2Why do we need to classify? Imagine a store…..how do you know where to find the milk or the cereal? Are they in the same aisle? How is the store “organized”? Are all stores similar?Imagine your computer or mp3 player…..are all of your songs and files in a single folder or do you have them grouped in some way?
3Evolution overviewAll life on earth began about 3.5 billion years ago with organisms that were a single cellThen one billion years ago organisms that are made of many cells appeared as a result of evolutionDuring evolution traits that do not help organisms survive disappear while good traits that help with survival remain
4ClassificationAs a result of evolution earth is populated by many different organisms with different traits.We group these organisms according to their similar characteristicsClassification – grouping and naming of organisms according to their evolutionary relationships and shared characteristics
5TaxonomyBranch of biology that deals with classification of life formsTaxonomist – use the tools of classification to identify and find relationships among organismsTaxonomists classify organisms based on their biochemical and genetic information, embryological development, fossil record, and evolutionary relationships, in addition to their body structure
6Early Classification and naming systems Aristotle – Greek philosopherInvented the first classification systemHe classified organisms into two major groups plants and animalsPlantsAnimalsLandWaterShrubsHerbsAirTrees
7Early Classification and naming systems continued . . . Carolus Linnaeus – Swedish botanistIn the 18th century developed a new classification systemHe also grouped them into plants and animalsHe classified animals based on their similar body structures and not where they livedExample: bats were grouped with mammals not with birds
8Binomial Nomenclature Linnaeus also gave each organism a two-word, Latin scientific nameThis is called binomial nomenclature – still used todayBinomial – consisting of two termsNomenclature – a system of names
9Bi-Nominal – two terms, two names How many names do you use to identify yourself?Example: Karen WoodBut why do we need this? Can we just call her Karen or simply that girl over there?
10….this is why we CLASSIFY When you have a lot of information, it is best to organize and group items so that you can find them easier or easily see their relationship to other items….this is why we CLASSIFYEven websites must organize their products
11Scientists also need a way to *NAME* organisms The “common names” used by people can sometimes be misleading or confusingIn order to communicate effectively, biologists need a CONSISTENT naming protocol.*Check out these slides of confusing names…..
12Sea Lion? Ant lion? Lion? Photo Credits Sea Lion: Bill Lim Ant Lion: Amphioxus Lion: law_kevenSea Lion?Ant lion?Lion?
13Which one of these is NOT actually a bear? Photo CreditsPanda: Chi KingKoala: BelgianchocolateBlack Bear: SparkyLeigh
14Bi-Nominal – two terms, two names: Genus and Species The first word in binomial nomenclature is called the genus which is a group that has one or more different species classified within itClosely related species that come from a common ancestorThe second word is species or a group of similar organisms that are capable of producing fertile offspring with each other
15Genus and Species Example: Panthera leo – lion and Panthera tigris – tigerBoth species are classified in the same genus Panthera along with other big cats however they are each a different species because they can’t reproduce with each otherGenus and species names are always italicized.First letter of the genus is always capitalized and the first letter of the species is always lower case.
16Taxonomic GroupingsTaxonomists classify things into seven major groups or taxaThey are:Kingdom – largest group of living things (broadest)Phylum – largest group within a kingdomClass – largest group within a phylumOrder – largest group within a classFamily – largest group within an orderGenus – largest group within a familySpecies – smallest group of living thing (most specific)HINT for remembering the order of the levels of classification:King Phillip Came Over For Great SpaghettiKing Phillip Cried Out For Great Soup
17Grouping Kingdom Phylum Class Order Family Genus Species Each group gets smaller and more specific – just think of the way you file things on your computer into folders and subfoldersKingdomPhylumClassOrderFamilyGenusSpecies
18To help you remember the list KING PHILIP CAME OVER FOR GREAT SOUPKingdom, Phylum, Class, Order, Family, Genus, Species
19Phylogenetic Taxonomy Taxonomists use two different approaches to place an organism into the correct taxonomic category:Systematics: a phylogenetic tree or family tree is used to show the evolutionary relationships between different groups of organismsThis process stresses common ancestors and relies on the amount of differences within a group to construct the treeTree is based on evidence from the fossil record, morphology, embryological development, biochemistry and genetic studies
20Phylogenetic Taxonomy Continued . . . Second approach used to place an organism into the correct taxonomic category is called cladisticsScientists construct a diagram based on specific characteristics of an organismThis is called a cladogram and its used to show evolutionary relationships among the different groups based on traits called shared derived characteristicsDerived characteristics – a trait that evolved only within the specific group under studyExample: Feathers in birds
21The scientific name is always the genus + species KingdomAnimaliaPhylumChordataClassMammaliaOrderPrimateFamilyHominidaeGenusHomoSpeciessapiensThe scientific name is always the genus + speciesHumans = Homo sapiensPhoto by atomicshark
22The scientific name is always the genus + species KingdomAnimaliaPhylumChordataClassMammaliaOrderPrimateFamilyHominidaeGenusHomoSpeciessapiensThe scientific name is always the genus + speciesHumans = Homo sapiensPhoto by atomicshark
23What are the scientific names of each of these organisms? LionTigerPintail DuckKingdomAnimaliaPhylumChordataClassMammaliaAvesOrderCarnivoraAnseriformesFamilyFelidaeAnatidaeGenusPantheraAnasSpeciesLeoTigrisacoutaWhat are the scientific names of each of these organisms?
24What is a species?Defined as organisms that can interbreed with one another, and produce fertile offspring
25When two organisms of different species interbreed, the offspring is called a HYBRID Is offspring fertile?Example: ligers and mules
27Phylogenetic Taxonomy Taxonomists use two different approaches to place an organism into the correct taxonomic category:Systematics: a phylogenetic tree or family tree is used to show the evolutionary relationships between different groups of organismsThis process stresses common ancestors and relies on the amount of differences within a group to construct the treeTree is based on evidence from the fossil record, morphology, embryological development, biochemistry and genetic studies
28Phylogenetic Taxonomy Continued . . . Second approach used to place an organism into the correct taxonomic category is called cladisticsScientists construct a diagram based on specific characteristics of an organismThis is called a cladogram and its used to show evolutionary relationships among the different groups based on traits called shared derived characteristicsDerived characteristics – a trait that evolved only within the specific group under studyExample: Feathers in birds
29Phylogenetics A cladogram has CLADES Clade – a monophylletic group - a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestorUsing a phylogeny, it is easy to tell if a group of lineages forms a clade. Imagine clipping a single branch off the phylogeny — all of the organisms on that pruned branch make up a clade.
32Classification into a kingdom is based on certain criteria - Number of cells (unicellular or multicellular)- How it obtains energy(heterotroph or autotroph)- Type of cell (eukaryote or prokaryote)
33Kingdom Animalia Multicellular Heterotrophic Most can move Photo by Tambako the JaguarMulticellularHeterotrophicMost can moveExamples: birds, insects, worms, mammals, reptiles, humans, anemonesPhoto by Eduardo Amorim
35Kingdom Fungae Multicellular (most) Heterotrophic (mainly decomposers) EukaryoticPhotos by nutmeg66
36Kingdom Protista Most are unicellular Can be heterotrophic or autotrophicEukaryotes (all have nucleus)Examples: Ameba, paramecium, euglena, algaeMost live in waterPhoto of Ameba by PROYECTO AGUA **/** WATER PROJECT
37Kingdom Eubacteria & Kingdom Archaebacteria UnicellularCan be autotrophic or heterotrophicProkaryotes (do not have a nucleus)Eubacteria = common bacteria (E. coli, Salmonella)Archaebacteria = “ancient bacteria”, exist in extreme environments
38Three Domain System Recently, scientists have added a group above Kingdom. Three groups, called DOMAINS, contain each of the six kingdoms.Domain Eukarya - includes organisms composed of eukaryotic cells (plants, animals, fungi, protists – 4 kingdoms)Domain Bacteria - includes all prokaryotic cells, Kingdom EubacteriaDomain Archaea - includes only "ancient" bacteria, Archaebacteria (1 kingdom)
39Dichotomous KeyPrecise method that helps taxonomists classify and identify unknown organismsMade up of a list of observable, alternative characteristics, that leads, step by step, to the correct identification of an organismDichotomous means dividing in two because there are always two choices at each stepAt each step the organism will have only one of the traits described and that is the path you follow
40Example:A dichotomous key for a plant would have one step where you chose between spores and seeds as a method of reproductionThen it might ask for seeds if its cones or flowersThere would also be steps asking about leave structure and the stem
42Molecular Phylogenetics and what it all means......
43Chips and Candy vs. Living things Using only physical characteristics or evolutionary relationships?
44Molecular Phylogenetics Constructing trees based on DNA sequence comparisonsIn certain stretches of DNA mutations occur at reliable rates - the more mutations the DNA has accumulated, the longer since it split off from its ancestral sequenceMay use RNA (for RNA viruses) or protein sequences
45Molecular Phylogenetics Made possible by the availability of whole genome sequencing; new technologies make this faster – more organisms genomes sequencedMany species genomes have been sequencedRequires "Bioinformatics" – computer algorithms that compare sequences from multiple organismsComparison – align sequences, determine similarities, differences, gaps in alignment
49Clades are nested within one another — they form a nested hierarchy Clades are nested within one another — they form a nested hierarchy. A clade may include many thousands of species or just a few. A clade may include species that are no longer living (extinct)
53How do we know the time?Life began 3.8 billion years ago, and insects diversified 290 million years ago, but the human and chimpanzee lineages diverged only five million years ago.How have scientists figured out the dates of long past evolutionary events?Here are some of the methods and evidence that scientists use to put dates on events: Radiometric dating; stratigraphy; molecular clocks
55Molecular ClocksEvolutionary changes may occur in a clock-like fashionChanges in DNA sequence can build up over the course of million years at a reliable rateExample: Alpha-globin gene experiences base changes at a rate of .56 changes per base pair per billion years - IF this rate is reliable, the gene could be used as a molecular clock.
56Evolution and Trees beyond Taxonomy Phylogenetics can be used to build NEW scientific knowledge:Identifying the source of new human diseases;Setting Conservation prioritiesAgricultureInvestigating alleged crimesUse of 'model' organisms in biomedical science
58Investigating Alleged crimes Despite overwhelming evidence attesting to their innocence, last month six medical workers were sentenced to death in a Libyan trial.The crime with which the five Bulgarian nurses and one Palestinian doctor are charged is indeed horrifying. After an outbreak of HIV at the Al-Fateh hospital, the Libyan government accused the defendants of committing an act of bioterrorism by deliberately injecting 426 hospitalized children with HIV-tainted blood.The HIV strain is particularly virulent and has already contributed to the deaths of more than 50 of the infected children.
59Investigating Alleged crimes The children had been infected and their viruses had begun diverging several years before the medics even arrived on the scene!
60'Model' OrganismsCommon ancestor – common morphology, common processes; common developmentCan be used to study human development in the laboratory using 'model' organismsModel human processes on studies performed in other organismsSome examples:
61Use of Model OrganismsStudy of common cellular processes – cell division, glycolysis studied in bakers yeastStudy of common developmental process – human limb development in chickenScreen for new drugs – which chemicals activate or block common/similar cellular pathways altered in human disease (e.g. cancer)Toxicology – determine safety of compounds before human use
62Think about it!The development and safety of all modern medicines, cosmetic products, etc. is based on the Theory of Evolution and Modern PhylogeneticsThe development of new Crops is based on the Theory of Evolution and Modern PhylogeneticsConservation Biology is based on the Theory of Evolution and Modern Phylogenetics
63Evolution is an inseparable part of ALL Life Science – Medicine -Agriculture