Chapter 17: Population Genetics and Evolution
Population Genetics
Speciation
Phylectic #
Rates of Evolution
gene pool
Factors that Cause the Gene Pool to Change
Accidents
Artificial Selection #
Natural Selection #
Others
Situations in which Natural Selection does not Operate #
Multiple Selection Pressures
gene flow
Vegetation Propagation
Seed Dispersal
Divergent
Reproductive Isolation
Biological Reproductive Barriers
Adaptive Radiation
Convergent Evolution
Conditions on Earth before the Origin of Life
Chems. Present in Atmosphere
Energy Sources
Chems. Produced Chemosynthetically
Formation of Polymers
Aggregation and Organization
Early Metabolism
Oxygen
Presence of Life
abundance of different alleles and it’s increase or decrease
Mutation
total alleles in sex cells of population
occur continuously
depend mainly on population size
events where an organism cannot adapt
natural phenomena
process in which humans alter gene pool
selective breeding
desirable qualities
correlated with mutagens
“survival of the fittest”
changes to gene pool
most important *evolution
population sufficient to maturity
progeny differ in alleles
offers genetic diversity
differential survival
plants do not have intention or decision making skills
no operation in identical populations
must need competitors and reasons to adapt
allele benefits can depend on habitat
become more or less advantageous
very slow
showcased by phenotypes
difficult to identify loss
natural selection causes new species to evolve
gradually becomes so changed that it =new species
Pollen Transfer
original species, new species, side species,
one full haploid genome
movement of alleles physically thru space
dispersed rapidly by birds, winds, insects
fall close to parent
can be carried by wind, water, animals
small mobile pieces that reproduce vegetatively
Abiological Reproductive Barriers
any physical, nonliving feature that prevents two pops from exchanging genes
speciation
allopatric/geographic
any biological phenomena that prevents gene flow
mountains, rivers, desserts , oceans etc.
flower color, shape, fragrance etc.
speciation
sympatric
isolated but grow together
species divided and can’t interbreed
prezygotic isolation mechanisms
evolutionary changes due to differences in large populations
act before a zygote can be formed
Postzygotic internal isolation barriers
two sub populations considered separate
hybrid sterility
sterile plant
failure of synapsis
hybrid inviability
zygote dies early in development
special case
diverge rapidly into many new species over short time
due to new habitat w/ less stress
offspring resemble “founder”
new alleles build up fast
homogenous
genetic drift
change in gene pool erratically
heterogenous
can happen on mainland in sudden environmental changes
distinct species evolve to resemble each other
occupy similar habitat
chemosynthesis
chemical and phys processes that allowed life
mostly hydrogen
second atmosphere
reducing atmosphere
complex chem is second atmosphere
sun
heat
radioactive decay
radiation
volcanoes, electrical storms, intense lightning
intense energy
planetary cooling
accumulation of lakes oceans streams etc.
long series of slow transitions
blurred line between living and nonliving
Oxidizing atmosphere
plausible model of chemosynthetic hypothesis
monomers had to polymerize in the early ocean
into masses with organization and metabolism
fatty acids
heterotrophs
had some simple metabolism
no genetic storing
no natural selection
genetics introduced
efficiency=mutations
aggregates =heterotrophs
evolution of chlorophyll a
rust
conditions for aerobic resp.
sedimentary rocks showcase age
from early second atmosphere
critically important for all life
especially us humans