“Grouping together items into categories based on a set criteria”
Group Activity
-get yourselves into groups of 4
-Brainstorm and list 20 domesticated
animals
-your job is to group your list of animals into
different categories
-you MUST:
-use more than three categories
-be prepared to describe the criteria you
used for your groupings
“Systematic grouping of organisms into categories on the basis of defined criteria”
Taxonomy
“the science of classifying ALL organisms”
-Very general
- millions of species?
- how to start classifying?
• behaviour
• where they live/habitat
• appearance and characteristics
(MORPHOLOGY)
Mosquitoes –50 species
Seed plants – 260 000 species
Challenges to Classification?
- Yesterday?
• Variation:
o over space and time
o among individuals
DNA
Evolution
The biggest classification problem has always been consistency
(Coles notes)
• Ancient Greece
-First to introduce classification and binomial definition
- classify ALL LIVING things (Historia Animalium)
- blood/no blood, water/land
-Hierarchical; each organism fixed position
Great
Chain of
Being
Aristotle
(384 – 322 BC)
• Humans
• Animals
• Plants
Issues?
-complex plants below
simple animals
-little genetic
relationship
-Evolution?
-Virtually no innovation to Aristotle’s work till the 16th century
-virtually 2000 years!!!
-shamans/Aboriginal healers/Andrea Cesalpino
• Irregularity amongst names
-needed agreed upon set of naming guidelines
-Scientific naming
- the father of taxonomy
- 2 key contributions to classification:
1.
Consistent way of grouping species according
to morphological similarities
2.
Naming system
- 2 parts
1. Genus  species; capitalized, italicized
2. species  specific species; italicized
Gerbera hybrida
-standard naming system for all organisms
Systema Nature (1735)
-simple
-convenient
-flawed
Ursus americanus
Share many
characteristics
Ursus maritimus
Share few
characteristics
Phascolarctus cinereus
General/fewer similarities
kingdom
Animalia
phylum
Chordata
class
Mammalia
order
Primates
family
Hominidae
genus
Homo
species
sapiens
Ranks based on
shared
characteristics
-each level = taxon
Specific/more
- refined into subcategories
“structure in which a large set of items is broken down into smaller subset,
ultimately leading to the smallest available classification unit.”
- series of branching two-part statements used to identify organisms
- large set broken down to smallest classification unit
- larger number of species, the more specific questions become
Difficulties?
• number of species
• distinguishing
characteristics are internal
• agreeing on criteria
Dichotomous Key practice
Page 18
Textbook
Activity
Get into groups of 4-6
Within your group you will be creating your own dichotomous key
The subject of your key will be classifying each member
of your group
Remember dichotomous keys “are a series of
branching two-part statements used to identify
organisms.”
Therefore your keys need to
contain multiple steps and be specific
When, finished, you must demonstrate the viability of your key to Mr.
Faulhafer for assessment
Complete questions 5 and 8 on page 20 of textbook