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Chapter 17: Population Genetics and Evolution (Concepts (new species, slow…
Chapter 17: Population Genetics and Evolution
Concepts
new species
slow process
goes unnoticed
Alfred Russel Wallace
Charles Darwin
natural selection
Population Genetics
Situations in which Natural Selection Does Not Operate
identical genetically
survival is universal
Multiple Selection Pressures
insect attacks
drought
cold
need for pollinators
need for a mechanism to disperse their seed
cold hardiness allele
Factors that Cause the Gene Pool to Change
Mutation
Accidents
Artificial Selection
Natural Selection
Factors that are not part of natural selection
purpose
intention
planning
voluntary decision making
gene pool
Rates of Evolution
slow if plants are well adapted
fast if beneficial mutation arises
Speciation
Divergent Speciation
evolve into new second species
reproductively isolated
abiological reproductive barriers
allopatric/ geographic speciation
mountain ranges
rivers
deserts
oceans
Biological reproductive barriers
sympatric speciation
prezygotic isolation mechanisms
postzygotic internal isolation barriers
hybrid sterility
hybrid inviability
adaptive radiation
founder individual(s)
genetic drift
Convergent Evolution
phenotypes converge
natural selection favors phenotypes
Phyletic Speciation
big change
considered a new species
gene flow
pollen transfer
wind-distributed
animal-mediated
seed dispersal
wind
flood
stream
vegetative propagation
Evolution and the Origin of Life
Conditions on Earth Before the Origin of Life
Chemicals present in the Atmosphere
hydrogen
second atmosphere/reducing atmosphere
hydrogen sulfide
ammonia
methane
water
molecular oxygen was absent
Energy sources
heat
radiation
electricity
volcanoes
time available for the origin of life
"primordial soup"
water
salts
numerous organic compounds
no decomposition of molecules
Chemicals Produced Chemosynthetically
amino acids
sugars
lipids
nitrogen bases
Formation of Polymers
sea side pools at high tide
intense sunlight
high temperatures
absorption by clay particles
Aggregation and Organization
controlled by relative solubility
simple "metabolism"
not postulated
Early Metabolism
two step metabolism
produce enzymes
synthesizing scarce molecules
Oxygen
allows rust
aerobic respiration
bacteriochlorophyll
hydrogen sulfide
sulfur
photosynthesis
chlorophyll a
water
oxygen
oxidizing atmosphere
The Presence of Life
