Taxonomy involves both the classification and identification of living organisms. Classification involves grouping organisms in a hierarchical relationship based on their similarities, while identification separates one group from others based on unique characteristics. Together, classification and identification are the two main roles of taxonomists and systematicists in studying and classifying living things.

1. A. Taxonomy Defined
1. Grouping of organisms - the science of
classifying living organisms based on shared
features
2. Principles of classification – the practice
or principles of classification
3. Study of classification – the study of the
rules and practice of classifying living
organisms

2. QUESTION:
Would you also consider that
taxonomy deals with
IDENTIFICATION of living
organisms? Why or why not?

3. Taxonomy involves:
1. Classification – ranking of groups of
organisms in some hierarchical relationship
- based on their similarities in their
characteristics (genetic relationship, internal
and external anatomy, physiology or
evolutionary history)
2. Identification – separation of one group
from other groups according to their unique
characteristics

4.  Identifying organisms based on their
morphology, anatomy, physiology, cytology,
biochemistry and geographic distribution
WHAT ARE THE ROLES of TAXONOMISTS
and SYSTEMATICISTS?
To classify, identify and make a census
of the unique characteristics of each
species.

5.  To reconstruct the evolutionary history of the
present classified species based on
morphology, anatomy, chemical
composition, geographic
distribution, breeding behavior, and
chromosome number
 To determine which traits are advanced
(derived in time from primitive traits) or
primitive

6.  To discover all species of animals.
 To reconstruct their evolutionary
relationships.
 To classify animals according to their
evoutionary relationships.

7.  Unexplored areas, only an estimation could
be done
 Continuous evolution process (diversification)
 Continuous extinction
 How about in local settings?

8.  300 BC
Aristotle – used dichotomies or polar opposites
Ex. Animals with blood and without blood
(vertebrates and invertebrates)
- wrote extensively on both plants
and animals but his writings on plants were
lost
Theophrastus – Aristotle’s pupil and applied
his approach to the study of plants in his
work “Inquiry into Plants”

9. Theophrastus – subdivided plants based on
shape, and into broad categories as
trees, shrubs, and herbs
Dioscorides – developed a more practical
approach
- Ex. Medicinal herbs were separated
from those used in making perfumes

10. Polynomial System
-translation of the common names of
organisms into Latin
-each species was described in Latin by a
sentence limited to 12 words that begins with
the genus name
-Ex. Spiderwort -Tradescantia ephemerum
phalangoides tripetalum non repens
virginianum gramineum
Common name: Tradescantia virginiana

11. Translation: The annual, upright Tradescantia
from Virginia which has a grasslike habit, 3
petals, and stamens with hairs like spider
legs, common name Tradescantia of Virginia
But the polynomial system was simplified into a
two-word or BINOMIAL naming system in the
mid-16th century to mid-17th century by a
group of naturalists known as herbalists.

12. Andrea Cesalpino – first scientist to classify
plants primarily according to structural
characteristics, such as their fruits and seeds
Caspar Bauhin – adapted Cesalpino’s method;
catalogued an extensive list of plants

13. Animal Classification Advanced
Pierre Belon
– extensively studied and catalogued birds
-first to use adaptation to habitat to divide
birds as AQUATIC, WADING, PERCHING, and
LAND BIRDS and BIRDS of PREY

14. John Ray – used key characteristics such as the
shape and size of the birds’ beak to classify
birds
MID 1700s
Carolus Linnaeus
Binomial system of nomenclature – similar
organisms are grouped into a genus, and
each organism is given a two-word Latin
name

15. Carolus Linnaeus
Binomial nomenclature
first name – genus name
second name – adjective describing the
organism, its geographic location or the
person who discovered it
Ex. domestic dog
Canis familiaris

16. Canis – genus name for the group of animals
that includes dogs, wolves, coyotes, and
jackals
familiaris – acts as a descriptor to further
differentiate the domestic dog from its wild
cousins

17. Carolus Linnaeus – also designed the
HIERARCHICAL classification scheme
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species

18.  Development and use of microscopes
presented new classification problems which
still relied on a 2-kingdom classification
system (Plantae and Animalia

19.  Charles Darwin
-published “On the Origin of Species” in 1859
-argued that classification system should
reflect the history of life; species should be
related based on their shared ancestry
-emphasis on taxonomy shifted to:
a. A search for characters which reflected
genetic (evolutionary) relationships; and
b. The construction of a phylogenetic
classification scheme

20.  Phylogenetic – based on genetic, evolutionary
relationships
- which traits are primitive or
advanced

21. Ernst Haeckel
-proposed placing the unicellular forms in
kingdom Protista; placed bacteria within this
kingdom
1930s
Edouard Chatton – distinguished prokaryotes
and eukaryotes

22. Herbert Copeland
-prokaryotes in the 4th kingdom, Monera
1950s
Robert Whittaker
-proposed adding a 5th kingdom, Fungi
1970s
Advances in molecular systematics

23. Polymerase chain reaction – permits easy
analysis and comparison of DNA structures
Carl Woese – determined that archaebacteria
were found to have unique molecular
structures and physiological characteristics
from bacteria
-proposed a 6-kingdom
classification system

24. Other scientists propose an 8-kingdom system

25.  Modern animal taxonomy was established
using evolutionary systematics and recent
cladistic revisions.
 PhyloCode
-new taxonomic system
-being developed as an alternative to
Linnaean taxonomy
-replaces Linnaean ranks with codes that
denote nested hierarchy of monophyletic
groups converged by cladograms

26.  The terms
“primitive”, “advanced”, “specialized”, and
“generalized” are used for specific
characteristics and not for groups as a whole.