- analogy
- (also, homoplasy) characteristic that is similar between organisms by convergent evolution, not due to the same evolutionary path
- basal taxon
- branch on a phylogenetic tree that has not diverged significantly from the root ancestor
- binomial nomenclature
- system of two-part scientific names for an organism, which includes genus and species names
- branch point
- node on a phylogenetic tree where a single lineage splits into distinct new ones
- cladistics
- system used to organize homologous traits to describe phylogenies
- cladograms
- visual representations of evolutionary relationships between organisms
- class
- division of phylum in the taxonomic classification system
- eukaryote-first hypothesis
- proposal that prokaryotes evolved from eukaryotes
- family
- division of order in the taxonomic classification system
- gene transfer agent (GTA)
- bacteriophage-like particle that transfers random genomic segments from one species of prokaryote to another
- genome fusion
- fusion of two prokaryotic genomes, presumably by endosymbiosis
- genus
- division of family in the taxonomic classification system; the first part of the binomial scientific name
- homology
- similarity in characteristics resulting from a shared ancestry
- horizontal gene transfer (HGT)
- (also, lateral gene transfer) transfer of genes between unrelated species
- kingdom
- division of domain in the taxonomic classification system
- maximum parsimony
- applying the simplest, most obvious way with the least number of steps
- mitochondria-first hypothesis
- proposal that prokaryotes acquired a mitochondrion first, followed by nuclear development
- molecular systematics
- technique using molecular evidence to identify phylogenetic relationships
- monophyletic group
- (also, clade) organisms that share a single ancestor
- nucleus-first hypothesis
- proposal that prokaryotes acquired a nucleus first, and then the mitochondrion
- order
- division of class in the taxonomic classification system
- parsimony
- the simplest, most straightforward way of constructing phylogenetic and evolutionary relationships between organisms
- phylogenetic tree
- diagram used to reflect the evolutionary relationships among organisms or groups of organisms
- phylogeny
- evolutionary history and relationship of an organism or group of organisms
- phylum
- (plural: phyla) division of kingdom in the taxonomic classification system
- polytomy
- branch on a phylogenetic tree with more than two groups or taxa
- ring of life
- phylogenetic model where all three domains of life evolved from a pool of primitive prokaryotes
- rooted
- single ancestral lineage on a phylogenetic tree to which all organisms represented in the diagram relate
- shared ancestral character
- describes a characteristic on a phylogenetic tree that is shared by all organisms on the tree
- shared derived character
- describes a characteristic on a phylogenetic tree that is shared only by a certain clade of organisms
- sister taxa
- two lineages that diverged from the same branch point
- systematics
- field of organizing and classifying organisms based on evolutionary relationships
- taxon
- (plural: taxa) single level in the taxonomic classification system
- taxonomic classification system
- hierarchical system of classifying organisms, including the classification of domain, kingdom, phylum, class, order, family, genus, and species
- taxonomy
- science of classifying organisms
- web of life
- phylogenetic model that attempts to incorporate the effects of horizontal gene transfer on evolution