Darwins Theory of Evolution Darwin Presents his Case

Darwin’s Theory of Evolution Darwin Presents his Case Chapter 15 -3

In 1858 another naturalist, Alfred Russel Wallace wrote an _________, Malaysia that essay describing his work in _______ summarized the same ideas Darwin _____ had been thinking about for 25 years!

Suddenly Darwin had incentive to publish the results of his work! In 1859 On the Origin of Species __________ evidence presented _______ and proposed a mechanism ____ for evolution that he called NATURAL SELECTION _________

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 ____,

WHAT IS DARWIN’S THEORY? GENETIC VARIATION is found _________ naturally in all populations

WHAT IS DARWIN’S THEORY? ___________ STRUGGLE FOR EXISTANCE means that members of each species must COMPETE ____ for food, space, and other RESOURCES _____.

WHAT IS DARWIN’S THEORY? Some organisms in a ____ population less likely to survive. are ____

WHAT IS DARWIN’S THEORY? SURVIVAL OF THE FITTEST ___________ organisms which are better adapted survive and to the environment will ______ reproduce passing on their _____. genes ____,

VOCAB Ability of an individual to survive ______ and reproduce in its specific ______ environment = fitness ______

VOCAB inherited characteristic that Any __________ of survival increases an organism’s chance _______ ADAPTATION = _______

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. How Does Evolution Really Work?

WHAT IS DARWIN’S THEORY? DESCENT WITH MODIFICATION ______________ suggests that each species has DESCENDED with ____, CHANGES ______, from other species over time. This idea suggests that all living TO EACH OTHER species are RELATED __________, and that all species, living and extinct, COMMON ANCESTOR share a _________.

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

ARTIFICIAL SELECTION WORKS In artificial selection, ______ NATURE provides the _____ variation through _____ and sexual _________ mutation reproduction and humans _______ select those traits that they find ______. useful EX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.

Breeds of Dogs Chihuahua – bred from Techichi of Mexico by Mayans, had religious significance Saint Bernard – bred by monks around 1050 A. D. to rescue travelers of mountain passes in the Swiss Alps between Italy and Switzerland Irish Wolfhound – bred in Ireland to hunt wolves and elk Dachshund – bred in Germany as early as the 15 th century to hunt badgers

______________ ARTIFICIAL SELECTION WORKS

How Do We Know Evolution Happens? 2. The Fossil Record – Fossils are the remains _________ of ancient organisms found in layers of rock in the Earth.

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.

Movement of Earth’s Crust Section 15 -2 Earthquakes and volcanoes cause uplifting of the layers of the Earth, taking the fossils along Sea level Fish die in the ocean and are covered in sediment. Over time and under increasing pressure, the remains becomes fossilized Go to Section: Sedimentary rocks form in horizontal layers. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers. As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. Fossils of marine fish found on the mountainsides of southwest Wyoming, which at one time was covered by an inland sea

TRANSITIONAL FOSSILS HAVE BEEN FOUND Scientific American; Dec 2005; Vol 293; p 100 -107

TIK-TAALIK Intermediate between fish and early tetrapods Fins have basic wrist bones and simple fingers Earliest fish with a neck Discovered by Neil Shubin and Ted Daeschler in 2004

Fossil record shows change over time SD dinosaur fossils

If Darwin’s theory is correct you would expect to find closely ______ related yet ________ different species living in a _____ geographic region as they spread into nearby habitats and evolve. That’s EXACTLY what we do see!

http: //www. newtonswindow. com/problem-solving. htm REMEMBER THE GALAPAGOS TORTOISES Intermediate vegetation Intermediate necks Little vegetation Long necks Lots of vegetation Short necks Tortoises adapted to different habitats as they spread from the mainland to the different islands. = DIVERGENT EVOLUTION = ADAPTIVE RADIATION

http: //images. encarta. msn. com/xrefmedia/aencmed/targets/illus/ilt/T 014608 A. gif GALAPAGOS FINCHES The _____ beaks of Galapagos finches have foods. adapted ______ to eating a variety _____ of _____

If Darwin’s theory is correct you would species also expect to find different ________ living in far ____ apart geographic regions but similar habitats becoming more ____ alike similar ecosystems as they adapt to _______. That’s EXACTLY what we do see!

Whales and sharks have a _____ similar body design different organisms even though they are very _______ (one is a fish; the other, a mammal) because they have _________ independently adapted to living in a _____ similar environment. = CONVERGENT EVOLUTION

Whales are closely related to wolves, but don’t look or act much like them = divergent evolution Conclusion: The pressure of the environment drives evolution Whales are distantly related to sharks, but look and act more like them = convergent evolution

Figure 15– 14 Geographic Distribution of Living Species Section 15 -3 Beaver and capybara are _______ closely-related species living in very ________ different environments, while beaver and musk-rat are ________ distantly-related _______ species living in a similar environment. ______ Differences between beaver and capybara show _____ divergent evolution, while similarities between beaver and muskrat. Go show to convergent _____ evolution. Section: Beaver NORTH AMERICA Muskrat Beaver and Muskrat Coypu Capybara SOUTH AMERICA Coypu and Capybara Differences between _______ closely-related muskrat and coypu divergent show _____ evolution, while similarities between distantly-related _______ capybara and coypu show convergent ______ evolution.

Structures 4. HOMOLOGOUS ___________

4. 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 _______.

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

4. Homologous Body Structures – homologous body structures Some ____________ 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.

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 _____

Why grow a tail and then lose it? HUMAN EMBRYO _________ has a tail at 4 weeks tail _________ Tail disappears at _________ about 8 weeks

Skinks are a type of lizard. In some species, legs have become so small they no longer _______ function ______ in walking. Why would an organism possess organs with ___ little or no function ________? One explanation: code is present to make the organ, but The gene ____ function has been lost through _______. change over time _________ If the organ is not vital to survival, then natural selection would not cause its elimination.

5. ___________ Similarities in Embryology Embryos of many animals with back____ bones are very similar.

It is clear that the same groups of undifferentiated cells develop in the _______ same order to produce the same tissues and organs of all vertebrates, evolved from a suggesting that they all _______ common ancestor ________. Image from: http: //io. uwinnipeg. ca/~simmons/16 cm 05/1116/16 anim 3. htm

Similarities in DNA 6. ________ Similarities DNA and in ____ PROTEIN ____ sequences suggest relatedness

Human- 46 chromosomes Chimpanzee- 48 chromosomes karyotypes suggest an Similar _____ evolutionary relationship __________.

PATTERN MATCHES 1. BANDING ____________ If you take the two smaller chromosomes apes have that we don’t, and place them banding end to end, the ___________ pattern is identical to the we #2 human chromosome __ have that they don’t ________.

IN MIDDLE 2. TELOMERES __________ Chromosomes have special sequences called telomeres _______ at their ends to protect the strands during replication.

2. TELOMERES IN MIDDLE Telomere sequences are the ends and found at _____ ALSO IN THE MIDDLE ___________ of human chromosome #2 suggesting it was made by fusing _____ two other chromosomes together. → → →

WHY DOES EVOLUTION MATTER NOW? Can see Natural selection happen 7. ______________ EX: Peppered Moths Typica Carbonaria There is a natural variation in populations of peppered moths. Typica form - lighter ________ Carbonaria form - darker __________

light colored form was the predominant form The ______ in England _______________. prior to the Industrial Revolution Around the middle of the 19 th century the ______ darker form began to appear. It was first reported in 1848. By 1895 98% of the moths in Manchester were the dark ____ variety. In recent years, the burning of cleaner fuels and Clean Air regulations has reduced the pollution there and the lighter ______ colored moths have increased in numbers.

7. ______________ Can see Natural selection happen EX: Changes in disease-causing microbes that produce new organisms and new _____. diseases Bird flu _______ HIV ___ Antibiotic-resistant tuberculosis _____________

PBS EVOLUTION VIDEO CLIPS Isn’t Evolution Just a Theory? Quick. Time Who was Charles Darwin? Quick. Time How Do we Know Evolution Happens? Quick. Time How Does Evolution Really Work? Quick. Time | Why Does Evolution Matter Now? Quick. Time Why is Evolution Controversial Anyway? Quick. Time