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EVIDENCES OF EVOLUTION“NOTHING IN BIOLOGY MAKES SENSE EXCEPT IN THE LIGHT OF EVOLUTION”
EVIDENCES OF EVOLUTION
• EVOLUTION HELPS EXPLAIN THE UNITY OF LIFE, WHICH BASICALLY STATES THAT ALL LIFE CAME
FROM A COMMON ANCESTOR
• EVOLUTION HELPS EXPLAIN THE DIVERSITY OF LIFE – DIVERSITY IS VARIETY OF SPECIES FOUND IN
A GIVEN AREA.
• MAJOR EVIDENCE THAT ALL SPECIES EVOLVED FROM A COMMON ANCESTOR:
• ALL SPECIES SHARE DNA/RNA AS A WAY OF STORING AND TRANSFERRING GENETIC MATERIAL
• ALL SPECIES SHARE THE SAME 20 AMINO ACIDS THAT BUILD UP THEIR PROTEINS
• ALL SPECIES USE THE SAME TRIPLET CODE (CODON) TO CODE FOR BUILDING AMINO ACIDS
THE THEORY OF EVOLUTION• CHANGE OVER TIME
• PEOPLE USED TO THINK THAT SPECIES DID NOT CHANGE
• DARWIN WAS NOT THE FIRST PERSON TO COME UP WITH THE THEORY OF EVOLUTION
• MANY SCIENTISTS CAME UP WITH THE IDEA THAT SPECIES CHANGE, THEY JUST DIDN’T KNOW HOW
JOHN BAPTISTE LAMARCK
• FRENCH BIOLOGIST (1744 – 1829)
• LAMARCK KNEW THAT SPECIES CHANGED, JUST HAD THE WRONG MECHANISM
• HE PROPOSED LAMARCKIAN INHERITANCE
• USE AND DISUSE OF ACQUIRED TRAITS
LAMARCKIAN INHERITANCE
• IF AN ORGANISM USED A SPECIFIC TRAIT A LOT, THEN THAT
TRAIT WAS AUTOMATICALLY PASSED ON TO ITS OFFSPRING
• WORKED OPPOSITE AS WELL – IF AN ORGANISM DID NOT
USE A SPECIFIC TRAIT, THEN THAT TRAIT WAS NOT PASSED ON
TO ITS OFFSPRING
• HE USED GIRAFFE’S TO PROVE HIS THEORY
• SINCE THEY KEPT STRETCHING THEIR NECKS TO REACH HIGH
LEAVES, GIRAFFES NECKS BECAME PROGRESSIVELY LONGER
FROM GENERATION TO GENERATION
• DRIVEN BY NEED
LAMARCKIAN INHERITANCE
• IF LARMARCK’S THEORY WAS TRUE THEN
ARNOLD SCHWARZENEGGER WOULD
HAVE PASSED LARGE MUSCLES ON TO HIS
CHILDREN
• RIGHT??????
LAMARCKIAN INHERITANCE
• WRONG!!!!!
• SCHWARZENEGGER’S OFFSPRING
• HIS CHILDREN DID NOT AUTOMATICALLY INHERIT
LARGE MUSCLES JUST BECAUSE THEIR FATHER USED
HIS A LOT
LAMARCKIAN INHERITANCE
• WE CAN TRY TO APPLY THE SAME THEORY TO
SOMEONE WHO IS MISSING A LIMB
• SINCE THIS GIRL IS MISSING AN ARM, ACCORDING
TO LAMARCKIAN INHERITANCE HER CHILDREN
WOULD AUTOMATICALLY NOT HAVE AN ARM….
• AGAIN WRONG!
SO WHO WAS RIGHT?
• OVER TIME LAMARCK’S THEORY WAS PROVEN WRONG
• IT WAS LATER REPLACED BY DARWIN’S THEORY ON NATURAL SELECTION
CHARLES DARWIN
• ENGLISH MINISTER TURNED NATURALIST (1809 – 1882)
• SAILED AROUND THE WORLD IN A SHIP CALLED THE BEAGLE
• CONSIDERED THE “FATHER OF EVOLUTION”
• HE CAME UP THE THEORY OF NATURAL SELECTION THAT IS WIDELY ACCEPTED STILL TODAY
• HE PUBLISHED IT IN HIS BOOK CALLED THE ORIGIN OF SPECIES IN 1859
EVIDENCES OF EVOLUTION
• DARWIN USED THE FOLLOWING EVIDENCES TO PROVE HIS THEORY OF EVOLUTION
• MORPHOLOGIES
• FOSSILS
• EMBRYOLOGY
• COMPARATIVE ANATOMY
MORPHOLOGIES
• THE FORM AND STRUCTURE OF ORGANISM’S TRAITS DEPENDING
ON THEIR ENVIRONMENT
• EXAMPLE:
• FINCHES ON THE ISLANDS OF THE GALAPAGOS HAVE DIFFERENT
BEAK SHAPES FOR THE FUNCTION OF EATING DIFFERENT FOOD
ITEMS AVAILABLE ON THEIR ISLAND.
FOSSILS
• STUDY OF PRESERVED REMNANTS OR IMPRINTS OF ORGANISMS
• TRANSITIONAL FOSSILS
• EXPLAIN LINKS BETWEEN DIFFERENT GROUPS
• EXAMPLES –
• TIKTAALIK IS AN ORGANISM THAT SHOWS US HOW ORGANISMS TRANSITION FROM WATER TO LAND.
• ARCHROPTERYX IS A TRANSITIONAL FOSSIL THAT SHOWS US HOW BIRDS EVOLVED FROM REPTILES.
Tiktaalik
Archeopteryx
FOSSILS
• LAW OF SUPERPOSITION
• STATES THAT RECENT FOSSILS WILL BE FOUND AT THE TOP
LAYERS, WHILE OLDER FOSSILS WILL BE FOUND ON THE
BOTTOM LAYERS
FOSSILS
• SEQUENTIAL TRANSITIONAL FOSSILS
• SHOWS HOW ONE ORGANISM PROGRESSED OVER TIME
FOSSILS
• LIVING FOSSILS (GHOSTS OF EVOLUTION, ANACHRONISMS)
• LAST OF THEIR LINEAGE OR “HOLDOVER” FROM EARLIER TIMES
• EXAMPLES –
• PLATYPUS – THE LAST OF THE MAMMALS TO STILL LAY EGGS
• HORSETAILS AND AVOCADOS – AMONG THE OLDEST PLANTS LIVING TODAY
EMBRYOLOGY
• COMPARING EMBRYOS OF DIFFERENT ORGANISMS FOR
SIMILARITIES SHOWING THE DEVELOPMENTAL PROCESS IS THE
SAME IN DIFFERENT SPECIES
• THIS PROVES THAT CERTAIN ORGANISMS DESCENDED FROM A
COMMON ANCESTOR
• EXAMPLE –
• ALL VERTEBRATES HAVE GILL SLITS AND A TAIL BONE IN THE
EMBRYONIC STAGE. IN SOME ANIMALS THESE TURN INTO
ACTUAL GILLS, IN OTHERS THEY TURN INTO EAR BONES
COMPARATIVE ANATOMY
• COMPARING THE STRUCTURE OF
DIFFERENT ORGANISMS TO SHOW
COMMON ANCESTRY
• TYPES –
• HOMOLOGOUS STRUCTURES
• ANALOGOUS STRUCTURES
• VESTIGIAL STRUCTURES
HOMOLOGOUS STRUCTURES
• SAME STRUCTURE, DIFFERENT FUNCTION
• DUE TO A COMMON ANCESTOR
• CAUSED BY DIVERGENT EVOLUTION
• SPECIES THAT WERE ONCE SIMILAR EVOLVE DIFFERENTLY DUE TO
DIFFERENT ENVIRONMENTS
ANALOGOUS STRUCTURES
• SAME FUNCTION, DIFFERENT STRUCTURE
• DUE TO DIFFERENT ORGANISMS NEEDING THE
SAME FUNCTION
• CAUSED BY CONVERGENT EVOLUTION
• SPECIES THAT WERE ONCE VERY DIFFERENT
EVOLVE TO HAVE SIMILAR TRAITS
VESTIGIAL STRUCTURES
• STRUCTURES PRESENT IN MODERN ORGANISMS THAT
NO LONG FUNCTION, BUT FUNCTIONED IN ANCESTRAL
ORGANISMS
• EXAMPLES IN HUMANS –
• APPENDIX
• WISDOM TEETH
• TAIL BONE
OTHER EVIDENCES OF EVOLUTION
• THE FOLLOWING EVIDENCES HAVE SINCE BEEN ADDED TO DARWIN’S
• BACTERIAL RESISTANCE
• MOLECULAR DATA
• ENDOSYMBIOSIS
• THESE WERE NOT KNOWN IN DARWIN’S TIME BUT DUE TO THE TECHNOLOGY WE HAVE TODAY
WE CAN NOW HELP FURTHER PROVE DARWIN’S THEORY
BACTERIAL RESISTANCE
• AS WE USE ANTIBIOTICS MORE, BACTERIA ARE EVOLVING TO BECOME RESISTANT TO THEM
• THE BACTERIA SURVIVE AND CONTINUE TO MULTIPLY CAUSING US TO BECOME MORE SICK
MOLECULAR DATA (MOLECULAR BIOLOGY)
• FINDING THE RELATIONSHIPS IN THE AMINO ACIDS AND DNA OF DIFFERENT SPECIES TO SEE
HOW SIMILAR OR DIFFERENT THEY ARE FROM EACH OTHER
WHICH PRIMATE IS MOST CLOSELY RELATED TO
THE CHIMP?
• COMPARE THE AMINO ACIDS OF THE CHIMP TO
EACH OF THE OTHER ANIMALS.
• THE ANIMAL WITH THE LEAST AMOUNT OF
DIFFERENCES FROM THE CHIMP WILL BE THE
MOST CLOSELY RELATED
WHICH PRIMATE IS MOST CLOSELY RELATED TO
THE CHIMP?
• GORILLA AND CHIMP HAVE THE SAME AMINO
ACIDS
ENDOSYMBIOSIS
• SMALL BACTERIA CELLS ENTERED LARGER BACTERIA
CELLS. THESE SMALLER CELLS BEGAN TO LIVE INSIDE
AND BENEFIT THEIR HOST CELL, EVENTUALLY
BECOMING CELLULAR ORGANELLES
• EXAMPLES –
• MITOCHONDRIA
• CHLOROPLASTS
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