Ancient DNA from the extinct flightless Haitian Cave-rail (Nesotrochis steganinos) suggests biogeographic connection of the Caribbean and Old World

The worldwide decline in biodiversity during the Holocene has impeded a comprehensive understanding of pre-human biodiversity and biogeography. This is especially true on islands, because many recently extinct island taxa were morphologically unique, complicating assessment of their evolutionary relationships using morphology alone. The Caribbean remains an avian hotspot but was significantly more diverse prior to human arrival in the Holocene. Among the many recently extinct lineages is the enigmatic genus Nesotrochis, which comprises three known flightless species. Based on morphology, Nesotrochis has been considered an aberrant rail (Rallidae). We recovered a nearly complete mitochondrial genome of Nesotrochis steganinos from Holocene fossils, and discovered that it is not a rallid but instead is sister to Sarothruridae, volant birds now restricted to Africa and New Guinea, and the recently extinct, flightless Aptornithidae of New Zealand. This result suggests a widespread or highly dispersive most recent common ancestor of the group. The Caribbean avifauna, prior to human settlement, had a far more cosmopolitan origin than is evident from extant species alone.