Ch.25: Taxonomy and Phylogeny – Key Concepts

Flashcards covering key concepts from Chapter 25 on taxonomy and phylogeny, including definitions of clades, monophyly/paraphyly/polyphyly, homologous vs homoplasy, phylogenetic methods, and taxonomic hierarchy.

What is taxonomy?

The science of naming and classifying extant and extinct organisms within a hierarchical system, placed into groups called taxa.

What is phylogeny?

The evolutionary history of a species or group of species.

What is a clade?

A group that includes all species derived from a common ancestor.

What is a monophyletic group?

A taxon consisting of a common ancestor and all of its descendants; a true clade.

What is a paraphyletic group?

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

What is a polyphyletic group?

A group containing members with different common ancestors.

What is apomorphy?

A novel trait that evolved in a lineage.

What is plesiomorphy?

An ancestral trait shared by members of a lineage.

What is synapomorphy?

A shared derived trait that originated in the most recent common ancestor of two or more taxa.

What is symplesiomorphy?

A shared ancestral character among taxa (older trait).

What is autapomorphy?

A distinctive derived trait unique to a particular taxon.

What is homology?

Similarity due to descent from a common ancestor; homologous features are characters.

What is homoplasy?

Similar traits that arose independently (convergent evolution) with no recent common ancestry.

What is the principle of parsimony in phylogenetics?

The idea that the best hypothesis minimizes the number of evolutionary changes.

What is maximum likelihood in phylogenetics?

A method that evaluates whether a given evolutionary model and tree would produce the observed molecular data.

What is cladistics?

Classification based on evolutionary relationships using shared derived characters.

What is a cladogram?

A branching diagram showing relationships constructed by cladistic methods.

What is a phylogenetic tree?

A hypothesis describing evolutionary relationships among species, revisable with new data.

What is an ingroup?

The group of organisms whose evolutionary relationships are being studied.

What is an outgroup?

A species or group assumed to have diverged before the ingroup, used to root the tree.

What are supergroups in eukaryotes?

Seven broad groups placed between domain and kingdom to classify major eukaryotic lineages.

How many kingdoms are in the five-kingdom system and what are they?

Five: Monera, Protista, Fungi, Plantae, and Animalia.

What is a domain?

The highest taxonomic level above kingdom; includes Bacteria, Archaea, and Eukarya.

What is binomial nomenclature?

The two-part naming system for species introduced by Linnaeus.

Who is Linnaeus?

The founder of taxonomy who introduced binomial nomenclature.

What is a taxon?

Any group at any level in the taxonomic hierarchy (domain, kingdom, phylum, etc.).

Should all taxa be monophyletic?

Yes; ideally taxa should be monophyletic, containing a common ancestor and all its descendants.

How are phyla organized in classification?

Phyla are divided into classes, then orders, families, genera, and species.

What is a character state?

The different forms a character can take (e.g., wing, arm, or flipper); states may be shared or not shared among taxa.

What is horizontal gene transfer?

The acquisition of genetic material from another organism without reproduction.