Evolution natural selection_and_speciation most current file
“Evolve” Means to Change Over Time The notion that life on Earth has changed over time is quite old To be considered science, this notion requires a great deal of evidence
The Development of Evolutionary TheoryNaturalists have always wondered at thediversity of living things………Great varieties in shape, size, and ecological roleEstimated 3 million to 20 million different livingspeciesMuch of the natural world’s biodiversity has vanishedthrough extinction99% of all species that ever lived are now extinctPermian-Triassic Mass ExtinctionWhat Killed the Dinosaurs?
Development of Evolutionary TheoryWhat could cause such great diversity, and why have so many species died out?Charles Darwin offered an explanation based on careful observationsWho was Charles Darwin?
Development of Evolutionary TheoryDarwin Concluded: Physical traits and behaviors enable organisms to survive and reproduce (called Fitness ) Fitness results from adaptations Structural (body structures) Behavioral (protection, predation, mating, etc.) Functional (chemicals produced by the organism that perform special functions)
Development of Evolutionary Theory Darwin reasoned that adaptations result from natural selection and result in evolution Evolution is the process by which living things change and diversify over time
Development of Evolutionary Theory These ideas were widely challenged until a tremendous amount of evidence was gathered to support evolution! Now…The Theory of Evolution is the Cornerstone of Biology Explore the Evolution Revolution
Charles Darwin Studied Medicine and Theology Excelled in Geology and Biology In 1831 Darwin joined the H.M.S. Beagle on a trip around the world to make maps He was the ship’s naturalist Darwin’s Diary
Darwin Pieces Together the PuzzleDarwin traveled South America & GalapagosIslandsCollecting fossils and other specimensMaking detailed observations of animal behaviorMaking detailed drawings of the organisms he encountered
The Voyage of the Beagle: Ports of CallNoted that populations oforganisms were slightlydifferent from place toplaceEach group was modifiedto their specificenvironment
Darwin Pieces Together the Puzzle Author of “Principles ofCharles Lyell Geology” This book helped Darwin realize that the earth is old and changes slowly over time.
Darwin Pieces Together the Puzzle Thomas MalthusMalthus wrote “Essay onthe Principles of Population”Populations will always grow largerthan the food supply, creating hunger,disease and struggle/competition.Some people live, others die. 18th Century Economist
Darwin Pieces Together the PuzzleDarwin coined the term Artificial Selection- the process of modification of a species throughhuman actions which encourage the breeding ofcertain traits over others. http://www.esp.org/books/darwin/variation/facsimile/title3.html
Darwin Pieces Together the PuzzleWhat Darwin Learned from Artificial Selection When chosen organisms are mated, desired characteristics are formed (Darwin didn’t know about DNA) Individuals in the wild who possess characteristics that make it more likely for them to reproduce will pass along these characteristics to their offspring. “Desirable" characteristics, in the wild, would be those which enhance survivability, NOT those which specifically satisfy human needs. Nature does the selecting.
Darwin Pieces Together the PuzzleLamarck’s View of Evolution Stated that acquired characteristics can be passed on to offspring.
Darwin Pieces Together the PuzzleDarwin’s View of Evolution Those giraffes with longer necks got more food and were better able to survive to reproduce, passing on the long-neck genes to their offspring. Over time, giraffes evolved longer necks.
4 Key Ideas of Natural Selection “Of course, long before you mature, most of you will be eaten.”
Natural SelectionEvolution Through Natural Selection Variation (genetic) is present in the population and this variation is inherited (genetically passed to offspring). (Praying Mantis Camouflage) Living things Overproduce Competition for Limited Resources Survival of the “Fittest” Reluctantly published On the Origin of Species in 1859 Video
Natural Selection4 Main Points of Natural Selection Variation (genetic) is present in the population and this variation is inherited (genetically passed to offspring). Living things Overproduce Competition for Limited Resources Survival of the “Fittest” Video
The Fittest SurviveFitness Defined Organisms who better survive to produce larger numbers of offspring are considered more fit than others who do not.
Darwin Today…Natural Selection in action… causes a frequency of certain alleles in a population to increase or decrease over time!
Click the Link Below to Access the Cartoon http://evolution.berkeley.edu/evolibrary/artic Read the cartoon carefully and answer the discussion questions on a separate sheet of paper.
Speciation Natural Selection modifies populations. Some evolutionary changes are so great that some organisms can no longer interbreed with the original population A new species results Species An interbreeding population of organisms that can produce healthy, fertile offspring
Reproductive Barriers and Speciation Prezygotic: gametes never meet and fuse Geographic isolation (allopatric speciation) Ecological isolation Behavioral isolation (lacewing songs) Mechanical isolation Seasonal isolation Postzygotic: genetic differences manifest Hybrid inviability Hybrid sterility (tigons and ligers)
Geographic Isolation2 populationsseparated bygeographic barriers(rivers, mountains,bodies of water) Abert Squirrel vs. Kaibab Squirrel
Temporal Isolation (Seasonal)Species reproduce atdifferent times
Mechanical IsolationMating/Pollination is often impossiblebetween different animal/plant speciesbecause of the incompatible shape andsize of the reproductive structures.Size Does Matter!Example – Black and White Sage Plants
Black sage and white sage plantsinvite different pollinatorsWhite sage flowers have large landing platforms for large pollinators causing thelarge pollinators to brush against the stamens, but the small ones usually don’t.Black sage flowers have small landing platform for small pollinators. Therefore,the small pollinators cannot spread pollen to the white sage flowers thereforecross pollination is no longer possible.
Ecological Isolation Two populations live in different habitats and mating occurs in those habitats, thus their own gene pool.Land Iguana Marine Iguana
After Mating Genetic Differences OccurHybrid sterility (tigons and ligers) (Horse and a donkey = mule – sterile)
Patterns in Evolution Adaptive Radiation (Divergence) Development of numerous new species from a common ancestor in diverse environments Darwin’s Finches (Origin of Species Activity)
TaxonomyClassification and naming of organisms7 Taxonomic Groupings from most inclusive to mostspecific: • Kingdom “Kings play chess on fine green silk” • Phylum • Class • Order • Family • Genus • Species
Linnean TaxonomyCarolus Linnaeus (1707-1778)Binomial nomenclature (2 name naming)Genus and species to make the scientificnameProvides a common name that can beused by all biologists regardless of theirnative language.
Linnean Taxonomy Example: human vs. chimpanzee • Kingdom animalia animalia • Phylum chordata chordata • Class mammalia mammalia • Order primata primata • Family hominidae hominidae • Genus homo pan • Species sapiens troglodytes• Homo sapiens and Pan troglodytes• Classification activity
Scientists from many disciplines includingbiology, chemistry, physics, geology, andpaleontology have contributed to the casefor evolution! The Origin of Life Geology The Fossil Record Comparative Embryology Comparative Biochemistry Comparative Anatomy Isn’t Evolution Just a Theory?
The Origin of Life Origin of the Universe Big Bang
Early Earth Evolution Starts Up: Chemical Evolution Heterotroph Hypothesis: Molecules of life arose from inorganic building blocks
The Miller-Urey Experiment Studied Molecules Present at Time of Early Earth Methane, Ammonia, Carbon Dioxide, Water Vapor Mixed Molecules in Reaction Chamber Sparked with Electricity to Simulate Lightning Exposed Mixture to UV Radiation to Simulate Cosmic Rays Produced Basic Amino Acids and Organic Molecules
Biological Evolution RNA as a information molecule and catalyst Endosymbiotic Theory Mitochondria and chloroplasts were originally free living prokaryotic cells Both have own DNA and ribosomes Joined together to cooperate
GeologyThe Study of the Earth and RocksEarly Ideas About Earth: People believed Earth was only a few thousand years old People believed that rocks and geological features were shaped by catastrophic events and rarely changed
GeologyThese ideas refute the idea that the Earth isonly a few thousand years oldProvides long time necessary for evolutionBacked up by radiometric dating The Earth is approximately 4.6 Billion Years Old 4,600,000,000 years is a long time!
The Fossil Record Fossils are the preserved remains of ancient organisms Provide information about past organisms Shows that many diverse organisms lived at different times in Earth’s History
Preserved remains or traces of ancient organisms Examples:
The Fossil RecordProvide a record of past speciesImportant source of information fordetermining ancestry and patterns of evolution Fossil Archaeopteryx
What does the fossil record tell us? •What past life looked like •What past habitats were like and changes that have occurred •That diverse organisms lived on earth at different times •New species evolved •Some species became extinct •Earliest life forms were aquatic •Earliest life forms were simple in structurehttp://www.pbs.org/wgbh/evolution/library/04/3/quicktime/l_043_01.html
The Fossil Record Taphonomy: The Formation of Fossils Fossils form in sedimentary rock Dead organisms covered by sand and silt Sediments are passed into bone by pressure from above (fossils form in sedimentary rock) Video
Determining the Age of Fossils Relative Dating: Technique used by scientists to determine the age of fossils relative to fossils in other layers of rock Different layers represent different geologic periods Older fossils found in lower layers, newer fossils found in upper layers Cannot determine the actual age of the fossil!
Determining the Age of Fossils Radioactive Dating: Process by which traces of radioactive elements are analyzed to calculate the actual age of a fossil Many radioactive elements can be used as geologic clocks. Each radioactive element decays at its own nearly constant rate. Once this rate is known, geologists can estimate the length of time over which decay has been occurring by measuring the amount of radioactive parent element and the amount of stable daughter elements Video
Radioactive/Radiometric DatingHow it Works:- radioactive elements (uranium, Carbon14) break down/decay a specific rates = half life- these rates are nearly constant - the amount of radioactive decay thathas taken place in a rock/fossil determinesits age
Scientist Measure the Age of the EarthRadiometric Dating: way of estimating the age of the Earth! http://www.pbs.org/wgbh/evolution/library/03/3/quicktime/l_033_01.html
5,700 year is C14 half-lifeCarbon-14 Dating- Determines the age offossils of a biologicalorigin up to approx.50,000 years old.- used in dating thingssuch as bone, cloth,wood, plant fibers, etc.
Half-life of carbon-14 is 5730 years 22,920 11,460 28,650 17,190
Radiometric Dating Radioactive Stable Half life Parent Daughter 1.25 billion Potassium 40 Argon 40 yrs Strontium 48.8 billion Rubidium 87 87 yrs 14 billion Thorium 232 Lead 208 years 704 million Uranium 235 Lead 207 years 4.47 billion Uranium 238 Lead 206 years Carbon 14 Nitrogen 14 5730 years
The Geologic Time Scale Based on fossil and geologic evidence A record of the Earth’s past Divided into Era, Period, and Epoch Shows that life on Earth followed geologic change on Earth Deep Time Activity Interactive Time Scale
Comparative Embryology Embryos are organisms at early stages of development
Comparative EmbryologyAll vertebrate embryos,including humans, sharefeatures Eye spot • (Evolution of the Human Eye) Gill pouches NotochordShows similar geneticancestryVideo
Comparative BiochemistryAll life is based on organic chemistry Carbon based compoundsAll life uses same molecule as blueprint DNASimilar chemical processes Bacteria, algae, and plants all do photosynthesisSimilar organisms have similar genetic code Humans and chimpanzees share nearly identical genes (98.4% identical gene sequences) Video
Anatomy and Comparative Anatomy Vestigial Organs Organs inherited but not used by modern organisms Present but greatly reduced in modern organisms Hip bone in python Appendix in human Tail bone (cocyx) in human
Anatomy: Homologous Structures Similar parts of different organisms, often quite dissimilar in purpose, that developed from the same ancestral body parts (Video) Divergent evolution
Anatomy: Analogous Structures Similar in purpose, but not inherited from a recent common ancestor Environment selected for trait Wings of birds and insects Convergent evolution
Summary There is overwhelming evidence to support the Theory of Evolution Evidence comes from disciplines as varied as biology, geology, chemistry, physics, astronomy, and paleontology Evolution has produced the great beauty and diversity of life on Earth over the last 4 billion years
Explore Human EvolutionView the Becoming Human broadbanddocumentary As you view each segment, visit the related exhibits to further explore this topicGo to the Learning Center and select the“Calculating Cousins” activityGo to the Learning Center and select the“Chromosome Connection” activityGo to the Learning Center and select the“Building Bodies” activity
The Order Primate Characteristics of Primates Strong hands and opposable thumbs Free-moving shoulder joint Forward facing eyes and stereoscopic vision Intelligence/larger brain Social complexity
What Characteristics do Humans Have? All of those of primates, plus Upright posture and bipedal Use of tools and technology Advanced intelligence Complex communication and speech
The Steps to Human EvolutionTerrestrializationBipedal (Walking on all two’s)Increased Brain SizeCivilizationTake a look at the Human family tree
The Hominid FamilyEach year new fossils are found to addto the Hominid family treeMost fossils of early humans are foundin Africa and lower AsiaMost well understood members includegenus Australopithecus (extinct) andgenus HomoSolve the Riddle of the Bones
Genus Australopithecus First human ancestor to live on the ground and walk on two legs As evidenced by the Laetoli footprints Ape-like jaw Small brain Short stature Found only in South and East Africa
The Australopithecines A. anamesis 4 MYA A. afarensis 3.2 MYA (Finding “Lucy”) A. africanus 2.5 MYA A. robustus 2 MYA A. boisei 2 MYA
Genus Homo More modern hominids that exhibited major evolutionary steps Increased brain size Use of tools Use of fire Use of shelter Religion Language and civilization
Homo habilis “The Tool Man” Approx. 2.5 MYA Brain ½ size of modern human First to make and use stone tools and weapons
Homo erectus “The Upright Man” Direct ancestor of modern humans Widespread in Africa and Asia by 1 MYA Evidence of use of shelter and fire
Homo sapiens “The Wise Man” Most likely evolved from H. erectus as early as 400,000 years ago Greatly increased brain size Consisted of 2 groups Neanderthal Cro-Magnon/modern H. sapiens
Neanderthals Found in Neander Valley in Germany Fossils found throughout Europe, Middle East, and Asia from 150,000-30,000 years ago Large bodies and brains Evidenced painting, religion, complex social structure “Cave man”
Cro Magnons and Fully Modern Humans First early modern H. sapiens appear about 130,000 years ago Thinner bones, smaller jaws, higher skull with little or no brow ridge, and larger brains Cave art shows complex religion and culture Lived alongside Neanderthal for several thousand years, but eventually out-competed them