Ch 22: Evolution's Patterns Flashcards
Phylogeny
The history of descent with modification and the accumulation of change over time.
Node
In phylogenetic trees, the point where a branch splits, representing the common ancestor from which the descendant species diverged. In plants, the point on a shoot where one or more leaves are attached.
Phylogenetic Tree
A tree-like diagram representing a hypothesis about the evolutionary relationships among populations or species.
Sister Groups
Groups that are more closely related to each other than either of them is to any other group.
Taxon
A named taxonomic group at any rank, such as a species, a genus, or a family.
Monophylectic
Describes groupings in which all members share a single common ancestor not shared with any other species or group of species.
Paraphylectic
Describes groupings that include some, but not all, the descendants of a common ancestor.
Polyphylectic
Describes groupings that do not include the last common ancestor of all members.
Genus
A group of closely related species.
Family
A group of closely related genera.
Class
In the Linnaean system of classification, a group of closely related orders.
Phylum
A group of closely related classes, defined by having a distinct body plan.
Kingdom
A group of closely related phyla.
Domain
One of the three largest limbs of the tree of life: Eukarya, Bacteria, or Archaea.
Characters
In the discipline of systematics, an anatomical, physiological, or molecular feature of an organism that varies among taxa.
Character States
The observed condition of a character, such as presence or absence of lungs or the arrangement of petals.
Homologous
Describes characters that are similar in different species because of descent from a common ancestor.
Analogous
Describes similar characters that evolved independently in different groups as a result of similar selection pressures; the noun form is analogy.
Synapomorphies
A shared derived character; the basis of cladistic phylogenetic reconstruction.
Cladistics
Phylogenetic reconstruction on the basis of shared evolutionary changes in characters, often called synapomorphies.
Parsimony
Choosing the simplest hypothesis to account for a given set of observations. In phylogenetic reconstruction, opting for the tree requiring the fewest evolutionary steps.
Trace Fossils
A track or trail, such as a dinosaur track or the feeding trails of snails and trilobites, left by an animal as it moves about or burrows into sediments.
Molecular Fossils
Sterols, bacterial lipids, and some pigment molecules, which are relatively resistant to decomposition, that can be preserved in sedimentary rocks, documenting organisms that rarely form conventional fossils.
Geologic Timescale
The series of time divisions that mark Earth’s long history.