Ch 23: Systematics Flashcards
Systematics
The reconstruction and study of evolutionary relationships.
Phylogeny
The evolutionary history of an organism, including which species are closely related and in what order related species evolved; often represented in the form of an evolutionary tree.
Ancestral
A common ancestor of an entire group.
Derived
A characteristic used in taxonomic analysis representing a departure from the primitive form.
Cladistics
A taxonomic technique used for creating hierarchies of organisms that represent true phylogenetic relationships and descent.
Shared derived character
In cladistics, character states that are shared by species and that are different from the ancestral character state.
Character States
In cladistics, one of two or more distinguishable forms of a character, such as the presence or absence of teeth in amniote vertebrates.
Taxonomy
The science of classifying living things. By agreement among taxonomists, no two organisms can have the same name, and all names are expressed in Latin.
Polarize
In cladistics, to determine whether character states are ancestral or derived.
Outgroup
A species or group of species that is closely related to, but not a member of, the group under study is designated as the outgroup.
Cladogram
A diagram that uses a hypothesis to depict the evolutionary relationships between species.
Clade
A taxonomic group composed of an ancestor and all its descendants.
Synapomorphy
In systematics, a derived character that is shared by all clade members.
Plesiomorphy
In cladistics, another term for an ancestral character state.
Symplesiomorphy
In cladistics, another term for a shared ancestral character state.
Homoplasy
In cladistics, a shared character state that has not been inherited from a common ancestor exhibiting that state may result from convergent evolution or evolutionary reversal. The wings of birds and of bats, which are convergent structures, are examples.
Principle of parsimony
Principle stating that scientist should favor the hypothesis that requires the fewest assumptions.
Molecular clock
In evolutionary theory, the method in which the rate of evolution of a molecule is constant through time.
Classification
How scientist place species and higher groups — genus, family, class, and so forth — into the taxonomic hierarchy.
Taxonomy
The science of classifying living things. By agreement among taxonomists, no two organisms can have the same name, and all names are expressed in Latin.
Order
A category of classification above the level of family and below that of class.
Class
A taxonomic category between phyla and orders. A class contains one or more orders, and belongs to a particular phylum.
Phylum
A major category, between kingdom and class, of taxonomic classifications.
Monophyletic
In phylogenetic classification, a group that includes the most recent common ancestor of the group and all its descendants. A clade is a monophyletic group.
Paraphyletic
In phylogenetic classification, a group that includes the most recent common ancestor of the group, but not all its descendants.
Polyphyletic
In phylogenetic classification, a group that does not include the most recent common ancestor of all members of the group.
Phylogenetic species concept(PSC)
The concept that defines species on the basis of their phylogenetic relationships.
