Systematics, Taxonomy, Classification

Systematics The branch of biology that involves classifying living things, both current and prehistoric. It has 3 components: Taxonomy Classification Phylogenetics

Taxonomy Naming and grouping of diverse forms of life

Classification Organizing information about organisms on the basis of the degree of similarity between them (molecular, phenotypic, anatomical). Phenetics classifies organisms using morphological similarities and relatedness, but does not relate fully to evolutionary relationships among organisms.

Phylogenetics Uses diagrams known as cladograms help to determine evolutionary history and relationships among various forms of life through time.

Taxonomy Aristotle ( BC) Created the first widely used classification system by dividing all organisms into two groups: plants and animals

Carolus Linnaeus ( ) Developed the hierarchical categorization system (kingdom, phylum, class, order, family, genus, species). He developed this system to bring universality to the people who studied science. That way, no matter where you lived, a species with the same characteristics would also have the same name.

Example: Depending on which part of North America you lived in this organism was known as: puma, panther, catamount, Pontiac, cougar, or mountain lion. To reduce the confusion Linnaeus named it Felis concolor

Binomial Nomenclature In this system, each organism gets two names: a genus name and a species name Used Latin for 2 reasons: – It was spoken by educated people – It was a dead language

Ursus maritimus Ursus arctos horribilis polar bear Grizzly bear

Rules of Binomial Nomenclature 1. Each organism gets two names, a genus name and a species name – 1 st letter of the genus name is ALWAYS capitalized – 1 st letter of the species name is NEVER capitalized – A third subspecies name is sometimes added to distinguish between very closely related organisms – Ex. Homo sapiens sapiens – you!

2. If two organisms have the same genus name they are said to be closely related – Canis lupus – wolf – Canis latrans – coyote – Canis lupus familiaris – dog – Vulpes fulva – Red fox

If two organisms have the same species name, but different genus names, they are not closely related. Antlocapra americana – pronghorn antelope Grus americana - whooping crane

Classification Hierarchy Taxonomists also use a larger system to describe organisms more exactly. All life is initially divided into three domains.

1. Domain Archea Simple prokaryotes which are chemosynthetic. Probably represent the most ancient life on Earth.

2. Domain Bacteria Complex prokaryotes (single celled) which are chemosynthetic, hetertrophic or photosynthetic. These include bacteria and blue-green algae.

3. Domain Eukaryota Consists of all life with eukaryotic cells. 4 kingdoms: – Kingdom Protista – organisms with cells which have both plant and animal characteristics – Kingdom Fungi – molds, yeasts, mushrooms – Kingdom Plantae – organisms with plant cells – Kingdom Animalia – organisms with animal cells

Carl Woese Until 1990 when he proposed the Domain system, all life was divided into 5 kingdoms: Animalia, Plantae, Fungi, Protista and Monera (which shared eubacteria and archeabacteria)

Viruses Lack cellular structure and life processes and are therefore given their own group called viruses

Humans! DomainEukaryota KingdomAnimalia PhylumChordata ClassMammalia OrderPrimata FamilyHominidae GenusHomo SpeciesSapiens Sub-speciessapiens

54