Chapter 23: Systematics, Phylogenies, and Comparative Biology

Vocabulary flashcards covering key terms from Chapter 23: Systematics, Phylogenies, and Comparative Biology.

Systematics

The study of evolutionary relationships, understanding the history of ancestor-descendant relationships, and uniting all forms of life on Earth.

Phylogenies

The evolutionary history of a group of organisms, tracing their ancestral lineage and relationships through time, often visualized through phylogenetic trees.

Phylogenetic trees

Branching diagrams that show how species diverged from common ancestors.

Descent with modification

Darwin's vision that all species were descended from a single common ancestor, depicting the history of life as a branching tree.

Convergent evolution

A process where two species independently evolve the same features because they use similar environments and similar adaptations are favored.

Evolutionary reversal

A process in which a species re-evolves the characteristics of an ancestral species.

Cladistics

An approach where systematists construct phylogenetic hypotheses based on ancestral and derived characters.

Ancestral characters (Symplesiomorphies)

Similar characters among species that are inherited from the most recent common ancestor of an entire group; not informative about phylogenetic relationships.

Derived characters (Synapomorphies)

Characteristics that represent a departure from the ancestral form; not inherited from the most recent common ancestor of the group.

Shared derived characters

Character states that are shared by species and that are different from the ancestral character state; informative in determining evolutionary relationships.

Character states

One of two or more distinguishable forms of a character (e.g., presence or absence of a tail in vertebrates).

Taxon

A species or higher-level group, such as a genus or family.

Outgroup

A species or group of species that is closely related to, but not a member of, the group under study, used to assign character state as ancestral or derived.

Clade

Evolutionary units that refer to a common ancestor and all its descendants, indicated by possession of shared derived characters.

Homoplasy

A shared derived character state that has not been inherited from a common ancestor exhibiting that character state, resulting from convergent evolution or evolutionary reversal.

Principle of parsimony

Favors the hypothesis that requires the fewest assumptions; the phylogeny that requires the fewest evolutionary events is considered the best hypothesis of phylogenetic relationships.

Taxonomy

The science of classifying organisms.

Binomial nomenclature

A universal and consistent scientific naming system for each species consisting of two words: Genus species.

Domains

The highest hierarchical classification of all life, including Bacteria, Archaea, and Eukarya.

Hierarchical classification

A system of classification including categories from most inclusive to exclusive: Kingdom, Phylum, Class, Order, Family, Genus, Species.

Monophyletic group

A group that includes the most recent common ancestor of the group and all its descendants; a clade.

Paraphyletic group

A group that includes the most recent common ancestor, but not all of its descendants.

Polyphyletic group

A group that includes descendants but does not include their most recent common ancestor.

Phylogenetic species concept

Defines species on the basis of their phylogenetic relationships as groups of populations that have been evolving independently of other groups and are characterized by one or more shared derived characters (synapomorphies).