Transcript Taxonomy - Rocky View Schools

Taxonomy
The science of naming
organisms.
Aristotle
2000 years ago – only 1000 or so
organisms had been “discovered”
 Classification system developed by
Aristotle consisted of:
PLANT
ANIMAL
- woody stems
- motile (move)
- non-woody stems
- sessile (can’t

move)
What are the
levels of
biological
organization?
Biotic
OR
Abiotic?
Carolus Linnaeus
Described organisms with two word names
– all in Latin (why?)
 Developed binomial nomenclature
 First word = genus name (upper case)
 Second word = species name (lower case)

Why binomial nomenclature?
Much easier than a 10+ word name
under old “polynomial system”
 Same name no matter where you go
 Less confusion – same language
throughout the world (Latin)
 Binomial = SCIENTIFIC NAME

Do you know what these animals are?
Homo sapiens  Canis lupus –
 Canis lantrans  Felis domesticus  Pan troglodytes –
 Ursus arctos –
 Equus caballus Turdus migratorius –
 Orcinus orca 
Do you know what these animals are?
Homo sapiens - human
 Canis lupus – wolf
 Canis lantrans - coyote
 Felis domesticus - house cat
 Pan troglodytes – chimpanzee
 Ursus arctos – grizzly bear
 Equus caballus- horse
 Turdus migratorius - robin
 Orcinus orca - killer whale

Taxonomic hierarchy

Names organisms and their
relationships from very broad (ie
includes a lot of organisms in a variety
of categories) to very specific (ie
includes much fewer organisms with
fewer diversifying traits)
All organisms classified in a hierarchy
Domain (broadest)
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species (most specific)

Danish King Phillip Came Over For Green Spinach
3 domains of
life
EUKARYA
BACTERIA
ARCHAEA
Classify a human and a bobcat:
GROUP
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
HUMAN
eukarya
animalia
chordata
mammalia
primates
hominidae
Homo
sapien
BOBCAT
eukarya
animalia
chordata
mammalia
carnivora
felidae
Lynx
rufus
What is a species anyway?

Biological species concept
– A group of actually or potentially breeding
natural groups that are reproductively
isolated from other groups.
» Ernst Mayr, 1924

Extended definition of species to include:
– Hybrids
• Sterile offspring of two different species
How many are out there?

Scientists currently estimate that
– There are 10 million species worldwide
– Over 5 million live in the tropics
– Most unnamed species are small or
microscopic
Why is taxonomy useful?
Helps prevent confusion among
scientists
 Helps to show how organisms are
related
 Can be used to reconstruct
phylogenies – evolutionary histories –
of an organism or group

A note on cladograms
Graph showing when different groups
diverged from a common ancestral line
 Points where they diverge are often
noted with a feature that was different
between ancestral group and a “new”
feature in the group that split off.

Bird Cladogram
Dichotomous Key
• A dichotomous key is a device that can be used to easily
identify an unknown organism.
• The word dichotomous comes from two Greek words that
together mean, "divided in two parts".
• A dichotomous key consists of a series of two part statements
that describe characteristic of organisms. At each step of a
dichotomous key the user is presented with two choices. As the
user makes a choice about a particular characteristic of an
organism they are led to a new branch of the key. Eventually
the user will be led to the name of the organism that they are
trying to identify.
Saskatchewan Education. (1992) Science: A Curriculum Guide for the Secondary Level
Biology 20/30. Saskatchewan Education. p. 106
For example: Construct a dichotomous key
with a few school supply items:
When constructing a dichotomous key, the first step is to
look at the group of objects or organisms and separate
them into two groups based on a single distinguishing
characteristic.
Then continue to separate each of the groups until each
object has its own separate set of characteristics.
Arrange the items in a “spider key” before putting them
into the traditional dichotomous key format.
SPIDER KEY
DICHOTOMOUS KEY