Evolution by Means of Natural Selection (Ch.10)

1. Evolution by Means of Natural Selection (Ch.10)

2. Early scientists proposed ideas about evolution. • Evolution is the biological change process by which descendants come to differ from their ancestors. • A species is a group of organisms that can reproduce and have fertile offspring. (Linnaeus)

3. Historical thought • Greek- Aristotle (3rd c. BC)- Scala Naturae- “great chain of being” or the “ladder of life” • Connects all living things moving toward a goal • Literal Biblical view- the world was created in 6 days • Earth is 6000 years old • all species were created as they are today

4. de Buffon • Everything is related; share a common ancestor instead of arising separately • Goes against any Christian beliefs.

5. Influence of Geology • James Hutton- gradualism • Things that change the earth take A LONG TIME • Charles Lyell- current earth-shaping processes are the same as the past • stressed that scientists must explain past events in terms of processes that they can actually observe, • Wrote Principles of Geology, read by Darwin

6. William Smith • Each layer (stratum) of rock had unique fossil records • The older the strata, the more dissimilar the organisms are to present forms • George Cuvier • Documented extinction as a common occurrence

7. Population size link to poverty and disease If human population continued to grow unchecked (grows expontentially), it will be limited by space and food supply (grows arithmetically) Population outgrows resources and competition kicks in That applies to more than just us! Turtles lay hundreds of eggs, few survive Trees set out hundreds of seeds, how many actually mature? There is some selecting factor that decides which organisms are most fit for survival… Thomas Malthus

8. Lamarck’s Hypothesis • Tendency Toward Perfection • they are continually changing and acquiring features that help them live more successfully in their environments • Use and Disuse • organisms could alter the size or shape of particular organs by using their bodies in new ways • Inheritance of acquired characteristics • if during its lifetime an animal somehow altered a body structure, it would pass that change on to its offspring

9. Why/How did giraffes develop long necks?

10. Lamarck’s Giraffes

11. Lamarck’s hypothesis of evolution was the first to recognize that organisms are well suited for their environment – this is a key concept for future work. Lamarck’s Hypothesis (1809)

12. Charles Darwin • more-complex forms developed from less-complex forms • Species on the Galapagos Islands were similar to the mainland, but differ in each environment • Variation naturally exists within a natural or domesticated population and some of that variation is inheritable

13. Galapagos Finches

14. Alfred Wallace • Co-discovery of natural selection • Published with Darwin • Lesser known because he was poor.

15. So… • Why is Lamarck wrong? • How did his hypothesis positively influence evolutionary thought?

16. Paleontology • Def: the study of collecting and studying fossils • William Smith • Each layer (stratum) of rock had unique fossil records • The older the strata, the more dissimilar the organisms are to present forms

17. Fossils provide a record of evolution. • Paleontology is the study of fossils or extinct organisms.

19. Theories of geologic change set the stage for Darwin’s theory. • There were three theories of geologic change. • Catastrophism Catastrophes cause extinction and promote new species • Gradualism slow changes helped to promote new species who are better adapted to the environment • Uniformitarianism the process that are shaping the earth today have been going on forever

21. Darwin observed differences among island species. • Variation is a difference in a physical trait. • Galápagos tortoises that live in areas with tall plants have long necks and legs. • Galápagos finches that live in areas with hard-shelled nuts have strong beaks.

22. Natural Variation in Species Darwin Believed that natural variation already existed in a species and the environment chose the best suited variation Darwin did not show a mechanism for how traits were inherited

23. Galapagos Tortoises • Morphology matched function in the environment.

24. An adaptations is a feature that allow an organism to better survive in its environment. • Species are able to adapt to their environment. • Adaptations can lead to genetic change in a population.

25. Definitions and Concepts: • Adaptation – any inherited characteristic that increases an organism’s chance of survival and ability to reproduce. • Ex. Monarch butterfly is poisonous to eatthey have special coloration to warn predatorsalso viceroy butterflies copy their coloration to protect themselves • Fitness – the ability of an organism to survive and reproduce.

26. SECTION 3

27. Theory of Biological Evolution by means of Natural Selection • Struggle for Existence • Survival of the “fittest”, or Natural Selection • Fitness- ability to survive and reproduce • Adaptations- can be morphological, behavioral, or physiological • An adaptation may be an advantage in one environment and a disadvantage in another! • Natural Selection • Only acts on heritable traits • Does not form NEW characteristics (only mutations can do that!) • Is backward looking, not planned • acts on the individual, but the effect is on the POPULATION

28. Artificial Selection • Man chooses which traits are more appealing to him, then breeds the organism to produce those traits

29. Theory of Biological Evolution by means of Natural Selection • Species alive today are descended with modification from ancestral species that lived in the distant past. • This process by which diverse species evolved from a common ancestor unites ALL organisms on Earth into a singletree of life.

30. The story of the Peppered Moth • How did the industrial revolution change a species of moth? • Peppered Moth Animation

31. Peppered Moth Simulation Discussion questions: 1. What differences were present in the moths? What caused those differences? Where they differences in morphology or physiology? 2. Before the industrial revolution, which color of organism had the adaptation that was most fit for the environment? 3. What type of selective pressures acted on the moths?

32. Definitions and Concepts: • Selective Pressure – any phenomenon which alters the fitness of organisms within a given environment. It is the driving force of natural selection, and it can be divided into two types of pressure: biotic or abiotic. • Ex: predation, food supply, temperature.

33. Some antelopes are swift and instinctively run in a zig-zag pattern. Some lions are fast and powerful.   What is the source of variation in antelopes? What is the selective pressure? What is the adaptation that made it successful in the environment? Example of selective pressure:

34. The wide use of antibiotics has caused many bacteria like Mycobacterium tuberculosis to evolve a resistance to antibiotics. Some of the bacteria in this population contained mutant genes that defended the bacteria from the antibiotic drug. These few bacteria did not die when they were exposed to the antibiotic. These resistant bacteria reproduced more bacteria like themselves that were resistant to the antibiotics. This resistance is evidence of change or evolution of a species. Read the following information and answer the questions on the next slide.

35. Activity – Bacteria Resistance

36. 1. What was the ultimate source of variation in the species? 2. What was the selective pressure described? 3. What was the adaptation of the organism that made it successful in the changed environment? 4. How did the Mycobacterium tuberculosis change? Activity – Bacteria Resistance

37. Thirteen species of finches live on the Galápagos, the famous island group visited by Charles Darwin in the 1830s. The finches have a variety of bill shapes and sizes, all suited to their varying diets and lifestyles. Some birds have beaks better suited for eating cactus; some have long beaks better suited for eating insects, or short beaks for eating hard seeds. A variety of finches ended up on moist, rainy islands in which there was a shortage of seeds, but many grub-like insects were living under tree bark. The long-beaked birds could survive on grubs, and would pass their genetic traits to their offspring. The others would die out. Natural selection caused the long beaked ‘woodpecker finch’ to survive. Darwin did not believe that the environment was producing the variation within the finch populations.  He correctly thought that the variation already existed and that nature just selected for the most suitable beak shape and against less useful ones. Activity – Galapagos Finches

39. 1. What was the ultimate source of variation in the species? 2. What was the selective pressure described? 3. What was the adaptation of the organism that made it successful in the changed environment? 4. How did the finch change? Activity – Galapagos Finches

40. Deer Mice Deer mice are widespread across North America, but they usually have dark coat, so that they can blend into dark soils and stay hidden from owls. However, soil in Nebraska is light-colored sand. Over a period of several thousand years the deer mouse in Nebraska evolved a pale coat that helped it to evade predators. Scientists at Harvard and at the University Of California at Berkeley discovered a single gene called Agouti in light colored mice which is expressed in higher amounts and for longer than the genes that code for dark hair. The gene emerged about 4,000 years ago, which was only a few thousand years after the dark coated mice colonized the new sandy home. Its spread was rapid. Agouti did not occur before the colonization of the sandy environment, and when it did appear selection acted on it to confer an advantage, making it more widespread

42. Activity – Deer Mice 1. What was the ultimate source of variation in the deer mice? 2. What was the selective pressure described? 3. What was the adaptation of the organism that made it successful in the changed environment? 4. How did the population of deer mice change?

43. The term “survival of the fittest” is closely associated with Charles Darwin’s ideas of change over time. If an organism is “fit”, it most likely will – A. become extinctB. pass down its genes to an offspringC. migrate to a new ecosystemD. change in order to survive

44. 2. Lizards closely resemble the plants and trees in which they live. This is most likely because A. the lizard has learned to change colors.B. the lizard is smaller than the leaves of the trees.C. ancestors of the lizards with the same traits survived and reproduced.D. the food eaten by lizards lives in plants.

45. To break it down… • Organisms produce offspring and those that do not survive do not reproduce therefore they do not pass down their genes • Each organism has different advantages and disadvantages in the struggle for existence. • Individuals best suited the their environment survive and reproduce most successfully

46. Section 4

47. Evidence of Evolution includes The fossil record Geographic distribution of living species Homologous body structures Similaritiesin early development which is composed of which indicates which implies which implies Physical remains of organisms Common ancestral species Similar genes Similar genes Evidence of Evolution

48. Figure 15–14 Geographic Distribution of Living Species • Can indicate common ancestry from fossil forms that occupied a continuous area.

49. Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara NORTH AMERICA Muskrat Capybara SOUTH AMERICA Figure 15–14 Geographic Distribution of Living Species • Can indicate similar structures forming due to similar habitats (and therefore similar selective pressures)

50. Discuss with your neighbor…What conclusion can you draw from the information below? • Rhea – Native to South America • Ostrich – Native to Africa • Emu – Native to Australia