BI102 - Week 7
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This 5 page Class Notes was uploaded by Markhame on Thursday February 18, 2016. The Class Notes belongs to BI 102 at Oregon State University taught by Dr. Lesley Blair and Mark Lavery in Winter 2016. Since its upload, it has received 37 views. For similar materials see General Biology - Genetics in Biology at Oregon State University.
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Date Created: 02/18/16
Week 7 Final Exam Material Begins Tuesday, February 16, 2016 10:01 AM Tuesday 2/16/2016 Eons of Life "A tour through four billion years of life" Precambrian → 4.6/4.0bya (billion years ago) → How old the world actually is. → Billions of years covered Phanerozoic → 544mya (what we used to believe the age of the earth was) Paleozoic ‐ ancient Mesozoic ‐ middle Cenozoic ‐ current (now) Precambrian Supereon (super‐ eon) Geology: Stratigraphy → Rock Strata (layers), including fossils The further down in the earth we dig, the further back in time we go Each layer can indicate how old fossils are when we find them Geochronology → Geologic time, radiometric dating Decay rates of atoms into ions ‐ use this to approximate when a fossilized animal died More accuracy than we've ever had Key: These two things work together to help us learn about time Geologic Time Supereon Eon Era Period Precambrian Supereon (4.6 bya ‐ 544 mya) Time before Phanerozoic Eon Hadean → earliest time period on earth, everything is hot/on fire/ molten; earth/rocks are forming in clumps, gas is beginning to precipitate into water (oceans forming/water is forming) Archean → More and more rocks depositing, beginning of continents → Amino acids are forming: Gases + Water + Energy → Amino Acids DNA/RNA needed to organize amino acids to make proteins → Searching for how amino acids can come together to form life in these times (We don't know how yet) Hadean + Archean = Precambrian Supereon Bacteria formed in Hadean Geological Time Clock "Microbial mats" in low‐oxygen waters Can't exist without some form of life. By 2.8 bya: Cyanobacteria carry out photosynthesis Oxygen in atmosphere by Proterozoic Eon ANIMALS: Ancestors of jellyfish, sea fans, etc. begin in Proterozoic Paleozoic Era 544 mya ‐ 245 mya → "Cambrian Explosion" → Hard‐shelled fossils Trilobites (macroscopic) → First Vertebrate (spinal column) animals The first : Fish Cartilage then bones protecting the spinal chord Pangaea → All the land above water gets stuck together into one land mass Any land organisms can freely wander and migrate across the entire land mass Plants forming on Land: Brings on insects Beginnings of ferns and trees First Vertebrates on land: Amphibians (water + land) → Reptiles (fully on land) End of Paleozoic → 90% of spcies suddenly go extinct Mass extinction → Global warming? Mesozoic Era 245 mya ‐ 65 mya → Triassic, Jurassic, Cretaceous AGE OF THE REPTILES → Dinosaurs In the water: Ammonites → mollusks Index fossils: Widespread in a particular time period Ammonite fossils are highly sought‐after Out of water: Insects Diversify MAMMALS Pretty small, eaten by the larger reptiles Relatively insignificant Not nearly as dominant as reptiles are End of Mesozoic Era → 75% of species go extinct → Meteorite? Climate change → Changes atmosphere → allows meteorite in to destroy things *Only surviving dinosaurs → Birds Cenozoic Era 65 mya ‐ Present → Tertiary, Quarternary AGE OF THE MAMMALS: Herds of mammals, getting bigger and increasing in numbers Grasses are spreading around the world (habitat formation) Mammals (including humans) would not be the same if it wasn't for grass Diatoms ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Thursday 2/18/2016 Extinctions "Genetics plays a key role in species extinctions" Mass Extinctions Family → a bunch of different species that share a lot of similarities → There are 5 mass extinctions that we know of Causes of Mass Extinctions: Catastrophes (meteorite, volcanic eruption, etc.) Climate Change (severe, mass‐scale; NOT ICE AGES ‐ ice ages are small) Severe change in atmosphere and water temperature Other species (as other species change and evolve, it can cause its predators or competitor species to die) Humans → not included in our timeline → HUMANS: We directly take over other species' habitats Indirectly ‐ industrial pollution 2 MASS EXTINCTIONS WE ARE GOING TO FOCUS ON 1.Permian Mass Extinction (Ends Paleozoic) a.P‐T Extinction → 250 mya iPermian → Triassic b.Most life was still in the oceans iWiped out about 90% of species. iiLikely most of them were temperature dependent a. Ocean temperature changes (heated up) c.Cause: Climate Change + Catastrophe *ENTER: RISE OF THE REPTILES* 2.Cretaceous mass extinctions ( end of Mesozoic) a.K‐T Extinction → 65 mya → Renamed K‐Pg iEND OF THE DINOSAURS/REPTILES b.Only birds and small reptiles survive c. Modern fauna → Increasing in diversity rapidly; Supports the rise of mammals. d. Cause: Catastrophe + Climate Change i.Catastrophe = Meteorite iiAlso possibility of a series of volcanic eruptions after the meteorite e. Still not as many extinctions as P‐T i.Approx. 75% of species *Earth's Current Total Number of Species = Approx. 10+ million* Most of these are microscopic bacteria species Estimation of extinction = Approx. 10,000 Species/year On par with the P‐T Extinction Most of them are microscopic We probably don't even pay attention to these We usually only care about birds and mammals BIRDS: → The Dodo Identified in 1598; extinct in 1662 Mauritius ‐ tiny island off the southeast coast of Africa Went extinct from explorers/sailors who hunted them on their island Possibly a relative of pigeons (we only have shitty drawings of them) → Passenger Pigeons 3+ Billion in 1850; extinct in 1914 A single flock flying overhead could have had 1+ million in it WHY ARE THERE ABSOLUTELY NONE??? Genetic Diversity → Loss of Genetic Diversity The Bottleneck Effect Parent Gen. Next Gen. Causes of Loss of genetic diversity: Habitat Loss → Examples: Northern Elephant Seal 20 in 1890; 200,000 Now They have very low genetic diversity, living in protection Diseases affect mass amounts of them because their immune systems are all basically the same Cheetahs Massive genetic issues in their DNA (and it's dominant) Mortality rates are steadily rising because of this ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ → LIGER (male lion + tiger) Trying to fix the bottlenecking of Tigers and Lions → Trying to artificially make genetic diversity → But hybrids are sterile But why are we doing this? → Are species Important? "Wild" Genes Agriculture: Genes from wild strawberries → wild strawberries found in Utah Didn't taste so good Mixed them with domestic strawberry Everbearing Strawberries → grow year‐round and produce a lot of them Could not have been produced w/o wild genes from the wild strawberries Genes from wild blueberries → Can grow in more extreme conditions than cultivated blueberies Crossed w/ domestic blueberries Drought ‐ resistant blueberries Could not have done this w/o wild genes from wild blueberries Medicine: Periwinkle Flower (Madagascar) Has a chemical that fights certain types of Leukemia (bone marrow cancer) Calophyllum Tree (Indonesia) Chemical that assists the body in fighting HIV Habitat Maintenance: → National Wildlife Refuges Set aside land and try to save the habitat to protect and save species DNA/Genome Banks: → Collecting genetic material and chrigenically storing it with the hope of extracting it at a later time → Preserving and researching genetic material *This is a desperate measure* Breeding Programs: → Giant Panda: Bottleneck genetic issue of bears 43,000 years ago; can only eat Bamboo → 280 in captivity; 1,000+ in the wild → They are basically just a horrific genetic mess; they don't even breed very well and can crush their babies →Takes massive efforts to keep these alive
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