1. Life on Earth: The Theory of Evolution

2. What is a Theory  Video Segment 1  https://www.youtube.com/watch?v=85di EXbJBIk&list=PL5270149AB732F0FB&i ndex=1 https://www.youtube.com/watch?v=85di EXbJBIk&list=PL5270149AB732F0FB&i ndex=1 https://www.youtube.com/watch?v=85di EXbJBIk&list=PL5270149AB732F0FB&i ndex=1

3. Origin of Life  Before the 17 th century people believed in a process called spontaneous generation.  Living things could arise from non-living things.  Why did they think that?  If they would leave rotting meat out then maggot seem to appear so the meat must give rise to maggots. (NOT Exactly)

4. Experiments  In 1668, Redi proved spontaneous generation to be false  Meat and Flies  Spallanzani also preformed an experiment  2 broth flasks (boiled)  Problem: what happens to bacteria when you cook them?  1800’s, Louis Pasteur modified Spallanzani’s experiment  Used curved necked flask

5. Earth’s History  Earth is about 4.6 billion years old  No usable oxygen.  Anaerobic organisms.  The fossil evidence says they were most likely prokaryotes  Probably heterotrophs  Some may have also been autotrophs  Archaebacteria bacteria that uses chemosynthesis instead of photosynthesis

6. We need More Oxygen  Some relatives to cyanobacteria used photosynthesis  more oxygen is formed.  Some of this oxygen went into the upper atmosphere where it formed the ozone layer.  The ozone layer helps protect the earth from ultraviolet radiation that can damage DNA

7. More complex cells form  So we have prokaryotes that are aerobic and are not to complex  Endosymbiosis  The small invaders would give rise to mitochondria and chloroplasts  Mitochondria and chloroplast have their own circular DNA that is different from the cells DNA

8. Possible explanations for the things that have been observed. ???

9. Lamarck’s explanation  His hypothesis  Similar species descended from a common ancestor  His evidence  Fossil records  His reasoning  Acquired trait are passed on to offspring  Things passed on due to experience not genetic

10. “The Inheritance of Acquired Characteristics”  Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

11. Darwin and Wallace  About 50 years later, two scientists, Charles Darwin and Alfred Wallace, both came up with the same idea: natural selection  Natural selection: organisms that are best suited for their environment are able to reproduce hence passing on the favorable traits.

12. Charles Darwin  Darwin set sail on the H.M.S. Beagle (1831- 1836) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals.  On the Galapagos Islands, Darwin observed species that lived no where else in the world.  These observations led Darwin to write a book.  Video Segment 2 “Who is Charles Darwin”  https://www.youtube.com/watch?v=vmphlb RhLu8&list=PL5270149AB732F0FB&index =2 https://www.youtube.com/watch?v=vmphlb RhLu8&list=PL5270149AB732F0FB&index =2 https://www.youtube.com/watch?v=vmphlb RhLu8&list=PL5270149AB732F0FB&index =2

13. Darwin’s Two Theories  Descent with modification  Newer forms appearing in the fossil record are really modified descendants of older species  Modification by natural selection  Describes how evolution occurs  Environment affects populations, some organisms can cope and others cannot.  Adapting results in a change in the genetic make-up of the population (selective advantage)  Fitness is a single organisms contribution to change

14. Natural Selection  Individuals with favorable traits are more likely to leave more offspring better suited for their environment.  Example: English peppered moth (Biston betularia) Biston betulariaBiston betularia - light and dark phases

16. Natural Selection 1.All species produce offspring at a faster rate than food supplies can increase. 2.Except for identical twins, no two individuals are exactly alike. 3.In each generation, more individuals are produced than can survive. 4.Individuals that possess certain traits have an advantage over those that do not.

17. Natural Selection 5.Geographical isolation may lead to the formation of a new species. 6.The environment determines whether a trait is beneficial. 7.Traits are inherited and passed on to the next generation. 8.Over time, successful variations accumulate in a population, and a new species may appear. https://www.youtube.com/watch?v=ewtw_nZUIDQ&list=PL52701 49AB732F0FB&index=3

18. Darwin’s key idea: Natural Selection **Four tenants of natural selection** 1.Genetic Variation: Variety of traits exist. These variations are called alleles. Example: blue eyes, brown eyes. 2.Overproduction of offspring: Organisms produce more offspring than can survive 3.Struggle for existence (Survival of the fittest): Organisms compete over resources to survive and reproduce. Organisms best suit for environment survive to pass on genes. 4.Differential survival & reproduction: over time, traits of successful reproducers become more common

19. Evidence of Evolution 1.Biogeography – Plate Tectonics 2.Fossil Record 3.Adaptations 4.Comparative Anatomy Vestigial StructuresVestigial Structures Homologous/Analogous structuresHomologous/Analogous structures 5.Comparative embryology 6.Molecular biology

20. How does it work  Video Segment #4: How Does Evolution Really Work?  https://www.youtube.com/watch?v=xkw RTIKXaxg&index=4&list=PL5270149AB 732F0FB https://www.youtube.com/watch?v=xkw RTIKXaxg&index=4&list=PL5270149AB 732F0FB https://www.youtube.com/watch?v=xkw RTIKXaxg&index=4&list=PL5270149AB 732F0FB

21. Biogeography Geographical distribution of species. Organisms tend to arise in areas where similar organisms lived in the past

22. Comparative Anatomy: Structural similarities link related species

23. Vestigial Structures  Features that are not used by the organism but may have been useful to ancestors  Example:  In humans: tailbone, appendix  In whales: pelvic bone and four chambered stomach  In snakes: pelvic bone, limb bones

24. Homologous structures Homologous: structures that are similar because of common ancestry and develop similarly

25. Homologous and embryo  Complete the homologous and embryo color sheet following the teacher directions.

26. Comparative embryology Study of structures that appear during embryonicdevelopment.

27. Molecular biology  DNA and proteins (amino acids)  Mutations are changes in the DNA.  Gene flow is any movement of genes from one population to another.  Sexual Reproduction

28. Convergent Evolution  Species from different evolutionary branches may come to resemble each other even though they are not closely related  Example: 1.Ostrich (Africa) & Emus (Australia). 2.Sidewinder (Mojave Desert) & Horned Viper (Middle East Desert) 3. Sharks and Dolphins

29. Divergent Evolution  2 or more species or related population become more and more dissimilar  Can result in a new species  Types:  Adaptive radiation: related species evolve from a single ancestral species (Galapagos finches)  Artificial selection: breeding organisms for specific trait (dogs)

30. Writing  Under your notes  Write me a paragraph in detail describing what you have learned so far about evolution.  We have done dot lab, checks lab, evidence of evolution, theory of evolution, lamark versus Darwin.

31. Mechanisms of Change 1.Mutation  A change in the DNA sequence. (1 in 100,000) leads to new traits. (1 in 100,000) leads to new traits. Some traits will be advantageous to the species. 2.Migration  Movement of individuals form one population into another.  Can alter the genetic characteristics of a population.

32. Mechanisms of Change 3.Nonrandom Mating- controls the genes  When individuals mate with one another more or less frequently: example inbreeding. 4.Selection  Artificial Selection – individuals breed organisms for specific traits.  Natural Selection - environment dictates Which traits are needed to survive. to survive.

33. Mechanisms of Change 5.Genetic Drift  Random loss of alleles. Small population a person does not reproduce.  Founder effect – one or a few individuals migrate and become an isolated population with distinct genotypes.  The population splits due to migration events  Bottle neck – restrictions in genetic variability due to flooding or natural disasters.  The population splits due to natural disasters

34. Speciation (How do we get a new species?)  Usually involves successive change  Local populations of a species become isolated and more specialized (adapted)  Natural selection acts to keep them specialized (different from the larger population)  Populations of a species must become reproductively isolated in order to develop into new species.

35. Mechanisms of Change  Complete the coloring sheet Gene Flow  Be sure to read and highlight  Color neatly  Complete the coloring sheet Genetic Drift  Be sure to read and highlight  Color neatly