Download EVOLUTION SPECIES LINNEAUS` CLASSIFICATION SYSTEM The

EVOLUTION
SPECIES
LINNEAUS’ CLASSIFICATION SYSTEM
The process of biological change by
which descendants come to differ
from their ancestors
A group of organisms that can
reproduce and have fertile offspring
Organisms are grouped according to:
physical similarities, species can
change
3 IDEAS OF GEOLOGICAL CHANGES
FOSSILS
CATASTROPHISM
1. Catastrophism
2. Gradualism
3. Uniformitarianism
Traces of organisms that existed in the
past
Past natural disasters shaped
landforms, and caused species to
become extinct in the process
GRADUALISM
UNIFORMITARIANISM
Landforms were shaped by very slow
changes over a long period of time,
and not by natural disasters
(accepted theory)
The same processes that shaped
landforms in the past also shape
landforms today
WHAT DID DARWIN OBSERVE?
Variation of the traits among similar
species
VARIATION
ADAPTATION
WHAT CONVINCED DARWIN THAT
EVOLUTION OCCURS?
The differences in the physical traits
among individuals in a group of
organisms among islands
Feature that allows an organism to
better survive in its environment
 The variation of similar species
among islands
 Fossil evidence
 Geologic events
DARWIN’S 4 REASONINGS THAT LED
HIM TO HIS IDEA FOR NATURAL
SELECTION:
1.
2.
3.
4.
Artificial selection
Heritability
Natural selection
Struggle for survival
(Thomas Malthus- food, water, and
shelter are limits to human population
growth)
ARTIFICIAL SELECTION
Humans select and breed individuals
with the traits they desire to produce
more individuals with those traits
HERITABILITY
The ability of a trait to be passes down
from one generation to the next
(Not acquired)
NATURAL SELECTION
POPULATION
FOUR MAIN PRINCIPALS TO THE
THEORY OF NATURAL SELECTION
(Darwin and Wallace)
Process in which individuals that have
inherited beneficial adaptations
produce more offspring than do other
individuals
All the individuals of a species that live
in an area
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Variation (genetic)
Overproduction (competition)
Adaptation
Descent with modification
FITNESS
NATURAL SELECTION ACTS ON
EXISTING VARIATION
SOURCES OF EVIDENCE FOR
EVOLUTION
A measure of the ability to
survive and reproduce
Acts on phenotypes (physical
traits), and not on genetic
material
 Changing environments
 Adaptations as
compromises
(panda bear’s “thumb”)
 Fossils
 Geography
 Embryologythe study of embryos and
their development
 Anatomy
HOMOLOGOUS
STRUCTURES
ANALOGOUS
STRUCTURES
VESTIGIAL STRUCTURES
Features that are similar in
structure, but appear in
different organisms and
may have different
functions (front limbs of
humans, bats, and moles)
Structures that perform a
similar function, but are
not similar in origin
(wings of birds and
butterflies)
Small leftover organs or
structures that had a
function in an early
ancestor
(pelvic bones in whales or
snakes)
PALEONTOLOGY
The study of fossils or
extinct organisms
WHERE THE GENETIC
VARIATION IS STORED?
In a population’s GENE
POOL
Gene Pool
Collection of alleles found
in all of the individuals of a
population
Allele
An alternative form of a
gene; occurs at a specific
place on a chromosome
A measure of how common an allele is
in a population
An allele frequency
Two main sources of
Genetic variation:
Allele frequency = one allele / to the
total # of the alleles
 Mutation
 Recombination
Mutation
Recombination
Hybridization
A random change in DNA
 a new allele  increase
the genetic variation in a
gene pool
New combinations of
alleles form during meiosis
– the type of cell division
that forms gametes (sex
cell; an egg or a sperm
cell).  Many different
genetic combinations
When organisms breed
with organisms of another
closely-related species
Normal distribution
The frequency is highest
for the middle, or mean
phenotype, and lowest at
the two ends, or extreme
phenotypes
The alleles related to the
favorable phenotypes increase
in frequency
Microevolution
Three ways that natural
selection can change the
distribution of a trait
The observable change in
the allele frequencies of a
population over time
 Directional Selection
 Stabilizing Selection
 Disruptive Selection
Directional Selection
Stabilizing Selection
Disruptive Selection
Selection that favors a
phenotype at one end, or
extreme, of a range
(Evolution of antibiotic-resistant
bacteria)
Selection that favors the middle,
or intermediate, phenotype
(Middle-sized gall-fly)
Selection that favors both
extreme phenotypes
(Dull brown birds and bright blue
birds)
Gene flow
Genetic drift
Two processes that cause
genetic drift to occur
The movement of alleles
from one population to
another
A change in allele
frequencies due to change
 Loss of genetic variation
 The bottleneck effect
 The founder effect
The bottleneck effect
The founder effect
When Sexual selection
occurs?
Genetic drift that occurs
after a population has been
greatly reduces in size
(Natural disaster)
Genetic drift that occurs
after a small number of
individuals begin to live in a
new area
Occurs when certain traits
increase mating success,
and gets passed on to the
next generation
Five conditions of HardyWeinberg equilibrium
Hardy-Weinberg equilibrium
describes populations that are
not evolving
The Hardy-Weinberg
equation is used to predict
what?
What is the formula of
genotype frequency in a
population?
 Very large population. No
genetic drift can occur.
 No emigration or immigration.
No gene flow can occur.
 No mutations. No new alleles
can be added to the gene pool.
 Random mating. No sexual
selection can occur.
 No natural selection. All traits
must equally help in survival.
The Hardy-Weinberg equation is used
to predict genotype frequencies in a
population
p² + 2pq + q² = 1
p – Frequency of the dominant allele
q – Frequency of the recessive allele
What are the five factors that can lead
to evolution?
The isolation of populations can lead
to what?
Speciation
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Initial population
Gene Flow
Sexual Selection
Genetic Drift
Mutation
Natural Selection
Speciation
The process of one species becoming
two or more separate species
(Last step is reproductive isolation)
Reproductive isolation
When members of different
populations can no longer mate
successfully
 Behavioral barriers
Name the three types of barriers to
mating
Result in behavioral isolation, isolation
caused by differences in courtship and
mating behaviors.
 Geographic, or physical
Result in geographic isolation, such as
when a river or mountain divides a
population into two or more groups
 Temporal barriers
Result in temporal isolation, when timing
prevents reproduction between populations
 Convergent evolution (to come
together) is when unrelated species
Name the two ways that natural
selection can direct a population’s
traits
evolve similar characteristics
(Wing on birds and insects)
 Divergent evolution (to move
apart) is when closely related
species evolve in different
directions, and become
increasingly different
(kit fox and red fox)
The process in which two or more
species evolve in response to changes
in each other
Co evolution
Extinction
 Beneficial relationships
(The bull-thorn acacia and stinging
ants)
 Competitive relationships
 (shells evolved to become thicker and
spinier  crabs evolved more
powerful claws)
The permanent loss of species from
Earth
(Natural process)
Name the two categories of
extinction?
 Background extinctions – occur
continuously, but at a low rate,
one or few species are affected
 Mass extinctions – destroy many
species, often all across Earth,
occur suddenly in geologic time,
because of dramatic event like
as ice age or a asteroid impact
Punctuated equilibrium
Theory that states that speciation
occurs suddenly and rapidly followed
by long periods of little evolutionary
change
Adaptive radiation
The rapid evolution of many diverse
species from ancestral species. 
Many different species spread out in
different environments