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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell,

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Presentation on theme: "Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell,"— Presentation transcript:

1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 15 Tracing Evolutionary History

2 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Are Birds Really Dinosaurs with Feathers? For decades, evolutionary biologists debated whether birds evolved from dinosaurs – Fossil Archaeopteryx supported this view – Conflicting view posited birds evolving from a very different reptile group Bird-dinosaur link was supported by cladistics and corroborated in the 1990s by fossil evidence Debate continues on how birds learned to fly

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5 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings MACROEVOLUTION AND EARTH'S HISTORY 15.1 The fossil record chronicles macroevolution Macroevolution is the main event in the evolutionary history of life on Earth – Documented in the fossil record The geologic record is based on the sequence of fossils – Earth's history divided into three eons – Within the most recent eon, eras and periods marked by mass or lesser extinctions

6 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some major events in the history of life – Precambrian period: oldest known fossils- prokaryotes from 3.5 billion years ago – Paleozoic era: lineages that gave rise to modern life forms – Mesozoic era: age of reptiles, including dinosaurs – Cenozoic era: Explosive evolution of mammals, birds, and flowering plants Animation: The Geologic Record Animation: The Geologic Record

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8 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.2 The actual ages of rocks and fossils mark geologic time Radiometric dating can gauge the actual ages of fossils and the rocks in which they are found – Based on the decay time of radioactive isotopes relative to other isotopes Carbon-14 for relatively young fossils Isotopes with longer half-lives for older fossils

9 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.3 Continental drift has played a major role in macroevolution Continental drift is the slow, incessant movement of Earth's crustal plates on the hot mantle World geography changes constantly

10 LE 15-03a Eurasian Plate North American Plate Pacific Plate Nazca Plate African Plate South American Plate Arabian Plate Indian Plate Antarctic Plate Split developing Australian Plate Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events)

11 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Continental movements have greatly influenced the distribution of organisms around the world – Formation of Pangaea 250 million years ago altered habitats and triggered extinctions – Breakup of Pangea beginning 180 million years ago created a number of separate evolutionary arenas Explains the geographical distribution of diverse life forms – Examples: marsupials, lungfishes

12 LE 15-03b North America Eurasia India Africa South America Australia Antarctica Cenozoic Mesozoic Laurasia Gondwana Pangaea Paleozoic Millions of years ago 251

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14 LE 15-03d North America South America Africa Living lungfishes Fossilized lungfishes = = Europe Asia Australia

15 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CONNECTION 15.4 Tectonic trauma imperils local life Plate tectonics are the forces involved in movements of Earth's crustal plates – The geologic processes that result include volcanoes and earthquakes Can create devastation or opportunities for organisms – The boundaries of plates are hot spots of such geologic activity Video: Galápagos Islands Overview Video: Galápagos Islands Overview

16 LE 15-04a San Francisco North American Plate Santa Cruz Pacific Plate Los Angeles California San Andreas Fault

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18 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.5 Mass extinctions were followed by diversification of life-forms Extinctions occur all the time, but extinction rates have not been steady Over the last 600 million years, at least six periods of mass extinctions have occurred, including – Permian extinction (250 million years ago); claimed 96% of aquatic life – Cretaceous extinction (65 million years ago); eliminated dinosaurs

19 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cause of mass extinctions is unclear – Permian extinction occurred at a time of enormous volcanic explosions – Cretaceous extinction may have been caused by an asteroid Mass extinctions have been followed by an explosive increase in diversity – Provide surviving organisms with new environmental opportunities – Example: rise of mammals after extinction of dinosaurs

20 LE North America Chicxulub crater Yucatan Peninsula Yucatan Peninsula

21 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Video: Lava Flow Video: Lava Flow Video: Volcanic Eruption Video: Volcanic Eruption

22 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PHYLOGENY AND SYSTEMATICS 15.6 Phylogenies are based on homologies in fossils and living organisms Phylogeny is the evolutionary history of a group of organisms – Traced partly from the fossil record – Also inferred from morphological and molecular homologies among living organisms May reveal common ancestry

23 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Not all likenesses are inherited from a common ancestor – Analogy: similarity due to convergent evolution Species from different evolutionary branches may come to resemble each other if they live in similar environments Systematics is the analytical study of diversity and phylogeny

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25 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.7 Systematics connects classification with evolutionary history Systematics includes binomial designation of species and hierarchical classification A binomial gives each species a two-part name – Genus (a group of related species) – Species within the genus Genera are grouped into progressively more inclusive categories (taxa) – Family, order, class, phylum, kingdom, domain

26 LE 15-07a Species Genus Family Order Class Mammalia Carnivora Felidae Felis catus Phylum Kingdom Domain Chordata Animalia Eukarya

27 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A phylogenetic tree is a hypothetical hierarchy of evolutionary relationships

28 LE 15-07b (domestic cat) Felis catus Mephitis mephitis (striped skunk) Lutra lutra Canis familiaris (domestic dog)(European otter) Canis lupus (wolf) Species FelisGenus Family OrderCarnivora Mustelidae Felidae Mephitis Lutra Canis Canidae

29 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.8 Cladograms are diagrams based on shared characters among species Cladistics is concerned with the order of branching in phylogenetic lineages – Each branch (clade) on a cladogram represents an ancestral species and all its descendants – Each clade consists of taxa that are monophyletic (from a "single tribe")

30 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings All the taxa on a clade share one or more homologous features – Shared derived characters: New traits unique to each lineage – Shared primitive characters: Traits present in the ancestral groups Comparison of ingroup and outgroup is important in cladistics – Ingroup: Group of taxa being analyzed – Outgroup: Closely related to the ingroup but not a member of it

31 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Parsimony seeks the simplest explanation of observed data – The simplest (most parsimonious) hypothesis of relationships creates the most likely phylogenetic tree

32 LE 15-08b LizardsSnakes Common reptilian ancestor BirdsCrocodiles

33 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 15.9 Molecular biology is a powerful tool in systematics Molecular systematics uses DNA and RNA to compare relatedness – The closer the nucleic acid sequences between two organisms, the more likely they are to share a common ancestor – Molecular trees cover long and short times based on the different rates at which different genes evolve Humans are more closely related to fungi than to plants

34 LE 15-09a Brown bear Polar bear Asiatic black bear American black bear Sun bear Sloth bear Spectacled bear Giant panda Lesser panda Raccoon Pleistocene Pliocene Ursidae Procyonidae Common ancestral carnivorans Miocene Oligocene Millions of years ago

35 LE 15-09b Student Mushroom Tulip Common ancestor

36 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Computer DNA analysis can show exactly how many bases are alike in homologous regions Some regions of DNA change at a rate consistent enough to serve as molecular clocks to date evolutionary events Comparison of entire genomes reveals interesting homologies – Humans and chimpanzees are 99% identical

37 LE 15-09c HumanChimpanzeeGorillaOrangutan Common ancestor

38 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Arranging life into kingdoms is a work in progress Five-kingdom system – All prokaryotes are in kingdom Monera – Eukaryotes are grouped into four kingdoms: Protista, Plantae, Fungi, Animalia – Molecular studies have found flaws in this system

39 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The domain system – Prokaryotes are in two domains: Bacteria and Archaea – All eukaryotes are in domain Eukarya All classification systems are human constructions, not facts of nature – Will always be refined by new data Animation: Classification Schemes Animation: Classification Schemes

40 LE 15-10a MoneraProtistaPlantae Fungi Animalia Earliest organisms Prokaryotes Eukaryotes

41 LE 15-un311-1 Birds Mammals Lizards


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