Systematics The Science of Biological Diversity and its Evolutionary History Goal Discover all the branches of the phylogenetic tree of life o Same as the evolutionary tree of life Tree of life relationship of all organisms with one ancestral species at base o Find relationships of all organisms and the base Why do we care about systematics o Economic o Public health WHO Global Influenza Surveillance Network o New vaccines every year to combat the flu o Legal ex Jeremy Brown and HIV o From LSU had to testify in court about a man that was infecting people with HIV He determined HIV was given to the women by the man o It s cool Topics of Chapter 18 o How Are Organisms Named and Classified o What Are the Domains of Life o Why Do Classifications Change o How Many Species Exist Taxonomy What s in a name Alice in Wonderland important to know species by their names Taxonomy branch of biology with the goal of naming and classifying all species Carolus Linnaeus 1707 1778 father of taxonomy Species plantarum 1753 From polynomial phrase names to binomial part 2 system of nomenclature Genus species ex Homo sapiens Catnip example Nepeta floribus interrupte spicatus pedunculatis meaning Nepeta with flowers in an interrupted pedunculate spike Linnaeus wrote cataria in the margin of the text Name became Nepeta cataria Starting point of nomenclature as it exists today Allowed for easy identification of plants by placing every genus into an artificial class and order Marks the beginning of a great upsurge in the popularity of science and arguably is amongst the most important publications in biology ever The two part scientific name of an organism is formed from the genus and specific epithet A genus is a group that includes a number of very closely related species A species within a genus includes populations of organisms that can potentially interbreed under natural conditions Three Species of Bluebird Classification originated as a hierarchy of categories Each species was placed in a series of hierarchically arranged categories on the basis of resemblance to other species The categories form a nested hierarchy in which each level included all the other levels below it The Linnaean classification system came to include eight major categories or taxonomic ranks sapiens Taxa within categories Example Macbridea caroliniana Homo Class Mammalia Specific epithet sapiens Family Hominidae Domain Eukarya Kingdom Animalia Order Primates Phylum Chordata Genus Homo plural genera Did King Phillip Come Over For Good Spaghetti Put in order of most to least inclusive 8 28 13 Modern classification emphasizes patterns of evolutionary descent In 1859 Charles Darwin 1809 1882 published On the Origin of Species ancestry relatedness This work demonstrated that all life is related by common Taxonomic categories should reflect evolutionary The more categories two organisms share the closer their evolutionary relationship Today the process of classification focuses on reconstructing phylogeny or evolutionary history The science of reconstructing phylogeny is known as systematics Systematists have increasingly focused their efforts on building evolutionary trees rather than dividing organisms into specific Linnaean classifications Systematists name groups which they call clades that include species linked by descent from a common ancestor Clades can be arranged in a hierarchy with smaller clades nested within larger ones Clades Form a Nested Hierarchy Anatomy plays a key role in systematics Historically the most important and useful distinguishing characteristics have been anatomical Systematists look for similarities in both external body structure and internal structures such as skeletons and muscles Molecular similarities are also useful for reconstructing phylogeny Systematists examine genetic similarities between DNA nucleotide sequences It has been estimated that 96 of the chimpanzee genome is identical with that of humans Similarities in chromosome structure also can be used to establish relationships between organisms Human and Chimp Chromosomes Are Similar Different approaches to classification Artificial systems aid to identification using few characters Theophrastus Father of Botany classified by form Tree shrub herb Linnaeus based on floral characters Natural classifications reflect evolutionary history Phylogenetic trees diagram evolutionary relationships among organisms An early phylogenetic tree in The History of Creation by Earnst Haeckel 1866 To reflect phylogeny accurately each taxon is ideally monophyletic Monophyletic group Paraphyletic group common ancesrot Polyphyletic group members of the group an ancestor and all its descendants clade contains some but not all descendants of a does not include the common ancestor of all Homologous features help determine evolutionary relationships Homoplasy analogy similar in function with different origin due to Analogous traits similar in function w different origin due to common origin convergent evolution convergent evolution Convergent evolution Describes the independent evolution of similar features in species of diff lineages Number of Domains Before 1970 systematists divided all species into two groups animalia plantae including plants bacteria fungi and photosynthetic eukaryotes As knowledge expanded of life s evolutionary relationships it became clear that a two domain approach was an oversimplification Why the number of domains changed Carl Woese discovered that prokaryotic organisms included two very distinct groups Bacteria Archaea on the basis of their respective nucleotide sequences of ribosomal RNA famous for defining the Archaea a new domain in 1977 by phylogenetic taxonomy Two Domains of Prokaryotic organisms Organisms The Three Domains Eukaryotes cells with nuclei and other organelles Prokaryote true bacteria lack organelles Archaea have bacteria like genes but with eukaryote like information processing Molecular techniques have revolutionized systematics these three domains split very early in life long before plants and animals evolved Systematics The Science of Biological Diversity and its Evolutionary History Goal Tree of life the world organisms The Tree of Life organisms Tree of Life Web Project ToL collaboration of biologists from all over The project provides information about the diversity of organisms on Earth their evolutionary history phylogeny and characteristics Each page contains information about a particular group of Within
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