Exploring the combined role of eustasy and oceanic island thermal subsidence in shaping biodiversity on the Galápagos

A significant shift in the understanding of biodiversity patterns on the Galápagos Islands has been revealed through high-resolution palaeogeographical models, which demonstrate that rapid changes in relative sea levels—driven by eustasy and thermal subsidence—have dramatically altered island connectivity over the past 700,000 years. These fluctuations, characterized by periods of extreme lowstands (–140 to –210 m) every ~90,000 years, caused large islands to coalesce, providing land-locked vertebrates with access to vast new territories. Analysis of biological data for groups such as racer snakes, lava lizards, and land iguanas suggests that these geographic upheavals left detectable imprints on their biogeographical distributions. The study proposes that oscillating sea levels may serve as a mechanism to explain evolutionary patterns not only in the Galápagos but also in other island chains like the Maldives, Canaries, and Cape Verde.

Ali, J. R., & Aitchison, J. C. (2014). Exploring the combined role of eustasy and oceanic island thermal subsidence in shaping biodiversity on the Galápagos. Journal of Biogeography, 41(7), 1227–1241. Portico. https://doi.org/10.1111/jbi.12313