EVOLUTION 15 3 Charles Darwin In 1859 Darwin

EVOLUTION 15. 3

Charles Darwin

In 1859 Darwin Published __________ On the Origin of Species presented evidence and proposed a Mechanism for evolution that he called NATURAL SELECTION _________ http: //www. loc. gov/exhibits/world/images/s 125. jpg

• Early scientists • Hutton & Lyell- Earth is millions of years old – Process are the same today as then. • Lamarck- selective use and disuse not true – Acquired traits are passed to offspring not true – Species change over time. TRUE

• Evidence for Evolution • Fossil record • Comparative anatomy – Homologous – Analogous – Vestigial • Embryology (early development) • Molecular Comparison

• Darwin hypothesized • Organisms produce more offspring than can survive • Organisms struggle for existence • Those best adapted to environment will survive. • Traits are passed down to offspring. • Descent with modification

Variations in a population • Differences in the phenotypes – Same species, different size beak • Natural selection acts on these differences – Beaks that are successful at getting food Causes of differences: • Mutations – changes in DNA (mutagens cause changes) • genetic recombination (crossing-over in meiosis)

• Key in Evolution is ………. . • The organism that is best adapted to the environment, lives long enough to reproduce, passing on the trait to offspring.

Isn’t evolution just a theory? A theory is a well-supported ______, testable _______, explanation of phenomena that have occurred in the natural world, like the gravitational attraction theory of _________, cell theory and _______. atomic theory ____, http: //www. avgoe. de/Star. Child/DOCS/STARCH 00/questions/apple_falling. gif http: //sixthsense. osfc. ac. uk/chemistry/atomic_structure 2/atom. gif

WHAT IS DARWIN’S THEORY? ___________ STRUGGLE FOR EXISTANCE means that members of each species must COMPETE ____ for food, space, and other RESOURCES _____. http: //www. wasatchcomputers. net/gallery/elk_fight. jpg

WHAT IS DARWIN’S THEORY? Some organisms in a ____ population less likely to survive. are ____ http: //www. cartoonstock. com/newscartoons/cartoonists/rrs/lowres/rrsn 69 l. jpg

WHAT IS DARWIN’S THEORY? Over time, natural selection CHANGES in the results in ____ inherited characteristics of a POPULATION _____. increase a These changes ______ species’ fitness _____ in its environment.

WHAT IS DARWIN’S THEORY? SURVIVAL OF THE FITTEST ___________ organisms which are better adapted to survive the environment will ______ and reproduce passing on their _____. genes ____, http: //www. poster. net/bedard/bed 202. jpg

WHAT IS DARWIN’S THEORY? GENETIC VARIATION is found _________ naturally in all populations http: //www 3. nationalgeographic. com/animals/images/primary/zebra-herd. jpg

http: //www. cartoonstock. com/newscartoons/cartoonists/cga/lowres/cgan 170 l. jpg FITNESS= Ability of an individual to survive ______ and reproduce in its specific ______ environment

ADAPTATION= inherited characteristic that Any __________ chance of survival increases an organism’s _______ http: //www. wildlife-traps. com/skunks. html http: //www. atomtigerzoo. com/photos/images/20060421233733_duckfeet. jpg http: //www. 3 kitty. org/travelrama/Photos/123 -21 -4 x 6. jpg

EVIDENCE OF EVOLUTION: Artificial selection 1. ________ Fossil record 2. ________ Geographic Distribution 3. ________ Homologous structures 4. ________ Embryology 5. ________ DNA 6. ________ See Natural selection happen 7. ________

How Do We Know Evolution Happens? The layers of rock tell the history of the Earth while the fossils _____, _____ found within life the rock tell a history of ___. The fossils are thought same age as to be the ____ the rock they are found in.

Figure 15 -Homologous Body Structures Section 15 -3 Turtle Alligator Ancient lobe-finned fish Bird Mammal

Homologous Body Structures – Structures, like the limbs of vertebrates, look very _______, different but are made from the same bones because _____, they are made from the same clump of undifferentiated cells _______ embryo in the _______. Image from: http: //www. angelfire. com/ab 7/evolution 12/evolutionclues. html

Some ____________ homologous body structures vestigial and have no useful are _______ function even though they are still hipbones whales and present, like ____in tail and boa constrictors, or a ____ cecum (appendix) ________in humans. http: //www. txtwriter. com/backgrounders/Evolution/EVpage 12. html

Most mammals have a pouch between their small and large intestine that contains bacteria cecum to digest plants called a _____. In humans the cecum is shrunken and unused. appendix It is our _____ http: //www. medicalgeo. com/images/appendix. gif

Why would an organism possess organs vestigial organs? One explanation: The gene is present to make the organ but the function has been lost through changes over time. If the organ is not vital to survival, then Natural selection would not cause its elimination.

Evidence for evolution cont. : Embryology- development of an organism as an embryo.

Evidence for evolution DNA

Human- 46 chromosomes Chimpanzee- 48 chromosomes karyotypes suggest an Similar _____ evolutionary relationship __________. Human: http: //www. nationmaster. com/wikimir/images/upload. wikimedia. org/wikipedia/en/thumb/1/18/300 px-Human_karyogram. png Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

______________ Can see Natural selection happen EX: Changes in disease-causing microbes that produce new organisms and new _____. diseases Bird flu _______ HIV http: //www. hhmi. org/askascientist/images/hiv. gif Antibiotic-resistant tuberculosis _____________ http: //www. hipusa. com/e. Tools/webmd/A-Z_Encyclopedia/tuberculosis. jpg

• What causes variations? • Mutations – Radiation – toxins • Sexual Reproduction – Different combinations of genes during meiosis – Crossing over of chromosomes

• Rate of Evolution

• Cladogram: Links groups of organisms by showing evolutionary lines branched off from common ancestors.

• Which 2 are more closely related? 9. turtles, birds, sharks 10. lizards, crocodiles, snakes 11. amphibians, mammals, sharks 12. crocodiles, snakes, birds

• Evolution in action • Video