taxonomy: organizing life’s diversity. “random” facts it is estimated that there are between 3...
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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
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