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CH17: population genetics and evolution (evolution and the origin of life,…
CH17: population genetics and evolution
population genetics
factors that cause the gene pool to change
mutations
existing alleles decrease in frequency
new alleles increase in frequency
occurs constantly
artificial selection
humans change frequency of gene pools
carried out in conjunction w/ artificial mutation
examples
selective breeding of animals
selective breeding of crops
accidents
events in which organisms cant adapt
examples
floods
droughts
volcanic eruption
alleles are destroyed
can be small or large
natural selection
conditions
progeny must differ from each other in their alleles
more offspring being produced than can be supported
most significant factor in gene pool changes
survival of the fittest
can only act on pre-existing alleles
does not cause mutations
multiple selection pressures
certain features become more/less advantageous
selection pressure changes
most things are not cause by a single factor
factors that aren't apart of natural selection
intention
planning
purpose
voluntary decision making
evolution and the origin of life
aggregation and organization
step in chemical evolution
aggregation of chemical components into masses with organization
fatty, hydrophobic accumulated automatically
first aggregates
controlled only by relative solubility
not postulated
formed at random
chemicals produced chemosynthetically
rock samples from moon
interior of meteorites
alcohols, sugars, amino acids, and nitrogenous bases
early metabolism
glycolysis must have evolved early
present in virtually all organisms
aggregates and first cells
generated ATP by fermentation w/ glycolysis
may have absorbed ATP
ETC systems and H+ ion pumping systems evolved
oxidative transport didn't exist yet
formation of polymers
methods of concentration
absorption by clay particles
formation of seaside pools at high tide
requires high concentration of monomers
oxygen
evolution of chlorophyll a and photosynthesis
allowed the earth to rust
lower conc. of O2
oxidizing atmosphere
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addition of O2 from photosynthesis
derived from early second atmosphere
condition on earth before original life
energy sources
heat
volcanos
uv and radiation
electricity
rainstorms
time available for the origin of life
chemosynthetic life
lack of free molecular O2
had basically no time limits
chemicals present in the atmosphere
second atmosphere
produced by released gases from rock matrix
replaced first atmosphere that was lost in space
meteorites
reducing atmosphere
early second atmosphere
lack of molecular O2
powerful reducing agents
presence of life
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physics of living and nonliving systems are identical
important to understand complexity of process
speciation
convergent evolution
result of natural selection favoring 2 different phenotypes
examples
euphorbias
cacti
genotypes cannot converge
two fundamental ways
phyletic speciation
seed dispersal
caused by wind, flooding, and stream flow
long distance dispersal
migratory animals can disperse seeds
vegetative propagation
reproduce vegetatively
various alleles come together by gene flow
small mobile pieces
pollen transfer
carry one haploid genome
all alleles are present in its pollen grains
animal mediated pollination
contributes to gene flow
wind distributed pollen
conifers
grasses
ragweed
divergent speciation
biological reproductive barriers
prevents successful gene flow
sympatric speciation
2 groups become . reproductively isolated
grow together
differences in flower, color, shape, or fragrance
adaptive radiation
special case of divergent evolution
species rapidly diverge into new species
genetic drift
former individuals
initial gene pool is extremely small
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can occur in mainland properties
a-biological reproductive barriers
prevents 2 populations from exchanging genes
physical, nonliving feature
ex. mountain ranges
geographic speciation
when speciation results
allopatric
rates of evolution
disruptive mutations
can occur rapidly
outnumber constructive mutations
can be very advantageous
complexity
can trigger change in metabolism
causes loss of structure
most species diverge into new species very slowly
population are well adapted to their habitat
otherwise they wouldn't exit
related
related
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worlds largest cactus
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the OG rust
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