SB3c: Examine evolutionary basis of modern Classification.

Jabberwock

Why do we classify living things? We have about 1.5 million NAMED & classified species. There may be over 30 million species on Earth!! We organize so we can communicate, share information & find information.

Taxonomy …branch of biology for naming & grouping of organisms Organisms can be grouped according to: their characteristics their evolutionary history

A Brief History of Taxonomy Aristotle – had 2 groups, plants & animals Linnaeus – developed a Hierarchy of levels, according to morphology (physical appearance)

Problems with using morphology to classify Some things may look different but still be a member of the same species. Injuries or other events may alter the physical appearance Some things look alike but are not related (dolphins & fish)

How closely are these beetles related?

Hierarchy of taxonomy

Binomial Nomenclature …is the ”2 part scientific name” of an organism RULES 1) 1st word = genus name, always capitalize 1st letter 2) 2nd word = species name, all lower case 3) italicized or underlined 4) Written in Latin

Binomial Nomenclature Example Homo sapien = humans Hyla squirella= squirrel treefrog P. leo = lion

Phylogeny ...classifying organisms according to their evolutionary history A phylogenetic tree can be created using systematics (aka, taxonomy.)

How does systematics work? Use evidence from many sources: 1) fossils 2) morphology (physical appearance) 3) embryological development 4) chromosomes & DNA

Cladograms …branching diagrams that show the evolutionary history between organisms. Systematics uses derived characters to make cladograms The more derived characters an organism shares the more closely related they are.