Classification The organization of living things

Kingdoms

Eubacteria

Archaebacteria

Protista

Plantae

Fungi

Animalia

DOMAIN EUKARYA

DOMAIN ARCHAEA

DOMAIN BACTERIA

Taxonomy• Taxonomy is the system scientist use to name

organisms & put living things into groups

• Organisms are grouped by how closely related they are.

Binomial nomenclature

• Each organism is given a unique scientific name

• The name has 2 parts: genus species

• The genus is always capitalized and the species is not, both are either underlined or in italics – E.g.: Usrus arctor – the grizzly bear

why do you think this naming system was developed?

Hierarchical system of classification

• There are 8 levels of organization

• The largest level, Domain is the most inclusive – Domain, kingdom,

phylum/division, class, order, family, genus, species

Grizzly bear Black bear Giant panda

Red fox Abert squirrel

Coral snake

Sea star

KINGDOM Animalia

PHYLUM Chordata

CLASS Mammalia

ORDER Carnivora

FAMILY Ursidae

GENUS Ursus

SPECIES Ursus arctos

Classification of Ursus arctos

What criteria do you think was used to narrow down each category?

CLASSIFICATION BASED ON VISIBLE

SIMILARITIES

CLADOGRAM

Appendages Conical Shells

Crab Barnacle Limpet Crab Barnacle Limpet

Crustaceans Gastropod

Molted exoskeleton

Segmentation

Tiny free-swimming larva

• Living things are groups by their line of evolutionary descent.

• A picture called a cladogram is used to show how organisms are related and what characteristics separate different groups

Phylogeny Read this cladogram from the bottom up. The traits shown apply to everything above it. Each branch represents a different linage. The lowest line represents a common ancestor.

Macromolecules & classification • In the past biologist

could only look at physical & behavioral characteristics to classify organisms

• Now we can use: RNA, DNA (nuclear & mitochondrial) and proteins

• The more genes organisms have in common the more closely related they are

Which sets of mammals are the most closely related?

Those the top two animals look alike they are not closely related.

Molecular Clock• By comparing differences in amino acid sequences in

the same protein found in different species scientist can figure out how long ago they diverged from a common ancestor (DNA & RNA can also be used)

To paraphrase

As you know radiometric dating is very helpful in determining the age of fossils. We can also use the rate of genetic mutations to construct a molecular clock that can give us information about how long ago two

linages diverged. As you saw with the amino acid lab, species that are more closely related have more similarities in their DNA.

Summary Review1. What is the classification of living things called?

2. What is it called when biologist group things by evolutionary lines?

3. What is a drawing of the evolutionary tree?

Examine this chart and cladogram. You should be able to construct your own cladogram using a similar type of chart.