Dictionary of Evolutionary Nomenclature - Letter F

fact: A natural phenomenon repeatedly confirmed by observation.

family: The category of taxonomic classification between order and genus (see taxon). Organisms within a family share a close similarity; for example, the catfamily, Felidae, which includes lions and domestic cats.

fauna: Animal life; often used to distinguish from plant life ("flora").

fermentation: A series of reactions occurring under anaerobic conditions(lacking oxygen) in certain microorganisms (particularly yeasts) in which organic compounds such as glucose are converted into simpler substances with the release of energy. Fermentation is involved in bread making, where the carbon dioxide produced by the yeast causes dough to rise.

fetus: The embryo of a mammal that has reached a stage of development in the uterus in which most of the adult features are recognizable. Specifically in humans it refers to the stage of development after the appearance of bone cells, a process occurring 7 to 8 weeks after fertilization.

fitness: The success of an individual (or allele or genotype in a population) in surviving and reproducing, measured by that individual's (or allele's orgenotype's) genetic contribution to the next generation and subsequent generations.

FitzRoy, Robert: Captain of the Beagle, which took Charles Darwin on his famousvoyage to South America and around the world. FitzRoy's chief mission on the Beagle was to chart the coast of South America. He also established the first weather warning system while on his journeys, with the help of the telegraph, and later rose to the rank of Admiral in the British Navy. He was known as a young man for his moody temperament, and in his older age for questionable sanity; FitzRoy's life ended in suicide.

fixation: A gene has achieved fixation when its frequency has reached 100 percent in the population.

fixed: (1) In population genetics, a gene is "fixed" when it has a frequency of 100 percent. (2) In creationism, species are described as "fixed" in the sense that they are believed not to change their form, or appearance, through time.

Flammer, Larry: A retired high school biology teacher and co-founder of the Santa Clara County Biotechnology-Education Partnership, which provides teacher training and lab equipment for local schools. He is a current member and Webwriter for the Evolution and Nature of Science Institute (ENSI).

flora: Plant life; often used to distinguish from animal life ("fauna").

foraminifera: These invertebrates are very common in the global ocean, and their distinctive, chambered shells are common in the fossil record as far back as 550million years. Although very few today exceed 9 mm in diameter, fossils have been found that measure 15 cm across.

fossil: Most commonly, an organism, a physical part of an organism, or an imprint of an organism that has been preserved from ancient times in rock, amber, or by some other means. New techniques have also revealed the existence of cellular and molecular fossils.

founder effect: The loss of genetic variation when a new colony is formed by a very small number of individuals from a larger population.

frequency-dependent selection: Selection in which the fitness of a genotype (or phenotype) depends on its frequency in the population.

fungi: A group of organisms comprising the kingdom Fungi, which includes molds and mushrooms. They can exist either as single cells or make up a multicellular body called a mycelium. Fungi lack chlorophyll and secrete digestive enzymes that decompose other biological tissues.