Classification of Earth’s Diversity

Biodiversity

• Biodiversity – the variety of organisms on earth is the result of 3.5 billion years of evolution

• Approx 8 million species on earth!• To make sense of all of them, they are

organized into meaningful groups• Species are becoming extinct at an

increasing rate, so there is a rush to catalog them

Common vs Scientific Names• Common names are convenient, but there

are problems: - same names are used for different species (robin here, robin Europe)- can be more than one name for same species (mt lion, cougar, puma)- very ambiguous (not very descriptive)

Common vs. Scientific Names

• Advantages of scientific names:– Provide a consistent naming system for

all– Show evolutionary relationships – Systematics – the science of naming and

grouping organisms according to biological meaning

– Groups are called taxa (singular: taxon)

Binomial Nomenclature• Bi = two, nomial = name• Scientific names have two parts• Always typed in italics (or underlined)• First word is capitalized, second is not• First word - genus – a group of similar

species• Second word - species – unique to

ONLY that species

• Ursus arctos

• Ursus americanus

• Ursus maritimus

• Ursus thibetanus

Brown bearBlack bear

Polar bear Asian black bear

Use Latin language

Linnaean Classification

• Carolus Linnaeus developed 1st system• Four levels of hierarchy, or ranks• Today there are 7: Kingdom, Phylum,

Class, Order, Family, Genus, Species• Bears belong in the Family Ursidae • Pandas are also in this Family, but have

a different genus (Ailuropoda)

• Mnemonic for remembering• King Phyl Came Over For

Good Spaghetti

Kingdom- Ex: p.514

• Largest and most inclusive taxon

• All multicellular animals are in the kingdom Animalia

Phylum• Contains groups of organisms that are

different but share important characteristics• Phylum Chordata features organisms with a

nerve cord along the back• Within the phylum, are groups called

Classes…

Class• Classes are groups that narrow down the

differences even further• Class Mammalia includes all animals that are

warm-blooded, have body hair, and produce milk for their young

• Within a class are groups called orders…

Order• Order Artiodactyla contains hoofed

animals with an even number of toes• Within an order are groups called Families

Family• Family – a group of several genera (plural of genus) that share similarities

• Bactrian camel and dromedary more closely related than the llama (Family Camelidae)

Genus species

• Camelus bactrianus – two humps

• Camelus dromedarius – one hump

• The genus Camelus includes both of these species

Identifying Organisms• Dichotomous keys• Used to VISUALLY identify organisms• Has series of “couplets” or paired statements

that describe visual traits (color, size, unique features, etc.)

• Each statement describes the presence or absence of a visible trait

• Each set of choices helps to narrow down the identity of the organism

NOT like these

• The most useful tool for such identifications is the dichotomous key, which contains information useful in identifying similar kinds of organisms, but is arranged in a way that allows the information to be used quickly.

• A dichotomous key is a list of paired statements (each statement is called a lead) that guides you to the identification of a specimen.

• The paired leads (the pair of leads together is called a couplet) are contrasting descriptions of certain characteristics.

• In a good key, couplets are written so that you must choose one or the other of the leads as being true for your specimen. Couplet leads should always be mutually exclusive

• In addition, the leads in a couplet should be parallel; that is, both should ask questions about the same character(s).

DIRECTIONS:

Can you figure out the key?

• Help! Scientists have discovered quite a few new creatures on planet Pamishan. They need your help to identify and classify them. Use the dichotomous key on the next page to identify these creatures.

• ALWAYS start with step 1, and go to whichever step the key tells you