Unit 3, topic 1.2: Classification processes Flashcards
Taxonomy
The classification of Earth’s biodiversity into formal groups
Morphology
Classification based on visible characteristics
Five kingdom system
places all prokaryotes in one kingdom of the 5:
Monera, Protista, Fungi, Plantae, Animalia
3 domain system
Domain Bacteria (Bacteria and Cyanobacteria)
Domain Archaea (Archean’s)
Domain Eukarya (Amoebae, plants, animals, fungi, slime moulds)
Six kingdom system
Update of the 1969 five kingdom classification system:
Eubacteria, Archaeabacteria, Protista, Fungi, Plantae, Animalia
Traditional classification (Linnaean system)
Organisms are grouped into taxonomic ranks on the basis of morphology
Taxonomic ranks
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Binomial nomenclature
When species are named by genus and species
Weaknesses of traditional classification
ranks are not equivalent for different types of organisms and unrelated species can be grouped together because they look alike, resulting in misclassification
Phylogenetic classification
Ties names to clades/evolutionary history: Cladistics
Characteristics used to assign organisms to a clade can be morphological or molecular (DNA or proteins)
Clade
A taxonomic group that consists of an ancestor and all its’ descendants
Classification by mode of reproduction
BROAD:
Asexual reproduction, cycles of sexual and asexual reproduction, exclusively sexual reproduction
Classification by life history strategy
Organisms can be grouped according to how they allocate their resources to growth and reproduction → R-selected and K-selected
R-selected organism
small, fast-growing organisms that live in unstable environments and produce a large number of offspring
K-selected organism
large, slow-growing organisms that live in stable environments and produce only a few offspring that they can give a lot of care to
Species definition
Biological species: two organisms with the ability to successfully interbreed
Phylogenetic species: Two organisms with shared evolutionary history
Weaknesses of species definitions
Biological species: difficult application to Asexual organisms and extinct organisms
Phylogenetic species: Requires enough geometric diversity to evaluate and can result in the proliferation of a species
Phylogenetics
The study of the evolutionary history of organisms or a group of organisms and their relationships
Phylogenetic trees
a graphical representation of evolutionary relationships among biological taxa
Molecular Phylogenetics
Analyses heritable molecular differences to find out about an organisms evolutionary relationships
Cladogram
A phylogenetic tree constructed using a cladistical approach
DNA barcoding
Takes short highly conserved DNA sequences to produce species-specific information
works on the assumption that each species DNA is different but the more closely related the organisms are, the more similar their DNA will be.
Classification by species interactions
Species can be classified with the nature and outcome of interactions between different species, influencing structure and interdependence
The rule of Parsimony
Assumes that the phylogenetic tree with the simplest explanation (the least number of evolutionary events) is the most likely to show the correct evolutionary relationships
