Classification
The nature of species
Tom Hartman
www.tuatara9.co.uk
Animal form and function 1
Module 11112
What is taxonomy?
• Naming the animals (Creation story)
• Grouping similar kinds together.
– Morphological data
– Molecular data (some surprises)
• Working with convergence.
Some genus and species
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Aa (1940) a mollusc
Choas (1767) a protistan
Batman (1956) a fish
Zyzzyx (1937) a wasp
Aha ha (1977) a wasp
Montypythonoides riversleighensis (1985) a snake
Polemistus chewbacca (1983) a wasp
Polemistus vaderi (1983) a wasp
Upopa epops (1758) a bird
What is classification?
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A rigid system!
DO NOT buck the nomenclature!
Binomial system Genus species!!!
Homo sapiens not Homo Sapiens or Homo
sapiens, etc.
• In scientific literature you read about
Tyrannosaurus rex
• It is, however, a type of tyrannosaur.
Categories
Classification acts as a retrieval system to collect and
order data on relationships between different
organisms.
Domain
Phylum
Class
Order
Family
Genus
Species
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Ranking
Species
Ranking
Suborder
Carnivora
Order
Class
Subphylum
Chordata
Phylum
Phylum
Animalia
Kingdom
Tyrannosauridae
Family
Theropoda
Saurischia
Order
Mammalia
Kingdom
Eukarya
Domain
Tyrannosaurus rex
Tyrannosaurus
Genus
Felidae
Family
Class
Species
Panthera
Genus
Domain
Panthera
pardus
Reptilia
vertebrata
Chordata
Animalia
Eukarya
Homologous structures
Relationships
• Tyrannosaurus rex and Panthera pardus
have many things in common.
– Animals, chordates, vertebrates
– Tetrapods, amniotes
• But many things separate them too e.g.
– Skull architecture
– Tooth differentiation
Human
Homology
Cat
Whale
Bat
Analogous structures
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Analogy
Convergence
Convergence
(a) Tuna
(b) Shark
(f) Ichthyosaur
(c) Penguin
(d) Dolphin
(g) Plesiosaur
(e) Seal
• The detectable species: "a species is
composed of those specimens that the
taxonomist believes to be conspecific.“
• Huge changes since molecular techniques
have been introduced.
• Vast detection of new orders in sea water
samples BUT no one knows what they are
from.
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• The morphological species: "Species are
the smallest groups that are consistently and
persistently distinct and distinguishable by
ordinary means." This is the most useful
definition for practical purposes.
• The biological species: A species is "a group of
interbreeding
populations
which
are
reproductively isolated from other such groups".
• A refinement of this definition is the Genetic
species where a more quantifiable standard is used
to measure genetic distance; either by comparing
protein or DNA sequences.
• The evolutionary species. "An evolutionary
species is a lineage evolving separately from
others and with its own evolutionary role and
tendencies".
• The cladistic species is further defined as being a
single lineage of ancestral-descendant populations
of organisms which maintains its identity from
others and is thus also subject to the same
problems.
• The biosystematic species concept is one
defined by the diversity of reproductive
relationships.
Modern taxonomy
Classification has moved away from the simple
grouping of organisms according to their similarities
(phenetics) and has become the study of patterns of
diversity within an evolutionary context (systematics).
Knowing lots about lots of creatures.
Systematics includes:
1.
taxonomy
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Systematics includes:
1.
2.
taxonomy
phylogenetic reconstruction which attempts to
identify shared, derived characters
(synapomorphies).
Tuna
Salamander
Turtle
Leopard
Hair
0
0
0
0
0
1
Amniotic (shelled) egg
0
0
0
0
1
1
Four walking legs
0
0
0
1
1
1
Hinged jaws
0
0
1
1
1
1
Vertebral column (backbone)
0
1
1
1
1
1
CHAR ACTERS
Lancelet
(outgroup)
Lamprey
TAXA
Turtle
Systematics includes:
(a) Character table. A 0 indicates that a character is absent; a 1
indicates that a character is present.
1.
2.
taxonomy
phylogenetic reconstruction which attempts to
identify shared, derived characters
(synapomorphies).
Leopard
Hair
Salamander
Amniotic egg
Tuna
Four walking legs
Lamprey
Hinged jaws
Lancelet (outgroup)
Vertebral column
(b) Cladogram. Anal yzing the distribution of these
derived characters can provide insight into vertebrate
phylogeny.
Shared characters
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Four egg laying vertebrates
Four tetrapods
One scaly
Two feathery (and scaly)
One hairy
Shared characters
• Three have complex skull architecture
• One has a simple skull architecture
• Three have no teeth
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Shared characters
Some characters are widely distributed
• Live bearing
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Three have four chambered hearts
Three have a high metabolism
Three show parental care
One produces milk from mammary glands
Systematics includes:
1.
2.
3.
taxonomy
phylogenetic reconstruction which attempts to
identify shared, derived characters
(synapomorphies).
A classification that organises the data into a series of
interconnected ranks. In the past groups were defined
by shared characters such as scales, fur or feathers;
now they are defined by common ancestry.
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