Principles of Taxonomy (chapter 18, page 446)   Taxonomy is the science of classifying organisms based on their characteristics. Why is a system of classification needed?            a.         Organize species into groups and discuss them.            b.         Identify new organisms.            c.         Show relationships between organisms.  

We use a system of classification developed by Carolus Linnaeus (1707-1778) called the Linnaeus system.

Classification Linnaeus’s System of Classification now includes eight levels: Domain Kingdom Phylum Class Order Family Genus Species

Classification The system is hierarchal. This example is for the species panthera pardus,

Taxonomy     When scientists are referring to organisms they do not have to use all seven levels, just the last two.  This is the way organisms are named in science.     The system of naming organisms using 2 names, the genus and the species, is called the binomial system (also called binomial nomenclature) and was also developed by Linnaeus.     Using the binomial system avoids the confusion caused by organisms with different common names in different areas.

Binomial nomenclature Use the genus (or the first letter of the genus), capitalized, and the species. ex. Castor canadensis or C. canadensis       The species name is not capitalized and cannot be used alone. e.g., C. canadensis.

If you are handwriting the name, underline it. If typing the name, put it in italics.

The 2 part name gives clues about relationships between organisms The 2 part name gives clues about relationships between organisms. (For instance, Ursus americanus, U. horribilis, U. arctos, and U. maritimus are all related.)

Classification based on modern technology Classification used to be based largely on physical appearances but modern taxonomists use genetic information, molecular biology, and phylogeny (evolutionary relationships) as criteria for classifying.  The work of Charles Darwin introduced the idea of considering evolutionary history.

Horse + Donkey = mule or hinnie So, what is a species? Capable of reproducing fertile offspring with one another. (Individuals from different species do not generally reproduce with one another) Horse + Donkey = mule or hinnie Mule + Mule = 0 Individuals within a species may look quite different (Think about the many Canus familiaris)

How many species are there? Estimates on the number of eukaryotic species range from 2 million to 10 million species on the planet although about 1.4 million species (eukaryotic) are currently named and described. It is much more difficult to estimate the number of prokaryotic species, although it is believed that there are many millions (more than eukaryotic).

Kingdoms/domains system pages 457 to 461 Originally there were only two kingdoms recognized by Linnaeus: animals and plants.     

Later, these two were divided into five: animals, plants, fungi, protista, and monera (bacteria). Now, most people, including Bio 112 students, recognize 6 kingdoms and 3 domains.

Now there are 6. Recent research using DNA analysis has shown how groups of organisms are more similar than can be observed by the “naked eye”. Evolution of organisms has been traced, relationships among organisms found. This has been used to place organisms into “domains” (right above Kingdoms).

Cladogram Biologists now group organisms into categories based on lines of evolutionary descent, called phylogeny, not just on physical characteristics. These evolutionary relationships are shown in cladograms. Page 452.

https://www.youtube.com/watch?v=H6IrUUDboZo

3 Domains: bacteria, archaea and eukarya. 6 kingdoms: eubacteria, archae, protista, fungi, plantae, animalia    

Look at the chart on page 459 and read pages 458 to 461. You are required to know which Domain each Kingdom is in and the general characteristics of members of each Kingdom. (See the chart which we will make in class.)