Download theory of evolution - River Dell Regional School District

THEORY OF EVOLUTION

Footprints activity
14.1 How Did Evolutionary
Thought Develop?

Evolution is the change over time in the
characteristics of a population


Population is all the individuals of one
species in a particular area
Modern biology is based on our
understanding that life has evolved, a
principle unrealized by early scientists
14.1 How Did Evolutionary
Thought Develop?

Early biological thought did not include the
concept of evolution

Pre-Darwinian science was heavily influenced
by theological ideas, maintaining that all
organisms were created simultaneously by
God, and that each distinct life-form was
permanently fixed and did not change over
time
 Plato
(427–347 B.C.) proposed that each object on
Earth was merely a temporary reflection of its
divinely inspired “ideal form”
14.1 How Did Evolutionary
Thought Develop?

Early biological thought did not include the
concept of evolution (continued)

Pre-Darwinian science was heavily influenced
by theological ideas, maintaining that all
organisms were created simultaneously by
God, and that each distinct life-form was
permanently fixed and did not change over
time (continued)
 Aristotle
(384–322 B.C.) arranged all organisms on
a linear scale of increasing complexity (the “ladder
of Nature”)
Figure 14-1 Aristotle’s Ladder of Nature
Humans
Mammals
Birds
Reptiles and amphibians
Whales and porpoises
Fish
Squids and octopuses
Lobsters, crabs, etc.
Snails, clams, etc.
Insects, spiders, etc.
Jellyfishes, sponges, etc.
Higher plants
Lower plants
Inanimate matter
14.1 How Did Evolutionary
Thought Develop?

Exploration of new lands revealed a
staggering diversity of life
Europeans were often accompanied by
naturalists who observed and collected plants
and animals of previously unknown lands
 By the 1700s observations and collections
accumulated by naturalists revealed the true
scope of life’s variety
 The number of species was far greater than
expected

14.1 How Did Evolutionary
Thought Develop?

Exploration of new lands revealed a
staggering diversity of life (continued)

Revelation of the discoveries led 18th-century
naturalists to take note of fascinating patterns
 Geographic
areas possessed their own sets of
species
 Some species closely resembled one another yet
differed in some characteristics
 To some naturalists, these patterns seemed
inconsistent with the idea that species were fixed
and unchanging
Figure 14-2 A timeline of the roots of evolutionary thought
Buffon
(species created, than evolve)
Hutton
(gradual geologic change)
Lamarck
(mechanism of species change)
Cuvier
(successive catastrophes)
Smith (sequence of fossils)
Lyell (very old Earth)
Darwin
(evolution, natural selection)
Wallace (evolution, natural selection)
1700
1750
1800
1850
1900
Time line

Work on time line activity
14.1 How Did Evolutionary
Thought Develop?

A few scientists speculated that life had
evolved

George Louis LeClerc (Comte de Buffon;
1707–1788)
 Suggested
that the original creation provided a
relatively small number of founding species
 Species changed over time through natural
processes
14.1 How Did Evolutionary
Thought Develop?

Fossil discoveries showed that life has
changed over time

Fossils are the preserved remains or traces
of organisms that had died long ago
 Fossils
were the petrified remains of bones, wood,
shells, or their impressions left in mud
 Other fossils included preserved traces such as
tracks, burrows, pollen, eggs, and feces
Figure 14-3 Types of fossils
eggs in nest
fossilized feces
(coprolites)
bones
footprint
skin
impression
14.1 How Did Evolutionary
Thought Develop?

Fossil discoveries showed that life has
changed over time (continued)

Significance of fossil distribution
 The
British surveyor William Smith (1769–1839),
who studied rock layers and the fossils embedded
in them, recognized that certain fossils were
always found in the same layers of rock
14.1 How Did Evolutionary
Thought Develop?

Fossil discoveries showed that life has
changed over time (continued)

Significance of fossil distribution (continued)
 The
organization of fossils and rock layers was
consistent with fossils across different areas

Fossil type A always found in a rock layer resting
beneath a younger layer containing fossil type B, which
is found rested beneath an even younger layer
containing fossil type C, and so on
14.1 How Did Evolutionary
Thought Develop?

Fossil discoveries showed that life has
changed over time (continued)

Scientists of the period discovered that fossil
remains showed remarkable progression
 Most
fossils found in the oldest layers were very
different from modern organisms
 The resemblance to modern organisms gradually
increased in progressively younger rocks

Many of the fossilized species were extinct, which means
no members of the species still lived on Earth
14.1 How Did Evolutionary
Thought Develop?

Fossil discoveries showed that life has
changed over time (continued)

Scientists concluded that
 Different
types of organisms had lived at different
times in the past
 This countered the view that species were created
at one time and did not change afterward
Figure 14-4 Different fossils are found in different rock layers
youngest
rocks
oldest
rocks
Trilobite
Seed ferns
Allosaurus
14.1 How Did Evolutionary
Thought Develop?

Some scientists devised non-evolutionary
explanations for fossils

To account for the existence of extinct species
while preserving the notion of a single
creation by God, Georges Cuvier (1769–
1832) proposed the theory of catastrophism
 The
Great Flood described in the Bible produced
layers of rock and destroyed many species,
fossilizing some of their remains in the process
 The organisms of the modern-day species are the
survivors of these catastrophes
14.1 How Did Evolutionary
Thought Develop?

Geology provided evidence that the Earth
is exceedingly old
Charles Lyell (1797–1875) challenged
Cuvier’s hypothesis of a world shaped by
successive catastrophes
 Lyell, building on the earlier thinking of
Hutton, considered the forces involved in
catastrophes and concluded no need to
invoke catastrophes to explain the finding of
geology

14.1 How Did Evolutionary
Thought Develop?

Geology provided evidence that the Earth
is exceedingly old (continued)
Lyell presented the idea of uniformitarianism
to explain that Earth’s landscape was
produced by past action of the same
geological processes observed today
 The acceptance of uniformitarianism by
scientists implied that Earth is ancient

14.1 How Did Evolutionary
Thought Develop?

Darwin and Wallace proposed a
mechanism of evolution
Darwin and Wallace independently proposed
that organisms evolved by natural selection
 Both presented papers to the Linnaean
Society in London in 1858
 Darwin published On the Origin of Species by
Means of Natural Selection in 1859

How Do We Know How Old a Fossil Is? 17-1
http://education-portal.com/academy/lesson/the-history-of-life-on-earth-timeline-and-characteristicsof-major-eras.html#lesson (cuts off after a while)
1.
2.
Relative Dating (before 20th century)
a. Law of Superposition - Fossils in deeper rock
layers were older than fossils found in shallower
rock layers
Absolute Dating (1896)
a. Radiometric dating – when the nuclei of
radioactive elements spontaneously break down,
or decay, into other elements
b. Each radioactive element decays at a different
rates
How Do We Know How Old a Fossil Is? 17-1
2. Radiometric dating (cont.)
a. Time it takes for half of a radioactive element’s
(isotope) nuclei to decay at a specific rate is called
half-life.
b. Half-life of Carbon-14 = 5,730 years
Half-life of Potassium-40 = 1.25 billion years
c. Can estimate how much time has passed by
measuring the proportion of decayed nuclei to
undecayed nulcei
Half-lives
256 14C atoms
at time 0
128 14C and
128 14N atoms
after 5,730
years or
1 half-life
64 14C and
192 14N atoms
after 11,460
years or
2 half-lives
32 14C and
224 14N atoms
after 17,190
years or
3 half-lives
Half-lives
16 14C and
240 14N atoms
after 22,920
years or
4 half-lives
8 14C and
248 14N atoms
after 28,650
years or
5 half-lives
Half-lives
4
14C
and
252 14N atoms
after 34,380
years or
6 half-lives
2 14C and
254 14N atoms
after 40,110
years or
7 half-lives
Half-lives
Proportion of Isotope Left vs. Half Lives
Proportion of isotope left
1
1/2
1/4
1/8
1/16
0
1
2
3
Half-lives
4
5
How Do We Know How Old a Fossil Is? 17-1
3.
4.
Hyphen notation of radioisotopes (element
symbol and mass number)
Examples: C-12, C-14, O-16, O-18
Carbon-14 dating – compare ratio of C-14 and C12 and use the ratio to determine age
ISOTOPE
Carbon-14
Uranium-235
Potassium-40
Uranium-238
HALF LIFE (years)
5,730
704,000,000
1,250,000,000
4,500,000,000
How Do We Know How Old a Fossil Is? 17-1
Sample Problem 1:
The half-life of Thorium-230 is 75,000 years.
If a scientist has 40.0g of Thorium, how
much will remain after 225,000 years?
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
How many half-lives have past?
225-75 = 150
150-75 = 75
75-75 = 0
3 half-lives have past
How much Thorium is left?
40/2 = 20g
20/2 = 10g
10/2 = 5g
5g of Thorium remaining after
225,000 years
2.
The half life of carbon-14 is 5,730 years. How long
will it take for ½ of the sample to decay?
1 half-life = 5,370years = ½ the sample decays
If a biologist has 64.0g of C-14, how long will it take
until 8.0g remain un-decayed?
64/2 = 32g
1 half-life
5,730 x 3 half-lives =
32/2 = 16g
1 half-life
17, 190 years
16/2 = 8g
1 half-life
3 half-lives
3.
Labs
Half life lab
 Fossil hunt

14.2 How Does Natural
Selection Work?

Darwin and Wallace proposed that life’s
diverse forms arose through the process
of descent with modification
Individuals in each generation differ slightly
from the members of the preceding
generation
 Over long time periods, small differences
accumulate to produce major transformations

A. LAMARCK

1. Inheritance of acquired traitscharacteristics developed during an
organisms' lifetime would be passed on to
offspring.
a. proved untrue because traits are
determined by genes.
 b. Law of use and disuse- the more an
organism uses some part, the more
developed it will became, the less used , the
weaker it becomes.

B.WEISMANN
1. Disproved Lamarck
A. cut off tails of mice and
mated them for 20
generations
i. all offspring had tails
C. Charles Darwin
1.
2.
3.
Theory of Natural Selection
Overproduction- more offspring produced
than can survive.
Competition- due to limited resources
Variation- differences between
individuals
4.
5.
6.
Adaptation- characteristics that helps an
organism to survive better in one
environment.
Natural selection- organisms with
beneficial adaptations survive and
reproduce
Speciation- over a very long period of
time new species form due to the
accumulation of adaption (finches)
Darwin
Darwin
He was born in England in 1809.
 Invalid mother died when he was 8 years
old.
 He had poor grades in school.
 Father was a doctor and wanted him to
become a doctor.
 He went to medical school, then tried to
become a clergyman. Neither worked.

Darwin
Met a botanist named Prof. Henslow
 1831 set sail on the Beagle as a naturalist.
 Was seasick most of the time.
 He started making collections of skins and
fossils
 Discovered band of seashells high up in
the mountains
 He began noticing differences in beaks of
finches on different islands.


3. Adaptive radiation- divergent evolution
One species occupies new environments and
creates a new species in each
 Darwin’s finches

Darwin
1836 Beagle returns – Darwin had
collected 1500 animals, 4000 species.
 Through transmutation –( name for
evolution he began studying horse and
pigeon breeding.
 1839 – Voyage of the Beagle was
published
 1842- wrote his theory of Evolution

Darwin
1859- Origin of Species was first published
 It was not well accepted.
 1871- The Descent of Man was published

The Beagle
Only 90 foot long, but carrying 74 people.
Travels of the Beagle
1. Types of Adaptations
adaptation- trait that improves
chances of survival in a
specific environment.
A. Structural
structural
– involve body of the
organism
A. webbed feet, wings
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

Work on proof of evolution lab
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
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

Work together in groups of two on amino
acid sequence lab.
II.Rates of Evolution
A. Gradualism- evolution occurs slowly
and continuously over time according to
Darwin.
 B. Punctuated equilibrium- species stay
the same for a long period of time then
there is a rapid-Gould and Eldrege


1. fossil record seems to support this, but no
evidence for how such change could occur so
quickly can be found.
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 (b/c
of environment) but ancestors are very
different
a. natural selection of analogous
structures because of envir.
demands.
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

Frogs and the Venomous Path- read and
answer questions.
C. Protection
Camouflage- blends into environment
 Warning coloration- bright color warns of
its danger ( monarch )
 Mimicry- copying a successful strategy of
another ( viceroy)


Camouflage lab
Speciation

Formation of a species results from
isolation and adaptive radiation.

1. geographic isolation-population divided by
mountain, desert, river etc.
2. reproductive isolation – two groups cannot
interbreed successfully.
 Different courtship behavior, mating times,
mating calls
 Incompatible sex organs
In the struggle for existence,
individuals with a suite of traits that
makes them better adapted to the
environment seem to leave more
offspring than poorly adapted
individuals. This is the essence of
“natural selection”.
Over time, rabbits
in general tend to
run faster that
their ancestors…
There is a lot of variation in a typical
population
Eduardo Kac
#
Low
Medium
High
In a given
population of
rabbits, some
run faster than
others and
escape
predators.
Their offspring
run fast too…
Speciation

The evolution of new species.
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
Types selection:

Normal- bell curve

Stabilizing selection- average chosen

Directional – extreme chosen

Disruptive – both extreme chosen leads to
speciation
B. Physiological

Physiological- involve metabolism
Ex: venom, insecticide
X X
X X
The few survivors
from the early
applications of the
insecticide are those
insects with genes that
enable them to resist
the chemical attack.
Only these resistant
individuals reproduce,
passing on their
resistance to their
offspring.
In each generation
the percentage of
insecticide-resistant
individuals increases.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Other Modern-day Examples of Natural
Selection and Evolutionary Change
Antibiotic Resistance (NEVER quit taking a
prescription of antibiotics before the bottle is
empty)
AZT resistance (now chemical cocktails are
required)
Peppered Moth and Air Pollution (moths become
speckled to blend into soot -covered trees)