Topic 4B (Part 2) - Diversity Classification and Variation Flashcards
What is phylogeny?
The study of the evolutionary history of groups of organisms, to tell us who’s related to whom and how closely related they are
What does the 1st branch of a phylogenetic trees represent?
It represents a common ancestor of all the family members in a phylogenetic tree
- This ancestor is now extinct
How do we know if species are closely related on a phylogenetic tree?
They would diverge away from each other more recently
What is taxonomy?
Naming and organising organisms into groups, so that they could be classified, identified and studied
How has the study of classification changed over the years?
Scientists now take into account phylogeny and group organisms according to their evolutionary relationships
What is a taxon? (PLURAL: taxon)
One of the 8 levels of groups used to classify organisms
How are taxons arranged?|
They are arranged in a hierarchy, with the largest groups at the top and smallest at bottom
- Organisms can only belong to one group at each level in the hierarchy - there’s no overlap
Name the 3 domains
- Eukarya
- Bacteria
- Archaea
Name the 8 taxons
Daddy Kylie Puts Carrots on Fish Goat Soup
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What happens as you move down the hierarchy?
- There are more groups at each level but fewer organisms in each group
- The organisms in each group also become more closely related
Define a species
It is a group that:
- contains only 1 type of organism and
- is made up of similar organisms that are able to reproduce to give fertile offspring
Why are classification systems always updated?
Because of discoveries about new species and new evidence about known organisms
What nomenclature (naming system) is used in classification?
The binomial system
How does the binomial system work?
All organisms are given 1 internationally accepted scientific name in Latin that has 2 parts
- 1st part is genus name and has capital letter (italic)
- 2nd part is species name and start with lower case (italic)
Why is the binomial system used?
To avoid confusion of using common names
What type of behaviour can be used to classify organisms?
Courtship behaviour
Why is courtship behaviour used to classify organism?
Its species specific: only members of same species will respond to it
How does the specificity of courtship behaviour benefit organisms?
It allow members of same species to recognise each other, preventing interbreeding and making reproduction more successful
Give examples of techniques/technologies that have helped clarify evolutionary relationships.
- Genome sequencing
- Comparing amino sequence
- Immunological comparisons
How has genome sequencing helped clarify evolutionary relationships?
Advances in genome sequencing have meant that entire base sequence of organisms DNA can be determined and then compared to DNA base sequence of another organism, to see how closely related they are (Closely related species will have a higher % of similarity in DNA base order)
How have immunological comparison helped clarify evolutionary relationships?
Similar proteins will also bind to same antibodies
- If antibodies to human version of a protein are added to isolated samples from other species, a protein that’s like human version will also be recognised by antibody
Look at questions on interpreting data on DNA and protein similarities
page 98
How was genetic diversity/variation of alleles investigated in the past?
By looking at frequency of measurable and observable characteristics in a pop
- As different alleles determine different characteristics, a wide variety of characteristics in a pop indicate a high number of different alleles = high genetic diversity
Nowadays, how can we measure genetic diversity directly?
- Comparing DNA base sequences
- Comparing mRNA sequences
- Comparing amino acid sequences
- Observing the frequency of measurable or observable characteristics
