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Chapter 17: Population Genetics & Evolution (Speciation (convergent…
Chapter 17: Population Genetics & Evolution
Population Genetics
deals with the abundance of different alleles within a population
factors that cause genes to change
mutation
existing alleles decrease in frequency
new alleles increase in frequency
accidents
events to which an organism can't adapt
artificial selection
humans purposefully change the allele frequency of a gene pool
natural selection
most significant factor
survival of the fittest
factors that are part of natural selection
purpose
intention
planning
voluntary decision making
Speciation
natural selection as causes a new species to evolve
two ways
phyletic speciation
one species gradually becomes changed to where it becomes a new species completely
gene flow
movement of alleles physically through space
pollen transfer
pollen grains each carry one full haploid genome
seed dispersal
some fall close to the parent
many have long distance dispersal
vegetation propagation
species produces a small, mobile piece that reproduce vegetatively
divergent speciation
some populations of species evolve into a new, second species
abiological reproductive barriers
physical nonliving feature that prevents two populations from exchanging genes
biological reproductive barriers
any biological phenomenon that prevents successful gene flow
adaptive radiation
species rapidly diverges into many new species over a very short time
convergent evolution
when two unrelated spiced occupy the same or similar habitats
natural selection may favor the same phenotypes in each
the two may evolve to a point where they resemble each other a lot
Evolution and the Origin of Life
chemosynthesis
model the origin of life using only known chemical and physical processes
rejecting all traces of divine intervention
conditions on earth before the origin of life
chemicals present in the atmosphere
mostly hydrogen
second atmosphere
hydrogen sulfide
ammonia
methane
water
energy sources
UV and gamma rays from the sun
time available for the origin of life
no limits
