Classification Classification is the arrangement of organisms into

Classification • Classification is the arrangement of organisms into orderly groups based on their similarities • Classification is also known as taxonomy • Taxonomists are scientists that identify & name organisms The Big Picture 1

Benefits of Classifying • Accurately & uniformly names organisms • Prevents misnomers such as starfish & jellyfish that aren't really fish • Uses same language (Latin or some Greek) for all names 2

Classification Groups • Taxon ( taxa-plural) is a category into which related organisms are placed • There is a hierarchy (order from greatest to least) of groups (taxa) from broadest to most specific • Domain, Kingdom, Phylum, Class, Order, Family, Genus, species • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species 3

Domain- Eukarya • Did • King • Phillip • Come • Over • From • Great • Spain? copyright cmassengale 4

Domains • Broadest, most inclusive taxon • Three domains • Archaea and Bacteria are unicellular prokaryotes (no nucleus or membrane -bound organelles) • Eukarya are more complex and have a nucleus and membrane-bound organelles copyright cmassengale 5

The 4 Kingdoms in Eukaryota Protista Plantae Examples: • Amoeba • Algae • Daphnia • Plasmodium (causes malaria) Examples: • Mosses • Ferns • Trees • Flowering Plants Fungi Animalia Examples: • Mushrooms • Athlete’s foot • Bread Mold Examples: • Insects • Spiders • Crabs • Birds • Humans Mostly unicellular and microscopic Autotrophic or heterotrophic Can be infectious agents Multicellular Heterotrophic Decomposers Can be infectious agents Multicellular green plants Autotrophic through photosynthesis Have a cell wall Multicellular Animals Heterotrophic No Cell Wall

Basis for Modern Taxonomy • Homologous structures (same structure, different function) • Similar embryo development • Molecular Similarity in DNA, RNA, or amino acid sequence of Proteins copyright cmassengale 7

• CLADOGRAMS • Cladistics is a system of taxonomy that reconstructs phylogenies by inferring relationships based on similarities. • It is used to determine the sequence in which different groups of organisms evolved. • To do this, it focuses on a set of unique characteristics found in a particular group of organisms. • These unique characteristics are called derived traits or derived characteristics.

• Using patterns of shared derived traits, biologists used cladistics to construct a branching diagram called a cladogram. • A cladogram shows a sequence in which different groups of organisms evolved • The key to Cladistics is identifying structural, physical, genetic, or behavioral traits that differ among the organism being studied and that can be attributed to a common ancestor.

Dichotomous Key • Used to identify organisms • Characteristics given in pairs • Read both characteristics and either go to another set of characteristics OR identify the organism 10

Example of Dichotomous Key • 1 a Tentacles present – Go to 2 • 1 b Tentacles absent – Go to 3 • 2 a Eight Tentacles – Octopus • 2 b More than 8 tentacles – 3 • 3 a Tentacles hang down – go to 4 • 3 b Tentacles upright–Sea Anemone • 4 a Balloon-shaped body–Jellyfish • 4 b Body NOT balloon-shaped - 5 1 2 3 11

• Systematics is a system that organizes the tremendous diversity of organisms into a phylogenetic tree. • A phylogenetic tree is a family tree that’s shows the evolutionary relationships thought to exist between organisms. • It represents a hypothesis that is based on lines of evidence such a the fossil record, morphology, embryological patterns of development, and chromosomes and macromolecules.