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Cladistics - is a relatively new
system of phylogenetics
classification that uses shared
derived characters to establish
evolutionary relationships. A
derived character is a feature
that apparently evolved only
within the group under
consideration.
There are three basic assumptions
in cladistics:
1.Organisms within a group are
descended from a common
ancestor.
2.There is a bifurcating pattern of
cladogenesis.
3.Change in characteristics
occurs in lineages over time.
A phylogenetic tree based on a
cladistic analysis is called a
cladogram.
What derived character is shared by
all the animals on the cladogram on
the next slide?
The Dichotomous Key
• A key is a device for easily and quickly
identifying
an unknown organism.
• The dichotomous key is the most widely used
type in biological sciences.
• The user is presented with a sequence of
choices between two statements, couplets,
based on characteristics of the organism. By
always making the correct choice, the name of
the organism will be revealed.
A. one pair of wings
1.
B. Two pairs of wings
• Domain Archaea
– Includes newly discovered cell types
The Three
Domains
– Contains
1 kingdom – the Archaebacteria
•Domain Bacteria
– Includes other members of old kingdom Monera
– Has 1 kingdom – the Eubacteria
•Domain Eukarya
– Includes all kingdoms composed of organisms made
up of eukaryotic cells
– Protista
– Fungi
– Animalia
– Plantae
The major classification levels,
from most general to most specific
(several of these have subdivisions)
A group at any level is a taxon.
Categories within Kingdoms
Kingdoms are divided into groups called phyla
Phyla are subdivided into classes
Classes are subdivided into orders
Orders are subdivided into families
Families are divided into genera
Genera contain closely related species
Species is unique