Biology Ch. 15

radiometric dating
a method for determining the age of fossils and rocks from the ratio of a radioactive isotope to the nonradioactive isotope(s) of the same element in the sample
continental drift
a change in the position of continents resulting from the incessant slow movement (floating) of the plates of Earth’s crust on the underlying molten mantle; it has caused continents to fuse and break apart periodically throughout geologic history
Pangaea
the supercontinent consisting of all the major landmasses of Earth fused together; continental drift created this near the end of the Paleozoic era
plate tectonics
geologic processes, such as continental drift, volcanoes, and earthquakes, resulting from plate movements
phylogeny
the evolutionary history of a group of organisms
convergent evolution
adaptive change resulting in nonhomologous (analogous) similarities among organisms; species from different evolutionary lineages come to resemble each other (evolve analogous structures) as a result of living in very similar environments
analogy
the similarity of structure between two species that are not closely related; attributable to convergent evolution
systematics
an analytical approach to the study of the diversity of life and the evolutionary relationships between organisms
binomial
a two-part, latinized name of a species; for example, Homo sapiens (normally italicized)
genus
in classification, the taxonomic category above species; the first part of a species’ binomial; for example, Homo
species
a group whose members possess similar anatomical characteristics and have the ability to interbreed
family
in classification, the taxonomic category above genus
order
in classification, the taxonomic category above family
class
in classification, the taxonomic category above order
phylum
in classification, the taxonomic category above class and below kingdom; members of these all have a similar general body plan
kingdom
in classification, the broad taxonomic category above phylum or division
domain
a taxonomic category above the kingdom level; the three of these of life are Archaea, Bacteria, and Eukarya
taxon
a proper name, such as phylum Chordata, class Mammalia, or Homo sapiens, in the taxonomic hierarchy used to classify organisms
phylogenetic tree
a branching diagram that represents a hypothesis about evolutionary relationships between organisms
cladistics
the study of evolutionary history; specifically, the scientific search for monophyletic taxa (clades), taxonomic groups composed of an ancestor and all its descendants
clades
evolutionary branches that consist of an ancestor 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 derived characters
homologous features that have changed from a primitive (ancestral) condition and that are unique to an evolutionary lineage; features found in members of a lineage but not found in ancestors of the lineage
shared primitive characters
homologous features found in members of a lineage and also in the ancestors of the lineage; ancestral features
cladogram
a diagram depicting patterns of shared characteristics among species
ingroup
in a cladistic study of evolutionary relationships among taxa of organisms, the group of taxa that is actually being analyzed
outgroup
in a cladistic study of evolutionary relationships among taxa of organisms, a taxon or group of taxa with a known relationship to, but not a member of, the taxa being studied
parsimony
in scientific studies, the search for the least complex explanation for an observed phenomenon
molecular systematics
comparing nucleic acids or other molecules to infer relatedness
molecular clock
evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates
five-kingdom system
the system of taxonomic classification based on five basic groups: Monera, Protista, Plantae, Fungi, and Animalia
three-domain system
the system of taxonomic classification based on three basic groups: Bacteria, Archaea, and Eukarya