EVOLUTION

1. EVOLUTION Nancy G. Morris Volunteer State Community College

2. Theory of Evolution The theory of evolution states that: life arose from random non-living chemical processes that took place in the ancient oceans. mutations and natural selection have brought great change in organisms. Life has become more diverse and complex.

3. THE ORIGIN OF LIFE Life on earth originated approximately 3.5 billion years ago.

4. THE ORIGIN OF LIFE The theory states that abiotic chemical processes occurring on the early earth produced basic precursors leading to the building blocks of life. In 1953, Miller and Urey achieved synthesis of small organic molecules from abiotic compounds like those thought to exist on the early earth.

5. THE ORIGIN OF LIFE They produced amino acids and other building blocks by electrically sparking atmospheric gases that probably existed on the early earth.

6. Comparative Anatomy The bone types in the limbs of amphibians, reptiles, birds, and mammals is very similar. This suggests common ancestry.

7. THE ORIGIN OF LIFE An organic soup -- a mixture of all sorts of carbohydrate, amino acids, nucleotide, and lipid molecules --accumulated in the early oceans as atmospheric gases reacted. Energy was supplied by lightning and UV radiation from the sun.

8. THE ORIGIN OF LIFE Laboratory simulations of early earth conditions have produced organic polymers such as polypeptides. Amino acids form polypeptides abiotically when water with amino acids drys on hot clay.

9. THE ORIGIN OF LIFE Heterotrophic protocells probably came next. It is thought that these protocells had a cell membrane.

10. THE ORIGIN OF LIFE Protocells must have fed on the organic soup of the early oceans. Since there was no oxygen, we assume that the first cells were anaerobic fermenters.

11. THE ORIGIN OF LIFE Once the protocell was capable of reproduction, it became a true cell, and biological evolution began. Many scientists think that these ancient cells had RNA for their genetic code and later cells had DNA.

12. Classification: 3 Domains Bacteria Archaea Eukaryotes Anaerobic Heterotrophs capable of division Anaerobic Heterotrophic Protocells Organic Soup

13. Current Classification Schemes

14. HISTORY OF THE EVOLUTION CONCEPT The concept of evolution was formulated by Greek philosophers over 2000 years age. LeMarck (a French biologist; early 1800s) proposed a theory of evolution based on acquired characteristics. Charles Darwin (1860s) published his theory of evolution based on natural selection.

15. Mechanisms of Evolution Natural selection Mutation Isolation of Populations Mass Extinctions

16. Natural Selection Darwin and Wallace�s Theory Natural Selection means �Survival of the best adapted.� Nature is prolific. More individuals are produced than the environment can support -- thus competition. Individuals with mutations which are beneficial (cause better adaptation to the environment) have a better chance of surviving.

17. ISOLATION OF POPULATIONS Darwin�s observations occurred on the Galapagos Islands When a small population becomes geographically isolated from the main population, the small population tends to evolve into a separate species (speciation) because gene flow has been cut off from the main population.

18. Continental Drift

19. MASS EXTINCTIONS The fossil record shows that speciation (evolution) is most rapid following a mass extinction. Mammals and birds evolved rapidly into many different species after the dinosaurs were wiped out 65 million years ago. Humankind might not be here today had the dinosaurs not become extinct.

20. THE PACE OF EVOLUTION Darwin thought evolution proceeded gradually. Stephen Gould and some other modern paleontologists think that evolution tends to occur in spurts -- especially after a mass extinction. Gould believes that evolution is often rapid, then a new species remains constant for long periods until the next major environmental change spurs another burst of evolution.

21. THE PACE OF EVOLUTION Biologists know of some species that have changed very little over many millions of years because they are so well adapted to their niche or their way of life.

22. Evolutionary Evidences Artificial selection Fossil record Comparative anatomy Comparative embryology Comparison of DNA Vestigial structures

24. Artificial Selection All breeds of dog have evolved from a wolf ancestor through artificial selection by humankind over the last 10,000 years. Cabbage, broccoli, cauliflower, brussel sprouts all have been derived from a common ancestor by humankind in just a few thousand years.

25. FOSSIL RECORD Fossils of the simplest organisms are the oldest. Fossil evidence for the evolution of vertebrates is more complete than for soft-bodied animals. Fossil evidence for transitional forms like Archaeopteryx is strong. Fossil evidence for human evolution is compelling.

26. Comparative Anatomy The bone types in the limbs of amphibians, reptiles, birds, and mammals is very similar. This suggests common ancestry.

27. COMPARATIVE EMBRYOLOGY All vertebrate animals are similar in their early embryonic development. They all have a notochord, tail, and gill pouches in their early development. In humans, the notochord is replaced by backbone, the tail degenerates, and gill pouches become the Eustachian tube, tonsils, and glands in the neck region.

28. COMPARISON OF DNA Chimpanzees and humans have a DNA similarity of 99%. Humans and cows would have less DNA similarity. Humans and jellyfish would have still fewer genes in common. The degree of DNA similarity between two organisms indicates how closely related they are.

29. VESTIGAL STRUCTURES The appendix, coccyx, and embryonic tail are vestigal structures in humans. Nonfunctional eyes in cave fish are vestigal. Vestigial pelvic bones are present in the body of the python.

30. VERTEBRATE EVOLUTION The ancestor of the vertebrates was a small fishlike animal with a notochord that lived in the seas about 500 million years ago. The first fishes were jawless. Today the only surviving jawless fishes are lamprey.

31. VERTEBRATE EVOLUTION Some of the jawless fishes evolved into jawed fishes . The early jawed fishes evolved into: cartilaginous fishes bony fishes

32. VERTEBRATE EVOLUTION Today there are many bony fishes. Cartilaginous fishes include sharks, skates, and rays. Some of the early lobe-finned fishes evolved into the first amphibians.

33. VERTEBRATE EVOLUTION Amphibians today include frogs, toads, and salamanders. Some of the early amphibians evolved into the first reptiles. Today reptiles include: snakes, lizards, turtles, crocodiles, and alligators.

34. VERTEBRATE EVOLUTION The reptiles are better adapted to dry land living because of their waste-proof eggs and scaly skin. Some of the early reptiles evolved into the first birds and mammals.

35. VERTEBRATE EVOLUTION Archaeopteryx was the first bird according to the fossil record. It had these reptilian features: teeth in beak claws long reptilian tail vertebrae

36. VERTEBRATE EVOLUTION Archaeopteryx was a bird because it had feathers. Early mammals were shrew-like animals. When dinosaurs became extinct, birds and mammals expanded into many diverse species.

37. HOMINID EVOLUTION Hominids are primates which walk upright. The first hominid we have fossils of is �Lucy� Australopithecus afarensis from Africa.

38. Hominid Evolution Homo habilis used stone tools. Homo erecutus used fire. Homo sapiens neanderthalensis lived during the Ice Age. They were hardy, muscular hunters who buried their dead.

39. Major episodes

40. Earth�s Inhabitants