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TRANSCRIPT
EVIDENCE
FOR
EVOLUTION
FOSSIL RECORD
• FOSSILS: Any past evidence that has been
preserved in the earth's crust
• FOSSILS indicate that LIVING ORGANISMS
on the earth have changed markedly over
millions of years. However, the modern
organisms are not completely different from
that of the past.
• PRESERVED features of present-day plants
and animals clearly link them to EXTINCT
ORGANISMS in the past: they have simply
been modified from their ancestral forms.
• The fossil record is very INCOMPLETE
due to the rare conditions that allow the
formation of fossils and that expose
fossil-bearing STRUCTURES.
• However, in many cases fossils have
been found that show the TRANSITION
from one major group of organisms to a
new group, such as from reptiles to birds.
(EX - Archaeopteryx)
ARCHAEOPTERYX
DETERMINIG AGE OF FOSSILS
RELATIVE DATING: Fossil age is
determined from it's position in the rock
• LAW OF SUPERPOSITION:
Younger layers of rock are deposited
on top of older layers.
• The layers of SEDIMENTARY rock
are called STRATA
• Does NOT give an exact AGE of the
fossil
CLOSER TO TOP
IS MORE RECENT
DEEPER DOWN
IS OLDER
RADIOMETRIC DATING: Analyze the amount of certain
radioactive elements found in the
fossil or surrounding rocks.
• Living organisms have a FIXED
percentage of radioactive elements
within them while living.
• Radioactive elements have a
specific decay rate at which they
break down known as the
HALF LIFE
• Example: Potassium 40
has a half life of:
1.3 BILLION years
i.e. it will take 1.3 million
years for half of the
"Potassium 40" to break
down into "Argon 40"
• This method is very
ACCURATE and gives
an exact age of the fossil.
• ORGANISMS FROM AREAS THAT ARE NEAR
BY DISPLAY SIMILAR CHARACTERISTICS
EVEN THOUGH ENVIRONMENTS MIGHT BE
VERY DIFFERENT.
BIOGEOGRAPHY
? ? WHO IS THE MARA MORE CLOSELY RELATED TO?
Similar
environment,
but found in
distant locations
Different
environment,
but originating
from nearby
location
COMPARATIVE ANATOMY The COMPARISON of body structures in
different species
HOMOLOGOUS STRUCTURES: • Functionally are very DIFFERENT
(what they are used for)
• Anatomically are very SIMILAR
due to COMMON ANCESTORY
(how they are put together)
• example: compare the human are with that
of a whale, cat, horse, bat, bird, etc…
- HUMEROUS
- RADIUS
- ULNA
- CARPALS
- METACARPALS &
PHALANGES
COMPARATIVE ANATOMY
VESTIGIAL STRUCTURES • Structure currently serves no FUNCTION in
the organism
• Structure was INHERITED from an ancestor that had a purpose for it
Examples:
• PELVIC BONES IN
• WHALES & SNAKES
• HUMAN APPENDIX
• KIWI WINGS
COMPARATIVE ANATOMY ANALAGOUS STRUCTURES:
• Functionally are very SIMILAR
• Anatomically are very DIFFERENT
• NOT due to common ancestry
• Functionally similar features can evolve
independently in similar environments
An Application of the Evidences
of the Fossil Record and
Homologous Structures:
Where did whales come from??
COMPARATIVE ANATOMY
EMBRYOLOGY
Similarites
In Early
Development
In 1998 we rewrote page 283 of the 5th edition of Prentice-Hall Biology to better
reflect the scientific evidence. It is NOT based on Haekel’s 1874 drawings.
Our books now contain accurate drawings of the embryos made from detailed
photomicrographs: Authors - Ken Miller & Joe Levine
These photographs are absolutely accurate and have been taken at similar stages of development.
Fish embryo
Chicken embryo
Pig embryo
Human embryo
EMBRYOLOGY
Let’s take a closer look at the
similarities found in vertebrate
embryonic development…
COMPARATIVE BIOCHEMISTRY • Further evidence of evolution comes
from examining the similarity among organisms in their GENETIC makeup
• The UNIVERSALITY of the Genetic code is STRONG evidence that ALL life is RELATED
• MOST RECENT FORM
OF EVIDENCE
COMPARATIVE BIOCHEMISTRY
HUMANS AND CHIMPANZEES
SHARE OVER 98% IDNETICAL DNA
CENSORED
COMPARATIVE BIOCHEMISTRY
PROTEIN SYNTHESIS
CYTOCHROME C:
ALMOST ALL LIVING
THINGS HAVE IT
(PLANTS, ANIMALS,
MICROORGANISMS)
COMPARING THE A.A.
SEQUENCES CAN
SHOW HOW CLOSELY
RELATED 2 SPECIES
ARE
ARTIFICIAL SELECTION • PEOPLE HAVE BEEN ARTIFICIALLY
SELECTING DOMESTICATED PLANTS
AND ANIMALS FOR THOUSANDS OF
YEARS
• EX – BROCCOLI & BRUSSEL SPROUTS
EX – DOG BREEDS
WOULD ANY OF THESE BREEDS
EXIST WITH OUT ARTIFICIAL
SELECTION BY HUMANS?
http://www.orlandosentinel.com/community/news/tavares/orl-littledog2707apr27,0,6506791.story
Gibson – the tallest dog in the world
Tiny Dancer – the smallest dog in the world