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This 7 page Class Notes was uploaded by Nicole on Friday September 4, 2015. The Class Notes belongs to BIO200 at University at Buffalo taught by Dr. Lindqvist in Summer 2015. Since its upload, it has received 224 views. For similar materials see Evolutionary Biology in Biology at University at Buffalo.
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DIOLUU LBCUH39B N OteS week 1 Lecture 2a History of Earth Rapid evolution 90 of dog breeds did not exist only 120 years ago Physical changes to Earth in uenced evolution of life Cosmic Calendar created by Carl Sagan One month 1 billion years One day 40 million years Begins with formation of Universe at Ianuary 1St Formation of our solar system did not occur until August 31St First humans did not appear until December 31St at midnight Formation of Earth Rotating cloud of dust rocks amp gas called protoplanetary disk Composed of H and He produced in Big Bang amp heavier elements ejected by supernovas Star close to protoplanetary disk was destroyed by supernova amp the explosion sent a shockwave through disk As cloud from shockwave began to accelerate majority of disks mass concentrated towards center amp began to heat up Led to fusion of H and He which eventually led to formation of the Sun Small perturbations within disk caused new protoplanets to form Gravity caused matter to condense amp rest of protoplanetary area began separating into rings Larger objects collided amp became planets Earth formed 457 years ago Life did not evolve until 38 billion years ago Early Earth Hadean Hell Eon Lasted 800 million years No Oceans No free Oxygen Planet was fully molten No protective atmosphere Towards the end of Hadean Earth cooled in about 150 million years fast in geologic time Earth was bombarded by asteroids which caused cracks on the surface Steam amp gas was released and allowed for the formation of an atmosphere Clouds formed amp rain gave rise to oceans No ozone layer little UV protection Ends between 42 and 38 billion years ago with first signs of life DIOLUU LBCUH39B N OteS vveeK 1 Methods of Dating Relative Dating Can determine the age of rocks relative to one another First person to formally recognize this method of dating was 17th century Danish physician Nicolaus Steno Developed Principles of Stratigraphy Fossils of similar organisms are found in widely separated places on Earth Certain fossils are always found in younger strata while other fossils are always found in older strata Organisms found in younger strata are much more similar to present day organisms than those found in older strata Geologists could place fossils at relative ages with this method but still could not determine exact age of rocks Absolute Dating When radioactivity was discovered at the beginning of the 20th Century geologists were able to tell the exact age of rocks Radioisotopes decay in a predictable pattern over long periods of time A halflife is a specific time interval in which half of the atoms in the radioisotope decay to become stable nonradioactive isotopes Once an organism dies it ceases to exchange compounds with it s environment Paleontologists can use for example the ratio of 14C radioactive C isotope to 12C stable C isotope in fossils to determine their age This method is accurate only up to a certain point after 60000 years so little 14C remains that detection is difficult Different isotopes can be used to look farther back in time Optical Luminescent Used to determine when minerals were last exposed to daylight Time Scales Precambrian Paleozoic Mesozoic Cenozoic Note Tertiary now called PaleogeneNeogene DIOAUU LCCIUFC l l OICS VVCCK i EON ERA PERIOD EPQCH I Ma FOSSIL RECORD Human civilizations evolve great extinctions begin 03901 Ice Ages and interglacial periods cause widepread changes in climate 2396 Modern humans evolve and migrate around the world First ice ages begin as Himilayan Mountains rise Isthmus of Panama closes r 53 Most modern families of mammals evolve and migrate across land bridges Grasses evolve and spread worldwide Yellowstone Hotspot migrates eastward Colorado Plateau and Great Plains rise 23 Great Basin extension begins as San Andreas Fault System develops 339 Deciduous forests leaves fall in winter dominate temporate climates Rocky Mountains rise shedding sediments throughout western US region 56 Age of Mammals begins Western Interior Seaway vanishes W 66 Cretaceous 39ertiary boundary extinction wipes out dinosaurs ammonites etc Greenhouse Earth Dinosaurs at their peak 33 145 Western Interior Seaway forms in Great Plain region Q Breakup of Supercontinent Pangaea birds and early mammals appear E 201 Dinosaurs warm blooded replace reptiles cold blooded as dominant land animals a 252 End of Permian extinction greatest of all extinction events 299 Age of Reptiles Pangaea Supercontinent forms P DQSYIVapla 323 Carboniferous Period great coal swamps form as Appalachian Mountains form quot39553955399 39aquot 359 Age of Amphibians Age of Fishes 419 First forests coal beds appear 444 Age oflnvertebrates brachiopods trilobites corals 435 First land plants evolve First shelled invertebrates appear 541 Multicellular organisms evolve Modern continental shield regions of continents gradually assemble Banded lron Formations are deposited as oxygen atmosphere forms 2500 Stromatolites appear in fossil record singlecelled organisms evolve Pregam hriijan 4000 Oldest rocks preserved 4500 Solar System forms Moon and Earth system forms by accretion of extraterrestial materials Source http geologycafecom images timescalehighlightsjpg Paleozoic Era 543 MYA250 MYA Softshelled animals Cambrian Explosion Happened at beginning of Paleozoic All major animal groups developed during this period though new evidence suggests that life may have begun Precambrian New analysis suggests that Cambrian Explosion was actually no faster than any of the other diversification events in animal history Explosion of life occurred over a time span of 60 million years still pretty impressive 540 million years ago first land plants appear Previous to this all life occurred in water About 420 years ago first fish evolved legs amp began to walk on land Tiktaalik DIOLUU LBCUH39B N OteS week 1 Permian Extinction The Great Dying End of Paleozoic Up to 96 of all marine life and up to 70 of all terrestrial vertebrates went extinct Only known mass extinction of insects Mesozoic Era 250MYA65MYA Age of Reptiles Due to lack of animals there was a lot of room for adaptation of new groups reptiles took over Begins just before rise of dinosaurs About 200 MYA first mammals appear KT Extinction Mesozoic ends with another mass extinction event 65 MYA Note KT stands for CretaceousTertiary but the name Tertiary has been changed to PaleogeneNeogene KPg Extinction happened relatively quickly Associated with geologic signature known as KT boundary thin band of sedimentation found in certain parts of the world Scientists theorize that extinction was caused by mass asteroid impact or increased volcanic activity clouding the atmosphere and blocking the sun Nonavian dinosaur fossils are only found below this boundary indicating they went extinct immediately before KT event Cenozoic Era Age of Mammals 65MYApresent 2 MYA first humans appeared Earth has Changed Over Time Continental Drift Climate and atmosphere have been altered many times 5104 UU LBCUH39B N OteS Key Time Points Lecture 2b Time Event 46 BYA Earth Forms 40 BYA Earth begins to cool 38 BYA First Life forms 25 BYA Oxygen accumulates photosynthesis 17 BYA 1St Eukaryotes 1 BYA 1St Multicellular Organisms 450 MYA 1St Land Plants 420 MYA 1St Land Animals 250 MYA Permian Extinction 230 MYA 1St Dinosaurs 200 MYA 1St Mammals 65 MYA KT Extinction 2 MYA First Humans week i Panspermiatheory that life first evolved elsewhere in the universe but was seeded to Earth Life has 2 Characteristics Must be organized Must be able to replicate itself What Earth looked like 38 BYA Molten rock All life must have been aquatic No free Oxygen Created reducing atmosphere Electron adding molecules form very readily High Energy Environment Little to no UV blocking DIOLUU LBCUH39B N OteS week 1 4 Steps to Life on Early Earth 1 Abiotic Synthesis of Organic Molecules MillerUrey Experiment attempted to recreate Earth s early atmosphere in 1953 though their mixture of gasses was not exactly correct In early 1990 s we discovered that earth s early atmosphere was predominantly composed of C02 and N2 neither of which were found in original experiment New field of science arose titled PreBiotic Chemistry Conducting the Experiements Create atmosphere with variety of gasses Discharge sparks into atmosphere to simulate lightning Gasses cool and condense causing water droplets to fall Creates ocean Samplings of the more modern experimental oceans that form contain the building blocks of life amino acids nucleotides sugars lipids ATP and were formed in only one week 2 Formation of Polymers Polymers protein DNA form when monomers amino acids nucleotides get together and form a chain How in a vast ocean were these individual molecules able to find and attach to one another Clay Positively charged rich in iron and zinc which attracted negatively charged monomers Would indicate that first life formed near clayrich shores 3 Formation of Protobions Aggregates of abiotically produced organic molecules surrounded by a membrane Lipids Hydrophobic tails and hydrophilic heads form together to create liposome lipid bilayer Forms cavity that can hold chemicalsbegins to look like a cell 4 Origin of Heredity Material First hereditary material was likely RNA RNA can be formed abiotically more easily than DNA can Can replicate itself even more likely in presence of Zinc Contains hereditary information Has catalytic propertiescan act as an enzyme unlike DNA Recent research suggests that RNA can be composed completely of sugars and hydrogenous bases both components that would have been found on early Earth DIOLUU LBCUH39B N OteS week 1 Viroids Tiny particles of raw RNA smaller than a virus Lack even a single protein code to protect hereditary material Cause diseases in several plant families Contain as few as 250 nucleotides humans have 33 billion Enough genetic information to infect a plant and trick the plant s genetic machinery into replicating a viroid Because they cannot replicate on their own viroids still cannot be considered life May have been what led to life When does this become Life Scientists still have no real idea as to how life came about Synthetic Biologynew area of biological research that focuses on origin of life Some experiments attempt to create life from abiotic materials Theories of Evolution Supernatural Supreme being placed all organisms on Earth Organisms look amp function similar to Supreme Being Organisms do not change Anaximander 611546 BC Greek philosopher who wrote text called On Naturequot Introduced idea of evolution Theorized that life started as slime in the oceans and eventually moved to drier places To explain fossils he said that animals were born in spiny bark but as they grew the bark would dry up and break As humidity decreased oceans dried up and humans emerged Humans had to spend part of this transition inside the mouths of big fish to protect themselves from Earth s climate Common descent and transmutation of speciesradical ideas for his time Not until late 1700s early 18005 did many more people begin to explore these ideas Hutton Lamarck Darwin