Unit 6 Evolution

1. Unit 6 Evolution

2. Questions about life • Where did all the diff organisms come from on earth? • How are they related? • What kind of explanation could answer these questions?

3. Answers • Evolution – change over time, the process that modern organisms changed from ancient organisms • Theory – well supported and testable explanation for a phenomenon

4. Charles Darwin English biologist Born Feb. 12th 1809 Went to college and then went on a trip to explore the world

6. HMS Beagle • This was Darwin’s Ship • While sailing every place Darwin stopped he would document observations about the living things • He would also collect examples • Patterns he noticed • Each animal and plant was suited for their environment • Ex: reproduction, eating, camouflage ect. • Also saw that animals he knew (England) would survive there as well but they were not around • Why?

7. Fossils • Darwin realized he needed to look back at the past instead of the now • Started collecting fossils as well

9. The Galapagos Islands • Good view at many climates • And many different Environments • What he noticed • Birds • Most of the birds looked the same on each island • The difference was the beaks

11. The birds had adapted to fit a food source • The different beaks gave them something that they could use to eat different things • Ex: Short Broad Beak = Power to crush seeds • Ex: Long skinny beak = ability to get bugs out of dirt and trees

12. Land Tortoises 1. Noticed that by their shells you could identify the Island they were from.

13. The Trip Home • Looked at all of his findings • Noticed that characteristics of animals changed from island to island • Thought maybe once were all the same • But have adapted to what they were now • Diff. Environment = diff. characteristics

14. People other than Darwin

15. People other than Darwin • Hutton and Lyell • Studied earth’s surface • Gathered info suggesting earth was very old and changed over time a. Much more than 2000 years like everybody thought • Thought maybe the same was true about life

17. Lamark’s Evolution Hypothesis • Proposed that by selective use organisms aquired or lost traits during their lifetime • These traits would then be passed on to offspring • Ex: Birds developed wings • Said they tried to fly away • And after lots of trying they built up the muscle to use their arms (wings) for flight. • Ex: body builders

19. Tomas Malthus • An English economist • Noticed that babies were being born faster than people dying • So eventually the living space and food wouldn’t support the population • Realized the only thing that stopped this was war, famine, and disease

20. Darwin thought this applied to plants as well • 1 plant produces 1000s of seeds each year • But we were not over run with plants • So what killed them and let the ones around survive?

21. Darwin’s Findings • Main Points • Although most things he collected looked similar to things people knew about • None were the same • And most were found in only one spot (island)

22. Origin of Species • Book of his notes that was published • It proposed a mechanism for evolution called natural selection • Presented evidence that organisms had changed over millions of years

23. Inherited Variations & Artificial Selection • Inherited traits: • Some plants have larger fruits • Some animals (cows) produce more milk • So genetically these traits are passed on • Artificial selection • People affect genetic variations • Breed cows for best size, milk, ect… • Racing horses are bred for speed • Artificial selection – the selective breeding done with animals by humans for most desired traits.

24. Evolution by Natural Selection • Struggle for existence: • Means members of each species compete to obtain food, living space and other needs • In this struggle the predators have an advantage • The prey must become faster, better camouflaged or better protected

32. Survival of the fittest • Fitness – ability of an individual to survive and reproduce • Is a result of adaptations • Adaptation – any inherited characteristic that increases a chance of survival • Can be anatomical, structural, etc… • Ex: porcupine, hunting in groups, photosynthesis • All individuals differ from species • Have unique advantages and disadvantages • If it’s an advantage = live • If it’s a disadvantage = die

33. Natural selection – what Darwin called survival of the fittest • Natures way of selecting species • Descent with modification • Darwin proposed natural selection produces different niches • Common Descent principle – says that everything is from a common ancestor

34. Evidence of Evolution • Fossil record • Can look at older fossils and see evolution • Geographic Distribution • Organisms have similar characteristics in different regions • Coypu and Muskrat • Same pressure on organisms so they developed differently but similar

35. Skeletons

37. Homologous Body structures • Animals like reptiles, birds and mammals have different appendages but similar bones • Homologous structures – different mature forms but develop from same tissues • Vestigial organs – remains of homologous organ that is reduced in size • Wasn’t used and disappeared or disappearing • Ex: Appendix • Embryology • Embryos develop similarly • Tissues, organs, and cells develop in almost same order

40. End of Chapter Notes