Evolution

1. Evolution Ms. Luaces

2. Quick Review: Theory vs. Law • Theory: A well-tested explanation to make accurate predictions • They can be changed! • Law: A generalized way of explaining things, but doesn’t necessarily say why • Law of gravity • Can’t be disproven

3. Earth’s Early History – 19.3 • What do scientists hypothesize about early Earth and the origin of life? • What theory explains the origin of eukaryotic cells? • What is the evolutionary significance of sexual reproduction?

4. The Mysteries of Life’s Origins • Earth was struck by a large object and heated • Eventually cooled down enough to form oceans • It’s atmosphere had very little oxygen

5. The Mysteries of Life’s Origins • Miller and Urey’s experiment suggested how mixtures of organic compounds necessary for life could have arisen • Not entirely accurate… more recent experiments have been done • First formations were thought to be proteinoid microspheres that had some characteristics of living things – NOT CELLS!

6. The Mysteries of Life’s Origins • “RNA World” hypothesis states that RNA came before DNA… do you think this is possible?

7. The Mysteries of Life’s Origins • First forms of live evolved to live in an oxygen free world – anaerobic prokaryotes • Eventually, photosynthetic bacteria came around which produced _________. This allowed aerobic organisms to evolve.

8. Origin of Eukaryotic Cells Eukaryotic Prokaryotic Have nucleus Have membrane-bound organelles Have mitochondria No nucleus Very few membrane-bound organelles

9. Origin of Eukaryotic Cells • The endosymbiosis theory suggests that a __________ relationship evolved between eukaryotes and prokaryotes • Created the mitochondria and the chloroplasts we know today

10. Origin of Eukaryotic Cells • In support of this hypothesis: • Mitochondria and chloroplasts contain their own DNA which is similar to bacteria DNA. • Have their own ribosomes • Replicate like bacteria (binary fission)

11. Sexual Reproduction • Important in our evolutionary history because it introduces genetic diversity / variation. • Genetic variation increases the likelihood of a population adapting to new or changing environmental conditions.

12. Evidence of Evolution – 16.4 • How does the geographic distribution of species today relate to their evolutionary history? • How do fossils help to document the descent of modern species from ancient ancestors? • What do homologous structures and similarities in embryonic development suggest about the process of evolutionary change? • How can molecular biology be used to trace the process of evolution? • What does recent research on the Galapagos finches show about natural selection?

13. Evidence of Evolution • Darwin hypothesized that animals evolved because of natural selection… what is that??

14. Biogeography • Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors.

15. Biogeography Closely related but different Distantly related but similar Alike species with different traits Different species with same traits (similar environment)

16. Age of Earth & Fossils • Radioactive data shows Earth to be 4.5 billion years old – supporting Darwin’s theory (lots of time for evolution) • Recent fossil records are filling the gaps, showing that modern species evolved from extinct ancestors.

17. Comparing Anatomy & Embryology • Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.

18. Comparing Anatomy & Physiology Homologous Analogous Similar structure Similar function

19. Comparing Anatomy & Embryology • Vestigial structures aren’t necessary, but don’t harm the function of the organism and so they remain • Appendix!

20. Comparing Anatomy & Embryology • Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.

21. Genetics & Molecular Biology • At the molecular level, the universal genetic code and homologous molecules provide evidence of common descent • Most of the DNA and RNA used from bacteria to humans is the same. We must have come from a common ancestor!

22. Genetics & Molecular Biology • Homologous proteins are shared from bacteria to humans – how we make insulin from bacteria for our use. • Homologous genes exist between flies and humans – these same genes direct our head-to-tail development and limbs

23. Testing Natural Selection • The Grant’s were able to test Darwin’s hypothesis by: • Analyze that there was enough heritable variation in the traits for natural selection • There were enough differences in beak size and shape to produce differences in fitness

24. Testing Natural Selection • Dry weather = more survival of large beak birds • Their data confirmed that competition and environment drive natural selection

25. Hominine Evolution – 26.3 (Pg. 767) • What adaptations enabled later hominine species to walk upright? • What is the current scientific thinking about the genus Homo?

26. Hominine Evolution • We separated to create hominines and chimpanzees • The skull, neck, spinal column, hip bones, and leg bones of early hominine species changed shape in ways that enabled later species to walk upright – bipedal.

27. Hominine Evolution • Bipedal allowed us to free our hands for tools – developed opposable thumbs • Also developed larger brains (cerebrums) • Figure 26-16 gives major differences between humans and gorrillas

28. Hominine Evolution • Fossils date back to 7 million years old – not all findings are ancestors, they may be relatives • Research suggests bipedalism evolved before larger brains • Oldest hominine: 2002, Sahelanthropus • Best studied:1974, Australopithecus afarensis or Lucy

29. Hominine Evolution • Recent research shows our human evolution isn’t straight forward – more like several branches and several trunks • Homo habilis: “handy man”, probably our ancestor • Homo ergaster: bigger brain, downward-facing nostrils

30. Hominine Evolution • Our genus originated in Africa and migrated from there to populate the world • Homo habilisin Turkey • Homo Erectus in Asia

31. Hominine Evolution • Multiregional hypothesis says we evolved independently in various parts of the world • “Out-of-Africa” model suggests we migrated and colonized the rest of the world about 200,000 years ago • More supported theory by mitochondrial DNA evidence

32. Hominine Evolution • Modern humans may or may not have coexisted with Neanderthals… something made Neanderthals go extinct and Homo sapiens remain the only hominine clade. • Both used stone tools, lived in complex social groups, controlled fire, and had rituals to bury their dead.

33. GO HEAT!!

34. The Brain (Pg. 902-903) • Split into 5 major components: • Cerebrum • Limbic System • Thalamus and Hypothalamus • Cerebellum • Brain Stem

37. The Brain • Cerebrum: largest region of the brain responsible for voluntary (conscious) activities • Intelligence, learning and judgment are stored here • The part that grew the most in our ancestors

38. The Brain • The Cerebrum is split up into right and left hemispheres • Left hemisphere controls right-side of the body and vice versa • Also into four lobes • Frontal (planning, judgments) • Temporal (hearing and smell) • Parietal (reading and speech) • Occipital (vision)

39. The Brain • The Cerebrum also has two layers • The cerebral cortex (topmost layer, aka grey matter) which has many of the neurons responsible for all the activities • White matter (innermost layer) which makes connections between different brain areas

40. The Brain • Limbic System: mostly associated with emotions, behavior, and long-term memory

42. The Brain • Thalamus: receives messages from sensory neurons and sends them to the right place • Hypothalamus: helps to know and analyze hunger, thirst, fatigue, anger, and body temperature

44. The Brain • Cerebellum: second largest region of the brain which deals with coordinating the body’s actions

45. The Brain • Brain stem: the oldest part of the brain which connects the brain to the rest of the body • Also controls important functions like blood pressure, heart rate, breathing, and swallowing • What keeps you breathing while you sleep

46. Let’s Practice • From Activity workbook B: I will assign you a study buddy to work with and complete the following: • 31.2, pages 480-481 • 1 separate sheet of paper for each group of 2 for Workbook B: Questions and answers (including the brain diagram). • Pages 86-89 #4 from your EOC Coach workbook. • Each one is to complete #4 in their EOC coach workbook • Due today

47. Darwin’s Voyage of Discovery – 16.1 • Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors • Darwin was born in 1809 and began his journey in 1831 on the HMS Beagle

48. Observations Aboard The Beagle • Darwin didn’t just observe species, he thought about them in scientific ways and noticed • Species vary globally • Species vary locally • Species vary over time • Different species inhabit separate, but ecologically similar habitats

49. Observations Aboard The Beagle • Darwin also noticed that different, yet related animal species occupied different habitats within a local area • All his observations were conducted between Australia, South America, and Africa (and of course, the Galapagos)

50. Observations Aboard The Beagle • Darwin also noticed that some fossils of extinct animals were similar to living species – the Glyptodont and the Armadillo • All of this evidence suggested that species are not fixed, but that they change by some kind of natural process which we know today as ________________.