antibiotics: Substances that destroy or inhibit the growth of microorganisms, particularly disease-causing bacteria.
antibiotic resistance: A heritable trait in microorganisms that enables them to survive in the presence of an antibiotic.
adaptive radiation: The diversification, over evolutionary time, of a species or group of species into several different species or subspecies that are typically adapted to different ecological niches (for example, Darwin's finches).
If such a behavior is even partly genetically determined, it will tend to become widespread in the population.
Then, even if circumstances change such that it no longer provides any survival or reproductive advantage, the behavior will still tend to be exhibited -- unless it becomes positively disadvantageous in the new environment.
adaptive landscape: A graph of the average fitness of a population in relation to the frequencies of genotypes in it.
Peaks on the landscape correspond to genotypic frequencies at which the average fitness is high, valleys to genotypic frequencies at which the average fitness is low. adaptive logic: A behavior has adaptive logic if it tends to increase the number of offspring that an individual contributes to the next and following generations.
allopatric speciation: Speciation that occurs when two or more populations of a species are geographically isolated from one another sufficiently that they do not interbreed. There are 20 main amino acids in the proteins of living things, and the properties of a protein are determined by its particular amino acid sequence.