AP Biology: Chapter 26 Vocab - Phylogeny and the Tree of Life

Analogy (Analogous structures)

Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait

Basal Taxon

In a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group

Binomial

A common term for the two-part, latinized format for naming a species, consisting of the genus and specific epithet; also called a binomen

Branch points

The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. This is usually shown as a dichotomy in which a branch representing the ancestral lineage splits into two branches, one for each of the two descendant lineages

Clades

A group of species that includes an ancestral species and all of its descendants. Equivalent to a monophyletic group

Cladistics

An approach to systematics in which organisms are placed into groups called clades based primarily on common descent

Class

A grouping of related orders within a phylum, sharing common traits. In Linnaean classification, the taxonomic category above the level of order

Domain

The highest level of classification, grouping organisms based on fundamental cellular characteristics, with the three main domains being Bacteria, Archaea, and Eukarya. A taxonomic category above the kingdom level

Family

A collection of related genera sharing similar characteristics. In Linnaean classification, the taxonomic category above genus

Genus

A group of closely related species sharing a common ancestry. A taxonomic category above the species level, designated by the first word of a species' two-part scientific name

Homology (Homologous structures)

Similarity in characteristics resulting from a shared ancestry

Kingdom

A large group of organisms sharing significant characteristics, like Animalia (animals), Plantae (plants), Fungi (fungi), Protista (protists), and Monera (bacteria). A taxonomic category, the second broadest after domain

Molecular clock

A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes evolve at constant rates

Molecular systematics

The use of molecular genetics to study the evolution of relationships among individuals and species

Monophyletic

Pertaining to a group of taxa that consists of a common ancestor and all of its descendants. A monophyletic taxon is equivalent to a clade

Order

A group of related families within a class. In Linnaean classification, the taxonomic category above the level of family

Outgroup

A species or group of species from an evolutionary lineage that is known to have diverged before the lineage that contains the group of species being studied. This is selected so that its members are closely related to the group of species being studied, but not as closely related as any study-group members are to each other

Paraphyletic

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants

Phylogenetic tree

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms

Phylogeny

The evolutionary history of a species or group of related species

Phylum

A major division within a Kingdom, containing related classes. In Linnaean classification, the taxonomic category above class

Polyphyletic

Pertaining to a group of taxa that includes distantly related organisms but does not include their most recent common ancestor

Polytomy

In a phylogenetic tree, a branch point from which more than two descendant taxa emerge. Indicates that the evolutionary relationships between the descendant taxa are not yet clear

Rooted

Describing a phylogenetic tree that contains a branch point (often, the one farthest to the left) representing the most recent common ancestor of all taxa in the tree

Shared ancestral character

A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade

Shared derived character

An evolutionary novelty that is unique to a particular clade

Sister taxa

Groups of organisms that share an immediate common ancestor and hence are each other's closest relatives

Species

A population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce viable, fertile offspring with members of other such groups

Systematics

A scientific discipline focused on classifying organisms and determining their evolutionary relationships

Taxon

A named taxonomic unit at any given level of classification

Taxonomic

A scientific discipline concerned with naming and classifying the diverse forms of life