Classification of Living Things http://analyzer.depaul.edu/astrobiology/kingdoms.jpg

Taxonomy Branch of biology that names and groups organisms according to their characteristics and evolutionary history. Does it have Legs? Feathers? Scales? What did it look like before? What can you compare it to?

History The first person to group or classify organisms was the Greek teacher & philosopher ARISTOTLE. (300 B.C.)

Based on where they lived Aristotle’s System PLANTS: ANIMALS: Based on size of stem Based on where they lived

Problems? Not all organisms fit into Aristotle’s 2 groups (plants or animals) Ex: What about? Bacteria Fungi

Problems? 2. Common names can be misleading Ex: A jelly fish isn’t a fish, but a seahorse is! Sea cucumber sounds like a plant but… it’s an animal!

Problems? 3. Common names vary from place to place. Ex: puma, catamount, mountain lion, cougar are all names for same animal

Problems? 4. Same organisms have different names in different countries. Chipmunk Streifenhornchen (German) Tamia (Italian) Ardilla listada (Spanish)

Quercus foliis obtuse-sinuatis setaceo-mucronatis SOLUTION? Some early scientists devised scientific names using long descriptions in LATIN. Example: Red Oak Quercus foliis obtuse-sinuatis setaceo-mucronatis “oak with leaves with deep blunt lobes bearing hair-like bristles”

Problems Names too hard and long to remember! Names don’t show relationships between different animals!

Carolus Linnaeus To The Rescue! Devised a new classification system based on MORPHOLOGY (Organism’s form and structure) (1707-1778)

Linnaeus’s System Grouped in a HIERARCHY of 7 different levels Each organism has a two part LATIN SCIENTIFIC NAME

Kingdom Phylum Class Order Family Genus Species Kids Prefer Cookies Over Fried Green Spinach

Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Carnivora Felidae Panthera leo

BINOMIAL NOMENCLATURE (2 name naming system) 1st name = GENUS NAME Always capitalized 2nd name = SPECIES IDENTIFIER Always lower case Both names are UNDERLINED or written in ITALICS

Binomial Nomenclature Vampire bat Desmodus rotundus Eastern chipmunk Tamias striatus

Binomial Nomenclature Humans Homo sapiens or

SPECIES “Species are groups of actually or potentially interbreeding populations, which are reproductively isolated from other such groups.” Reproductively isolated group Ernst Mayr

DIFFERENT SPECIES

Remember: Linnaeus only had 2, plant and animal So What Do We Use Now? MODERN TAXONOMY Still use Linnaeus’s system: but we have added more KINGDOMS Remember: Linnaeus only had 2, plant and animal

The Kingdoms Archaebacteria Eubacteria Protist Fungi Plantae Animalia

The Phyla We’re Studying Porifera (sponges) Cnidaria (jellyfish and corals) Nemotode (roundworms) Platyhelminthes (flatworms) Molluska (clams, squid, octopi) Annelids (earthworms) Arthropods (crabs, insects, spiders) Echinoderms (starfish, urchin) Chordates (vertebrates)

MODERN TAXONOMY

Modern Taxonomy

MODERN TAXONOMY Organizes living things in the context of evolution

MODERN TAXONOMY Scientists use different kinds of info to classify organisms: Fossil record Morphology Embryology Chromosomes Macromolecules (DNA & proteins)

FOSSIL RECORD We can trace some changes over time through the fossil record. Evolutionary history = PHYLOGENY

MORPHOLOGY Shape and Function

MORPHOLOGY HOMOLOGOUS characteristics: same embryological origin (may have similar structure and function) EX: Bat wing & human arm Homologous characteristics suggest a recent common ancestor

MORPHOLOGY ANALOGOUS characteristics: may have similar structure & function but different embryological origin EX: Bird wing & butterfly wing ANALOGOUS characteristics evolved separately. Organisms NOT CLOSELY RELATED

ANALOGOUS STRUCTURES Bird wing and butterfly wing have evolved with similar function BUT different structure inside. Insects and birds NOT closely related!

EMBRYOLOGY Animals whose embryos develop in a similar pattern may be related

CHROMOSOMES Similar karyotypes suggest closer relationships.

46 individual chromosomes 48 individual chromosomes 4 individual chromosomes

MACROMOLECULES Compare molecules like PROTEINS (amino acids) DNA Organisms with similar sequences are probably more closely related.

Terminology Classification Assigning organisms to different categories based on their relationship Taxonomy The science of naming organisms Systematics Determining evolutionary relationships of organisms Phylogeny Evolutionary history