Chapter 6 Flashcards
A process of evolutionary change in which traits that confer survival or reproductive advantages tend to increase in frequency in a population over time.
adaptive evolution
An event in which a group of organisms gives rise to many new species that expand into new habitats or new ecological roles in a relatively short time.
adaptive radiation
One of two or more forms of a gene that result in the production of different versions of the protein that the gene encodes.
allele
A pattern of gradual change in a characteristic of an organism over a geographic region.
cline
Selection that favors individuals with one extreme of a heritable phenotypic trait.
directional selection
Selection that favors individuals with a phenotype at either extreme over those with an intermediate phenotype.
disruptive selection
(1) Change in allele frequencies in a population over time. (2) Descent with modification; the process by which organisms gradually accumulate differences from their ancestors.
evolution
A branching diagram that represents the evolutionary history of a group of organisms.
evolutionary tree
(1) The uptake of the gaseous form of a compound, including CO2 in photosynthesis and N2 in nitrogen fixation, by organisms for use in metabolic functions. (2) With respect to the genetic composition of a population, an allele frequency of 100%.
fixation
The transfer of alleles from one population to another via the movement of individuals or gametes.
gene flow
A process in which chance events determine which alleles are passed from one generation to the next, thereby causing allele frequencies to fluctuate randomly over time; the effects are most pronounced in small populations.
genetic drift
The genetic makeup of an individual.
genotype
An event in which a large proportion of Earth’s species are driven to extinction worldwide in a relatively short time.
mass extinction
Change in the DNA of a gene.
mutation
The process by which individuals with certain heritable characteristics tend to survive and reproduce more successfully than other individuals because of those characteristics.
natural selection