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.
Since then the 12 th and 17 th amendments to the US Constitution have respectively expanded the power of the voters to select both their President and their Senators, albeit one's vote for President is still an indirect one due to the Electoral College.1 In addition, several states have enacted several other measures that have increased the power of the people: the initiative, the referendum, and the recall.