Mutation that changes the base sequence of DNA, but the alteration has no effect on survival or reproduction--neither helps nor hurts the individual
The relative abundances of alleles of a given gene among all individuals of a population, starting from a theoretical reference point
A theoretical reference point which occurs when a population is not evolving with respect to the gene
Of a population or species, small-scale change in allele frequencies. Occurs by mutation, natural selection, genetic drift, gene flow
Differential survival and reproduction among individuals of a population that vary in the details of their shared traits. Influences the frequency of alleles in a population by operating on phenotypes that have a genetic basis.
Allele frequencies shift in a consistent direction, so forms at one end of a range of phenotypic variation become more common over time.
Forms of a trait at both ends of a range of variation are favored, and intermediate forms are selected against
Mode of natural selection in which some individuals, the genetic winners, out-reproduce others of a population because they are better at securing mates. Most adaptive forms of a trait are those that help individuals defeat same-sex rivals for mates, or are the ones most attractive to the opposite sex.
The maintenance of two or more alleles for a trait in some populations, as a result of natural selection against homozygotes
A form of bottlenecking. Change in allele frequencies that occurs after a few individuals establish a new population
Any mechanism that prevents gene flow between populations. Part of speciation
Formation of daughter species from a population or subpopulation of a parent species; the routes vary in their details and duration
A speciation mode by which a physical barrier separates two population and ends the gene flow between them. Then reproductive isolation mechanisms arise
A speciation mode by which new species form within the home range of an existing species, in the absence of a physical barrier
A speciation mode in which different selection pressures lead to divergences within a single population. May occur when one population extends across a broad region encompassing diverse habitats
The process by which close ecological interatctions between two species cause them to evolve jointly
Adaptation of an existing structure for a completely diffferent purpose; a major evolutionary novelty
A structural or functional modification that bestows upon its bearer the opportunity to exploit a habitat more efficiently or in a novel way