
nonliving feature that prevents two populations from exchanging genes
the original species is physically divided into two or more populations that cannot interbreed
differences in flower color, shape, or fragrance can be effective barries
occurs when the species enters a new habitat where no competition stress exists
a species rapidly diverges into many new species over a short period of time
evolutionary changes in pollinators can also act as a reproductive barriers for plants
any biological phenomenon that prevents successful gene flow
mountain ranges are frequently reproductive barriers because pollinators do not fly over
prevent pollen from moving from one plant to another, and thus neither pollination nor fertilization occurs
consequence would be that the two species would strongly resemble each other
the chemistry of living creatures is more complex than that of nonliving objects
energy sources
time available for the origin of life
chemicals present in the atmosphere
earth condensed from gases and gases for years and was mostly composed of hydrogen
hydrogen sulfide, ammonia ,methane, and water are present in the second atomsphere
UV and gamma radiation are very powerful energy sources
heat is another energy source which is available to power reactioms
without oxygen, no agent was present to cause any damage
the time available for the chemosynthesis origin of life had no limits because the lack of free molecular oxygen
electricity was abundant on a gigantic scale
coalescence gas
radioactive decay of heavy elements like uranium and radium
chemosynthetically hypotheses were performed by S. Miller
experiment was a container that had boiling water in the bottom and a reducing atmosphere in the top
these experiences tell us what is theoretically possible
polymerization required high concentrations of monomers
monomers present in the early ocean had to polymerize if life were to arise
aggregation of certain types of proteins would have resulted in large regions of hydrophilic sites
first aggregates are not postulated to have been alive or even to have been early stages of life
glycolysis must have evolved early because it is present in virtually all organisms
any mutation that produced a mechanism that could detoxify oxygen had great selective advantage
as aggregates continued to consume certain nutrients
the evolution of chlorophyll and photosynthesis allowed the world to rust
the period of rusting was important for all life because it kept the concentration of free oxygen very low
oxygen is transformed into ozone
the buildup of atmospheric oxygen had other important efects
