Phylogeny and the Tree of Life

Comprehensive vocabulary flashcards covering the concepts of phylogeny, taxonomy, and cladistics based on the Chapter 26 lecture notes.

Phylogeny

The evolutionary relationships of a group of organisms.

Common Ancestor

Represented by a branch point, this is the progenitor from which all descendant groups in a lineage arose.

Sister Group

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

Hatch mark

A visual representation on a phylogenetic tree that signifies a character shared by the groups to the right of the mark.

Homology

Similarities between organisms that are due to common ancestry.

Analogy

Similarities between organisms due to common adaptation or convergent evolution rather than shared ancestry.

Convergent Evolution

The process by which unrelated lineages independently evolve similar traits, such as the legless body forms in snakes and glass lizards.

Carolus Von Linnaeus

The Swedish naturalist who proposed the universal system of binomial nomenclature and the hierarchical classification system.

Binomial Nomenclature

A universal naming system using two-part Latinized names consisting of a Genus and a species epithet.

Genus

The first part of a binomial scientific name; it is always capitalized and italicized (or underlined when handwritten).

Species Epithet

The second part of a binomial scientific name; it is lowercase and italicized.

Subspecies

Regionally distinct groups (morphologically and genetically) within a single species, recognized with a third epithet in their scientific name.

Linnaean Hierarchy

A system of classification where species are placed in increasingly inclusive groups or ranks; remembered by the mnemonic "Look, Did King Phillip Come Over For Green Salad?"

Taxon

A named group at any level of the hierarchical classification system.

Phylogenetic Tree

A branching diagram representing a hypothesis about the evolutionary history and relationships of a group of organisms.

Evolutionary Lineage

A sequence of ancestral organisms leading to a particular descendant taxon, represented by a branch in a tree.

Basal Taxon

A lineage that diverges early in the history of a group from all other members of that group.

Cladistics

A method for inferring phylogeny where common ancestry is the primary criterion used to classify organisms into groups called clades.

Clade

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

Monophyletic Group

A group, also known as a clade, that consists 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 of species where the most recent common ancestor of its members is not part of the group.

Shared Ancestral Character

A trait found in a clade that originated in an ancestor of the taxon, such as a backbone in mammals.

Shared Derived Character

A trait that is unique to a specific clade and not found in their ancestors, such as body hair in mammals.

Ingroup

The specific species or group of species being studied in a phylogenetic analysis.

Outgroup

A species or group that is closely related to the group being studied but is not part of that group, used for comparison.

Proportional Branch Length (Genetic)

A phylogenetic tree where the length of a branch represents the number of changes that have occurred in a particular DNA sequence in that lineage.

Proportional Branch Length (Time)

A phylogenetic tree where branch lengths reflect the time of existence or the chronological points at which lineages diverged, often based on fossil data.