Topic 5.5
Classification
Why Classify?
1. How many ‘different
sorts’ of living things are
there on the planet?
How many species are there in
the world?
Let’s start with some
classification!
Take 5 minutes to write down ways in which we can
classify the students in class today
Key features of a classification key are that it must be
clear, consistent, and easily implemented
Why Classify?
In order to sort out and compare living things, we need
to organise them into ‘manageable’ categories
A good classification system allows us to make
generalisations AND organise our ideas about
organisms
Classification involves giving every organism an
AGREED NAME
Classification involves arranging organisms into
apparently related organisms
The American
Robin
(Turdus
Migratorius)
The European
Robin
(Erithracus
Rubecula)
What is taxonomy?
Taxonomy is the
process of
(scientific)
classification
Taxis: Greek for ‘Arrangement or
Division’
‘Nomos’: Greek for ‘Method or
Law
http://www.youtube.com/watch?
v=F38BmgPcZ_I
Systems used to classify living
organisms
Linnaean Binomial Nomenclature system
Cladistics (Ancient Greek –Branch)
Phylogenetics
The evolution of taxonomy…
The Linnaean classification system was created long before scientists
understood that organisms evolved. Because the Linnaean system is
based on morphology (form and structure) rather than on
evolutionary theory
Most biologists are switching to a classification system that reflects
the organisms' evolutionary history
•
Phylogenetic tree
•
Cladogram
Cladistics
A taxonomic system based on
common evolutionary ancestry
The Method of choice for
classifying organisms, since it
recognises and involves
evolutionary theory
Developed since 1958
Any group of organisms are related
by descent from a common ancestor.
There is a bifurcating pattern of
cladogenesis.
Change in characteristics occurs in
lineages over time.
Cladistics introduction
Phylogenetic tree
An ‘Evolutionary Tree’
Shows inferred
evolutionary relationship
among species based on
similarities/differences in
their genetic material or
physical appearance
Linnaean Classification
Developed by Carl Linneaus
Swedish botanist & taxonomist
Is still used today, basis for
classification and naming of all
new species.
Based on physical traits, most
of his classifications are still
accurate.
http://www.youtube.com/watc
h?v=F38BmgPcZ_I
Binomial Nomenclature
Each species is assigned a two part scientific name.
Written in italics
If handwritten, underline the name
First word is capitalized (Genus): NOUN
Second word is lowercase (Species): ADJECTIVE
Binomial Nomenclature
Homo sapiens
Modern human
Genus
species
Eretmochelys imbricata
Hawksbill Turtle
(imbricate: arrange so that they overlap like tiles)
The genus name can be abbreviated if you have already used the full name in your text
Linnaeus also defined four groups of humans, and the
divisions were based on both physical and social traits.
By 21st-century standards, his descriptions can be
regarded as racist.
How does the social context of scientific work affect
the methods and findings of research?
Is it necessary to consider the social context when
evaluating ethical aspects of knowledge claims?
There are seven (err, actually 8) levels
of classification
Biological taxonomy is
hierarchical
As we move from kingdom
(domain) to phylum, all the way
to species, organisms share
more and more characteristics.
This system allows us to group
organisms while also assigning
unique species names.
(Domain)
King
Philip
Came
Over
For
Good
Spaghetti
How is Life Classified?
Pre-1969: Life is classified into 2 Kingdoms: Plantae and
Animals
1969 – 1999: Life is classified into 5 Kingdoms: Monera,
Protista, Plantae, Fungi, Animalia: using Linnaean
Classification System – based on anatomy,
morphology, embryology and cell structure
BUT: The Traditional 5 kingdom System does not explain
how kingdoms may be related through evolutionary
relationships among the kingdoms
The Three Domains
Karl Woese discovery of
Archae
The 3 domains were proposed
by Dr Karl Woese
Dogma
The eukaryote-prokaryote dichotomy was the central
dogma of biology. Woese was making a claim of
extraordinary scope. He was saying that we had missed
one-third of all living things. People did not like that
(5). "I hadn't been trained as a microbiologist, so I
didn't have this bias" [about impossibility of bacterial
classification]. (Woese)
Classification is a ‘messy’
branch of science…
Just compare the University of Oxford and the University
of Berkeley…
Oxford University Museum of
Natural History
5 Kingdoms:
one
prokaryotic,
four eukaryotic
University of California Berkeley
Classification in the Animal
Kingdom
Kingdom
Animalia
Contains organisms as diverse as
coral and mice….
Classification in the Plant
Kingdom
Plant Classification (UMCB)
From Kingdom…
Linnaeus originally divided
living things into 2
(then 3) kingdoms…
Animalia
Vegetalia (Plants)
Mineralia (Minerals,
since abandoned)
We now widely recognise FIVE
kingdoms:
1.
Kingdom Plantae (the plants)
2.
Kingdom Animalia (the animals)
3.
Kingdom Fungi (the fungi and
moulds)
4.
Kingdom Protocista (protozoa and
alga)
5.
Kingdom Prokaryote [Monera]
(the euBacteria and archebacteria)
Kingdom Animalia
Eukaryotic
Multicelluar
Heterotrophic
Terrestrial and aquatic
Sexual (a few are asexual)
Motile (a few are nonmotile)
Kingdom Plantae
1.
Eukaryote
2.
Multicellular
3.
Autotrophic
4.
Mostly terrestrial
5.
Sexual and asexual
6.
Nonmotile
Mosses, Ferns, flowering
plants, conifers
Kingdom Fungi
Eukaryotic
Heterotrophic
Unicellular and multicellular
Mainly terrestrial
Asexual and sexual
Non-motile
Mushrooms, puffballs, yeasts,
rusts, water moulds
Kingdom prokaryotae
(Monera)
Prokaryotes
Heterotrophic and
autotrophic
Anaesrobic and aerobic
Aquatic, terrestrial and
aerosol
Mostly asexual
Mostly non-motile (one kind
are motile)
Kingdom Protoctistae (Protists)
Eukaryotes
Heterotrophic and
autotrophic
Unicellular
Brown Algae
Mostly aquatic
Mostly asexual
Motile and non-motile
Protozoa, slime moulds, algae
…To Species
A group of organisms which can interbreed and produce
fertile offspring.
Species are named: Genus species
Heliconius charithonius
The smallest taxonomic group, though many subspecies are
recognized.
Might potentially interbreed
if a barrier or other challenge
was removed (ie: distance)
Test yourself
Classification of the malaria
parasite, Plasmodium falciparum
Kingdom Protista
(Subkingdom) Protozoa
Phylum: Apicomplexa
Class: Sporozoasida
Order: Eucoccidiorida
Family: Plasmodiidae
Genus: Plasmodium
Species: falciparum,
malariae, ovale, vivax
Classification of the malaria vector:
Aedes Aegyptae
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Culicidae
Subfamily: Culicinae
Genus: Aedes
Species: Aegyptae
Now your turn: IB
Classification Requirements
5.5.2: List seven different levels in the hierarchy
of taxa: kingdom, phylum, class, order, family,
genus and species, using an example from two
different kingdoms for each level
Scenic Oregon Hierarchical Classification
Use the Scenic Oregon I-animal website to write
information about an animal of your choice
Use the University of Berkeley Website to write
information about a plant species of your choice
5.5.3 Distinguish between the following
phyla of plants, using simple external
recognition features
Resources:
Clegg, P. 165 – 168
Evolution Drop-down
menu in the Blog has
resources on all major
plant phyla
5.5.4 Distinguish between the
following phyla of animals, using
simple external recognition features:
porifera, cnidaria, platyhelminths,
annelida, mollusca and arthropoda
Resources:
Clegg, P. 165 – 168
Evolution Drop-down menu in the Blog
has resources on all major invertebrate
phyla
Classification of the
Kingdoms: Synonyms
One prokaryote
kingdom
Four eukaryote
Kingdoms
Bacteria
Protoctista
Monera
Fungi
•
No nucleus
Plantae
•
Divide by binary fission
(asexual)
Animalia
Dichotomous Keys
From classification to
dichotomous keys…
Classification and identification go hand in hand. Once
identified, organisms can be classified by placing them in groups
that have similar characteristics. To determine the scientific name
of an organism, taxonomists use a process of elimination, called
keying, to assist them.
A dichotomous key is constructed so that pairs of contrasting
characteristics are set up in a precise sequence. Each step in the
identification process involves the selection of a characteristic from
each pair.
Now try some yourselves…
Dichotomous keys trees of oregon
Florida Keys Flowers
http://www.pbs.org/wgbh/nova/nature/classifyinglife.html
Simple Tree dichotomous key
Wednesday/ Thursday
Starting on Topic G3: Impacts of Communities on
Ecosystems