Chapter 14- Classification of Organisms million organisms on Earth!!!! How to organize them? – Assign a single universal name to each organism. – Place organisms into groups that have a real biological meaning. Taxonomy-The science of naming and classifying organisms. This is a universal system. – How did they start? 2,000 years ago Aristotle grouped plants and animals according to structural similarities. – Mid 1700’s-Scientist added descriptive phrases to name the genus. – 1750’s-Charles Linnaeus used a polynomial system. Used a two-word name for each species.

Binomial nomenclature-Two-word system for naming organisms. Latin or Greek. Examples-Turdus migratorius Pica Pica Alces alces

More examples Staphylococcus aureus- clarkia lewisii- Ursus horribilis

Scientific name-Two part name for a species. Genus-A taxonomic category containing similar species. – Organism in a genus share important characteristics. Let’s look at page 301 for examples. All of the above are in the genus ursus.

Classifying Organisms Linnaeus worked out broad system of classification for plants and animals. Its goes like this – Domain-kingdom-phylum-class-order-family- genus-species. – Did King Philip Come Over For Grandma’s Soup?

Classifications

Section 2-How Biologist Classify Organisms Biological Species-A group of natural populations that are interbreeding or that could interbreed, and that are reproductively isolated from other such groups. – Example-domesticated dogs and wolves Phylogeny-Evolutionary history of organism Convergent evolution-Similarities evolved in organisms not closely related to one another. Analogous characters-Similarities that arise through convergent evolution.

Cladistics-Reconstructs phylogenies by inferring relationships based on shared characters. Ancestral character-If a species evolved in a common ancestor of both groups. – Comparing birds and mammals, a backbone is an ancestral character. Derived character-An organism evolved in an ancestor of one group but not the others. – Feathers in birds, but not mammals.

Phylogenic tree of life

Cladistic phylogenetic tree

Ancestral characters

Derived characters

Worksheet due tomorrow Small test on Thursday!! Do not worry, it will be easy and over the notes and lecture.