phylogenetic classification

what is the aim of a phylogenetic classification system?

to arrange species into groups based on evolutionary origins and relationships

what is a taxon (pl. taxa)?

a group into which organisms are classified

what is a hierarchy in terms of phylogenetic classification?

smaller groups are placed into larger groups w/ no overlap between groups

how are species usually identified

binomial name consisting of genus and species

why is classification important?

• there are 10s of millions of species of organisms

• classification enables organisms to be arranged so that we can establish evolutionary links

• system must be universal so can be used worldwide

what have we historically based classification on?

• physical appearance

• behaviour

what techniques do we use to classify now?

combination between:

• comparison of base sequences in DNA

• comparison of AA sequences in polypeptides

• immunological comparison

name the principle taxa in order of most to least broad:

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

how do we stylise binomial nomenclature?

• genus capitalised

• species lowercase

• all italicised/underlined (when handwritten)

what is a phylogenetic tree? what do the components represent?

• represents evolutionary links between taxa

• groupings on tree represent physical and genetic differences

• branching points represent common ancestors