定義: A depressed block of land bordered by parallel faults. A graben is the result of a block of land being downthrown producing a valley with a distinct scarp on each side. Grabens often occur side-by-side with horsts. Horst and graben structures are indicative of tensional forces and crustal stretching.
定義: number of homologous sets of chromosomes in the nucleus or primary chromosome-containing compartment of the cell, each set essentially coding for all the biological traits of the organism.
定義: This organism produces this material or substance, either during its life or after death. A produces B if some process that occurs in A has output B.
定義: A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)