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Darwin vs. Lamarck
Jean-Baptiste LaMarck

French, Early 1800’s
Theory of
Inheritance of
Acquired Characteristics

Two main points…
1. Principle of Use & Disuse:
•
Most used body structures develop, unused
structures waste away
2. Inheritance of Acquired
Characteristics:

Once the structure is modified, the new trait
can be inherited (passed to offspring)
Explain the picture below as if you were
LaMarck…
Why we don’t believe him…
Experiments: show that changes that
occur in an animal’s life are not passed on to its offspring
Genetics
:
Gregor Mendel discovered that
traits are passed down through GENES (which aren’t
affected by the outside world in that way)
Charles Darwin
“The Father of Evolution”
1831- sailed on the HMS Beagle to the
Galapagos Islands.
 Studied many species of finches.
 Published book in 1845:
– “On the Origin of Species by
Natural Selection”

Darwin’s Theory of Evolution
(don’t copy all this it’s on your handout) 
“Natural Selection”
“Survival of the Fittest”
Four main points…

1. More organisms are produced than can
survive…leads to COMPETITION OVER
RESOURCES

Ex’s of resources…
–
Water
– Food
– Habitat
– Mates
2. Individuals within a population vary,
and some of these traits are heritable.
3. Some variations are FAVORABLE
(increase chances for survival/ reproduction)


Male vs. Female
Cardinals
Male color attracts
female= reproductive
advantage
1. Better adapted individuals survive
and reproduce


These are the individuals that will pass on
their genes to the next generation.
This can change the GENE POOL:
–
Includes all the genes of every reproductive
member of a population
What The theory of evolution IS NOT!!!




It does NOT occur in INDIVIDUALS…only
populations!
It does NOT happen quickly…the Earth has a
Looooooong history!
It does NOT explain how life came to be on
Earth, just how it evolved after it was here.
It does NOT have any driving force except
the competition for limited resources.
Darwin’s Finches…p 558

Illustrate SPECIATION: when a species
breaks into two (or more)
–
The organisms in the two species can no longer…


INTERBREED
What could cause this to happen?
–
–
–
Geographic barriers
Occupy a new niche/habitat
Reproductive Isolation-
What would Darwin say to explain why
giraffe’s have such long necks?


See pg. 553
Evolution- “Change Over Time”

All of the changes that have occurred in living things since the
beginning of life on Earth
History of the Earth
700 million years ago…



Evolution occurs over MANY generations
Evolution occurs within POPULATIONS
(NOT individuals)
Evolution involves genetic changes in a
SPECIES
–
(Members of a species interbreed to produce
healthy, fertile offspring)
Evidence for Evolution
FOSSIL EVIDENCEProvides TRANSITIONAL LINKS
Archaeopteryxlinks reptiles and birds
Anatomical Evidence
HOMOLOGOUS
STRUCTURES
ANALOGOUS
STRUCTURES
structures that are similar
because they were inherited from
a COMMON ANCESTOR
similar in function, but NOT
inherited from a common
ancestor
NOTE: similar structure, but NOT always
function!
NOTE: similar FUNCTION, but not
STRUCTURE
More Anatomical Evidence:
Vestigial Structures
Vestigial Structures are
undeveloped structures
that were functional in
some ancestor, but are
no longer needed in that
organism.
EMBRYOLOGYsuggests common ancestors
BIOGEOGRAPHICAL EVIDENCE

When we study the distribution of plants and animals on the planet,
we notice:
– Animals evolved differently in each of the biogeographical regions
– We see evidence that as the continents drifted, organisms were
separated and evolved.
BIOCHEMICAL EVIDENCE

Almost all living things use the same
biochemical molecules
–

DNA, Protein, ATP
Vast diversity came about by only slight
differences in the same genes
–
The more closely “related” the organisms are, the
more similar their DNA
Other Evidence…

1. Mimicry and Camoflauge

2. Antibiotic Resistance