Presentation on theme: "Evolution: Evidence and Theory"— Presentation transcript:
1Evolution: Evidence and Theory Chapter 15Evolution: Evidence and Theory
2Evidence for Evolution – The Fossil Record copyright cmassengale
3Fossil Evidence FOSSIL…. a trace of a long-dead organism usually left in sedimentary rock andcan be seen in different layers (strata)examples: trace (footprints, scat), mold (imprint), cast (rocklike model), replacement, petrified, amber, original material (bones, shells, seeds, feathers)
4The difference between a mold and a cast Mold – an imprint in rock Cast – rocklike model of the organism
5Fossil RecordThe fossil record traces history of life and allows us to study history of particular organismsThrough radioactive dating, geologists estimate the age of the earth at about 4.6 billion years
6Fossil RecordFossils are at least 10,000 years old and include skeletons, shells, seeds, insects trapped in amber, imprints of organisms, organisms frozen in ice (wooly mammoth), or trapped in tar pits (saber-toothed tiger)Transitional forms reveal links between groups (Example: Therapsids were mammal-like reptiles and Pterosaurs were bird like reptiles)
7ScientistsRobert Hooke (1668) One of the first scientists to study fossils, principally petrified wood, with the aid of a microscope. He hypothesized that living organisms had somehow turned to rock.
8Scientist Nicolaus Steno (1669) Proposed the law of superposition which states that successive layers of rock or soil were deposited on top of one another by wind or water.Relative age of fossils
9SuperpositionThe layer of strata on the bottom is the oldest and the layer on the top is the youngest.Using this law scientists can estimate the relative age of a fossil by comparing a fossil to others found in the same layer.
10Dating Fossils The 2 most common ways are… Relative Dating: based on law of superposition (lower fossils are older)Radiometric Dating: based on half-life (uses the decay of radioactive isotopes to measure the age – half life)
11Succession of FormsExtinction occurs when previous adaptations are no longer suitable to a changed environmentThe fossil record indicates that there were several mass extinctions.Some of these life-forms were unlike any organism alive today.
13What is an ERa e·ra/ˈi(ə)rə/ Noun: A long and distinct period of history with a particular feature or characteristic.A system of chronology dating from a particular noteworthy event.
14Precambrian eraThe Precambrian Era is Earth's first era of time. It began with the creation of the Earth around 4.6 billion years ago and lasted until 570 million years ago. The Precambrian saw many drastic changes during this time. The five major events of the Precambrian are:1. The formation of the Sun and light.2. The creation of the Earth.3. The creation of the atmosphere through volcanic out-gassing.4. The creation of the oceans. After rainfall, the Earth's surface was cooled down and the rainwater collected into low areas which formed oceans and seas. The ocean became stable around 1 bya when no more salt from rocks could be dissolved into the water.5. The creation of life (Prokaryotes, then eukaryotes). This actual process remains open to debate as to how it all took place.
15Paleozoic Era The Paleozoic era began when the Precambrian era ended. There was an explosion of life marking the beginning of the Paleozoic.Paleozoic means ancient life.There are six periods within the Paleozoic Era. These periods include the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian.
16Cambrian 570 mya to 500 myaThe Cambrian Period lasted for 70 million years. The Cambrian is the first period of the Paleozoic Era.The Cambrian is quite different from the Precambrian in that the animals could see, think, and they had exoskeletons.All life existed in the oceans at this time because the ozone layer was not developed to withstand ultraviolet rays from the Sun. The most advanced animal of this period was the trilobite. The Cambrian is known as "the age of the trilobites."
17Ordovician 500 mya to 440 myaThe Ordovician Period existed for 60 million years.The Ordovician was shorter than the Cambrian period.All life still existed in the ocean because of the lack of proper ozone levels. The trilobite became larger and smarter during this time. The major life form of this time period was the shell fish. The Ordovician is called "the age of the shell fish."
18Silurian 440 mya to 400 myaThe Silurian Period lasted for 40 million years.The Silurian marks the first time that life existed on land.These life forms were simple plants such as Psilophyton, a vine-type plant. Plants of this period did not possess leaves or flowers. The Silurian is called "the age of the first life on land." Ozone levels have reached the required thickness to protect life on land from now on.
19Devonian 400 mya to 350 myaThe Devonian Period lasted for 50 million years. The Devonian is called "the age of the fishes."Two types of fish developed during this time period: jawless and jawed fish. The jawless fish were armor plated with bones and used suction to feed through their mouths. Some jawed fish developed lungs, and the first animal life walked upon the land at this time. Sharks also made their début at this time.
20Carboniferous 350 mya to 280 mya The Carboniferous Period, also called the Mississippian and Pennsylvanian Periods, lasted for 70 million years.The Carboniferous is often called "the age of swamps and coal." During this time period much of the land was covered by swamps and seas. The climate was extremely warm during this period. Giant insects and plants dominated this period. Much of the coal supplies world-wide originated from this period.
21Permian 280 mya to 225 myaThe Permian Period existed for 55 million years. The Permian period saw the rise of dinosaurs and mammals.It is often called "the age of mass extinction" or "the age of amphibians." Giant amphibians ruled the land during this period. This period marks the end of the Paleozoic Era when an asteroid around 10 miles in diameter struck the North American Continent at Hudson Bay, Canada. The asteroid strike was so devastating that 98% of life on Earth was wiped out! This destruction was caused when dust from the impact circled the globe via the jet stream and blocked out the Sun for many years, freezing most life on Earth.
22Mesozoic Era The Mesozoic Era existed from 225 mya to 65 mya. The Mesozoic Era is divided into three periods of time. These periods are: the Triassic, Jurassic and Cretaceous.
23Triassic 225 mya to 195 myaThe Triassic Period lasted 30 million years. The Triassic is called "the age of dinosaurs."Shortly after the asteroid strike, the dinosaurs and mammals were left on Earth.Dinosaurs, being reptiles, had advantages over mammals in that they were "ready to go" when born, they could reproduce higher numbers of young and they were larger. This helped dinosaurs take control of the Earth during this period.
24Jurassic 195 mya to 135 myaThe Jurassic Period lasted 60 million years. The Jurassic saw many changes in dinosaurs during this period. The dinosaurs were mainly herbivores in that they ate plants. The dinosaurs of this period grew to 140 feet long in some cases! The Jurassic is often marked as "the first time period when life existed in the sky." The first bird-like dinosaur was called the Archaeopteryx.
25Cretaceous 135 mya to 65 myaThe Cretaceous Period lasted for 70 million years. The Cretaceous is known as "the age of the carnivores."This time period saw the rise of meat eaters such as T-Rex, which required 2 tons of meat a day to survive. The Cretaceous time period saw the first flowers on plants.The Cretaceous is also marked by a mass extinction event that ended the Mesozoic Era. An asteroid around a few miles in diameter struck the Earth at the Yutan peninsula in Mexico. This created a global dust cloud around the world and wiped out 65% of all life on Earth. This ended the age of the dinosaurs.
26Dinosaurs were extinguished by five reasons: 1. They grew too big to support their feeding habits.2. They suffered from diseases such as cancer.3. Their climate changed as the continents moved to northern or far southern latitudes.4. Mammals, such as rats, destroyed their eggs faster than they could produce them.5. The asteroid strike was the final blow.There is a theory out there that suggests that dinosaurs became birds, and there is some evidence to support that. Next time you see a bird, maybe T-Rex is looking back at you!
27Cenozoic era The Cenozoic Era began when the Mesozoic ended 65 mya. The Cenozoic gave witness to the rise of mammals. The Cenozoic Era is called "the era of mammals."The Cenozoic Era is divided into two periods and six epochs. The two periods are the Tertiary and the Quaternary. The seven epochs include: the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and Holocene.The Cenozoic Era is marked by the rise and diversification of mammals as they gained dominance over the Earth.The era is also marked by repeated ice ages which altered and modified not just the land, but also life itself.
28Tertiary 65 mya to 2 myaThe Tertiary lasted 63 million years. This period is called "the age of the rise of mammals."Mankind also appeared for the first time in the fossil record around 5 million years ago late in the Tertiary Period.The Tertiary Period includes the Paleocene, Eocene, Oligocene, Miocene and Pliocene epochs.
29The Seven Epochs are:Tertiary PeriodPaleocene (65 mya to 55 mya - Rise of Mammals)Eocene (55 mya to 38 mya - Saber Tooth Cats, Primitive Horses)Oligocene (38 mya to 25 mya - First Primates)Miocene (25 mya to 5 mya - Apes)Pliocene (5 mya to 2 mya - First Man)
30Quaternary PeriodPleistocene (2 mya to 10,000 years ago - The Rise of Man)Holocene (10,000 years ago to present - Modern Man)
31The Seven Epochs represent changes in climate such as ice ages and the rise of different species of mammals.
32Quaternary 2 mya to present The Quaternary has lasted 2 million years so far. We are in the Quaternary period.This period is known as "the age of man," since mankind has dominated the Earth since the beginning of this period.The Quaternary contains the Pleistocene and Holocene epochs.
33Biogeographical Evidence: Biogeography is the study of the geographic distribution of life forms on earthPhysical factors, such as the location of continents, determine where a population can spreadExample: Placental mammals arose after Australia separated from the other continents, so only marsupials diversified in Australia
34Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionJean-Baptiste Lamarck, 1809One Of First Scientists To Understand That Change Occurs Over TimeStated that Changes Are Adaptations To Environment acquired in an organism’s lifetimeSaid acquired changes were passed to offspring
35Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionIdea called Law of Use and DisuseIf a body part were used, it got strongerIf body part NOT used, it deteriorated
36Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionInheritance of Acquired CharacteristicsProposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their LifetimeThese Traits Could Then Be Passed On To Their OffspringOver Time This Led To New Species
37Geographic Distribution of Living Species Different Animals On Different Continents But Similar Adaptations To Shared Environments
38Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionUse & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using ThemBlacksmiths & Their Sons (muscular arms)Giraffe’s Necks Longer from stretching)
40Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionInheritance Of Acquired TraitsTraits Acquired During Ones Lifetime Would Be Passed To OffspringClipped ears of dogs could be passed to offspring!
41Lamarck’s Theory of Evolution copyright cmassengaleLamarck’s Theory of EvolutionTendency Toward PerfectionOrganisms Are Continually Changing and Acquiring Features That Help Them Live More Successfully In Their EnvironmentExample: Bird Ancestors Desired To Fly So They Tried Until Wings Developed
42Genes Are NOT Changed By Activities In Life copyright cmassengaleLamarck’s MistakesLamarck Did NOT Know how traits were inherited (Traits are passed through genes)Genes Are NOT Changed By Activities In LifeChange Through Mutation Occurs Before An Organism Is Born
46Contributor’s to Darwin’s thinking included: Charles Lyell –uniformatarianismGeorges Cuvier – species extinction (Catastrophism)Thomas Malthus – struggle for existence (resources)
47Contributor’s to Darwin’s thinking included: James Hutton - GradualismJohn Baptiste Lamarck – Inheritance of acquired Characteristics and Law of Use and DisuseAlfred Russel Wallace – organisms evolved from common ancestors
48Charles Lyell Proposed theory of Uniformitarianism Geological processes at uniform rates building & wearing down Earth’s crustProposed that the Earth was millions of years instead of a few thousand years old
50The Galapagos Islands Very Different Climates Small Group of Islands 1000 km West of South AmericaVery Different ClimatesAnimals On Islands UniqueTortoisesIguanasFinches
51The Galapagos IslandsFinches on the islands resembled a mainland finchMore types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…)Finches had different types of beaks adapted to their type of food gathering
53Publication of “On The Origin of Species” Upon His Return To England, Darwin Developed His Observations Into The Theory of EvolutionBut He Did Not Publish For 25 Years –Why?
54Publication of “On The Origin of Species” Darwin Knew That His Theory Would Be Extremely Controversial And Would Be AttackedHis Theory Challenged Established Religious & Scientific Beliefs, Particularly About The Creation Of Man
55Publication of “On The Origin of Species” He Refused To Publish Until He Received An Essay From Alfred WallaceFellow NaturalistIndependently Developed The Same TheoryAfter 25 Years, Someone Else Had Come To The Same Conclusions From Their Observations Of Nature
56Cannot Be Seen Directly Darwin’s theoriesCannot Be Seen DirectlyIt Can Only Be Observed As Changes In A Population Over Many Successive GenerationsRadiationFossil Record
57Descent With Modification Takes Place Over Long Periods of TimeNatural Selection Can Be Observed As Changes InBody StructuresEcological NichesHabitats
58Descent With Modification Species Today Look Different From Their AncestorsEach Living Species HasDescendedWith ChangesFrom Other SpeciesOver Time
60Descent With Modification ImpliesAll Living Organisms Are RelatedSingle Tree of LifeDNA, Body Structures, Energy SourcesCommon DescentAll Species, Living & Extinct, Were Derived From Common Ancestors
61Major Problem in Darwin’s Theory No mechanism to explain natural selectionHow could favorable variations be transmitted to later generations?With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was found.
62Ideas That Shaped Darwin’s Thinking Thomas MalthusIdeas That Shaped Darwin’s Thinking
63Population GrowthThomas Malthus, 1798EconomistObserved Babies Being Born Faster Than People Were DyingPopulation size limited by resources such as the Food Supply
64The Struggle for Existence Malthus’ Influence:High Birth Rates & Limited Resources Would Force Life & Death CompetitionEach Species Struggles For:FoodLiving SpaceMates
65Population GrowthMalthus Reasoned That If The Human Population Continued To Grow Unchecked, Sooner or Later There Would Be Insufficient Living Space & Food For EveryoneDeath Rate Will Increase To Balance Population size & Food Supply
66Population GrowthDarwin Realized Malthus’s Principles Were Visible In NaturePlants & Animals Produce Far More Offspring Than Can Be SupportedMost DieIf They Didn’t – Earth Would Be Overrun
67Natural Selection Driving force for evolution During the struggle for resources, strongest survive & reproduceIdea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable.
68Natural Variation and Artificial Selection Abandoned The Idea That Species Were Perfect & UnchangingObserved Significant Variation in All Species ObservedObserved Farmers Use Variation To Improve Crops & LivestockCalled Selective Breeding
69Natural Variation and Artificial Selection Differences Among Individuals Of A SpeciesArtificial SelectionSelective Breeding To Enhance Desired Traits Among Stock or Crops
70Natural Variation and Artificial Selection Key Concept:In Artificial Selection, Nature Provided The Variation Among Different Organisms, And Humans Selected Those Variations That They Found Useful
72DefinitionEvolution is the slow , gradual change in a population of organisms over time
73Darwin’s Observations Left unchecked, the number of organisms of each species will increase exponentially, generation to generationIn nature, populations tend to remain stable in sizeEnvironmental resources are limited
74Darwin’s ConclusionProduction of more individuals than can be supported by the environment leads to a struggle for existence among individualsOnly a fraction of offspring survive each generationSurvival of the Fittest
75Darwin’s Theory of Evolution The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection)New species evolve
77Evolution By Natural Selection Concepts The Struggle for Existence (compete for food, mates, space, water, etc.)Survival of the Fittest (strongest able to survive and reproduce)Descent with Modification (new species arise from common ancestor replacing less fit species)
78Survival of the Fittest FitnessAbility of an Individual To Survive & ReproduceAdaptationInherited Characteristic That Increases an Organisms Chance for Survival
79Survival of the Fittest Adaptations Can Be:PhysicalSpeed, Camouflage, Claws, Quills, etc.BehavioralSolitary, Herds, Packs, Activity, etc.
80Survival of the Fittest Fitness Is Central To The Process Of EvolutionIndividuals With Low FitnessDieProduce Few OffspringSurvival of the FittestAKA Natural Selection
81Survival of the Fittest Key ConceptOver Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment
82Theory of Evolution Today Supporting EvidenceTheory of Evolution Today
83Homologous Structures - structures having different mature forms but develop from a common ancestor Example: forelimbs of human, cat, whale and bat
84Analogous Structures – structures having similar functions but develop from different ancestors Example: wings of insect, pterodactyl, bird and bat
85Vestigial Structures/Vestigial Organs - structures that serve no useful function in an organism Example: appendix in man, dew claw on dogs
86Similarities In Embryonic Development Evidence for Evolution - Comparative EmbryologySimilarities In Embryonic Development
87similarities in the biochemistry of species indicates common ancestry Biochemical Evidencesimilarities in the biochemistry ofspecies indicates common ancestryalmost all living organisms have the same molecules: DNA, RNA, ATP, enzymes, etc.amino acid sequences are similargenetic code = A T C G (in ALL living things)