derived -- adj. Refers to a character or feature found within a single lineage of a larger group; it is not shared with all organisms in the larger group. Derived characters are used to infer evolutionary relationships, as derived characters evolved after primitive characters. In comparing humans and apes, it can be said that an upright stance in humans is a derived character.
diagenesis -- n. Any sort of chemical, physical, or biogenic change that occurs in fossils and sediments after their deposition. Physical erosion of a shell in a river, dissolution of carbonate in acidic conditions, and microbial invasion of a bone are all forms of diagenesis. adj. diagenetic
diatomite -- Diatomite, or diatomaceous earth, is a siliceous sedimaentary rock formed from the accumulations of diatoms or other nanoplankton.
dikaryotic -- Having two different and distinct nuclei per cell; found in the fungi. A dikaryotic individual is called a dikaryon.
dinosteranes/dinosteroids -- chemicals found in dinoflagellates, which have been useful in documenting their existence early in the fossil record.
diploid -- Having two different sets of chromosomes in the same nucleus of each cell. Most metazoans and plants are diploid. Compare with haploid.
diploid life cycle -- Occurs when the only multicellular stage in an organism's life cycle is diploid.
disease -- Organisms suffer from disease when their normal function is impaired by some genetic disorder, or more often from the activity of a parasite or other organism living within them. Many diseases are caused by viruses, bacteria, or fungi.
dispersal -- The scattering of organisms of a species, often following a major reproductive event. Spores and larvae are commonly dispersed into the environment. Pollen or gametes may also be dispersed, but in this case the intent is to target another individual so that reproduction may occur. Organisms may disperse as spores, seeds, eggs, larvae, or adults.
DNA -- "deoxyribonucleic acid". The nucleic acid which carries the genetic code of an organism. It is the primary component of chromosomes. MORE?
double membrane -- In mitochondria and plastids, there is a two-layered membrane which surrounds the organelle. This is believed to be the result of endosymbiosis, with the outer membrane coming from the eukaryotic cell, and the inner membrane belonging to the original prokaryote which was "swallowed".