Presentation on theme: "Ch. 25 The History of Life on Earth"— Presentation transcript:
1 Ch. 25 The History of Life on Earth Objective:L.O. 1.9 TSIAT: evaluate evidence provided by data from many scientific disciplines that support biological evolution.L.O TSIAT: refine evidence based on data from many scientific disciplines that support biological evolution.L.O TSIAT: design a plan to answer scientific questions regarding how organisms have changed over time using information from morphology, biochemistry and geology.L.O TSIAT: connect scientific evidence from many scientific disciplines to support the modern concept of evolution.L.O TSIAT: construct and/or justify mathematical models, diagrams or simulations that represent processes of biological evolution.L.O TSIAT: pose scientific questions that correctly identify essential properties of shared, core life processes that provide insights into the history of life on Earth.L.O TSIAT: describe specific examples of conserved core biological processes and features shared by all domains or within one domain of life, and how these shared, conserved core processes and features support the concept of common ancestry for all organisms.L.O TSIAT: justify the scientific claim that organisms share many conserved core processes and features that evolved and are widely distributed among organisms today.L.O TSIAT: analyze data related to questions of speciation and extinction throughout the Earth’s history.L.O TSIAT: design a plan for collecting data to investigate the scientific claim that speciation and extinction have occurred throughout the Earth’s history.L.O TSIAT: describe a scientific hypothesis about the origin of life on Earth.L.O TSIAT: evaluate scientific questions based on hypotheses about the origin of life on Earth.L.O TSIAT: describe the reasons for revisions of scientific hypotheses of the origin of life on Earth.L.O TSIAT: evaluate scientific hypotheses about the origin of life on Earth.L.O TSIAT: evaluate the accuracy and legitimacy of data to answer scientific questions about the origin of life on Earth.L.O The student can connect concepts in and across domains to show that timing and coordination of specific events are necessary for normal development in an organism and that these events are regulated by multiple mechanisms.L.O TSIAT: use a graph or diagram to analyze situations or solve problems (quantitatively or qualitatively) that involve timing and coordination of events necessary for normal development in an organism.L.O TSIAT: justify scientific claims with scientific evidence to show that timing and coordination of several events are necessary for normal development in an organism and that these events are regulated by multiple mechanisms.L.O TSIAT: explain how the distribution of ecosystems changes over time by identifying large-scale events that have resulted in these changes in the past.L.O TSIAT: predict consequences of human actions on both local and global ecosystems.
2 OverviewCurrently, the largest fully terrestrial animal in Antarctica is a 5mm long fly.However, fossils on Antarctica show a history of tropical animals, including dinosaurs.An ever changing world give rise to new organisms, but what was the first organic being on Earth?
3 25.1 Conditions on Early Earth Made The Origin of Life Possible Life began in 4 stages:Abiotic synthesis of small organic molecules (amino acids and nitrogen bases)The joining of these small molecules into macromolecules (proteins and nucleic acids)The packaging of these molecules into protocells, droplets with membranes that maintained an internal chemistry different from that of their surroundings.The origin of self-replicating molecules making inheritance possible.
4 Synthesis of Organic Compounds Earth formed ~4.6 b.y.a.Earth was hot.Bombardment by rocks and ice (comets).Early atmosphere likely contained:water vaporchemicals from volcanic eruptions (N2 and its oxides, CO2, methane, ammonia, H2, hydrogen sulfide)Earth cooled forming oceans
5 In 1953, Stanley Miller and Harold Urey conducted lab experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possibleThe first organic compounds may have been synthesized near volcanoes or deep-sea vents due to reducing properties.EXPERIMENT“Atmosphere”ElectrodeCondenserCH4H2NH3Water vaporCooled “rain” containing organic moleculesCold waterSample for chemical analysisH2O “sea”
8 Macromolecules and Protocells Dropping monomers on hot “Earth” produces polymers (amino acids proteins; nucleotides RNA)Vesicles form when lipids are added to water.Formation of lipid bilayerThese vesicles absorb molecules near their surroundings (early proteins and RNA).(a) Self-assemblyTime (minutes)Precursor molecules plusmontmorillonite clayPrecursormolecules onlyan index of vesicle numberRelative turbidity,20 m(b) Reproduction(c) Absorption of RNAVesicleboundary1 m0.20.4402060
9 RNA serves as instructions for protein synthesis as well as acts as enzymes. RNA molecules that were more stable or replicated more quickly would have left the most descendent RNA molecules.Copying errors occurred (mutations) leading to slight differences and thus natural selection.
10 25.2 The Fossil Record Documents The History of Life Fossils are only made in certain conditions, making the fossil record incomplete.However, it can be seen how extinct species could have given rise to current ones (sepciation).DimetrodonStromatolitesFossilizedstromatoliteCoccosteuscuspidatus4.5 cm0.5 m2.5 cmPresentRhomaleosaurusvictorTiktaalikHallucigeniaDickinsoniacostataTappania1 cm1 m100 mya1752003003754005005255656001,5003,500270Figure 25.4
12 Dating FossilsRelative dating: older fossils are lower in the Earth’s strata.Absolute dating (exact age) uses radiometric dating: use of half life’s of radioactive isotopes within the fossil.Accumulating“daughter”isotopeFraction of parentisotope remainingRemaining“parent”Time (half-lives)124816
13 The Origin of New Groups of Organisms Ex: mammals Mammals belong to the group of animals called tetrapodsEvolution of unique mammalian features can be traced through gradual changes over timeOTHERTETRA-PODSTemporalfenestraHinge†Dimetrodon†Very late (non-mammalian)cynodontsMammalsSynapsidsTherapsidsCynodontsReptiles(includingdinosaurs and birds)Key to skull bonesArticularQuadrateSquamosalDentaryHinges(partial view)Early cynodont (260 mya)Very late cynodont (195 mya)Synapsid (300 mya)Therapsid (280 mya)Later cynodont (220 mya)
14 25.3 Key Events in Life’s History Included The Origins of Single-celled and Multicellular Organisms and the Colonization of LandGeologic Time ScaleBoundaries formed by major extinction events3 Eons (Archaean, Proterozoic, Phanerozoic)Phanerozoic (current eon) divided into ErasPaleozoic – age of trilobites to amphibiansMesozoic – age of reptilesCenozoic – age of mammalsOrigin of solarsystem andEarthProkaryotesAtmospheric oxygenArchaean43Proterozoic2AnimalsMulticellulareukaryotesSingle-celledColonizationof landHumansCenozoicMeso-zoicPaleozoic1Bilonsofyearg
15 First Single-Celled Organisms Stromatolites are rocks formed from prokaryotes bind sediment together.Thought to be 1st cellsCells began to photosynthesize, releasing O2 into the atmosphere.Stromatolites
16 heterotrophic eukaryote Ancestral photosynthetic The First EukaryotesFormed 2.1 b.y.a. by the endosymbiont theory.Ancestral mitochondria and chloroplasts were their own type of prokaryotic cells.Mitochondria were up taken by protocells, then chloroplasts.Plasma membraneDNACytoplasmAncestralprokaryoteNuclear envelopeNucleusEndoplasmicreticulumAerobic heterotrophicMitochondrionheterotrophic eukaryotePhotosyntheticPlastidAncestral photosyntheticeukaryote
17 The Origin of Multicellularity Formed ~1.5 b.y.a.First multicellular organism was algae.After “snowball Earth” (long ice age), the Cambrian explosion occurred creating all the phyla that currently exist and 1st predator-prey interactions.SpongesCnidariansEchinodermsChordatesBrachiopodsAnnelidsMolluscsArthropodsEdiacaranCambrianPROTEROZOICPALEOZOICTime (millions of years ago)635605575545515485
18 Colonization of LandFungi, plants, and animals colonized land ~500 m.y.a.Arthropods and tetrapods are the most widespread and diverse land animalsTetrapods evolved from lobe-finned fishes ~365 m.y.a.
19 25.4 The Rise and Fall of Groups of Organisms Reflect Differences in Speciation and Extinction Rates Earth’s crust is broken into plates that are constantly in motion (moving 2cm/yr).This causes changes in habitats and climates on Earth over time (Antarctica used be near the equator). Move, adapt, or die.65.5135251PresentCenozoicNorth AmericaEurasiaAfricaSouthAmericaIndiaAntarcticaMadagascarAustraliaMesozoicPaleozoicMillions of years agoLaurasiaGondwanaPangaeaJuan de FucaPlateNorthAmericanCaribbeanCocos PlatePacificNazcaSouthEurasian PlatePhilippineIndianAfricanAntarcticAustralianScotia PlateArabian
20 (families per million years): Mass ExtinctionsMany species died on Earth around the same time frames.5 mass extinctions have been recorded.b/w Paleozoic and Mesozoic 96% marine life died! (volcano)b/w Mesozoic and Cenozoic killed dinosaurs, etc. (meteor)252015105542488444EraPeriod416EOSD359299C251PTr20065.5JMesozoicNCenozoicQ1003004005006007008009001,0001,100(families per million years):Total extinction rateNumber of families:Paleozoic145NORTH AMERICAYucatánPeninsulaChicxulubcrater
21 Consequences of mass extinctions Loss of current diversity of life on EarthOpens up the way for new life
22 Argyroxiphium sandwicense Adaptive RadiationMany species adapted from 1 due to many new environmental challenges.Global: Extinction of dinosaurs mammal flourishedRegional: Hawaiian Islands newly created and bare for organisms to diversify on.Dubautia laxaDubautia waialealaeKAUA'I5.1millionyearsO'AHU3.7LANAIMOLOKA'I1.3 million yearsMAUIHAWAI'I0.4Argyroxiphium sandwicenseDubautia scabraDubautia linearisN
23 Effects of Developmental Genes 25.5 Major Changes in Body Form Can Result From Changes in The Sequences and Regulation of Developmental GenesEffects of Developmental GenesCurrent organisms are genetically similar to ancestors, but developmental timing makes them physiologically different.Ex: heterochrony between chimps and humans.Ex: Paedomorphosis in salamanders (juvenile anatomy in adults)Chimpanzee infantChimpanzee adultHuman adultHuman fetusChimpanzee fetusGills
24 Changes in Spatial Pattern Hox (homeotic) genes tell cells how to develop according to where it is located on the embryo.
25 Changes in GenesChanges in developmental genes can result in new morphological formsProbably from duplicationsEx: Specific changes in the Ubx gene have been identified that can “turn off” leg developmentHox gene 6Hox gene 7Hox gene 8UbxAbout 400 myaDrosophilaArtemia
26 Changes in Gene Regulation Change in regulation, not sequence of DNA.Ex: threespine sticklebacks in lakes have fewer spines than their marine relativesThe gene sequence remains the same, but the regulation of gene expression is different in the two groups of fishVentral spinesThreespine stickleback(Gasterosteus aculeatus)
27 25.6 Evolution is Not Goal Oriented Evolutionary NoveltiesHuman Eye: a complex organ … how did it evolve?Improve on given structure based on current functionStart simple – photoreceptors that tell light from darkCup photoreptors in round shape.Filter light through a pupilFocus light with a lensProtect eye with corneaPigmented cells(photoreceptors)EpitheliumNerve fibersPigmentedcellsFluid-filled cavityCellularfluid(lens)CorneaOptic nervelayer (retina)OpticnerveLensRetina(a)(b)(d)(c)(e)
28 Evolution is NOT Goal Oriented Organisms don’t think “I need wings” and are then able to make wings over generations.Organisms use what they have that helps them currently.