Week one diversity of life
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This 10 page Class Notes was uploaded by Sierra Hellwitz on Thursday September 11, 2014. The Class Notes belongs to 210 at a university taught by a professor in Fall. Since its upload, it has received 118 views.
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Date Created: 09/11/14
History of Life on Earth EFB 210 Fall 2014 1 Geologic Timeline Eon era epox Origin of earth 46 billion years ago first life arises 38 bill most evolution happens in the last 6 million years A Archean Eon 38 billion 25 billion years ago low oxygen environement first life arises chemoautotrophic metabolizes energy based on chemical energy hydrogen sulfide etc prokaryotes 38 bill years ago Cyanobaeteria start photosynthesizing at the end of this period begins from dissolved iron in water oxidizes and rusts oxygen from the cyanobacteria and kept oxygen in the water B Proterozoic Eon 25 billion 545 million years ago Proterozoic early life stromatolite great oxygenation event greatest pollution event on earth iron could not absorb the oxygen in the water any more and it moved into the air Eukaryotes evolve life dominated by small soft0bodied eukaryotes until Cambrian explosion small soft bodied organisms don t fossilize as well 1 Cryogenian Period 850 635 mya cryose cold genesis beginning snowball earth massive ice ages glaciation probably reaching to equator maybe 2 Ediacaran Vendian Period 635 545 mya proliferation of multicellular softbodied organisms difficult to determine what exactly happened during this period extensive ocean habitat C Paleozoic Era 545 248 mya old life 1 Cambrian Period 545 495 mya major diversification of form and function Cambrian explosion very well fossilized most major phyla occur origin of general body plan for metazoans marine life still dominant trilobites arthropod incredibly diverse nautiloids cephalopods 2 Ordovician Period 495 443 mya shallow seas first vet with tue bones first life on land 3 Silurian Period 443 417 mya life on land progresses Slowly land becomes easier to live on first appearance of vascular plants major diversification of fish 4 Devonian Period 417 354 mya significant radiation of life on land tetrapods and arthropods colonize land anphibians 5 Carboniferous Period 3 54 290 mya plant reach heyday coal cover most of land and were huge reptiles appear warm swampy climate extensive forests generate massive coal reserves Mississippian and Pennsylvanian together 6 Permian Period 290 248 mya supercontinent pangea starts with ice age and ends with the biggest extinction event in earth s history D Mesozoic Era 248 65 mya age of the Dinosaurs reptiles Fragmentation of Pangaea leads to much speciation l Triassic Period 248 205 mya warm arid climate slow recovery from Permian extinction mammals and dinosaurs evolve 2 Jurassic Period 205 142 mya first birds appear largest land animals of all time present 3 Cretaceous Period 142 65 mya sea levels reached highest point angiosperms appear most evolutionarily advanced plants finally occur E Cenozoic Era 65 mya present mammals dominate on land in absence of dinosaurs Pleistocene Epoch last major ice ages 1014 million years ago large effect on NY soil composition etc Holocene Epoch after ice age allows for species radiation II Major Themes in Evolutionary Time A Mass Extinction Events relatively short events resulting in massive species loss The big 5 1 EndOrdovician 2 Late Devonian 3 Permian largest mass extinction occurred in pulses 95 of all species loss probably due to gradual environmental changes and a catastrophic event 4 EndTriassic 5 CretaceousTertiary EndCretaceous dinosaur extinction 7080 species lost probable cause asteroid impact sea levels dropped intense volcanic activity B The history of life was not neatly progressive C Natural selection was not the only driver of evolutionary change isolationism extinctions random events etc EON ERA PERIOD Precambrian Phanerozoic EPOCH Holocene Quaternary Pleistocene Pliocene 2 5 u Cretaceous Jurassic Mesozoic Triassic Permian Pennsylvanian Mississippian Paleozoic Late Middle Early Cambrian httpup10adwikimedia 0rgwikipedia c0mm0ns 2 22 Ge010gictimes cale jpg 82814 What is biodiversity 1 General definition the variation at all levels of life 2 Types of biodiversity a Genetic Diversity components of the genetic coding that structures organisms nucleotides genes chromosomes and variation in the genetic make up between individuals within a population and between populations b Organismal diversity the taxonomic hierarchy and its components from individuals to species genera and beyond 1 species richness number of species in the area 2 species evenness how abundant each species is within that area c Ecological ecosystem diversity ecological differences between habitats and biomes d Levels of biodiversity 1 alpha diversity within one area ecosystem a county etc 2 beta diversity differences in species diversity between ecosystems 3 gamma diversity overall diversity for the different ecosystems in a broad region How many extant species are there Approximately 15 million describes species how are they distributed across taxa Estimated to be 13 million extant species 1 range 35 1115 million 2 Major uncertainties lie in particular a taxonomic groups eg bacteria fungi inverts b functional groups eg parasites difficult to find c habitats or biomes eg soils deep ocean Measuring biodiversity A extrapolation 1 canvassing experts estimate overall species based on opinions of experts in many taxonomic groups Assume that experts know groups well enough to make reliable estimates 2 patterns of species description using past patterns eg rates of species description in a taxonomic group or groups to estimate cumulative unknown species Assumes rate of change remains constant 3 proportion of undescribed species using ratios of known and 4 5 unknown species over time from large samples of specimens to estimate overall numbers of known species Assumes wellstudied areas using areas where species number is reasonably well known to estimate over larger areas Assumes the areas where overall species numbers are well known are representative of those for which they are not compare an arctic tundra to a tropical rainforest wellstudied groups using well known groups mammals and their proportion to overall species in wellstudied areas to estimate overall numbers Assumes rations of the numbers of species in well known and other groups remain reasonably constant across space B Diversity indices Quantitative measures of diversity that take into account both richness and evenness Ex Shannon Wiener index Simpson index some emphasize richness over evenness or vice versa some are very sensitive to sample size etc Does biodiversity matter A Direct use values 1 Food how many species we can versus do use for food 2 Medicine willow trees for aspirin poppies etc 3 Bio control 4 industrial materials wood waxes adhesives etc 5 recreational harvesting brings in tens of millions to economies yearly 13 C 6 Indirect use values 1 Ecosystem services carbon sequestering nutrient cycling pollination soil formation food web etc far more difficult to artificially recreate Non use values 1 2 3 4 optional value saved for future use medicine plants interesting compounds etc bequest value leave intact for future generations existence value human value placed on living things ie empathy intrinsic value right to exist because they are Pie chart Viruses and prokaryotes 01 Invert 66 protist 11 plant 4 vertebrate animals 1 1 fungi 3 Taxonomy and Systematics Describing Biodiversity EFB 210 Fall 2014 I Taxonomic History taxonomy the science of naming describing and classifying living things one aspect of systematics taxon pl taxa a group of organisms at a particular level of a classification system A Aristotle 1 Greek philosopher 2 first taxonomist 3 classified organisms as either plant or animal Animals functionality land water air dwellers Plants stem differences B Greeks and Romans 1 Expanded on Aristotle s system 2 first to organize like organisms in genera the Latin word for groups C Middle Ages I began using latin to systematically record names 2 polynomial system a series of descriptive terms added to the name of a genus to refer to a particular organism very long and complicated but descriptive D Carolus Linnaeus Carl von Linne 17071778 1 Swedish biologist Latinized his name 2 set out to catalog all organisms 3 developed binomial system as shorthand genus species his short hand kingdom downward system also attributed to Linnaeus add domain Achaea eubacteria eukarya II Describing Species A character any recognizable trait feature or property of an organism ex eye color leaf shape character state discrete condition of character eye color blue leaf shape simple B New Species 1 Name it using a unique binomial latin name 2 Specify rank of taxon eg species subspecies 3 Designate a type specimen and deposit it at an appropriate institution a holotype organism on which species description is based b isotype collected at same place and time as holotype multiples backups c paratype same specimen type collected at different place or time 4 Describe species traditionally in Latin or English 5 Publish name and description in peerreviewed journal C New species descriptions also need to be completed when species are Split or lumped Baltimore oriole and bullocks oriole Yellow rumped warbler now one species D Some Taxonomic Guidelines 1 Genus and species names must always be italicized or underlined 2 species name is never capitalized All other forms are 3 species name is never written alone the genus always with it or abbreviated C rufus 4 intermediate taxonomic level can be created using appropriate pre xes 5 international groups maintain international rules and regulations e g International Code of Botanical Nomenclature ICBN International Code of Zoological Nomenclature ICZN III Systematics Today A Organizing biodiversity has more recently focused on evolutionary relationships systematists analyze how organisms are related based on how they evolved systematics the study of the diversity of organisms and their evolutionary relationships phylogeny the evolutionary history of a taxon B Constructing a Cladogram Cladistics l Cladograms are a simplified visualization of a taxon s evolutionary history 2 character states are used to group related organisms a synapomorphy a newly derived character state shared by all members of a taxon b clade a group containing a common ancestor and all taxa descending from it c group types monophyletic includes the most recent common ancestor and all of its descendants paraphyletic includes the most recent common ancestor but not all of its descendants polyphyletic grouping derived from more than one ancestor succulents outgroup the least related taxon mosses outgroup to plants 3 Typically shows a progression from simple to advanced 4 Not always one correct organization but typically the most parsimonious is preferred