Transcript theory of evolution - River Dell Regional School District

THEORY OF EVOLUTION
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
 Due Thursday

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)