Unit 1 - Evolution Week 3: Phylogenetics

Vocabulary flashcards covering key terms from the Phylogenetics lecture notes, including systematics, phylogeny, cladistics, and species concepts.

Systematics

The science of organizing biodiversity and inferring evolutionary relationships.

Phylogeny

A hypothesis about the evolutionary relationships among species.

Cladistics

A method of classifying organisms based on shared derived characters to infer relationships.

Clade

A group consisting of a common ancestor and all its descendants.

Monophyletic

Describes a group that includes a common ancestor and all its descendants.

Paraphyletic

A group that includes a common ancestor but not all descendants.

Polyphyletic

A group that does not include the most recent common ancestor of its members.

Synapomorphy

A derived character shared by members of a clade.

Ancestral character

A trait inherited from an earlier ancestor, not unique to the group.

Derived character

A trait that evolved in a lineage and is shared by some descendants.

Outgroup

A taxon used to root a cladogram and polarize character states.

Character state

The observed condition of a character (e.g., tail present vs absent).

Parsimony

The principle that the simplest explanation with the fewest changes is preferred in phylogeny.

Cladogram

A branching diagram showing hypothesized evolutionary relationships based on shared derived characters.

Homologous

Traits derived from the same ancestral source.

Analogous (homoplasy)

Traits that are similar due to convergent evolution, not shared ancestry.

DNA sequence data

Molecular data used to construct phylogenies with many characters.

Biological Species Concept (BSC)

A species is a group of interbreeding populations reproductively isolated from others.

Phylogenetic Species Concept (PSC)

A species defined by a unique set of shared derived characters.

Taxonomy

The science of naming and classifying organisms.

Binomial nomenclature

Two-word scientific name (genus and species); genus capitalized, species lowercase.

Taxonomic ranks

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Mnemonic for ranks

Dear King Philip Came Over For Ginger Snaps.

Systematics vs traditional classification

Systematics uses evolutionary relationships; traditional groups may not reflect phylogeny (e.g., birds from dinosaurs).

Synapomorphy (in cladistics)

A shared derived character informative about a clade.

Characteristic states matrix

A table where 1 indicates a derived state and 0 an ancestral state.

Amniotic membrane

A key derived trait in amniotes enabling terrestrial reproduction.

Beetle diversification and angiosperms

Diversification linked to specialization on flowering plants (angiosperms).

Birds and dinosaurs

Phylogenetics shows birds evolved from theropod dinosaurs, not separate from them.

HIV and SIV phylogeny

HIV descended from SIV with multiple independent cross-species origins; phylogeny can trace infection sources.

Sister taxa

Two taxa that are each other’s closest relatives, sharing a most recent common ancestor.

Most common ancestor in a cladogram

The node at which two lineages split, representing the most recent common ancestor.