Phylogeny and the Tree of Life

Vocabulary practice flashcards defining core terms, tree anatomy, phylogenetic methods, and classification schemes based on Chapter 26 lecture notes.

Phylogenetics

The scientific study of the evolutionary history of a species or group of related species.

Eastern Glass Lizard

A legless lizard species whose phylogenetic position reveals that limblessness evolved independently from snakes in several distinct lizard lineages.

Taxonomy

The scientific discipline concerned with classifying and naming organisms.

Classification

A system used for organizing organisms or information into categories.

Binomial Nomenclature

A system introduced by Carolus Linnaeus in the 18th century that assigns each organism a two-part Latinized scientific name based on morphological resemblances.

Taxon

A named taxonomic unit at any given level of the biological hierarchy (such as Felidae, Mammalia, or Carnivora).

Hierarchical Classification

The organization of living organisms into increasingly inclusive categories: domain, kingdom, phylum, class, order, family, genus, and species.

Genus

The first part of a binomial scientific name; it is capitalized and italicized.

Specific Epithet

The second part of a binomial scientific name, which is unique for each species within a genus and written in lowercase italics.

Systematics

The modern scientific discipline that classifies organisms and determines their evolutionary relationships using phenotypic attributes, genes, and biochemistry.

Phylogenetic Tree

A branching diagram that represents a hypothesis about the evolutionary history and patterns of descent among species or taxa.

Branch Point

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

Sister Taxa

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

Rooted Tree

A phylogenetic tree containing a branch that represents the most recent common ancestor of all taxa shown in the tree.

Basal Taxon

A lineage on a phylogenetic tree that diverges early in the history of a group and originates near the common ancestor.

Polytomy

A branch point in a phylogenetic tree from which more than two descendant groups emerge, signifying an unresolved pattern of divergence.

Gene Tree

A phylogenetic tree that depicts patterns of relatedness among DNA sequences rather than entire taxa, often used to identify DNA unique to particular species.

Homology

Phenotypic and genetic similarity between organisms that is attributable to shared ancestry.

Analogy

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

Convergent Evolution

The process by which similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms belonging to different evolutionary lineages.

Homoplasy

An analogous structure or molecular sequence that evolved independently in different lineages rather than being inherited from a common ancestor.

Cladistics

A biological classification approach that groups organisms together primarily by common descent.

Clade

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

Monophyletic Group

A valid clade consisting of an ancestral species and all of its descendants.

Paraphyletic Group

An erroneous evolutionary grouping consisting of an ancestral species and some, but not all, of its descendants.

Polyphyletic Group

An evolutionary grouping that includes distantly related species but omits their most recent common ancestor.

Shared Ancestral Character

A character that originated in an ancestor of the taxon and remains present across ancestral and descendant lineages.

Shared Derived Character

An evolutionary novelty that is unique to a particular clade and not found in its ancestral lineages.

Outgroup

A species or group of species closely related to the ingroup being studied, but known to have diverged before the ingroup's lineage.

Ingroup

The group of related species whose evolutionary relationships are being examined and compared against an outgroup.

Maximum Parsimony

A principle that assumes the phylogenetic tree requiring the fewest evolutionary events (appearances of shared derived characters) is the most likely hypothesis.

Maximum Likelihood

A 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.

Phylogenetic Bracketing

An analytical approach allowing scientists to predict unknown features of an ancestor based on shared features observed in its living descendants.