Transcript I. Evidence of Evolution A. Fossils - River Dell Regional School District

Evolution
Biology
RiverDell High School
Ms. C. Militano
I. Evidence of Evolution
A. Fossils
1. definition - trace or remains of
organisms that are preserved
2. types
a. mold (rock imprint)
b. cast (mold that is filled)
c. petrified
d. preserved in amber or tar pits
Mold Fossil
Cast Fossil
Fossil in Amber
Petrified Wood
Dinosaur Fossils
Toe of a Dinosaur
Plant Fossils
Flower Fossil
Cone Fossil
I. Evidence of Evolution
A. Fossils
3. location
a. sedimentary rock
b. amber or tar pits
4. distribution
a.Law of Superposition(Steno 1638-1686)
1) relative age
2) absolute age
b. biogeography
Fossils Are Found in Tar Pits
Sedimentary Rock Showing Layers
Law of Superposition – younger fossils are
closer to the surface – older fossils are deeper
I. Evidence of Evolution
B. Comparative Anatomy
1. homologous structures
a. similar structure, evolution,
development
b. wing, arm, flipper)
2. analogous structures
a. similar function
b. wing of a bird and an insect
Homologous vs Analogous Structures
I. Evidence of Evolution
B. Comparative Anatomy
3. vestigial structures
a. useful in past organisms but not
now
b. appendix, tail vertebrae,
ear muscles
Vestigial Structures
Appendix in Humans
Leg Bones in a Whale
I. Evidence of Evolution
C. Embryology Similarities
1. Haeckel(1834-1919) [German]
a. “ontogeny recapitulate phylogeny”
1) embryo undergoes changes
that repeat evolutionary
development
Diagram Showing Similarities in Early
Stages of Embryo Development
I. Evidence of Evolution
D. Biochemistry
1. similarity in amino acids in specific
proteins
2. similarity in RNA and DNA base
sequences
Comparing Amino Acid Differences of
Several Organisms to Humans
II. Theories of Evolution
A. Lamark (1744-1829)
1. Acquired traits – traits that
develop during one generation
can be passed to the next
generation
2. Law of Use and Disuse – if a trait
is not used it will be lost
Lamarck and Law of Use and Disuse
According to
Lamarck the
giraffes pictured
grew longer necks
in order to reach
the leaves in taller
trees
The longer necks
were then passed
to the next
generation
II. Theories of Evolution
B. Charles Darwin(1809-1882)
1. Biography
a. Darwin attended medical school
b. studied to be a clergyman
c. 22 years old - signed on
HMS Beagle
1) collect specimens as a naturalist
2) refined data for 21 years
Charles Darwin
Darwin’s Home
HMS Beagle in Sydney Australia Harbor
Darwin’s Voyage
II. Theories of Evolution
B. Charles Darwin(1809-1882)
2. The Origin of Species (1859)
a. Descent with modification
1) all species descend from a
small number of original types
2) there is variation among
organisms
II. Theories of Evolution
B. Charles Darwin(1809-1882)
b. Modification by Selection
1) environment limits growth of populations
-competition for life’s necessities
-specific traits are selected
2) adaptive advantage
- trait favorable for a given environment
- adaptations make some organisms
more likely to survive than others
II. Theories of Evolution
B. Charles Darwin(1809-1882)
3) fitness - ability of an organism to
make a genetic contribution to the
next generation
4) natural selection allows individuals
with survival adaptations to pass
traits to offspring
II. Theories of Evolution
B. Charles Darwin(1809-1882)
5) speciation - formation of new
species as favorable adaptations
accumulate
6) “survival of the fittest” - those
organisms with favorable traits
reproduce and pass their traits to
future generations
III. Patterns of Evolution
A. Coevolution
1. changes in two or more species
closely associated
2. examples
a. predator and prey
b. parasite and host
c. plants and plant pollinators
III. Patterns of Evolution
B. Convergent Evolution
1. similar phenotypes are selected but
ancestors are very different
a. natural selection of analogous
structures
2. examples
a. wings in insects and birds
b.fins & shape of sharks, fish, porpoise
Examples of Convergent Evolution
III. Patterns of Evolution
C. Divergent Evolution
1. two or more related populations or
species become more dissimilar
a. speciation - new species may form
2. example
geographic isolation
a. brown bear

polar bear
III. Patterns of Evolution
C. Divergent Evolution
3. adaptive radiation
a. many species evolve from same
ancestor
1) ancestor migrates to different
environments (example) Galapagos finches
Adaptive Radiation – Darwin’s Finches
Beak shape Depends Upon Food Source
Adaptive Radiation – Hawaiian Honeycreepers
IV. Variation in Populations
A. Distribution of variations
1. graph is a bell curve
B. Natural Selection and Changes in
Populations
1. Stabilizing Selection – favors average
form
2. Directional Selection – average shifts
to one extreme or the other
3. Disruptive Selection – extreme forms
are favored- number of individuals
with the average form is reduced
Stabilizing Selection
Directional Selection
Disruptive Selection
Comparing Types of Selection
Comparing Three Types of Selection
IV. Variation in Populations
C. Genetic Sources of Variation
1. Mutations
a) a specific gene mutates in
1/10,0000 gametes
b) thousands of genes in each gamete
c) some mutations in every zygote
d) most mutations are recessive
IV. Variation in Populations
C. Genetic Sources of Variation
2. Genetic Recombination
a) random meeting of sperm and egg
b) crossing over
c) independent assortment
3. Genetic Drift
a) occurs in small populations
b) elimination of some genes by chance
c) may decrease variation
IV. Variation in Populations
C. Genetic Sources of Variation
4. Non-random Mating
5. Migration
a) immigration- movement into an
area or population
b) emigration – movement out of an
area or population
IV. Variation in Populations
D. Genetic Equilibrium
1. Hardy-Weinberg Principle
a) allele frequencies are stable across
generations
b) sexual reproduction alone does not
affect genetic equilibrium
2. Conditions Necessary
a) no immigration
b) no mutations
c) no natural selection d)large populations
e) random mating
IV. Variation in Populations
E. Mathematics/Hardy Weinberg
1. gene pool - all the genes in a population
2. allele frequency - % occurrence of a
specific allele in a population
3. phenotype frequency - % occurrence of
an individual in a population with a trait
4. genotype frequency - % occurrence of
individuals in a population with a specific
genotype
IV. Variation in Populations
E. Mathematics/Hardy Weinberg
5. applying mathematics
a) p = frequency of the dominant allele
q = frequency of the recessive allele
b) p + q = 1
c) p2 + 2pq + q2 = 1
IV. Variation in Populations
E. Mathematics/Hardy Weinberg
d) q2 = recessive phenotype/genotype
frequency
p2 +2pq = dominant phenotype
frequency
p2 = pure dominant genotype frequency
2pq= heterozygous genotype frequency
V. Speciation and Rate of Evolution
A. Species - organisms that are
morphologically similar and can
interbreed to produce fertile offspring
1. Speciation - process of forming
species
V. Speciation and Rate of Evolution
A. Species and Speciation
2. Isolating mechanisms that result in
speciation
a) geographic barriers separate populations
1) gene flow stops and natural selection
and genetic drift result in divergence
b) reproductive barriers - prevent breeding
of organisms in the same geographic area
V. Speciation and Rate of Evolution
B. Rate of Evolution
1. evolution may be defined as
a) change in genetic material in a
population
b) change in allele frequency in a
population
c) change in genotype/phenotype ratio
d) speciation
V. Speciation and Rate of Evolution
B. Rate of Evolution
2. Gradualism (Darwin) - new species arise
slowly and continuously through small,
gradual changes
3. Punctuated Equilibrium (Steven Gould and
Niles Eldredge) - there are long periods (up
to millions of years) with little or no change
- then there is a short period of rapid
change
VI. Evolution in Action
Caribbean Anole Lizards
Live on Tree Trunks
Stocky body
Long legs
Live on Slender twigs
Thin body and large toe pads
Short legs and tails
Caribbean Anole Lizards
Live in grass
Slender body
Very long tails
* at least six anole body types - and
distinct species with same body type
on different islands
Caribbean Anole Lizards
Hypothesis
Specialized twig dwellers lived on one
islands and migrated to other islands
Twig-dwellers evolved independently on
each island from a distinct ancestor (DNA
evidence) – example
of convergent evolution
Caribbean Anole Lizards
Divergent Evolution and Radiation
Divergent evolution on each island
Descendants from a single ancestor
diversify into species adapted for a
specific environment – if populations
fill many parts of the environment it is
called adaptive radiation
Caribbean Anole Lizards
trunk
dweller
twig
dweller
grass
dweller
COMMON ANCESTOR
Arrives on each island