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Population genetics and evolution (Evolution and origin of life. :recycle:…
Population genetics and evolution
CONCEPTS :check:
Evolution :<3:
natural selection
mutations
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new alleles or new genes
more or less adapted to environment
affect fitness to the individual
if beneficial reproduce better
if deleterious reproduce slow or die.
gradual conversion
one species to another , even more
slow process
POPULATION GENETICS :warning:
abundance of different alleles
within a population
crossing over.
increases genetic diversity
manner in which the abundance
increase
decreases
remain unchanged
Factors that causes the gene pool to change
:star:
mutation
:forbidden:
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significance
depends on population size.
all genomes
existing alleles decrease in frequency
new alleles increases
Accidents
:red_cross:
many phenomena's
organisms cannot adapt
collision of large meteorite
with earth
large surface is destroyed
large organism are eliminated.
Artificial selection
:green_cross:
selective breeding of animals
human purposefully change allele frequency
look for desirable quantities.
selective breeding of crops
wild population and cultivated plants.
Natural selection
:red_flag:
survival of the fittest
most adapt to the environment survive
different phenotypes
from different survival.
more offsprings
have different characteristics/traits
inherit traits from parents.
Situations in which Natural Selection Does Not Operate
:warning:
if individuals of a population are identical genetically
competition doesn't occur
natural selection doesn't occur
road cut, burned area,
a recently flooded plain covered with rich sediments.
Multiple selection processes
: :!:
causes by many factors
insect attack
drought
cold
pollinators
Mutation
produce allele that result in improved fitness
result in improved cold hardiness.
may be eliminated from gene pool if killed by fungus
if survive in cold hardiness it may improve species.
cold winter infrequent
does not exert strong selection pressure.
if cold winter are common
greatly improves fitness and frequency increases rapidly.
Rates of evolution :explode:
complexity
#
causes loss of strucutre
can trigger change in metabolism
disruptive mutations
can be very advantageous
outnumber constructive mutations
can occur rapidly
Speciation
:checkered_flag:
Caused by natural selection.
Divergent speciation
:no_entry:
reproductively isolated
Abiological Reproductive Barriers
physical , nonliving
prevents two population
cannot interbreed
allorpatric or geographic speciation
biological reproductive barriers
sympatric speciation
prevents successful gene flow
flower, color, shape or fragnance
evolutionary changes.
some evolve into new species, some remain same
not homogenous througout its entire range
Phyletic speciation
: :!!:
species gradually become so changed
must be considered a new species.
millions of years often required.
movement of alleles called
Gene flow
Pollen Transfer
carry one haploid genome.
good travel distances
ragweed, grasses and confiers.
Seed Dispersal
seeds and fruits.
long distance dispersal
wind , floods and stream flow.
Vegetative propagation.
small , mobile species
gene flow, meiosis, crossing over and genetic recombination.
Evolution and origin of life. :recycle:
chemosynthesis.
origin of life
chemical and physical processes.
species have evolved from those of past.
formation of polymers
necessary for life to arise.
requires high concentration of monomers
oxygen
evolution of chlorophyll a and photosynthetic
allowed the world to rust
evolution of aerobic respiration.
oxidizing atmosphere
adding of oxygen from photosynthesis.
derived from second atmosphere.
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Aggregation and organization
next step in evolution of life
organization and metabolism
fatty, hydrophobic accumulated automatically
presence of life
physics of living and non living system are identical
addition of oxgen from photosynthesis.
conditions and the origin of life
chemicals present in the atmosphere
second atmosphere
replaced first atmosphere that was lost in space
produced by released gases from rock matrix
reducing atmosphere
powerful reducing agents
early second atmosphere
lack of molecular oxygen
energy sources
rainstrom,electricity, UV radiation, heat volcanoes
