1. Classification
Noadswood Science, 2016

2. Classification To describe classification methods
Sunday, April 15, 2018
To describe classification methods

3. Precise Learning
Traditionally living things have been classified into groups depending on their structure and characteristics in a system developed by Carl Linnaeus.
Linnaeus classified living things into kingdom, phylum, class, order, family, genus and species. Organisms are named by the binomial system of genus and species
Students should be able to use information given to show understanding of the Linnaean system (understand how scientific methods and theories develop over time)
Students should be able to describe the impact of developments in biology on classification systems
As evidence of internal structures became more developed due to improvements in microscopes, and the understanding of biochemical processes progressed, new models of classification were proposed.
Due to evidence available from chemical analysis there is now a ‘three-domain system’ developed by Carl Woese. In this system organisms are divided into:
Archaea (primitive bacteria usually living in extreme environments)
Bacteria (true bacteria)
Eukaryota (which includes protists, fungi, plants and animals)
Evolutionary trees are a method used by scientists to show how they believe organisms are related. They use current classification data for living organisms and fossil data for extinct organisms (interpret evolutionary trees)

4. Classification
There are millions (maybe tens of millions) of different species on Earth – some organisms are clearly different, whilst others share many similar features
Compare a cow and dolphin – they appear very different, but what features do cows and dolphins have in common?

5. Common Features

6. Common Features
Many organisms share common features, which allow them to be grouped based on these features – this is classification
The classification system begins with very big groups (lots of organisms) and moves down into smaller groups (fewer organisms)
The biggest groups are called the kingdoms, of which there are 5

7. Linnaean
Traditionally organisms have been classified according to a system first proposed in the 1700s by Carl Linnaeus
Living things are grouped according to their characteristics and the structures that make them up

8. Linnaean System
In the Linnaean system living things are first divided into kingdoms which are then subdivided into smaller groups (phylum, class, order, family, genus, species)
In this system a human is classified as Animalia > Chordata > Mammalia > Primates > Hominidae > Homo > sapiens

9. Three Domain
The three-domain system proposed by Carl Woese based in biochemical processes allowed new classification models to be proposed
Archaea > primitive bacteria
Bacteria > true bacteria
Eukaryota > fungi, plants, animals and protists (then subdivided into kingdom, phylum, class, order, family, genus and species)

10. Binomial System
In the binominal system each organism is given its own two- part Latin name
The first part refers to the genus that the organism belongs to and the second part refers to the species

11. Evolutionary Trees
Evolutionary trees show how scientists think different species are related to each other
They show common ancestors and relationships between species – the more recent the common ancestor the more closely related the two species (and the more characteristics they are likely to share)
For current species DNA is used for working out evolutionary relationships whilst fossils are used for extinct species

12. Evolutionary Trees
In an example of an evolutionary tree whales and dolphins have a recent common ancestor so are closely related (and both are more distantly related to sharks)

13. Evolutionary Tree
In the evolutionary tree below the relationships are shown between humans and some of the great apes along with their common ancestors…

14. Practice Questions – Application
The tree below shows the evolutionary relationships between some of the big cats
Which animal is most closely related to the leopard
Which animals is most closely related to the tiger?
Which animal evolved first – the jaguar or lion?
Do the lion and snow leopard share a common ancestor?

15. Answers Which animal is most closely related to the leopard – lion
Which animals is most closely related to the tiger – snow leopard
Which animal evolved first – the jaguar or lion – jaguar
Do the lion and snow leopard share a common ancestor – yes (but it is the most distantly related)