Term | Definition |
Classification | The grouping of objects or information based on similarities. |
Taxonomy | the branch of biology that groups and names organisms based on their different characteristics. |
Taxon (taxa) | a group of organisms arranged in a hierarchy |
Binomial nomenclature | Identify organism’s by their genus and species. Name is italics or underlined. Genus is capitalized. |
Phylogeny | the evolutionary history for a group of species. |
Cladistics | a common method to make evolutionary trees. |
Cladogram | an evolutionary tree made using cladistics. |
Eukarya | A domain that includes protists, fungi, plants and animals. |
Prokaryote | A cell or organism that is simple and has no membrane wrapped organelles. Bacteria |
Eukaryote | A cell or organism that has a complex structure including membrane bound organelles and a nucleus |
Domain | A taxonomic ranking above the Linnaean 5/6 kingdom level. There are three domains: Archaea, Bacteria and Eukarya. |
derived character | a taxonomic character shared by members of a clade but not shared by common ancestors. |
Clade | a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life" |
monophyletic | a taxon (group of organisms) which forms a clade, meaning that it consists of an ancestral species and all its descendants. |
polyphyletic | a group characterized by one or more phenotypes which appear to be the same but which have not been inherited from common ancestors. Alternatively, polyphyletic is used to describe multiple ancestral sources |
paraphyletic | a group of organisms that consists of the group's last common ancestor and all descendants of that ancestor excluding a few |
Biological Species Concept | the most widely accepted species concept. It defines species in terms of interbreeding. For instance, Ernst Mayr defined a species as follows: "species are groups of interbreeding natural populations that are reproductively isolated from other such groups." |
Phylogenetic Species Concept | a species is a "tip" on a phylogenic tree, that is, the smallest set of organisms that share an ancestor and can be distinguished from other organisms. |
Morphological Species Concept | groups species according to morphological similarities and ignores other differences such as DNA or inability to reproduce between individuals. Can be used with fossils. |