taxonomy and cladistics

Taxonomy

science of describing, naming, and classifying species

Carl Linnaeus

also known as “Carl Von Linne” or Carolus Linnaeus

father of taxonomy

swedish botanist and physician

introduced the “Linnnaen System” and system of “Binomial Nomenclature”

Kingdom

highest taxon in Linneaen taxonomy

represents major divisions of organisms

Phylum (phyla)

this taxon is a division of a kingdom

class

division of a phylum

order

division of a class

family

division of order

genus

division of family

species

below the genus and lowest taxon in the system

domain

is a taxon that is larger and more inclusive than the kingdom

major change to the Linnaean system when added

International Code of Botanical Nomenclature (ICBN)

plants

International Code of Zoological Nomenclature (ICZN)

animals

International Code of Nomenclature Bacteria (ICNB)

bacteria

International Committee on Taxonomy Viruses

viruses

Generic name (Genus) and Specific Epithet (species)

Scientific name has 2 parts

Phylogenetic Systematics

reconstructs the evolutionary history and studies the patterns of relationships among organisms

Phylogeny and Cladistics

introduce classifications where organisms are grouped based on shared characteristics from the group’s last common ancestor

Phylogenetic tree

a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor

Cladogram

shows how species may be related by descent from a common ancestor

Phylogenetic Classification

a classification of organisms based on such relationships

involves placing organisms in a clade with their common ancestor

Shared Character

a characteristic or trait that 2 or more species have in common

Derived Character

a trait that evolved in a common ancestor of a group of organisms and is passed down to its descendants

Synapomorphy

the scientific term for a shared derived character

Shared Derived Characteristics (Synapomorphies)

most important evidence in cladistics is the presence of shared, derived traits that are not present in more distant groups or ancestors

Morphological Evidence

cladograms were constructed based on the comparison of physical features (morphology) of organisms, looking for similarities and differences in their structures and functions

Molecular Evidence

modern cladistics increasingly relies on molecular data, such as DNA and RNA sequences, to determine evolutionary relationships

Cladistics

is a method of classifying organisms into groups of species called “clades” (from greek “klados” = branch)

each clade consists of an ancestral organism and all of its evolutionary descendants

Root

the initial ancestor common to all organisms within the cladogram

Nodes

each node corresponds to a hypothetical common ancestor that speciated to give rise to 2 or more daughter taxa

Outgroup

most distantly related species in the cladogram

Clades

a common ancestor and all of its descendants