Geophysically Determined Island Habitat History and Colonization of the Galápagos Islands by Central American Iguanas

The Galápagos Islands’ unique endemic flora and fauna originated mainly from colonization from South and Central America, including the famous Galápagos iguanas. Genetic analysis suggests that these iguanas arrived from Central America ~5-12 Ma million years ago (Late Miocene) or even earlier, yet the oldest of the present-day islands were formed at ~3.5 Ma. Recent geophysical analysis shows that now-submerged islands along the Cocos Ridge (Galápagos hotspot track) provided terrestrial habitat for colonization and differentiation during the time frame ~6-18 Ma. Remarkably, this was also a time window during which ocean currents and winds were much more favorable for transport from mainland Central America to these ancient islands, prior to the closing of the Isthmus of Panama at ~3-5 Ma due to regional plate tectonic forces. Thus, we can explain both the colonization timing and provenance of Galápagos iguanas in a framework that shows much promise for understanding the origins of other unique Galápagos species.