The Seventeenth Amendment in the National Archives. The Seventeenth Amendment (Amendment XVII) to the United States Constitution established the popular election of United States Senators by the people of the states.riginally, under Article I, Â§ 3, Clauses 1 and 2 of the Constitution, each state legislature elected its state's senators for a six-year term. Each state, regardless of size, is entitled to two senators as part of the Connecticut Compromise between the small and large states.
Development is the process through which an embryo becomes an adult organism and eventually dies. Through development, an organism's genotype is expressed as a phenotype, exposing genes to the action of natural selection.
Natural Selection Acts On. The genotype is the sum total of all the genes in an organism. But not all of those genes are *expressed*. The phenotype is that subset of the genes that are expressed. Since unexpressed genes provide neither advantage nor disadvantage ... natural selection cannot act on unexpressed genes ... only on expressed genes (the phenotype).