Evolutionary process whereby one species evolves into another without any splitting into multiple species Punctuated Equilibrium Model of the rate of evolution in which there are long periods of little change (stasis) in the species punctuated by short bursts of rapid change (usually due to an environmental change) Extinction. Rapid disappearance of a species.
17th Amendment to the U.S. Constitution: Direct Election of U.S. Senators. Americans did not directly vote for senators for the first 125 years of the Federal Government. The Constitution, as it was adopted in 1788, stated that senators would be elected by state legislatures.
Ratified June 15, 1804. The 12th Amendment changed a portion of Article II, Section 1. A portion of the 12th Amendment was changed by the 20th Amendment. The 20th amendment changed the dates that presidential terms and Congressional sessions started.he Twelfth Amendment cannot be understood outside of the Electoral College, which was set out in the 1787 Constitution as the mechanism by which Americans select their presidents. There were four crucial aspects of that mechanism.