CLASSIFICATIONWhy do you think scientists like to put organisms into groups, like mammals or insects?

WHAT IS CLASSIFICATION?

Classification is the arrangement of organisms into orderly groups based on their similaritiesClassification is also known as taxonomy

Taxonomists are scientists that identify & name organisms

Taxonomists classify organisms into groups called taxon

WHY CLASSIFY?

Scientists have classified about 2 million speciesHowever, there are many more

organisms than we have found. Estimates usually range from 3-10

million, but go as high as 50 millionThat shows Earth has a tremendous

amount of biodiversity(variety of organisms)

This is only 1-5% of all organisms that have ever lived!!!!!

Sea “horse”??

WHY CLASSIFY?

Accurately & uniformly names organisms Prevents misnomers such as starfish

& jellyfish that aren't really fish Uses same language (Latin or some

Greek) for all names

CONFUSION IN USING DIFFERENT LANGUAGES FOR NAMES

LATIN NAMES ARE UNDERSTOOD BY ALL TAXONOMISTS

EARLY TAXONOMISTS

2000 years ago, Aristotle was the first taxonomistAristotle divided organisms into

plants & animalsHe subdivided them by their habitat

---land, sea, or air dwellers

CAROLUS LINNAEUS: 1707 –1778

18th century taxonomistClassified

organisms by their structure

Developed naming system still used today

CAROLUS LINNAEUS

Called the “Father of Taxonomy”Developed the modern system of naming known as binomial nomenclatureTwo-word naming system

BINOMIAL NOMENCLATURE

Genus speciesLatin or GreekCapitalize

genus, but NOT species

Underline when writing

Italicized in print

American Robin

BINOMIAL NOMENCLATURE

The International Code for Binomial Nomenclature contains the rules for naming organisms

All names must be approved by International Naming Congresses (International Zoological Congress)

This prevents duplicated names Organisms are often named using descriptive

words, like habitat or a physical characteristic OR sometimes using the person whom discovered them

LEVELS OF CLASSIFICATION

The levels of classification are a hierarchy of groups (taxa) from broadest (domain) to most specific (species)

LEVELS OF CLASSIFICATION

Domain Kingdom Phylum Class Order Family Genus Species

Sometimes subspecies is added to the bottom of the list Subspecies

are the same species, but they live in different areas

King Phillip Came Over For Good Soup!

SYSTEMATICS

Systematics is a science whose goal is to classify organisms in terms of their natural relationships Phylogenetics is a type of

systematics

PHYLOGENETICS

The analysis of the evolutionary or ancestral relationships among taxa.

Classification is based on evolutionary relationshipsFound by studying RNA, DNA,

amino acids, homologous structures, and embryos

These relationships are often shown in a cladogram

CLADISTICS

Cladisticsis a type of phylogenetics

A cladogram is a type of phylogenetic diagram

CLADISTICS

Cladogram-A diagram showing how organisms are related based on shared, derived characteristics such as feathers, hair, or scalesShared characters are features that ALL

members of a group have in common. For example, all organisms in the Domain Eukarya domain have true nuclei

Derived characters are features that evolved only in the group under consideration. Feathers for example, are believed to have evolved only in the birds, not from a common ancestor that they have with reptiles.

CLADISTICS

Cladograms are organized into clades, which is an ancestor and all of its descendants.

Cladograms are not only based on physical features, they are also based on biomolecular similarities (like DNA, chromosomes and proteins)

Outgroups-have no shared characteristics with the other organisms in the diagram and are only distantly related

CLADOGRAM

Feathers are a derived characteristic in the birds

Hagfish are the outgroup

Jaws are a shared characteristic between all organisms except the hagfish

CLADOGRAM

Hair is a derived characteristic in leopards (on this cladogram, only leopards have hair) NOTE-hair is a shared characteristic in the

previous cladogram, so these characteristics can change based on the cladogram

Character tables may help you make cladograms

DICHOTOMOUS KEYS

Used to identify organisms"Dichotomous" means "divided

into two parts". Characteristics given in pairsRead both characteristics and

either go to another set of characteristics OR identify the organism

DICHOTOMOUS KEYS

Always read both choices, even if the first seems to be the logical one at first.

Be sure you understand the meaning of the terms involved. Do Not Guess.

When measurements are given, use a calibrated scale. Do Not Guess.

Since living things are always somewhat variable, do not base your conclusion on a single observation. Study several specimens to be sure your specimen is typical.

If the choice is not clear, for whatever reason, try both divisions. If you end up with two possible answers, read descriptions of the two choices to help you decide

DICHOTOMOUS KEYS

1. a. Bean round………..Garbanzo bean

b. Bean elliptical or oblong…..Go to 2

2. a. Bean white…………White northern

b. Bean has dark pigments……Go to 3

3. a. Bean solid in color…….Go to 4

b. Bean is spotted……..….Pinto bean

4. a. Bean black…………........Black bean

b. Bean reddish-brown…….Kidney bean

MAKING DICHOTOMOUS KEYS

Eliminate an organism in every step (one part leads to a name, the other part leads to another step)

Use measurements rather than terms like "large" and "small".

Try to make the choice a positive one -something "is" instead of "is not".

MAKING DICHOTOMOUS KEYS - CONTINUED

If possible, start both choices of a pair with the same word.

If possible, start different pairs of choices with different words.

Precede the descriptive terms with the name of the part to which they apply.(like legs are red instead of red legs)

DICHOTOMOUS KEY ASSIGNMENT

You will be creating your own dichotomous key

The subjects of the key will be all the people in your row of desks

Criteria must be high school appropriate and non-insulting

Everyone should have between 7 – 10 people