Evolution

1. Evolution Textbook chapter 16

2. Such varied Honeycreepers • The misty rain forests on the Hawaiian island of Kauai is home to birds found nowhere else on earth • Why is there such a variation of honeycreepers?

3. Enter Chuck Darwin… • Born in 1809 • Sailed around the world in 1831 on the HMS Beagle • Noted similarities and differences among the finches (birds) and tortoises on Galapagos Islands with those in South America

4. Charles Darwin • Led Darwin to develop what has been called the “Best Idea Anyone’s Ever Had”—his theory of evolution • He hypothesized the animals adapted to local conditions on the islands after their arrival

5. Darwin’s Observations • Patterns of Diversity—wondered by different continents with similar habitats had very different animals. EX. Why were there no rabbits in Australia or kangaroos in Europe?

6. Darwin’s Observations • Living Organisms and Fossils—Why were so many species extinct and why do they seem related to living species?

7. Darwin’s Observations • The Galapagos Islands—The islands were close together, yet each had different climates. As a result each had its own unique animal life

8. Voyage of the Beagle • Darwin came to 3 conclusions: • Species vary globally • Species vary locally • Species vary over time

9. Species Vary Globally • Different, yet ecologically similar, animal species inhabited separate, but ecologically similar, habitats around the globe • EX. Rheas of South America vs. Ostriches of Africa vs. Emus of Australia

10. Species Vary Locally • Different, yet related, animal species often occupied different habitats within a local area • EX. Tortoises on Isabela and Hood Islands within the Galapagos

11. Species Vary Over time • Darwin collected fossilsin addition to specimens • Darwin noticed that some fossils of extinct animals were similar to living species • EX. Armadillo vs Glyptodont

12. The Science of Darwin’s Day • Most European’s in the early 1800s believed Earth was only a few thousand years old, and that it hadn’t changed much since • By the mid 1800s, geology provided evidence about the history of Earth • James Hutton and Charles Lyell concluded that the Earth is extremely old and that the processes that changed Earth in the past and the same that operate in the present

13. Hutton & Lyell

14. Lamarck’s Evolutionary Hypotheses • Darwin wasn’t the first to suggest characteristics of a species could change over time, but the ideas on how the changed happened was different • Jean-Baptiste Lamarck proposed the first hypothesis of evolution 1809

15. Lamarck’s Evolutionary Hypotheses • “Tendency toward perfection”—Organisms willed themselves to change by using or not using certain body parts • “Use or disuse”—Organisms acquired traits during their life by the use or disuse of organs. These new traits could then be passed on to offspring • “Inheritance of acquired traits”—Traits acquired during life were passed on to offspring

16. Lamarck’s Evolutionary Hypotheses

17. Thomas Malthus • In 1798, Thomas Malthus noted that humans were being born faster than people were dying • Reasoned that if the human population grew unchecked, there wouldn’t be enough living space • Believed the only forces that worked against growth were war, famine, and disease • Darwin realized that this idea applied more to other organisms than it did to humans

18. Darwin’s findings • Darwin published his book “The Origin of Species” in 1859

19. Darwin’s Natural Selection Worksheet #2. There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones with medium coats. It is fall, soon to be winter. The temperatures are dropping rapidly and the bears must be kept warm, or they will freeze to death. Many of the bears have ~ (about) 2 cubs each but due to the extreme temperatures, many mothers only have one cub left.

20. #2. There are 3 types of polar bears: ones with thick coats, ones with thin coats and ones with medium coats. It is fall, soon to be winter. The temperatures are dropping rapidly and the bears must be kept warm, or they will freeze to death. Many of the bears have ~ (about) 2 cubs each but due to the extreme temperatures, many mothers only have one cub left. Overpopulation? 1 out of 2 cubs survive Variation? Thick, thin, & medium coats Struggle for Existence? Extreme Temperatures Natural Selection? Thick-coated bears will survive

21. Darwin & Evolution Stations • Why? • Become more familiar with the scientists that influenced Darwin • Understand Darwin’s Theory of Evolution • Evaluate situations and apply the parts of Darwin’s Evolution • WORKING IN PAIRS (THAT MEANS 2!) • 3 MINUTES PER STATION • ANY REMAINING CLASS TIME WILL BE USED TO FINISHED INCOMPLETE STATIONS (IF NO TIME LEFT, STATIONS WILL BE FINISHED TOMORROW)

22. Patterns of Natural Selection • All patterns of natural selection are based on a distribution (bell) curve

23. Directional selection • Natural selection in which an extreme phenotype is favored over other phenotypes, causing the alleles causing that phenotype to be favored and shift over time in the direction of that phenotypes Directional selection selects for one extreme trait and against the other extreme

24. Directional Selection Example • Prior to the industrial revolution in England the peppered moth had light coloration and lived on trees covered with light-colored lichen. This provided camouflage against predatory birds. There were a few dark individuals in the population, but they were usually eaten by birds. However, once the Industrial Revolution began the light-colored lichens covering the trees were killed by emissions from the new factories. Without the light background of the trees, the light moths were more visible to the birds and now the dark moths had a camouflage advantage.

25. Stabilizing selection • Natural selection in which intermediate forms of a trait are favored and more extreme values are selected against. Stabilizing selection selects for moderate traits and against both extremes

26. Stabilizing Selection Example • Human birth weight has undergone stabilizing selection. Babies of low birth weight lose heat more quickly and get ill from infectious diseases more easily, whereas babies of large body weight are more difficult to deliver through the pelvis. Infants of a more medium weight have the greatest chance of survival.

27. disruptive selection • Natural selection in which extreme forms of a trait are favored over intermediate values. Variance of the trait increases and the population becomes divided phenotypically into two distinct groups Disruptive selection selects for both extremes and against moderate traits

28. Disruptive Selection Example • A population of mice lives in a desert habitat with both sand and black volcanic rocks. The mice with black fur are able to hide from predators amongst the black rocks, and the mice with lighter fur are able to hide from predators in the sand. The mice with intermediate fur, however, stand out in all areas of the habitat, and thereby are killed by predators.

29. Patterns of evolution • Convergent Evolution • Divergent Evolution • Coevolution • Punctuated Equilibrium

30. Convergent evolution • 2 or more distinct species share traits NOT due to a common ancestor • Even though species look similar, they are NOT related!!

31. Divergent Evolution • 2 or more species evolve from a common ancestor

32. Coevolution • 2 or more species affect each other’s evolution • Likely to happen when different species have close ecological relationships with each other: • Predator/Prey or Parasite/Host • Competitive Species • Mutualistic Species (both species benefit from the interaction)

33. Punctuated Equilibrium • Species remain the same for a long period of time • Sudden large change in a short period of time • Results in rapid evolution • Eliminates the need for “Links”

34. The Process of Speciation • Species—group of organisms that breed with one another and produce fertile offspring • Because populations share a gene pool, a genetic change in one individual can spread through the population

35. Isolating Mechanisms • As new species evolve, populations get reproductively isolated from one another • Reproductive Isolationcan happen in 3 ways: • Behavioral Isolation • Geographic Isolation • Temporal Isolation

36. Behavioral Isolation • Two populations are capable of interbreeding but have differences in behaviors

37. Geographic Isolation • Two populations are separated by a geographical barrier • Geographical barriers do not always mean formation of a new species!

38. Temporal Isolation • Two or more species reproduce at different times • Example: 3 species of orchid all live in the same forest. Each species releases pollen on a different day—because of this they cannot pollinate each other

39. EXAMPLES • Two species of fireflies come out between the hours of 9-11pm. Each species has a unique pattern of flashes that attracts a mate • Behavioral

40. EXAMPLES • Two species of plants sprout from the ground at different months in the year • Temporal

41. EXAMPLES • Two species of squirrels get stranded on either side of the Grand Canyon • Geographic

42. EXAMPLES • Two species of mountain lions live in a forest on either side of a large river • Geographic

43. EXAMPLES • Two species bowerbirds call from a tree for a potential mate • Behavioral

44. 1. Porcupines in the United States have quills (spines) that are attached to their skins. When they feel threatened, they can tense up their bodies, causing the quills to “shoot out”. These spiny quills can pierce the skin of attacking animals, causing injury and pain. Although not closely related to the porcupine, hedgehogs that live throughout parts of Europe also have protective spines that they use to defend themselves from attacking animals. Convergent Evolution—porcupines and hedgehogs are NOT related, but they have common characteristics

45. 2. King Snakes are a family of snakes that usually eat other snakes in the wild. Even though many of the snakes they eat are poisonous, King Snakes have adapted the ability to not be affected by their poisons. In response, some of these poisonous snakes, like rattle snakes, have adapted other defensive behaviors (other than biting) to try and “scare off” the King Snakes. Coevolution—the two types of snakes are evolving in response to each other

46. 3. River otters that live in South American rivers eat fish and other small creatures they can capture. These animals have become reproductively isolated from the closely related sea otter, who live in the ocean waters along the Pacific coast, many thousands of miles away. Geographic Isolation—one group lives in South American rivers and the other lives along the Pacific coast

47. 4. The flowers that bloom from the saguaro cactus have evolved a bright, white coloration to attract many of the bats they rely on to pollinate their flowers. Since they rely on the bats, they have also adapted to opening their flowers at night, when the bats are active. The bats have also adapted to the cactus by a.) developing the ability to hover above the flowers, and b.) developing a long tongue that can reach deep inside the flower. Coevolution—the flowers rely on the bats to spread pollen and the bats rely on the flowers for food

48. 5. Chameleons, a type of lizard (reptile), have two eyes they can move in completely different directions, so they can see all the way around themselves. Sand lances are a type of fish that can also move their eyes like the chameleon, even though they are not related to one another. Convergent Evolution—chameleons and sand lances share common characteristics, but NOT any common ancestors

49. 6. In the United States, there are several species of poisonous scorpions that all evolved from one common ancestor. The scorpion species each occupy slightly different niches, and none of them can reproduce with one another. Divergent Evolution—Different species of scorpions have a common ancestor

50. 7. Octopus and squid live in seas throughout the world. Both have mouths with beaks with which they use to cut and eat their prey. These beaks are much like a parrot’s, which are birds that live among the trees of tropical forests. Convergent Evolution—octopi and squids are NOT related to parrots, yet they have similar characteristics