1. 5.3 Classification

2. Classification
For centuries, humans have been attempting to classify the various species on Earth in order to learn more about the species and their evolutionary history.
Classification attempts to group more related species together

3. Binomial System of Nomenclature
A “2 name” naming system that was designed by Carolus Linneaus in the 18th century.
Every species has a Latin name,
The first part of the name is the name of the genus, the second part is the species.
The name is printed in italics
If hand written, underline the name
The first letter of the genus is capitalized
The first letter of the species is not

4. Examples: Humans: Homo sapiens GENUS SPECIES
Dogs: Canis lupus familiaries
SUBSPECIES

5. Linnaeus’ system was largely based on morphology and is not the best way to classify organisms
(Modern methods use evolutionary relationships to classify organisms)
However, Linnaeus’ system is still the basis of how we name organisms today.

6. International Cooperation & Classification
Scientists all around the world use the binomial system as a universal naming system to identify a species rather than the many local names

7. Hierarchy of Taxa
Taxonomists classify species using a hierarchy of taxa
TAXON = group of something
Taxon (singular), taxa (plural)
The taxa form a hierarchy, as each taxon includes taxa from the level bellow

8. Three Domains
Traditional classification systems have recognized 2 major categories of organisms based on cell types: eukaryotes and prokaryotes
Think back to Topic 1 in grade 11. Do you remember the difference?

9. Three Domains
Because prokaryotes are so diverse, most classifications systems recognize 3 major categories or domains
Eubacteria (bacteria) Types of
Archaea (archaeans) prokaryotes
Eukaryota (eukaryotes)

10. Histones Associated with DNA
BACTERIA
ARCHAEA
EUKARYOTA
absent
Proteins similar to histones bound to DNA
Present

11. Presence of Introns BACTERIA ARCHAEA EUKARYOTA Rare or absent
Present in some genes
Frequent

12. Structure of Cell Walls
BACTERIA
ARCHAEA
EUKARYOTA
Made of chemical peptidoglycan
Not made of peptidoglycan
Not made of peptidoglycan, not always present

13. Cell Membrane Difference
BACTERIA
ARCHAEA
EUKARYOTA
Glycerol-ester lipids;
Unbranched side chains;
D-form of glycerol
Glycerol-ether lipids;
L-form of glycerol

14. Archaeans Found in a broad range of habitats:
Ocean surface
deep ocean sediments
oil deposits below the Earth’s surface
High salt concentrations
High temperatures
Ex: methanogens which live in the intestines of cattle and produce methane as a waste product.

15. Hierarchy of Classification for Eukaryotes
Seven level hierarchy of taxa to classify organisms
Kingdom
Phylum
Class
Order
Family
Genus
Species

16. Kingdoms Kingdoms are the broadest category
Originally there were only 2 Kingdoms: Plants and Animals
Today, we have identified 5

17. Modern Kingdoms Kingdom Plantae (plants) Kingdom Animalia (animals)
Kingdom Fungi (fungi and moulds)
Kingdom Protoctista (protozoa and algae – includes paramicium and amoebas)
Kingdom Prokaryotae (bacteria)

18. Examples of Classification
You need to know an example of 1 plant and 1 animals species from domain to species level
See page 262 for an example of the grey wolf and the date palm

19. Ex: Humans KINGDOM Anamalia PHYLUM Chordata CLASS Mammalia ORDER Prima
FAMILY
Hominidae
GENUS
Homo
SPECIES
sapiens

20. Ex: Garden Pea KINGDOM Plantae PHYLUM Angiospermae CLASS
Dicotyledoneae
ORDER
Rosales
FAMILY
Papilionaceae
GENUS
Pisum
SPECIES
sativum

21. Natural Classification
The genus and accompanying higher taxa consist of all the species that have evolved from one common ancestor
Because of the common ancestor we can expect the members of a natural group to share many characteristics

23. Natural vs Artificial Characteristics
Plants and fungi were one time classified together because they both have cell walls, but this is an artificial classification as their cell walls evolved separately and molecular research shows they are no more similar to each other than to animals.

25. Natural vs Artificial Characteristics
Ex: wings of insects, birds, and bats
We will come back to this when we talk about convergent evolution and analogous traits.

26. Reviewing Classification
Sometimes taxonomists reclassify species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species
The new evidence is usually DNA sequencing

27. Advantages of Natural Classification
Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group

28. Plants All plants are found in a single kingdom
During the life cycle of a plant, male and female gametes develop and fuse to form a zygote, which will develop into an embryo and then the particular plant

29. Expectation, page 266
Distinguish between the following phyla of plants using simple external recognition features
Phyla: bryophyte ,filicinophyta, coniferophyta, angiospermophyta

30. Bryophyta Mosses and liverworts
Small terrestrial plants that do not have true roots, stems or leaves (but may have similar structures)
Leaf-like structures arranged in a spiral
Usually live in clusters

31. Filicinophyta Ferns Have true leaves New leaves unroll
Have an underground creeping stem (called a rhizome)

32. Coniferophyta Conifers
Woody plants, with a single wooden trunk and side branches
Leaves are long thin needles and dark green
Produce seeds in cones

33. Angiospermophyta Angiosperms/ Flowering Plants Have flowers
Seeds are in ovaries with become the fruit
Leaves usually as a leaf blade and a leaf stalk, with veins visible on the lower surface

34. Animal Phyla Animals are divided into over 30 phyla
Distinguish between the following phyla of animals, using simple external recognition features. (see page 267)

35. Porifera Sponges Most primitive animals with a simple body
Live in water
Do not move around
No mouth, but have small holes through which water is pumped into body and have be filtered for food before pumping out

36. Cnidaria Jellyfish and sea anemones Have stinging cells
Radially symmetrical
Have a gastro-vascular cavity (a hollow space in the centre of the body) with only one opening to the cavity
Often have tentacles around the opening

37. Plathyelminthes Flatworms
Soft flattened body with a definite head region
Bilateral symmetry
Gastro-vascular cavity
Usually one opening to cavity
Live in water or damp environments
Can be free-living or parasitic

38. Arthropoda Animals with jointed legs
Ex: insects, arachnids, crustaceans
Exoskeleton made of chitin (a polysaccharide)
Segmented body
Appendages to each segment
At least 3 pairs of legs
May be free living or parasitic

39. Annelida Worms and leeches Bodies of ring-like segments
Have a mouth and an anus
Live in water or moist soil
May be free living or parasitic
No legs
Bristles from body which help them move

40. Mollusca Snails, squids, clams, slugs Soft unsegmented bodies
May have a shell

41. Chordates - Vertebrates
All are vertebrates because they have a backbone composed of vertebrae
There are 5 major classes of chordates
You need to recognise the features of birds, mammals, amphibians, reptiles, and fish (page 268)

42. Birds Skin with feathers made of keratin 2 legs, 2 wings
Females lays eggs with shells
Maintain constant body temp

43. Mammals Skin with follicles with hair made of keratin
Lungs with alveoli, ventilated used ribs and diaphragm
Give birth to live young and all feed young with milk from mammary glands
Maintain constant body temperature

44. Amphibians Soft moist skins permeable to water and gases
Simple lungs with small folds and moist skin for gas exchange
4 legs as an adult
Larval stages lives in water and as an adult usually lives on land
Do not maintain constant body temp

45. Reptiles Impermeable skin covered in scales of keratin
Lungs with extensive folding to increase the surface area
Female lays eggs with soft shells
Do not maintain constant body temp

46. Fish Scales with are bony plates in the skin Gills No limbs
Remain in water throughout their life cycle
Do not maintain constant body temp

47. Dichotomous Keys
Apply and design a key for a group of up to eight organisms.
Keys are most commonly used to identify plants, insects, and birds.
You need to be able to construct a dichotomous key page 265