Population Genetics and Evolution
Population Genetics
the abundance of different alleles within a population
population concept of species
similar ranges of variation occur in species
type concept of species
concept of species on types
gene pool
total number of alleles in all the sex cells of the population
Factors that cause change to gene pool
Mutation
Accidents
Artificial Selection
humans purposefully change the allele frequency
Factors not Part of Natural Selection
Purpose
intention
planning
voluntary decisions making
Speciation
natural selection that caused a new species to evolve
Phyletic Speciation
one species gradually becomes so changes
Divergent speciation
evolve into new species while other populations either unchanged or new third species
gene flow
movement of alleles physically through space
pollen transfer, seed dispersal, and vegetative propagation
reproductively isolated
abiological reproductive barrier
nonliving feature that prevents two populations from exchanging genes
allopatric
geographic speciation
divided into two or more populations cannot interbreed
biological reproductive barrier
biological phenomenon that prevents successful gene flow
sympatric speciation
two groups become reproductively isolated even though they grow together
prezygotic isolation mechanism
act before a zygote can be formed
postzygotic internal isolation barriers
genomes are too different
hybird sterility
two populations occasionally interbreed or are artificially cross-pollinated
hybird inviability
zygote or embryo dies in early development
adaptive radiation #
species rapidly diverge into many new species in short time
founder individuals
all offspring
initial gene pool is small
genetic drift
gene pool can change quick and erratically
Convergent Evolution
evolve to the point they resemble each other strongly
Evolution and Origin
chemosynthesis
seriously considered hypothesis about the origin of life on Earth
Conditions on Earth before life
second atmosphere
produced by release of gases from the rock matrix composing Earth
reducing atmosphere
due to the lack of molecular oxygen
oxidizing atmosphere
derived from the 2nd atmosphere by addition of oxygen by photosynthesis
