Individual species will continually evolve as a result of natural selection. Natural selection is the differential survival and generation of people because of contrasts in phenotype. It is a key system of advancement, the change in heritable qualities of a populace after some time. Natural selection is the differential survival and propagation of people because of contrasts in phenotype. It is a key system of development, the change in heritable qualities of a populace after some time.
The simplest virions consist of two basic components: nucleic acid (single- or double-stranded RNA or DNA) and a protein coat, the capsid, which functions as a shell to protect the viral genome from nucleases and which during infection attaches the virion to specific receptors exposed on the prospective host cell.
