Why Classify?Why Classify?

• Aids in memoryAids in memory

• Improve our predictive powersImprove our predictive powers

• Improves ability to explain Improves ability to explain relationships among thingsrelationships among things

• Provides a stable and unique name Provides a stable and unique name for organismsfor organisms

Diversity on EarthDiversity on Earth

• Diversity: variety of Diversity: variety of living organismsliving organisms

• Estimated between Estimated between 5-15 million 5-15 million speciesspecies

• Only 1.5 million Only 1.5 million have been have been describeddescribed

The History of ClassificationThe History of Classification

• Earliest known system Earliest known system invented by Aristotle invented by Aristotle (470-399 BC)(470-399 BC)– Classified organisms as Classified organisms as

plant or animalplant or animal– Further classified animals Further classified animals

to their mode of to their mode of transportationtransportation• LandLand

• SeaSea

• AirAir

– Used until early 16Used until early 16thth centurycentury

Linnaeus’s Classification Linnaeus’s Classification SystemSystem

• Swedish botanist (1707-1778)Swedish botanist (1707-1778)

• Binomial Nomenclature – two-part Binomial Nomenclature – two-part scientific name scientific name Genus speciesGenus species

• Why Latin?Why Latin?•Latin was the language known universally by Latin was the language known universally by

the educated the educated

•Also used as a descriptor Also used as a descriptor

King Phillip Comes Over For King Phillip Comes Over For Good Spaghetti Good Spaghetti

• KingdomKingdom

• Phylum Phylum

• ClassClass

• Order Order

• FamilyFamily

• GenusGenus

• SpeciesSpecies

LionLion

Common vs. Scientific Common vs. Scientific NamesNames• Scientific names eliminate confusion Scientific names eliminate confusion

• Binomial nomenclature is the Binomial nomenclature is the universal language for the universal language for the organization of species. organization of species.

• Different areas use different common Different areas use different common names for the same species.names for the same species.

• The same common name is also used The same common name is also used for different species.for different species.

Erithacus rubecula Turdus migratorius

RobinsRobins

Family Petroicidae Leiothrix lutea

Common Names for Common Names for Lutjanus griseusLutjanus griseus

• gray silkgray silk• mangrove snapper mangrove snapper • mangrove pargue mangrove pargue • mango snappermango snapper• parguepargue• black pargueblack pargue• black snapper black snapper • lawyer lawyer • silksilk• snapper snapper

CladisticsCladistics

• Today we try to group organisms Today we try to group organisms based on lines of descent based on based on lines of descent based on shared derived characteristicsshared derived characteristics

• Derived characters are characteristics Derived characters are characteristics that appear in recent ancestry, but not that appear in recent ancestry, but not necessarily in older membersnecessarily in older members

• Cladograms are used to show these Cladograms are used to show these shared derived characters to explain shared derived characters to explain evolutionary relationships.evolutionary relationships.

What We Learned from What We Learned from DarwinDarwin• Principles based on the Principles based on the

theory that there is theory that there is unity in lifeunity in life– All organisms related All organisms related

through descent to some through descent to some unknown prototype in unknown prototype in the pastthe past

– Descendants spilled into Descendants spilled into various habitatsvarious habitats

– Accumulated diverse Accumulated diverse modifications or modifications or adaptations that fit them adaptations that fit them to these habitatsto these habitats

Where do we begin?...Where do we begin?...

• Basic building blocks of life…Basic building blocks of life…– ProkaryoteProkaryote

•““first kernel” – no true nucleusfirst kernel” – no true nucleus

•No membrane-bound organellesNo membrane-bound organelles

•Single cellSingle cell

– EukaryoteEukaryote•True nucleusTrue nucleus

•Membrane-bound organellesMembrane-bound organelles

•Unicellular or multi-cellularUnicellular or multi-cellular

Domain ArchaeaDomain Archaea

• Wasn’t recognized as a Wasn’t recognized as a major domain until major domain until recently recently

• Prokaryotic cells lacking Prokaryotic cells lacking nucleinuclei

• Same basic structures as Same basic structures as EubacteriaEubacteria

• Live in extreme Live in extreme environmentsenvironments– Thermal ventsThermal vents– Hot springsHot springs– Alkaline, saline or acidic Alkaline, saline or acidic

waterswaters– Methane producing clustersMethane producing clusters

Domain EubacteriaDomain Eubacteria

• Monera = BacteriaMonera = Bacteria

• Prokaryotic cells lacking nucleiProkaryotic cells lacking nuclei

• Has many applicationsHas many applications– Cause human diseaseCause human disease– Beneficial symbiosis in plants and Beneficial symbiosis in plants and

animalsanimals– Make up the base of the food webMake up the base of the food web

Domain EukaryaDomain Eukarya

• Make up the majority of the diversity Make up the majority of the diversity of life on Earth – Plantae, Animalia, of life on Earth – Plantae, Animalia, Fungi, ProtistaFungi, Protista

• Eukaryotic cellsEukaryotic cells

Evidence for Common Evidence for Common DescentDescent

Six Kingdom SystemSix Kingdom System

• Six KingdomsSix Kingdoms– EubacteriaEubacteria– ArchaeabacteriaArchaeabacteria– ProtistaProtista– FungiFungi– PlantaePlantae– AnimaliaAnimalia