Biology Chapter 15: Tracing Evolutionary History

Biology Chapter 15: Tracing Evolutionary History

stromatolite
Layered rocks that result from the activities of prokaryotes that bind thin films of sediment together.
radiometric dating
A method for determining the absolute ages of fossils and rocks, based on the half-life of radioactive isotopes.
geologic record
A time scale established by geologists that divides Earth’s history into time periods, grouped into three eons— Archaean, Proterozoic, and Phanerozoic— and further subdivided into eras, periods, and epochs.
plate tectonics
The theory that the continents are part of great plates of Earth’s crust that float on the hot, underlying portion of the mantle. Movements in the mantle cause the continents to move slowly over time.
Pangaea
The supercontinent consisting of all the major landmasses of Earth fused together. Continental drift formed Pangaea near the end of the Paleozoic era.
paedomorphosis
The retention in an adult of juvenile features of its evolutionary ancestors.
phylogeny
The evolutionary history of a species or group of related species.
convergent evolution
Adaptive change resulting in nonhomologous (analogous) similarities among organisms. Species from different evolutionary lineages come to resemble each as a result of living in very similar environments.
analogy
The similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.
systematics
A scientific discipline focused on classifying organisms and determining their evolutionary relationships.
taxonomy
The branch of biology that identifies, names, and classifies species.
binomial
A two-part, Latinized name of a species; for example, Homo sapiens.
genus
(plural, genera) In classification, the taxonomic category above species; the first part of a species’ binomial; for example, Homo.
family
In classification, the taxonomic category above genus.
order
In classification, the taxonomic category above family.
class
In classification, the taxonomic category above order.
phyla
In classification, the taxonomic category above class.
kingdom
In classification, the broad taxonomic category above phylum.
domain
A taxonomic category above the kingdom level. The three domains of life are Archaea, Bacteria, and Eukarya.
taxon
A named taxonomic unit at any given level of classification.
phylogenetic tree
A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.
cladistics
An approach to systematics in which common descent is the primary criterion used to classify organisms by placing them into groups called clades.
clade
A group of species that includes an ancestral species and all its descendants.
monophyletic
Pertaining to a taxon derived from a single ancestral species that gave rise to no species in any other taxa.
shared ancestral character
A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.
shared derived character
An evolutionary novelty that is unique to a particular clade.
outgroup
In a cladistic study of evolutionary relationships among taxa of organisms, a taxon or group of taxa known to have diverged before the lineage that contains the group of species being studied.
ingroup
In a cladistic study of evolutionary relationships among taxa of organisms, the group of taxa that is actually being analyzed.
parsimony
In scientific studies, the search for the least complex explanation for an observed phenomenon.
molecular systematics
A scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships.
molecular clock
Evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates.
three-domain system
The branch of biology that identifies, names, and classifies species.
horizontal gene transfer
The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps, fusions of different organisms.