Allometric relations can be studied during the growth of a single organism, between different organisms within a species, or between organisms in different species. amino acid: The unit molecular building block of proteins, which are chains of amino acids in a certain sequence.
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.
Also used to describe the process of genetic change within a population, as influenced by natural selection.
adaptive landscape: A graph of the average fitness of a population in relation to the frequencies of genotypes in it.
The term can also be applied to larger groups of organisms, as in "the adaptive radiation of mammals." adaptive strategies: A mode of coping with competition or environmental conditions on an evolutionary time scale.
Species adapt when succeeding generations emphasize beneficial characteristics.
The pupil of a human eye is a self-adjusting aperture. archetype: The original form or body plan from which a group of organisms develops.
amino acid sequence: A series of amino acids, the building blocks of proteins, usually coded for by DNA.
Exceptions are those coded for by the RNA of certain viruses, such as HIV.
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 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).
These all develop through an embryo that is enclosed within a membrane called an amnion.