Taxonomy and Phylogeny Vocabulary

Vocabulary flashcards covering core terms, concepts, and diagrams from the lecture on taxonomy, cladistics, and phylogenetic trees.

Taxonomy

The scientific discipline concerned with naming and classifying organisms.

Nomenclature

The system of rules for naming things.

Binomial Nomenclature

The two-part scientific naming system for species instituted by Carolus Linnaeus, consisting of the genus name and the specific epithet.

Genus

The first part of a binomial scientific name, which is capitalized and italicized.

Specific Epithet

The second part of a binomial scientific name, which is unique to each species within a genus.

Hierarchical Classification

A system of grouping species into increasingly broader categories: domain, kingdom, phylum, class, order, family, genus, and species.

Taxon

A named taxonomic unit at any level of the biological hierarchy.

Three Domains of Life

The broadest level of biological classification based on DNA sequence comparisons, consisting of Domain Bacteria, Domain Archaea, and Domain Eukarya.

Phylogenetic Tree

A branching diagram that visually represents a hypothesis about the evolutionary relationships among a group of organisms.

Branch Point

A node on a phylogenetic tree representing the divergence of two evolutionary lineages from a common ancestor.

Sister Taxa

Groups of organisms that share an immediate common ancestor that is not shared by any other group.

Rooted Tree

A phylogenetic tree that includes a branch representing the last common ancestor of all taxa in the tree.

Basal Taxon

A lineage that diverges early in the history of a group and represents the common ancestor originating near the base of the group.

Homology

Phenotypic and genetic similarity between organisms due to shared ancestry.

Analogy

Similarity between organisms due to convergent evolution rather than shared ancestry.

Convergent Evolution

The process by which similar environmental pressures and natural selection produce similar adaptations in organisms from different evolutionary lineages.

Homoplasy

An analogous structure or molecular sequence that evolved independently in separate lineages.

Cladistics

An approach to biological classification in which organisms are grouped primarily by common descent.

Clade

A group of species that includes an ancestral species and all of its descendants.

Monophyletic Group

A group (clade) consisting of an ancestral species and all of its descendants.

Paraphyletic Group

A group consisting of an ancestral species and some, but not all, of its descendants.

Polyphyletic Group

A group that includes distantly related species but does not include their most recent common ancestor.

Shared Ancestral Character

A character that originated in an ancestor of the taxon and is present in its members.

Shared Derived Character

An evolutionary novelty unique to a particular clade that was not present in its ancestor.

Ingroup

The primary group of related species being studied in a phylogenetic analysis.

Outgroup

A species or group of species closely related to the ingroup, but known to have diverged before it, used as a basis of comparison.

Maximum Parsimony

The principle assuming that the phylogenetic tree requiring the fewest evolutionary events (molecular changes) is the most likely.

Maximum Likelihood

The principle stating that, given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events.

Cladogram

A phylogenetic tree that depicts only the order in which different clades arose, where branch lengths carry no meaning regarding time or degree of change.

Phylogram

A phylogenetic tree in which branch lengths are proportional to evolutionary change (such as genetic distance) or chronological time.