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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