Classification

ClassificationWhy do we classify things? Finding Order in Diversity

Classification provides scientists and students a way to sort and group organisms for easier study.

Taxonomy – branch of biology that deals with the classification and naming of living things

There are millions of organisms on the earth! (approximately 1.5 million have been already named)

ClassificationClassifying and Naming Organisms

1. Grouping organisms based on comparing characteristics makes it easer to study the diversity of live.

2. Binomial Nomenclature – 2 word system of identifying each kind of organism; avoids confusion

A. Carolus Linnaeus – founder of modern taxonomy; used structural similarities as a basis for his classification system

Classification

Carolus Linnaeus

Why do biologists consider Linnaeus’s system an improvement over earlier systems?

Classification

Classification

ClassificationClassifying and Naming Organisms

1. Binomial Nomenclature (cont.)B. Scientific Name – both names

togetheri. 1st name – genus (always

capitalized) ii. 2nd name – identifies species

within the genus (lower case) iii. Name is written in italics or underlined

ClassificationLinnaeus’s Classification System – hierarchical system from most inclusive to least inclusive are:

ClassificationThis illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category.

ClassificationGo to Fig. 18-4

What do the scientific names of the polar and grizzly bears tell you about their similarity to each other?

Modern Evolutionary ClassificationLinnaeus’s system was limited because similarities and differences were mainly visible

What was invented that helped to change the way scientists classify organisms?

Modern Evolutionary ClassificationEvolutionary classification based on

Darwin’sTheory of Evolution – Decent with

ModificationSpecies gradually change, or evolve, over

time frompre-existing species

Modern Evolutionary ClassificationClassifying species based on easily

observed adult traits can pose problems. Which of these organisms seem most alike?

Modern Evolutionary ClassificationCladograms – a diagram that shows

evolutionary relationships among organisms based on shared derived characters (Fig. 18-7)

Ways is which taxonomists classifyStructural – ex. Skeletal structure, leaf

anatomy

Ways is which taxonomists classifyStructural – ex. Skeletal structure, leaf

anatomy

Ways is which taxonomists classifyBehavioral – similar behaviors may

indicate a close relationship – Fig. 18-8

American and African vultures look very much alike and were once classified together. American vultures have a peculiar behavior: When they get overheated, they urinate on their legs to cool down. The stork is the only other bird known to behave this way.

Ways is which taxonomists classifyBiochemical – information about DNA,

RNA & proteins can be used to help determine relationships and can be used to estimate how long different species have been separatedAfrican Vulture American Vulture Wood Stork

Ways is which taxonomists classifyCytological – cellular structure – ex.

Prokaryotic vs. eukaryotic, plant cell vs. animal cell

Ways is which taxonomists classifyEmbryological – early stages of

development may show shared characteristics that are absent at the adult stages (Fig. 15-17 pg. 385)

Ways is which taxonomists classifyFossil Formation – establish relationships

between modern-day species & those that lived years ago