What is the purpose of the Classifying System?

To allow the accurate identification of a particular organism

Taxonomy The practice of classifying organisms

-Taxonomy was founded nearly 300 years ago by a Swedish botanist named Carolus Linnaeous

** Biologists still use Linnaeous’ method of naming each species using two Latin names called BINOMIAL NOMENCLATURE

Example: Felis domestiscus

What animal is this??

Hierarchy of Groups

There are different degrees of similarities among animals.

Eg. A horse is more like a turtle than it is a fish

To distinguish different degrees of similarities,

each Kingdom is subdivided several times into

as series of progressively smaller groups.

Each group is called a TAXON

Kingdoms are the largest and most general taxa

Species include only a single type of organism

Hierarchy of GroupsKINGDOM

PHYLUM

CLASS

ORDER

FAMILY

GENUS

SPECIES

As you move down the taxa, each taxon contains fewer species and becomes more specified.

(The smaller the taxon, the more similar the organisms are within it)

Table 4.1

Binomial Nomenclature

Ex. Lynx canadensis

The first name = genus name (capitalized)

The second name = species name (small caps)

The complete name is italicized or underlined.

How Biologists Classify Organisms Scientists use several types of evidence to classify

organisms. We will look at 5 types of evidence.

1. Evidence from the fossil record

Use decay of unstable carbon isotopes (radioactive) in a process called radiocarbon dating to determine ages of fossils Eg. Archaeopteryx (pg. 113)

2. Evidence from Anatomy

Arrangement and similarities of bone structures may indicate organisms with similar evolutionary origin.

E.g. Bone Structure (figure 4.9 pg 114)

3. Evidence from Embryonic Development

Comparisons of early stages of embryonic development can reveal relationships between species that may not look alike in the adult stage. (Figure 4.10)

4. Evidence from biochemistry

Comparisons of protein molecules among organisms can indicate genetic differences and similarities.

5. Evidence from DNA

Helps to determine how long ago two species began to diverge from a common ancestor

- Human DNA matches closely to other primates

93% with monkeys

98% with chimpanzees

PhylogenyPhylogeny – the evolutionary history of a kind of organism

Phylogenic Tree (Figure 4.14)

- resembles a family tree

- represents the evolutionary relationships among groups of organisms

Phylogenetic Tree- Base represents the oldest ancestor (or

Kingdom)

- Upper ends represent the present day descendant species.

- Forks represent points when an ancestral species split into a new species

CladisticsCladistics - a classification scheme based on phylogeny

Based on the idea that each group of related species has one common ancestor.

Some animals retain ancestral characteristics, others gain evolved characteristics

Cladogram

- a branching diagram that resembles a phylogenic tree

- can be used to determine relationships between species (Figure 4.17)

Section 4.2 Review Questions

Page 121 #’s 1-3, 5-7, 10, 12

Section 4.2 Answers1. List two reasons why the system of binomial

nomenclature is useful.

It identifies organisms precisely and allows scientists from different areas in the world to communicate about the same species.

2. Cats, goldfish and humans are in the same phylum. What characteristics do they have in common? What characteristics place cats and humans in a different order from goldfish?

All organisms have a backbone and are in the subphylum Vertebrata.

Cat and human are mammals with warm blood, body hair and young born alive.

Fish are aquatic, covered in scales and are egg-laying.

3. Based on your own knowledge, place the following species into three different phyla: ant, crow, spider, turtle, salmon, snail, octopus.

Crow, turtle, salmon = Chordata

Ant, spider = Arthropoda

Snail, octopus = Mollusca

5. Referring to the table shown here, which two animals are most closely related? Explain your answer.

The dog and coyote

- they share the highest number of common taxa

- only the species names are different

6. The information in this table shows that a skunk is more closely related to a coyote than it is to a bat. Explain how you know this.

The skunk and coyote are in the same order, so are more closely related to each other than either is to a bat.

7. What kind of animal is Myotis myotis? How do you know? Use the table shown here to help you.

It is a bat since it belongs to the bat genus (myotis = Latin for bat).

The species name indicates that the bat is not a brown bat but another species of bat.

10. Outline the kinds of information biologists use to classify organisms. Which do you think is the most helpful or important? Why?

Fossil record, anatomy, embryonic development, biochemistry, DNA, phylogeny….

(Provide a reasonable explanation for the one you feel is more helpful/important.)

12. Describe the relationships in the following phylogeny diagram. Which two species are most closely related? Explain your answer.

Fish Q and R are most closely related because they diverged the latest.