1. EVOLUTION Chapter 13

2. Darwin’s Theory of Evolution Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. Evolution A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world. A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.theory

3. Voyage of the Beagle

4. Voyage of Beagle Dates: February 12th, 1831 Dates: February 12th, 1831 Ship: H.M.S. Beagle Ship: H.M.S. Beagle Destination: Voyage around the world. Destination: Voyage around the world. Findings: evidence to propose a revolutionary hypothesis about how life changes over time as a result of an organisms environmental conditions. Findings: evidence to propose a revolutionary hypothesis about how life changes over time as a result of an organisms environmental conditions.

6. Science Before Darwin’s Voyage Most people believed each species was a divine creation. Scientists were trying to explain the origin of fossils.  Some tried to explain it by altering traditional explanations.  Others (including Darwin’s grandfather) proposed mechanisms to explain how living things change over time. 1809: French scientist Jean Baptiste Lamarck proposed a hypothesis for how organisms change over generations.  He believed that over the lifetime of an individual, physical features increased in size b/c of use or reduce in size b/c of disuse.  He also believed these changes were then passed on to offspring. .

7. Science Before Darwin’s Voyage This is now known to be incorrect, however he did correctly point out that the changes that occur in species are due to the physical conditions of life- this refers to an organisms environmental conditions. This is now known to be incorrect, however he did correctly point out that the changes that occur in species are due to the physical conditions of life- this refers to an organisms environmental conditions.

8. Darwin’s Observations During Darwin’s voyage on the Beagle, he found evidence that species were not unchanging. During Darwin’s voyage on the Beagle, he found evidence that species were not unchanging. Darwin was reading a book that discussed how changes in the Earth could occur over many years. Darwin was reading a book that discussed how changes in the Earth could occur over many years. While he was out, he started to notice evidence of this. While he was out, he started to notice evidence of this.  Fossils- he found fossils in South America of extinct armadillos. These armadillos closely resembled, but were not identical to the armadillos still living in the area.

9. Fossils

10. The Galapagos Islands Located 620 miles off the coast of Ecuador. Located 620 miles off the coast of Ecuador. He noticed that many plants/animals resembled those of the nearby coast of South America. He noticed that many plants/animals resembled those of the nearby coast of South America. Darwin hypothesized that the most simple reason for this was that these animals had migrated to the islands and then changed over time. Darwin hypothesized that the most simple reason for this was that these animals had migrated to the islands and then changed over time. Eventually Darwin called this “descent with modification” – what we now refer to as evolution. Eventually Darwin called this “descent with modification” – what we now refer to as evolution.

13. Animals found in the Galapagos Land Tortoises Land Tortoises Darwin Finches Darwin Finches Blue-Footed Booby Blue-Footed Booby Marine Iguanas Marine Iguanas

15. Animals

16. The Journey Home When Darwin was 27, he returned home, but did not report his findings. When Darwin was 27, he returned home, but did not report his findings. He continued to study his data, until his confidence grew that he was correct in his conclusions. He continued to study his data, until his confidence grew that he was correct in his conclusions. His hypothesis: Separate species may have arose from an original ancestor His hypothesis: Separate species may have arose from an original ancestor

17. Population Growth Thomas Malthus-19th century English economist Thomas Malthus-19th century English economist If population grew (more babies born than die) If population grew (more babies born than die)  Insufficient living space  Food runs out (populations are able to increase faster than food supply increases).  He proposed that human populations do not grow unchecked because of death caused by disease, war, and famine that slows population growth.  Darwin applied this theory to animals.

18. Growth of Populations Population: includes all of the individuals of a species that live in a specific geographical area AND can interbreed (breed with one another). Population: includes all of the individuals of a species that live in a specific geographical area AND can interbreed (breed with one another). Evolution by Natural Selection Evolution by Natural Selection Darwin realized that Mathus’ conclusions about human population growth applied to all species. Darwin realized that Mathus’ conclusions about human population growth applied to all species.  Every organism has the potential to produce many offspring during its life time.  But, not all of them will survive.

19. Natural Selection After gathering all of his information, Darwin made a conclusion: “individuals that have physical or behavioral traits that better suit their environment are more likely to survive and will reproduce more successfully than those that do not have such traits”. Darwin called this natural selection. After gathering all of his information, Darwin made a conclusion: “individuals that have physical or behavioral traits that better suit their environment are more likely to survive and will reproduce more successfully than those that do not have such traits”. Darwin called this natural selection.  Over time, the number of individuals that carry favorable characteristics that are ALSO inherited will increase in a population. Therefore, the population will change. This changes = evolution.

20. Publication of Origin of Species 1844 Darwin wrote down his ideas about evolution & natural selection, but didn’t publish his data due to the controversy that other scientist were facing concerning this topic- he wasn’t confident enough. 1844 Darwin wrote down his ideas about evolution & natural selection, but didn’t publish his data due to the controversy that other scientist were facing concerning this topic- he wasn’t confident enough. Finally, he wrote the book & it was published in Nov 1859. Finally, he wrote the book & it was published in Nov 1859.

21. Darwin’s theory of evolution by natural selection is supported by 4 major points. 1)Inherited variation exist w/in the genes of every population or species (the result of random mutation & translation errors). 2)In a particular environment, some individuals of a population or species are better suited to survive (as a result of variation) and have more offspring (natural selection). 3)Over time, the traits that make certain individuals of a population able to survive and reproduce tend to spread in that population. 4)There is overwhelming evidence from fossils & many other sources that living species evolved from organisms that are extinct.

22. Darwin’s Ideas Updated Change within populations: Change within populations:  Darwin’s main point was that in any population, the individuals that are best suited to survive & do well in their environment will produce the most offspring. So, the traits of those individuals will become more common in each new generation.  Now, we know that genes are responsible for inherited traits.  Natural selection causes the frequency of certain alleles in a population to increase or decrease over time.  Mutations & the recombination of alleles that occurs during sexual reproduction provide for endless sources of new variation.

23. Darwin’s Ideas Updated

24. Species Formation Because the environment differs from place to place, populations of the same species living in different locations tend to evolve in different directions. Because the environment differs from place to place, populations of the same species living in different locations tend to evolve in different directions. Reproductive Isolation is the condition in which two populations of the same species do not breed with one another b/c of geographic separation, a difference in mating periods, or other barriers to reproduction. Reproductive Isolation is the condition in which two populations of the same species do not breed with one another b/c of geographic separation, a difference in mating periods, or other barriers to reproduction.

25. Reproduction Isolation  Two populations of the same species do not breed with one another because of geographic separation, a difference in mating periods, or other barrier to reproduction  These isolated populations will become more different over time until they are no longer able to breed with one another

26. The Tempo of Evolution Evolution is understood to be a gradual process that occurs continuously. Evolution is understood to be a gradual process that occurs continuously. This is called gradualism. This is called gradualism. Some scientists believe that evolution of some species may actually occur in short spurts, followed by long periods of no change. This change is called punctuated equilibrium. Some scientists believe that evolution of some species may actually occur in short spurts, followed by long periods of no change. This change is called punctuated equilibrium.

27. The Tempo of Evolution

28. Natural Selection Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment

29. Natural Selection Descent with modification = Natural Selection

30. Evidence of Evolution The Fossil Record The Fossil Record Geographic Distribution of Living Things Geographic Distribution of Living Things Homologous Body Structures Homologous Body Structures Vestigial Organs or Structures Vestigial Organs or Structures Similarities in Early Development Similarities in Early Development Changes in DNA Changes in DNA

31. Evidence of Evolution The Fossil Record Geographic Distribution of Living Things-similar environments have similar types of organisms Homologous Body Structures Similarities in Early Development

32. Section 2: Evidence of Evolution Fossils: offer the most direct evidence that evolution takes place. Fossils: offer the most direct evidence that evolution takes place.  A preserved/mineralized remain or imprint of an organism that lived long ago.  Provide an actual record of Earth’s past life-forms.  Change over time can be seen in the fossil record. ie. Fossilized species found in older rocks are different from those found in newer rocks.ie. Fossilized species found in older rocks are different from those found in newer rocks.

33. After observing the differences in fossils, Darwin predicted that intermediate forms between groups of organisms would eventually be found. After observing the differences in fossils, Darwin predicted that intermediate forms between groups of organisms would eventually be found.  Some have been found.  Some have not. These intermediate forms are called transitional fossils. These intermediate forms are called transitional fossils.  Any fossil which gives us information about a transition from one species to another.

34. Examples of transitional fossils

35. Darwin’s theory is almost universally accepted by scientists as the best available explanation for the biological diversity on Earth: Darwin’s theory is almost universally accepted by scientists as the best available explanation for the biological diversity on Earth:  Based on supporting evidence, most scientists agree on these 3 points:  The Earth is about 4.5 million years old.  Organisms have inhabited the Earth for most of its history.  All organisms living today share common ancestry with earlier, simpler life forms.

36. Studying fossils Paleontologist: scientists who study fossils. Paleontologist: scientists who study fossils.  They analyze the sediments around the fossils.  They use radiometric dating of certain rocks and minerals to arrange fossils in order from oldest to youngest.  This creates a visual pattern of evolution.

38. Anatomy & Development Studying the anatomy of different types of organisms often reveals basic similarities in body structures even through the structures function may differ between organisms. Studying the anatomy of different types of organisms often reveals basic similarities in body structures even through the structures function may differ between organisms.  Vestigial structures  Homologous structures  Embryonic development

39. Homologous Structures -structures that have different mature forms in different organisms, but develop from the same embryonic tissue. Homologous Structures -structures that have different mature forms in different organisms, but develop from the same embryonic tissue.

41. Vestigial organs-organs that serve no useful function in an organism Vestigial organs-organs that serve no useful function in an organism Vestigial organs-organs that serve no useful function in an organism Vestigial organs-organs that serve no useful function in an organism i.e.appendix, miniature legs, arms i.e.appendix, miniature legs, arms i.e.appendix, miniature legs, arms i.e.appendix, miniature legs, arms

42. Similarities in Early Development

43. CHANGES IN DNA Natural Selection at Work Natural Selection at Work  Mutation – a change in the nucleotide- base sequence of a gene or DNA molecule  If species have changed over time, then the genes that determine the species’ characteristics should also have changed by mutation

44. Section 3- Examples of Evolution Natural Selection at Work Natural Selection at Work  In Darwin’s writings, he offered examples of how natural selection could have shaped life on Earth.  KEY POINT: The environment dictates the direction and amount of change.  If the environment changes in the future, the set of characteristics that most help an individual reproduce successfully may also change.

45. Factors in Natural Selection The process is driven by 4 important points that are true for all real populations. The process is driven by 4 important points that are true for all real populations.  All populations have genetic variation  The environment presents challenges to successful reproduction.  Individuals tend to produce more offspring than the environment can support.  Individuals that are better able to cope with the challenges tend to leave more offspring than those who aren’t.

46. An example Evolution of antibiotic resistant diseases. Evolution of antibiotic resistant diseases.  The bacteria needs to survive to reproduce.  Eventually, a mutation will occur in its genome that will allow even one bacteria cell to fight off the antibiotics. As it reproduces, more antibiotic resistant cells are made and the antibiotic currently used becomes ineffective. Darwin’s Finches: different beaks utilized during food shortage. Darwin’s Finches: different beaks utilized during food shortage.

47. An example

49. Formation of a new species Species formation occurs in stages. Species formation occurs in stages. Natural selection favors changes that increase reproductive success. Natural selection favors changes that increase reproductive success. So, species are improved to “fit” into their environment (ie. Fitness). So, species are improved to “fit” into their environment (ie. Fitness). Accumulation of differences between groups- divergence. Accumulation of differences between groups- divergence. Divergence leads to the formation of new species. Divergence leads to the formation of new species. Formation of new species- speciation. Formation of new species- speciation.

50. Forming subspecies In environments differ enough, then separate populations of the same species can become so different that they become a new species. In environments differ enough, then separate populations of the same species can become so different that they become a new species. Populations of the same species that differ genetically b/c of adaptations to different living conditions become subspecies. Populations of the same species that differ genetically b/c of adaptations to different living conditions become subspecies. Once they are different enough, the subspecies may become a completely separate species. Once they are different enough, the subspecies may become a completely separate species.  Due to reproductive barriers that form.

51. Summary of Darwin’s Theory Individuals in nature differ from one another Individuals in nature differ from one another Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce. Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce.

52. Summary of Darwin’s Theory Because more organisms are produce than can survive, each species must struggle for resources Because more organisms are produce than can survive, each species must struggle for resources Each organism is unique, each has advantages and disadvantages in the struggle for existence Each organism is unique, each has advantages and disadvantages in the struggle for existence

53. Summary (cont.) Individuals best suited for the environment survive and reproduce most successful Individuals best suited for the environment survive and reproduce most successful Species change over time Species change over time

54. Summary (cont.) Species alive today descended with modification from species that lived in the past Species alive today descended with modification from species that lived in the past All organisms on earth are united into a single family tree of life by common descent All organisms on earth are united into a single family tree of life by common descent