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Ch Ch 17:Classification17:Classification

Modified from Massengale, biology junction

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What is Classification?What is Classification?

•ClassificationClassification is the is the arrangement of organisms arrangement of organisms into orderly into orderly groupsgroups based based on their on their similar similar characteristics.characteristics.

•Classification is also known Classification is also known as as taxonomy.taxonomy.

•Taxonomists Taxonomists are scientists are scientists that identify & name that identify & name organisms.organisms.

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Benefits of ClassifyingBenefits of Classifying

•Make sense and order of things.

•Accurately Accurately && uniformly uniformly names organisms. names organisms.

•Prevents Prevents misnomersmisnomers such such as starfish & jellyfish that as starfish & jellyfish that aren't really fish. aren't really fish.

•Uses Uses same language same language (Latin or some Greek) for (Latin or some Greek) for all names.all names.

Sea”horseSea”horse”??”??

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Early TaxonomistsEarly Taxonomists•2000 years ago, 2000 years ago, AristotleAristotle was the first was the first taxonomist.taxonomist.

•Aristotle divided Aristotle divided organisms into 2 organisms into 2 groups - groups - plants plants && animals.animals.

•More organisms were discovered and did not fit into either groups.

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Carolus LinnaeusCarolus Linnaeus1707 – 17781707 – 1778

•18th century taxonomist.

•Classified organisms by their structure.

•Developed naming system still used today.

•An eight-level system based on shared characteristics.

•Hypothesize how closely related organisms are.

•More shared characteristics = more closely related.

The Linnaean System of Classification•Levels (also known as a taxon) of Classification

1. Domain largest taxon.2. Kingdom broken into smaller groups called

PHYLA.3. Phyla/Phylum broken into smaller groups

called CLASS.4. Class broken into smaller groups called

ORDER.5. Order broken into smaller groups called

FAMILIES.6. Families broken into smaller groups called

GENUS.7. Genus are sorted into individual SPECIES.8. Species – the smallest taxon and most

specific.

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Hierarchy-Taxonomic Hierarchy-Taxonomic GroupsGroups

DomainKingdom

Phylum Class

Order Family

Genus Species

BROADEST BROADEST TAXONTAXON

Most Specific

Linnaeus’ classification system has seven levels.

Each level or taxon is included in the level above it.

Levels get increasingly specific from kingdom to species.

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DomainsDomains

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Carolus LinnaeusCarolus Linnaeus•Called the Called the “Father of Taxonomy”.“Father of Taxonomy”.

•Developed the modern system of Developed the modern system of naming known as naming known as binomial binomial nomenclature.nomenclature.

•He developed a He developed a Two-wordTwo-word naming naming system (Genus & species) for an system (Genus & species) for an organism known as organism known as binomial binomial nomenclaturenomenclature..

•Also known as a Also known as a Scientific NameScientific Name..

•Help scientist communicate clearly about living things.

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Standardized Standardized NamingNaming•Scientific names pScientific names provide

consistency amongst scientist when speaking of a specific organism.

•Scientific name is unique to that specific organism.

•Binomial nomenclature uses:Binomial nomenclature uses:

•Genus Genus andand species species

•LatinLatin oror GreekGreek

•ItalicizedItalicized in printin print

•Capitalize genusCapitalize genus, , but NOT but NOT speciesspecies

Turdus Turdus migratoriusmigratorius

American American RobinRobin

Scientific names help scientists to communicate.

–Some species have very similar common names.

–Some species have many common names.

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Section 2: CladisticsDefinition: Classification based on evolutionary relationships.Cladogram: a diagram that shows how species might be related based on derived characteristics such as feathers, hair, or scales.•Derived characteristics - traits that some have and others don’t. Represented on cladogram as hash marks.

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•A clade is a group of species that shares a common ancestor.

•Each species in a clade shares some traits with the ancestor.

•Each species in a clade has traits that have changed.

•Species placed in order that they descended from common ancestor.

Section 2: Cladistics

FOUR LIMBS WITH DIGITS

•Nodes represent the most recent common ancestor of a clade.•Clades can be identified by snipping a branch under a node.

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF THE SKULL

SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW

FEATHERS AND TOOTHLESS BEAKS.

SKULL OPENINGS BEHIND THE EYE

NODE

DERIVED CHARACTER

CLADE

Section 2: Cladistics

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Primate Primate CladogramCladogram