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TAXONOMY: Organizing Life’s Diversity “Random” Facts • It is estimated that there are between 3 and 30 million species on this planet. • We have named about 1 million animal species, and a half million species of microorganisms and plants. • We are further along with some species than others. So how do you organize the diversity of life? • Use your classification skills… • Taxonomy: branch of biology that is concerned with the identifying, naming and classification of organisms NOT TAXIDERMY! John Ray, 1600’s: • “When men do not know the name and properties of natural objects – they cannot see and record accurately.” The Cat of Many Names… Puma concolor 1700’s • Carl von Linne = Linnaeus • Father of Taxonomy • Systema Naturae Binomial Naming System • Genus: generic, descriptive of similar species, thought to be the same type of organism • Specific Name/epithet: in combo with genus, identifies one specific organism • • • • • Bufo americanus Mustella vison Escherichia coli Canus lupus Turdus migratorius • Linnaean scheme based on perceived similarities or differences in morphological traits Species… • • • • Biological species concept Ecological species concept Morphological species concept Genealogical species concept Olinguito: first mammalian carnivore species newly identified in the Americas in 35 years. Why does it matter? Linnaeus: Father of Taxonomy • Binomial system = core organizing unit for classification scheme Back in the ancient days... • Lumped all livings into two groups: plants and animals • 14 groups – mammals, bird, fish, etc • Subdivided those by size of organisms 1500’s – 1700’s • Age of European global exploration • Identification and description • Invention of the light microscope (1600’s) Rethinking Classification • 2 Kingdom System • Plants and Animals • Persisted for quite awhile • Fungi and bacteria = plants • 1800’s, added third = protists The hierarchy today…(an enhanced version of Linnaeus’ scheme) • • • • • • • Kingdom (most inclusive) Phylum Class Order Family Genus Species (most exclusive) Patterns of Relationships • Higher taxa • Reflect relationships among species LIONS, TIGERS, AND HOUSE CATS… Most general grouping? Most specific grouping? Whittaker’s System (circa 1969) • 5 Kingdoms • Today, we say that there are 6 kingdoms • Domains Let’s practice…group the following objects into two categories: Then keep breaking them into smaller groups… Where would this fit in? Successful for 20+ years… • Recognized two fundamentally different types of cells (pro vs euk) • Levels of organization (uni vs multi) • Recognized three kingdoms of multicellular eukaryotes based on modes of nutrition But… • There appeared to be two distinct lines of bacteria (prokaryotes) • There were the nagging protists… • AND…new genetic innovations help complicate things • And it led to… Domains: Superkingdoms Lumpers vs Splitters • You can continue to subdivide categories… • Ex: superorder, order, suborder, and infraorder • and ultimately end up with 30+ different categories that can be used to classify Take Home Message(s) • Classification today is based on evolutionary relationships • Increased complexity makes more variations possible • More confident in groupings of families down than about relationships among the major groups • This is the “best fit” hypothesis based on the data. • Continually tweaked! Domain Eukarya • Contain a membrane-bound nucleus and membrane-bound organelles • Uni and multicellular • Sexual repro common • Huge diversity… • Intro to plant lab… Most Prokaryotes • Ubiquitous • Mostly unicellular • Cocci, bacilli, helices • 1-5 micrometers • Cell wall = peptidoglycan • Capsule • Pili Most Prokaryotes cont. • No nucleus – chromosome = circular • Reproduce asexually • Metabolic diversity • Of significant importance to humans Domain Bacteria • Most diverse and widespread • Most of the known prokaryotes • Every major mode of nutrition and metabolism is represented Domain Archaebacteria • Thought to originate from earliest cells • Extremophiles • Methanogens • Extreme halophiles • Extreme thermophiles Domain Eukarya: Protista • Unicellular eukaryotes + “simple” multicellular relatives • 20+ kingdoms? • Mostly aquatic • Nutritionally diverse • Mostly aerobic • Protozoa, Algae, absorptive Domain Eukarya: Fungi • Multicellular eukaryotes • Saprobes, exoenzymes • Cell wall = chitin • Some are symbiotic • Critical ecosystem value • Commercial value Domain Eukarya: Plantae • Multicellular eukaryotes that carry out photosynthesis • Grouped by adaptations to terrestrial living • Cell wall = cellulose Domain Eukarya: Plantae • Bryophytes: liverworts, hornworts, mosses • Embryos remain attached • Nonvascular Domain Eukarya: Plantae • Seedless Vascular plants: lycophytes, ferns, horsetails, whisk ferns • No seed stage • Require water for reproduction Domain Eukarya: Plantae • Gymnosperm: Ginkgo, cycads, gnetae, conifers • vascular, naked seeds Domain Eukarya: Plantae • Angiosperm: bear seeds within protective chambers • FLOWERING PLANTS Domain Eukarya: Animalia • What is an animal? Domain Eukarya: Animalia • Multicellular eukaryotes that INGEST other organisms • Held together by structural proteins • Have nervous and muscle tissue Domain Eukarya: Animalia • MOST reproduce sexually • Go through stages of embryonic development • Have Hox genes Domain Eukarya: Animalia • Aerobic • Broken into two major groups based on the presence of a backbone • Radial or bilateral symmetry • MOST have Cephalization Pause for activity… • Purpose: – To practice/hone your classification skills… – Experience the real challenges of classification