Chapter 8, Processes of Macroevolution Key Terms

metazoa Multicellular animals; a major division of the animal kingdom. chordata The phylum of the animal kingdom that includes vertebrates.

vertebrates Animals with bony backbones; includes fishes, amphibians, reptiles, birds and mammals. homologies Structures that are shared through descent from a common ancestor.

analogies Structures in organisms that are used for the same function, but have developed independently and are not the result of common descent. homoplasy The process by which similarities can develop in different groups of organisms.

evolutionary systematics A traditional approach to classification in which presumed ancestors and descendents are traced in time by analysis of homologous characters. Cladistic taxonomy An approach to taxonomy that groups species according to shared derived characteristics.

ancestral (primitive) Referring to characteristics that are inherited by a group of organisms from a remote ancestor. derived (modified) Referring to characteristics that are modified from the ancestral condition and thus are diagnostic of particular evolutionary lineages.

therapods Small to medium-sized ground-living dinosaurs, dated to approximately 150 m.y.a. and thought to be related to birds. phylogenetic tree A chart showing evolutionary relationships as determined by phylogenetic systematics.

cladogram A chart showing evolutionary relationships as determined by cladistic analysis. It is based solely on interpretation of shared derived characteristics. biological species concept A depiction of species as groups of individuals capable of fertile inbreeding but reproductively isolated from other such groups.

speciation The process where a new species evolves from a prior species. recognition species concept A depiction of species where the key aspect is the ability of individuals to identify members of their own species for purposes of mating.

ecological species concept The concept that a species is a group of organisms exploiting a single niche. allopatric A model of speciation that emphasizes complete reproductive isolation of divergent populations from their ancestral population.

intraspecific Within species, refers to variation seen within the same species. interspecific Between species; refers to variation beyond that seen within the same species to include additional aspects between two different species.

Paleospecies Species defined from fossil evidence, often covering a long time span. genus A group of closely related species.

geological time scale The organization of earth history into eras, periods, and epochs. continental drift The movement of continents on sliding plates of the earth’s surface.

ecological niches The positions of species within their physical and biological environments, together making up the ecosystem. epochs Categories of the geological time scale; subdivisions of periods.

viviparous Giving birth to live young. Heterodont Having different kinds of teeth; characteristic of mammals whose teeth consist of incisors, canines, premolars, and molars.

endothermic Able to maintain internal body temperature. large-bodied hominoids Hominoids including the great apes and hominids as well as all ancestral forms back to the time of divergence from small bodied hominoids.

hominids Colloquial term for members of the family Hominidae, which includes all bipedal hominoids back to the divergence of the African great apes. adaptive radiation The relatively rapid expansion and diversification of life forms into new ecological niches.

punctuated equilibrium The concept that evolutionary change proceeds through long periods of stasis punctuated by rapid periods of change.