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).
Also used to describe the process of genetic change within a population, as influenced by natural selection.
amphibians: The class of vertebrates that contains the frogs, toads, newts, and salamanders.
The amphibians evolved in the Devonian period (about 370 million years ago) as the first vertebrates to occupy the land.
antibacterial: Having the ability to kill bacteria.
antibiotics: Substances that destroy or inhibit the growth of microorganisms, particularly disease-causing bacteria.
ammonoid: Extinct relatives of cephalopods (squid, octopi, and chambered nautiluses), these mollusks had coiled shells and are found in the fossil record of the Cretaceous period.
amniotes: The group of reptiles, birds, and mammals.In a diploid cell there are usually two alleles of any one gene (one from each parent).Within a population there may be many different alleles of a gene; each has a unique nucleotide sequence.agnostic: A person who believes that the existence of a god or creator and the nature of the universe is unknowable.algae: An umbrella term for various simple organisms that contain chlorophyll (and can therefore carry out photosynthesis) and live in aquatic habitats and in moist situations on land. Algae range from macroscopic seaweeds such as giant kelp, which frequently exceeds 30 m in length, to microscopic filamentous and single-celled forms such as Spirogyra and Chlorella. For example, if a gene determines the seed color of peas, one allele of that gene may produce green seeds and another allele produce yellow seeds.artifact: An object made by humans that has been preserved and can be studied to learn about a particular time period.