Classification of Organisms

Section 1: Categories of Biological Classification

Section 2: How Biologists Classify Organisms

Categories of Biological Classification

Objectives:•Describe Linnaeus's role in developing the modern system of naming organisms.•Summarize the scientific system for naming a species.•List the seven levels of biological classification.

Categories of Biological Classification

Taxonomy•A Simpler System Swedish biologist Carl Linnaeus developed binomial nomenclature, the two-word system of naming organisms. •Scientific Names Scientific names are written in Latin and give biologists a common way of communicating, regardless of the language they speak. The scientific name of an organism consists of its genus name followed by a second name, which identifies its species.

Scientific Names

Common Name Human Dog Cat Tiger Jaguar Leopard Crayfish

Genus, Species Homo sapiens Canis familiaris Felis catus Felis pardina Panthara tigrus Panthara pardus Cambarus zophonaetes

Scientific Names

Common Name Human Dog Cat Tiger Jaguar Leopard Crayfish

Genus, Species Homo sapiens Canis familiaris Felis catus Felis pardina Panthara tigrus Panthara pardus Cambarus zophonaetes

Scientific Name Rules:

1. Genus name capitalized 3. Underlined (or italic)

2. 2nd name lower case

ASSIGNMENT

Each group will be given a list of 6 related organisms.

Using the internet, determine the scientific name of each organism and write in your paper

Find a detailed picture of each organism. Type their common and scientific name after the picture

Print off one copy for each group member.

Sample Dichotomous Key

1a.Bean round Garbanzo bean

1b.Bean elliptical or oblong Go to 2   

2a.Bean white White northern

2b.Bean has dark pigments Go to 3   

3a.Bean evenly pigmented Go to 4

3b.Bean pigments mottled Pinto bean   

4a.Bean black Black bean

4b.Bean reddish-brown Kidney bean

Dichotomous Key Rules of Thumb

Start with the most general characteristics and progress to increasingly more specific characteristics.

Indent each couplet or leave a space between each couplet to make the key easier to read.

Use measurements when possible, avoiding descriptors like large or small if possible.

Use characteristics that are found year-round, not seasonal if at all possible (sometimes the point of a key is identifying organisms based on seasonal characteristics, such as flowers). If your key is seasonal, indicate it in the title of the key. 

Start the choices in the pair with the same word , if possible.

Dichotomous Key Assignment

Find high quality pictures of your organisms online (Google-images) and cut and paste them into a word document. Place the organisms scientific name and common name underneath

Design a dichotomous key that corresponds to the organisms.

Dichotomous Classification Key

Has a key which presents the user with two opposite categories about a trait.

This leads the user to further pairs of statements.

By going from one set of statements to another its classification group is determined.

Categories of Biological Classification

Classifying Organisms

•Categories of Classification The modern system of classification includes the following eight groups: domain, kingdom, phylum, class, order, family, genus, and species.

Section 1

Categories of Biological Classification

•Classification of the Honeybee Each category of classification is based on characteristics that are shared by all the organisms in the category. The European honeybee is classified as: Eukarya, Animalia, Arthropoda, Insecta, Hymenoptera, Apidae, Apis, and mellifera.

How Biologists Classify Organisms

Objectives:•List the characteristics that biologists use to classify organisms.•Summarize the biological species concept.•Relate analagous structures to convergent evolution.•Describe how biologists use cladograms to determine evolutionary histories.

How Biologists Classify Organisms

What is a Species?•Species Species were traditionally defined according to their appearance and structure.•Biological Species The biological species concept defines species according to their sexual reproductive potential.

How Biologists Classify Organisms

What is a Species? continued•Evaluating the Biological Species Concept The biological species concept cannot be used to classify asexually reproducing species.•Number of Species The number of the species in the world is much greater than the number described.

How Biologists Classify Organisms

History•Cladistics Cladistics focuses on sets of unique or derived characteristics found in a particular group of organisms to reconstruct an evolutionary history.