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Www.cengage.com/biology/starr Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 16 Evidence of Evolution (Sections 16.6 -

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Presentation on theme: "Www.cengage.com/biology/starr Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 16 Evidence of Evolution (Sections 16.6 -"— Presentation transcript:

1 Albia Dugger Miami Dade College Cecie Starr Christine Evers Lisa Starr Chapter 16 Evidence of Evolution (Sections )

2 16.6 Putting Time Into Perspective Transitions in the fossil record are boundaries for great intervals of the geologic time scale geologic time scale Chronology of Earth’s history Correlates geologic and evolutionary events

3 The Geologic Time Scale

4 Sedimentary Rock in the Grand Canyon

5 ANIMATION: Geologic time scale To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

6 Key Concepts Evidence From Fossils The fossil record provides physical evidence of past changes in many lines of descent We use the property of radioisotope decay to determine the age of rocks and fossils

7 16.7 Drifting Continents, Changing Seas The theory that all continents today were once part of the supercontinent Pangea explains why the same fossils occur in sedimentary rock on both sides of the Atlantic Ocean Pangea Supercontinent that formed about 237 million years ago and broke up about 152 million years ago

8 Plate Tectonics Movements of Earth’s tectonic plates carry land masses to new positions, which have profound impacts on evolution plate tectonics Theory that Earth’s outer layer of rock is cracked into plates, the slow movement of which rafts continents to new locations over geologic time Supported by magnetic polarity of igneous rocks

9 Mechanisms of Plate Tectonics New crust spreads outward from oceanic ridges, forcing tectonic plates away from the ridge and into trenches

10 Fig , p. 248 faulthot spottrench ridge 1234 Mechanisms of Plate Tectonics

11 ANIMATION: Plate margins To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

12 An Older Supercontinent Identical layers of rock around the Southern Hemisphere hold matching fossils of organisms that were extinct millions of years before Pangea formed An older supercontinent, Gondwana, included most land masses that are now in the Southern Hemisphere, India and Arabia Gondwana Supercontinent that existed before Pangea, more than 500 million years ago

13 The Drifting Continents Major evolutionary forces: Gondwana broke up in the Silurian Pangea formed in the Triassic, broke up in the Jurassic

14 Key Concepts Evidence From Biogeography Geologic events have influenced evolution Correlating geologic and evolutionary events helps explain the distribution of species, past and present

15 16.8 Similarities in Body Form and Function Clues about the history of a lineage may be found in body form, function, or biochemistry Similarities in structure of body parts often reflect shared ancestry – in such cases, comparative morphology can be used to unravel evolutionary relationships

16 Morphological Divergence Homologous structures (body parts that appear different in different lineages, but are similar in some underlying aspect of form) are evidence of a common ancestor Body parts become modified to a different size, shape, or function in different lineages by morphological divergence Example: Limb bones of all modern land vertebrates originated from a family of ancient “stem reptiles”

17 Key Terms homologous structures Similar body parts that evolved in a common ancestor morphological divergence Evolutionary pattern in which a body part of an ancestor changes in its descendants

18 Morphological Divergence Number and position of many skeletal elements were preserved when diverse forms evolved Certain bones were lost over time in some of the lineages

19 Fig , p. 250 elephant human bat porpoise penguin chicken pterosaur stem reptile Morphological Divergence

20 Morphological Convergence Analogous structures are body parts that look alike in different lineages but did not evolve in a common ancestor They evolved separately after the lineages diverged (as adaptations to the same environmental pressures) by the process of morphological convergence Example: Bird, bat, and insect wings all perform the same function (flight) but the wing structures are not homologous

21 Key Terms analogous structures Similar body structures that evolved separately in different lineages morphological convergence Evolutionary pattern in which similar body parts evolve separately in different lineages

22 Morphological Convergence

23 Fig a, p. 251 Morphological Convergence

24 Fig b, p. 251 Morphological Convergence

25 Fig c, p. 251 Morphological Convergence

26 Fig d, p. 251 Morphological Convergence

27 Fig d, p. 251 InsectsBatsHumansCrocodilesBirds wings limbs with 5 digits D Morphological Convergence

28 16.9 Similarities in Patterns of Development Similar patterns of embryonic development reflect shared ancestry Master genes that control embryonic development patterns have changed very little or not at all over evolutionary time Master genes with similar sequence and function in different lineages are strong evidence that those lineages are related

29 Similar Genes in Plants Master genes called homeotic genes guide formation of specific body parts during development Example: The Apetala1 gene affects formation of petals across many different lineages, so this gene probably evolved in a shared ancestor

30 Developmental Comparisons in Animals Embryos of many vertebrate species develop in similar ways All vertebrates go through a stage in which they have four limb buds, a tail, and a series of somites

31 Fig a, p. 252 Developmental Comparisons in Animals

32 Fig b, p. 252 Developmental Comparisons in Animals

33 Fig c, p. 252 Developmental Comparisons in Animals

34 Fig d, p. 252 Developmental Comparisons in Animals

35 Fig e, p. 252 Developmental Comparisons in Animals

36 Variations in Development Differences are brought about by variations in expression patterns of master genes that govern development Example: The pattern of expression of Hox master genes determines particular zones along the body axis In insects, the Hox gene antennapedia, determines where legs develop on the thorax A vertebrate version of antennapedia, the Hoxc6 gene, causes a vertebra to develop ribs as part of the back

37 Expression of Antennapedia A mutation that causes antennapedia to be expressed in embryonic tissues of a Drosophila’s head (left) causes legs to form there too (right)

38 Fig a, p. 252 Expression of Antennapedia

39 Fig b, p. 252 Expression of Antennapedia

40 Expression of Hox6 Chicks (left) have 7 vertebrae in their back and in their neck; snakes (right) have more than 450 back vertebrae

41 Forever Young Mutations that alter rate of development may allow juvenile traits to persist into adulthood Example: At early stages of development, chimpanzee and human skulls appear quite similar Different parts develop at different rates A human adult skull is proportioned more like the infant chimpanzee skull than the adult chimpanzee skull

42 Proportional Changes During Skull Development

43 Fig , p. 253 proportions in infant adult A B Proportional Changes During Skull Development

44 Fig a, p. 253 Proportional Changes During Skull Development

45 Fig a, p. 253 proportions in infant adult A Proportional Changes During Skull Development

46 Fig b, p. 253 Proportional Changes During Skull Development

47 Fig b, p. 253 proportions in infant adult B Proportional Changes During Skull Development

48 ANIMATION: Mutation and proportional changes To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERECLICK HERE

49 Key Concepts Evidence in Form and Function Different lineages may have similar body parts that reflect descent from a shared ancestor Lineages with common ancestry often develop in similar ways

50 Reflections of a Distant Past (revisited) The K–T boundary layer, an unusual clay that formed 65 million years ago, is rich in iridium, an element rare on Earth’s surface but common in asteroids Scientists found a huge crater, about 65 million years old, off the coast of Mexico’s Yucatán Peninsula – evidence of an asteroid impact that may have caused extinctions


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