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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.
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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
John Ray, 1600’s: • “When men do not know the name and properties of natural objects – they cannot see and record accurately.”
1700’s • Carl von Linne = Linnaeus • Father of Taxonomy • Systema Naturae
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 Bufoamericanus Mustellavison Escherichia coli Canus lupus Turdus migratorius Binomial Naming System
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.
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
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:
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…
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…
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