Systematics and Phylogeny

These flashcards are designed to help students review key concepts in systematics and phylogeny, including definitions of important terms, mechanisms of classification, and the significance of evolutionary relationships.

What is systematics?

Systematics is the theory and practice of classifying organisms based on evolutionary history (phylogeny).

What is taxonomy?

Taxonomy is the scientific discipline concerned with naming and classifying organisms.

Why are phylogenetic trees important?

Phylogenetic trees help organize biological diversity, visualize evolution, structure classifications, and guide research.

What are sister taxa?

Sister taxa are groups that share an immediate common ancestor.

What is a basal taxon?

A basal taxon diverges early in the history of a group and represents the common ancestor of the group.

What is the difference between homology and analogy?

Homology is similarity due to shared ancestry, while analogy is similarity due to convergent evolution.

What is a cladogram?

A cladogram depicts only the order in which different clades arose, and branch lengths convey no information.

What is a shared derived character?

A shared derived character is an evolutionary novelty unique to a particular clade.

What is cladistics?

Cladistics groups organisms based on common descent, creating a nested structure of clades.

What defines a monophyletic group?

A monophyletic group consists of the ancestral species and all its descendants.

What is a paraphyletic group?

A paraphyletic group consists of an ancestral species and some, but not all, of its descendants.

What is a polyphyletic group?

A polyphyletic group includes distantly related species but does not include their most recent common ancestor.

What are homologous characters?

Homologous characters are anatomical, physiological, or molecular features used to compare taxa.

How do systematists infer phylogenies?

Systematists infer phylogenies using morphological, genetic, and biochemical data.

What is maximum parsimony in phylogenetics?

Maximum parsimony assumes that the tree requiring the fewest evolutionary events is the most likely.

What role do shared characters play in building phylogenetic trees?

Shared characters are used to infer phylogeny and indicate common ancestry.

What is the principle of maximum likelihood?

Maximum likelihood states that a tree can be found that reflects the most likely sequence of evolutionary events.