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