Linneaus
Taxonomy
common names Fig 18.2
polynomial nomenclature
binomial nomenclature Genus (genera) and species = scientific name Fig 18.1
hierarchical classification (Fig 18.3)
taxon (taxa)
only species exist in nature as biologically cohesive
units
John Ray defined biological species concept Fig. 18.4
Phylogeny leads to
classification (Image)
Systematics - The
goal of systematics is
to have classification reflect the evolutionary relationships of species.
Phylogenetic
systematics (Cladistics)
Cladistics classifies
organisms according to the order in time that branches arise along a
phylogenetic tree, without considering the degree of divergence (how much
difference).
- cladogram (Fig 18.5)
- ancestral characters
- derived characters
A phylogenetic tree
must be
- A monophyletic taxon = a clade (Image)
- NOT a polyphyletic
taxon
Morphological
characters used
in determining the phylogeny of a group:
- Analogous
structures result
from convergent
evolution (Image)
-
Analogy vs. homology (Image)
- Homologous
structures evolve
from the same ancestral structure though the function may differ.
Other characters can be used: ecology,
physiology, molecular.
Fig 18.7.
Traditional taxonomy
weights some characters more than others. Fig 18.6
CONSTRUCTING
PHYLOGENIES (Image)
A phylogenetic tree should have an outgroup that is a closely related taxon recently ancestral to the
organisms for which the phylogeny is being constructed. Ingroups share derived characteristics that the
outgroup does not have. To determine characters to use, must determine if it is
analogous or homologous. If homologous, must then decide if character is
ancestral or derived. Movie
Fig 18.8 - several systems of classification
Classification
schemes - the Movie!
Domain Archaea
contains Kingdom Archaea
Methanogens
Extremophiles
Non-extreme
Archaea
Domain Bacteria
contains Kingdom Bacteria
Domain Eukarya contains
3 valid kingdoms plus one kingdom of convenience
A tree of life. Fig. 18.9.
Relationships between
the kingdoms. Fig 18.10
Relationships between
the domains. Image
Characteristics of the
kingdoms. Table
18.1
Visit the Tree of Life to view the systematics of
all living organisms.
Berkeley's Introduction to
Systematics.
Berkeley's Introduction to Cladistics.