1. How Traits Change Over Time

2. How man has changed the traits of organisms through Artificial Selection. Dogs have been breed to be friendly Cows to produce more milk Horses for speed Gold-colored fish Cats which are small and not aggressive and can play the piano?

3. If you wished to breed the fastest racehorses, how would you do it? You would probably mate your fastest male and female horses knowing their offspring should also be fast. If you continued to breed only the fastest horses generation after generation, soon you will have horses ready to race in Churchill Downs.

5. If you wished to breed the prettiest guppies, how would you do it? By only selecting the most colorful guppies and those with the longest tails, then breeding them generation after generation. wild guppies Guppy which has been selectively bred.

6. Dog breeders have been selectively breeding for desirable traits for centuries. To try your hand at artificial breeding, check out the hyperlink below. Scroll down the page to the online activity, Dog Gone Perfect Laboratories. Dog Gone Perfect Laboratories HyperlinkDog Gone Perfect Laboratories Hyperlink

7. Have you tried this activity?

8. After many generations, the offspring may look very different from their ancient ancestors.

9. Farmers have cultivated many popular vegetables from wild mustard, by artificially selecting for certain attributes.

10. In essence, when humans selectively breed organisms for certain traits, they are selecting for certain genes.

11. Charles Darwin From 1831 to 1836 Charles Darwin served as a naturalist aboard the ship H.M.S. Beagle on a British science expedition around the world. While in the Galapagos Islands in the Pacific Ocean he wondered about the origins of the many variations of plants and animals he collected there.

12. He wondered if nature could select for certain traits in the same way that man selects for certain traits. Can you find the animals in the pictures below?

13. Through observation and study, Darwin noted that organisms produce many more offspring than can possibly survive in nature. For example, salmon typically lay ~10,000 eggs, however, only a few will survive to adulthood and reproduce.

14. Putting these facts together, Darwin discovered one of the most important ideas in biology-- Natural Selection.

15. Natural Selection The idea of natural selection is a very simple one. It really comes down to two undeniable facts and one inescapable conclusion: Fact (1) Organisms vary and these variations (genes) are inherited by their offspring.

16. Thousands of frog eggs are laid in clumps in a fresh water pond. Each clump is laid by one female. Few will survive to adulthood. Apple trees produce far more seeds than could possibly survive to become full grown trees. Fact (2) Organisms produce more offspring than can possibly survive in nature. As resources become scarce, individuals must compete with each other to survive. Most organisms will not make it to adulthood, and therefore very few will breed and pass on their genes.

17. Remember this story? CHARLOTTE'S WEB ends in the springtime, as tiny spiderlings emerge from Charlotte's egg case. The gray orb spider called her egg sac her magnum opus, Latin for "great work." Charlotte told her friend Wilbur the pig that the egg sac held 514 eggs and would hatch in the spring. Her friend Wilbur the pig patiently waited, and this was his reward: Up, Up and Away! Wilbur was surprised and amazed when they hatched out, and even more surprised and amazed a few days later when they did something he'd never imagined they would do. One spring day, a warm draft of rising air blew softly through the barn cellar. The baby spiders felt the warm updraft and one of Charlotte's children climbed to the top of the fence. The spider let loose a cloud of fine silk that formed a balloon. It was time for the baby spiders to set forth as aeronauts. They were going into the world on a warm updraft to make webs for themselves. The air was soon filled with tiny balloons, each balloon carrying a spider.

18. CHARLOTTE'S WEB is fictional, but baby spiders really do balloon through the air usually by the thousands. In reality, few of those baby spiders will survive to adulthood. Many will be eaten by predators; some will not find enough to eat and starve. So what was special about those few who survive? -Maybe their coloration blended into the environment better than their brothers and sisters, so they avoided hungry birds. -Maybe they built better webs than their brothers and sisters and avoided starvation. This leads to one inescapable conclusion....

19. Inescapable conclusion: Those offspring that do survive are best adapted to their environment and will pass their genes on to their offspring. The result is, over time, populations of organisms become better adapted to their environment by this process of natural selection.

20. For example, this species of insect is well adapted (carries the right genes) to blend into its environment. Do you see the walking stick insect? It received those genes from its parents, whose genes were successful enough to allow them to survive long enough to breed.

21. Natural selection in action-- The Manchester peppered moths “Before the Industrial Revolution, the peppered moth was mostly found in a light gray form with little black speckled spots. The light-bodied moths were able to blend in with the light-colored lichens and tree bark, and the less common black moth was more likely to be eaten by birds. As a result of the common light- colored lichens and English trees, therefore, the light-colored moths were much more effective at hiding from predators, and the frequency of the dark allele was about 0.01%. Light-colored moth Dark moth

22. During the early decades of the Industrial Revolution in England, the countryside between London and Manchester was blanketed with soot from the new coal-burning factories. Many of the light-bodied lichens died from sulfur dioxide emissions, and the trees became covered with soot. This led to an increase in bird predation for light-colored moths, as they no longer blended in as well in their polluted ecosystem: indeed, their bodies now dramatically contrasted with the color of the bark. Dark-colored moths, on the other hand, were camouflaged very well by the blackened trees. Dark moths on light colored bark are easy targets for hungry birds but are hidden on pollution darkened trees.

23. Although a majority of light-colored moths initially continued to be produced, most of them didn't survive, while the dark-colored moths flourished. As a result, over the course of many generations of moths, the allele frequency gradually shifted towards the dominant allele, as more and more dark-bodied moths survived to reproduce. By the mid-19th century, the number of dark-colored moths had risen noticeably, and by 1895, the percentage of dark-colored moths in the Manchester peppered moth population was reported at 98%, a dramatic change (by almost 1000%) from the original frequency. In modern times, due to cleaner air standards, the dark-bodied moth is becoming less frequent, again demonstrating the adaptive shifts in the peppered moth population.” -From Wikipedia, the free encyclopedia

24. Natural selection in action-- The Manchester peppered moths Click the hyperlink below and go to the natural selection simulation game. peppered moth simulation game **Run Lichen (light colored) forest link. Record your results. **Run Soot (dark colored) forest link. Record your results. Note

25. Another example of natural selection at work (click below to watch video clip) Note: Turn caption on while viewing

26. Natural Selection (in summary) 1. Organisms vary and these variations (genes) are inherited by their offspring. 2. Organisms produce more offspring than can possibly survive in nature. 3.Those offspring that do survive are best adapted to their environment and will pass their genes on to their offspring. The result is, over time, populations of organisms become better adapted to their environment by this process of natural selection.

27. Evolution means change over time. Cars have changed over time. Computers have changed over time. Video games have changed over time. pong

28. Evolution Darwin’s idea describes how life can change over time through the mechanism of natural selection.

29. Evolution is a slow process. It is important to understand individual organisms do not change (adapt) over time. In general, individuals are either well adapted (have the right genes) or die before passing on their genes. Only populations of organisms evolve.

30. Environments change over time. Due to the movement of continents and global climate change, environments are constantly changing; putting constant pressure on populations to evolve.

31. Populations are constantly evolving ( The Eternal Arms Race) Click on the video below to see an interesting case of an evolving arms race.

32. Assignment Describe the evolutionary arms race between the poisonous newt and the poison tolerant garner snake in terms of natural selection. (See next slide for a reminder)

33. Natural Selection (in summary) (apply these 3 ideas to your assignment) 1. Organisms vary and these variations (genes) are inherited by their offspring. 2. Organisms produce more offspring than can possibly survive in nature. 3.Those offspring that do survive are best adapted to their environment and will pass their genes on to their offspring. The result is, over time, populations of organisms become better adapted to their environment by this process of natural selection.

34. Why is it important to know about evolution? What evolution means to us

35. The eternal arms race- microbes versus medicine click on the picture below to watch the video

36. Evolution by natural selection is a central concept in biology. While natural selection is a simple process to understand, as it exerts it’s influence over geologic time it’s implications are far-reaching, subtle and profound. It explains the unity of life and is responsible for the enormous diversity of life on our planet.

37. "Nothing in biology makes sense except in the light of evolution." -Theodosius Dobzhansky, Geneticist

38. Do the natural selection web lab. (click on the screen below)