His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.
Karyanya memberikan kontribusi terhadap revolusi konseptual yang mengarah kepada sintesis evolusi modern antara genetika Mendel, sistematika, dan evolusi Darwin serta perkembangan konsep spesies biologi.