Chapter 15: Evolution

1. Chapter 15: Evolution

2. 15.1 Darwin’s Theory of Evolution by Natural Selection ONLY COPY UNDERLINED MATERIAL

3. Charles Darwin • Naturalist • Credited for the concept of Evolution • “Father of Evolution”

4. How it all began… • Darwin is invited on an epic journey • 1831: HMS Beagle sets sail from England to survey the coast of South America • 5 year voyage • His job was to collect biological and geological specimens during the ship’s travel. • He noticed many plants & animals were well suited to their environment.

5. Galápagos Islands • 1835: The Beagle stops at the Galápagos Islands, recently formed volcanic islands • Located 500 miles off the coast of Ecuador • Each island has a very unique climate • The animals on the islands lived nowhere else in the world, but, looked like species from South America, but these two places have different environments

6. Darwin’s Finches • Darwin found many different birds on the Islands, thinking each one was a different type of bird • He was amazed to learn that all 14 species were finches • THERE WAS ONLY 1 SPECIES ON THE MAINLAND

7. Darwin Darwin wondered - If the finches came from the mainland, why were they so different now? He suspected that populations from the mainland changed after reaching the islands Hypothesis: New species could appear through small changes in ancestral species– but how does this process work? Turned to pigeon breeders

8. Artificial Selection Previously referred to as selective breeding He learned that breeders could produce certain traits through directed breeding Darwin thought that if humans could change a species through artificial selection, then perhaps the same process could happen in nature

9. Natural Selection • Theory developed by Darwin • Explanation of how evolution works, NOT a synonym • Based on 4 principles that explain how traits change over time: • Variations • Inheritance • Overproduction • Reproductive Advantage

10. 1. Variations • Individuals in a population show differences – or variations

11. 2. Inheritance • Variations are inherited, meaning they are passed down from parent to offspring

12. 3. Overproduction • Organisms have more offspring than can survive on available resources • This creates competition, and a struggle to survive MMMMM Bunny

13. 4. Reproductive Advantage • Variations that increase reproductive success will have a greater chance of being passed on than those that do not increase reproductive success – SURVIVAL OF THE FITTEST! • Faster predator – more food, survives longer • Camouflaged prey – better protection, survives longer • Adaptations are central to this principal

14. Given enough time, natural selection modifies a population enough, and through evolution produces a new species Natural selection is ALWAYS HAPPENING!

15. Back to our Finches… • He concluded that the different beaks of each finch were inherited variations (changes) • These different beaks helped the birds compete for food, survive, and reproduce

17. Origin of Species Darwin was extremely nervous about publishing his findings, so he continued to collect evidence for his theories for many years In 1859, after 23 years, he published On the Origin of Species by Means of Natural Selection He used the term “Evolution” on the last page only This term is what biologists use today to define the changes in groups of organisms through time

18. Evolution • The changes that occur over time in the hereditary features of a species.

19. 15.2 Evidence of Evolution

20. Evolution • Remember, the theory of evolution states that we all descended from a common ancestor • How do we know evolution has happened on our planet? • Fossils • Anatomy • Homologous, Analogous, Vestigial • Embryology • Adaptations

21. Fossils • Fossil: remains of once-living things from the past • Comparing fossils from older & younger rock layers documents the fact that evolution has occurred; it is a detailed record of evolution.

22. The Fossil Record • Fossils provide a record of species that lived long ago • They show that ancient species share similarities with species that live on Earth now • Some show that some species have changed, and that some species have not changed at all

23. Anatomy Homologous structure Analogous structure • Similar structure • Different forms and functions • Inherited from a common ancestor • Different in structure and form • Similar in function • NOT inherited from a common ancestor

25. Vestigial Structures • Type of homologous structure • Shared structure that has reduced function or no function in some organisms • Evolution suggests that over time these structures will be lost

26. Vestigial Structures • Human appendix • Wisdom teeth • Tailbone (coccyx)

27. Embryology • If you look at different animals during stages of embryonic development you can see common traits. • This shows a common ancestry

28. Adaptations • Adaptation: a trait shaped by natural selection, increases an organism’s reproductive success • Fitness: how much a trait contributes to the next generation • How necessary a trait is to survival will determine if it is passed on

29. Adaptations • There are many kinds of adaptations, they can be physical or behavioral • Some adaptations are the consequences of other evolved characteristics, however, these adaptations will not increase reproductive success

30. Adaptations • The better adapted an organism is, the higher its chances of survival are • Adaptations are at the heart of Darwin’s theory!

31. Camouflage • Adaptations that allow organisms to blend in with their surroundings • Camouflage varies by species, but their environment is often the most important factor in how they appear • Become almost invisible to predators and prey

32. Mimicry • One species evolving to resemble another species

33. White-tailed Deer Fake Death When a predator approaches, their heart rate is programmed to drop so low that they enter a state of tonic immobility. The result is that the look dead, which, coupled with its involuntary peeing and pooping that accompanies the heart rate drop, will look pretty unappealing, even to a hungry animal.

34. Bloody Hippo Sweat It contains zero blood and zero sweat and yet, hippopotamuses secrete what we know as "blood sweat." This keeps their skin moist and protects it from sunburns, as well as many infections.

35. Exploding Malaysian Ant This adaptation is perhaps the most intense defense mechanism: suicide. When the ant senses its life is at risk, it will often click its own self-destruct button and explode

36. Northern Fulmar Projectile Vomit All it takes is a tiny confrontation for a fulmar chick to literally throw up chunks of orange puke that is so nasty and sticky, it becomes the foulest prey of all time Great Transformations

37. 15.3 Shaping Evolutionary Theory

38. Mechanisms of Evolution LICE Natural selection is not the only way to explain how evolution works

39. Population Genetics Every population of a species has a variety of genes, and each gene can have multiple alleles. Gene Pool: All the available genetic information within a population When life is thriving in a population and there is genetic equilibrium, then these alleles are not changing in frequency. There is no selection. There is no evolution. Everything is calm. Like apool…before the cannon ball.

40. Population Genetics Hardy-Weinberg Principle: when allele frequencies remain constant, a population is in genetic equilibrium. In other words - when the dominant genes and recessive genes are constant, the POPULATION is in equilibrium

41. Population Genetics • Evolution cannot occur if alleles in the population are not acted on by forces that cause change! Consider these forces the CANNON BALL! • Genetic drift • Gene flow • Mutation • Random mating • Natural selection • When these things are happening, evolution is happening, and Hardy-Weinberg is null and void

42. Genetic Drift • Change in the allele frequency due to chance • Founder effect, Bottleneck effect • An ant gets stepped on, a rabbit gets swept up by a tornado, an elephant drinks up a protozoa living in a puddle, a plane crashes killing a Nobel Laureate. • The above events have nothing to do with genotype or phenotype--they occurred purely by chance.

43. Genetic Drift • Founder Effect: Occurs when a small sample of a population settles in a location separated from the rest of the population • Alleles that were uncommon in the original population might be common in the new population. (so the recessives might start showing up, this happens in populations like the Amish)

44. Genetic Drift Bottleneck Effect: Occurs when a population declines to a very low number and then rebounds

45. Gene Flow • New genes entering the population, and genes leaving the population • The movement of individuals in and out of populations increases variation within a population, and decreases differences between populations

46. Mutation A change in the original DNA sequence of an organism Some have no effect, however others can lead to the creation of a different protein, which will change the phenotype

47. Natural Selection Variation of traits Inheritance Overproduction Survival of fittest

48. Speciation

49. Speciation • The formation of two species from a common ancestor • A species is a group of living things that can breed with others of the same species and form FERTILE offspring. • Allopatric, sympatric

50. Allopatric Speciation • A physical barrier divides one population into two or more populations. • Ocean, river, mountain, glacier, lava, etc. Abert squirrel Kaibab squirrel