Topic 4: Species And Taxonomy Flashcards
What is a species?
A group of organisms that can interbreed and produce fertile offspring
They have similar genes so are physically and biochemically similar but different from members of other species
What is classification?
The term to describe the grouping of organisms
3 features of a natural classification system
It is based on evolutionary relationships between organisms and their ancestors
Classifies features into groups using shared features derived from their ancestors
Arranges the groups into a hierarchy where groups are contained withing larger groups with no overlap between them
What are relationships between species in classification based on?
Homologous structures
They have similar evolutionary origins regardless of functions
E.g. wing of bird,human arm and horse front leg
They all have the same basic structure because they are all evolved from a common ancestor so are described as homologous
What is taxonomy?
It studies the classification groups and their positions in a hierarchical order where they are known as taxonomic ranks
6 key points about taxonomic hierarchy
1.organisms classified into groups called taxons, larger groups split into smaller
2. There is no overlap between taxonomic groups
3. Organisms are classified on the basis of similar or shared features
4. The more similar features individuals have, the more closely related they are
5. The fossil records can be used to determine similarities and differences in physical features
6. Hierarchy describes how different groups are arranged according to the size of the groups
What does it mean that there is no overlap between taxonomic groups?
An organisms must be a bird or a reptile it cant be halfway in between
Taxonomic groups in order
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Largest taxonomic rank
Domain
Smallest taxonomic group
Species
mnemonic to remember taxonomic groups
Do Keep Ponds Clean Or Frogs Get Sick
What are the 3 domains?
Bacteria
Eukarya
Archaea (group of prokaryotes)
How are species named? What is the name of this system?
Binomial system
The first name describes the genus an organism belongs to
The second name is to describe the species an organism belongs to
What is phylogeny
It describes the evolutionary relationships between different groups of organisms
It comes from the word ‘phylum’ which is a group of similar or related organisms
What are phylogenetic trees?
The phylogenetic relationships of different species represented by a tree like diagram
How are species represented in phylogenetic trees?
Oldest species at the base/start
Most recent ones are at the ends of branches
2 key points about phylogenetic trees
The more distantly related species has an earlier common ancestor
The more closely related species have a more recent common ancestor
Summarise the main features of natural classification
The evolutionary relationships between organisms and ancestors are studied
The phylogenetic groups are based on patterns of evolutionary history
Species are classified into groups based on shared characteristics
Groups are arranged in hierarchy, where large groups divide into smaller ones, there is no overlap between groups
What is the difference between a phylogenetic system and and a hierarchy?
Phylogenetic system is based on evolutionary history and shows the ancestry of groups, and points of divergence
Hierarchy is based on shared characteristics
Why is courtship behaviour needed?
1.to recognise members of their own species
2. To identify a mate capable of breeding
3. They form a pair bond
4. To synchronise mating
What difficulties might there be in identifying species?
Species aren’t fixed, they evolve over time
There can be significant variation among individuals in a species e,g, dogs
Many species are extinct and left no fossil records
Members of different groups of same species may be isolated so never meet or interbreed
Why are mules infertile?
When a horse and donkey gametes are fused they produce offspring with 63 chromosomes
A mule cannot produce gametes because of the odd number so is infertile
