VQ1 Terms

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

→ Taxonomy

A named taxonomic unit at any given level of classification.

→ Taxon

Unicellular organism that lacks a nucleus or any other membrane-bound organelle.

→ Prokaryote

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

→ Sister taxa

Technique using molecular evidence to identify phylogenetic relationships.

→ Molecular systematics

Structures in different species that are similar because of common ancestry.

→ Homologous structures

A taxonomic level consisting of Bacteria, Archaea, and Eukarya.

→ Domain

Group of populations that interbreed and produce fertile offspring.

→ Species

In microscopy: A measure of the clarity of an image; it is the minimum distance two points can be separated and still be distinguished as two points.

→ Resolution

In microscopy: The area that is visible when looking through a microscope.

→ Field of view

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

→ Phylogenetic tree

The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor.

→ Branch point

In microscopy: The ratio of an object's image size to its actual size.

→ Magnification

In microscopy: The difference in light intensity between different parts of a sample and the background.

→ Contrast

Distantly related taxon that possesses the ancestral state for all characters.

→ Outgroup

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

→ Basal taxon

Homologous genes found in different taxa as a result of a speciation event.

→ Orthologous genes

The evolutionary history of a species or group of related species.

→ Phylogeny

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusion of different organisms.

→ Horizontal gene transfer

A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.

→ Maximum parsimony

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

→ Shared ancestral character

An evolutionary novelty that is unique to a particular clade.

→ Shared derived character

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

→ Cladistics

Organism composed of cells that have a membrane-bound nucleus and several other membrane-bound compartments.

→ Eukaryote

Two-part, Latinized format for naming a species, consisting of the genus and specific epithet.

→ Binomial nomenclature

A phylogenetic tree containing a branch point representing the most recent common ancestor of all taxa in the tree.

→ Basal tree

A group of taxa that consists of a common ancestor and all of its descendants.

→ Monophyletic group

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

→ Paraphyletic group

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

→ Polyphyletic group

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

→ Phylogenetic systematics