According to Beatty (1986), population genetics defines the core of the modern synthesis. In the first few decades of the 20th century, most field naturalists continued to believe that Lamarckian and orthogenic mechanisms of evolution provided the best explanation for the complexity they observed in the living world.
The Netherlands has been a constitutional monarchy since 1815 and a parliamentary democracy since 1848. Previously, it was a republic from 1581 to 1806, and a kingdom between 1806 and 1810 (it was part of France between 1810 and 1813).
The fourth country, Aruba, has been an independent country since 1986. Before the 2010 reforms, the Kingdom of the Netherlands consisted of three countries: the European Netherlands, Aruba, and the Netherlands Antilles. The Antilles encompassed the five islands: Curacao, Sint Maarten, Bonaire, St. Eustatius and Saba.