Evolution

1. Evolution

2. Key Points • Heritable characteristics increase or decrease an organisms chance of survival • Evolution is the change of the genetic makeup of a population over time • More closely related organisms have more closely related DNA and proteins • Many organisms have similar structures, and many organisms develop similarly

3. Key Points • Mutations that lead to evolution occur randomly • All species on earth are related by a common ancestor • The fossil record shows organisms that are no longer alive • Environmental pressures, genetic drift, mutation and competition for resources lead to evolution

4. How did life on earth begin? • There are many theories • Information about early earth comes from rocks • The earth is ~4.6 billion years old • The oldest clues about life on earth are ~3.5 billion years old

5. Fossils • Fossils are preserved evidence of organisms • 99.9% of all organisms are extinct • Very few organisms become fossilized • Many fossils are casts • Minerals fill in the areas where the organism was

6. Dating Methods Relative Dating • A technique where items (rocks or fossils) are dated by comparing the soil layers • The Law of Superposition • Sedimentary rock is deposited in layers • Older layers are deeper • Newer layers are on top • Explain the picture?

7. Dating Methods Radiometric Dating • Uses radioactive isotopes to date rocks or organic material • Uses the half life of the isotope • Carbon-14 • Decays to Nitrogen-14 • Half life is 5730 years • Can date organisms up to 50,000 years • Potassium-40 • Used to date older items • Can only be used to date rocks • Half life is 1.3 Billion years

8. Geologic Time • Represents major geologic events

9. Spontaneous Generation-A Hypothesis • Spontaneous generation- life arises from no life • Francisco Redi’s experiment • Redi’s experiment opposes the hypothesis

10. Biogenesis- a theory • Biogenesis- life arises from life • Louis Pasteur – biogenesis is true for microorganisms

11. Origins of Life • Simple organic molecule formation • Organic molecules could be synthesized by simple reactions • UV light from the Sun and lightning may have been the primary energy source

12. Miller and Urey • Simple organic molecules are made from inorganic molecules • Conditions were like that of early earth

13. Prokaryotes evolved first • Archea most closely resemble earth’s first life • They are autotrophs, energy does not come from the sun, they do not need oxygen • Photosynthesizing prokaryotes evolved next • Oxygen was just a byproduct • Eukaryotes evolved by prokaryotes developing symbiotic relationships

14. Endosymbiont Theory

15. Darwin & Natural Selection • Darwin was a naturalist on the HMS Beagle • He was also a companion to the captain • He collected biological samples • Darwin collected many birds, mockingbirds and finches on the Galapagos Islands • Each island had similar birds, but they were slightly different

16. Artificial Selection and Natural Selection • Humans could changes species such as dogs by artificial selection • Darwin’s Hypothesis • New species could appear gradually through small changes in ancestral species

17. Natural Selection • Individuals in a population show variation • Variations are inherited • Organisms have more offspring than can survive on the available resources • Variations that increase reproductive success will have a greater chance of being passed on

18. Support for Evolution • Fossils • Fossils show species that lived long ago • Ancient species share similarities with living species Glyptodont Armadillo

19. Support for Evolution • Derived traits: newly evolved features that do not appear in common ancestors • Feathers • Ancestral traits • More primitive features that do appear in ancestral forms

20. Homologous Structures • Anatomically similar structures inherited from a common ancestor • Structures are used for different purposes

21. Vestigial Structures • Structures that are reduced in form • They are useful in related organisms • Features of ancestors that are no longer useful will become smaller or lost over time

22. Analogous Structures • Structures used for the same purpose but are not from a common ancestor

23. Comparative Embryology • Vertebrate embryos look very similar as embryos • Develop differently as they get older

24. Comparative Biochemistry • Common ancestry can be seen in metabolic molecules • DNA • Amino acid sequences • More closely related organisms have similar sequences

25. How Organisms Evolve

26. Genetic Drift • Change in allele frequency • Caused by chance • Seen in small populations

27. Founder Effect Population Bottleneck The population almost goes extinct A few surviving members survive and reproduce • A small sample of a population emigrate to a new area • Alleles that were uncommon in the parent population become popular

28. Gene Flow Nonrandom Mating • Immigration and emigration • Increases variation within a population • Promotes inbreeding • Can cause alleles frequency to change • Female is usually choosey • Male usually displays traits

29. Types of Selection • The best suited individuals survive • Derive a situation that could cause each graph.

30. Human Evolution • What is a primate (Ape) • Manual dexterity • Flexible bodies • Limber shoulders and hips • Large Brain • Can solve problems • Social • Newborns dependent on mother • Have fewer offspring • Are you an ape?

32. Humans • Bipedalism- changing environment • Large Brain- evolved after bipedalism