Mechanisms of Evolution How does evolution work?

1. Mechanisms of EvolutionHow does evolution work?

2. What do YOU think of when you hear the word EVOLUTION…

3. *DISCLAIMER* • We are teaching what SCIENCE says about evolution/ specifically natural selection • There have been, especially in recent years, many misconceptions about what this whole concept really states.

4. *MORE DISCLAIMER* • I am NOT telling you what you have to believe. I am giving you one viewpoint. Knowing BOTH SIDES of any argument is IMPERITIVE if this is something you are passionate about. Evolution by natural selection is a theroy…just like gravity and heliocentrism and oxygen combustion…

5. Origins of Life • Spontaneous Generation • Life arises from non-life • Francesco Redi disproved this theroy, but his meat experiments were not well accepted • Biogenesis • Life begets life, life has to come from life • Louis Pasteur proved this with broth experiment

6. A Modern Idea • Primordial Soup Hypothesis • Oparin & Haldane (1920’s) • Earth contained organic molecules, lightning & sun’s UV energy gave way to 1st life in chem. Reactions. • Miller and Urey • Supported Oparin & Haldan, showed in a lab that the theroy worked! • https://www.youtube.com/watch?v=TYCf1iQifuQ

8. Origins of Life • People debate about how different life forms develop. • New life forms after a natural disaster. • Experiences affected genes that were passed on to offspring. • Charles Bonnet (mid-1700’s) 1st coined the word evolution. • *evolution: change over time

9. Lamark • John Baptiste Lamark: 3 ideas of evolution – published in 1809: • Organisms constantly strive to improve themselves • Most used body structures stay, unused waste away • Offspring inherit new characteristics that “developed” • Lamark’s theory was later disproved

10. Lamarkism

11. Question Time! • What will you be doing when you are 22? Where do you see yourself? • College/Tech School • Working • Traveling • Other???

12. Charles Darwin • When he was 22….. • Naturalist on HMS Beagle • Studied animals in the Galapagos Islands

13. HMS Beagle • Set sail in 1831- took 5 years to circumnavigate the globe!

14. Galapagos Islands • Darwin noticed that birds on neighboring islands were similar • They had different beak styles that helped them eat the food present on their island!

16. Darwin • Animals suited for survival will reproduce • Animals not suited for survival will die • Darwin studied many different organisms over a period of 13 years. He developed his theory of natural selection.

17. What is natural selection? • “Survival of the fittest” • PLEASE NOTE!!!! • Darwin wrote the book “On the Origin of Species” NOWHERE in this book does it say ANYTHING about monkeys and people!!!!!!!!!!!!

18. Darwin’s Theroy: The step process by which evolution occurs. Natural Selection 5

19. Natural Selection: Five Parts • Genetic Variation - Within one population, genetic differences already exist Example: giraffes are born with genes for varying neck lengths

20. Natural Selection: Five Parts 2. Competition: • individuals must evadepredators and compete for food, living space and mates Example: not enough leaves to feed all the giraffes not all giraffes can reach the leaves

21. Natural Selection: Five Parts 3. Survival of the fittest: • Only some individuals will survive and reproduce; those with adaptive traits • traits that help them survive better in that environment Example: giraffes with longer necks will get more food, survive longer and reproduce more passing on their gene for long necks

22. 4. Population Frequency: - over time, population will shift to having more individuals withadaptive traits Natural Selection: Five Parts Example: over time, more long-necked giraffes

23. Natural Selection: Five Parts 5. Adaptation/Speciation: • Over time, a population changes; adapting to it’s environment • Might become so different from the original species that it becomes a new species • The environment determines which traits are “selected” • Example: because the environment had only tall trees, long-necked giraffes were better suited for survival and reproduction

24. Putting the Pieces Together Struggle for survival – organisms compete with each other for resources Survival of the fittest – individuals better adapted to the environment more likely to survive, reproduce and pass on more genes Natural selection- a population will change over time to become better adapted to their environment

25. Peppered Moths • Industrial Melanism- darkening of organisms in response to human caused changes in the environment due to industry • LAB!!!

26. EVOLUTION • Evolution is change over time • Cumulative changes in groups of organisms throughout time. • Natural selection is a mechanism by which evolution occurs • https://www.youtube.com/watch?v=K4S2qJboi4I

27. When Populations Won’t Change -Determining conditions in which evolution will not happen helps scientists understand when evolution will happen. Hardy-Weinberg Principle: the genes found in a population won’t change unless one or more factors cause a change. -Genetic Equilibrium: when the genes don’t change, -If the genes don’t change, the population won’t evolve

28. When Populations Won’t Change Hardy-Weinberg’s Five Conditions Required to Maintain Genetic Equilibrium 1. There must be random mating 2. The population must be very large 3. There can be no movement into or out of the population 4. No mutations 5. No natural selection

29. When Populations Won’t Change Hardy-Weinberg’s Five Conditions Required to Maintain Genetic Equilibrium 1. There must be random mating 2. The population must be very large 3. There can be no movement into or out of the population 4. No mutations 5. No natural selection

30. Evidence for Evolution • 6 different ways!

31. Tracking Changes in Organisms • The analysis of fossils and modern organisms gives support to evolution. • Fossils • The fossil record is useful • Unfortunately the fossil record is incomplete because: • conditions must be “just right” for fossils to form • only the ones discovered are of any use #1

32. Modern Organisms • 3 Types of Structural similarities can occur in organisms: • Homologous Structures • Vestigial Structures • Analogous Structures

33. Homologous Structures • Similar structures found in different species • Similar because the species share a common ancestor • Different because each species adapted to a different niche • Ex. Human arm, whale fin, and bat wing #2

35. Vestigial structure • Structure in an organism that has no apparent use • Suggest structures that were useful to ancestors • Ex. Hip and leg bones in snakes • Pelvis bone in whales • Human appendix and tailbone #3

36. Analogous structures • Structures that have the same function in different organisms, but are not inherited from a common ancestor • Insect wings and bird wings #4

37. Embryology Evidence • Embryos of related organisms are very much alike • Ex. All vertebrate (backbone) embryos have gill pouches • In fish they become gills, in mammals they become eustachian tubes #5

38. Guess the Embryo! https://www.youtube.com/watch?v=uAZmLYWEPGk

39. DNA BASES • All living things share biochemical characteristics: use of ATP, DNA bases, amino acids • more closely related species share more base sequences of DNA #6

40. How do we map out these changes? • Evolutionary relationships are represented by Diagrams called cladograms (branching diagrams that organize relationships)

41. Reading Cladograms • When an ancestral lineage splits: speciation is indicated due to the “arrival” of some new trait. Each lineage has unique traits to itself alone and traits that are shared with other lineages. each lineage has ancestors that are unique to that lineage and ancestors that are shared with other lineages — common ancestors. Read like a family tree: show patterns of shared ancestry between lineages.

42. Quick Question • A group that includes a common ancestor and all the descendants (living and extinct) of that ancestor. What do you think a clade is?

43. Reading Cladogram: Identifying Clades • Imagine clipping a single branch off the phylogeny • all of the organisms on that pruned branch make up a clade Using a cladogram, it is easy to tell if a group of lineages forms a clade.

44. Quick Question • Looking at the image to the right: • Is the green box a clade? • The blue? • The pink? • The orange?

45. Reading Cladograms: Clades • Clades are nested within one another • they form a nested hierarchy. • A clade may include many thousands of species or just a few.

46. Interpreting Cladograms it's easy to misinterpret cladograms as implying that some organisms are more "advanced" than others however, cladograms don't imply this at all. when reading a cladogram, it is important to keep three things in mind

47. (mis)Interpreting Cladograms: One Evolution produces a pattern of relationships among lineages that is tree-like, not ladder-like.

48. (mis)Interpreting Cladograms: Two Just because we tend to read phylogenies from left to right, there is no correlation with level of "advancement."

49. (mis)Interpreting Cladograms: Three For any speciation event on a phylogeny, the choice of which lineage goes to the right and which goes to the left is arbitrary. The following phylogenies are equivalent:

50. Interpreting Phylogenies: Human Example • The points described above cause the most problems when it comes to human evolution. • It is important to remember that: • Humans did not evolve from chimpanzees. Humans and chimpanzees are evolutionary cousins and share a recent common ancestor that was neither chimpanzee nor human. • Humans are not "higher" or "more evolved" than other living lineages. Since our lineages split, humans and chimpanzees have each evolved traits unique to their own lineages.