Classification
(Taxonomy)
-naming and classification of
species
Topics:
• History of
classification
• Current Scheme
• Five/six kingdom
system
• Kingdoms
overview
Introduction
• To trace phylogeny (the evolutionary history of life) biologists use
evidence from paleontology, molecular data, comparative
anatomy, etc.
• Tracing phylogeny is one of the main goals of systematics, (the study of
biological diversity in an evolutionary context.)
• Systematics includes taxonomy, which is the naming and
classsification of species and groups of species.
As Darwin correctly predicted, “our classifications
will come to be, as far as they can be so made,
genealogies.”
Aristotle
(384 BC to 322 BC)
His classification system was
based on structural
differences that were seen.
Carolus Linnaeus (1707-1778)
Swedish Botantist
based his
classification on characteristics of
organisms that were similar.
Developed the two word system used to identify species: binomial nomenclature.
Taxonomy employs a hierarchical
system of classification
• First formally proposed
system.
• Systema naturae in the 18th
century, has two main
characteristics.
• Each species has a two-part
name.
• Species are organized
hierarchically into broader and
Carolus Linnaeus
(1707-1778)
Binomial Nomenclature.
• Each species is assigned a two-part latinized
name, a binomial.
• The first part, the genus, is the
closest group to which a species
belongs.
• The second part, the specific epithet,
refers to one species within each
genus.
• The first letter of the genus is
capitalized and both names are
Hierarchical Classification
Taxons
• Groups species into broader
taxonomic categories.
• Species that appear to be
closely related are grouped
into the same genus.
• For example, the leopard,
Panthera pardus, belongs to a
genus that includes the African
lion (Panthera leo) and the tiger
(Panthera tigris).
• Biology’s taxonomic scheme
formalizes our tendency to group
related objects.
From Kingdom to Species
Timeline of Classification
1. 384 – 322 B.C. Aristotle
 2 Kingdom Broad Classification
2. 1735 - Carl Linnaeus
 2 Kingdom Multi-divisional Classification
 Kingdom, Phylum, Class, Order, Family Genus,
Species
3. Evolutionary Classification – (After Darwin)
 Group By lines of Evolutionary Descent
4. 5 Kingdom System – 1950s
5. 6 Kingdom System – 1990s
6. 3 Domain System – 1990s
Phylogenetic Trees reflect the hierarchical classification of
many taxonomic groups.
Phylogeny
is
determined
by a
variety of
evidence
including
fossils,
molecular
data,
anatomy,
and other
features.
Modern phylogenetic systematics is based on
cladistic analysis
• Most systematists use cladistic analysis,
developed by a German
entomologist Willi Hennig
to analyze the data
• A phylogenetic diagram or
cladogram is constructed
from a series of
dichotomies.
Systematics-the study of biological diversity in an evolutionary context.
• These dichotomous branching diagrams can
include more taxa.
• The sequence of branching symbolizes
historical chronology.
• The last ancestor
common to both the
cat and dog families
lived longer ago
than the last common
ancestor shared
by leopards and
domestic cats.
branch or clade
Can not always base clade on appearance.
• It is especially important to distinguish similarities that are based
on shared ancestry or homology from those that are based on
convergent evolution or analogy.
• These two desert plants are not closely related but owe their resemblance
to analogous adaptations (convergent evolution).
• The presence
good
distinguish the
mammals
tetrapods.
of hair is a
character to
clade of
from other
Analyzing the taxonomic distribution of
homologies enables us to identify the
sequence in which derived characters evolved
during vertebrate phylogeny.
A cladogram presents the chronological
sequence of branching during the evolutionary
history of a set of organisms.
Systematics is the study of the diversity of organisms using
information from cellular to population levels.
1. Classification reflects phylogeny; one goal of systematics is to
create phylogenetic trees.
2. Phylogeny is the evolutionary history of a group of organisms.
3. A phylogenetic tree indicates common ancestors and lines of
descent.
4. A primitive character is a trait that is present in a common
ancestor and all members of a group.
5. A derived character is present only in a specific line of
descent.
6. Different lineages diverging from a common ancestor may have
different derived characters.
Molecular clocks may keep track of
evolutionary time
• The timing of evolutionary events has rested primarily
on the fossil record.
• Recently, molecular clocks have been applied to place
the origin of taxonomic groups in time.
• Molecular clocks are based on the observation that some
regions of genomes evolve at constant rates.
• For these regions, the number of nucleotide and
amino acid substitutions between two lineages is
proportional to the time that has elapsed since
they branched.
• For example, the homologous proteins of bats
and dolphins are much more alike than are those
of sharks and tuna.
• This is consistent with the fossil evidence that sharks
and tuna have been on separate evolutionary paths
much longer than bats and dolphins.
• In this case, molecular divergence has kept better
track of time than have changes in morphology.
Six Kingdoms of Life
Eukarya
Archaea
Archaebacteria
Bacteria
EuBacteria
Plantae
Protista
Fungi
Animalia
Six Kingdoms of Life
•Archaebacteria
•Eubacteria
•All Single celled prokaryotes
•Anaerobes and aerobes
•One circular chromosome
•Heterotrophic and
autotrophic
Six Kingdoms of Life
Protista
•Widest variety of organisms
•All eukaryotes
•Single and multicellular
•Heterotrophic and
autotrophic
Six Kingdoms of Life
Fungi
•All Heterotrophic
•Eukaryotic
•Single and multicellular
•Important as decomposers
•Cell walls made of chitin
•4 divisions
Six Kingdoms of Life
Plantae
•All Autotrophic
•Eukaryotic
•All multicellular
•Cell walls made of cellulose
•10 divisions
Six Kingdoms of Life
Animalia
•All heterotrophic
•All Eukaryotic
•All multicellular
•35 phyla
Mrs. Payne