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Evolution and Adaptations

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Presentation on theme: "Evolution and Adaptations"— Presentation transcript:

1 Evolution and Adaptations

2 Evolution Simple Definition – change over time
Complicated Definition – process by which modern organisms have descended from ancient organisms

3 History of Evolution Charles Darwin Flunked out of medical school
Sailed around the world on a boat called the HMS Beagle Made many observations about animals around the world and collected evidence that led him to propose his hypothesis. Birds, Tortoises Concluded that Evolution happened because of Natural Selection

4 Darwin’s Observations
Living Organisms and Fossils Collected and preserved fossils Noticed that some fossils resembled organisms that were in existence and some were not like any other animal he had ever seen

5 Darwin’s Observations
Darwin observed 3 different types of tortoises on the Galapogas. What kinds of plants do you think the saddle tortoise might eat vs. the domed tortoise?

6 Scientists who influenced Darwin
James Hutton and Charles Lyell Their research showing that earth was millions of years old and that the surface/ features of earth had been changing for millions of years helped support/ develop Darwin’s crazy new idea that the appearances of animals had been changing throughout time as well.

7 Who else was thinking about evolution?
Jean Baptiste Lamarck

8 Jean Baptiste Lamarck Disagreed with Darwin
Said that Evolution happened because of TRAITS that organisms ACQUIRED during their lifetime Theory of Use/ Disuse – proposed that by selective USE or DISUSE of structures/ organs, organisms acquired or lost traits during their lifetime These Acquired or Lost traits could then be passed on to the offspring

9 Why Lamarck was wrong p.425 Vestigial Structures
Humans have an appendix – used to be used for digestion, but now it has no real purpose in the body, but we are still born with an appendix Snakes have a pelvic bone and leg attachments in their skeletons, but they do not walk and they do not have legs – it is believed that snakes developed from crawling reptiles

10 Acquired Traits

11 Artificial Selection vs. Natural Selection
Artificial Selection – purposefully breeding organisms that have the best traits Farmers will breed the best cows in order to get the best meat or milk Natural Selection – organisms that are most adapted to their environment will mate with each other to pass on their genes to the next generation Have the greatest fitness


13 Natural Selection Definition – process by which traits become MORE or LESS common in a population 4 principles of Natural Selection Variation – individuals in a population are different from one another Heritability – variations are inherited from parents Overproduction – populations produce more offspring than can survive Reproductive Advantage – some variations allow organisms to have more babies than others

14 Survival of the Fittest
Fitness – an organisms ability to survive on its own and to produce viable offspring More fitness an organism has, the better chances it has to pass on its genes to the next generation Adaptation – any inherited characteristic that increases an organism’s chance of survival – increases its fitness

15 Patterns of Natural Selection
When populations change in physical characteristics due to Natural Selection, they exhibit 1 of 3 different graph distributions Directional Selection – 1 of the extreme traits is selected for – ex really tall people become more numerous than short people Disruptional Selection – Both extremes are selected FOR and the average of the 2 traits is selected AGAINST – ex really tall people and really short people become more numerous than average-height people Stabilizing Selection – The average trait is more favorable and the extreme traits are selected against – ex in a population of short, medium and tall people, you would expect to see more medium-sized people over time



18 Evidences of Evolution

19 Can you pick out the misconceptions regarding evolution?
Charles Darwin developed the theory of evolution. Scientists believe in evolution. Humans evolved from monkeys. Scientists regularly debate whether evolution happens. Evolution as a science deals with the origins of life on Earth.

20 5 pieces of Evidence to support Evolution

21 Evidence 1: Homology

22 Homology Structures in different species that have a common evolutionary ancestry or a common developmental ancestry. They may or may not have the same function in both species. Can you think of some homologous structures? Remember the animals must be related.

23 What in this picture shows evidence of homology?

24 How are these animals related?

25 Analogous Structures Structures that have the same function and might look the same, but are NOT inherited from a common ancestor Ex Wings – insects and birds

26 Homology or Analogy Whales are mammals and sharks are not, yet they both have fins for swimming – are these structures Analogous or Homologous? A duckbill platypus has fur, so does a polar bear – are these structures analogous or homologous?

27 Evidence 2: Comparative Embryology

28 What relationship exists?
If a structure existed before another structure in evolutionary terms, it will also appear earlier in the embryo’s development. Species which have an evolutionary relationship typically share the early stages of embryonal development and differ in later stages.


30 Evidence 3: Genetics and DNA Similarities (Molecular Evidence)

31 Molecular Genetics provides direct evidence to evolution.
What we know… All cells rely on DNA to make proteins. Using new technologies, biologists are able to determine the amino acid sequences in proteins to determine evolutionary relationships among various species of organisms.  The more closely related two species are, the greater the similarity in amino acid sequences of their proteins. Molecular Genetics provides direct evidence to evolution.

32 For example:

33 Evidence 4: Fossil Record

34 Paleontology is the Key
The discovery of fossils showing forms of animals never previously seen. Fossils provide direct evidence of the history of evolution. Darwin saw fossils of animals that were similar to one’s that he had seen before, but weren’t exactly the same

35 Evolution of Horses Horses do not look the same as they did many years ago Fossil Record shows evidence that animals have changed over time and that they share a common ancestor based on similarities in their skeletons.

36 Evidence 5: Biogeography

37 Historical Biogeography
Concerned with the origins and histories of species Fossil records Cladograms

38 http://www. cartage. org

39 Continental Drift Alfred Wegener Plate Tectonics
The case of the mesosaurus

40 Mesosaurus

41 How fast can evolution happen?
Gradualism - very small changes over long periods of time Punctuated Equilibrium - catastrophic events cause rapid evolution in very short amounts of time

42 Gradualism and Punctuated Equilibrium

43 Adaptations Definition – trait shaped by natural selection that increases and organism’s reproductive success More simply – a body part, body covering, or behavior that helps an organism survive its environment Type of Adaptations Animals Camouflage, Mimicry Plants Antimicrobial Resistance

44 Animal Adaptations

45 Mimicry - adaptation in which one species evolves to resemble another species for protection or other advantages

46 Animal Adaptations Fur Color - camouflage

47 Camouflage – adaptation that allow organisms to blend into to other structures

48 Camouflage

49 Camouflage – counter-shading

50 Plant Adaptations

51 Plants adapt to their environment
Thorns To stop animals from eating them Thick stems and leaves To hold water Shape Hold water, attract insects Smell Attract and Deter Bright Colors Creative Seeds To be carried by animals, water or wind

52 Sweet Gum Tree – Seed Pods

53 Maple Trees – helicopter seeds

54 Dandelions

55 Piture Plant

56 Bromelliad

57 Cactus

58 Succulent

59 Fragrant Flowers

60 Fragrant Flowers

61 Brightly-colored Flowers

62 Brightly-colored Flowers

63 Adaptations that help plants grow
Tropisms Adaptations that help plants grow

64 4 Tropisms Thigmotropism Phototropism Gravitropism Hydrotropism

65 Thigmotropism How certain plants can grow and attach to things that they touch

66 Phototropism Growth of a plant towards sunlight


68 Gravitropism - helps the roots grow down and the stems to grow up


70 Hydrotropism – growth of roots toward their water source

71 Biological Resistance
Antibiotics and Pesticides have been used to kill unwanted insects, bateria and fungi Some of these organisms do not die when exposed to the pesticides or antibiotics This makes them RESISTANT. The RESISTANT organism then can pass on its genes and RESISTANCE to future generations, causing the current “POISON” to be ineffective

72 Antibiotic Use Antibiotics used to be very effective
However, people would stop taking the antibiotic when they started feeling better …..but, not all of the bacteria were killed….so those bacteria that lived had been exposed to the antibiotic and developed a resistance to it The resistance was passed on to the next generations….making the antibiotic ineffective Always finish a prescription that is an ANTIBIOTIC

73 Patterns of Evolution Coevolution Convergent Evolution
Adaptive Radiation (Divergent Evolution) Very short time – one species gives rise to many species in response to the creation of a new habitat or ecological opportunity Coevolution Different species evolve in response to one another Convergent Evolution Unrelated species evolve similar traits even though they are in different parts of the world

74 Adaptive Radiation

75 Adaptive Radiation – all of these birds share a common ancestor

76 Co-Evolution

77 Co-evolution – Yucca Moth and Yucca Plant
Yucca flowers are a certain shape so only that tiny moth can pollinate them. The moths lay their eggs in the yucca flowers and the larvae (caterpillars) live in the developing ovary and eat yucca seeds.

78 Convergent Evolution – similar noses, but different species

79 Convergent Evolution – 2 different types of foxes that look similar because they both live in the desert

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