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Finding Order in Diversity

Finding Order in Diversity. Classification. Why 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?

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Finding Order in Diversity

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  1. Finding Order in Diversity Classification

  2. Why 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?

  3. Evolution overview • All life on earth began about 3.5 billion years ago with organisms that were a single cell • Then one billion years ago organisms that are made of many cells appeared as a result of evolution • During evolution traits that do not help organisms survive disappear while good traits that help with survival remain

  4. Classification • As a result of evolution earth is populated by many different organisms with different traits. • We group these organisms according to their similar characteristics • Classification – grouping and naming of organisms according to their evolutionary relationships and shared characteristics

  5. Taxonomy • Branch of biology that deals with classification of life forms • Taxonomist – use the tools of classification to identify and find relationships among organisms • Taxonomists classify organisms based on their biochemical and genetic information, embryological development, fossil record, and evolutionary relationships, in addition to their body structure

  6. Land Water Shrubs Herbs Early Classification and naming systems • Aristotle – Greek philosopher • Invented the first classification system • He classified organisms into two major groups plants and animals Plants Animals Air Trees

  7. Early Classification and naming systems continued . . . • Carolus Linnaeus – Swedish botanist • In the 18th century developed a new classification system • He also grouped them into plants and animals • He classified animals based on their similar body structures and not where they lived • Example: bats were grouped with mammals not with birds

  8. Binomial Nomenclature • Linnaeus also gave each organism a two-word, Latin scientific name • This is called binomial nomenclature – still used today • Binomial – consisting of two terms • Nomenclature – a system of names

  9. Bi-Nominal – two terms, two names • How many names do you use to identify yourself? • Example: Karen Wood • But why do we need this? Can we just call her Karen or simply that girl over there?

  10. 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 CLASSIFY Even websites must  organize their products

  11. Scientists also need a way to *NAME* organisms • The “common names” used by people  can sometimes be misleading or confusing • In order to communicate effectively, biologists need a CONSISTENT naming protocol. • *Check out these slides of confusing names…..

  12. Photo Credits Sea Lion: Bill Lim Ant Lion: AmphioxusLion: law_keven Sea Lion? Ant lion? Lion?

  13. Which one of these is NOT actually a bear? Photo Credits Panda: Chi King Koala: Belgianchocolate Black Bear: SparkyLeigh

  14. Bi-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 it • Closely related species that come from a common ancestor • The second word is species or a group of similar organisms that are capable of producing fertile offspring with each other

  15. Genus and Species Example: • Pantheraleo – lion andPantheratigris – tiger • Both species are classified in the same genus Pantheraalong with other big cats however they are each a different species because they can’t reproduce with each other • Genus 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.

  16. Taxonomic Groupings • Taxonomists classify things into seven major groups or taxa • They are: • Kingdom – largest group of living things (broadest) • Phylum – largest group within a kingdom • Class – largest group within a phylum • Order – largest group within a class • Family – largest group within an order • Genus – largest group within a family • Species – smallest group of living thing (most specific) • HINT for remembering the order of the levels of classification: • King Phillip Came Over For Great Spaghetti • King Phillip Cried Out For Great Soup

  17. Grouping Each group gets smaller and more specific – just think of the way you file things on your computer into folders and subfolders • Kingdom • Phylum • Class • Order • Family • Genus • Species

  18. To help you remember the list KING PHILIP CAME OVER FOR GREAT SOUP Kingdom, Phylum, Class, Order, Family, Genus, Species

  19. Phylogenetic 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 organisms • This process stresses common ancestors and relies on the amount of differences within a group to construct the tree • Tree is based on evidence from the fossil record, morphology, embryological development, biochemistry and genetic studies

  20. Phylogenetic Taxonomy Continued . . . • Second approach used to place an organism into the correct taxonomic category is called cladistics • Scientists construct a diagram based on specific characteristics of an organism • This is called a cladogram and its used to show evolutionary relationships among the different groups based on traits called shared derived characteristics • Derived characteristics – a trait that evolved only within the specific group under study • Example: Feathers in birds

  21. The scientific name is always the genus + species Humans = Homo sapiens Photo by atomicshark

  22. The scientific name is always the genus + species Humans = Homo sapiens Photo by atomicshark

  23. What are the scientific names of each of these organisms?

  24. Defined as organisms that can interbreed with one another, and produce fertile offspring What is a species?

  25. Example:  ligers and mules When two organisms of different species interbreed, the offspring is called a HYBRID Is offspring fertile?

  26. Phylogenetic 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 organisms • This process stresses common ancestors and relies on the amount of differences within a group to construct the tree • Tree is based on evidence from the fossil record, morphology, embryological development, biochemistry and genetic studies

  27. Phylogenetic Taxonomy Continued . . . • Second approach used to place an organism into the correct taxonomic category is called cladistics • Scientists construct a diagram based on specific characteristics of an organism • This is called a cladogram and its used to show evolutionary relationships among the different groups based on traits called shared derived characteristics • Derived characteristics – a trait that evolved only within the specific group under study • Example: Feathers in birds

  28. Phylogenetics • A cladogram has CLADES • Clade – a monophylletic group - a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor • Using 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.

  29. The Kingdoms There are currently 6 kingdoms

  30. Classification 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)

  31. Kingdom Animalia Photo by Tambako the Jaguar • Multicellular • Heterotrophic • Most can move • Examples: birds, insects, worms, mammals, reptiles, humans, anemones Photo by Eduardo Amorim

  32. Kingdom Plantae • Multicellular • Autotrophic • Eukaryotic • Cannot move • (due to cell walls)

  33. Kingdom Fungae • Multicellular (most) • Heterotrophic (mainly decomposers) • Eukaryotic Photos by nutmeg66

  34. Kingdom Protista • Most are unicellular • Can be heterotrophic or autotrophic • Eukaryotes (all have nucleus) • Examples: Ameba, paramecium, euglena, algae • Most live in water Photo of Ameba by PROYECTO AGUA **/** WATER PROJECT

  35. Kingdom Eubacteria & Kingdom Archaebacteria • Unicellular • Can be autotrophic or heterotrophic • Prokaryotes (do not have a nucleus) Eubacteria = common bacteria (E. coli, Salmonella) Archaebacteria = “ancient bacteria”, exist in extreme environments

  36. 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 Eubacteria Domain Archaea - includes only "ancient" bacteria, Archaebacteria (1 kingdom) Three Domain System    

  37. Dichotomous Key • Precise method that helps taxonomists classify and identify unknown organisms • Made up of a list of observable, alternative characteristics, that leads, step by step, to the correct identification of an organism • Dichotomous means dividing in two because there are always two choices at each step • At each step the organism will have only one of the traits described and that is the path you follow

  38. Example: • A dichotomous key for a plant would have one step where you chose between spores and seeds as a method of reproduction • Then it might ask for seeds if its cones or flowers • There would also be steps asking about leave structure and the stem

  39. Molecular Phylogenetics and what it all means......

  40. Chips and Candy vs. Living things Using only physical characteristics or evolutionary relationships?

  41. Molecular Phylogenetics • Constructing trees based on DNA sequence comparisons • In 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 sequence • May use RNA (for RNA viruses) or protein sequences

  42. Molecular Phylogenetics • Made possible by the availability of whole genome sequencing; new technologies make this faster – more organisms genomes sequenced • Many species genomes have been sequenced • Requires "Bioinformatics" – computer algorithms that compare sequences from multiple organisms • Comparison – align sequences, determine similarities, differences, gaps in alignment

  43. Genomes sequenced

  44. What's in a Clade

  45. 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)

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