Genetic variation is stored in a populationâs gene poolâthe combined. alleles of all of the individuals in a population. Different combinations of. alleles in a gene pool can be formed when organisms mate and have offspring. Each allele exists at a certain rate, or frequency.
Also found in: Wikipedia. cosÂ·tal surÂ·face. the surface of certain structures that face the ribs; they are the costal surfaces of the lungs (facies costalis pulmonis [TA]) and the scapula (facies costalis scapulae [TA]).
The main functions of this structure are: 1  The Visceral pleura follow the underlying lung surface very closely. 2  It moves down into the fissures and covers the lobes. 3  It gives a smooth, slippery surface to the lungs and allows it to move freely in the parietal pleura.t refers to a swelling of the pleural layers. The visceral pleura, which is the inmost of the two layers, becomes inflamed due to cold weather and certain infections. This can give rise to an acute burning pain which can be experienced while breathing deeply.