Delimitation of the three periods in the study of Galápagos ants. Period I: 1877–1933; Period II: 1933 until the end of the 1990’s; Period III: 2000 onwards. The following references correspond to the years listed in the figure: 1877 = Smith (1877); 1893 = Emery (1893); 1919 = Wheeler (1919); 1924 = Wheeler (1924); 1933 = Wheeler (1933); 1972 = Silberglied (1972); 1982 = Clark et al. (1982); 1984 = Lubin (1984); 1992 = (Snelling and Longino 1992); 1998 = Pezzatti et al. (1998); 2007 – 2011 = Pacheco et al. (2007), Herrera and Longino (2008), Herrera and Causton (2010), Lattke (2011); 2013 – 2014 = Herrera et al. (2013, 2014).