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
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