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Population Genetics and Evolution (Evolution and the Origin of Life…
Population Genetics and Evolution
Population Genetics
Natural Selection
cannot operate if genetically identical
Natural Selection (crosslink)
Multiple Selection Pressures
cold
need for pollinators
drought
insect attack
Factors that cause Gene Pools to Change
Artificial Selection- process in which humans purposefully change the allele frequency of a gene pool
Natural Selection- survival of the fittest
Accidents- are events in which organisms cannot adapt
Factors that Are Not Part of Natural Selection
with intention
planning
on purpose
voluntary decision making
Mutation- all genomes are subject to mutagenic factors
gene pool
crossing over increases genetic diversity
the abundance of different alleles within a population and the manner in which the abundance of a particular allele
Rates of Evolution
Most evolution of a plant is very slow
difficult to identify unless it effects the phenotype
Speciation
natural selection caused a new species to evolve
Phyletic Speciation
pollen transfer
seed dispersal
gene flow
vegetative propagation
one species gradually changes and becomes a new species
Divergent Speciation
Abiological Reproductive Barriers
geographic speciation
nonliving feature that prevents two populations from exchanges genes
Biological Reproductive Barriers
sympatric speciation
biological phenomenon preventing successful gene flow
postsygotic internal isolation barrier
prezygotic isolation mechanism
hybrid sterility
hybrid inviablility
reproductively isolated
some populations of a species evolve into a new second species while other stay as the original or change to a third species
Adaptive Radiation
species rapidly diverges into many new species
founder individuals
founder
Convergent Evolution
two species evolve that the strongly resemble each other
when two organisms cannot cross and produce a fertile offspring
Evolution and the Origin of Life
Conditions on Earth Before the Origin of Life
Chemicals Present in the Atmosphere
Second atmosphere- hydrogen sulfide, ammonia, methane and water
reducing atmosphere due to lack of molecular Oxygen
first atmosphere- mostly hydrogen
Energy Source
intense UV and gamma radiation from sun
The UV rays and gamma rays (crosslink)
Heat from kinetic energy and radioactive decay
Electricity from rainstorms
Time Available for the Origin of Life
because there wasn't any oxygen
Had no limits
Chemicals Produced Chemosynthetically
S. Miller constructed a experiment that produced compounds that were not included in the beginning of the experiment
chemosynthesis
the earth's surface was different and chemicals could react spontaneously
Formation of Polymers
by the seaside
in small ponds
accumulation of monomers
water that is not yet frozen
in the clay
Aggregation and Organization
proteins had an hydrophylic interior
proteins had an hydrophobic exterior
fatty acids occupy the outermost layer
first aggregation would form at random
Early Metabolism
heterotrophs consume certain nutrients
scarcity occurs
complete heterotrophs
metabolic pathway two step
Oxygen
water is released as a waste product
present day atmosphere is a oxidizing atmosphere
evolution of chlorophyll a
allows the world to rust
created conditions for evolution of aerobic respiration
formation of ozone layer
