Evidence of Evolution

1. Evidence of Evolution • The Fossil Record- ch 14 • Geographic Distribution of Living Things-similar environments have similar types of organisms • Body Structures • Homologous, • analogous, • vestigial • Similarities in Early Development

2. Evidence of EvolutionHomologous Structures

3. Analogous Structures • Body part in different species that is similar in function but not in structure • that evolved in response to a similar environmental challenge

4. Evidence for Evolution • Vestigial organs-organs that serve no useful function in an organism • i.e.) appendix, miniature legs, arms

5. Evidence of EvolutionSimilarities in Early Development • Same • DNA & processes • Comparative embryology

6. Lamarackacquired traits can be inherited 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 ONLY OCCURS IF IT IS CAUSED BY A MUTATION

7. In 1809, Jean Baptiste de Lamarck suggested that characteristics, or traits, developed during a parent organism’s lifetime are inherited by its offspring. His hypothesis is called the inheritance of acquired characteristics. Scientists collected data on traits that are passed from parents to offspring. The data showed that traits developed during a parent’s lifetime, such as large muscles built by hard work or exercise, are not passed on to offspring. The evidence did not support Lamarck’s hypothesis. Hypothesis of Acquired Characteristics Mutations are the only way new traits can appear?

8. Ideas About Evolution 1 Darwin’s Model of Evolution • In December 1831, Charles Darwin recorded observations about the plants and animals he saw on the South American coast.

9. Adaptive Radiationthe diversification of an ancestral group of organisms into a varietyofrelated forms specialized to fit different environments or ways of life • Darwin hypothesised evolution, that the different species of Galapagos finches descended from mainland finches that had reached the islands sometime in the past. Over time they evolved and gradual changes occurred to the island finches. Eventually they were different enough from the mainland finches to be considered a new species. Darwin proposed the island had become inhabited by many different but related species of finches. -

10. Main Idea • Charles Darwin- natural selection describes the unequal survival & reproduction that results from the presence or absence of particular traits • It is responsible for evolution • Selecting and breeding for specific traits is evolution by artificial selection • We have unintentionally selected for pests that are resistant to pesticides and for bacteria that are resistant to antibiotics

11. Charles Darwin collected more evidence on inherited traits by breeding racing pigeons. He also studied breeds of dogs and varieties of flowers. In the mid 1800s, Darwin developed a theory of evolution that is accepted by most scientists today. Natural Selection

12. Evolution by Natural Evolution

13. Darwin’s Theory of Evolution • 1. Overpopulation- more offspring than can survive • 2. Variation- individuals vary. • 3. survival of the fittest- best adapted to survive. & natural selection- survivors pass on traits • 4. When reproductive isolation occurs new species will form

14. Darwin’s TheoryWhat state do these represent?

15. Nature Selects • Adaptation is the process of becoming adapted to an environment. It is an anatomical, physiological, or behavioral change that improves a population’s ability to survive.

16. Elephant Bird

17. http://www.pbs.org/wgbh/evolution/

18. A population is all of the individuals of a species living in the same area. Members of a large population compete for living space, food, and other resources. Only those that survive (best adapted) can reproduce and pass on their traits to the next generation. If you do not have traits that help you survive you go extinct and the traits are not passed on to the offspring Darwin’s TheorySurvival of Fittest

19. Darwin’s ideas became known as the theory of evolution by natural selection. Natural selection means that organisms with traits best suited to their environment are more likely to survive and reproduce. Darwin’s Theory

20. Mimicry-copies appearance of another org Camouflage- blends w/surroundings Whether a variation is helpful or harmful depends on the env Flounders Sphinx Moth

21. Natural Selection • Process in which something in a living thing’s surroundings determines if it will or will not survive to have offspring. • Organisms suited to their env. Survive • Only the ones who survive can have offspring and pass on traits

22. Summary of Darwin’s Theory • 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.

23. Summary of Darwin’s Theory • 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

25. Evolution Summary • Species alive today descended with modification from species that lived in the past

27. All organisms on earth are united into a single family tree of life by common descent

28. Five Mechanisms of Microevolution 1. Genetic drift: Change in the gene pool of a small population due to chance. • Two examples: a. Bottleneck effect b. Founder effect

29. a. Bottleneck Effect • Genetic drift (reduction of alleles in a population) resulting from a disaster that drastically reduces population size. • Examples: 1. Earthquakes 2. Volcano’s

31. b. Founder Effect • Genetic drift resulting from the colonization of a new location by a small number of individuals. • Results in random change of the gene pool. • Example: 1. Islands (first Darwin finch)

34. Many scientists hypothesize that evolution occurs slowly, perhaps over tens or hundreds of millions of years. Other scientists hypothesize that evolution can occur quickly. Most scientists agree that evidence supports both of these models. Tuatara is undergoing mutations faster than any other known species The Speed of Evolution

35. Interpretations of Speciation • Two theories: 1. Gradualist Model (Neo-Darwinian): Slow changes in species overtime. 2. Punctuated Equilibrium: Evolution occurs in spurts of relatively rapid change.

36. Many scientists hypothesize that evolution occurs slowly, perhaps over tens or hundreds of millions of years. Other scientists hypothesize that evolution can occur quickly. Most scientists agree that evidence supports both of these models. Tuatara is undergoing mutations faster than any other known species The Speed of Evolution

37. The model that describes evolution as a slow, ongoing process by which one species changes to a new species According to the gradualism model, a continuing series of mutations and variations over time will result in a new species. A series of intermediate forms can indicate a gradual change from the earliest species to today’s species. Gradualism

38. The model that describes evolution as a slow, ongoing process by which one species changes to a new species According to the gradualism model, a continuing series of mutations and variations over time will result in a new species. A series of intermediate forms can indicate a gradual change from the earliest species to today’s species. Gradualism

39. Darwins Theory Summary • The most successful Individuals best suited for the environment survive and reproduce • Species change over time

42. Evolution by the punctuated equilibrium model can occur over a few thousand or million years, and sometimes even faster. For example, many bacteria have changed in a few decades. The antibiotic penicillin originally came from the fungus Penicillium. But many bacteria species that were once easily killed by penicillin no longer are harmed by it. Penicillin has been in use since 1943. Just four years later, in 1947, a species of bacteria that causes pneumonia and other infections already had developed resistance to the drug. By the 1990s, several disease-producing bacteria had become resistant to penicillin and many other antibiotics. Punctuated Equilibrium Today

44. Allelic Frequency • When the frequency of alleles is the same in all its generation, the population is in genetic equilibrium and is NOT evolving. • If the allelic frequencies remain the same, phenotypes remain the same also.

45. KAIBAB AND ABERT’S SQUIRRELOnce a single tassel-eared species, time and separation by the Grand Canyon has created two subspecies. Found only on the North Rim, the Kaibab Squirrel is endangered. Abert’s is found throughout the Four Corners area. Geographic isolation

46. Sometimes mountains, lakes, or other geological features isolate a small number of individuals from the rest of a population. Over several generations, variations that do not exist in the larger population might begin to be more common in the isolated population. Also, gene mutations can occur that add variations to populations. Over time, the two populations can become so different that they no longer can breed with each other. Geographic Isolation

47. Geographic isolation same ancestors-different traits can cause speciation Grand Canyon squirrels Adaptive radiation pattern where different species develop from a common ancestor to better fit their env. Ex. migration of camels Evolve to different species

48. Traits that help living things survive in their env. Controlled by genes How do traits help them survive? Adaptation

49. Adaptive Radiation • Emergence of numerous species from a common ancestor introduced to new and diverse environments. • Example: Darwin’s Finches

50. Caused by Barriers Different env Traits change as a result of natural selection Some organisms are separated by geographical boundaries and evolve into different species. Species Variation